ADHOC NETWORKS. By M.K.HAK

Transcription

1 30/08/10 ADHOC NETWORKS By M.K.HAK 1

2 INTRODUCTION Adhoc networks are formed by devices that are able to communicate with each other using a wireless physical medium without having to resort to pre-existing network infrastructure. These are also known as MANETS ie Mobile Adhoc Networks. Fundamental characteristics of ADHOC networks They are able to configure themselves on the fly without the intervention of a centralized administration. The terminals in ADHOC networks can function not only as end systems (executing applications, sending information) as source nodes and receiving the data as destination nodes. They also act as intermediate system i.e. forwarding the packets from the other nodes. ADHOC networks are also called multi -hop wireless networks.

3 It is therefore possible that two nodes will communicate even when they are outside of each others transmission Ranges,Because the intermediate nodes will function as Routers. That is why Wireless networks are called Multihop AD-HAC networks Compared to cellular networks ADHOC networks are more capable to changing demands and physical conditions. Attenuation characteristics of wireless networks are non linear. Energy efficiency will be potentially superior and the increased spatial reuse will yield superior capacity with increased spectral efficiency. These characteristics make ADHOC networks attractive and is tightly linked to heterogeneous network and 4G architecture.

4 Challenges in adhoc networks The need for self configurability and flexibility at various levels i.e. (Dynamic Routing or distributed MAC arrangements). Gross layer optimization can significantly improve the system performance. Classification of AD-HOC Networks Depending on their communication range the wireless AD-HOC networks can be classified into BAN ( Body area Networks these networks having a range of 2 meters.) PAN ( Personal Area Networks having the range of 10 Meters) & WLAN ( Wireless Local Area networks having the range of hundreds of meters) For WLAN the main option is the family of standards i.e. IEEE The main existing technology for implementing BANs and PANs is Bluetooth.

5 The Fundamental characteristics of ADHOC networks The fundamental characteristics of ADHOC Networks are that they are able to configure themselves on the fly without the centralized intervention. The terminals in AD-HOC networks can function not only as end systems ( Executing the applications, sending information as source NODES & receiving the Data as destination nodes) It is there fore possible that two nodes can communicate even when they are outside each others transmission range because the intermediate nodes will function as Routers. That is why ADHOC networks are called Multi band ADHOC Networks. These networks when compared with cellular networks are more capable to changing traffic demands & physical conditions. The attenuation characteristics of the wireless media are non linear, energy efficiency will be potentially superior

6 & the increased spatial re-use will yield superior capacity& thus increase the spectral efficiency. These characteristics make the ADHOC networks.attractive for pervasive communications, a concept that is tightly linked to heterogeneous networks & 4G architecture. The need for self configurability & flexibility Configurability & flexibility at various levels ( for example dynamic routing or distributed medium access control ) poses many new challenges in wireless ADHOC networks, cross layer optimization can significantly improve system performance. Depending upon their communication range the Wireless ADHOC Networks can be classified into BAN,( Body area networks) PAN ( Personal area network) & WLAN ( Wireless local area network) The main existing technology for implementing BAN & PAN networks is blue tooth & for WLAN the standard is I.E.E.E

7 Routing is the most active research field in the adhoc networks as it is related with different communication layers Minimizing the hops is no longer the objective of the routing algorithm but optimization of multiple parameters such as packets error rate over the route, energy consumption, network survivability, routing overheads, possibility of establishing a parallel route etc. We compare the different types of proposed routing algorithms & as an example we illustrate the functioning of non location based on demand uni-cast routing protocol in AD-HOC networks i.e DSR. WE make use of different types of Protocols in AD-HOC networks, for example two disjoint routes may have mutual influence if the node of one route is within the transmission range of the node in the other route which has an impact on the construction of parallel routes

8 Use of TCP over wireless links poses many problems & also it results in additional problems for wireless links. Communication over wireless multi-hop networks inherits these problems but also introduces some additional issues, the nodes mobility introduces unfairness between TCP flows Route failure leads to un-necessary congestion control & MAC contention reduces throughput in the long route Power awareness : since most of the w/l terminals can be expected to have limited energy storage, power awareness is very important. This subject spans over several communication layers so attention is given to different power saving approaches. The objectives are not only the reduction of transmission power but also the management of sleep states or extention of network survivability through the routing which is energy aware..

