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Energy Consumption in Ad Hoc Networks 155 6.1 Energy Consumption in Ad Hoc Networks In general there are three components to energy consumption in ad hoc networks. First, energy is consumed during the transmission of individual packets. Second, energy is consumed while forwarding those packets through the network. And finally, energy is consumed by nodes that are idle and not transmitting or forwarding packets. To understand how and when energy is consumed in ad hoc networks, it is necessary to consider these costs for data packets forwarded through the network and for control packets used to maintain the network. To lay the groundwork for discussing energy efficient communication protocols in ad hoc networks, we define these costs for communication and introduce energy-saving mechanisms used by many protocols. 6.1.1 Point-to-Point Communication The basis for all communication in ad hoc networks is the point-to-point communication between two nodes. At each node, communication impacts energy consumption in two ways. First, the wireless communication device consumes some base energy when it is activated and idle (see Table 6.2. Note that specifications for most current wireless devices do not provide a differentiation between idle and receive costs). Second, the act of transmitting a packet from one node to another consumes energy at both nodes. Transmission energy is determined by the base transmission costs in the wireless card (see Table 6.1) and the transmit power level at the sender (see Table 6.2). Reception energy depends on the base reception costs in the wireless card and the processing costs for reception (see Table 6.1). The amount of time needed for the packet transfer determines the amount of time the card must be active, and so directly determines the energy consumed by the base card costs for both transmission and reception. This time is determined by two factors: the control overhead from packet transmission and the rate at which the packet is transmitted. The per-packet control overhead is determined by the mechanisms of the medium access control (MAC) protocol. Depending on the chosen protocol, some energy may be consumed due to channel access or contention resolution. For example, in IEEE 802.11 [26], the sender transmits an RTS (ready to send) message to inform the receiver of the sender’s intentions. The receiver replies
156 Energy Conservation with a CTS (clear to send) message to inform the sender that the channel is available at the receiver. The energy consumed for contention resolution includes the transmission and reception of the two messages. Additionally, the nodes may spend some time waiting until the RTS can be sent and so consume energy listening to the channel. In this chapter, we focus on the use of RTS/CTS-based protocols. While it has been shown that such protocols may not be optimal for throughput [37], there is no widely accepted alternative for communication in mobile ad hoc networks. Once channel access and contention resolution have determined that a packet may be sent, many wireless network cards provide multiple rates at which the data can be transmitted, which determines the time needed to send the data (See Table 6.3). The specific transmission rate used is determined by a number of factors, including the signal-to-noise ratio (SNR) and the target reliability of the transmission [19] [41] [58] [60]. In general, the signal strength at the receiver, which determines the SNR, varies directly with the sender’s transmit power level and varies inversely with the distance between the sender and the receiver. This relationship can be formulated as: where the path loss exponent varies from 2 to 6 [51], although is most commonly used as 2 or 4. For the receiver to correctly receive the packet, the SNR must be over a certain threshold. As long as the receive SNR is maintained above this threshold, the transmit power level at the sender can be reduced, directly reducing energy consumption at the sender. The adaptation of the sender’s transmit power level is called power control and is the main tool used to conserve energy during active communication. For the remainder of this chapter, we use power level to mean transmit power level. Finally, energy is consumed to compensate for lost packets, generally via some number of retransmissions of the lost packets. While reliability is generally the domain of the transport layer, the MAC layer in most wireless devices
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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
Page 130 and 131: Multicasting Protocols 105 A member
Page 132 and 133: Multicasting Protocols 107 Figure 4
Page 134 and 135: Broadcasting 109 “talk” to a ra
Page 136 and 137: Broadcasting 111 broadcasted packet
Page 138 and 139: Protocol Comparisons 113 are cluste
Page 140 and 141: Overarching Issues 115 is user data
Page 142 and 143: Overarching Issues 117 and RTS/CTS
Page 144 and 145: Conclusions and Future Directions 1
Page 146 and 147: Conclusions and Future Directions 1
Page 148 and 149: Chapter 5 TRANSPORT LAYER PROTOCOLS
Page 150 and 151: TCP and Ad-hoc Networks 125 Modifie
Page 152 and 153: TCP and Ad-hoc Networks 127 mechani
Page 154 and 155: TCP and Ad-hoc Networks 129 timeout
Page 156 and 157: TCP and Ad-hoc Networks 131 to freq
Page 158 and 159: TCP and Ad-hoc Networks 133 Figure
Page 160 and 161: Transport Layer for Ad-hoc Networks
Page 162 and 163: Modified TCP 137 MAC layers without
Page 164 and 165: Modified TCP 139 Figure 5.6. TCP-EL
Page 166 and 167: TCP-aware Cross-layered Solutions 1
Page 172 and 173: Ad-hoc Transport Protocol 147 in it
Page 174 and 175: Ad-hoc Transport Protocol Figure 5.
Page 176 and 177: Summary 151 References [1] [2] [3]
Page 178 and 179: Chapter 6 ENERGY CONSERVATION Robin
Page 182 and 183: Energy Consumption in Ad Hoc Networ
Page 184 and 185: Communication-Time Energy Conservat
Page 200 and 201: Idle-time Energy Conservation 175 a
Page 202 and 203: Idle-time Energy Conservation 177 T
Page 204 and 205: Idle-time Energy Conservation 179 k
Page 206 and 207: Idle-time Energy Conservation 181 F
Page 210 and 211: Idle-time Energy Conservation 185 t
Page 212 and 213: Idle-time Energy Conservation 187 c
Page 216 and 217: Conclusion 191 [6] [7] [8] [9] [10]
Page 218 and 219: Conclusion 193 [33] [34] [35] [36]
Page 220 and 221: Conclusion 195 [59] [60] [61] [62]
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
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Medium Access Control with Directio
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Routing with Directional Antennas 2
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Broadcast with Directional Antennas
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Broadcast with Directional Antennas
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Summary 227 [4] [5] [6] [7] [8] [9]
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Chapter 8 QOS ISSUES IN AD-HOC NETW
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Introduction 231 The concept of ad-
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Physical Layer 233 The 802.11a stan
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Medium Access Layer 235 neighbors,
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Medium Access Layer 237 Figure 8.5.
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QoS Routing 239 where is the number
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QoS at other Networking Layers 241
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Inter-Layer Design Approaches 243 8
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Conclusion 245 are specifically des
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Conclusion 247 [13] S. Mangold, S.
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Chapter 9 SECURITY IN MOBILE AD-HOC
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Potential Attacks 251 attacks, such
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Attack Prevention Techniques 253 9.
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Intrusion Detection Techniques 255
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Conclusion 265 an important and sti
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Conclusion 267 [24] [25] [26] [27]
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Index Ad hoc network multicast rout
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