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

大时延时延的多径传播会导致高比特率移动无线电通信系统误码率的严重下降。因此，多径时延的测量对于估计传输质量是非常重要的。然而，测量多径延迟时间通常是非常困难的。通常采用宽带伪随机噪声序列的传输和滑动相关技术的接收来测量多径时延分布。这使得延迟时间的测量变得昂贵和耗时。在这项研究中，我们开发了一种非常简单，但方便的在役多径延迟扩展测量设备，用于高速数字移动通信。主要研究结果如下：(1)通过简单地测量差分检测器的正交通道检测器对BPSK信号的输出，可以估计出延迟扩展。(1)对于一个pi/4位移的QPSK信号，通过简单地测量同相通道和正交通道检测器输出的幅值之差，可以估计出延迟扩展。这两种测量电路都很容易实现。对于这两种情况，测量的输出都显示与误码率性能很好地对应。同信道干扰或载波干扰比（C/I）也可以用相同的电路测量。这是特别有用的决策标准，为内部细胞间的移交。即使在多径延迟扩展和同信道干扰并存的情况下，测量输出仍然被证实是一个很好的误码率性能指标。

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.