1 Mobile CommunicationsFU Berlin Computer Science Computer Systems & Telematics Prof. Dr.-Ing. Jochen Schiller Prof. Dr.-Ing. Jochen Schiller, 1.1

2 Overview of the lectureIntroduction Use-cases, applications Definition of terms Challenges, history Wireless Transmission frequencies & regulations signals, antennas, signal propagation multiplexing, modulation, spread spectrum, cellular system Media Access motivation, SDMA, FDMA, TDMA (fixed, Aloha, CSMA, DAMA, PRMA, MACA, collision avoidance, polling), CDMA Wireless Telecommunication Systems GSM, HSCSD, GPRS, DECT, TETRA, UMTS, IMT-2000 Satellite Systems GEO, LEO, MEO, routing, handover Broadcast Systems DAB, DVB Wireless LANs Basic Technology IEEE a/b/g, .15, Bluetooth Network Protocols Mobile IP Ad-hoc networking Routing Transport Protocols Reliable transmission Flow control Quality of Service Support for Mobility File systems, WWW, WAP, i-mode, J2ME, ... Outlook Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.2

3 Chapter 1: IntroductionA case for mobility – many aspects History of mobile communication Market Areas of research Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.3

4 Computers for the next decades?Computers are integrated small, cheap, portable, replaceable - no more separate devices Technology is in the background computer are aware of their environment and adapt (“location awareness”) computer recognize the location of the user and react appropriately (e.g., call forwarding, fax forwarding, “context awareness”)) Advances in technology more computing power in smaller devices flat, lightweight displays with low power consumption new user interfaces due to small dimensions more bandwidth per cubic meter multiple wireless interfaces: wireless LANs, wireless WANs, regional wireless telecommunication networks etc. („overlay networks“) Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.4

5 Mobile communication Two aspects of mobility:user mobility: users communicate (wireless) “anytime, anywhere, with anyone” device portability: devices can be connected anytime, anywhere to the network Wireless vs. mobile Examples   stationary computer   notebook in a hotel   wireless LANs in historic buildings   Personal Digital Assistant (PDA) The demand for mobile communication creates the need for integration of wireless networks into existing fixed networks: local area networks: standardization of IEEE , ETSI (HIPERLAN) Internet: Mobile IP extension of the internet protocol IP wide area networks: e.g., internetworking of GSM and ISDN Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.5

6 Applications I Vehicles Emergenciestransmission of news, road condition, weather, music via DAB personal communication using GSM position via GPS local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance Emergencies early transmission of patient data to the hospital, current status, first diagnosis replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc. crisis, war, ... Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.6

7 Typical application: road trafficUMTS, WLAN, DAB, DVB, GSM, cdma2000, TETRA, ... ad hoc Personal Travel Assistant, PDA, Laptop, GSM, UMTS, WLAN, Bluetooth, ... Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.7

8 Mobile and wireless services – Always Best ConnectedUMTS, GSM 115 kbit/s LAN 100 Mbit/s, WLAN 54 Mbit/s GSM/GPRS 53 kbit/s Bluetooth 500 kbit/s DSL/ WLAN 3 Mbit/s UMTS 2 Mbit/s GSM/EDGE 384 kbit/s, DSL/WLAN 3 Mbit/s UMTS, GSM 384 kbit/s GSM 115 kbit/s, WLAN 11 Mbit/s Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.8

9 Applications II Travelling salesmen Replacement of fixed networksdirect access to customer files stored in a central location consistent databases for all agents mobile office Replacement of fixed networks remote sensors, e.g., weather, earth activities flexibility for trade shows LANs in historic buildings Entertainment, education, ... outdoor Internet access intelligent travel guide with up-to-date location dependent information ad-hoc networks for multi user games History Info Prof. Dr.-Ing. Jochen Schiller, MC SS05 1.9

10 Location dependent servicesLocation aware services what services, e.g., printer, fax, phone, server etc. exist in the local environment Follow-on services automatic call-forwarding, transmission of the actual workspace to the current location Information services „push“: e.g., current special offers in the supermarket „pull“: e.g., where is the Black Forrest Cherry Cake? Support services caches, intermediate results, state information etc. „follow“ the mobile device through the fixed network Privacy who should gain knowledge about the location Prof. Dr.-Ing. Jochen Schiller, MC SS

11 Mobile devices performance Pager receive only tiny displayssimple text messages PDA graphical displays character recognition simplified WWW Laptop/Notebook fully functional standard applications Sensors, embedded controllers Palmtop tiny keyboard simple versions of standard applications Mobile phones voice, data simple graphical displays performance Prof. Dr.-Ing. Jochen Schiller, MC SS

12 Effects of device portabilityPower consumption limited computing power, low quality displays, small disks due to limited battery capacity CPU: power consumption ~ CV2f C: internal capacity, reduced by integration V: supply voltage, can be reduced to a certain limit f: clock frequency, can be reduced temporally Loss of data higher probability, has to be included in advance into the design (e.g., defects, theft) Limited user interfaces compromise between size of fingers and portability integration of character/voice recognition, abstract symbols Limited memory limited value of mass memories with moving parts flash-memory or ? as alternative Prof. Dr.-Ing. Jochen Schiller, MC SS

13 Wireless networks in comparison to fixed networksHigher loss-rates due to interference emissions of, e.g., engines, lightning Restrictive regulations of frequencies frequencies have to be coordinated, useful frequencies are almost all occupied Low transmission rates local some Mbit/s, regional currently, e.g., 53kbit/s with GSM/GPRS Higher delays, higher jitter connection setup time with GSM in the second range, several hundred milliseconds for other wireless systems Lower security, simpler active attacking radio interface accessible for everyone, base station can be simulated, thus attracting calls from mobile phones Always shared medium secure access mechanisms important Prof. Dr.-Ing. Jochen Schiller, MC SS

14 Early history of wireless communicationMany people in history used light for communication heliographs, flags („semaphore“), ... 150 BC smoke signals for communication; (Polybius, Greece) 1794, optical telegraph, Claude Chappe Here electromagnetic waves are of special importance: 1831 Faraday demonstrates electromagnetic induction J. Maxwell ( ): theory of electromagnetic Fields, wave equations (1864) H. Hertz ( ): demonstrates with an experiment the wave character of electrical transmission through space (1888, in Karlsruhe, Germany, at the location of today’s University of Karlsruhe) Prof. Dr.-Ing. Jochen Schiller, MC SS

15 History of wireless communication I1896 Guglielmo Marconi first demonstration of wireless telegraphy (digital!) long wave transmission, high transmission power necessary (> 200kw) 1907 Commercial transatlantic connections huge base stations (30 100m high antennas) 1915 Wireless voice transmission New York - San Francisco 1920 Discovery of short waves by Marconi reflection at the ionosphere smaller sender and receiver, possible due to the invention of the vacuum tube (1906, Lee DeForest and Robert von Lieben) 1926 Train-phone on the line Hamburg - Berlin wires parallel to the railroad track Prof. Dr.-Ing. Jochen Schiller, MC SS

16 History of wireless communication II1928 many TV broadcast trials (across Atlantic, color TV, TV news) 1933 Frequency modulation (E. H. Armstrong) 1958 A-Netz in Germany analog, 160MHz, connection setup only from the mobile station, no handover, 80% coverage, customers 1972 B-Netz in Germany analog, 160MHz, connection setup from the fixed network too (but location of the mobile station has to be known) available also in A, NL and LUX, customer in D 1979 NMT at 450MHz (Scandinavian countries) 1982 Start of GSM-specification goal: pan-European digital mobile phone system with roaming 1983 Start of the American AMPS (Advanced Mobile Phone System, analog) 1984 CT-1 standard (Europe) for cordless telephones Prof. Dr.-Ing. Jochen Schiller, MC SS

17 History of wireless communication III1986 C-Netz in Germany analog voice transmission, 450MHz, hand-over possible, digital signaling, automatic location of mobile device Was in use until 2000, services: FAX, modem, X.25, , 98% coverage 1991 Specification of DECT Digital European Cordless Telephone (today: Digital Enhanced Cordless Telecommunications) MHz, ~ m range, 120 duplex channels, 1.2Mbit/s data transmission, voice encryption, authentication, up to several user/km2, used in more than 50 countries 1992 Start of GSM in D as D1 and D2, fully digital, 900MHz, 124 channels automatic location, hand-over, cellular roaming in Europe - now worldwide in more than 200 countries services: data with 9.6kbit/s, FAX, voice, ... Prof. Dr.-Ing. Jochen Schiller, MC SS

18 History of wireless communication IV1994 E-Netz in Germany GSM with 1800MHz, smaller cells As Eplus in D ( % coverage of the population) 1996 HiperLAN (High Performance Radio Local Area Network) ETSI, standardization of type 1: GHz, 23.5Mbit/s recommendations for type 2 and 3 (both 5GHz) and 4 (17GHz) as wireless ATM-networks (up to 155Mbit/s) 1997 Wireless LAN - IEEE802.11 IEEE standard, GHz and infrared, 2Mbit/s already many (proprietary) products available in the beginning 1998 Specification of GSM successors for UMTS (Universal Mobile Telecommunication System) as European proposals for IMT-2000 Iridium 66 satellites (+6 spare), 1.6GHz to the mobile phone Prof. Dr.-Ing. Jochen Schiller, MC SS

19 History of wireless communication V1999 Standardization of additional wireless LANs IEEE standard b, GHz, 11Mbit/s Bluetooth for piconets, 2.4Ghz, <1Mbit/s Decision about IMT-2000 Several “members” of a “family”: UMTS, cdma2000, DECT, … Start of WAP (Wireless Application Protocol) and i-mode First step towards a unified Internet/mobile communicaiton system Access to many services via the mobile phone 2000 GSM with higher data rates HSCSD offers up to 57,6kbit/s First GPRS trials with up to 50 kbit/s (packet oriented!) UMTS auctions/beauty contests Hype followed by disillusionment (50 B$ payed in Germany for 6 licenses!) 2001 Start of 3G systems Cdma2000 in Korea, UMTS tests in Europe, Foma (almost UMTS) in Japan Prof. Dr.-Ing. Jochen Schiller, MC SS

20 Wireless systems: overview of the developmentcordless phones wireless LAN cellular phones satellites 1980: CT0 1981: NMT 450 1982: Inmarsat-A 1983: AMPS 1984: CT1 1986: NMT 900 1987: CT1+ 1988: Inmarsat-C 1989: CT 2 1991: CDMA 1991: D-AMPS 1991: DECT 1992: GSM 1992: Inmarsat-B Inmarsat-M 199x: proprietary 1993: PDC 1997: IEEE 1994: DCS 1800 1998: Iridium 1999: 802.11b, Bluetooth 2000: GPRS 2000: IEEE a analogue 2001: IMT-2000 digital 200?: Fourth Generation (Internet based) 4G – fourth generation: when and how? Prof. Dr.-Ing. Jochen Schiller, MC SS

