多輸入多輸出-正交分頻多工系統堆疊循環延遲天線分集技術之效能分析

Abstract

Current demand for wireless data services is growing exponentially. The wireless channel brings an unnumbered of limitations and constraints and has proved to be very expensive in some scenarios where spectrum licences can worth billions of dollars. Therefore, telecom providers around the globe are pushing the research community to come out with new technologies that can have a more efficient use of that appreciated resource. This work goes in that direction of how to affront the dilemma of achieving higher capacity systems without affecting the reliability of the link. First, we investigate a space-time code called stacked cyclic delay diversity (SCDD). Analysis of the different selection of parameters and construction of the space-time code is realized in a MIMO-OFDM channel. We discuss the diversity-multiplexing tradeoff analysis of the code and compare it with other schemes. Design and development of the MMSE linear receiver to separate the different streams is presented and performance results show that SCDD can be a promising technology. We investigate antenna configurations of 4Tx-2Rx and 4Tx-4Tx in a flat-fading channel and frequency-selective channel. The scheme shows that diversity gains can be doubled in a flat-fading channel when applying cyclic delay on the different antennas. In frequency-selective channels, gains are lower because the channel already provides some frequency-diversity to the system. Second, we develop a new scheme called stacked hybrid cyclic delay diversity (SHCDD). The purpose of this scheme is to close the gap even further between capacity and reliability in a system compared with SCDD. SHCDD can achieve non-integer rates, condition that it is not possible with SCDD. Parameter selection shows to follow similar rules than SCDD due to its similar structures. Comparison with the more widely known scheme, double space-time transmit diversity (DSTTD), is realized and shows that SHCDD can outperform DSTTD even in higher rates condition.

Current demand for wireless data services is growing exponentially. The wireless channel brings an unnumbered of limitations and constraints and has proved to be very expensive in some scenarios where spectrum licences can worth billions of dollars. Therefore, telecom providers around the globe are pushing the research community to come out with new technologies that can have a more efficient use of that appreciated resource. This work goes in that direction of how to affront the dilemma of achieving higher capacity systems without affecting the reliability of the link. First, we investigate a space-time code called stacked cyclic delay diversity (SCDD). Analysis of the different selection of parameters and construction of the space-time code is realized in a MIMO-OFDM channel. We discuss the diversity-multiplexing tradeoff analysis of the code and compare it with other schemes. Design and development of the MMSE linear receiver to separate the different streams is presented and performance results show that SCDD can be a promising technology. We investigate antenna configurations of 4Tx-2Rx and 4Tx-4Tx in a flat-fading channel and frequency-selective channel. The scheme shows that diversity gains can be doubled in a flat-fading channel when applying cyclic delay on the different antennas. In frequency-selective channels, gains are lower because the channel already provides some frequency-diversity to the system. Second, we develop a new scheme called stacked hybrid cyclic delay diversity (SHCDD). The purpose of this scheme is to close the gap even further between capacity and reliability in a system compared with SCDD. SHCDD can achieve non-integer rates, condition that it is not possible with SCDD. Parameter selection shows to follow similar rules than SCDD due to its similar structures. Comparison with the more widely known scheme, double space-time transmit diversity (DSTTD), is realized and shows that SHCDD can outperform DSTTD even in higher rates condition.