9 1 However if the medium remains idle for this period the station will go to the back off state. When entering the back off state MS selects back off interval (BI) between zero and the contention window period (CW). CW is the integer no of basic tine slots, if the medium remains idle for the duration of BI time (i.e the value of chosen BI minus the elapsed time since entering the back off state).

10 Carrier sensed multiple access technique/collision detection. When the mobile gets a frame to transmit, it first senses the channel to determine whether another MS is transmitting. If MS senses the channel to be idle for a period which is equal to the inter space frame, then it starts transmitting the frame. When it senses the channel to be busy it will differ the transmission and the station will keep on sensing the channel. At the point of time when the media becomes idle the station will continue sensing and will wait for the period which is equal to inter frame space to elapse again. If the medium becomes busy during this period, the station will go to the deffering state again.

11 Collision will occur if two or more MS s select the same BW provided the condition stated above, that the frame coexist spatially at one or more of the receiving stations. When the collision occurs the station that have caused the collision senses the medium again for the inter frame space and go again to back off state. Selecting a new BI. Randomly with the value of contention window period doubled The other station which stored their remaining BI times aaso waits for inter frame space and then go to the back off state. Basic principal Mobile devices communicate in Peer to Peer fashion. Self organizing network without the need to fixed network infrastructure.

12 Multi-hop communication. Decentralized mobility-adaptive operation. This is the art of networking without a network. Applications Accident warning Floating car data Multi-hop extensions of Info stations. Application for wireless sensor networks Temperature. Measurement details Detect vibrations Make photos. Environmental monitoring Intrusion detection, detection of bush fires, earth quake warning.

13 30/08/10 ADHOC NETWORKS Medical sector : Monitoring of body functions and Implants. Biological sector : Animal tracking, undersea exploration Industrial sector : Remote sensing in power plants Home automation : Remote monitoring of resources such as Electricity, Water and Gas Aerospace sector : Sensor equipped Robots on a plant 13

14 30/08/10 Key advantages :- No expensive infrastructure must be involved. Making use of unlicensed frequency spectrum. Quick distribution of information around sender. 14

15 30/08/10 KEY CHALLENGES All network entities must be mobile requirement of very dynamic technology. Network functions must have high degree of adaptability (mobility, outage). No central entities operation in completely distributed manner. 15

16 30/08/10 ROUTING FOR ADHOC MOBILE NETWORKS : Well known routings are: Link state routing Distance vector routing The Pro-active approach for routing Always maintain all routes Problems : Topologies changes significant network traffic Even when the route is not used 16

17 30/08/10 UNICAST ROUTING PROTOCOLS : Many protocols have been proposed some have been invented specifically for MANETs other are adopted from previously proposed protocols for wired networks. No single protocol works well in all environments. Some attempts made to develop adaptive protocols. 17

18 30/08/10 ROUTING PROTOCOLS : Proactive Protocols : Determines the route independent of traffic pattern Traditionally link state and distance vector routing protocols are proactive Reactive protocols : Maintain routes only if needed Hybrid protocols : Combines Pro-active and re-active elements 18

19 30/08/10 Position based protocols Use the geographic position of nodes for forwarding decisions Latency of route discovery Proactive protocols may have lower latency since the routes are maintained at all times Reactive protocols may have higher latency because a route from X to Y will be found only when X attempts to send Y Overhead of route discovery /maintenance 19

