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Bandwidth Partitioning in Decentralized Wireless Networks
"... This paper addresses the following question, which is of interest in the design of a multiuser decentralized network. Given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partitioned into in ..."
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Cited by 13 (7 self)
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This paper addresses the following question, which is of interest in the design of a multiuser decentralized network. Given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partitioned into in order to maximize the number of simultaneous links in the network? Dividing the available spectrum results in two competing effects. On the positive side, a larger N allows for more parallel, noninterfering communications to take place in the same area. On the negative side, a larger N increases the SINR requirement for each link because the same information rate must be achieved over less bandwidth, which in turn increases the area consumed by each transmission. Exploring this tradeoff and determining the optimum value of N in terms of the system parameters is the focus of the paper. Using stochastic geometry, the optimal SINR threshold – which directly corresponds to the optimal spectral efficiency – is derived for both the low SNR (powerlimited) and high SNR (interferencelimited) regimes. This leads to the optimum choice of the number of frequency bands N in terms of the path loss exponent, power and noise spectral density, desired rate, and total bandwidth. I.
Multihop Relaying for Broadband Wireless Mesh Networks: From Theory to Practice ∗
"... We summarize capacity results to show merits of multihop relaying in broadband cellular mesh networks. Under the guidance of these results, we provide design perspectives on relay deployment, spectrum allocation and endtoend optimization of certain QoS measures such as throughput, coverage, reliab ..."
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Cited by 12 (1 self)
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We summarize capacity results to show merits of multihop relaying in broadband cellular mesh networks. Under the guidance of these results, we provide design perspectives on relay deployment, spectrum allocation and endtoend optimization of certain QoS measures such as throughput, coverage, reliability and robustness. We conclude with an overview of recent standardization activities and remarks on remaining open problems and design challenges. I.
A DelayReliability Analysis for Multihop Underwater Acoustic Communication ABSTRACT
"... This paper investigates the delayreliability tradeoff for multihop underwater acoustic networks. The propagation medium of underwater acoustic channel exhibits distinct characteristics when contrasted with other common propagation media such as copper, fiber, and radio. In particular there are the ..."
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Cited by 9 (2 self)
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This paper investigates the delayreliability tradeoff for multihop underwater acoustic networks. The propagation medium of underwater acoustic channel exhibits distinct characteristics when contrasted with other common propagation media such as copper, fiber, and radio. In particular there are the extremely slow propagation speed of sound in water, high signal attenuation due to absorption, significant delay spreads and intersymbol interference, and rangedependent transmission bandwidth. These features make the delayreliability tradeoff for underwater acoustic channels fundamentally different from other channels. The approach is based on errorexponents which enable a physicallayer comparison of multihopping versus no hops while considering the overall throughput. The analysis shows that for typical network parameters, increasing the number of hops dramatically improves both the achievable information rate and the achievable reliability function, which quantitatively captures the decay rate of the decoding error probability as the coding block length increases asymptotically. Numerical results are presented to illustrate the analysis.
Distributed energyefficient cooperative routing in wireless networks
 IEEE Trans. on Wireless Communications
, 2008
"... Abstract — Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing powerefficient routing algorithms. Most of the existing cooperationbased routing algorithms are implemented by finding a short ..."
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Cited by 9 (1 self)
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Abstract — Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing powerefficient routing algorithms. Most of the existing cooperationbased routing algorithms are implemented by finding a shortestpath route first. As such, these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer. In this paper, we propose a cooperationbased routing algorithm, namely, Minimum Power Cooperative Routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimumpower route. The MPCR algorithm constructs the minimumpower route as a cascade of the minimumpower singlerelay building blocks from the source to the destination. Hence, any distributed shortestpath algorithm can be utilized to find the optimal route with polynomial complexity, while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of 57.36 % compared to the conventional shortestpath routing algorithms. Furthermore, the MPCR algorithm can achieve power saving of 37.64 % compared to the existing cooperative routing algorithms, in which the selected routes are constructed based on the noncooperative routes. I.
Ad hoc networks: To spread or not to spread
 IEEE Communications Magazine
"... Spread spectrum communication – often called Code Division Multiple Access (CDMA) – has been widely adopted over the years for many types interferencechallenged wireless communication systems including cellular and cordless telephones, wireless LANs and PANs, military applications, and global posi ..."
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Cited by 8 (5 self)
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Spread spectrum communication – often called Code Division Multiple Access (CDMA) – has been widely adopted over the years for many types interferencechallenged wireless communication systems including cellular and cordless telephones, wireless LANs and PANs, military applications, and global positioning systems. In this paper, we explore whether CDMA – in either its frequency hopping (FH) or direct sequence (DS) forms – is an appropriate design approach for wireless ad hoc, or mesh, networks. CDMA’s merits for centralized cellular networks were widely debated in the late 1980s through the 1990s, and greatly increased the understanding of CDMA in particular and interferencelimited cellular networks in general. Such a discussion has not occurred for decentralized (ad hoc) networks, and one goal of this paper is to help provoke this debate by explaining the main advantages and disadvantages of CDMA in the context of ad hoc networks as exposed by recent research. We will argue that CDMA does not inherently improve the spectral efficiency of ad hoc networks; on the contrary, its valued interference averaging effect is not appreciable in ad hoc networks due to the irregular distribution of both the transmitters and receivers. On the positive side, both types (FH and DS) of spread spectrum allow for (i) longer hop distances and (ii) a reversal of the usual relationship that the desired transmitter must be closer to the receiver than interfering transmitters. These two facts allow for significant advantages over narrowband (NB) systems in terms of energy efficiency and endtoend delay. We also examine the considerable effect that a spread spectrum physical layer has on MAC protocols. 1
Distributed SpectrumEfficient Routing Algorithms in Wireless Networks
 IEEE Trans. Wireless Commun., Apr
"... This paper applies spectral efficiency as a performance measure for routing schemes and considers how to obtain a good route in a wireless network. The objective for this study is to combine different perspectives from networking and information theory in the design of routing schemes. The problem o ..."
