1 Mobile Ad-hoc Network (MANET) PropertiesPROPERTIES OF MANET • Seamless interaction and ubiquitous mobile computing environment • Neighbor discovery─ One of the important characteristics of a MANET node • Data routing abilities ─ data can be routed from a source node to a neighboring node • Flexible network architecture and variable routing paths ─ to provide communication in case of the limited wireless connectivity range and resource constraints • Flexibility─ enables fast establishment of networks

2 When a new network is to be established, the only requirement is to provide a new set of nodes with limited wireless communication range A node has limited capability, that is, it can connect only to the nodes which are nearbyand thus consumes limited power Peer-to-Peer connectivity Computations decentralization─independent computational, switching (or routing), and communication capabilities Weak connectivity and remote server latency Unreliable links to base station or gateway ─ failure of an intermediate node results in greater latency in communicating with the remote server Resource constraints─ Limited bandwidth available between two intermediate nodes Node may have limited power and thus computations need to be energy-efficient No need of access-point

3 Need to solve exposed or hidden terminal problem Diversity in nodes─ iPods, palm handheld computers, Smartphones, PCs, smart labels, smart sensors, and automobile-embedded systems Protocol diversity─ Nodes can use different protocols, for example, IrDA, Bluetooth, ZigBee, , GSM, or TCP/IP Data caching, saving, and aggregation at node Bandwidth of an access-point-based fixed infrastructure network • Large number devices connects to a centralized server • The bandwidth requirement too high • Using TDMA and SDMA, the bandwidth (spectrum) requirement is reduced

4 • A node itself ─ a router for all the packets coming from or going Spectrum requirement at Nodes in MANET • A node itself ─ a router for all the packets coming from or going to the other nodes • Node D at a given instant─ Can get incoming packets from E, F, G, and A and can send packets to C and A or vice versa

5 Each node has low and adaptable transmission power• Nodes are themselves mobile • Therefore, bandwidth available to any node at any instant is variable • MANET enables spectrum reuse • MANET communication is multi-hop • When node D transmits to G, it is through the three hops (i) D - -E, (ii) E - -F, and (iii) F - -G. Each node has low and adaptable transmission power • Hops can therefore occur simultaneously using the same frequency band • There is spatial reuse of bandwidth • Also, the bandwidth depends on surrounding environment

6 Bandwidth Need computations• Assume FDMA mode access by a node • The bandwidth depends on the number of next hop neighbours • The node with higher number of next hop neighbours require higher bandwidth in FDMA • The nodes D, E, and G shall need higher bandwidth compared to C and F • Bandwidth required will be 2 × 3 × fbw0 when three nodes D, E, or G can transmit in full duplex mode to all the nodes • Will be 2 × 2 × fbw0 for two nodes C or F Summary • Protocol diversity • Nodes diversity • Weak connectivity • MANET node’s Neighbor discovery • Data routing abilities • Flexible network architecture • Variable routing paths to provide communication • Limited wireless connectivity range and resource constraints

7 Mobile Ad-hoc Network (MANET) ApplicationsContent Distribution and Synchronization • In an enterprise, there are a number of Bluetooth-enabled mobile handheld devices, PCs, laptops, and WiFi access points • MANET used for content- distribution, PIM, other information dissemination, information fusion, and file sharing in the enterprise MANET nodes in multicast tree topology • Disseminate data packets and form a multicasting network • Clusters of the nodes used to give amulticast tree topology in a MANET Mesh Network • A multicast tree network differs from mesh as it provides only a single path between a sender and a receiver • Mesh network many paths

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9 Protocol for unified multicasting through announcements (PUMA)A protocol that builds a mesh that connects MANET nodes with each other On the other mesh provides multiple paths between sender and receiver nodes Needs for PUMA • MANETs have nodes which may be mobile and the wireless links are error prone • Certain packets may not be delivered to receivers through a multicast tree topology • In such situations PUMA is able to reduce the redundancy • PUMA adapts the amount of redundancy in the network depending on need

