Development of in-service measurement equipment of multipath delay time for-high rate TDMA mobile communication

点击翻译按钮获取中文摘要

Multipath propagation with large delay time difference causes severe bit-error-rate degradation of high bit-rate mobile radio communications system. Thus, the measurement of multipath delay time is very important to estimate the transmission quality. However, it has been generally very difficult to measure multipath delay time. Transmission of a broadband pseudo-random noise sequence and reception by sliding correlation technique are generally used to measure multipath delay profile. This makes the measurement of delay time to be costly and timeconsuming.In this research, we developed a very simple, yet convenient in-service multipath delay spread measurement equipment for high-rate digital mobile communication. The major results are summarized as follows :1. (1) By simply measuring a quadrature channel detector output of a differential detector for a BPSK signal, delay spread can be estimated.2. (1) By simply measuring the difference between magnitudes of in-phase channel and quadrature channel detector outputs for a pi/4-shifted QPSK signal, delay spread can be estimated.3. Both measurement circuits were shown to be implemented very easily.4. For both cases, measured outputs were shown to well-correspond to the bit-error-rate performance.5. Co-channel interference or carrier-to- interference ratio (C/I) is also found to be measured by the same circuits. This is especially useful as a criterion of decision making for intrand inter-cell handoff.6. Even when multipath delay spread and co- channel interference co-exist, still the measured output was confirmed to be a good measure of bit-error-rate performance.