Development And Design Of Two Broadband Wireless Communication Systems

Recently, Broadband Wireless Access Network (BWAN) has attracted great attention in the telecommunication industry. Various standards and applications came forth in the past several years. In this thesis, we investigate some key engineering problems on the latest 3.5GHz broadband wireless access systems.In the literature, a lot of techniques have been implemented in the new generation BWAN to improve the spectrum efficiency, link reliability, and system flexibility. Among them, digital modulation and demodulation are one of the core methods to ensure the aforementioned goal, which will be discussed in detail in this thesis. The digital modulation and demodulation technique described here could not only improve the performance of QAM signals, but also realize the variable-rate modulation and demodulation. Moreover, combined with digital baseband signal processing with FPGA, we could develop various wireless communication systems on a typical hardware platform.The author analyses the principles of digital modulation and demodulation, and other related techniques. A digital modem--STEL-2176 is developed and implemented in two practical systems: 3.5GHz BWAN system and Multiband Point to Point microwave communication system. Meanwhile, detailed overall system design and management, subsystem design, and system test are described in the thesis. Also, the method of digital modem realization and other applications are analyzed.The systems described in the thesis are developed based on ASIC, which caused certain limits in further complicated applications. Thus, we point out that general digital modems developed on FPGAs and DSPs have a promising future.