20 30/08/10 Reactive protocols may have lower overhead since routes are determined only if needed Proactive protocols can (but not necessarily) result in higher overhead due to continuous route updating Which of the protocols achieve a better trade off depends on the traffic and mobility patterns 20

21 30/08/10 FLOODING FOR DATA DELIVERY Sender S broadcast data packet P to all neighbors Each node receiving P forwards P to its neighbors Sequence no's are used which avoid the possibility of forwarding the same packet more than once Packet P reaches the destination D provided that D is reachable from sender S 21

22 30/08/10 S Node D does not forward a packet E B F H A G J M C I K L i.e. S represent a node that has received packet P D represents that connected nodes are within each other transmission range N 22

23 30/08/10 RELIABILITY OF ADHOC NETWORKS Wireless links are prone to errors Either because of interference Or because of collisions (collision detection does not work for half duplex networks) High packet loss rate detrimental to transport layer performance 23

24 30/08/10 THE MECHANISM ARE NEEDED TO INCREASE THE RELIABILITY : Forward error correction (FEC) include the redundancy in the packet Automatic repeat request (ARQ) use acknowledgements and re-transmission ARQ for multi hop AD-HOC networks Implicit assumptions :- Packet loss is caused by interference or collisions Retransmission seems to be appropriate 24

25 WHAT HAPPENS IF PACKET LOSS OCCURS DUE TO A NODE LEAVING THE TRANSMISSION RANGE 30/08/10 i. Multiple re-transmission before a sender gives up ii. Massive increase in network congestion Unlikely No route discover strategies favor shortest (i.e. minimal) path Note:- Broadcast (used for rote discovery) are not protected by ARQ 25

26 30/08/10 PROBLEM WITH RANGES FOR MULTI- HOP ADHOC NETWORKS : 1. Large interference, dramatically reduces the capacity 2. Ranges depend on the transmission rate Low rate less vulnerable to interference 1. Broadcast use a lower rate than Uni casts in IEEE ( to make the transmission more reliable) 1. Broadcasts are used for route discovery 2. Uni casts used for data delivery 26

27 30/08/10 CONSEQUENCES :- Routes found via broadcast may not be usable for data traffic It is called Grey zone IEEE is used and will be used for multi hop ADHOC networks Inter-vehicle communication Also as access networks It is certainly not optimal : focus is on single hop networks There are many pit falls when blindly using existing MAC mechanism There is also the need & integrated routing /MAC approach Building a new MAC is hard and expensive 27

28 30/08/10 SECURITY IN MOBILE ADHOC NETWORKS 1. Security needs and threats Security features and need Privacy /Anonymity features and need Dependability features and need Subject /object authentication Data integrity Accountability Confidentiality sort off Availability No unauthorized dissemation of personal data Location, Address,service privacy Availability 28

29 NETWORK SECURITY SEEN AS CUSTOMER-PROVIDER RELATIONSHIP 30/08/10 End user perspective : wants secure end to end communication Operator perspective : Has to provide secure n/w organization as basis for offering a secure communication service Attack types and building blocks of counter measures Passive attack Get content Profiling Other types of attacks - Fabricating or stealing of packets - modification of packets -Active attacks 29

30 30/08/10 SECURITY GOALS WITH RESPECT TO ADHOC ROUTING Routing signaling cannot be spoofed Fabricating routing messages can not be integrated in the network Routing messages cannot be altered in transit except according to the normal functionality of the routing protocol Routing loops cannot be formed through malicious action route cannot be re-directed from the shortest path by malicious action Managed open environment Unauthorized nodes should be excluded from route computation and discovery 30

31 30/08/10 Managed hostile environment The network topology must be exposed neither to adversaries nor to authorized nodes by the routing messages The solutions for secure routing ARAN : Authenticated routing for ADHOC networks Assumptions : MOE (Managed Open Environment ) Trusted certificate server to its public key is known to all nodes Each nodes has non certificate signed by T 31

