Turbo Product Code Techniques And Their Applications In Beyond Third Generation Mobile Communication Systems

With the increasing demand for high-speed services in beyond third generation(B3G) mobile communication systems, forward error correction(FEC) codes and signal processing techniques are receiving much attention.This dissertation focuses on a sub-class of iterative turbo-like FEC codes called turbo product code(TPC) whose theory and applications in B3G mobile communication systems are studied.It is known that orthogonal frequency division multiplexing(OFDM),multiple-input multiple-output(MIMO) and their combination are critical technologies in B3G mobile communication systems. The first objective of this research is the introduction of the encoding and decoding principles of turbo product code(TPC).The block diagram of parallel iterative decoding of TPC is proposed.In terms of encoding, TPCs belongs to product codes.From the point of view of decoding,TPC is the extension of Turbo code. A TPC is a multidimensional array of block codes.It is a large code built from two,three,or many smaller block codes.This dissertation compares several hard-decision and soft-decision decoding algorithms proposed in seedtime of product codes,which take different implementation complexity and error-correcting performance.But the iterative soft-input soft-output decoding algorithm is adapted to TPCs. Furthermore,this dissertation compares a potential parallel iterative decoding method and the conventional serial decoding scheme of TPCs. TPCs offer a wide range of flexibility in terms of performance,complexity,and code rate.Moreover,TPCs do not suffer from the error floor associated with Turbo codes below BER of 10-5.Therefore,TPCs are well-suited to be implemented as an advanced FEC channel encoding technique for the performance improvement of future B3G mobile communication systems. From the BER aspect,TPC application areas are also presented in this study of B3G mobile communication systems.The ideal channel estimation and accurate synchronization are assumed in all these applications. The first application research area is the combination of TPCs and space-time block codes(STBCs). The small-scale propagation model in the wireless channel is analysed to enhance the whole understanding of wireless communication systems.These analysis plays an important role in building wireless communication systems.The flat Rayleigh fading channel belongs to small-scale fading channels ,which combines the frequency selective nature and statistical time varying nature of the received signal envelope. The flat Rayleigh fading channel is not only a widely applied simple model,but also it builds up frequency selective fading channels such as IMT-2000 channels. Then this dissertation introduces constructions and properties of STBCs. The proposed system is applied to MISO Rayleigh flat fading channels.The system total frequency spectral efficiency is constant by means of adjusting the modulator and the code rate of STBC. STBCs are not designed to achieve an additional coding gain although their encoding and decoding schemes are very simple. Simulation results show that the system performance is improved by concatenation of TPC and STBC . The second application research area is that turbo product code is applied to coded OFDM system.This is so called single user SISO(Single-Input Single-Output)-OFDM system.Then this dissertation analyses the time-frequency structure of OFDM symbols and the basic OFDM model.The proposed system is applied to IMT-2000 channels for a uplink user. Simulation results show that the system offers Bit Error Rate of 10-6 at Eb/N0 >15dB. The last section of this dissertation presents a STBC coded MIMO-OFDM system based on TPCs,in which STBC is adapted to a MIMO implementation scheme.In frequency selective fading channel,conventional MIMO systems are damaged by intersymbol interference.Hence, MIMO technologies are applied to OFDM systems,further applied to broadband channels.The channel frequency response of systems with multiple transmit antennas and multiple receive antennas is analysed. The dissertation depicts a STBC coded MIMO-OFDM simulation system with 2Tx(transmit antenna) and 2Rx(receive antenna).In addition,the channel capacity properties of system with the MRC receive diversity isdeduced,these properties can also be used for STBC coded MIMO-OFDM systems. The proposed system is applied to IMT-2000 channels.Simulation results show that the code rate of TPC and IMT-2000 channel types play an important role in the BER performance.This original research gives a communication designer a reference for building adaptive coded modulated MIMO-OFDM system.