Improved Spatial Modulation for High Spectral Efficiency

Spatial Modulation (SM) is a technique that can enhance the capacity of MIMO schemes by exploiting the index of transmit antenna to convey information bits. In this paper, we describe this technique, and present a new MIMO transmission scheme that combines SM and spatial multiplexing. In the basic form of SM, only one out of MT available antennas is selected for transmission in any given symbol interval. We propose to use more than one antenna to transmit several symbols simultaneously. This would increase the spectral efficiency. At the receiver, an optimal detector is employed to jointly estimate the transmitted symbols as well as the index of the active transmit antennas. In this paper we evaluate the performance of this scheme in an uncorrelated Rayleigh fading channel. The simulations results show that the proposed scheme outperforms the optimal SM and V-BLAST (Vertical Bell Laboratories Layered space-time at high signal-to-noise ratio (SNR). For example, if we seek a spectral efficiency of 8 bits/s/Hz at bit error rate (BER) of 10^-5, the proposed scheme provides 5dB and 7dB improvements over SM and V-BLAST, respectively.Comment: 7 pages, 4 figures, 1 table, International Journal of Distributed and Parallel Systems (IJDPS) Vol.3, No.2, March 201

A novel spatial modulation using MIMO spatial multiplexing

In this paper we propose a new Multiple-Input Multiple-Output (MIMO) transmission scheme that combines the generalised spatial modulation (GSM) with MIMO spatial multiplexing technique. Unlike the GSM which uses NA active antennas to transmit the same symbol, the proposed scheme uses the N A antennas to transmit different symbols simultaneously, which leads to increase the spectral efficiency of the system. An optimal detector is used at the receiver to jointly estimate the transmitted symbols as well as the index of active antennas combination. However, the optimal detector suffers from a high computational complexity. To solve this problem we propose a suboptimal detector which is based on a zero forcing detector. The performance of the proposed scheme is evaluated in an uncorrelated flat fading channel and compared with the optimal spatial modulation and vertical Bell Labs layered space-time

Centralized decision feedback adaptive combined space-time detector for CDMA systems

An adaptive combined array and multiuser detector (spatial and temporal) structure for direct sequence code division multiple access (DS-CDMA) has been proposed in Legnain et al. (1998) to combat co-channel interference and increase the capacity for cellular CDMA. The structure uses a L-sensor (element) linear array. Each element is followed by a chip matched filter (CMF) and a fractionally spaced adaptive equalizer. The proposed structure outperforms the conventional receiver and the structures proposed in Abdulrahman et al. (1994) and Miller (1995) in-terms of capacity and near far resistance. In this paper we propose a new centralized decision feedback space-time receiver, which feeds back the detected symbols for all users through a FIR filter without respreading the detected symbols. The focus in this paper is the co-channel interference rejection capability of this structure. Analysis of the optimum tap weights and the minimum mean square error in multipath (no fading) channels are provided, and comparison between this structure and other structures are also provided

Effect of time-varying user population on the performance of the adaptive combined space-time receiver for DS-CDMA systems

An adaptive combined space-time detector for DS-CDMA system has been proposed by Legnain, Falconer and Sheikh (see IEEE GLOBECOM 98, Sydney, Australia, 1998) to combat cochannel interference and enhance the capacity of the adaptive MMSE multiuser detection. In this paper we study the effect of time varying user population (sudden death and birth) on the performance of the adaptive space-time multiuser detector proposed by Legnain et al. in frequency selective fading channels. Sudden birth of interferers degrades the performance of the adaptive MMSE detector, and the receiver needs to be readapted each time new interferers appear. We show that the adaptive space-time techniques alleviate the effect of sudden birth of interferers and there is no need to retrain the detector each time a new interferer appears or disappears