32 30/08/10 Counter measures used are : Cryptography Monitoring Difference in service classes and ADHOC network 1)Key managed infrastructure 2)Intrusion detection 3)Single administration domain 4)Transiently unavailable Only local monitoring Multiple domains, no clear line of defense 32

33 30/08/10 ADHOC SPECIFIC ATTACK TYPES ARE AS FOLLOWS : Equipment/battery : no obvious line of defense,side channel attacks Radio jamming DLC : attacks on MAC, MAC address Routing : no infrastructure support, no clear line of defense Co-ordination : based on principal of mutual assistance, simple attacks and packet drops 33

34 30/08/10 Security procedures: Route Signed discovery packet (RDP) propagates to sought destination Destination sends back signed route reply (REP) At each hop the following action is taken Validation of original signature Validation of last hop signature When last hop is neither source nor destination replace the last hop signature by your own signature 34

35 30/08/10 ARAN (authentication routing for ADHOC networks ) check list : Unauthorized participation, managed by trusted authority Spoofed route signaling everything is signed Fabricated routing messages 35

36 AD-HOC Routing Protocols It is a convention or standard that controls how nodes decide which way to route packets between computing devices in a mobile AD- HOC networks In AD-HOC networks nodes are not familiar with the topology but instead they have to discover it The new nodes can announce their presence & should keep on listening to the announcements made by the neighbors The node learns about neighbors which are nearer to them & how to reach them & may announce how to reach them. AD-HOC protocols can also be used Literally The following is the list of AD-HOC routing Protocols Pro-active (Table driven routing) Reactive ( On demand routing)

37 Flow Oriented Routing Adaptable Routing. ( Situation aware) Hybrid Routing ( Both pro-active & reactive routing) Hierarchal Routing Geographical Routing Power Aware Routing Multicast Routing Geographical Multicast Routing Other Protocol classes External Links Pro-active ( Table driven Routing )This type of protocol maintains fresh list of destinations& their routes by periodically distributing routing tables throughout the network

38 The main disadvantages of such algorithms are 1) Respective amount of Data for Maintenance Slow reaction of re-structure or failure The examples of Pro-active algorithms are AWDS( Ad-hoc wireless distribution service) Layer 2 wireless mesh routing protocol BABEL. A protocol inspired by DSDV. With faster convergence & trans link quality estimation. CGSR( Clustered gateway switch routing protocol) DFR ( direction forward routing) DBF ( Distributed Bellman Ford routing Protocol) DBDF (Highly dynamic distribution seeking vector) HSR ( Hierarchical state routing Protocol) IRRP( Intra-zone routing protocol & some others)

39 Ant based routing algorithm for mobile AD-HOC networks Admission control enable on demand routing protocol Flow oriented routing This type of protocol finds a route on demand by following present flows One option is to uni-cast consecutively when forwarding Data while promoting a new link. The main disadvantages of such algorithms are 1)It takes a long time while exploring a new route without the prior knowledge May prefer to the entries of existing traffic to compensate for missing knowledge en-routes ADAPTIVE ( Situation aware routing) This type of protocol combines the advantage of PRO-Active & re

40 Reactive Protocols)( On demand routing) This type of protocol finds a route on demand by flooding the network with the route request packets. The main disadvantage of such algorithms are i) High latency time in route finding Excessive flooding which can lead to Network clogging Examples of reactive algorithms are 1) SENCAST 2) Multi -rate AD-HOC on demand Distance Vector Routing Protocol Reliable Ad-Hoc on demand distance vector routing protocol. MEPA ( Minimum exposed path to the attacks in mobile AD-HOC networks

41 Routing is initially established with some pro-actively prospectively routes & then serves the demand for some additionally activated nodes through reactive flooding The main disadvantages of such algorithms are Advantages depends upon the amount of nodes activated Reaction to traffic demand depends upon the gradient of traffic volume

