A multicarrier CDMA communication system with adaptive transmission power allocation

Abstract

We propose a multicarrier code-division multiple-access (MC-CDMA) system with adaptive transmission power allocation. The transmission power is allocated over M′ strongest subcarriers among M available ones. Using only M′ subcarriers of which channel gains are relatively large indicates that the transmission power to maintain the desired received signal strength can be reduced, but decreasing M′ also lead to a reduction of effective spreading gain to mitigate the multiple access interference. We analyze the trade-off between M′ and effective spreading gain, and find the optimal M′ that minimizes the average bit error rate (BER). Our results show that the BER can be significantly reduced if M′ is properly chosen, and transmit signals over only the strongest subcarrier (M′=1) is the best especially for low SNR regions. © 2012 Springer-Verlag.