Adaptive Power Control for 4G OFDMA Systems on Frequency Selective Fading Channels
Future cellular radio systems aim at maximizing the spectral efficiency. OFDMA radio resources are the scarce good with their dimensions bandwidth, time and space. Due to frequency selective fading the effective path-loss varies in all dimensions. Adaptive algorithms are available which allocate the best modulation and coding scheme depending on the expected SINR, as well as dynamic sub-channel assignment which aims to choose the best sub-channel for each user. This already boosts the performance of OFDMA system. However, these algorithms alone do not touch the transmitted power per sub-channel. On the cell edge this is fine, but large areas are covered with a transmitted power exceeding the usually required SINR.