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32
Delay analysis for cognitive radio networks with random access: A fluid queue view
- In Proc. IEEE INFOCOM
, 2010
"... Abstract—We consider a cognitive radio network where multiple secondary users (SUs) contend for spectrum usage, using random access, over available primary user (PU) channels. Our focus is on SUs ’ queueing delay performance, for which a systematic understanding is lacking. We take a fluid queue app ..."
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Abstract—We consider a cognitive radio network where multiple secondary users (SUs) contend for spectrum usage, using random access, over available primary user (PU) channels. Our focus is on SUs ’ queueing delay performance, for which a systematic understanding is lacking. We take a fluid queue approximation approach to study the steady-state delay performance of SUs, for cases with a single PU channel and multiple PU channels. Using stochastic fluid models, we represent the queue dynamics as Poisson driven stochastic differential equations, and characterize the moments of the SUs ’ queue lengths accordingly. Since in practical systems, a secondary user would have no knowledge of other users ’ activities, its contention probability has to be set based on local information. With this observation, we develop adaptive algorithms to find the optimal contention probability that minimizes the mean queue lengths. Moreover, we study the impact of multiple channels and multiple interfaces, on SUs’ delay performance. As expected, the use of multiple channels and/or multiple interfaces leads to significant delay reduction. I.
Cross-layer analysis of the end-to-end delay distribution in wireless sensor networks
- in Proc. IEEE RTSS
, 2009
"... Abstract—Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic analysis of QoS is essential. One important metric ..."
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Abstract—Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic analysis of QoS is essential. One important metric of QoS in WSNs is the probability distribution of the end-to-end delay. Compared to other widely used delay performance metrics such as the mean delay, delay variance, and worst-case delay, the delay distribution can be used to obtain the probability to meet a specific deadline for QoS-based communication in WSNs. To investigate the end-to-end delay distribution, in this paper, a comprehensive cross-layer analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework is generic and can be parameterized for a wide variety of MAC protocols and routing protocols. Case studies with the CSMA/CA MAC protocol and an anycast protocol are conducted to illustrate how the developed framework can analytically predict the distribution of the end-to-end delay. Extensive test-bed experiments and simulations are performed to validate the accuracy of the framework for both deterministic and random deployments. Moreover, the effects of various network parameters on the distribution of end-to-end delay are investigated through the developed framework. To the best of our knowledge, this is the first work that provides a generic, probabilistic cross-layer analysis of end-to-end delay in WSNs. Index Terms — Delay distribution, quality of service (QoS), realtime systems, wireless sensor networks. I.
Analyzing the Performance of Multi-Hop Underwater Acoustic Sensor Networks
- In Proceedings of the OCEANS 2007–Europe
, 2007
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Delay and Throughput in Random Access Wireless Mesh Networks
"... The wireless mesh networks (WMNs) are emerging as a popular means of providing connectivity to communities in both affluent and poor parts of the world. The presence of backbone mesh routers and the use of multiple channels and interfaces allow mesh networks to have better capacity than infrastructu ..."
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Cited by 9 (0 self)
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The wireless mesh networks (WMNs) are emerging as a popular means of providing connectivity to communities in both affluent and poor parts of the world. The presence of backbone mesh routers and the use of multiple channels and interfaces allow mesh networks to have better capacity than infrastructure-less multihop ad hoc networks. In this paper we characterize the average delay and capacity in random access MAC based WMNs. We model residential area WMNs as open G/G/1 queuing networks. The analytical model takes into account the mesh client and router density, the random packet arrival process, the degree of locality of traffic and the collision avoidance mechanism of random access MAC. The diffusion approximation method is used to obtain closed form expressions for end-to-end packet delay and maximum achievable per-node throughput. The analytical results indicate that how the performance of WMNs scales with the number of mesh routers and clients. We also discuss that how the results obtained for WMNs compare with well known results on asymptotic capacity of infrastructure-less ad hoc networks. The results obtained from simulations agree closely with the analytical results.
Queuing Delay and Achievable Throughput in Random Access Wireless Ad Hoc Networks
, 2006
"... In this paper we focus on characterizing the average end-to-end delay and maximum achievable per-node throughput in random access multihop wireless ad hoc networks with stationary nodes. We present an analytical model that takes into account the number of nodes, the random packet arrival process, th ..."
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Cited by 3 (0 self)
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In this paper we focus on characterizing the average end-to-end delay and maximum achievable per-node throughput in random access multihop wireless ad hoc networks with stationary nodes. We present an analytical model that takes into account the number of nodes, the random packet arrival process, the extent of locality of traffic, and the back off and collision avoidance mechanisms of random access MAC. We model random access multihop wireless networks as open G/G/1 queuing networks and use the diffusion approximation to evaluate closed form expressions for the average end-to-end delay. The mean service time of nodes is derived and used to obtain the maximum achievable per-node throughput. The analytical results obtained here from the queuing network analysis are discussed with regard to similarities and differences from the well established information-theoretic results on throughput and delay scaling laws in ad hoc networks. We also investigate the extent of deviation of delay and achievable throughput in a real world network from the analytical results presented in this paper. We perform extensive simulations and verify that the analytical results closely match the results obtained from simulations.
