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Research on Transmission and Detection Technology for TDR-IDMA Signal

Author: XiongXingZhong
Tutor: HuJianHao
School: University of Electronic Science and Technology
Course: Communication and Information System
Keywords: Code Division Multiple Access Interleaving multiple access Time reversal Preprocessor Precoder Channel estimation Maximum expected Hybrid multiple access Multiuser Detection
CLC: TN929.53
Type: PhD thesis
Year: 2009
Downloads: 105
Quote: 3
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Abstract


Multiple access technology has been a personal communication fields, especially in cellular-based wireless mobile communication system architecture in one of the key technologies. Theoretical analysis and practical experience have proven segmentation based on non-orthogonal frequency division multiple access resources (CDMA) can be obtained when the ratio of orthogonal frequency division resources, time division multiple access (TDMA) and frequency division multiple access (FDMA) more high spectral efficiency, therefore CDMA technology has become the third generation mobile communication systems (3G) core technology which has been widely used. However, the CDMA system due to multi-access interference (MAI) the presence and in practice not fully played out on the capacity of CDMA in potential advantages. With the expansion of the capacity of the CDMA system, MAI growing problem, affecting 3G and future mobile communication system capacity and spectrum utilization efficiency further improved. In order to lower complexity to solve the increasingly serious CDMA system multi-user interference (MUI) issues, Liping professor proposed interleave division multiple access (IDMA: Interleave-Division Multiple Access), referred to as interleaving multiple access. In the IDMA system, the interleaver is used as the only means to distinguish between users, for different users using different interleaving patterns. Interleaver output sequence unrelated approximation between adjacent chips, so that by-chip (CBC: Chip-by-Chip) iterative multiuser detection (MUD: Multi-User Detection) can be achieved, which is the key to IDMA . IDMA as an emerging wireless multiple access technique, due to its unique advantages, so that in the next generation mobile communication has broad application prospects, has become the fourth generation mobile communication (4G) one of the most popular candidate for standard, researchers and caused widespread concern at home and abroad. The present study shows that although iterative IDMA systems than the traditional multi-user detection algorithm CDMA system is simple, but the signal detection convergence speed is very slow. Iterative Detection and IDMA system directly affects the convergence rate of the system's data transmission speed, the future mobile communication system has a higher data transfer rate, how to further improve the IDMA system, the convergence speed of iterative detection has very important significance. In addition, the IDMA system, the interleaver is used as the only means to differentiate users, although the uplink and downlink have symmetrical characteristics of the uplink signal processing method is applied to the downlink, from the theoretically feasible , but in fact is not desirable, after all downlink client on complexity, security, economy and other aspects have high demands. Based on the above problems, the subject focuses on a time-division duplex (TDD: Time-Division Duplexing), and time reversal (TR: Time Reversal) of the IDMA system signal transmission and detection techniques, such a system will be referred to as time-division two- working time reversal IDMA, that TDR-IDMA. The main research work includes the following: 1. IDMA iterative multiuser detection for the convergence rate of growth slowed down with the number of users of the problem, this project proposes an effective TR of IDMA-based iterative multiuser detection algorithm. The algorithm obtained by time-division duplex uplink channel impulse response time reversal, the base station receiver using the channel impulse response of the time reversal of the received signal preprocessing. With time reversal processing and compression characteristics of different users when the channel impulse response and a weak correlation between the different paths between the same user weak correlation, after pretreatment, the IDMA initial iterative multiuser detection SINR ( SINR: Signal to Interference and Noise Ratio) is much higher than pretreatment IDMA without making time-reversed initial SINR. IDMA thereby speeding up the convergence of iterative multiuser detection rate, thereby effectively solve the IDMA iterative multi-user detection speed bottlenecks. (2) For IDMA downlink client receives a relatively high degree of device complexity issues, the subject is proposed based on time division duplex mode, and time reversal techniques IDMA downlink transmission and reception method simplified. This method is obtained by time division duplex channel impulse response, the base station transmitter using the channel impulse response of the transmission signal preprocessing time reversal. In time reversal and multi-input single-output (MISO: Multiple Input-Single Output) technology under the effect of using different user channel impulse response and a weak correlation between the time reversal processing spatial and temporal compression characteristics, weakening multi-user interference and co-channel interference (CCI) and inter-symbol interference (ISI). Allowing users receiving end with a simple single-path receiver to complete the signal detection, to avoid the complex chip by chip iterative multi-user detection, while the channel estimator is also transferred from the client to the base station side, thereby enabling the user end receiver device complexity is greatly simplified. Further, the subject is also proposed a IDMA / CDMA hybrid transmission mode to overcome IDMA client downlink receiving device is relatively high complexity problems. In this mixed mode, the uplink transmission and detection using IDMA downlink using IDMA / CDMA hybrid transmission and detection. In the downlink transmission and detection system in order to suppress or eliminate the MUI, on the one hand, the choice of the orthogonal code as the user better performance waveform code signal is detected at the receiving end user, the use of codes between users of the waveform correlation information processing a received signal; other hand, the original CDMA, each user uses the same interleaver to different users using different interleavers, and thus can enhance the single-user client signal is detected. 3 IDMA system for the single carrier frequency domain equalization (FDE: Frequency Domain Equalization) in the pre-coding complexity problems, the subject of proposed reversal precoding based on time and frequency domain equalization iteration LMMSE transmission detection algorithm that is a single-carrier TDR -IDMA system frequency domain equalization transfer detection algorithm, so that the transmitter precoding more simple and easy to implement. Finally, the single-carrier TDR-IDMA system time reversal precoding IDMA system with single-carrier injection principle of pre-coded, optimized precoding and Proakis B channel precoding without making criterion in the iterative LMMSE frequency domain equalization algorithm performance comparison and analysis. 4 Iterative Detection for IDMA system's strengths and maximum expected (EM: Expectation Maximization) algorithm characteristics, the subject was proposed based on the EM algorithm IDMA systems with mixed iterative channel estimation. Discussed the presence of channel estimation error signal when the detection algorithm and assessment methods, through the analysis of channel estimation error on IDMA system performance is proposed to overcome the channel estimation error on IDMA system performance impacts of response measures.

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Wireless communications > Mobile Communications > Cellular mobile communications systems (mobile phones, mobile phone handsets )
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