21 Foundation: ITU-R - Recommendations for IMT-2000IMT-2000 concepts and goals M.816-1 framework for services M.817 IMT-2000 network architectures M.818-1 satellites in IMT-2000 M.819-2 IMT-2000 for developing countries M requirements for the radio interface(s) M.1035 framework for radio interface(s) and radio sub-system functions M.1036 spectrum considerations M.1078 security in IMT-2000 M.1079 speech/voiceband data performance M.1167 framework for satellites M.1168 framework for management M.1223 evaluation of security mechanisms M.1224 vocabulary for IMT-2000 M.1225 evaluation of transmission technologies . . . Prof. Dr.-Ing. Jochen Schiller, MC SS

22 Worldwide wireless subscribers (old prediction 1998)700 600 500 Americas 400 Europe Japan 300 others total 200 100 1996 1997 1998 1999 2000 2001 Prof. Dr.-Ing. Jochen Schiller, MC SS

23 Mobile phones per 100 people 199910 20 30 40 50 60 Germany Greece Spain Belgium France Netherlands Great Britain Switzerland Ireland Austria Portugal Luxemburg Italy Denmark Norway Sweden Finland 2005: 70-90% penetration in Western Europe Prof. Dr.-Ing. Jochen Schiller, MC SS

24 Worldwide cellular subscriber growthNote that the curve starts to flatten in 2000 – 2004: 1.5 billion users Prof. Dr.-Ing. Jochen Schiller, MC SS

25 Cellular subscribers per region (June 2002)2004: 715 million mobile phones delivered Prof. Dr.-Ing. Jochen Schiller, MC SS

26 Mobile statistics snapshot (09/2002 / 12/2004)Total Global Mobile Users 869M / 1.52bn Total Analogue Users 71M / 34m Total US Mobile users 145M / 140m Total Global GSM users 680M / 1.25T Total Global CDMA Users 127M / 202m Total TDMA users 84M / 120m Total European users 283M / 343m Total African users 18.5M / 53m Total 3G users 130M / 130m(?) Total South African users 13.2m / 19m European Prepaid Penetration 63% European Mobile Penetration 70.2% Global Phone Shipments m Global Phone Sales 2Q m #1 Mobile Country China (139M / 300m) #1 GSM Country China (99m) #1 SMS Country Philipines #1 Handset Vendor 2Q02 Nokia (37.2%) #1 Network In Africa Vodacom (6.6m) #1 Network In Asia Unicom (153m) #1 Network In Japan DoCoMo #1 Network In Europe T-Mobile (22m / 28m) #1 In Infrastructure Ericsson SMS Sent Globally 1Q02 60T / 135bn SMS sent in UK 6/02 1.3T / 2.1bn SMS sent Germany 1Q02 5.7T GSM Countries on Air 171 / 210 GSM Association members 574 / 839 Total Cost of 3G Licenses in Europe 110T€ SMS/month/user 36 The figures vary a lot depending on the statistic, creator of the statistic etc.! Prof. Dr.-Ing. Jochen Schiller, MC SS

27 Areas of research in mobile communicationWireless Communication transmission quality (bandwidth, error rate, delay) modulation, coding, interference media access, regulations ... Mobility location dependent services location transparency quality of service support (delay, jitter, security) Portability power consumption limited computing power, sizes of display, ... usability Prof. Dr.-Ing. Jochen Schiller, MC SS

28 Simple reference model used hereApplication Application Transport Transport Network Network Network Network Data Link Data Link Data Link Data Link Physical Physical Physical Physical Medium Radio Prof. Dr.-Ing. Jochen Schiller, MC SS

29 Influence of mobile communication to the layer modelApplication layer Transport layer Network layer Data link layer Physical layer service location new applications, multimedia adaptive applications congestion and flow control quality of service addressing, routing, device location hand-over authentication media access multiplexing media access control encryption modulation interference attenuation frequency Prof. Dr.-Ing. Jochen Schiller, MC SS

30 Overview of the main chaptersSupport for Mobility Chapter 9: Mobile Transport Layer Chapter 8: Mobile Network Layer Chapter 4: Telecommunication Systems Chapter 5: Satellite Systems Chapter 6: Broadcast Systems Chapter 7: Wireless LAN Chapter 3: Medium Access Control Chapter 2: Wireless Transmission Prof. Dr.-Ing. Jochen Schiller, MC SS

31 Overlay Networks - the global goalintegration of heterogeneous fixed and mobile networks with varying transmission characteristics regional vertical handover metropolitan area campus-based horizontal handover in-house Prof. Dr.-Ing. Jochen Schiller, MC SS

32 Mobile Communications Chapter 2: Wireless TransmissionFrequencies Signals Antenna Signal propagation Multiplexing Spread spectrum Modulation Cellular systems Prof. Dr.-Ing. Jochen Schiller, MC SS

33 Frequencies for communicationUniversität Karlsruhe Institut für Telematik Frequencies for communication Mobilkommunikation SS 1998 twisted pair coax cable optical transmission 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100 m 3 THz 1 m 300 THz VLF LF MF HF VHF UHF SHF EHF infrared visible light UV VLF = Very Low Frequency UHF = Ultra High Frequency LF = Low Frequency SHF = Super High Frequency MF = Medium Frequency EHF = Extra High Frequency HF = High Frequency UV = Ultraviolet Light VHF = Very High Frequency Frequency and wave length:  = c/f wave length , speed of light c  3x108m/s, frequency f Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

34 Frequencies for mobile communicationVHF-/UHF-ranges for mobile radio simple, small antenna for cars deterministic propagation characteristics, reliable connections SHF and higher for directed radio links, satellite communication small antenna, beam forming large bandwidth available Wireless LANs use frequencies in UHF to SHF range some systems planned up to EHF limitations due to absorption by water and oxygen molecules (resonance frequencies) weather dependent fading, signal loss caused by heavy rainfall etc. Prof. Dr.-Ing. Jochen Schiller, MC SS

35 Frequencies and regulationsITU-R holds auctions for new frequencies, manages frequency bands worldwide (WRC, World Radio Conferences) Prof. Dr.-Ing. Jochen Schiller, MC SS

36 Signals I physical representation of datafunction of time and location signal parameters: parameters representing the value of data classification continuous time/discrete time continuous values/discrete values analog signal = continuous time and continuous values digital signal = discrete time and discrete values signal parameters of periodic signals: period T, frequency f=1/T, amplitude A, phase shift  sine wave as special periodic signal for a carrier: s(t) = At sin(2  ft t + t) Prof. Dr.-Ing. Jochen Schiller, MC SS

37 Fourier representation of periodic signals1 1 t t ideal periodic signal real composition (based on harmonics) Prof. Dr.-Ing. Jochen Schiller, MC SS

38 Signals II Different representations of signalsamplitude (amplitude domain) frequency spectrum (frequency domain) phase state diagram (amplitude M and phase  in polar coordinates) Composed signals transferred into frequency domain using Fourier transformation Digital signals need infinite frequencies for perfect transmission modulation with a carrier frequency for transmission (analog signal!) A [V] Q = M sin  A [V] t[s]  I= M cos   f [Hz] Prof. Dr.-Ing. Jochen Schiller, MC SS

39 Antennas: isotropic radiatorRadiation and reception of electromagnetic waves, coupling of wires to space for radio transmission Isotropic radiator: equal radiation in all directions (three dimensional) - only a theoretical reference antenna Real antennas always have directive effects (vertically and/or horizontally) Radiation pattern: measurement of radiation around an antenna z y z ideal isotropic radiator y x x Prof. Dr.-Ing. Jochen Schiller, MC SS

40 Antennas: simple dipolesReal antennas are not isotropic radiators but, e.g., dipoles with lengths /4 on car roofs or /2 as Hertzian dipole  shape of antenna proportional to wavelength Example: Radiation pattern of a simple Hertzian dipole Gain: maximum power in the direction of the main lobe compared to the power of an isotropic radiator (with the same average power) /4 /2 y y z simple dipole x z x side view (xy-plane) side view (yz-plane) top view (xz-plane) Prof. Dr.-Ing. Jochen Schiller, MC SS

41 Antennas: directed and sectorizedOften used for microwave connections or base stations for mobile phones (e.g., radio coverage of a valley) y y z directed antenna x z x side view (xy-plane) side view (yz-plane) top view (xz-plane) z z sectorized antenna x x top view, 3 sector top view, 6 sector Prof. Dr.-Ing. Jochen Schiller, MC SS

42 Antennas: diversity Grouping of 2 or more antennas Antenna diversitymulti-element antenna arrays Antenna diversity switched diversity, selection diversity receiver chooses antenna with largest output diversity combining combine output power to produce gain cophasing needed to avoid cancellation /2 /2 /4 /2 /4 /2 + + ground plane Prof. Dr.-Ing. Jochen Schiller, MC SS

43 Signal propagation rangesTransmission range communication possible low error rate Detection range detection of the signal possible no communication possible Interference range signal may not be detected signal adds to the background noise sender transmission distance detection interference Prof. Dr.-Ing. Jochen Schiller, MC SS

44 Signal propagation Propagation in free space always like light (straight line) Receiving power proportional to 1/d² in vacuum – much more in real environments (d = distance between sender and receiver) Receiving power additionally influenced by fading (frequency dependent) shadowing reflection at large obstacles refraction depending on the density of a medium scattering at small obstacles diffraction at edges shadowing reflection refraction scattering diffraction Prof. Dr.-Ing. Jochen Schiller, MC SS

45 Real world example Prof. Dr.-Ing. Jochen Schiller, MC SS

46 Multipath propagationSignal can take many different paths between sender and receiver due to reflection, scattering, diffraction Time dispersion: signal is dispersed over time  interference with “neighbor” symbols, Inter Symbol Interference (ISI) The signal reaches a receiver directly and phase shifted  distorted signal depending on the phases of the different parts multipath pulses LOS pulses signal at sender signal at receiver Prof. Dr.-Ing. Jochen Schiller, MC SS

47 Effects of mobility Channel characteristics change over time and location signal paths change different delay variations of different signal parts different phases of signal parts  quick changes in the power received (short term fading) Additional changes in distance to sender obstacles further away  slow changes in the average power received (long term fading) long term fading power t short term fading Prof. Dr.-Ing. Jochen Schiller, MC SS

48 Multiplexing Multiplexing in 4 dimensionsspace (si) time (t) frequency (f) code (c) Goal: multiple use of a shared medium Important: guard spaces needed! channels ki k1 k2 k3 k4 k5 k6 c t c s1 t s2 f f c t s3 f Prof. Dr.-Ing. Jochen Schiller, MC SS

49 Frequency multiplex Separation of the whole spectrum into smaller frequency bands A channel gets a certain band of the spectrum for the whole time Advantages: no dynamic coordination necessary works also for analog signals Disadvantages: waste of bandwidth if the traffic is distributed unevenly inflexible guard spaces k1 k2 k3 k4 k5 k6 c f t Prof. Dr.-Ing. Jochen Schiller, MC SS