Delay and Capacity in Energy Efficient Sensor Networks
"... MAC protocols for wireless sensor networks employ periodic switching to low energy sleep state in order to enhance network lifetime. During the sleep state, the sensors do not perform energy consuming operations such as receiving and transmitting packets. During the normal state, CSMA based multi-ac ..."
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MAC protocols for wireless sensor networks employ periodic switching to low energy sleep state in order to enhance network lifetime. During the sleep state, the sensors do not perform energy consuming operations such as receiving and transmitting packets. During the normal state, CSMA based multi-access mechanism is the MAC protocol of choice in distributed, unsynchronized sensor networks. The energy conserving mechanism has a two-fold effect on delay in the network. On one hand it increases delay since many a times the intended receiver may be in sleep state and the transmitter has to delay the transmission to allow the receiver to wake up. On the other hand, since the sensors do not transmit in sleep state, the contention for channel is reduced which tends to improve delay. In this paper we present a queuing theoretic analysis of delay and capacity in sensor networks with uncoordinated sleep mechanism and characterize the energy-delay-capacity tradeoffs. We consider several sleep states which consume different levels of energy. We model sensor networks as queuing networks and evaluate closed form expressions for average packet delay and maximum achievable pernode throughput in terms of network parameters and sleep schedule. Comparisons with the performance of networks that do not employ any energy conserving mechanisms show that any of the energy conserving sleep states in the networks considered in this paper leads to considerable degradation in delay and capacity of the network.
Delay Constrained Throughput Analysis of a Correlated MIMO Wireless Channel
"... Abstract—The maximum traffic arrival rate at the network for a given delay guarantee (delay constrained throughput) has been well studied for wired channels. However, few results are available for wireless channels, especially when multiple antennas are employed at the transmitter and receiver. In t ..."
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Abstract—The maximum traffic arrival rate at the network for a given delay guarantee (delay constrained throughput) has been well studied for wired channels. However, few results are available for wireless channels, especially when multiple antennas are employed at the transmitter and receiver. In this work, we analyze the network delay constrained throughput of a multiple input multiple output (MIMO) wireless channel with time-varying spatial correlation. The MIMO channel is modeled via its virtual representation, where the individual spatial paths between the antenna pairs are Gilbert-Elliot channels. The whole system is then described by a K-State Markov chain, where K depends upon the degree of freedom (DOF) of the channel. We prove that the DOF based modeling is indeed accurate. Furthermore, we study the impact of the delay requirements at the network layer, violation probability and the number of antennas on the throughput under different fading speeds and signal strength. Index Terms—Delay constrained throughput, correlated multiple-input-multiple-output (MIMO), Markov modeling, stochastic network calculus, moment generating function (MGF). I.
A Queuing Network Model Based on Ad Hoc Routing Networks for Multimedia
- Communications, APPLIED MATHEMATICS & INFORMATION SCIENCES
, 2012
"... Abstract: In real-time multimedia applications, the delivery of multimedia information over ad hoc wireless networks has presented difficult challenges requiring considerable research efforts to overcome. To analyze the delivering multimedia packets between mobile nodes with low end-to-end delay an ..."
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Abstract: In real-time multimedia applications, the delivery of multimedia information over ad hoc wireless networks has presented difficult challenges requiring considerable research efforts to overcome. To analyze the delivering multimedia packets between mobile nodes with low end-to-end delay and less bandwidth overhead while ensuring high throughput, we propose a queuing network model based on our adaptive-gossip algorithm with probability p n that conserves network bandwidth at each node by reducing the routing overhead. We also analyze the queuing delay in regard to the number of nodes, the transmission range of a node, the behavior of routing, and MAC protocols. We present both analytical and experimental results to thoroughly evaluate our proposed queuing network model, which demonstrates the advantages of an adaptive-gossiping routing method over flooding routing.
A Network Calculus Approach for the Analysis of Multi-Hop Fading Channels
, 1207
"... A fundamental problem for the delay and backlog analysis across multi-hop paths in wireless networks is how to account for the random properties of the wireless channel. Since the usual statistical models for radio signals in a propagation environment do not lend themselves easily to a description o ..."
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A fundamental problem for the delay and backlog analysis across multi-hop paths in wireless networks is how to account for the random properties of the wireless channel. Since the usual statistical models for radio signals in a propagation environment do not lend themselves easily to a description of the available service rate, the performance analysis of wireless networks has resorted to higher-layer abstractions, e.g., using Markov chain models. In this work, we propose a network calculus that can incorporate common statistical models of fading channels and obtain statistical bounds on delay and backlog across multiple nodes. We conduct the analysis in a transfer domain, which we refer to as the SNR domain, where the service process at a link is characterized by the instantaneous signal-to-noise ratio at the receiver. We discover that, in the transfer domain, the network model is governed by a dioid algebra, which we refer to as (min, ×) algebra. Using this algebra we derive the desired delay and backlog bounds. An application of the analysis is demonstrated for a simple multi-hop network with Rayleigh fading channels. I.
