Td-scdma Smart Antenna Design

TD-SCDMA as one of the 3rd generation standard, two key technologies have been adopted, i.e. Smart antenna and joint detection.The meanings of smart antenna to TD-SCDMA system are listed as below.1,The received signal level has been improved by maximal ratio combining of signal power from multiple antenna paths, and the received signal SNR has been improved by array signal processing, thus the uplink receiving sensitivity will be enhanced accordingly.2,The received and transmitted signal of different user can get high space directivity by beam forming, thus the interference between different users can be isolated and restrained in space.3,The space isolation of different users by beam forming will enhance the capacity of CDMA system, combine with the joint detection, it makes TD-SCDMA the only one 3G technology can use full code resource (a code resource limited system).4,The angular aperture of broadcasting channel can be adjusted by beam forming algorithm, it makes the cell broadcasting coverage can be adjusted by software be possible in TD-SCDMA network optimization. It improves the efficiency and reduces the cost. The angular aperture of traditional antenna can not be adjusted, thus the cell broadcasting coverage adjustment has to be done by antenna replacing.5,Downlink signal can point to user directly by beam forming, it equivalent to improve the downlink power of transmitter, thus the power requirement to the amplifier can be reduced.6,The high power linear amplifier used in CDMA system is the most expensive component, the high power linear amplifier can be replaced by multiple low power linear amplifiers in smart antenna system. Thus the manufacturing cost will be reduced significantly.The smart antenna technology gets comprehensive application in TD-SCDMA and even in LTE evolution. This thesis will focus on the study of smart antenna algorithm theory, algorithm performance improvement, and antenna miniaturization improvement.