Abstract
Abstract With the rapidly increasing demand for high-speed data transmission and a growing number of terminals, massive multiple-input multiple-output (MIMO) has been shown promising to meet the challenges owing to its high spectrum efficiency. Although massive MIMO can efficiently improve the system performance, usage of orthogonal pilots and growing terminals causes large resource consumption especially when the coherence interval is short. This paper proposes a semi-orthogonal pilot design with simultaneous data and pilot transmission. In the proposed technique, we exploit the asymptotic channel orthogonality in massive MIMO systems, with which a successive interference cancellation (SIC)-based channel estimation is applied to mitigate the mutual interference between data and pilot. We derived the theoretical expressions of the achievable rates in massive MIMO systems with our proposed pilot design. Further discussion on performance verifies the superiority of our proposed pilot design for high or low signal-to-noise-ratios (SNRs) with any coherence interval length. And simulation results show that the proposed pilot design can achieve a significant performance improvement with reduced pilot resource consumption compared with the conventional orthogonal pilots.
Highlights
1 Introduction With a rapidly increasing demand for high data rates, as well as the growing number of serving users, massive multiple-input multiple-output (MIMO) is emerging as a promising technology to meet the challenge by providing a significant increment in reliability and data rate for wireless communications [1,2,3]
Massive MIMO requires a large number of pilots if frequencydivision duplexing (FDD) is used since the burden for downlink pilots is proportional to the number of base station (BS) antennas, while for time-division duplexing (TDD) [3,4], uplink training is an effective method to obtain channel state information (CSI) by exploiting channel reciprocity
In this work, we study the problem of an efficient pilot design by exploiting the asymptotic channel orthogonality [13] incorporated with successive interference cancellation (SIC) in massive MIMO systems
Summary
With a rapidly increasing demand for high data rates, as well as the growing number of serving users, massive multiple-input multiple-output (MIMO) is emerging as a promising technology to meet the challenge by providing a significant increment in reliability and data rate for wireless communications [1,2,3]. In this work, we study the problem of an efficient pilot design by exploiting the asymptotic channel orthogonality [13] incorporated with successive interference cancellation (SIC) in massive MIMO systems. We allow simultaneous data and pilot transmission and insert shifted pilot locations in slots, i.e., different users transmit pilots in different slots It takes advantage of the asymptotic channel orthogonality for massive MIMO. The conventional pilot design in massive MIMO systems utilizing orthogonal pilots can prevent pilot contamination within one cell and obtain relatively accurate channel estimates [2]. We will propose a possible pilot design which can keep a balance between the efficiency of data transmission and performance of the system
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