Research On Key Technologies Of Spatial Modulation And Massive MIMO Transmission

Spatial modulation (SM) and space shift keying modulation (SSK) are new multiple-input multiple-output (MIMO) transmission schemes in wireless communications. Com-pared with traditional MIMO transmission schemes, SM and SSK have advantages of lower complexity, fewer requirements on radio frequency links (RF), etc. In Massive MIMO systems, a large number of antennas are equipped at the base station (BS). By utilizing the asymptotic orthogonality between the channels of each user, Massive MIMO can provide multi-user access through simple linear signal processing while avoiding the inter-user interference. In this thesis, we focus on the improvements and applications of SM, SSK and Massive MIMO transmission technologies.The transmitting and receiving antenna selections for SSK modulation is investigated firstly. An antenna selection scheme (Fix-1) reducing the feedback overhead as well as low computational complexity antenna selection schemes are proposed, for which the exact bit error rate (BER) and a closed expression for the BER upper bound are derived.A distributed generalized space shift keying (GSSK) transmission system with re-stricted transmit antennas is then proposed, where several distributed base stations (BS) constitute a GSSK transmission system. Because each BS is equipped with a single ra-dio frequency (RF) link, it can activate only one antenna at the same time. Since BSs have different geographical locations, the signal sent by each BS will experience different large scale fading, which can be utilized to improve the system performance. The symbol error rate (SER) is derived for the distributed GSSK, then a power allocation scheme is proposed based on the convex optimization to minimize the system SER.Further, we propose to apply the space shift keying modulation to the scenario of high speed railway (HSR) wireless communications, where the wireless channel is modeled as a Lognormal-Rician composite fading channel. The SER performance of SSK is analyzed in this fading channel, and the effect of different antenna deployments on the SER are compared according to the characteristic of channels in HSR communications. Based on the performance analysis, a SSK transmission scheme combined with coordinated multiple point transmission (CoMP) is proposed. The proposed scheme can improve the system performance by utilizing the low correlation between shadowing fading, while avoiding the transmission power loss due to distributed antennas.A subspace projection based multiuser detection algorithm is proposed for the multi-ple access spatial modulation. On this basis, a SAGE aided subspace projection detection algorithm (S-LP) is proposed by combining with a modified expectation maximizing al-gorithm. The performance of the proposed algorithm can approach that of the maximum likelihood (ML) receiver and the sphere decoding (SD) receiver, while effectively reduce the computational complexity in a large scale system.Finally, a multiuser transmission structure is proposed based on the time division du-plex (TDD), orthogonal frequency division multiplexing (OFDM) and the massive MIMO, where each user occupies the whole bandwidth and the overhead for user scheduling is reduced. The system capacity is derived with the maximum likelihood channel estima-tion (MLE) and the minimum mean square error (MMSE) channel estimation. The the optimal number of users and the optimal length of pilot are derived, and the effect of the channel time selectivity and frequency selectivity on the system capacity is analyzed. Meanwhile, a power allocation scheme is proposed to improve the system capacity by utilizing the difference between the multi-path delay of each user.