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Out-of-Order Packet Delivery Out-of-order (OOO) delivery may occur due to: Route changes Link layer retransmissions schemes that deliver OOO Significantly OOO delivery confuses TCP, triggering fast retransmit Potential solutions: Deterministically prefer one route over others, even if multiple routes are known Reduce OOO delivery by re-ordering received packets • can result in unnecessary delay in presence of packet loss Turn off fast retransmit • can result in poor performance in presence of congestion 392
Impact of Acknowledgements TCP Acks (and link layer acks) share the wireless bandwidth with TCP data packets Data and Acks travel in opposite directions In addition to bandwidth usage, acks require additional receive-send turnarounds, which also incur time penalty To reduce frequency of send-receive turnaround and contention between acks and data 393
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Mobile Ad Hoc Networks: Routing, MA
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Introduction Unicast routing Mult
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Coverage Not intended to be exhaus
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Mobile Ad Hoc Networks Formed by w
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Mobile Ad Hoc Networks (MANET) Mob
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Many Applications Personal area ne
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Many Variations Traffic characteri
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Challenges Limited wireless transm
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Research on Mobile Ad Hoc Networks
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Assumption Unless stated otherwise
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Why is Routing in MANET different ?
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Proactive protocols Routing Protoco
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Overview of Unicast Routing Protoco
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A Flooding for Data Delivery B H S
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A Flooding for Data Delivery B H
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Flooding for Data Delivery: Advanta
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Flooding of Control Packets Many p
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A B Route Discovery in DSR H S E C
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Route Discovery in DSR Destination
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Route Reply in DSR Route Reply can
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A B Data Delivery in DSR H DATA [S,
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DSR Optimization: Route Caching Ea
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A B Use of Route Caching [S,E,F,J,D
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Use of Route Caching: Can Reduce Pr
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Route Caching: Beware! Stale cache
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Dynamic Source Routing: Disadvantag
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Flooding of Control Packets How to
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X = last known location of node D,
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LAR Only nodes within the request
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LAR Variations: Adaptive Request Zo
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Location-Aided Routing The basic p
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Detour Routing Using Location Infor
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Distance Routing Effect Algorithm f
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Relative Distance Micro-Discovery R
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Geographic Distance Routing (GEDIR)
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Grid Location Service (GLS) [Li00Mo
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Query Localization [Castaneda99Mobi
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G F E B A S C D Query Localization:
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Broadcast Storm Problem [Ni99Mobico
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Solutions for Broadcast Storm Prob
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Solutions for Broadcast Storms Dis
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Ad Hoc On-Demand Distance Vector Ro
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A B Route Requests in AODV H S E C
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A B Route Requests in AODV H S E C
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A Reverse Path Setup in AODV B H S
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A B Route Reply in AODV H S E C I G
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A Forward Path Setup in AODV B H S
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Timeouts A routing table entry mai
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Route Error When node X is unable
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Link Failure Detection Hello messa
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Why Sequence Numbers in AODV A B C
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Summary: AODV Routes need not be i
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Link Reversal Algorithm [Gafni81] A
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Link Reversal Algorithm A B F C E G
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Link Reversal Algorithm Attempts t
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Partial Reversal Method A B F C E G
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Link Reversal Methods: Advantages
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Link Reversal in a Partitioned Netw
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Full Reversal in a Partitioned Netw
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Full Reversal in a Partitioned Netw
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Temporally-Ordered Routing Algorith
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E D Partition Detection in TORA A N
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E D Partition Detection in TORA A N
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E D Partition Detection in TORA A F
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E D Partition Detection in TORA A F
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TORA Design Decision TORA performs
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So far ... All nodes had identical
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Core-Extraction Distributed Ad Hoc
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Link State Propagation in CEDAR Th
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H G B CEDAR: Core Maintenance A C E
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H G B CEDAR Route Discovery A C E S
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Advantages CEDAR Route discovery/ma
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Proactive Protocols Most of the sc
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Optimized Link State Routing (OLSR)
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Optimized Link State Routing (OLSR)
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OLSR OLSR floods information throu
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Destination-Sequenced Distance-Vect
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Hybrid Protocols 171
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ZRP All nodes within hop distance
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B F ZRP: Example with Zone Radius =
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B F ZRP: Example with d = 2 A S C D
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LANMAR Routing to Nodes Within Scop
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LANMAR Routing to Nodes Outside Sco
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Geodesic Routing Without Anchors [B
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Routing Protocols discussed so far
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Other Routing Protocols Plenty of
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Power-Aware Routing [Singh98Mobicom
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Power-Aware Routing Possible modifi