42 OFDM For UMB OFDM is a form of transmission that uses a large number of closed spaced carriers that are modulated with low Rate data.normally these signals would be expected to interfere with each other but there is no mutual interference because these signals are made orthogonal to each other This is achieved by having the carrier spacing equal to the reciprocal to the Symbol period & there will be no mutual Interference The Data to be transmitted is split across all the carriers If some of the carriers are lost due to multipath effect, the Data can be re-constructed by using error correction techniques

43 Sending the Data in packets involving the low Data rates involving all the carriers means that the effect of reflections & inter-symbol interference can be overcome. It also means that a single frequency networks,where all transmitters can transmit on the same channel can be implemented OFDMA (orthogonal frequency Division Multiple Access) uses OFDMA as the basis of modulation schemes but it has been modified for cellular communication For cellular communication we have the advantage of multi-path effects It will still be able to provide the Access to multiple users

44 ULTRA MOBILE BROAD BAND Ultra Mobile Broad Band is the name for the next evolution for CDMA 2000 cellular telecommunication system which is run under the auspices of 3G PP-2 UMB cellular system promises to provide very much faster Data transfer Speeds & enables the system to compete with other Mobile Broad Band systems including WI-MAX& WI-FI The Aim for UMB includes making significant increases to the user Data Rates when compared with existing CDMA 2000 cellular technologies There will be increase in the System capacity & lowering the cost per bit Data transfer

45 Enhancement to the existing services, possibility of new applications & the ability to use new spectrum applications so that UMB can compete with new applications of 4G standards such as WI-MAX & preventing them from gaining the foothold in the Market The UMB broad band standards are to be expected by now & the new systems Using UMB are expected to be available in the market by the middle of 2010 UMB Salient Features UMB offers many new salient feature & techniques that enable it to compete with new 7 other emerging technologies Data Rates of over 275 Mbps in the downlink & over 75 Mbps in the up-link

46 Uses an OFDM/OFDMA air Interface Uses F.D.D Possesses an IP network architecture Has a scalable bandwidth between 1.25 MHz-20 MHz ( NB OFDM/OFDMA systems are well suited for wide & scalable bandwidth. Supports flat, mixed & diluted network architecture The UMB system is supposed to provide the significant leap in terms of capability when compared to the existing CDMA 2000 based systems. The plan is to make UMB operate alongside CDMA X& CDMA X EV-DO & it will offer seamless handoff to & from these services. In this way a phased roll-out of services can be offered

47 UMB air Interface A number of new technologies are being used within the air interface of UMB One of the key technology is OFDM. This technology enables the UMB to carry high Data Rates& also enables the network to use wide & variable Bandwidth according to the requirement of the link OFDMA or Orthogonal frequency division multiple Access uses OFDM as basis of the modulation scheme,but has been modified to cellular communication system including UMB to provide the means of multi-path effects while still being able to provide means of Access to multiple users MIMO For UMB UMB system also uses MIMO. As well as SDMA (Space division Multiple Access) These are the advanced antenna techniques to provide even greater capacity coverage & quality in deployments with multiple Antennas. By using the multi-paths present in any real Radio Path They effectively enable the channel capacity to be increased For beyond to be predicted when using a single Antenna

48 UMB higher layers The new UMB standard utilizes sophisticated control mechanism along with MIMO & SDMA to allow the transmission of variable length packets for each application based upon end to end system capabilities & in QOS. IN this way the system can be optimized according to the prevailing conditions & the requirement of each user UMB IP based structure UMB also supports large variety of services that require extremely low latencies, low jitter& increased spectral efficiencies besides passing packet data & IP. UMB results in supporting the large X-section of advanced mobile Broad Band services by delivering low rate, low latency voice traffic at one end of the spectrum& ultra high speed latency insensitive broadband data traffic It offers better performance for many of the new services being conceived

49 In not too distant future of digital technology, people will be sharing voice Data video & multimedia services among the network consumer electronics PCs & mobile devices throughout the home & even remotely. For example the users will be able to stream video content from a PC or consumer electronic devices such as a camcorder DVD player or a personal video recorder to a flat screen HDTV (high-definition television) display without the use of any wires. A leading candidate for enabling this capability is ultra wideband (UWB), a wireless technology designed for short range, personal area network, or (PANs). This year, UWB is making the transition from laboratories to standardization, a key step toward the development of real world products.