10 Image Acquisition, Processing and Distribution using MANET Number of imaging devices forming a MANET - low cost digital still camera with a wireless network interface, Wireless WebCam, mobile device connected to a digital still camera, mobile phones, and pocket PCs equipped with an image acquisition sensor Applications of Image Acquisition using MANET • Remote viewfinder by security personals in an office • Image file transfer • Messaging and data transmission to remote devices using b • Remote controlling

11 Mobile Ad-hoc Network (MANET) Routing AlgorithmsDynamic Source Routing (DSR) Protocol Deploys source routing Source routing means that each data packet includes the routing-node addresses also Performs unicast routing Unicast means routing packets to a single destined address DSR Nodes Each node caches the specified route to destination during source routing of a packet through that node This enables a node to provide route specification when a packet source routes from that node Each node deletes the specified route to destination during routing of error packet in reverse path to the source in case of observing a disconnection during forward path to destination The deletion of link shown in a table or cache is called link reversal

12 Phase 1 in DSR Protocol • Source node initiates a route discovery process • It broadcasts the packets, each with a header • It then expects return of acknowledgement from each destination • The packets are called route request (RREQ) packets • DSR uses flooding (sends multiple RREQs • A header for each route request packet has the unique request number and source and destination addresses • This enables identification of request at each intermediate node in the request and acknowledged packet(s) • When the process starts, initially only the source address is given in the header • When the packet reaches a neighbour, that is, any intermediate node, the node adds its own address in the header if it is able to successfully send the packet to its next neighbour • When the packet reaches the destined address, its header therefore has all addresses of the nodes in the path

13 Example • Assume that node D is a source and G is a destination and the path D—E—F--G is not known. In such a case the path cannot be placed in the header

14 Source routing addresses in DSR Node Destination Cached PathSource Route Discovery Process • Source header from D puts the sequence number q and source address D in the packet header and sends the packet to its next neighbour. When the packet reaches E, its header is (q, D) • Assume that no route error packet bounced back from neighbour E • The packet is then transmitted to F • When the packet reaches F, its header is (q, D, E). Assume that no route error packet bounced back from neighbour F • The packet is transmitted from F to G. Assume that no route error packet bounced back from neighbour G. • When the packet reaches G, its header is (q, D, E, F) Source routing addresses in DSR • Assuming that there is a message from a MANET node D in the network Node Destination Cached Path D A D—C--A D B D----C---A---B D F D---E---F D G D---E---F---G

15 Ad-hoc On-demand Distance Vector (AODV) Routing protocol• A reactive protocol • Reacts to the changes and maintains only the active routes in the caches or tables for a pre-specified expiration time • Routes that are found that are available at a given instant • Performs unicast routing • Distance vector means a set of distant nodes, which defines the path to destination • D—E—F--G is a distance vector for source-destination pair D and G • In AODV, a distance vector is provided on demand during forwarding of a packet to destination by a node in the path and not by the route cache providing path through the header in the source data packet [phase] • Every node keeps a next-hop routing table, which contains the destinations to which it currently has a route • A routing table entry expires if it has not been used or reactivated for a prespecified expiration time • AODV adopts the destination sequence number technique • Does not deploy flooding (multiple RREQs) • Stores the next hop routing information of the active routes in the routing caches (tables) at each node • Therefore, has small header size and thus reduces the network traffic overhead

16 Phase in AODV Protocol • Source node initiates a route discovery process if no route is available in the routing table • It broadcasts the demand through the RREQ packets • Each RREQ has an ID and the addresses of the source and destination in its header • It expects return acknowledgement from destination • A node identifies the last observed sequence number of the destination from the ID • Each RREQ starts with a small TTL (time to live) value [Number of attempts] • If the destination is not found during the TTL, the TTL is increased in subsequent RREQ packets • The node also identifies sequence number of source node • Sequence numbers ensure loop-free and up-to-date routes. • Loop-free means free from bouncing of a packet to a node after intermediate hops • Each node rejects the RREQ which it had observed before • This reduces flooding which means it reduces too many RREQs present in the network at a given instant

