Multiple-input-multiple-output (MIMO) wireless systems are those that have multiple antenna elements at both the transmitter and receiver. They were first investigated by computer simulations in the 1980s. Since that time, interest in MIMO systems has exploded. They are now being used for third-generation cellular systems (W-CDMA) and are discussed for future high-performance modes of the highly successful IEEE 802.11 standard for wireless local area networks. MIMO-related topics also occupy a considerable part of today's academic communications research. The multiple antennas in MIMO systems can be exploited in two different ways. One is the creation of a highly effective antenna diversity system; the other is the use of the multiple antennas for the transmission of several parallel data streams to increase the capacity of the system. This article presented an overview of MIMO systems with antenna selection. The transmitter, the receiver, or both use only the signals from a subset of the available antennas. This allows considerable reductions in the hardware expense.

MIMO systems with antenna selection

In this paper, we investigate a multiple-input-multiple-output (MIMO) scheme combining transmit antenna selection and receiver maximal-ratio combining (the TAS/MRC scheme). In this scheme, a single transmit antenna, which maximizes the total received signal power at the receiver, is selected for uncoded transmission. The closed-form outage probability of the system with transmit antenna selection is presented. The bit error rate (BER) of the TAS/MRC scheme is derived for binary phase-shift keying (BPSK) in flat Rayleigh fading channels. The BER analysis demonstrates that the TAS/MRC scheme can achieve a full diversity order at high signal-to-noise ratios (SNRs), as if all the transmit antennas were used. The average SNR gain of the TAS/MRC is quantified and compared with those of uncoded receiver MRC and space-time block codes (STBCs). The analytical results are verified by simulation. It is shown that the TAS/MRC scheme outperforms some more complex space-time codes of the same spectral efficiency. The cost of the improved performance is a low-rate feedback channel. We also show that channel estimation errors based on pilot symbols have no impact on the diversity order over quasi-static fading channels.

Analysis of transmit antenna selection/maximal-ratio combining in Rayleigh fading channels

We consider multiple-input - multiple-output (MIMO) systems with reduced complexity. Either one, or both, link ends chose the "best" L out of N available antennas. This implies that only L instead of N transceiver chains have to be built, and also the signal processing can be simplified. We show that in ideal channels, full diversity can be achieved, and also the number of independent data streams for spatial multiplexing can be maintained if certain conditions on L are fulfilled. We then discuss the impact of system nonidealities, like noisy channel estimation, correlations of the received signals, etc.

MIMO systems with antenna selection - an overview

The bit error rate of the Alamouti scheme with transmit antenna selection in flat Rayleigh fading channels is presented. Performance analysis reveals that this scheme achieves a full diversity order, as if all the transmit antennas were used. This scheme has a fixed low decoding complexity and provides a systematic method to construct full-rate space-time block codes with a full diversity order.

Performance of Alamouti scheme with transmit antenna selection

The pairwise-error probability upper bounds of space-time codes (STCs) in independent Rician fading channels are derived. Based on the performance analysis, novel code design criteria for slow and fast Rayleigh fading channels are developed. It is found that, in fading channels, the STC design criteria depend on the value of the possible diversity gain of the system. In slow fading channels, when the diversity gain is smaller than four, the code error performance is dominated by the minimum rank and the minimum determinant of the codeword distance matrix. However, when the diversity gain is larger than, or equal to, four, the performance is dominated by the minimum squared Euclidean distance. Based on the proposed design criteria, new codes are designed and evaluated by simulation.

Performance and design of space-time coding in fading channels

It has been established that the appropriate design parameters for space-time trellis code (STTC) in quasi-static flat Rayleigh fading channels are the rank and determinant criteria or the Euclidean distance criterion, depending on the value of the overall diversity gain. We propose two groups of new STTCs with more than two transmit antennas based on these two design criteria, respectively. These new STTCs are shown to achieve large performance improvements over the ones with two transmit antennas.

Space-time trellis codes for 4-PSK with three and four transmit antennas in quasi-static flat fading channels

It has been established that the appropriate design parameters for space-time trellis code (STTC) in quasi-static flat Rayleigh fading channels are the rank and determinant criteria or the Euclidean distance criterion, depending on the value of the overall diversity gain. We propose two groups of new 4- and 8-PSK STTCs with two to four transmit antennas based on these two design criteria, respectively. Simulation results show that increasing the number of transmit antennas in general provide large performance improvement.

Space-time trellis codes with two, three and four transmit antennas in quasi-static flat fading channels

Good 8-PSK space-time trellis codes (STTCs) for two, three and four transmit antennas are reported and the performance is evaluated by simulation The new STTCs with three and four transmit antennas achieve large performance improvements over those with two transmit antennas

Space-time trellis codes for 8-PSK with two, three and four transmit antennas in quasi-static flat fading channels

In this paper, we investigate a scheme for combining transmit-antenna selection (TAS) and maximal-ratio combining (MRC) (TAS/MRC). In this scheme a single antenna is chosen for transmission among all available transmit antennas and MRC is performed at the receiver side. The bit error rate (BER) of the TAS/MRC scheme is derived for binary phase-shift-keying (BPSK) in flat Rayleigh fading channels. The analysis shows that the TAS/MRC scheme can achieve the full diversity as if all the transmit antennas were used. The simulation shows that this scheme significantly outperforms the space-time block codes (STBCs) of the same diversity order with the same spectral efficiency.

Analysis of transmit antenna selection/ maximal-ratio combining in Rayleigh fading channels

An analytical bit error rate (BER) expression for a transmit antenna selection scheme with maximal-ratio combining at the receiver (TAS/MRC) is derived. The expression shows that this system asymptotically achieves a full diversity order.

Ka Leong Lo

Papers

Space-time trellis codes for 4-PSK with three and four transmit antennas in quasi-static flat fading channels

Space-time trellis codes with two, three and four transmit antennas in quasi-static flat fading channels

Space-time trellis codes for 8-PSK with two, three and four transmit antennas in quasi-static flat fading channels

Analysis of transmit antenna selection/ maximal-ratio combining in Rayleigh fading channels

Analysis of transmit antenna selection/maximal-ratio combining in Rayleigh fading channels