Variable spreading factor orthogonal polyphase codes for constant envelope OFDM-CDMA system
Yingming Tsai, Guodong Zhang, Xiaodong Wang · 2006
Novel orthogonal polyphase codes with constant envelope design for OFDM-CDMA system are proposed in the paper. The proposed codes can support large number of users and variable spreading factor like Hadamard codes. Proposed orthogonal polyphase codes not only have better periodic auto- and cross correlations than Hadamard codes but also have constant envelope properties which is preferred for uplink/reverse link transmission. New transmitter and receiver architecture and MMSE receiver are proposed for the OFDM-CDMA system using the proposed polyphase codes. Simulation results show that OFDM-CDMA system using proposed polyphase codes has better PAPR and BER performance than OFDM-CDMA system using Hadamard codes and OFDMA system