A TRANSMISSION POWER-CONTROL TECHNIQUE ON A TDD-CDMA TDMA SYSTEM FOR WIRELESS MULTIMEDIA NETWORKS

A transmission power control technique on a TDD-CDMA/TDMA system for w ireless multimedia networks is proposed. The assumed network connects mobile terminals to a node of an ATM based high speed LAN through a ra dio central unit. Only human interface facilities are implemented into the terminal so that users access integrated services through the nod e of the network. The uplink (from a mobile terminal to a radio centra l unit) employs a CDMA scheme to transmit human interface signals (sim ilar to 2.4 kbit/s) and the downlink employs a TDMA scheme to transmit display interface signals (similar to 24 Mbit/s). Both the CDMA and t he TDMA signals occupy the same frequency band. To mitigate bit error rate degradation due to the fading, the radio central unit estimates t he 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 wit h the proposed transmission power control is theoretically analyzed un der several fading conditions. Numerical results using the Nakagami-m fading model and recent propagation measurements show that the propose d power control technique compensates the fading attenuation and impro ves the bit error rate performances. The bit error rate of the downlin k is reduced from 10(-2) to 10(-5) at the symbol SNR of 20 dB by emplo ying 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 complexit y because all the processing on the power control of the downlink is c arried out only in the radio central unit.