Study On Turbo Product Codes In Wireless Fading Channels

Channel coding is one of the key technologies in wireless communication systems, because well channel coding can efficiently improve the system performance. The design of channel coding must take channel characteristic, modulation and demodulation, equalization, channel estimation, diversity reception and multiuser detection into consideration. This method of design combining channel coding and other communication technologies has been fashionable in the field of wireless communication research.Turbo product codes (TPCs) are efficient error correcting codes. The performance of turbo product codes is better than that of turbo codes in high rate condition in additive Gaussian white noise channel. The asymptotic performance of turbo product code takes advantages over that of turbo code in high signal-noise ratio. This dissertation presents the study on the TPCs with its applications in wireless communication systems. The following items give the summarization of the main work:1. The Turbo Product Coded Pilot Symbol Assisted Modulation (TPC-PSAM) which joints channel estimation and decoding method in flat Rayleigh-fading channel is proposed. By applying the PSAM to estimate the channel state information, the proposed method can be used to realize the decoding of TPC in flat Rayleigh-fading channels. The equal gain combining can improve the performance of TPC-PSAM.2. When the TPCs are used for flat Rayleigh-fading channels, the system performance would be worse by zero-forcing equalization. To reduce the effect of the zero-forcing equalization on the iterative decoder, the new method of bit metric clipping is used to improve the performance of the TPCs, which is shown that the performance of the TPCs can be improved by 5 to 8dB.3. The method and performance of concatenated the TPCs and space-time block codes in flat Rayleigh-fading channels are given. The concatenated the TPCs and space-time block codes can reduce the error floor of space-time block codes in severely time-variant channels. This concatenated system can be used to improve the performance of space-time block codes with high bandwidth utilization.4. Differential detected turbo product coded modulation and diversity receptions of the TPC-MDPSK in correlated Rayleigh-fading channels are studied. The differential detection and diversity reception can be realized without any channel state information in TPC-MDPSK signals. The performance is better and the error floor is lower in the differential detected turbo product coded modulation compared with the differentialdetected trellis coded modulation. The performance of TPC-MDPSK with diversity reception in the correlated channels with correlated coefficient of 0.5 is only ldB worse than that in the independent fading channels.5. The least square channel estimation with low complexity in Turbo Product Coded Orthogonal Frequency Division Multiplexing (TPC-OFDM) over frequency-selective fading channels is presented. By using the diversity reception, the error floor in seriously frequency-selective fading channels is reduced. The gap between of TPC-OFDM under channel estimation and that under perfect channel state information with diversity reception is about 4dB worse in channel model recommended by EEEE802.16.6. Two design methods of wideband high-frequency (HF) modem based on TPC-OFDM with information rate of 8KB/s, 16KB/s and 32KB/s are presented over frequency-selective HF channels. The first method is based on coherent detection of TPC-OFDM using channel estimation, and the second method is based on differential detection of TPC-OFDM. The in-band frequency diversity is used to overcome the effect caused by the frequency-selective fading in system designs. Assuming the serious co-channel interference is obliterated, two design methods of modem in typical HF channel can work smoothly. The performance of the HF modem based on differential detected TPC-OFDM is more robust than that based on coherent detected TPC-OFDM.7. The effect of in-band residual interference on the performance of HF modem...