| New wireless communication methods have been enthusiastically adopted throughout the world. The majority of current and proposed wireless communication systems employ the multiple access method of TDMA or CDMA in combination with frequency reuse or FDMA. In late 1970s, the first TDMA system was used for satellite communication. In late 1991, a cellular system based on TDMA was adopted in second-generation mobile radio systems. TDMA will occupy a place in third generation mobile radio systems. The CDMA originated in spread spectrum communications for military purpose in 1960s. A cellular system based on CDMA (IS-95) had been developed and successfully deployed. In future third generation mobile radio systems, the dominant multiple access scheme is CDMA. This research concentrates on TDMA, CDMA systems and some key technologies. The value of the research resides in its practicable solutions to problems in engineering projects.Under severe receiving conditions, for example the lower SNR (Signal to Noise Rate), there is a high error rate of UW (Unique Words) detecting for TDMA system by conventional detecting methods. A missing or false UW detecting will result in the loss of all data in one frame because UW operates as a marker of a frame beginning. In order to improve detecting probability of UW, an UW detecting method working at low SNR is developed. Again, in cellular systems based on CDMA, a receiver that is located at another position in the vicinity of the base station will bear more MAI (Multiple Access Interference) than idealized position. Considering that spread sequences and data of other users cannot be also attained, the space division receiving could be a simple and effective method to reduce MAI. Then, a RAKE receiver that is fit for such cases is designed. There are manyspecifications of TDMA systems, and therefore a universal TDMA terminal is proposed to accommodate to wide variety of signal forms and rapid development. Finally, this dissertation describes a new low cost practical QS-CDMA-WLL (Quasi-Synchronous CDMA Wireless Local Loop), which is used to provide basic services of voice and data or is used as special wireless data network.The primary work and novelty in this dissertation resides in: 1) The UW detecting work at low SNR has been studied on the basis of maximum likelihood estimation techniques after analyzing and comparing various detecting methods of other's progeny. The analysis and simulation results made evidence that the new method proposed attains gain by about 1.5 to 2dB as compared with correlation detecting by soft-decision, 2.5 to 3.5dB compared with hard-decision detecting, under conditions of coherent demodulation, UW length of 16bits, 3bits quantized input data, window width of 9bits and AGWN channel. The universal high speed UW detecting structure developed has been put to practice. It improves on UW detecting performance of traditional methods in which error rate of detecting is higher. The test results agree well with analyses and simulations. A new scheme combining with data structures in frames is proposed to improve further detecting performance. 2) The new universal TDMA receive terminal equipment has been developed. Its working parameters such as frame structures can be set or change by serial communication port of personal computer. Some modules of it such as demodulator, decoder and so on can be substituted with different parameters optional plug-in parts to be used for different signal specifications. This equipment worked well in actual communication systems. Another new advanced solution for implementing TDMA receive terminal is presented. This equipment is realized on the basis of preprocessor, PC and local area network. It could be set to rapidly adapt to wide variety of specifications byconfiguring corresponding parameters and downloading relevant processor software. It is under development.3) A RAKE receive structure based on match filter has been designed and implemented to be applied in the space division receive scheme.
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