A Channel Equalization Technique on a Time Division Duplex CDMA/TDMA System for Wireless Multimedia Networks

Yukitoshi SANADA
Kazuhiko SEKI
Qiang WANG
Shuzo KATO

IEICE TRANSACTIONS on Communications   Vol.E78-B    No.8    pp.1105-1116
Publication Date: 1995/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Technologies for High-Speed Mobile Communications)
channel equalizer,  time division duplex,  TDMA,  CDMA,  multimedia network,  

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A channel equalization technique on a time division duplex CDMA/TDMA system for wireless multimedia networks is investigated, and the bit error rate performance of the system is theoretically analyzed. The assumed network connects mobile terminals to a node of ATM based high speed LAN through a radio central unit. Only human interface facilities are implemented into the terminal so that users access integrated services through the node of the network. The uplink (from a mobile terminal to a radio central unit) employs a CDMA scheme to transmit human interface signals and the downlink employs a TDMA scheme to transmit display interface signals. Both the CDMA and the TDMA signals occupy the same frequency band. To mitigate bit error rate degradation due to fading, the radio central unit estimates the impulse response of the channel from the received CDMA signals and subtracts the replica signal to cancel the major intersymbol interference (ISI) component. Numerical results using the Nakagami-m fading model and recent propagation measurements show that the proposed TPC technique compensates the fading attenuation and the proposed CEQ cancels the major ISI component. The bit error rate performance of the downlink with the proposed CEQ is superior to that with the DFE by 12dB of the symbol SNR at the BER=10-6 over a specular channel, and the system with the proposed CEQ achieves a BER=10-6 at the symbol SNR=12dB. Furthermore, the channel equalizer is implemented without increases in complexity of the terminal because all the processing on the equalization is carried out only in the radio central unit.