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Cited by 8 (1 self)
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This paper applies spectral efficiency as a performance measure for routing schemes and considers how to obtain a good route in a wireless network. The objective for this study is to combine different perspectives from networking and information theory in the design of routing schemes. The problem of finding the optimum route with the maximum spectral efficiency is difficult to solve in a distributed fashion. Motivated by an informationtheoretic analysis, this paper proposes two suboptimal alternatives, namely, the approximatelyidealpath routing (AIPR) scheme and the distributed spectrumefficient routing (DSER) scheme. AIPR finds a path to approximate an optimum regular path and requires location information. DSER is more amenable to distributed implementations based on BellmanFord or Dijkstra’s algorithms. The spectral efficiencies of AIPR and DSER for random networks approach that of nearestneighbor routing in the low signaltonoise ratio (SNR) regime and that of singlehop routing in the high SNR regime. In the moderate SNR regime, the spectral efficiency of DSER is up to twice that of nearestneighbor or singlehop routing. I. BACKGROUND AND MOTIVATION As wireless communications are extended beyond the last hop of networks, a better understanding of wireless relaying (including routing as a special case) is needed to deploy efficient multihop wireless networks. Research from different perspectives, e.g., networking and information theory, yields in different relaying paradigms for wireless networks [1]–[7]. The goal of this
Reliability bounds for delayconstrained multihop networks
 in 44th Annual Allerton Conference
, 2006
"... Abstract — We consider a linear multihop network composed of multistate discretetime memoryless channels over each hop, with orthogonal timesharing across hops under a halfduplex relaying protocol. We analyze the probability of error and associated reliability function [1] over the multihop ne ..."
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Cited by 5 (1 self)
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Abstract — We consider a linear multihop network composed of multistate discretetime memoryless channels over each hop, with orthogonal timesharing across hops under a halfduplex relaying protocol. We analyze the probability of error and associated reliability function [1] over the multihop network; with emphasis on random coding and sphere packing bounds, under the assumption of pointtopoint coding over each hop. In particular, we define the system reliability function for the multihop network and derive lower and upper bounds on this function to specify the reliabilityoptimal operating conditions of the network under an endtoend constraint on the total number of channel uses. Moreover, we apply the reliability analysis to bound the expected endtoend latency of multihop communication under the support of an automatic repeat request (ARQ) protocol. Considering an additive white
Analysis of a simple multihop underwater acoustic network
 in Proc. ACM WuWNeT 2008
"... A multihop underwater acoustic network, which consists of a series of equaldistance hops connected by relay transceivers in a tandem, is considered. Messages are originated as coded packets from a source node at one end, relayed (decoded and reencoded) sequentially hop by hop, and finally received ..."
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Cited by 4 (3 self)
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A multihop underwater acoustic network, which consists of a series of equaldistance hops connected by relay transceivers in a tandem, is considered. Messages are originated as coded packets from a source node at one end, relayed (decoded and reencoded) sequentially hop by hop, and finally received by a destination node at the other end of the network. Several key characteristics of underwater acoustic channels, namely, frequencydependent signal attenuation and noise, interhop interference, halfduplex constraint, and large propagation delay, are taken into account in the analysis. A simple transmission protocol with spatial reuse is considered, and the transmission schedule is designed to satisfy the halfduplex constraint on relay transceivers in the presence of large propagation delay. To efficiently cope with frequencydependent channel characteristic and interhop interference, the power spectral density function of signaling is analytically optimized in a way analogous to waterfilling. Furthermore, the problem of determining the minimum number of hops to support a prespecified rate and reliability with and without a maximum coded packet length constraint is examined. Finally, numerical results are presented to illustrate the analysis.
BandwidthSINR tradeoffs in spatial networks
 in Proc. IEEE International Symposium on Information Theory
, 2007
"... Abstract — This paper addresses the following question, which is of interest in the design of a multiuser decentralized network: given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partition ..."
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Cited by 4 (0 self)
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Abstract — This paper addresses the following question, which is of interest in the design of a multiuser decentralized network: given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partitioned into to maximize the number of simultaneous transmissions in the network? Dividing the available spectrum reduces the number of users on each band and therefore decreases multiuser interference level, but also increases the SINR requirement for each transmission because the same information rate must be achieved over a smaller bandwidth. Exploring this tradeoff between bandwidth and SINR and determining the optimum value of N in terms of the system parameters is the focus of the paper. Using stochastic geometry, we analytically derive the optimal SINR threshold on this tradeoff curve and show that it is a function of only the path loss exponent. Furthermore, the optimal SINR point lies between the lowSINR (powerlimited) and highSINR (bandwidthlimited) regimes. I.