50 Time multiplex A channel gets the whole spectrum for a certain amount of time Advantages: only one carrier in the medium at any time throughput high even for many users Disadvantages: precise synchronization necessary k1 k2 k3 k4 k5 k6 c f t Prof. Dr.-Ing. Jochen Schiller, MC SS

51 Time and frequency multiplexCombination of both methods A channel gets a certain frequency band for a certain amount of time Example: GSM Advantages: better protection against tapping protection against frequency selective interference higher data rates compared to code multiplex but: precise coordination required k1 k2 k3 k4 k5 k6 c f t Prof. Dr.-Ing. Jochen Schiller, MC SS

52 Code multiplex Each channel has a unique codeAll channels use the same spectrum at the same time Advantages: bandwidth efficient no coordination and synchronization necessary good protection against interference and tapping Disadvantages: lower user data rates more complex signal regeneration Implemented using spread spectrum technology k1 k2 k3 k4 k5 k6 c f t Prof. Dr.-Ing. Jochen Schiller, MC SS

53 Modulation Digital modulation Analog modulation Motivationdigital data is translated into an analog signal (baseband) ASK, FSK, PSK - main focus in this chapter differences in spectral efficiency, power efficiency, robustness Analog modulation shifts center frequency of baseband signal up to the radio carrier Motivation smaller antennas (e.g., /4) Frequency Division Multiplexing medium characteristics Basic schemes Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM) Prof. Dr.-Ing. Jochen Schiller, MC SS

54 Modulation and demodulationanalog baseband signal digital data digital modulation analog modulation radio transmitter radio carrier analog baseband signal digital data analog demodulation synchronization decision radio receiver radio carrier Prof. Dr.-Ing. Jochen Schiller, MC SS

55 Digital modulation Modulation of digital signals known as Shift KeyingAmplitude Shift Keying (ASK): very simple low bandwidth requirements very susceptible to interference Frequency Shift Keying (FSK): needs larger bandwidth Phase Shift Keying (PSK): more complex robust against interference 1 1 t 1 1 t 1 1 t Prof. Dr.-Ing. Jochen Schiller, MC SS

56 Advanced Frequency Shift Keyingbandwidth needed for FSK depends on the distance between the carrier frequencies special pre-computation avoids sudden phase shifts  MSK (Minimum Shift Keying) bit separated into even and odd bits, the duration of each bit is doubled depending on the bit values (even, odd) the higher or lower frequency, original or inverted is chosen the frequency of one carrier is twice the frequency of the other Equivalent to offset QPSK even higher bandwidth efficiency using a Gaussian low-pass filter  GMSK (Gaussian MSK), used in GSM Prof. Dr.-Ing. Jochen Schiller, MC SS

57 Example of MSK 1 1 1 1 data bit even 0 1 0 1 even bits odd 0 0 1 11 1 1 data bit even even bits odd signal h n n h value odd bits low frequency h: high frequency n: low frequency +: original signal -: inverted signal high frequency MSK signal t No phase shifts! Prof. Dr.-Ing. Jochen Schiller, MC SS

58 Advanced Phase Shift KeyingBPSK (Binary Phase Shift Keying): bit value 0: sine wave bit value 1: inverted sine wave very simple PSK low spectral efficiency robust, used e.g. in satellite systems QPSK (Quadrature Phase Shift Keying): 2 bits coded as one symbol symbol determines shift of sine wave needs less bandwidth compared to BPSK more complex Often also transmission of relative, not absolute phase shift: DQPSK - Differential QPSK (IS-136, PHS) Q I 1 Q I 11 01 10 00 A t 11 10 00 01 Prof. Dr.-Ing. Jochen Schiller, MC SS

59 Quadrature Amplitude ModulationQuadrature Amplitude Modulation (QAM): combines amplitude and phase modulation it is possible to code n bits using one symbol 2n discrete levels, n=2 identical to QPSK bit error rate increases with n, but less errors compared to comparable PSK schemes Example: 16-QAM (4 bits = 1 symbol) Symbols 0011 and 0001 have the same phase φ, but different amplitude a and 1000 have different phase, but same amplitude.  used in standard 9600 bit/s modems Q 0010 0001 0011 0000 φ a I 1000 Prof. Dr.-Ing. Jochen Schiller, MC SS

60 Hierarchical ModulationDVB-T modulates two separate data streams onto a single DVB-T stream High Priority (HP) embedded within a Low Priority (LP) stream Multi carrier system, about 2000 or 8000 carriers QPSK, 16 QAM, 64QAM Example: 64QAM good reception: resolve the entire 64QAM constellation poor reception, mobile reception: resolve only QPSK portion 6 bit per QAM symbol, 2 most significant determine QPSK HP service coded in QPSK (2 bit), LP uses remaining 4 bit Q 10 I 00 000010 010101 Prof. Dr.-Ing. Jochen Schiller, MC SS

61 Spread spectrum technologyProblem of radio transmission: frequency dependent fading can wipe out narrow band signals for duration of the interference Solution: spread the narrow band signal into a broad band signal using a special code protection against narrow band interference protection against narrowband interference Side effects: coexistence of several signals without dynamic coordination tap-proof Alternatives: Direct Sequence, Frequency Hopping signal power interference spread signal power spread interference detection at receiver f f Prof. Dr.-Ing. Jochen Schiller, MC SS

62 Effects of spreading and interferencedP/df dP/df user signal broadband interference narrowband interference i) ii) f f sender dP/df dP/df dP/df iii) iv) v) f f f receiver Prof. Dr.-Ing. Jochen Schiller, MC SS

63 Spreading and frequency selective fadingchannel quality 2 1 5 6 narrowband channels 3 4 frequency narrow band signal guard space 2 frequency channel quality 1 spread spectrum spread spectrum channels Prof. Dr.-Ing. Jochen Schiller, MC SS

64 DSSS (Direct Sequence Spread Spectrum) IXOR of the signal with pseudo-random number (chipping sequence) many chips per bit (e.g., 128) result in higher bandwidth of the signal Advantages reduces frequency selective fading in cellular networks base stations can use the same frequency range several base stations can detect and recover the signal soft handover Disadvantages precise power control necessary tb user data 1 XOR tc chipping sequence 1 1 1 1 1 1 1 1 = resulting signal 1 1 1 1 1 1 1 tb: bit period tc: chip period Prof. Dr.-Ing. Jochen Schiller, MC SS

65 DSSS (Direct Sequence Spread Spectrum) IIsignal transmit signal user data X modulator chipping sequence radio carrier transmitter correlator lowpass filtered signal sampled sums products received signal data demodulator X integrator decision radio carrier chipping sequence receiver Prof. Dr.-Ing. Jochen Schiller, MC SS

66 FHSS (Frequency Hopping Spread Spectrum) IDiscrete changes of carrier frequency sequence of frequency changes determined via pseudo random number sequence Two versions Fast Hopping: several frequencies per user bit Slow Hopping: several user bits per frequency Advantages frequency selective fading and interference limited to short period simple implementation uses only small portion of spectrum at any time Disadvantages not as robust as DSSS simpler to detect Prof. Dr.-Ing. Jochen Schiller, MC SS

67 FHSS (Frequency Hopping Spread Spectrum) IItb user data 1 1 1 t f td f3 slow hopping (3 bits/hop) f2 f1 t td f f3 fast hopping (3 hops/bit) f2 f1 t tb: bit period td: dwell time Prof. Dr.-Ing. Jochen Schiller, MC SS

68 FHSS (Frequency Hopping Spread Spectrum) IIItransmit signal narrowband signal user data modulator modulator frequency synthesizer hopping sequence transmitter narrowband signal received signal data demodulator demodulator hopping sequence frequency synthesizer receiver Prof. Dr.-Ing. Jochen Schiller, MC SS

69 Cell structure Implements space division multiplex: base station covers a certain transmission area (cell) Mobile stations communicate only via the base station Advantages of cell structures: higher capacity, higher number of users less transmission power needed more robust, decentralized base station deals with interference, transmission area etc. locally Problems: fixed network needed for the base stations handover (changing from one cell to another) necessary interference with other cells Cell sizes from some 100 m in cities to, e.g., 35 km on the country side (GSM) - even less for higher frequencies Prof. Dr.-Ing. Jochen Schiller, MC SS

70 Frequency planning I Frequency reuse only with a certain distance between the base stations Standard model using 7 frequencies: Fixed frequency assignment: certain frequencies are assigned to a certain cell problem: different traffic load in different cells Dynamic frequency assignment: base station chooses frequencies depending on the frequencies already used in neighbor cells more capacity in cells with more traffic assignment can also be based on interference measurements f4 f5 f1 f3 f2 f6 f7 Prof. Dr.-Ing. Jochen Schiller, MC SS

71 Frequency planning II 3 cell cluster 7 cell cluster 3 cell clusterh1 h2 h3 g1 g2 g3 3 cell cluster with 3 sector antennas Prof. Dr.-Ing. Jochen Schiller, MC SS

72 Cell breathing CDM systems: cell size depends on current loadAdditional traffic appears as noise to other users If the noise level is too high users drop out of cells Prof. Dr.-Ing. Jochen Schiller, MC SS

73 Mobile Communications Chapter 3 : Media AccessMotivation SDMA, FDMA, TDMA Aloha Reservation schemes Collision avoidance, MACA Polling CDMA SAMA Comparison Prof. Dr.-Ing. Jochen Schiller, MC SS

74 Motivation Can we apply media access methods from fixed networks?Example CSMA/CD Carrier Sense Multiple Access with Collision Detection send as soon as the medium is free, listen into the medium if a collision occurs (original method in IEEE 802.3) Problems in wireless networks signal strength decreases proportional to the square of the distance the sender would apply CS and CD, but the collisions happen at the receiver it might be the case that a sender cannot “hear” the collision, i.e., CD does not work furthermore, CS might not work if, e.g., a terminal is “hidden” Prof. Dr.-Ing. Jochen Schiller, MC SS

75 Motivation - hidden and exposed terminalsHidden terminals A sends to B, C cannot receive A C wants to send to B, C senses a “free” medium (CS fails) collision at B, A cannot receive the collision (CD fails) A is “hidden” for C Exposed terminals B sends to A, C wants to send to another terminal (not A or B) C has to wait, CS signals a medium in use but A is outside the radio range of C, therefore waiting is not necessary C is “exposed” to B A B C Prof. Dr.-Ing. Jochen Schiller, MC SS

76 Motivation - near and far terminalsTerminals A and B send, C receives signal strength decreases proportional to the square of the distance the signal of terminal B therefore drowns out A’s signal C cannot receive A If C for example was an arbiter for sending rights, terminal B would drown out terminal A already on the physical layer Also severe problem for CDMA-networks - precise power control needed! A B C Prof. Dr.-Ing. Jochen Schiller, MC SS

