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

提出了一种新的数字移动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验证了其抗延迟扩展的性能。本项目的目的是在一个复杂多径时延分布的实际城市地区，对DSK高速数字移动数据传输进行可行性研究。主要研究结果如下：为了进行比较，实现了高达1mbps的DSK和BPSK的发射器和接收器。调制器为正交型，基带波形存储在ROM中。解调器是用SAW作为延迟元件的差分检测器。在实验室实验中，还实现了30秒的延迟模拟器。在京都进行的现场测试表明，只要多径延迟小于半比特间隔，DSK就具有优越的误码率。京都大学校园内的数据传输速度为512 kbps，京都大学附近街道上的数据传输速度为128 kbps，这是可以接受的，而bpssk则不行。结果表明，指令天线可以有效地抑制长延迟信号，从而提高DSK和BPSK的误码率。因此，DSK与天线方向分集接收相结合似乎是高速移动数据传输系统的理想选择。在京都的不同地点测量了多径延迟剖面，并阐明了一般特征。查明了造成长时间延误的主要原因。分析了延迟时间与误码率之间的关系，发现在普通调制方案中，在50- 100kbps以上的数据速率下存在长延迟信号时，误码率不会低于10^<-3>，误码率会下降到10^<-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.