Study On Space-Time Coding Techniques For Wireless Telecommunication

The Space-Time Coding (STC) is a new research field of wireless communications in recent years. It is a new channel-coding technique for wireless telecommunication which has multiple antennas. By combining the techniques of signal processing in time and space domains which utilize the space processing of signal and space and time characteristics of channel, STC improves the diversity gain and coding gain remarkably, So STC can increase the capacity of wireless communication greatly. This technique provides a new solution to the problem of efficient transmission in wireless communication.When being decoded, common STC requires channel state information (CSI), i.e. accurate chanel estimates, yet DSTC doesn't require them. Under the circumstances where wireless channels fade very rapidly or the data rate is very high,channel estimates are too hard or too costly to detect, DSTC is required.In this paper the basic conceptions and characters of the wireless channels are introduced firstly, then channel model of MIMO systems;Secondly, we classify space-time coding into two types according to CSI available at both the transmitter and the receiver or not. Space-Time Coding for Coherent system includes Layered Space-Time Coding (LSTC),Space-Time Trellis Coding (STTC) and Space-Time Block Coding (STBC). And Space-Time Coding for incoherent system includes Unitary Space-Time Coding (USTC) and Differential Space-Time Coding (DSTC). The comparison between the three coding is presented.Simultaneously, we present the simulation results of them.STTC is a good coding for the MIMO system, but the decoding complexity of space-time trellis coding increases exponentially as a function.Comparing STBC with STTC, though its performances descended,but its decoding theories is easy,so it is concerned by people. Then we detail their encoding and decoding theories,features,and performances. Also the comparison between them is presented.Simultaneously, we present the examples and simulation results of them; finally, the basic discipline of OFDM, the advantage and disadvantages of OFDM system are introduced in detail, System graphs of space-time code and MIMO-OFDM are given, The performances of space-time code in OFDM system are processed using theory analysis method, And the simulation results of them are given.