The Research Of4G MIMO Smart Antenna System

With the development of the world and advance in technology, the thirdgeneration of wireless communication has great strides forward to the fourthgeneration communication, the number of mobile phone users such as the basiccommunication tool is very large. With the development of data communication andmultimedia service demand, adapt to the mobile data, mobile computing and mobilemultimedia operation of the fourth generation mobile communication began to rise,and there is good reason to expect that the fourth generation mobile communicationtechnology brings people a better future.4G communication technology is not from the communication technology in thepast, but by the traditional communication technology as the foundation, and the useof some new communication technologies to improve the efficiency of the networkand wireless communication function. With the continuous growth of cellular mobileusers, how to solve the spectrum scarcity, restrain all kinds of interference, improvethe quality of the service has become an urgent problem to be solved. Therefore,people put forward a series of solutions. For example, encoding technology into microcellular technique, frequency hopping technology, efficient in communicationintensive place and power control. Although the application of various newtechnologies can solve part of the problem, the fundamental limitations of whichcould not be eradicated, provide a new way for smart antenna in order to solve allthese problems.Smart antenna can be used widely, the reason of most fundamental and core isbecause it uses orthogonal frequency division multiplexing OFDM technology, it willbe a wide carrier channel is divided into several orthogonal sub-channel, used totransmit data in parallel. One of its characteristics is that can effectively reduce themultipath fading effect on the system. Because of the need to send the signal parallelmodulation to each sub-carrier, each subcarrier among not only to maintain theorthogonality of strict, and to reduce the synchronization error at the receiver and transmitter in between, so how to solve the synchronization error is each wirelesscommunication system designers must consider the problem. Despite the device itselfcan not overcome the asynchronous factors, system frequency shift brought not thesynchronization problem becomes before communication system design have greatimportance.Through the research of the smart antenna system, maybe we can come to themain line, in order to improve the stability of the smart antenna system, then we mustguarantee the stability of the application of OFDM technology; by reducing thesystem synchronization error is an important way to solve. In order to reduce theinfluence of synchronization error on the system caused by the frequency shiftcharacteristics, analysis of the system is the key in the design stage.In order to study the smart antenna system, First, introduced the background andcurrent situation of the development of smart antenna. Then introduces the basicknowledge of smart antennas, antenna and antenna array advantage now mainstreamapplication application. Then introduces the MIMO smart antenna for transmittingwave arrival direction estimation. Then introduces the system model of combinationof MIMO-OFDM technology, points out that the influence of frequency offset onsystem caused if ignore, will deteriorate the system performance index. At the end ofthe spectrum shift to the system caused by the impact is analyzed and simulated. Thesimulation results show that the effect of frequency offset on system, the very big,must be controlled, otherwise it will bring disastrous consequences for the wirelesscommunication system. So I think that in the initial stage of the smart antenna design,frequency shift analysis system is how to raise the necessary conditions of thestability of the system.The research work of this paper provides certain reference on the how to designscheme of4GMIMO smart antenna system.