Single Transmit Antenna Selection Research Articles

Secrecy Throughput Optimization and Precoding Design in Adaptive Transmit Antenna Selection Systems With Limited Feedback

We analyze the secrecy performance of a wireless system with limited feedback, where the channel state information (CSI) is imperfectly known at a multi-antenna source. In order to mitigate the adverse effects of limited feedback and eavesdropper attack on secrecy transmission, we propose the quantized secrecy precoding (QSP) oriented adaptive transmit antenna selection (ATAS) scheme denoted as QSP-ATAS, where the transmit antennas with poor channel quality are inactivated by adjusting the channel gain threshold. Besides, the conventional single transmit antenna selection (STAS) scheme without secrecy precoding (NSP-STAS), where only the optimal transmit antenna has the chance to be selected for transmission, is considered as a baseline. Since that both the number of active transmit antennas and the number of quantization bits affect the quantization error, we define the effective secrecy throughput as the difference between the secrecy data rate and feedback rate to evaluate the system performance. We conduct an effective secrecy throughput analysis for both QSP-ATAS and NSP-STAS schemes and show the existence of the maximal effective secrecy throughput of proposed QSP-ATAS scheme. Furthermore, an optimization analysis of the QSP-ATAS scheme is carried out for the sake of further improving the effective secrecy throughput with regard to the channel gain threshold. Numerical simulation results demonstrate that our proposed QSP-ATAS scheme performs better than the conventional NSP-STAS scheme in terms of the effective secrecy throughput.

Error performance of QAM schemes for SIMO and MIMO networks

In this paper, we analyze the average symbol error rate (ASER) of single-input multiple-output (SIMO) networks for rectangular quadrature amplitude modulation (RQAM) and cross-QAM (XQAM) subject to Rayleigh fading. Then, we investigate the performance of RQAM for a SIMO system under κ-μ fading conditions. And also, we consider a multiple-input multiple-output with single transmit antenna selection and maximal ratio combining over Rayleigh fading environments. To analyze the key parameters on the network performances, we propose the analytical expressions of ASER for the considered networks. Assuming flat fading, the obtained exact and approximate expressions for ASER based on the probability density function approach. Furthermore, we present asymptotic expressions of RQAM and XQAM schemes for a SIMO system over Rayleigh fading at the high signal to noise ratio to evaluate the network performance in terms of diversity gain. Finally, simulations are ensured to confirm the correctness of our frameworks in this study.

Asymptotic capacity analysis under different adaptive transmission for TAS/MRC MIMO scheme subject to Weibull fading channels

This paper investigates a unified average channel capacity (ACC) analysis under different adaptive transmission of multiple-input multiple-output (MIMO) system, combining single transmit antenna selection (TAS) and maximal-ratio combining (MRC) receiver operating under independent flat Weibull multipath fading channels (WFCs). Based on a tight approximate probability density function expression of the signal-to-noise ratio (SNR) at the considered receiver output, we derive new accurate closed-form expressions of ACC for TAS/MRC system employing several rate adaptation techniques, namely optimal rate adaptation, optimal simultaneous power and rate adaptation, channel inversion with fixed rate (CIFR), truncated CIFR (TCIFR), and continuous power TCIFR (CTCIFR). Further, asymptotic expressions, in both high and low-SNR regimes, are investigated. The results show high accuracy for significant values of Lt×Lr TAS/MRC system. Indeed, the smaller Lt×Lr, the better the PDF’s accuracy, therefore, the better are the capacities. Numerical outcomes have been assessed by utilizing Mathematica and Matlab Software and corroborated via Monte-Carlo simulations.

