Abstract:

The application of adaptive technology to the muhiuser OFDM (Orthogonal Frequency Division Multiplexing)system can increase the spectrum usage,reduce the transmission power of the system and optimize the system performance.In this paper.a mathematical model f0r the adaptive bit and power allocation in the muhiuser OFDM system in frequency selective fading channels is proposed,and a rapid sub-optimal adaptive allocation algorithm is presented.According to the estimation of instantaneous channel characteristics,the adaptive allocation algorithm can assign the subchannels and bits for each user in the system to minimize the total transmission power with a given bit error rate.Simulated results show that the proposed algorithm is simple in calculation,high in eficiency and optimal in theory as the optimal scheme.

Key words: allocation strategy , orthogonal frequency division multiplexing, muhiuser, adaptive bit allocation