17 Route table in AODV • Keep entries for a specified period and each node maintains a cache • The cache saves the received RREQs • Only the RREQ of highest sequence numbers are accepted and previous ones are discarded • The cache also saves the return path for each RREQ source • When a node having a route to the destination or the destined node receives the RREQ, it checks the destination sequence number it currently knows and the one specified in the RREQ • RREP packet is created and forwarded back to the source only if the destination sequence number is equal to or greater than the one specified in RREQ • It guarantees the up-dation of routing cache information

18 Temporally ordered routing algorithm (TORA)• A reactive protocol • Reacts to the changes and link reversals • Employed for highly dynamic MANETs and provides an improved partial link reversal process • Discovers the network portions showing the link reversal(s) • Has a feature that it stops the nonproductive link reversals in a given portion of the network • Assumes addresses of the routers in the path and of source and destination for one set of input route • Each node provides only one set of subsequent route addresses • Possesses network capacity such that many nodes can send packets to a given destination • Guarantees loop-free routes and supports multicasting (from one source to multiple destinations) • Unlike AODV, but similar to DSR, TORA supports unidirectional links and also provides multiple routing paths • It does not exchange hello messages periodically to listen to disconnected links as done by AODV

19 Cluster-head gateway switch routing (CGSR)• A hierarchical routing protocol • proactive protocol • When a source routes the packets to destination, the routing tables are already available at the nodes • A cluster higher in hierarchy sends the packets to the cluster lower in hierarchy • Each cluster can have several daughters and forms a tree-like structure in CGSR • Forms a cluster structure • The nodes aggregate into clusters using an appropriate algorithm • The different clusters can be assigned to different band of frequencies in FDMA or different spreading CDMA codes CGSR algorithm • Defines a cluster-head, the node used for connection to other clusters • Also defines a gateway node which provides switching (communication) between two or more cluster-heads

20 Three types of nodes in CGSRInternal nodes in a cluster which transmit and receive the messages and packets through a cluster-head 2. Cluster-head in each cluster such that there is a cluster-head which dynamically schedules the route paths. It controls a group of ad-hoc hosts, monitors broadcasting within the cluster, and forwards the messages to another cluster-head3 3. Gateway node to carry out transmission and reception of messages and packets between cluster-heads of two clusters Cluster structure • A higher performance of the routing protocol as compared to other protocols because it provides gateway switch-type traffic redirections and clusters provide an effective membership of nodes for connectivity Phases 1, 2, and 3 of CGSR • Routing path discovery and caching, maintaining update, and distribution, respectively • The basic processes of CGSR are cluster definitions and selection of clusters for routing • Algorithms are used for both the processes

21 Summary Optimized Link State Routing Protocol (OLSR)• Characteristics similar to those of link state flat routing table driven protocol, but in this case, only required updates are sent to the routing database • Reduces the overhead control packet size and numbers • Further, there are multi-point nodes for relay of data • A node selects independently a multi-point node which also relays the route tables • The node provides bi-directional links such that the routes provided by the multi- point relay routing neigh bouring node is also taken into account Summary • TORA─ A reactive protocol, Reacts to the changes and link reversals, Employed for highly dynamic MANETs and provides an improved partial link reversal process • CGSR ─A hierarchical routing protocol, proactive protocol, When a source routes the packets to destination, the routing tables are already available at the nodes • Optimized Link State Reversal

22 Mobile Devices and SystemsHandheld Pocket Computers and Mobile System Operating Systems

23 Handheld Pocket ComputersCome in many manifestations For example, the smart phone Pocket-sized PCs Differ from smart phones and multimedia phones in that that they can be programmed for customized applications

24 Handheld Pocket ComputersOffer a variety of application and programming tools not included in new generation mobile phones Unlike smart phones, which usually use the text-on-nine-keys format, handheld computers have full text keypad or a touch screen keypad. Touch screens or keypad generally used to enter data into handheld devices.

