Ad Hoc Networks : Technologies and Protocols - University of ...

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QoS at other Networking Layers 241 Figure 8.9. CEDAR: Core nodes in a network Link state propagation: QoS routing in CEDAR is achieved by propagating the bandwidth availability information of stable links in the core graph. The basic idea is that the information about stable high-bandwidth links can be made known to nodes far away in the network, while information about dynamic links or low bandwidth links should remain local. Route Computation: Route computation first establishes a core path from the dominator of the source to that of the destination. The core path provides the directionality of the route from the source to the destination. Using this directional information, CEDAR computes a route adjacent to the core path that satisfies the QoS requirements. 8.5.2 Ticket based routing Ticket based routing [6] is based on the idea of limiting the broadcast messages and directing them toward the right direction. The goal of this approach is to select routes from the ones that are probed for route computation. The source has a certain number of tickets. Tickets are of two kinds: yellow and green. Each probe carries a certain number of tickets. The purpose of the yellow tickets is to maximize the probability of finding a feasible path. Hence probes carrying yellow tickets prefer paths with smaller delays. The purpose of the green tickets is to maximize the probability of finding a low-cost path, where each link is associated with a certain cost. Green tickets prefer paths with smaller costs, which may however have larger delay and hence have less chance to satisfy the delay requirement. The source initiates the probing with a certain number of tickets of each color. At each intermediate node a decision is made as to how many tickets would be forwarded on each of the new probes. This decision is based on the observed QoS metrics of the link. For example, a link with lower delay gets higher number of yellow tickets compared to another link with higher delay. The “Enhanced Ticket Based Routing Algorithm” approach [20] eliminates redundant probing and further optimizes ticket probing.
242 QoS Issues in Ad-hoc Networks 8.6 QoS at other Networking Layers The need for QoS arises at the application layer. The application layer requests the transport layer to provide QoS services. The transport layer must request the routing layer to compute routes satisfying the QoS requirements. This request may need to travel down to the physical layer. Each layer receiving a QoS request from the above layer needs to take the following actions: Check if it can be supported: Each layer needs to see if the QoS requirements are within the limits of what it can support. It needs to notify the higher layer, if it can not support the QoS request. Request the lower layer for supporting it: The current layer processing the QoS request may be able to support it with the help of the lower layers. It needs to map the QoS requirement to the QoS services provided by the lower layer and then send the request to the lower layer. For example, for supporting a QoS route with a certain minimum bandwidth, the routing layer may inform the MAC layer to increase the priority of channel access. Negotiate with the lower/upper layer: When a QoS request is received from the upper layer, it should be checked if the network can support that request. If the QoS demands can not be met, a different QoS requirement may be negotiated by suggesting alternate values of the relevant QoS metrics. Report the application layer on failure to support QoS: After establishing a QoS connection, in case the network fails to support the QoS metrics, the application layer needs to be notified so that it can take appropriate actions. For example, if the network can not find routes requiring a certain minimum bandwidth for supporting real time communication, the application layer can change the encoding or resolution of the multimedia data. The networking layer noticing a change in observed QoS must report it up the layers to the application layer. 8.7 Inter-Layer Design Approaches The previous sections discussed mechanisms at individual networking layers for providing QoS support in ad-hoc networks. The QoS support provided by a layer is dependent on the support from the lower layers as well. INSIGNIA [10] and Cross-Layer Design [5] are two efforts directed toward design and implementation of inter-layer QoS solutions. The rest of the section describes these two frameworks in detail.
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AD HOC NETWORKS Technologies and Pr
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AD HOC NETWORKS Technologies and Pr
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Contents List of Figures List of Ta
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Contents vii 4.7. Conclusions and F
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Contents ix 9.2. Potential Attacks
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List of Figures 1.1 Internet in the
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List of Figures xiii 6.3 COMPOW com
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List of Figures xv 9.1 9.2 An IDS a
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List of Tables 2.1 2.2 2.3 2.4 2.5
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Contributing Authors Samir R. Das i
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Preface Wireless mobile networks an
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Acknowledgments xxiii We wish to ex
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Chapter 1 AD HOC NETWORKS Emerging
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Introduction and Definitions 3 coul
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Introduction and Definitions 5 Secu
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Ad Hoc Network Applications 7 tunis
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Ad Hoc Network Applications 9 The d
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Ad Hoc Network Applications 11 Figu
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Design Challenges 13 example of cro
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Evaluating Ad Hoc Network Protocols
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Overview of the Chapters in this Bo
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Overview of the Chapters in this Bo
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Conclusions 21 1.6 Conclusions This
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Chapter 2 COLLISION AVOIDANCE PROTO
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Performance of collision avoidance
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Framework and Mechanisms for Fair A
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Conclusion 59 In the first part of
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Conclusion 61 [13] [14] [15] [16] [
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Chapter 3 ROUTING IN MOBILE AD HOC
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Flooding 65 vector and link state p
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Flooding 67 centralized approximati
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Proactive Routing 69 status of each
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Proactive Routing 71 Topology Broad
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On-demand Routing 73 reply packets
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On-demand Routing 75 during the lin
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Proactive Versus On-demand Debate 7
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Proactive Versus On-demand Debate 7
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Location-based Routing 81 to find a
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Location-based Routing 83 Figure 3.
