Title :
Polyphase codes for uplink OFDM-CDMA systems
Author :
Tsai, Yingming ; Zhang, Guodong ; Wang, Xiaodong
Author_Institution :
InterDigital Inc., Melville
fDate :
3/1/2008 12:00:00 AM
Abstract :
We propose a OFDM-CDMA system that employs polyphase codes to support variable spreading factors. A systematic approach for constructing the polyphase code sequences of variable spreading factors is developed. Polyphase codes exhibit better auto- and cross-correlation properties than Hadamard codes. When employed in OFDM-CDMA systems, polyphase codes result in certain structured multiple-access interference (MAI) caused by multipath. Analytical and numerical results show that OFDM-CDMA systems employing polyphase codes have better PAPR performance than those using Hadamard codes. The BER performance of the OFDM-CDMA system using polyphase codes is evaluated by numerical results and compared to that of the OFDM-CDMA system using Hadamard codes with and without clipping.
Keywords :
Hadamard codes; OFDM modulation; code division multiple access; interference (signal); multipath channels; Hadamard codes; cross-correlation properties; multipath systems; multiple-access interference; polyphase code sequences; uplink OFDM-CDMA systems; Error correction; Error correction codes; Fading; Intersymbol interference; Multiaccess communication; Multiple access interference; Multiuser detection; OFDM modulation; Peak to average power ratio; Wireless communication;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2008.050629
