Smart Antennas In Wireless Communication Systems

In recent years,the wireless communication technique has developed rapidly. CDMA becomes the key technique to realize the 3rd generation mobile communication,and has been widely used.With the rapid increase of social information demand and the fast popularization of individual mobile communication,frequency has become more and more valuable.In order to hold more users in a limited frequency,many technique is proposed,among which smart antenna is the research hotspot.Smart antenna adopts SDMA, and in terms of the difference of transmission direction,it can distinguish signals of the same frequency and the same time interspace.Smart antenna can enlarge cacacity greatly ,and has become a key research topic of many countries nowdays.This dissertation makes a detailed introduction of smart antenna in the wireless communication system,mainly in the CDMA system,and the influence of smart antenna on CDMA system capacity is also analyzed.The dissertation is made up of six chapters:Chapter 1 simply discusses the history of wireless communication and the three criteria of CDMA,and introduces smart mobile communication technique.Chapter 2 embodies smart antenna technique.Two types of smart antenna are introduced:beam-switched system and adaptive antenna system.Then the spatial processor is discussed.Some classical optimization beamforming schemes and adaptive algorithms are also presented.Chapter 3 investigates the capacity improvement in CDMA multi-cellular system with base-station smart antenna.We consider the effects of multipath interference, thermal noise, path loss, processing gain and voice activity factor.And introduces multiuser detection combined with smart antenna.Chapter 4 discusses an important component of smart antenna technique: time-space coding.We combine time-space coding and blind adaptive multiuser detection to enhance system capacity further.diaper 5 introduces the use of smart antenna based on software radio in CDMA communication system.Chapter 6 narrates the status quo of smart antenna,and also expects its prospect.