STUDY OF BASIC HIGH-SPEED TRANSMISSION SYSTEM IN MOBILE MESSAGE COMMUNICATIONS.

高传输比特率的移动消息通信具有成本低、无线电频谱效率高、不侵犯人类隐私等优点，可以作为终极通信的候选。通过室内模拟试验和现场试验，对无差错传输的空间概率进行了分析。得到了以下结果：(1)明确了各种传播参数和系统参数下的比特/包错误率和无差错传输概率的一般特征。使用抗多径调制PSK-RZ是不可避免的。(2)将特定传输时间（SPECIFIC TRANSMISSION TIME）定义为误码率的一个归一化参数，使分组误码率的评估更加容易。(3) PSK-RZ有效时，在适当的CN比值下，可轻松获得99%以上的无差错概率。(4)采用新开发的逐位误差测量方法，分析了误差的发生机理和精细结构。突发误差的发生被限制在深衰减附近的点上，在其他点上很容易实现无差错传输。(5)在PSK-RZ失效的情况下，由于去同步而产生的突发误差在一瞬间消失，最坏情况下无差错概率可达70%。通过重传信号，可以保证90%的概率。(6)为了使无差错传输更容易，实验研究了定向天线的圆极化和极化分集效应、降低衰落和误码率。结合上述结果，手机短信通信的实现是有希望的。

Mobile message communication of high transmission bit rate can be a candidate for the ULTIMATE COMMUNICATION as it has merits of very low cost and very high radio spectral efficiency and moreover it does not invade human privacy. Analyzes on spatial probability of error-free transmission has been made by simmulated laboratory experiments and field tests. The following results are obtained :(1) General characteristics of bit/packet error rates and error-free transmission probability have been made clear for various propagation and system parameters. A use of anti-multipath modulation PSK-RZ is found inevitable for the purpose.(2) A new concept of SPECIFIC TRANSMISSION TIME defined as a normalizing parameter for bit error rates enabled to make evaluation of packet error rates easier.(3) When PSK-RZ is effective, more than 99% of error-free probability can be easily obtained for proper values of CN ratio.(4) The occurrence mechanism and fine structure of errors were analyzed by a newly developed bit-by-bit error measurements. Occurrences of burst errors are limited to the points in the vicinity of deep fade, and error-free transmission is easily attained at other points.(5) In case PSK-RZ is not effective, burst errors due to desynchronization disappear in a moment of msec, and error-free probability of 70% may be obtained for the worst condition. By retransmitting the signal, about 90% of probability is assured.(6) To make error-free transmission easier, circular polarization and polarization diversity effects, reduction of fading and error rates using directional antenna have been studied experimentally.Combining the above results, realization of mobile message communication seems hopefull.