Study On Space-Time Block Coding In Wireless Mobile Communication System

In recent years the space-time coding (STC) method is becoming a new research direction in wireless communication fields. It is a kind of channel coding technology, which based multiple-input and multiple-output (MIMO) systems. It increases not only greatly the capacity of wireless communication systems, which provide diversity gain and coding gain for the wireless transmission, but it is also able to provide the bandwidth efficiency, which is faster than the traditional single antenna systems.Therefore, this technique is intended to provide new solutions to the problem of limited bandwidth and applications based on this technology will be used in the future of wireless communication systems for high speed data transmission.Now the main three kinds of STC have been proposed as layered space-time coding (LSTC), space-time trellis coding (STTC) and space-time block coding (STBC). Thereinto, STBC has obvious superiority on performance and its encoding and decoding are relatively simple. STBC can be combined with many technologies, one of them is combing with OFDM .This thesis investigates these issues related to this hot research topic, the main research results are as follows:1) The encoding and decoding algorithm of STBC is studied in detail in this thesis, including orthogonal space-time block coding and old quasi-orthogonal space-time block coding(QOSTBC). They have simply encoded and decoded algorithm and can achieve full-rate transmission. But the old QOSTBC can't achieve full diversity.2) An appropriate scheme of QOSTBC is studied in this thesis, which based on constellation rotation and matrix rotation. So, the full rate and full diversity gain are not only obtained to optimize the system performance, but also linear decoding is achieved to greatly reduce the decoding complexity.3) In generally, the space-time block coding is studied based on narrow-band wireless communication systems. But the actual wireless mobile communication systems are broadband, which is frequency selective fading. Moreover QOSTBC is combined with OFDM in this thesis, which can avoid restrictions of flat fading in design and implementation of STBC and eliminate inter-symbol interference caused by the multi-path delay. Finally, advantages of this scheme has been shown through simulation and comparison.