Performance comparison on wireless access scheme for high data rate transmission in mobile radio

It is necessary to establish high data rate transmission to support multimedia services. This requires a determination of access scheme's performance and a clarification of the selection criteria. We present the transmission performance of a CDMA system with a RAKE receiver. The relationship between the root mean square delay spread normalized by the chip period at a minimum BER and the number of RAKE fingers is evaluated. The BER performance of CDMA multi-code transmission is also evaluated. It is found that single code transmission has a better performance than multi-code transmission. The BER performance of a TDMA system with an equalizer is also presented. It is found that as the number of combined symbols becomes larger the root mean square delay spread normalized by the symbol period at the minimum BER increases. The TDMA system BER performance is compared with the CDMA system performance. For example, when the processing gain is 16, the number of RAKE fingers is 4, and the number of combined delayed symbols in the equalizer is 4, if the root mean square delay spread normalized by the information symbol period is larger than 0.27, TDMA offers a better BER performance.