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Capacity of Fading Channels with Channel Side Information
, 1997
"... We obtain the Shannon capacity of a fading channel with channel side information at the transmitter and receiver, and at the receiver alone. The optimal power adaptation in the former case is "waterpouring" in time, analogous to waterpouring in frequency for timeinvariant frequencyselective fadi ..."
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Cited by 395 (23 self)
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We obtain the Shannon capacity of a fading channel with channel side information at the transmitter and receiver, and at the receiver alone. The optimal power adaptation in the former case is "waterpouring" in time, analogous to waterpouring in frequency for timeinvariant frequencyselective fading channels. Inverting the channel results in a large capacity penalty in severe fading.
Fading Channels: InformationTheoretic And Communications Aspects
 IEEE TRANSACTIONS ON INFORMATION THEORY
, 1998
"... In this paper we review the most peculiar and interesting informationtheoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information ..."
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Cited by 289 (1 self)
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In this paper we review the most peculiar and interesting informationtheoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information theory of fading channels, by emphasizing capacity as the most important performance measure. Both singleuser and multiuser transmission are examined. Further, we describe how the structure of fading channels impacts code design, and finally overview equalization of fading multipath channels.
Capacity Regions for Wireless Ad Hoc Networks
 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
, 2003
"... We define and study capacity regions for wireless ad hoc networks with an arbitrary number of nodes and topology. These regions describe the set of achievable rate combinations between all sourcedestination pairs in the network under various transmission strategies, such as variablerate transmissi ..."
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Cited by 200 (15 self)
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We define and study capacity regions for wireless ad hoc networks with an arbitrary number of nodes and topology. These regions describe the set of achievable rate combinations between all sourcedestination pairs in the network under various transmission strategies, such as variablerate transmission, singlehop or multihop routing, power control, and successive interference cancellation (SIC). Multihop cellular networks and networks with energy constraints are studied as special cases. With slight modifications, the developed formulation can handle node mobility and timevarying flatfading channels. Numerical results indicate that multihop routing, the ability for concurrent transmissions, and SIC significantly increase the capacity of ad hoc and multihop cellular networks. On the other hand, gains from power control are significant only when variablerate transmission is not used. Also, timevarying flatfading and node mobility actually improve the capacity. Finally, multihop routing greatly improves the performance of energyconstraint networks.
Capacity and Optimal Resource Allocation for Fading Broadcast Channels: Part I: Ergodic Capacity
"... ..."
HighPerformance Communication Networks
"... Contents 1 Wireless Networks 1 1.1 Introduction ...................................... 1 1.1.1 History of Wireless Networks ........................ 2 1.1.2 Wireless Data Vision ............................. 5 1.1.3 Technical Challenges ............................. 7 1.2 The Wireless Channel ...... ..."
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Cited by 132 (4 self)
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Contents 1 Wireless Networks 1 1.1 Introduction ...................................... 1 1.1.1 History of Wireless Networks ........................ 2 1.1.2 Wireless Data Vision ............................. 5 1.1.3 Technical Challenges ............................. 7 1.2 The Wireless Channel ................................. 8 1.2.1 Path loss ................................... 9 1.2.2 Shadow Fading ................................ 10 1.2.3 Multipath Flatfading and Intersymbol Interference ............. 11 1.2.4 Doppler Frequency Shift ........................... 12 1.2.5 Interference .................................. 13 1.2.6 Infrared versus Radio ............................ 13 1.2.7 Capacity Limits of Wireless Channels .................... 14 1.3 Link Level Design .................................. 15 1.3.1 Modulation Techniques ............................ 15 1.3.2 Channel Coding and Link Layer Retransmission .............. 16 1.3.3 FlatFading Countermeasures ..
Adaptive Coded Modulation for Fading Channels
 IEEE TRANS. COMMUN
, 1998
"... We apply coset codes to adaptive modulation in fading channels. Adaptive modulation is a powerful technique to improve the energy efficiency and increase the data rate over a fading channel. Coset codes are a natural choice to use with adaptive modulation since the channel coding and modulation desi ..."
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Cited by 129 (10 self)
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We apply coset codes to adaptive modulation in fading channels. Adaptive modulation is a powerful technique to improve the energy efficiency and increase the data rate over a fading channel. Coset codes are a natural choice to use with adaptive modulation since the channel coding and modulation designs are separable. Therefore, trellis and lattice codes designed for additive white Gaussian noise (AWGN) channels can be superimposed on adaptive modulation for fading channels, with the same approximate coding gains. We first describe the methodology for combining coset codes with a general class of adaptive modulation techniques. We then apply this methodology to a spectrally efficient adaptive Mary quadrature amplitude modulation (MQAM) to obtain trelliscoded adaptive MQAM. We present analytical and simulation results for this design which show an effective coding gain of 3 dB relative to uncoded adaptive MQAM for a simple fourstate trellis code, and an effective 3.6dB coding gain for an eightstate trellis code. More complex trellis codes are shown to achieve higher gains. We also compare the performance of trelliscoded adaptive MQAM to that of coded modulation with builtin time diversity and fixedrate modulation. The adaptive method exhibits a power savings of up to 20 dB.
