A Transmission Power Control Technique on a TDD-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.1095-1104
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)
transmission power control,  time division duplex,  TDMA,  CDMA,  multimedia network,  

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A transmission power control technique on a TDD-CDMA/TDMA system for wireless multimedia networks is proposed. The assumed network connects mobile terminals to a node of an 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 (2.4kbit/s) and the downlink employs a TDMA scheme to transmit display interface signals (24 Mbit/s). Both the CDMA and the TDMA signals occupy the same frequency band. To mitigate bit error rate degradation due to the fading, the radio central unit estimates the impulse response of the channel from the received CDMA signals and controls the transmission power of the TDMA signals to compensate the fading attenuation. The bit error rate performance of the downlink with the proposed transmission power control is theoretically analyzed under several fading conditions. Numerical results using the Nakagami-m fading model and recent propagation measurements show that the proposed power control technique compensates the fading attenuation and improves the bit error rate performances. The bit error rate of the downlink is reduced from 10-2 to 10-5 at the symbol SNR of 20dB by employing the proposed transmission power control, which is less sensitive to the severity of the fading. Furthermore, the proposed transmission power control is implemented without increasing the terminal complexity because all the processing on the power control of the downlink is carried out only in the radio central unit.