QAM signaling over [formula omitted] shadowed fading channels

In this study, average symbol error rate (ASER) expressions for rectangular quadrature amplitude modulation (RQAM) and cross quadrature amplitude modulation (XQAM) over κ−μ shadowed fading are proposed by considering two different system models. In the first system model, a single-input–single-output (SISO) scheme is considered while a multiple-input–multiple-output (MIMO) with single transmit antenna selection and maximal ratio combining (TAS/MRC) is investigated as a second system model. First, the exact, approximate and asymptotic ASER expressions of RQAM and XQAM for a SISO system model are proposed based on probability density function (PDF) of instantaneous signal-to-noise ratio (SNR). Second, ASER expressions of RQAM and XQAM schemes for a MIMO system with TAS/MRC are obtained by using the PDF of instantaneous SNR at the receiver side. Then, ASER performances of RQAM and XQAM for the considered two system models are compared in the presence of different fading configurations. Finally, our numerical results illustrate that the analytical ASER expressions proposed in this study are well agreement with their simulations.

Analysis of Ergodic Rate for Transmit Antenna Selection in Low-Resolution ADC Systems

In this paper, we analyze the ergodic rate of single transmit antenna selection (TAS) in low-resolution analog-to-digital converter (ADC) systems. Using low-resolution ADCs is a potential power-reduction solution for multiple antenna systems. Low-resolution ADC systems with TAS can further reduce cost and power consumption in wireless transceivers. Considering such systems, we derive the approximated lower bound of the ergodic rate with TAS. Here, we exploit the approximated distribution of the sum of Weibull random variables to address the challenge involved in analyzing the quantization error. We, then, derive the approximated ergodic rate with TAS for a single receive antenna in closed form, which reveals the TAS gain in low-resolution ADC systems. The upper bound of a single transmit and single receive antenna system under coarse quantization is derived to compare with the ergodic rate of the TAS system. The analysis shows that the TAS method achieves a large improvement in ergodic rate with a moderate number of transmit antennas. Simulation results validate the derived ergodic rates and resulting intuition.

A Study of Single Transmit Antenna Selection with Modulation

Multiple-input multiple-output (MIMO) systems have attracted a vast amount of interest, due to improvements offered in capacity and diversity. However, several challenges still remain. Single transmit antenna selection with modulation (STASM) is an important closed-loop variant of MIMO, and addresses several of its challenges, while achieving full-diversity. On this note, the average symbol error probability (ASEP) of STASM with M-ary quadrature amplitude modulation (M-QAM) and M-ary phase shift keying (M-PSK) is formulated and validates the Monte Carlo simulation results. The formulated ASEP expressions are relatively easy to evaluate. Euclidean distance-based antenna selection for spatial modulation (EDAS-SM) is an innovative closed-loop MIMO scheme that provides many advantages. However, since STASM achieves a full-diversity compared to EDAS-SM, there exists a cross-over point after which its error performance is superior to the latter. For multiple receive antennas, the cross-over point only occurs in the moderate-to-high signal-to-noise ratio region, which may be difficult to achieve in practice. Hence, an adaptive transmit mode switching system based on STASM and EDAS-SM as transmission candidates is proposed. A selection criterion for the transmission candidate is based on minimizing the instantaneous symbol error probability in every transmission interval. By switching between STASM and EDAS-SM, the proposed scheme minimizes the ASEP.

Opportunistic Group Antenna Selection in Spatial Modulation Systems

This paper proposes an opportunistic spatial modulation (OSM) scheme where the transmit antennas are divided into $K\geq 1 $ equal groups, and the best antenna from each group is selected to form a $K$ transmit antenna subset for implementing spatial modulation (SM). Thus, the activation of one antenna from the subset to transmit one of the $M$ -ary modulation symbols achieves a data rate of $\log _{2} (K) +\log _{2} (M)$ bits per channel use. Notably, special cases of OSM include conventional SM and pure single transmit antenna selection. To characterize and comparatively evaluate OSM, we first consider phase-shift keying modulation and derive a closed-form, improved union-bound of symbol error probability (SEP) with a single-antenna receiver. Explicit expressions for the SEP in the high signal-to-noise ratio regime are also presented. Extensions to quadrature amplitude modulation analysis and simulations of multiple-antenna reception case are also provided. Simulation results corroborate the analytical results and reveal the interesting interplay between the signal and spatial constellation diagrams. For a given number of transmit antennas and targeted data rate, asymptotically, the SEP can be minimized by using only one antenna group and the largest size of signal constellation, as this configuration achieves the full-diversity order.