77 Access methods SDMA/FDMA/TDMAUniversität Karlsruhe Institut für Telematik Access methods SDMA/FDMA/TDMA Mobilkommunikation SS 1998 SDMA (Space Division Multiple Access) segment space into sectors, use directed antennas cell structure FDMA (Frequency Division Multiple Access) assign a certain frequency to a transmission channel between a sender and a receiver permanent (e.g., radio broadcast), slow hopping (e.g., GSM), fast hopping (FHSS, Frequency Hopping Spread Spectrum) TDMA (Time Division Multiple Access) assign the fixed sending frequency to a transmission channel between a sender and a receiver for a certain amount of time The multiplexing schemes presented in chapter 2 are now used to control medium access! Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 15

78 FDD/FDMA - general scheme, example GSM960 MHz 124 200 kHz 935.2 MHz 1 20 MHz 915 MHz 124 890.2 MHz 1 t Prof. Dr.-Ing. Jochen Schiller, MC SS

79 TDD/TDMA - general scheme, example DECT1 2 3 11 12 1 2 3 11 12 t downlink uplink Prof. Dr.-Ing. Jochen Schiller, MC SS

80 Aloha/slotted aloha Mechanism Aloha Slotted Aloharandom, distributed (no central arbiter), time-multiplex Slotted Aloha additionally uses time-slots, sending must always start at slot boundaries Aloha Slotted Aloha collision sender A sender B sender C t collision sender A sender B sender C t Prof. Dr.-Ing. Jochen Schiller, MC SS

81 DAMA - Demand Assigned Multiple AccessChannel efficiency only 18% for Aloha, 36% for Slotted Aloha (assuming Poisson distribution for packet arrival and packet length) Reservation can increase efficiency to 80% a sender reserves a future time-slot sending within this reserved time-slot is possible without collision reservation also causes higher delays typical scheme for satellite links Examples for reservation algorithms: Explicit Reservation according to Roberts (Reservation-ALOHA) Implicit Reservation (PRMA) Reservation-TDMA Prof. Dr.-Ing. Jochen Schiller, MC SS

82 Access method DAMA: Explicit ReservationUniversität Karlsruhe Institut für Telematik Access method DAMA: Explicit Reservation Mobilkommunikation SS 1998 Explicit Reservation (Reservation Aloha): two modes: ALOHA mode for reservation: competition for small reservation slots, collisions possible reserved mode for data transmission within successful reserved slots (no collisions possible) it is important for all stations to keep the reservation list consistent at any point in time and, therefore, all stations have to synchronize from time to time collision t Aloha reserved Aloha reserved Aloha reserved Aloha Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 24

83 Access method DAMA: PRMAUniversität Karlsruhe Institut für Telematik Access method DAMA: PRMA Mobilkommunikation SS 1998 Implicit reservation (PRMA - Packet Reservation MA): a certain number of slots form a frame, frames are repeated stations compete for empty slots according to the slotted aloha principle once a station reserves a slot successfully, this slot is automatically assigned to this station in all following frames as long as the station has data to send competition for this slots starts again as soon as the slot was empty in the last frame reservation 1 2 3 4 5 6 7 8 time-slot ACDABA-F frame1 A C D A B A F ACDABA-F frame2 A C A B A AC-ABAF- collision at reservation attempts frame3 A B A F A---BAFD frame4 A B A F D ACEEBAFD frame5 A C E E B A F D t Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 25

84 Access method DAMA: Reservation-TDMAUniversität Karlsruhe Institut für Telematik Access method DAMA: Reservation-TDMA Mobilkommunikation SS 1998 Reservation Time Division Multiple Access every frame consists of N mini-slots and x data-slots every station has its own mini-slot and can reserve up to k data-slots using this mini-slot (i.e. x = N * k). other stations can send data in unused data-slots according to a round-robin sending scheme (best-effort traffic) e.g. N=6, k=2 N * k data-slots N mini-slots reservations for data-slots other stations can use free data-slots based on a round-robin scheme Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 26

85 MACA - collision avoidanceMACA (Multiple Access with Collision Avoidance) uses short signaling packets for collision avoidance RTS (request to send): a sender request the right to send from a receiver with a short RTS packet before it sends a data packet CTS (clear to send): the receiver grants the right to send as soon as it is ready to receive Signaling packets contain sender address receiver address packet size Variants of this method can be found in IEEE as DFWMAC (Distributed Foundation Wireless MAC) Prof. Dr.-Ing. Jochen Schiller, MC SS

86 MACA examples MACA avoids the problem of hidden terminalsA and C want to send to B A sends RTS first C waits after receiving CTS from B MACA avoids the problem of exposed terminals B wants to send to A, C to another terminal now C does not have to wait for it cannot receive CTS from A A C RTS CTS CTS B A C RTS RTS CTS B Prof. Dr.-Ing. Jochen Schiller, MC SS

87 MACA variant: DFWMAC in IEEE802.11sender receiver idle idle packet ready to send; RTS data; ACK RxBusy time-out; RTS wait for the right to send RTS; CTS time-out  data; NAK ACK time-out  NAK; RTS CTS; data wait for data wait for ACK RTS; RxBusy ACK: positive acknowledgement NAK: negative acknowledgement RxBusy: receiver busy Prof. Dr.-Ing. Jochen Schiller, MC SS

88 Polling mechanisms If one terminal can be heard by all others, this “central” terminal (a.k.a. base station) can poll all other terminals according to a certain scheme now all schemes known from fixed networks can be used (typical mainframe - terminal scenario) Example: Randomly Addressed Polling base station signals readiness to all mobile terminals terminals ready to send can now transmit a random number without collision with the help of CDMA or FDMA (the random number can be seen as dynamic address) the base station now chooses one address for polling from the list of all random numbers (collision if two terminals choose the same address) the base station acknowledges correct packets and continues polling the next terminal this cycle starts again after polling all terminals of the list Prof. Dr.-Ing. Jochen Schiller, MC SS

89 ISMA (Inhibit Sense Multiple Access)Current state of the medium is signaled via a “busy tone” the base station signals on the downlink (base station to terminals) if the medium is free or not terminals must not send if the medium is busy terminals can access the medium as soon as the busy tone stops the base station signals collisions and successful transmissions via the busy tone and acknowledgements, respectively (media access is not coordinated within this approach) mechanism used, e.g., for CDPD (USA, integrated into AMPS) Prof. Dr.-Ing. Jochen Schiller, MC SS

90 Universität Karlsruhe Institut für TelematikAccess method CDMA Mobilkommunikation SS 1998 CDMA (Code Division Multiple Access) all terminals send on the same frequency probably at the same time and can use the whole bandwidth of the transmission channel each sender has a unique random number, the sender XORs the signal with this random number the receiver can “tune” into this signal if it knows the pseudo random number, tuning is done via a correlation function Disadvantages: higher complexity of a receiver (receiver cannot just listen into the medium and start receiving if there is a signal) all signals should have the same strength at a receiver Advantages: all terminals can use the same frequency, no planning needed huge code space (e.g. 232) compared to frequency space interferences (e.g. white noise) is not coded forward error correction and encryption can be easily integrated Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 28

91 CDMA in theory Sender A Sender B Both signals superimpose in spacesends Ad = 1, key Ak = (assign: „0“= -1, „1“= +1) sending signal As = Ad * Ak = (-1, +1, -1, -1, +1, +1) Sender B sends Bd = 0, key Bk = (assign: „0“= -1, „1“= +1) sending signal Bs = Bd * Bk = (-1, -1, +1, -1, +1, -1) Both signals superimpose in space interference neglected (noise etc.) As + Bs = (-2, 0, 0, -2, +2, 0) Receiver wants to receive signal from sender A apply key Ak bitwise (inner product) Ae = (-2, 0, 0, -2, +2, 0)  Ak = = 6 result greater than 0, therefore, original bit was „1“ receiving B Be = (-2, 0, 0, -2, +2, 0)  Bk = = -6, i.e. „0“ Prof. Dr.-Ing. Jochen Schiller, MC SS

92 CDMA on signal level I Ad 1 1 1 1 1 1 1 1 1 1 Ak 1 1 1 1 1 1 1 1 Asdata A Ad 1 1 key A key sequence A 1 1 1 1 1 1 1 1 Ak data  key 1 1 1 1 1 1 1 1 As signal A Real systems use much longer keys resulting in a larger distance between single code words in code space. Prof. Dr.-Ing. Jochen Schiller, MC SS

93 CDMA on signal level II As Bd 1 1 1 1 1 1 1 1 1 Bk 1 1 1 1 1 1 1 1 1 1signal A As data B Bd 1 key B key sequence B 1 1 1 1 1 1 1 1 Bk 1 1 1 1 1 1 1 1 1 1 data  key Bs signal B As + Bs Prof. Dr.-Ing. Jochen Schiller, MC SS

94 CDMA on signal level IIIdata A Ad 1 1 As + Bs Ak (As + Bs) * Ak integrator output comparator output 1 1 Prof. Dr.-Ing. Jochen Schiller, MC SS

95 CDMA on signal level IV Bd 1 1 data B As + Bs Bk (As + Bs) * BkAs + Bs Bk (As + Bs) * Bk integrator output comparator output 1 Prof. Dr.-Ing. Jochen Schiller, MC SS

96 CDMA on signal level V (0) (0) ? As + Bs wrong key K (As + Bs) * Kintegrator output comparator output (0) (0) ? Prof. Dr.-Ing. Jochen Schiller, MC SS

97 SAMA - Spread Aloha Multiple AccessAloha has only a very low efficiency, CDMA needs complex receivers to be able to receive different senders with individual codes at the same time Idea: use spread spectrum with only one single code (chipping sequence) for spreading for all senders accessing according to aloha collision sender A 1 1 narrow band sender B 1 1 send for a shorter period with higher power spread the signal e.g. using the chipping sequence („CDMA without CD“) t Problem: find a chipping sequence with good characteristics Prof. Dr.-Ing. Jochen Schiller, MC SS

98 Comparison SDMA/TDMA/FDMA/CDMAProf. Dr.-Ing. Jochen Schiller, MC SS

99 Mobile Communications Chapter 4: Wireless Telecommunication SystemsUniversität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Communications Chapter 4: Wireless Telecommunication Systems Market GSM Overview Services Sub-systems Components DECT TETRA UMTS/IMT-2000 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

100 Mobile phone subscribers worldwideUniversität Karlsruhe Institut für Telematik Mobile phone subscribers worldwide Mobilkommunikation SS 1998 approx. 1.7 bn 1600 1400 1200 GSM total 1000 TDMA total CDMA total Subscribers [million] 800 PDC total Analogue total W-CDMA 600 Total wireless Prediction (1998) 400 200 1996 1997 1998 1999 2000 2001 2002 2003 2004 year Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