Degrees of freedom in adaptive modulation: a unified view
 IEEE Trans. Commun
, 2001
"... Abstract—We examine adaptive modulation schemes for flatfading channels where the data rate, transmit power, and instantaneous BER are varied to maximize spectral efficiency, subject to an average power and BER constraint. Both continuousrate and discreterate adaptation are considered, as well as ..."
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Cited by 124 (4 self)
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Abstract—We examine adaptive modulation schemes for flatfading channels where the data rate, transmit power, and instantaneous BER are varied to maximize spectral efficiency, subject to an average power and BER constraint. Both continuousrate and discreterate adaptation are considered, as well as average and instantaneous BER constraints. We find the general form of power, BER, and data rate adaptation that maximizes spectral efficiency for a large class of modulation techniques and fading distributions. The optimal adaptation of these parameters is to increase the power and data rate and decrease the BER as the channel quality improves. Surprisingly, little spectral efficiency is lost when the power or rate is constrained to be constant. Hence, the spectral efficiency of adaptive modulation is relatively insensitive to which degrees of freedom are adapted. Index Terms—Adaptive modulation, communication systems, fading channels, spectral efficiency. I.
Increase in capacity of multiuser OFDM system using dynamic subchannel allocation
 in Proc. IEEE Veh. Technol. Conf
"... AbstractThis paper investigates the problem of dynamic multiuser subchannel allocation in the downlink of OFDM systems. The assumptions are that the channel model is quasistatic and that the base station has perfect channel information. In traditional TDMA or FDMA systems, resource allocation for ..."
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Cited by 122 (2 self)
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AbstractThis paper investigates the problem of dynamic multiuser subchannel allocation in the downlink of OFDM systems. The assumptions are that the channel model is quasistatic and that the base station has perfect channel information. In traditional TDMA or FDMA systems, resource allocation for each user is nonadaptively fixed, and the waterfilling power spectrum is known to be optimal. Since the subchannel allocations among the users are not optimized, a group of users is likely to suffer from poor channel gains resulting from large path loss and random fading. To resolve this problem, we derive a multiuser convex optimization problem to find the optimal allocation of subchannels, and propose a lowcomplexity adaptive subchannel allocation algorithm. Simulation results show that the proposed algorithm performs almost as well as the optimal solution. Also, higher spectral efficiency is achieved for larger number of users in a cell due to the multiuser diversity. I.
Large wireless networks under fading, mobility, and delay constraints
 in Proc. IEEE INFOCOM, Hong Kong
, 2004
"... Abstract — We study wireless ad hoc networks with a large number of nodes, following the line of investigation initiated in [1] and continued in [2]. We first focus on a network of n immobile nodes, each with a destination node chosen in random. We develop a scheme under which, in the absence of fad ..."
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Cited by 89 (7 self)
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Abstract — We study wireless ad hoc networks with a large number of nodes, following the line of investigation initiated in [1] and continued in [2]. We first focus on a network of n immobile nodes, each with a destination node chosen in random. We develop a scheme under which, in the absence of fading, the network can provide each node with a traffic rate λ1(n) =K1(n log n) − 1 2. This result was first shown in [1] under a similar setting, however the proof presented here is shorter and uses only basic probability tools. We then proceed to show that, under a general model of fading, each node can send data to its destination with a rate λ2(n) = K2n − 1 2 (log n) − 3 2. Next, we extend our formulation to study the effects of node mobility. We first develop a simple scheme under which each of the n mobile nodes can send data to a randomly chosen destination node with a rate λ3(n) =K3n − 1 2 (log n) − 3 2,andwith a fixed upper bound on the packet delay dmax that does not depend on n. We subsequently develop a scheme under which each of the nodes can send data to its destination with a rate λ4(n) =K4n d−1 2 (log n) − 5 2, provided that nodes are willing to tolerate packet delays smaller than dmax(n) < K5n d, where 0 <d<1. With both schemes, a general model of fading is assumed. In addition, nodes require no global topology or routing information, and only need to coordinate locally. The above results hold for an appropriate choice of values for the constants Ki, and with probability approaching 1 as the number of nodes n approaches infinity.
Capacity of Rayleigh Fading Channels under Different Adaptive Transmission and . . .
 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
, 1999
"... We study the Shannon capacity of adaptive transmission techniques in conjunction with diversity combining. This capacity provides an upper bound on spectral efficiency using these techniques. We obtain closedform solutions for the Rayleigh fading channel capacity under three adaptive policies: opti ..."
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Cited by 86 (7 self)
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We study the Shannon capacity of adaptive transmission techniques in conjunction with diversity combining. This capacity provides an upper bound on spectral efficiency using these techniques. We obtain closedform solutions for the Rayleigh fading channel capacity under three adaptive policies: optimal power and rate adaptation, constant power with optimal rate adaptation, and channel inversion with fixed rate. Optimal power and rate adaptation yields a small increase in capacity over just rate adaptation, and this increase diminishes as the average received carriertonoise ratio (CNR) or the number of diversity branches increases. Channel inversion suffers the largest capacity penalty relative to the optimal technique, however, the penalty diminishes with increased diversity. Although diversity yields large capacity gains for all the techniques, the gain is most pronounced with channel inversion. For example, the capacity using channel inversion with twobranch diversity exceeds that of a singlebranch system using optimal rate and power adaptation. Since channel inversion is the least complex scheme to implement, there is a tradeoff between complexity and capacity for the various adaptation methods and diversitycombining techniques.