| The demand of wireless communication systems has exploded throughout the world. The limitation of the bandwidth available for those systems has created problems which all wireless providers are working to solve. Furthermore, a complex multipath propagation environment, limited battery lifetime, larger cell-coverage, lower infrastructure and operating costs, and high data rate services are other problems that a wireless system engineer has to face. In seeking schemes solving these problems, researchers have turned their attention to adaptive smart antenna systems which employ antenna arrays coupled with signal processing at the base station. By exploiting the spatial dimension, adaptive smart antenna systems allow multiple mobile terminals to transmit co-channel signals, thereby increasing capacity, and extending cell-coverage. To operate effectively, adaptive smart antenna systems should be capable of estimating the array response vector which represents the unique propagation pattern between the mobile terminal and the antenna array at the base station. Once the array response vector is estimated, we can design a beamforming weight vector to recover the transmitted signal. The uplink array response vector can even be used as a downlink weight vector in time-division-duplex (TDD) systems. It has been shown that the singular value decomposition (SVD) method provides a good estimate of the array response vector. This decomposition is based on the sample covariance matrix of the received data at the base station. For N samples and an M-element array antenna, it requires O(NM2 ) computational complexity to calculate sample covariance matrix and O(M3) for the decomposition. Even though the performance of the SVD method is good in general, the computational cost may not be practical for real time implementation.; In this dissertation, we propose a fast algorithm for the estimation of the array response vector which requires about O( NM2) computations. Statistical analysis of the array gain using the proposed estimation algorithm is performed for a single mobile terminal case. Experiment measurements were also performed to validate the proposed method using the smart antenna testbed. Application of the proposed method is also extended to a multiple mobile terminal case for uplink adaptive smart antenna system making use of code division multiple access (CDMA). Using the channel parameters given by the International Telecommunication Union (ITU) for third generation (3G) cellular standardization, indoor and vehicular test environments are considered. |