101 Development of mobile telecommunication systemsUniversität Karlsruhe Institut für Telematik Development of mobile telecommunication systems Mobilkommunikation SS 1998 CT0/1 FDMA AMPS CT2 NMT IMT-FT DECT IS-136 TDMA D-AMPS EDGE IMT-SC IS-136HS UWC-136 TDMA GSM GPRS PDC IMT-DS UTRA FDD / W-CDMA HSDPA IMT-TC UTRA TDD / TD-CDMA CDMA IMT-TC TD-SCDMA IS-95 cdmaOne IMT-MC cdma2000 1X EV-DO cdma2000 1X 1X EV-DV (3X) 1G 2G 2.5G 3G Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

102 How does it work? How can the system locate a user?Why don’t all phones ring at the same time? What happens if two users talk simultaneously? Why don’t I get the bill from my neighbor? Why can an Australian use her phone in Berlin? Why can’t I simply overhear the neighbor’s communication? How secure is the mobile phone system? What are the key components of the mobile phone network? Prof. Dr.-Ing. Jochen Schiller, MC SS

103 Universität Karlsruhe Institut für TelematikGSM: Overview Mobilkommunikation SS 1998 GSM formerly: Groupe Spéciale Mobile (founded 1982) now: Global System for Mobile Communication Pan-European standard (ETSI, European Telecommunications Standardisation Institute) simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2)  seamless roaming within Europe possible today many providers all over the world use GSM (more than 200 countries in Asia, Africa, Europe, Australia, America) more than 1.2 billion subscribers in more than 630 networks more than 75% of all digital mobile phones use GSM (74% total) over 200 million SMS per month in Germany, > 550 billion/year worldwide (> 10% of the revenues for many operators) [be aware: these are only rough numbers…] Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

104 Performance characteristics of GSM (wrt. analog sys.)Universität Karlsruhe Institut für Telematik Performance characteristics of GSM (wrt. analog sys.) Mobilkommunikation SS 1998 Communication mobile, wireless communication; support for voice and data services Total mobility international access, chip-card enables use of access points of different providers Worldwide connectivity one number, the network handles localization High capacity better frequency efficiency, smaller cells, more customers per cell High transmission quality high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains) Security functions access control, authentication via chip-card and PIN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

105 Universität Karlsruhe Institut für TelematikDisadvantages of GSM Mobilkommunikation SS 1998 There is no perfect system!! no end-to-end encryption of user data no full ISDN bandwidth of 64 kbit/s to the user, no transparent B-channel reduced concentration while driving electromagnetic radiation abuse of private data possible roaming profiles accessible high complexity of the system several incompatibilities within the GSM standards Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

106 Universität Karlsruhe Institut für TelematikGSM: Mobile Services Mobilkommunikation SS 1998 GSM offers several types of connections voice connections, data connections, short message service multi-service options (combination of basic services) Three service domains Bearer Services Telematic Services Supplementary Services bearer services MS GSM-PLMN transit network (PSTN, ISDN) source/ destination network TE MT TE R, S Um (U, S, R) tele services Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

107 Universität Karlsruhe Institut für TelematikBearer Services Mobilkommunikation SS 1998 Telecommunication services to transfer data between access points Specification of services up to the terminal interface (OSI layers 1-3) Different data rates for voice and data (original standard) data service (circuit switched) synchronous: 2.4, 4.8 or 9.6 kbit/s asynchronous: bit/s data service (packet switched) asynchronous: bit/s Today: data rates of approx. 50 kbit/s possible – will be covered later! Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

108 Universität Karlsruhe Institut für TelematikTele Services I Mobilkommunikation SS 1998 Telecommunication services that enable voice communication via mobile phones All these basic services have to obey cellular functions, security measurements etc. Offered services mobile telephony primary goal of GSM was to enable mobile telephony offering the traditional bandwidth of 3.1 kHz Emergency number common number throughout Europe (112); mandatory for all service providers; free of charge; connection with the highest priority (preemption of other connections possible) Multinumbering several ISDN phone numbers per user possible Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

109 Universität Karlsruhe Institut für TelematikTele Services II Mobilkommunikation SS 1998 Additional services Non-Voice-Teleservices group 3 fax voice mailbox (implemented in the fixed network supporting the mobile terminals) electronic mail (MHS, Message Handling System, implemented in the fixed network) ... Short Message Service (SMS) alphanumeric data transmission to/from the mobile terminal (160 characters) using the signaling channel, thus allowing simultaneous use of basic services and SMS (almost ignored in the beginning now the most successful add-on!) Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

110 Supplementary servicesUniversität Karlsruhe Institut für Telematik Supplementary services Mobilkommunikation SS 1998 Services in addition to the basic services, cannot be offered stand-alone Similar to ISDN services besides lower bandwidth due to the radio link May differ between different service providers, countries and protocol versions Important services identification: forwarding of caller number suppression of number forwarding automatic call-back conferencing with up to 7 participants locking of the mobile terminal (incoming or outgoing calls) ... Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

111 Architecture of the GSM systemUniversität Karlsruhe Institut für Telematik Architecture of the GSM system Mobilkommunikation SS 1998 GSM is a PLMN (Public Land Mobile Network) several providers setup mobile networks following the GSM standard within each country components MS (mobile station) BS (base station) MSC (mobile switching center) LR (location register) subsystems RSS (radio subsystem): covers all radio aspects NSS (network and switching subsystem): call forwarding, handover, switching OSS (operation subsystem): management of the network Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

112 Ingredients 1: Mobile Phones, PDAs & Co.The visible but smallest part of the network! Prof. Dr.-Ing. Jochen Schiller, MC SS

113 Ingredients 2: AntennasStill visible – cause many discussions… Prof. Dr.-Ing. Jochen Schiller, MC SS

114 Ingredients 3: Infrastructure 1Base Stations Cabling Microwave links Prof. Dr.-Ing. Jochen Schiller, MC SS

115 Ingredients 3: Infrastructure 2Not „visible“, but comprise the major part of the network (also from an investment point of view…) Management Data bases Switching units Monitoring Prof. Dr.-Ing. Jochen Schiller, MC SS

116 Universität Karlsruhe Institut für TelematikGSM: overview Mobilkommunikation SS 1998 OMC, EIR, AUC fixed network HLR GMSC NSS with OSS VLR MSC VLR MSC BSC BSC RSS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

117 GSM: elements and interfacesUniversität Karlsruhe Institut für Telematik GSM: elements and interfaces Mobilkommunikation SS 1998 radio cell BSS MS MS Um radio cell MS RSS BTS BTS Abis BSC BSC A MSC MSC NSS VLR VLR signaling HLR ISDN, PSTN GMSC PDN IWF O OSS EIR AUC OMC Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

118 GSM: system architectureUniversität Karlsruhe Institut für Telematik GSM: system architecture Mobilkommunikation SS 1998 radio subsystem network and switching subsystem fixed partner networks MS MS ISDN PSTN Um MSC Abis BTS BSC EIR BTS SS7 HLR VLR BTS BSC ISDN PSTN BTS A MSC BSS IWF PSPDN CSPDN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

119 System architecture: radio subsystemUniversität Karlsruhe Institut für Telematik System architecture: radio subsystem Mobilkommunikation SS 1998 radio subsystem network and switching subsystem MS MS Components MS (Mobile Station) BSS (Base Station Subsystem): consisting of BTS (Base Transceiver Station): sender and receiver BSC (Base Station Controller): controlling several transceivers Interfaces Um : radio interface Abis : standardized, open interface with 16 kbit/s user channels A: standardized, open interface with 64 kbit/s user channels Um Abis BTS BSC MSC BTS A BTS MSC BSC BTS BSS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

120 System architecture: network and switching subsystemUniversität Karlsruhe Institut für Telematik System architecture: network and switching subsystem Mobilkommunikation SS 1998 network subsystem fixed partner networks Components MSC (Mobile Services Switching Center): IWF (Interworking Functions) ISDN (Integrated Services Digital Network) PSTN (Public Switched Telephone Network) PSPDN (Packet Switched Public Data Net.) CSPDN (Circuit Switched Public Data Net.) Databases HLR (Home Location Register) VLR (Visitor Location Register) EIR (Equipment Identity Register) ISDN PSTN MSC EIR SS7 HLR VLR ISDN PSTN MSC IWF PSPDN CSPDN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

121 Universität Karlsruhe Institut für TelematikRadio subsystem Mobilkommunikation SS 1998 The Radio Subsystem (RSS) comprises the cellular mobile network up to the switching centers Components Base Station Subsystem (BSS): Base Transceiver Station (BTS): radio components including sender, receiver, antenna - if directed antennas are used one BTS can cover several cells Base Station Controller (BSC): switching between BTSs, controlling BTSs, managing of network resources, mapping of radio channels (Um) onto terrestrial channels (A interface) BSS = BSC + sum(BTS) + interconnection Mobile Stations (MS) Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

122 Universität Karlsruhe Institut für TelematikGSM: cellular network Mobilkommunikation SS 1998 segmentation of the area into cells cell possible radio coverage of the cell idealized shape of the cell use of several carrier frequencies not the same frequency in adjoining cells cell sizes vary from some 100 m up to 35 km depending on user density, geography, transceiver power etc. hexagonal shape of cells is idealized (cells overlap, shapes depend on geography) if a mobile user changes cells  handover of the connection to the neighbor cell Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

123 GSM frequency bands Type Channels Uplink [MHz] Downlink [MHz]GSM 850 (Americas) GSM 900 classical extended 0-124, 124 channels +49 channels GSM 1800 GSM 1900 (Americas) GSM-R exclusive , 0-124 69 channels Additionally: GSM 400 (also named GSM 450 or GSM 480 at / or / MHz Please note: frequency ranges may vary depending on the country! Channels at the lower/upper edge of a frequency band are typically not used Prof. Dr.-Ing. Jochen Schiller, MC SS

124 Example coverage of GSM networks (www.gsmworld.com)Universität Karlsruhe Institut für Telematik Example coverage of GSM networks (www.gsmworld.com) Mobilkommunikation SS 1998 T-Mobile (GSM-900/1800) Germany O2 (GSM-1800) Germany AT&T (GSM-850/1900) USA Vodacom (GSM-900) South Africa Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

125 Base Transceiver Station and Base Station ControllerUniversität Karlsruhe Institut für Telematik Base Transceiver Station and Base Station Controller Mobilkommunikation SS 1998 Tasks of a BSS are distributed over BSC and BTS BTS comprises radio specific functions BSC is the switching center for radio channels Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

126 Universität Karlsruhe Institut für TelematikMobile station Mobilkommunikation SS 1998 Terminal for the use of GSM services A mobile station (MS) comprises several functional groups MT (Mobile Terminal): offers common functions used by all services the MS offers corresponds to the network termination (NT) of an ISDN access end-point of the radio interface (Um) TA (Terminal Adapter): terminal adaptation, hides radio specific characteristics TE (Terminal Equipment): peripheral device of the MS, offers services to a user does not contain GSM specific functions SIM (Subscriber Identity Module): personalization of the mobile terminal, stores user parameters R S Um TE TA MT Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

