The Implementation Study Of Transceivers Based On Technology Of Smart Antenna

The traditional multiple access technologies including time division multiple access (TDMA), frequency division multiple access (FDMA) and code division multiple access (CDMA), but the capacity and frequency resource of cellular system have become increasingly difficult to meet the needs of the growing mobile communication business, especially in the multimedia data service. Thus, space division multiple access (SDMA) technology came into solving this problem. Smart antenna can use digital signal processing techniques to generate multiple beams in space for multiple users, each beam being aligned to the arrival direction of some signal automatically, while nulls direction is aligned to the direction of the interference, which can effectively eliminate multiple access interferences and improve system performance.This paper briefly introduces some multiple access technologies and their characteristics, and the history and development of the smart antenna, and related concepts will be described. Then we explained the principles and basic structure of the smart antenna beam-forming in detail. Considering the difference between Least Mean Square (LMS) which is a non-blind algorithm and Constant Modulus Algorithm (CMA) which is a blind algorithm, we propose an improved algorithm called Speed Convergence Least Squares CMA (SCLSCMA) which combines the advantages of the LMS and CMA algorithms, not only improving the convergence rate but also without the need of the reference sequence. Then we shortly discuss the two popular Direction Of Arrival (DOA) estimation algorithms based on the subspace, such as Multiple Signal Classification (MUSIC) and Estimation Of Signal Parameters Via Rotational Invariance Technique (ESPRIT). Comparing the performances between the two algorithms by the simulation results, we get a conclusion that the performance of MUSIC algorithm is superior to that of ESPRIT algorithm. Finally, the implementation study of transceivers based on SA is presented. We discuss the reception principle of CDMA system on base band and propose a simple realization of receiver which uses mid-amble sequence to detect signals and DOA. We also did some research on the two implementations of transmitter, which are beam-forming by phase shifting of carrier and amplitude weighting of base-band signal. The simulation results are present and analyzed.