Study On Digital Wireless Voice Transmisstion System Based On TDD Technolodge

The applications of mobile communication systems based on TDD technology are still fewer. But this situation will be improved because the TDD technology will be emphasized and more important than ever as the TD-SCDMA standard, which is one of 3G standards and whose intellective property right belongs to China, is becoming to maturity. In the other hand, the voice communication is always the important mode during the development of wireless communication, and its application area is keeping wider and wider. The interphone in the trunking communication system is one of usual applications based on voice transmission. The digital wireless voice transmission system based on TDD technology is studied in this thesis. TDD technology has many advantages, such as less wireless resource to be occupied, supporting asymmetry services, lower cost equipment relatively, easier to be implemented, and so on. So that TDD technology can provide an economical resolvent for wireless communication systems. The resolvent for the terminal of the digital wireless interphone is studied in this thesis, which is combined with the technologies of wireless communication, microcontroller and voice coding, etc.The terminal mainly consist of the MSP430 chip, which is a kind of ultra low power and 16-bit RISC singlechip, being the terminal's micro control unit, the CMX649 voice codec, which can successfully serve in a wide range of voice coding applications, and the CC1000 RF chip. The air interface protocol and the method of how to implement TDD are studied following the scheme and model of system, and the software of system is be designed then. The scheme of voice coding is studied in the end of this thesis, and the Continuously Variable Slope Delta (CVSD) Modulation is chose. CVSD is an ideal voice coding scheme for wireless applications due to its robust performance in the presence of bit errors. The result from the simulation through the computer can also indicate that CVSD is fit for the system studied in this thesis.The digital wireless voice transmission system studied in this thesis has the TDD feature, so it can provide another resolvent based on TDD for the trunkingcommunication system. Besides, if the system is based upon low cost and low power consumption, and has been perfected its functions, it will serve and popularize in a wide area.