127 Network and switching subsystemUniversität Karlsruhe Institut für Telematik Network and switching subsystem Mobilkommunikation SS 1998 NSS is the main component of the public mobile network GSM switching, mobility management, interconnection to other networks, system control Components Mobile Services Switching Center (MSC) controls all connections via a separated network to/from a mobile terminal within the domain of the MSC - several BSC can belong to a MSC Databases (important: scalability, high capacity, low delay) Home Location Register (HLR) central master database containing user data, permanent and semi-permanent data of all subscribers assigned to the HLR (one provider can have several HLRs) Visitor Location Register (VLR) local database for a subset of user data, including data about all user currently in the domain of the VLR Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

128 Mobile Services Switching CenterUniversität Karlsruhe Institut für Telematik Mobile Services Switching Center Mobilkommunikation SS 1998 The MSC (mobile switching center) plays a central role in GSM switching functions additional functions for mobility support management of network resources interworking functions via Gateway MSC (GMSC) integration of several databases Functions of a MSC specific functions for paging and call forwarding termination of SS7 (signaling system no. 7) mobility specific signaling location registration and forwarding of location information provision of new services (fax, data calls) support of short message service (SMS) generation and forwarding of accounting and billing information Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

129 Universität Karlsruhe Institut für TelematikOperation subsystem Mobilkommunikation SS 1998 The OSS (Operation Subsystem) enables centralized operation, management, and maintenance of all GSM subsystems Components Authentication Center (AUC) generates user specific authentication parameters on request of a VLR authentication parameters used for authentication of mobile terminals and encryption of user data on the air interface within the GSM system Equipment Identity Register (EIR) registers GSM mobile stations and user rights stolen or malfunctioning mobile stations can be locked and sometimes even localized Operation and Maintenance Center (OMC) different control capabilities for the radio subsystem and the network subsystem Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

130 Universität Karlsruhe Institut für TelematikGSM - TDMA/FDMA Mobilkommunikation SS 1998 MHz 124 channels (200 kHz) downlink frequency MHz 124 channels (200 kHz) uplink higher GSM frame structures time GSM TDMA frame 1 2 3 4 5 6 7 8 4.615 ms GSM time-slot (normal burst) guard space guard space tail user data S Training S user data tail 3 bits 57 bits 1 26 bits 1 57 bits 3 546.5 µs 577 µs Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

131 GSM hierarchy of framesUniversität Karlsruhe Institut für Telematik GSM hierarchy of frames Mobilkommunikation SS 1998 hyperframe 1 2 ... 2045 2046 2047 3 h 28 min s superframe 1 2 ... 48 49 50 6.12 s 1 ... 24 25 multiframe 1 ... 24 25 120 ms 1 2 ... 48 49 50 235.4 ms frame 1 ... 6 7 4.615 ms slot burst 577 µs Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

132 GSM protocol layers for signalingUniversität Karlsruhe Institut für Telematik GSM protocol layers for signaling Mobilkommunikation SS 1998 Um Abis A MS BTS BSC MSC CM CM MM MM RR’ BTSM BSSAP RR BSSAP RR’ BTSM SS7 SS7 LAPDm LAPDm LAPD LAPD radio radio PCM PCM PCM PCM 16/64 kbit/s 64 kbit/s / 2.048 Mbit/s Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

133 Mobile Terminated CallUniversität Karlsruhe Institut für Telematik Mobile Terminated Call Mobilkommunikation SS 1998 1: calling a GSM subscriber 2: forwarding call to GMSC 3: signal call setup to HLR 4, 5: request MSRN from VLR 6: forward responsible MSC to GMSC 7: forward call to current MSC 8, 9: get current status of MS 10, 11: paging of MS 12, 13: MS answers 14, 15: security checks 16, 17: set up connection 4 HLR VLR 5 8 9 3 6 14 15 PSTN 7 calling station GMSC MSC 1 2 10 13 10 10 16 BSS BSS BSS 11 11 11 11 12 17 MS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

134 Mobile Originated CallUniversität Karlsruhe Institut für Telematik Mobile Originated Call Mobilkommunikation SS 1998 1, 2: connection request 3, 4: security check 5-8: check resources (free circuit) 9-10: set up call VLR 3 4 PSTN 6 5 GMSC MSC 7 8 2 9 1 MS BSS 10 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

135 Universität Karlsruhe Institut für TelematikMTC/MOC Mobilkommunikation SS 1998 BTS MS paging request channel request immediate assignment paging response authentication request authentication response ciphering command ciphering complete setup call confirmed assignment command assignment complete alerting connect connect acknowledge data/speech exchange service request MTC MOC Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

136 Universität Karlsruhe Institut für Telematik4 types of handover Mobilkommunikation SS 1998 1 2 3 4 MS MS MS MS BTS BTS BTS BTS BSC BSC BSC MSC MSC Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

137 Universität Karlsruhe Institut für TelematikHandover decision Mobilkommunikation SS 1998 receive level BTSold receive level BTSold HO_MARGIN MS MS BTSold BTSnew Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

138 Universität Karlsruhe Institut für TelematikHandover procedure Mobilkommunikation SS 1998 MS BTSold BSCold MSC BSCnew BTSnew measurement report measurement result HO decision HO required HO request resource allocation ch. activation ch. activation ack HO request ack HO command HO command HO command HO access Link establishment HO complete HO complete clear command clear command clear complete clear complete Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

139 Universität Karlsruhe Institut für TelematikSecurity in GSM Mobilkommunikation SS 1998 Security services access control/authentication user  SIM (Subscriber Identity Module): secret PIN (personal identification number) SIM  network: challenge response method confidentiality voice and signaling encrypted on the wireless link (after successful authentication) anonymity temporary identity TMSI (Temporary Mobile Subscriber Identity) newly assigned at each new location update (LUP) encrypted transmission 3 algorithms specified in GSM A3 for authentication (“secret”, open interface) A5 for encryption (standardized) A8 for key generation (“secret”, open interface) “secret”: A3 and A8 available via the Internet network providers can use stronger mechanisms Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

140 Universität Karlsruhe Institut für TelematikGSM - authentication Mobilkommunikation SS 1998 SIM mobile network RAND Ki RAND RAND Ki 128 bit 128 bit 128 bit 128 bit AC A3 A3 SIM SRES* 32 bit SRES bit SRES* =? SRES SRES MSC SRES 32 bit Ki: individual subscriber authentication key SRES: signed response Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

141 GSM - key generation and encryptionUniversität Karlsruhe Institut für Telematik GSM - key generation and encryption Mobilkommunikation SS 1998 mobile network (BTS) MS with SIM RAND Ki RAND RAND Ki AC SIM 128 bit 128 bit 128 bit 128 bit A8 A8 cipher key Kc 64 bit Kc 64 bit data encrypted data SRES data BSS MS A5 A5 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

142 Universität Karlsruhe Institut für TelematikData services in GSM I Mobilkommunikation SS 1998 Data transmission standardized with only 9.6 kbit/s advanced coding allows 14,4 kbit/s not enough for Internet and multimedia applications HSCSD (High-Speed Circuit Switched Data) mainly software update bundling of several time-slots to get higher AIUR (Air Interface User Rate) (e.g., 57.6 kbit/s using 4 slots, 14.4 each) advantage: ready to use, constant quality, simple disadvantage: channels blocked for voice transmission Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

143 Universität Karlsruhe Institut für TelematikData services in GSM II Mobilkommunikation SS 1998 GPRS (General Packet Radio Service) packet switching using free slots only if data packets ready to send (e.g., 50 kbit/s using 4 slots temporarily) standardization 1998, introduction 2001 advantage: one step towards UMTS, more flexible disadvantage: more investment needed (new hardware) GPRS network elements GSN (GPRS Support Nodes): GGSN and SGSN GGSN (Gateway GSN) interworking unit between GPRS and PDN (Packet Data Network) SGSN (Serving GSN) supports the MS (location, billing, security) GR (GPRS Register) user addresses Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

144 GPRS quality of serviceUniversität Karlsruhe Institut für Telematik GPRS quality of service Mobilkommunikation SS 1998 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

145 Examples for GPRS device classesReceiving slots Sending slots Maximum number of slots 1 2 3 5 4 8 10 12 Prof. Dr.-Ing. Jochen Schiller, MC SS

146 GPRS user data rates in kbit/sCoding scheme 1 slot 2 slots 3 slots 4 slots 5 slots 6 slots 7 slots 8 slots CS-1 9.05 18.1 27.15 36.2 45.25 54.3 63.35 72.4 CS-2 13.4 26.8 40.2 53.6 67 80.4 93.8 107.2 CS-3 15.6 31.2 46.8 62.4 78 93.6 109.2 124.8 CS-4 21.4 42.8 64.2 85.6 107 128.4 149.8 171.2 Prof. Dr.-Ing. Jochen Schiller, MC SS

147 GPRS architecture and interfacesUniversität Karlsruhe Institut für Telematik GPRS architecture and interfaces Mobilkommunikation SS 1998 MS BSS GGSN SGSN MSC Um EIR HLR/ GR VLR PDN Gb Gn Gi Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

148 GPRS protocol architectureUniversität Karlsruhe Institut für Telematik GPRS protocol architecture Mobilkommunikation SS 1998 MS BSS SGSN GGSN Um Gb Gn Gi apps. IP/X.25 IP/X.25 SNDCP SNDCP GTP GTP LLC LLC UDP/TCP UDP/TCP RLC RLC BSSGP BSSGP IP IP MAC MAC FR FR L1/L2 L1/L2 radio radio Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

149 Universität Karlsruhe Institut für TelematikDECT Mobilkommunikation SS 1998 DECT (Digital European Cordless Telephone) standardized by ETSI (ETS x) for cordless telephones standard describes air interface between base-station and mobile phone DECT has been renamed for international marketing reasons into „Digital Enhanced Cordless Telecommunication“ Characteristics frequency: MHz channels: 120 full duplex duplex mechanism: TDD (Time Division Duplex) with 10 ms frame length multplexing scheme: FDMA with 10 carrier frequencies, TDMA with 2x 12 slots modulation: digital, Gaußian Minimum Shift Key (GMSK) power: 10 mW average (max. 250 mW) range: approx. 50 m in buildings, 300 m open space Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

150 DECT system architecture reference modelUniversität Karlsruhe Institut für Telematik DECT system architecture reference model Mobilkommunikation SS 1998 D4 D3 VDB D2 PA PT FT local network HDB PA PT D1 global network FT local network Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

151 Universität Karlsruhe Institut für TelematikDECT reference model Mobilkommunikation SS 1998 C-Plane U-Plane close to the OSI reference model management plane over all layers several services in C(ontrol)- and U(ser)-plane signaling, interworking application processes network layer OSI layer 3 management data link control data link control OSI layer 2 medium access control physical layer OSI layer 1 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

