C5. Multirate Orthogonal Wavelet Division Multiple Access (OWDMA)

In this paper, wavelet based OFDM-like approach is introduced to provide efficient multi-user with multirate transmission. Orthogonal frequency division multiplexing (OFDM) has been used as a multicarrier technique to combat frequency selective fading effects at high speed wireless communications. OFDM suffers from the use of a cyclic prefix (CP) that is appended to each symbol in order to mitigate the effect of inter-symbol Interference (IS I) and inter-carrier interference (lCI). However, this reduces the spectral efficiency as weil as the power efficiency. On the other hand, OFDMA is used to assign different groups of subcarriers to different users with fixed bit rates, but still cyclic prefix (CP) is appended to each symbol in order to mitigate the effect of ISI and ICI. Our approach is to use a perfect reconstruction based on the discrete wavelet trans multiplexer in OFDM transceiver to counter the degrading effect of ISI, and also conserves bandwidth in both single user and multi users with different bitrates. This system, named Orthogonal Wavelet Division Multiple-Access (OWDMA), does not need the use of CP and hence results in enhanced bandwidth and power efficiencies. Theoretical analysis and simulations compare the performance between OFDMA and OWDMA with different bitrates in different channel conditions.