Multiuser OFDM Capacity Analysis with Partial Channel Information Multiuser Wireless Communications Course Project

This paper studies multiuser orthogonal frequency division multiplexing (OFDM) system using adaptive subchannel and power allocation with partial channel information. Previous research on multiuser OFDM includes margin adaptive (MA) optimization and rate adaptive (RA) optimization. The capacity gain using adaptive resource allocation over fixed resource allocation such as time division multiple access (TDMA) and frequency division multiple access (FDMA) was evaluated. However, all the previous work assumes perfect channel information available at the base station. In reality, system delays (such as processing time, channel information collection time, etc) are unavoidable. Only partial/sampled channel information is available at the base station. The delays make the current subchannel and power allocation scheme not optimal to the current channel condition. While the maximum Doppler frequency spread captures the channel variation speed, the capacity of dynamic multiuser OFDM system with partial channel information vs. Doppler frequency is simulated in this paper. In addition, since it is not possible to solve the optimization problem on-line, suboptimal algorithms are always of interest. In this paper, a new suboptimal algorithm to solve the rate adaptive optimization problem is developed.