The DS/CDMA system using transmission diversity for indoor wirelesscommunications

摘要

In multipath fading channels, the direct-sequence spread spectrum(DS/SS) technique is often employed because of the capability to resolvesignals from different paths and realize path diversity at the receiver.This advantage of DS/SS, however, is only when the time difference ofpropagation delay between paths is greater than a chip duration. Inindoor communications, the delay spread is often very small and theabove condition on the delay and chip duration is no longer satisfied,and this performance improvement by the path diversity with conventionalDS/SS systems cannot be expected. In this paper we propose a newdiversity technique for indoor wireless communication systems wheredelay spread is smaller than a chip duration. In this system, thetransmitter sends signals at the same time from multiple antennas withintentional time delays, which allow a receiver to distinguish andcombine the signals from different antennas