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Concluding Remarks 85 relative meri
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Concluding Remarks 87 [14] [15] [16
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Concluding Remarks 89 [42] [43] [44
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Chapter 4 MULTICASTING IN AD HOC NE
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Introduction 93 The mobility of the
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Classifications of Protocols 95 red
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Multicasting Protocols 97 this sect
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Multicasting Protocols 99 as close
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Multicasting Protocols 101 In ODMRP
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Multicasting Protocols 103 hoc netw
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Multicasting Protocols 105 A member
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Multicasting Protocols 107 Figure 4
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Broadcasting 109 “talk” to a ra
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Broadcasting 111 broadcasted packet
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Protocol Comparisons 113 are cluste
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Overarching Issues 115 is user data
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Overarching Issues 117 and RTS/CTS
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Conclusions and Future Directions 1
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Conclusions and Future Directions 1
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Chapter 5 TRANSPORT LAYER PROTOCOLS
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TCP and Ad-hoc Networks 125 Modifie
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TCP and Ad-hoc Networks 127 mechani
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TCP and Ad-hoc Networks 129 timeout
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TCP and Ad-hoc Networks 131 to freq
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TCP and Ad-hoc Networks 133 Figure
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Transport Layer for Ad-hoc Networks
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Modified TCP 137 MAC layers without
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Modified TCP 139 Figure 5.6. TCP-EL
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TCP-aware Cross-layered Solutions 1
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Ad-hoc Transport Protocol 147 in it
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Ad-hoc Transport Protocol Figure 5.
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Summary 151 References [1] [2] [3]
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Chapter 6 ENERGY CONSERVATION Robin
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Energy Consumption in Ad Hoc Networ
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Energy Consumption in Ad Hoc Networ
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Communication-Time Energy Conservat
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Idle-time Energy Conservation 175 a
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Idle-time Energy Conservation 177 T
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Idle-time Energy Conservation 179 k
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Idle-time Energy Conservation 181 F
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Idle-time Energy Conservation 185 t
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Idle-time Energy Conservation 187 c
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Page 216 and 217: Conclusion 191 [6] [7] [8] [9] [10]
Page 218 and 219: Conclusion 193 [33] [34] [35] [36]
Page 222 and 223: Chapter 7 USE OF SMART ANTENNAS IN
Page 224 and 225: Smart Antenna Basics and Models 199
Page 226 and 227: Medium Access Control with Directio
Page 242 and 243: Routing with Directional Antennas 2
Page 248 and 249: Broadcast with Directional Antennas
Page 250 and 251: Broadcast with Directional Antennas
Page 252 and 253: Summary 227 [4] [5] [6] [7] [8] [9]
Page 254 and 255: Chapter 8 QOS ISSUES IN AD-HOC NETW
Page 256 and 257: Introduction 231 The concept of ad-
Page 258 and 259: Physical Layer 233 The 802.11a stan
Page 260 and 261: Medium Access Layer 235 neighbors,
Page 262 and 263: Medium Access Layer 237 Figure 8.5.
Page 264 and 265: QoS Routing 239 where is the number
Page 268 and 269: Inter-Layer Design Approaches 243 8
Page 270 and 271: Conclusion 245 are specifically des
Page 272 and 273: Conclusion 247 [13] S. Mangold, S.
Page 274 and 275: Chapter 9 SECURITY IN MOBILE AD-HOC
Page 276 and 277: Potential Attacks 251 attacks, such
Page 278 and 279: Attack Prevention Techniques 253 9.
Page 280 and 281: Intrusion Detection Techniques 255
Page 290 and 291: Conclusion 265 an important and sti
Page 294 and 295: Index Ad hoc network multicast rout
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