50 Recent industry achievements with UWB range from researchers showing proof-of concept demos, to formation of industry working groupsthat will define the UWB physical layer (PHY) and MAC layer and application that will run on top of the radio platform. In the U.S., the Federal Communication Commission (FCC) has mandated that UWB radio transmission can legally operate in the range from 3.1GHz to 10.6 GHz, at a transmit power of -41dBm/MHz. Japanese regulators have issued the first UQWB experiment license allowing the operation of a UWB transmitter in Japan. Digital Home Requirements Why is UWB considered by many to be the next big thing in the wireless space? For one thing, it allows for high data throughput with low power consumption for distances of less than 10 meter, which is very applicable to the digital home requirements.

51 An example application of UWB would be bringing a mobile device like a portable media player (PMP) in proximity to a content source like PC, Laptop or external hand disk drive Once an authentication& authorization is established, the device & PC can perform bulk data transfer of Video files onto the PMP for later viewing Within the consumer electronics industry, there is the demand for connecting various devices such as DVDs HDTVs Set Top Boxes PVRs, Stereos, Camcorders digital cameras & other CE devices. Wireless use is the Key Factor for adoption in this Category UWB technology A traditional UWB transmitter sends billions of pulses across a very wide spectrum of frequency which is several GHz in bandwidth. The corresponding receiver then translates the pulses into Data by listening to the familiar pulse sequence sent by the transmitter specifically UWB is the technology that occupies the bandwidth of greater than or equal to 500 MHz or greater than 20% of the central frequency. Modern UWB systems use normally (OFDM) to occupy these very large Bandwidths In addition the use of multiple bands in combination with OFDM modulation can provide significant advantage to traditional UWB system

52 In the Multi-band OFDM approach, the available spectrum of 7.5 GHz is divided into several 528 MHz bands. This allows selective implementation of bands at a certain frequency ranges while leaving the other parts of the spectrum un-used The dynamic ability of the radio to operate in certain areas of the spectrum is important, because it can adapt to regularity constraints imposed by the governments around the World

53 ULTRA WIDE BAND Beyond the corporate walls MOTOROLA enterprises Mesh networks Mesh technologies provide convenient, flexible scalable & cost effective extensions of corporate networks in the areas that are typically too hard to cable UWB is a radio technology that can be used at very low energy levels for short range high bandwidth communication, by using a large portion of the Radio spectrum. It is used for radar imaging. Recently it has been used in sensor Data collection, precision locating & tracking applications UWB communication does not interfere with other traditional operators

54 In this way it is able to offer better performance for many of the new services being conceived ULTRA WIDE BAND Beyond the corporate walls MOTOROLA enterprises Mesh networks Mesh technologies provide convenient, flexible scalable & cost effective extensions of corporate networks in the areas that are typically too hard to cable UWB is a radio technology that can be used at very low energy levels for short range high bandwidth communication, by using a large portion of the Radio spectrum. It is used for radar imaging. Recently it has been used in sensor Data collection, precision locating & tracking applications UWB communication does not interfere with other traditional operators

55 It may not be possible to bear for traditional system design &may effect the stability of working communication systems UWB transmits signals across much wider frequency than conventional systems& are usually very difficult to detect The amount of spectrum occupied by a UWB signal is at least 25%of the center frequency i.e UWB signal centered at 2 GHz would be 1 GHz The most common technique to generate a UWB signal is to transmit pulses It communicates within a short distance with high accuracy efficiency & Speed..