Transmit Antenna Selection with Optimum Combining for Aggregate Interference in Cognitive Underlay Radio Network

Transmit antenna selection (TAS) is most popular technique in underlay cognitive radio (CR) networks as they increase the capacity of secondary users with less hardware requirements. In this paper, a new scenario of CR ad-hoc network topology is proposed in which apart from primary users, there are multiple number of secondary users which are assumed to be distributed as homogeneous spatial Poisson point process (PPP) and are trying to use the primary spectrum in underlay mode. These multiple secondary transmitters generate the aggregate interference and can degrade the performance of secondary receiver. Here this aggregate interference is estimated and its impact on performance of secondary receiver under unconstrained mode of operation is presented. Further, to enhance the performance of secondary receivers in this scenario, single TAS technique based on maximizing the received signal to interference noise ratio by using optimum combining (OC) method is proposed. Furthermore, in this work the design of end to end Simulink based environment for secondary trans---receiver system with advancements in channel design and estimation is proposed. The bit error rate (BER) analysis is presented and verified for image data for single TAS-OC technique for unconstrained mode in underlay CR network in Rician fading channel. The BER performance is also presented for different number of secondary interference sources which are located at fixed distance in one case and they are assumed to be distributed as PPP in another case.

Feedback‐error‐resistant and reduced feedback‐rate orthogonal space‐time block coding scheme employing single transmit antenna selection

A novel and generic transmit diversity scheme that employs combined single transmit antenna selection (TAS)/orthogonal space-time block coding (OSTBC) scheme with reduced feedback-rate and robust error performance in the presence of feedback errors (FEs) is introduced in this paper. Statistical expressions and performance metrics related to the post-processing signal-to-noise ratio of the proposed scheme are derived for Nakagami-m fading channels considering that the channel estimation process is error-free and the feedback information is delivered to the transmitter side with no delay. Exact expressions for outage probability and bit/symbol error rates of M-ary signals are presented to examine the system performance in the presence of FEs extensively. Also, the asymptotic analysis is provided to explore the asymptotic diversity order and the asymptotic coding gain of the proposed scheme that is compared with that of the conventional TAS/OSTBC scheme from different perspectives. The proposed scheme is shown to provide not only full-diversity order as the conventional scheme for perfect feedback case but also superior error performance in the presence of FEs. Moreover, the error performances of both schemes and the superiority of the modified scheme are examined by considering an error-correcting structure in the feedback link.

Diversity Order and Coding Gain of General-Order Rectangular QAM in MIMO Relay With TAS/MRC in Nakagami- <inline-formula> <tex-math notation="TeX">$m$</tex-math></inline-formula> Fading

Recently, multiple-input-multiple-output (MIMO) relay networks have been an active area of research, particularly with combining single transmit antenna selection (TAS) and receiver maximal ratio combining (MRC). Moreover, general-order rectangular quadrature amplitude modulation (QAM) has received much attention for its high spectral efficiency and flexible modulation scheme. However, the analytical performance of general-order rectangular QAM has not been found in the literature for MIMO relay with TAS/MRC in Nakagami- m fading channels in spite of its practical usefulness. In addition, the analytical performance of general-order rectangular QAM often comes with enormous computational complexity. Therefore, it is hardly possible to understand the analytical solution unless the symbol error probability (SEP) is plotted graphically. In this paper, we present the SEP of general-order rectangular QAM in a MIMO relay with TAS/MRC using the sampling property of the delta impulse function. The SEP of MIMO relay networks is shown in terms of diversity order and coding gain. The proposed sampling method can also significantly reduce the computational complexity of the SEP of general-order rectangular QAM.

Outage Probability Analysis of MIMO Cognitive Radios with Single Transmit and Receive Antenna Selection

For multiple-input multiple-output cognitive radio systems, we propose an optimal single transmit and receive antenna selection scheme which maximizes the signal-to-interference-and-noise ratio. Considering peak interference power constraint, peak transmit power constraint, and interference from primary transmitter to cognitive receiver, we theoretically derive the exact system outage probability. It is shown that the theoretical results match simulation results.

