Space-time Code Technique And Receiver Design For Mobile Communications

Space-time processing technique, which has strong points of both time processing and space processing, is considered as one of the most important field of signal processing. Nowadays, mobile communications are rapidly growing around the world and a number of emerging techniques are employed for canceling interference, improving gain, extending coverage, decreasing transmit power and increasing capacity in mobile communication systems. Among these techniques the most exciting and potentially one is the use of space-time processing. This thesis investigates some problems of space-time processing that applies to mobile communications with emphasis on space-time code techniques and receiver design. Space-time code is a signal design technique for transmit diversity with antenna arrays, and maximizes the transmit diversity gain. Because of multi-path and time-varying propagation environment for mobile communication systems space-time code usually combines with channel coding technique. In the thesis the generalized space-time code technique, which combines with channel coding, is treated. Firstly, this thesis discusses mobile communication channel and space-time signal model. Secondly, current studies and future prospects of both space-time processing and space-time code are given. Lastly, we research space-time code technique and receiver design including application of neural networks to space-time code, a transmitter and receiver model employing layered space-time and its performance simulation, the turbo STCM that combine of turbo code and space-time code and its performance. receiver design of multiuser space-time code systems, receiver design of mobile communication system employing space-time processing. The main results are as follows: ? Space-time channel and space-time signal are studied. A kind of model of space-time vector channel is given, and space-time signal is analyzed systemly. Current studies and future prospects of space-time processing techniques with the emphasis from theory to application are discussed. ? According to author抯 opinion the definition of space-time coding is introduced. Then the principle of space-time coding and the capacity of antenna arrays transmit diversity system are discussed from information theory aspect. Also, the strong points and performances of BLAST, STCM and BSTC system are analyzed. ? A new decoding scheme is given based on Hopfield neural networks. The order of the energy function of the Hopfield network is reduced to 2 by means of Trellis diagram and mean field annealing algorithm. It is important improvement compared with previous work published and is implemented easily by hardware. The simulation result shows the decoding performance approaches the ideal MLD. ? A transmitter and receiver model employing layered space-time codes is discussed. Further, encoding methods of layered space-time codes are derived. Also the decoding and receiving scheme using linear Zero-forcing Iv decision-feedback equalizer with linear processing complexity is studied. Lastly. simulation results show good performance and higher spectral efficiency. ? At first, we discuss turbo code modulation technique, and some problems in previous work published are analyzed. Then the turbo STCM that combines turbo code and STCM is driven. We investigate transmit and decode schemes of the turbo STCM. The simulation results compared with...