152 Universität Karlsruhe Institut für TelematikDECT layers I Mobilkommunikation SS 1998 Physical layer modulation/demodulation generation of the physical channel structure with a guaranteed throughput controlling of radio transmission channel assignment on request of the MAC layer detection of incoming signals sender/receiver synchronization collecting status information for the management plane MAC layer maintaining basic services, activating/deactivating physical channels multiplexing of logical channels e.g., C: signaling, I: user data, P: paging, Q: broadcast segmentation/reassembly error control/error correction Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

153 DECT time multiplex frameUniversität Karlsruhe Institut für Telematik DECT time multiplex frame Mobilkommunikation SS 1998 1 frame = 10 ms 12 down slots 12 up slots slot guard 420 bit + 52 µs guard time („60 bit“) in ms 419 sync D field 31 387 A: network control B: user data X: transmission quality A field B field X field 63 319 3 protected mode DATA 64 C 16 DATA 64 C 16 DATA 64 C 16 DATA 64 C 16 25.6 kbit/s simplex bearer unprotected mode 32 kbit/s DATA Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

154 Universität Karlsruhe Institut für TelematikDECT layers II Mobilkommunikation SS 1998 Data link control layer creation and keeping up reliable connections between the mobile terminal and basestation two DLC protocols for the control plane (C-Plane) connectionless broadcast service: paging functionality Lc+LAPC protocol: in-call signaling (similar to LAPD within ISDN), adapted to the underlying MAC service several services specified for the user plane (U-Plane) null-service: offers unmodified MAC services frame relay: simple packet transmission frame switching: time-bounded packet transmission error correcting transmission: uses FEC, for delay critical, time-bounded services bandwidth adaptive transmission „Escape“ service: for further enhancements of the standard Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

155 Universität Karlsruhe Institut für TelematikDECT layers III Mobilkommunikation SS 1998 Network layer similar to ISDN (Q.931) and GSM (04.08) offers services to request, check, reserve, control, and release resources at the basestation and mobile terminal resources necessary for a wireless connection necessary for the connection of the DECT system to the fixed network main tasks call control: setup, release, negotiation, control call independent services: call forwarding, accounting, call redirecting mobility management: identity management, authentication, management of the location register Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

156 Enhancements of the standardUniversität Karlsruhe Institut für Telematik Enhancements of the standard Mobilkommunikation SS 1998 Several „DECT Application Profiles“ in addition to the DECT specification GAP (Generic Access Profile) standardized by ETSI in 1997 assures interoperability between DECT equipment of different manufacturers (minimal requirements for voice communication) enhanced management capabilities through the fixed network: Cordless Terminal Mobility (CTM) DECT/GSM Interworking Profile (GIP): connection to GSM ISDN Interworking Profiles (IAP, IIP): connection to ISDN Radio Local Loop Access Profile (RAP): public telephone service CTM Access Profile (CAP): support for user mobility DECT basestation GAP Common Air Interface Portable Part fixed network Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

157 TETRA - Terrestrial Trunked RadioUniversität Karlsruhe Institut für Telematik TETRA - Terrestrial Trunked Radio Mobilkommunikation SS 1998 Trunked radio systems many different radio carriers assign single carrier for a short period to one user/group of users taxi service, fleet management, rescue teams interfaces to public networks, voice and data services very reliable, fast call setup, local operation TETRA - ETSI standard formerly: Trans European Trunked Radio point-to-point and point-to-multipoint encryption (end-to-end, air interface), authentication of devices, users and networks group call, broadcast, sub-second group-call setup ad-hoc (“direct mode”), relay and infrastructure networks call queuing with pre-emptive priorities Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

158 TETRA – Contracts by Sector (percentage)Used in over 70 countries, more than 20 device manufacturers Prof. Dr.-Ing. Jochen Schiller, MC SS

159 TETRA – Network ArchitectureTETRA infrastructure PSTN, ISDN, Internet, PDN switch NMS switch switch BS ISI other TETRA networks BS AI BS AI: Air Interface BS: Base Station DMO: Direct Mode Operation ISI: Inter-System Interface NMS: Network Management System PEI: Peripheral Equipment Interface DMO PEI Prof. Dr.-Ing. Jochen Schiller, MC SS

160 TETRA – Direct Mode I Direct Mode enables ad-hoc operation and is one of the most important differences to pure infrastructure-based networks such as GSM, cdma2000 or UMTS. network Individual Call “Dual Watch” – alternating participation in Infrastructure and ad-hoc network Authorizing mobile station Group Call Managed Direct Mode Prof. Dr.-Ing. Jochen Schiller, MC SS

161 TETRA – Direct Mode II An additional repeater may increase the transmission range (e.g. police car) network Direct Mode with Repeater Direct Mode with Gateway network network Authorizing Repeater Managed Repeater/Gateway Direct Mode with Repeater/Gateway Prof. Dr.-Ing. Jochen Schiller, MC SS

162 TETRA – Technology Services FrequenciesVoice+Data (V+D) and Packet Data Optimized (PDO) Short data service (SDS) Frequencies Duplex: FDD, Modulation: DQPSK Europe (in MHz, not all available yet) UL / DL; UL / DL, UL / DL; UL / DL Other countries UL / DL; UL / DL, UL / DL Prof. Dr.-Ing. Jochen Schiller, MC SS

163 TDMA structure of the voice+data systemUniversität Karlsruhe Institut für Telematik TDMA structure of the voice+data system Mobilkommunikation SS 1998 hyperframe 1 2 ... 57 58 59 61.2 s multiframe 1 2 ... 15 16 17 1.02 s CF frame Control Frame 1 2 3 56.67 ms slot 14.17 ms Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

164 TETRA – Data Rates Infrastructure mode, V+D in kbit/sNo. of time slots No protection Low protection High protection TETRA Release 2 – Supporting higher data rates TEDS (TETRA Enhanced Data Service) up to 100 kbit/s backward compatibility Prof. Dr.-Ing. Jochen Schiller, MC SS

165 Universität Karlsruhe Institut für TelematikUMTS and IMT-2000 Mobilkommunikation SS 1998 Proposals for IMT-2000 (International Mobile Telecommunications) UWC-136, cdma2000, WP-CDMA UMTS (Universal Mobile Telecommunications System) from ETSI UMTS UTRA (was: UMTS, now: Universal Terrestrial Radio Access) enhancements of GSM EDGE (Enhanced Data rates for GSM Evolution): GSM up to 384 kbit/s CAMEL (Customized Application for Mobile Enhanced Logic) VHE (virtual Home Environment) fits into GMM (Global Multimedia Mobility) initiative from ETSI requirements min. 144 kbit/s rural (goal: 384 kbit/s) min. 384 kbit/s suburban (goal: 512 kbit/s) up to 2 Mbit/s urban Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

166 Universität Karlsruhe Institut für TelematikFrequencies for IMT-2000 Mobilkommunikation SS 1998 1850 1900 1950 2000 2050 2100 2150 2200 MHz ITU allocation (WRC 1992) IMT-2000 MSS  IMT-2000 MSS  GSM 1800 DE CT T D UTRA FDD  MSS  T D UTRA FDD  MSS  Europe GSM 1800 IMT-2000 MSS  IMT-2000 MSS  China PHS cdma2000 W-CDMA MSS  cdma2000 W-CDMA MSS  Japan PCS MSS  rsv. MSS  North America 1850 1900 1950 2000 2050 2100 2150 2200 MHz Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

167 Universität Karlsruhe Institut für TelematikIMT-2000 family Mobilkommunikation SS 1998 Interface for Internetworking IMT-2000 Core Network ITU-T GSM (MAP) ANSI-41 (IS-634) IP-Network Flexible assignment of Core Network and Radio Access Initial UMTS (R99 w/ FDD) IMT-DS (Direct Spread) UTRA FDD (W-CDMA) 3GPP IMT-TC (Time Code) UTRA TDD (TD-CDMA); TD-SCDMA 3GPP IMT-MC (Multi Carrier) cdma2000 3GPP2 IMT-SC (Single Carrier) UWC-136 (EDGE) UWCC/3GPP IMT-FT (Freq. Time) DECT ETSI IMT-2000 Radio Access ITU-R Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

168 Freeze date (indicative only)GSM and UMTS Releases GSM/EDGE Release 3G Release Abbreviated name Spec version number Freeze date (indicative only) Phase 2+ Release 6 Release 6 Rel-6 6.x.y December March 2005 Phase 2+ Release 5 Release 5 Rel-5 5.x.y March - June 2002 Phase 2+ Release 4 Release 4 Rel-4 4.x.y March 2001 - Release 2000 R00 Renaming… Phase 2+ Release 2000 9.x.y Release 1999 R99 3.x.y March 2000 Phase 2+ Release 1999 8.x.y Phase 2+ Release 1998 R98 7.x.y early 1999 Phase 2+ Release 1997 R97 early 1998 Phase 2+ Release 1996 R96 early 1997 Phase 2 Ph2 1995 Phase 1 Ph1 1992 Prof. Dr.-Ing. Jochen Schiller, MC SS

169 Licensing Example: UMTS in Germany, 18. August 2000Universität Karlsruhe Institut für Telematik Licensing Example: UMTS in Germany, 18. August 2000 Mobilkommunikation SS 1998 UTRA-FDD: Uplink MHz Downlink MHz duplex spacing 190 MHz 12 channels, each 5 MHz UTRA-TDD: MHz, MHz; 5 MHz channels Coverage of the population 25% until 12/2003 50% until 12/2005 Sum: billion € Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

170 UMTS architecture (Release 99 used here!)Universität Karlsruhe Institut für Telematik UMTS architecture (Release 99 used here!) Mobilkommunikation SS 1998 UTRAN (UTRA Network) Cell level mobility Radio Network Subsystem (RNS) Encapsulation of all radio specific tasks UE (User Equipment) CN (Core Network) Inter system handover Location management if there is no dedicated connection between UE and UTRAN Uu Iu UE UTRAN CN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

171 UMTS domains and interfaces IUniversität Karlsruhe Institut für Telematik UMTS domains and interfaces I Mobilkommunikation SS 1998 User Equipment Domain Assigned to a single user in order to access UMTS services Infrastructure Domain Shared among all users Offers UMTS services to all accepted users Home Network Domain Zu Cu Uu Iu Yu USIM Domain Mobile Equipment Domain Access Network Domain Serving Network Domain Transit Network Domain Core Network Domain User Equipment Domain Infrastructure Domain Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

172 UMTS domains and interfaces IIUniversität Karlsruhe Institut für Telematik UMTS domains and interfaces II Mobilkommunikation SS 1998 Universal Subscriber Identity Module (USIM) Functions for encryption and authentication of users Located on a SIM inserted into a mobile device Mobile Equipment Domain Functions for radio transmission User interface for establishing/maintaining end-to-end connections Access Network Domain Access network dependent functions Core Network Domain Access network independent functions Serving Network Domain Network currently responsible for communication Home Network Domain Location and access network independent functions Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