25 Handheld Pocket ComputersSome allow the user to write on the screen using a stylus and incorporate special software for handwriting recognition

26 Handheld Pocket Computers differences with LaptopPocket PCs no CD drives and hard disks Use flash memory Allow the insertion of a memory stick (A memory stick is a removable flash memory card.) Clock speeds of pocket computer processors are limited up to 200 MHz due to considerations about battery life

27 iPad

28 Handheld Pocket Computers differences with LaptopUnlike laptops and notebooks, which use regular microcomputer operating systems, pocket computers have specially designed operating systems OS scaled to the requirements of the software, hardware, and peripherals used in handheld computers

29 Windows CE An operating system from MicrosoftSupport multitasking on handheld devices Real-time operating system meant for handheld computers and embedded systems

30 Windows Phone 7

31 Windows Phone 7 Latest OS from MicrosoftReplaces Windows Mobile for smartphones with multimedia features

32 Windows CE Kernel different from the kernel of the desktop versions of Windows Computing devices with low storage and can be run in about 1 MB of memory. But the Windows CE OS memory needs are larger as compared to Palm OS Support a wider range of hardware than Palm OS. Support different CPUs such as NEC MIPS, Intel StrongARM, AMD X86, etc.

33 Features in Windows CE devicesDigital camera card Games Microsoft Windows Media player and other media players

34 Symbian OS Most widely used operating system for smart phonesRuns exclusively on ARM processors Structure much like that of some desktop operating systems

35 Symbian OS Offers pre-emptive multitasking, multithreadingMemory protection Initially designed for handheld devices with limited resources, strongly emphasizes on memory conservation

36 Symbian OS Embodies event-based programming and when applications are not directly concerned with events, the CPU is switched off Such techniques are very useful in conserving battery life

37 Features of a recent version of Symbian OSSupport for WLAN Hindi and Vietnamese language support to serve a larger range of consumers Native support for Wi-Fi Support for FOTA (firmware over-the-air)

38 Features of a recent version of Symbian OSImproved memory management Low boot-time Native support for Push-to-talk

39 Linux for Mobile DevicesLinux can be modified easily to suit different sorts of hardware and software applications Being an open source OS, it enables the user to customize their device to suit their specific needs

40 Linux Considered to be more secure than most other operating systems.Linux support is easily available from the many forums and associations that promote this OS Many international mobile phone manufacturers turning to Linux for their OS requirements

41 Android

42 Android 2.2 Features Linux Apache ServerCDMA/EVDO, 802.1x, Updated technology support for CDMA/EVDO, 802.1x VPNs (Virtual private networks) Function as tethered modem on connecting to USB Function as WiFi hotspot functionality

43 Android 2.2 Features Softkey pad with auto word prediction; Gestures based UIs, Track multi-touch events Virtual keyboard Camera, Camcorder, Gallery interface and interface for users to select multiple photos for deletion, Built in flash support for Camera and , Digital Zoom

44 Android 2.2 Features Animated screen transitions, Voice SearchSearch bookmarks, history, contacts, and the web from the home screen WGA screen resolution HTML 5 support, Just In Time (JIT) implementation improves speed

45 Android 2.2 Features JavaScript engine integrated to browser, fFile upload fields in the Browser Google Maps and, Microsoft Exchange support Bluetooth 2.1,; Contact sharing over Bluetooth

46 Android 2.2 Features Live Wallpapers Application launcherInstalling applications to the expandable memory Voice dialing; Text-to-Speech engine Adobe flash 10.1 support

47 Summary Handheld Pocket ComputersPocket-sized Differ from smart phones and multimedia phones in that that they can be programmed for customized applications Windows Phone 7 and Windows CE WiFI, Bluetooth for synchroniztion

48 Summary Mac OS4 Windows Phone 7 Symbian OS Linux