Field Study of Anti-Multipath Modulation Technique for High-Speed Digital Mobile Radio

本文提出了一种新的数字移动的无线电抗多径调制技术--双相移键控（DSK），并通过计算机仿真和实验室测量证实了其抗延迟扩展性能。本研究的目的是在一个具有复杂多径延迟分布的实际城市区域中，利用DSK进行高速数字移动的数据传输的可行性研究。主要研究结果如下：1. DSK高达1 Mbps和BPSK的发射机和接收机，用于比较。调制器为正交型，基带波形存储在ROM中。解调器是以SAW作为延迟元件的差分检波器。一个延迟模拟器长达30秒也实现了实验室实验。根据在京都的现场测试，只要多径延迟小于半比特间隔，DSK就显示出优越的误码率。京都大学校园内以512 kbps的数据传输和京都大学附近街道上以128 kbps的数据传输是可以接受的，但对于BPSK则不然。3.实验结果表明，定向天线可以有效地抑制长时延信号，从而改善DSK和BPSK的误码率。因此，DSK与天线方向图分集接收相结合是高速移动的数据传输系统的一个很有前途的选择.在京都的不同地点测量了多径延迟曲线，并阐明了一般特性。查明了长期拖延的主要原因。分析了延迟时间与误码率之间的关系，发现对于普通调制方案，当数据速率大于50-100 kbps时，如果存在长延迟信号，误码率将不会降到10 μ <-3>s以下，最高可降到10 μ s<-1>。

We have proposed a novel anti-multipath modulation technique double phase shift keying (DSK) for digital mobile radio and confirmed its delay-spread-resistant performance by computer simulation and laboratory measurements. The purpose of this project was to make a feasibility study of high speed digital mobile data transmission using DSK in an actual urban area with complicated multipath delay profiles. Main results are as follows:1. Transmitters and receivers of DSK up to 1 Mbps and also BPSK, for comparison, were implemented. Modulators are of quadrature type with baseband waveforms stored in ROM's. Demodulators are differential detectors with SAW as delay elements. A delay simulator up to 30 sec was also implemented for laboratory experiments.2. According to the field tests in Kyoto, DSK showed superiof bit-error-rate so long as the multipath delay is less than a half bit interval. Data transmission at 512 kbps within Kyoto Univ Campus and at 128 kbps on the streets near kyoto univ was acceptable, while not for BPSK.3. A directive antenna was confirmed to be effective to suppress the long-delayed signal, and thus to improve bit-error-rate for both DSK and BPSK. Therefore, combination of DSK and the antenna pattern diversity reception seems to be a promising candidate for high speed mobile data transmission system.4. Multipath delay profiles were measured at various locations in Kyoto and general characteristics were clarified. The major causes of long delay were identified. The relation between delay time and error rate was analyzed and it was found that error rate never fell below 10^<-3> and got degraded up to 10^<-1> if long delayed signals existed at data rates above 50-100 kbps for ordinary modulation schemes.