173 Spreading and scrambling of user dataUniversität Karlsruhe Institut für Telematik Spreading and scrambling of user data Mobilkommunikation SS 1998 Constant chipping rate of 3.84 Mchip/s Different user data rates supported via different spreading factors higher data rate: less chips per bit and vice versa User separation via unique, quasi orthogonal scrambling codes users are not separated via orthogonal spreading codes much simpler management of codes: each station can use the same orthogonal spreading codes precise synchronisation not necessary as the scrambling codes stay quasi-orthogonal data1 data2 data3 data4 data5 spr. code1 spr. code2 spr. code3 spr. code1 spr. code4 scrambling code1 scrambling code2 sender1 sender2 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

174 OSVF coding 1,1,1,1,1,1,1,1 1,1,1,1 ... 1,1,1,1,-1,-1,-1,-1 1,1 1,1,-1,-1,1,1,-1,-1 ... 1,1,-1,-1 X,X 1,1,-1,-1,-1,-1,1,1 1 X 1,-1,1,-1,1,-1,1,-1 X,-X ... 1,-1,1,-1 1,-1,1,-1,-1,1,-1,1 1,-1 SF=n SF=2n 1,-1,-1,1,1,-1,-1,1 ... 1,-1,-1,1 1,-1,-1,1,-1,1,1,-1 SF=1 SF=2 SF=4 SF=8 Prof. Dr.-Ing. Jochen Schiller, MC SS

175 UMTS FDD frame structureUniversität Karlsruhe Institut für Telematik UMTS FDD frame structure Mobilkommunikation SS 1998 W-CDMA MHz uplink MHz downlink chipping rate: Mchip/s soft handover QPSK complex power control (1500 power control cycles/s) spreading: UL: 4-256; DL:4-512 Radio frame 10 ms 1 2 ... 12 13 14 Time slot 666.7 µs Pilot TFCI FBI TPC uplink DPCCH 2560 chips, 10 bits 666.7 µs Data uplink DPDCH 2560 chips, 10*2k bits (k = 0...6) 666.7 µs Data1 TPC TFCI Data2 Pilot downlink DPCH FBI: Feedback Information TPC: Transmit Power Control TFCI: Transport Format Combination Indicator DPCCH: Dedicated Physical Control Channel DPDCH: Dedicated Physical Data Channel DPCH: Dedicated Physical Channel DPDCH DPCCH DPDCH DPCCH 2560 chips, 10*2k bits (k = 0...7) Slot structure NOT for user separation but synchronisation for periodic functions! Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

176 Typical UTRA-FDD uplink data ratesUser data rate [kbit/s] 12.2 (voice) 64 144 384 DPDCH [kbit/s] 60 240 480 960 DPCCH [kbit/s] 15 Spreading 16 8 4 Prof. Dr.-Ing. Jochen Schiller, MC SS

177 UMTS TDD frame structure (burst type 2)Universität Karlsruhe Institut für Telematik UMTS TDD frame structure (burst type 2) Mobilkommunikation SS 1998 Radio frame 10 ms 1 2 ... 12 13 14 Time slot 666.7 µs Data 1104 chips Midample 256 chips Data 1104 chips GP Traffic burst GP: guard period 96 chips 2560 chips TD-CDMA 2560 chips per slot spreading: 1-16 symmetric or asymmetric slot assignment to UL/DL (min. 1 per direction) tight synchronisation needed simpler power control ( power control cycles/s) Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

178 Universität Karlsruhe Institut für TelematikUTRAN architecture Mobilkommunikation SS 1998 RNS RNC: Radio Network Controller RNS: Radio Network Subsystem UE1 Node B Iub Iu RNC CN UE2 Node B Node B UTRAN comprises several RNSs Node B can support FDD or TDD or both RNC is responsible for handover decisions requiring signalingto the UE Cell offers FDD or TDD UE3 Iur Node B Iub Node B RNC Node B Node B RNS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

179 Universität Karlsruhe Institut für TelematikUTRAN architecture Mobilkommunikation SS 1998 RNS RNC: Radio Network Controller RNS: Radio Network Subsystem UE Node B Iub UTRAN comprises several RNSs Node B can support FDD or TDD or both RNC is responsible for handover decisions requiring signaling to the UE Cell offers FDD or TDD RNC Iu Node B Node B CN Iur Node B Iub Node B RNC Node B Node B RNS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

180 Universität Karlsruhe Institut für TelematikUTRAN functions Mobilkommunikation SS 1998 Admission control Congestion control System information broadcasting Radio channel encryption Handover SRNS moving Radio network configuration Channel quality measurements Macro diversity Radio carrier control Radio resource control Data transmission over the radio interface Outer loop power control (FDD and TDD) Channel coding Access control Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

181 Core network: protocolsUniversität Karlsruhe Institut für Telematik Core network: protocols Mobilkommunikation SS 1998 VLR PSTN/ ISDN MSC GMSC GSM-CS backbone RNS HLR RNS PDN (X.25), Internet (IP) SGSN GGSN Layer 3: IP GPRS backbone (IP) Layer 2: ATM SS 7 Layer 1: PDH, SDH, SONET UTRAN CN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

182 Core network: architectureUniversität Karlsruhe Institut für Telematik Core network: architecture Mobilkommunikation SS 1998 VLR BSS BTS Abis Iu BSC MSC GMSC PSTN Node B BTS IuCS AuC EIR HLR GR Node B Iub Node B RNC SGSN GGSN Gi Gn Node B Node B IuPS CN RNS Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

183 Universität Karlsruhe Institut für TelematikCore network Mobilkommunikation SS 1998 The Core Network (CN) and thus the Interface Iu, too, are separated into two logical domains: Circuit Switched Domain (CSD) Circuit switched service incl. signaling Resource reservation at connection setup GSM components (MSC, GMSC, VLR) IuCS Packet Switched Domain (PSD) GPRS components (SGSN, GGSN) IuPS Release 99 uses the GSM/GPRS network and adds a new radio access! Helps to save a lot of money … Much faster deployment Not as flexible as newer releases (5, 6) Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

184 UMTS protocol stacks (user plane)Universität Karlsruhe Institut für Telematik UMTS protocol stacks (user plane) Mobilkommunikation SS 1998 UE Uu UTRAN IuCS 3G MSC apps. & protocols Circuit switched RLC RLC SAR SAR MAC MAC AAL2 AAL2 radio radio ATM ATM UE Uu UTRAN IuPS 3G SGSN Gn 3G GGSN apps. & protocols IP, PPP, … IP tunnel IP, PPP, … Packet switched PDCP PDCP GTP GTP GTP GTP RLC RLC UDP/IP UDP/IP UDP/IP UDP/IP MAC MAC AAL5 AAL5 L2 L2 radio radio ATM ATM L1 L1 Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

185 Support of mobility: macro diversityUniversität Karlsruhe Institut für Telematik Support of mobility: macro diversity Mobilkommunikation SS 1998 Multicasting of data via several physical channels Enables soft handover FDD mode only Uplink simultaneous reception of UE data at several Node Bs Reconstruction of data at Node B, SRNC or DRNC Downlink Simultaneous transmission of data via different cells Different spreading codes in different cells UE Node B Node B RNC CN Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

186 Support of mobility: handoverUniversität Karlsruhe Institut für Telematik Support of mobility: handover Mobilkommunikation SS 1998 From and to other systems (e.g., UMTS to GSM) This is a must as UMTS coverage will be poor in the beginning RNS controlling the connection is called SRNS (Serving RNS) RNS offering additional resources (e.g., for soft handover) is called Drift RNS (DRNS) End-to-end connections between UE and CN only via Iu at the SRNS Change of SRNS requires change of Iu Initiated by the SRNS Controlled by the RNC and CN Node B SRNC CN Iub Iu UE Iur Node B DRNC Iub Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

187 Example handover types in UMTS/GSMUE1 Node B1 RNC1 3G MSC1 Iu UE2 Node B2 Iub Iur UE3 Node B3 RNC2 3G MSC2 UE4 BTS BSC 2G MSC3 Abis A Prof. Dr.-Ing. Jochen Schiller, MC SS

188 Breathing Cells GSM UMTSMobile device gets exclusive signal from the base station Number of devices in a cell does not influence cell size UMTS Cell size is closely correlated to the cell capacity Signal-to-nose ratio determines cell capacity Noise is generated by interference from other cells other users of the same cell Interference increases noise level Devices at the edge of a cell cannot further increase their output power (max. power limit) and thus drop out of the cell  no more communication possible Limitation of the max. number of users within a cell required Cell breathing complicates network planning Prof. Dr.-Ing. Jochen Schiller, MC SS

189 Breathing Cells: ExampleProf. Dr.-Ing. Jochen Schiller, MC SS

190 UMTS services (originally)Universität Karlsruhe Institut für Telematik UMTS services (originally) Mobilkommunikation SS 1998 Data transmission service profiles Virtual Home Environment (VHE) Enables access to personalized data independent of location, access network, and device Network operators may offer new services without changing the network Service providers may offer services based on components which allow the automatic adaptation to new networks and devices Integration of existing IN services Circuit switched 16 kbit/s Voice SMS successor, Packet switched 14.4 kbit/s Simple Messaging Switched Data asymmetrical, MM, downloads 384 kbit/s Medium MM Low coverage, max. 6 km/h 2 Mbit/s High MM Bidirectional, video telephone 128 kbit/s High Interactive MM Transport mode Bandwidth Service Profile Prof. Dr.-Ing. Jochen Schiller, MC SS Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

191 Example 3G Networks: JapanFOMA (Freedom Of Mobile multimedia Access) in Japan Examples for FOMA phones Prof. Dr.-Ing. Jochen Schiller, MC SS

192 Example 3G networks: Australiacdma2000 1xEV-DO in Melbourne/Australia Examples for 1xEV-DO devices Prof. Dr.-Ing. Jochen Schiller, MC SS

193 Isle of Man – Start of UMTS in Europe as TestProf. Dr.-Ing. Jochen Schiller, MC SS

194 UMTS in Monaco Prof. Dr.-Ing. Jochen Schiller, MC SS

195 UMTS in Europe Orange/UK Vodafone/GermanyProf. Dr.-Ing. Jochen Schiller, MC SS

196 Some current enhancementsGSM EMS/MMS EMS: 760 characters possible by chaining SMS, animated icons, ring tones, was soon replaced by MMS (or simply skipped) MMS: transmission of images, video clips, audio see WAP 2.0 / chapter 10 EDGE (Enhanced Data Rates for Global [was: GSM] Evolution) 8-PSK instead of GMSK, up to 384 kbit/s new modulation and coding schemes for GPRS  EGPRS MCS-1 to MCS-4 uses GMSK at rates 8.8/11.2/14.8/17.6 kbit/s MCS-5 to MCS-9 uses 8-PSK at rates 22.4/29.6/44.8/54.4/59.2 kbit/s UMTS HSDPA (High-Speed Downlink Packet Access) initially up to 10 Mbit/s for the downlink, later on 20 Mbit/s using MIMO- (Multiple Input Multiple Output-) antennas uses 16-QAM instead of QPSK Prof. Dr.-Ing. Jochen Schiller, MC SS