Paper Info
Title
Power Control for Two User Cooperative OFDMA Channels
Abstract
For a two user cooperative orthogonal frequency division multiple access (OFDMA) system with full channel state information (CSI), we obtain the optimal power allocation (PA) policies which maximize the rate region achievable by a channel adaptive implementation of inter-subchannel block Markov superposition encoding (BMSE), used in conjunction with backwards decoding. We provide the optimality conditions that need to be satisfied by the powers associated with the users' codewords and derive the closed form expressions for the optimal powers. We propose two algorithms that can be used to optimize the powers to achieve any desired rate pair on the rate region boundary: a projected subgradient algorithm, and an iterative waterfilling-like algorithm based on Karush-Kuhn-Tucker (KKT) conditions for optimality, which operates one user at a time and converges much faster. We observe that, utilization of power control to take advantage of the diversity offered by the cooperative OFDMA system, not only leads to a remarkable improvement in achievable rates, but also may help determine how the subchannels have to be instantaneously allocated to various tasks in cooperation. Simulations show that the gain from power allocation is still significant even when the CSI feedback is limited.
Year
DOI
Venue
2013
10.1109/TWC.2012.120412.120030
IEEE Transactions on Wireless Communications
Keywords
Field
DocType
Markov processes,OFDM modulation,decoding,encoding,power control,resource allocation,telecommunication channels,BMSE,CSI feedback,Karush-Kuhn-Tucker conditions,backwards decoding,channel adaptive implementation,channel state information,cooperative OFDMA system,inter-subchannel block Markov superposition encoding,iterative waterfilling-like algorithm,optimal power allocation policies,power control,projected subgradient algorithm,two user cooperative OFDMA channels,two user cooperative orthogonal frequency division multiple system,Achievable rates,OFDMA,block Markov coding,power control,resource allocation,user cooperation
Mathematical optimization,Markov process,Subgradient method,Computer science,Power control,Orthogonal frequency-division multiple access,Real-time computing,Decoding methods,Karush–Kuhn–Tucker conditions,Orthogonal frequency-division multiplexing,Channel state information
Journal
Volume
Issue
ISSN
12
1
1536-1276
Citations 
PageRank 
References 
5
0.45
11
Authors
2
Name
Order
Citations
PageRank
Sezi Bakim1121.32
Onur Kaya210613.85