Optimal resource allocation in the OFDMA downlink with imperfect channel knowledge

• Published in: IEEE transactions on communications Vol. 57; no. 1; pp. 232 - 241
• Main Authors: Wong, I.C., Evans, B.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Availability; Broadband communication; Channel estimation; Channel state information; Channels; Computer simulation; Delay; Delay effects; Delay estimation; Detection, estimation, filtering, equalization, prediction; Downlink; Exact sciences and technology; Feedback; Frequency conversion; information rates; Information, signal and communications theory; Maximization; multiaccess communication; Multiplexing; OFDM modulation; Optimization; Organization, operation and development plans; orthogonal frequency division multiple access (OFDMA); radio spectrum management; Radiocommunications; Resource allocation; Resource management; Signal and communications theory; Signal, noise; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); uncertain systems; Parameter estimation; Bit error rate; Resource allocation; Frequency division multiple access; Information rate; Downlink; Subcarrier; Optimization; multiaccess communication,radio spectrum management; Uncertain system; information rates; Optimal allocation; Channel estimation; Delay time; Radio spectrum; Availability; Multiple access; Estimation error; Optimal algorithm; uncertain systems; Frequency allocation; Wide band transmission; Ergodicity; Broadband communication; Information transmission; Simulation; Orthogonal frequency division multiplexing; orthogonal frequency division multiple access (OFDMA); Resource management
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2009.0901.060546

Previous research efforts on OFDMA resource allocation have typically assumed the availability of perfect channel state information (CSI). Unfortunately, this is unrealistic, primarily due to channel estimation errors, and more importantly, channel feedback delay. In this paper, we develop optimal resource allocation algorithms for the OFDMA downlink assuming the availability of only partial (imperfect) CSI. We consider both continuous and discrete ergodic weighted sum rate maximization subject to total power constraints, and average bit error rate constraints for the discrete rate case. We approach these problems using a dual optimization framework, allowing us to solve these problems with O(MK) complexity per symbol for an OFDMA system with K used subcarriers and M active users, while achieving relative optimality gaps of less than 10 -5 for continuous rates and less than 10 -3 for discrete rates in simulations based on realistic parameters.