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Associativity-Based Routing (ABR) [
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Preemptive Routing [Goff01MobiCom]
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Quality-of-Service Several proposa
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Multicasting in Mobile Ad Hoc Netwo
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Multicasting in MANET Need to take
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AODV Group Sequence Number In our
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Joining the Multicast Tree: AODV H
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Joining the Multicast Tree: AODV H
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Sending Data on the Multicast Tree
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Since J is not a leaf node, it must
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Leaving a Multicast Tree: AODV H C
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Handling a Link Failure: AODV Multi
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Merging Partitions: AODV If the ne
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Merging Partitions: AODV Assume th
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Q Merging Partitions: AODV B RREQ (
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Group Hello (update) Q Merging Part
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On-Demand Multicast Routing Protoco
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ODMRP No explicit join or leave pr
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Geocasting in Mobile Ad Hoc Network
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Geocasting [Navas97Mobicom] Navas
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Simple Flooding-Based Geocasting U
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Geocasting based on Location-Aided
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Geocast LAR If all routes between
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Anycasting with Modified TORA [Ko20
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DAG for Anycasting Since links bet
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Geocasting using Modified Anycastin
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Other Geocasting Schemes [Macwan01
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Some Related Work Content-based Mu
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Capacity of Fixed Ad Hoc Networks [
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Continues from last slide … Dela
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Measured Scaling Law [Gupta01] Mea
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Medium Access Control Protocols 263
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Hidden Terminal Problem Node B can
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Reliability Wireless links are pro
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IEEE 802.11 Wireless MAC Distribut
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Collision Avoidance With half-dupl
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B1 = 25 B2 = 20 cw = 31 DCF Example
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MAC Protocols: Issues Hidden Termi
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Binary Exponential Backoff in DCF
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IEEE 802.11 Distributed Coordinatio
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Fairness Issue Assume that initial
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MACAW Solution for Fairness When a
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Distributed Fair Scheduling (DFS) [
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Impact of Collisions After collisi
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Distributed Fair Scheduling DFS us
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Fairness in Multi-Hop Networks Not
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Balanced MAC degree of node j p_ij
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Balanced MAC Results show that it
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Estimation-Based Fair MAC Fair sha
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Proportional Fair Contention Resolu
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Sender-Initiated Protocols The pro
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Using Receiver’s Help in a Sender
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Receiver-Based Adaptive Rate Contro
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Capacity and MAC Protocols The MAC
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Energy Conserving MAC Since many m
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A Power Aware Multi-Access Protocol
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PAMAS PAMAS uses a control channel
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Another Proposal in PAMAS To avoid
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UDP on Mobile Ad Hoc Networks 317
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UDP Performance Several relevant s
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UDP Performance Difficult to ident
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Overview of Transmission Control Pr
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Transmission Control Protocol (TCP)
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Cumulative Acknowledgements A new
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Window Based Flow Control Sliding
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Window Based Flow Control Congesti
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How does TCP detect a packet loss?
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Retransmission Timeout (RTO) calcul
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Fast Retransmission Timeouts can t
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Congestion Avoidance and Control S
Page 341 and 342: Congestion Control On detecting a
Page 343 and 344: Congestion window (segments) 25 20
Page 345 and 346: ssthresh = Fast Recovery min(cwnd,
Page 347 and 348: Slow-start Congestion avoidance F
Page 349 and 350: Performance of TCP Several factors
Page 351 and 352: Random Errors May Cause Fast Retran
Page 357 and 358: Sometimes Congestion Response May b
Page 359 and 360: Burst Errors May Cause Timeouts If
Page 361 and 362: Impact of Transmission Errors TCP
Page 363 and 364: This Tutorial This tutorial consid
Page 365 and 366: Mobile Ad Hoc Networks Mobility ca
Page 367 and 368: Impact of Multi-Hop Wireless Paths
Page 369 and 370: Ideal Throughput f(i) = fraction o
Page 371 and 372: Impact of Mobility 20 m/s 30 m/s Id
Page 373 and 374: Actual throughput But not always
Page 375 and 376: mobility causes link breakage, resu
Page 377 and 378: B C A Why Does Throughput Improve?
Page 379 and 380: Network feedback How to Improve Thr
Page 381 and 382: Actual throughput Performance Impro
Page 383 and 384: Issues Network Feedback Network kn
Page 385 and 386: To Cache or Not to Cache Average sp
Page 387 and 388: Issues To Cache or Not to Cache Ca
Page 389 and 390: TCP Performance Two factors result
Page 391: Issues RTO After Route Repair Same
Page 395 and 396: Security Issues 395
Page 397 and 398: Security Issues in Mobile Ad Hoc Ne
Page 399 and 400: Resurrecting Duckling [Stajano99]
Page 401 and 402: Secure Routing Establishing a Cert
Page 403 and 404: Techniques for Intrusion-Resistant
Page 405 and 406: Intrusion Detection [Zhang00Mobicom
Page 407 and 408: Packet Purse Model [Byttayn00MobiHo
Page 409 and 410: Existing Implementations Several i
Page 411 and 412: CMU Implementation: Lessons Learned
Page 413 and 414: BBN Implementation [Ramanathan00Wcn
Page 415 and 416: Link layer Implementation Issues: W
Page 417 and 418: Implementation Issues: Address Assi
Page 419 and 420: Implementation Issues: Security Ho
Page 421 and 422: Implementation Issues Only some is
Page 423 and 424: Distributed Algorithms for Mobile A
Page 425 and 426: Distributed Algorithms There is al
Page 427 and 428: Related Standards Activities 427
Page 429 and 430: Internet Engineering Task Force (IE
Page 431 and 432: Bluetooth [Haartsen98,Bhagawat00Tut
Page 433 and 434: Bluetooth: Piconet A channel is ch
Page 435 and 436: Bluetooth: Scatternet Several pico
Page 437 and 438: Open Issues in Mobile Ad Hoc Networ
Page 439 and 440: Related Research Areas Algorithms
Page 441: Thank you !! For more information,
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