Improvements in code-division multiple access (CDMA) system channel capacity with use of adaptive filters
Kuttichira, Alexander T.
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The capacity of code-division multiple access (CDMA) system is affected by the performance of the receiver system. The accuracy and error-free abstraction of the desired signal from the interfering signals of co-channel users and additive Gaussian noise of the transmission media affects the capacity of the system. Adaptive filters are used to enhance the receiver to decorrelate the desired signal by making use of the orthonormal vectors. The orthonormal vectors are generated with the use of adaptive filters as Least Mean Square (LMS) and normalized Least means Square (NLMS). Also, this thesis considered the use of cyclically shifted filter banks (CSFB) in conjunction with the adaptive filters to study the effects of the reduced computation as the number of users are increased. The statistically independent radio channel indoor model (SIRCIM) medium was used for transmitting the signal. Users from 5 to 25 were used for the performance analysis. The performance of the system degraded as the receiver model was loaded as the number of users. The adaptive filters considered were able to successfully extract the desired users signal space for up to 15 users.