56 Current 3G systems are evolving into 4G. As a pathway to4g 3GPP is currently developing Long Term Evolution (LTP) standards & 3GPP2 is working on ULTRA Mobile Broad Band (UMB) Standard. i.e I.E.E.E Standard WI-MAX It is also gaining attention as a solution to 4G problems In air interface techniques all three systems use OFDMA based multi-carrier modulation& MIMO techniques & also other advanced features to greatly improve the mobile services The techniques which are mostly thought of beyond 3G are OFDMA, SC-CDMA, MIMO, FFR (Fractional Frequency Re-Use & advance coding)..

57 UWB is a license free spectrum sharing technique where the transmitted RF energy is spread over a wide bandwidth so that the interference to the existing user is kept at minimum. Driven largely by UWB technology high speed short range wireless personal area networks (WPANS) are expected to profile rate in the coming Years A Band hopping OFDM transmission method developed by the Wireless media alliance & Standardized by ECMA has gained the significant support for developing high Rate (WPANS) One key application for the technology is cable replacement for universal serial BUS(USB) 2..0 devices In addition I.E.E.E & ECMA have formed task groups aimed at developing new specifications for wireless connectivity in 60 GHz frequency band.

58 60 GHz band offers a large amount of BW ( Up to 7 GHZ) & relaxed transmit power limits & therefore has the potential to meet the demand for multi Gega bit Data Rates Although at such high frequency the smaller Antenna Size makes the technique very attractive, but Antenna sector switching & beam forming may be required. Applications Due to extremely low emission levels currently allowed by regulatory agencies UWB systems tend to be short range systems which can be used for Indoor working Due to the short duration of UWB pulses it is easier to engineer extremely high data rates. Conventional OFDM technology can be used subject to the minimum Bandwidth requirement High data rate UWB can enable wireless monitors, the efficient transfer of Data from digital camcoders,

59 Wireless printing of Digital pictures from a Camera without the need of intervening personal computer UWB is used as a part of location systems & real time location systems. The precision capabilities combined with very low power makes it ideal for certain radio frequency sensitive environments such as hospitals & health care UWB is also used to see through the Walls precision radar imaging technology, precision radio imaging technology, precision locating & tracking i.e using distance measurements between the radios.& precision time of arrival based localization approaches. It exhibits excellent efficiency with a special capacity of approximately10 POWER 13BIT/S/SQUARE METER UWB HAS BEEN A PROPOSED TECHNOLOGY FOR USE IN PERSONAL AREA NETWORKS & APPEARED IN THE ieee ADRAFT PAN STANDARD UWB has been having the Limited Success Due to high cost of implementation & performance

60 The fastest data rate publicly shown over UWB is now an impressive 252Mbps at the rate of 480 Mbps is expected to be shown in the not to distant future. Requirements for the digital home include high speed data transfer for multimedia content shortrange connectivity for transfer to other devices, low power consumption due to limited battery capacity and low complexity and cost due to market pricing pressure and alternate wired connectivity options. Transfer of video from a camcorder to a entertainment P.C is one scenario. The second one is to have the view of photos from users still camera removing all the wires to the printer, scanner, mass storage devices and video cameras located in home offices.

61 Closed related is wireless connectivity for consumer devices. Portable customer appliances, audio- video devices such as D.V camcorders, digital still cameras, portable MP3 players, HDTV displays, Personnel video recorders, entertainments P.Cs and emerging personnel video players are likely candidates for the early UWB. Wider Applications of UWB The concept of UWB radio spans different applications and industries and has been coined as the common UWB radio platform. The UWB along with the convergence layer becomes the transport mechanism some of which are currently wired. Some of the more notable applications that will operate on top of the common UWB platform would be wireless universal serial bus (WUSB) IEEE 1394, the next generation of Bluetooth universal plug and play (UPNP).