Spectral occupancy rate of cognitive radio networks in queueing with adaptive modulation and coding over multiple‐input and multiple‐output transmit antenna selection/maximal ratio combining in Nakagami‐ m fading

Cognitive radio is successfully overlayed on the single user cross-layer design and implementation with adaptive modulation and coding (AMC) over frame-slotted transmission. The authors analyse the spectral occupancy rate of cognitive radio networks with AMC and queueing effect. They employ multiple-input and multiple-output with single transmit antenna selection and maximal ratio combining in Nakagami- m fading channel. The average spectral efficiency and packet dropping rate are also obtained. The analytical result shows that significant cognitive radio traffic can be accommodated without compromising the primary user network quality.

Transmit Antenna Selection with Alamouti Coding and Power Allocation in MIMO Wiretap Channels

In this work, we propose a new transmit antenna selection (TAS) scheme which examines the trade-off between feedback overhead and secrecy performance in multiple-input multiple-output wiretap channels. Our new scheme is carried out in two steps. First, the transmitter selects the first two strongest antennas to maximize the instantaneous signal-to-noise ratio (SNR) of the transmitter-receiver channel. Second, Alamouti coding is employed at the selected antennas in order to perform secure data transmission. When equal power is applied to the selected antennas, we refer to our new scheme as TAS-Alamouti. To provide valuable insights into TAS-Alamouti, we derive new closed-form expressions for the secrecy performance metrics. In terms of these metrics, we show how in a Rayleigh fading channel that our TAS-Alamouti scheme outperforms the traditional single TAS scheme conditioned on the SNR of the transmitter-receiver channel being larger than a specific value. We show how in some antenna configurations no additional feedback, relative to single TAS, is required in order to realize such performance enhancements. Furthermore, we show how optimal power allocation (OPA) across the selected antennas at the transmitter leads to a new scheme, which we refer to as TAS-Alamouti-OPA, that outperforms single TAS unconditionally. Relative to TAS-Alamouti, TAS-Alamouti-OPA requires only one additional feedback bit.

Transmit Antenna Selection Systems: A Performance Comparison of Different Types of Receiver Schemes

In this survey article, we compare the performance of single transmit antenna selection (TAS) systems with different kinds of receiver schemes. These systems include the TAS/switch-and-examine combining (TAS/SEC), TAS/SEC with postselection (TAS/SECPS), TAS/generalized selection combining (TAS/GSC), and TAS/output-threshold generalized selection combining (TAS/OT-GSC) systems. The performance comparisons are made in terms of the average output signal-to-noise ratio (SNR), symbol-error rate (SER), the number of channel estimates Ne, and the number of branches required for processing Np . It is shown that the TAS/SECPS and TAS/OT-GSC systems can achieve similar performance compared with the TAS/selection combining (SC) and TAS/GSC systems, respectively, with a reduced number of both channel estimates and branches required for processing when the predetermined SNR threshold is optimized.

Performance Analysis of Joint Single Transmit and Receive Antenna Selection in Nakagami-m Fading Channels

In this paper, multi-antenna systems employing both single transmit and single receive antenna selection (single TAS/single RAS) are examined for independent and identically distributed (i.i.d.) flat Nakagami-m fading channels. In this joint selection scheme, signal transmission and reception is performed over a single communication link with the highest signal-to-noise ratio (SNR). Exact bit/symbol error rate expressions for binary modulation, M-ary phase shift keying and square M-ary quadrature amplitude modulation signals are derived by using the moment generating function based analysis method. Also, upper bounds are obtained in order to show that the investigated systems achieve full diversity orders at high SNRs. Besides, outage probability analysis is carried out for examining system capacity. Analytical results are validated by simulations.

Error performance of maximal-ratio combining with transmit antenna selection in flat Nakagami-m fading channels

In this paper, the performance of an uncoded multiple-input-multiple-output (MIMO) scheme combining single transmit antenna selection and receiver maximal-ratio combining (the TAS/MRC scheme) is investigated for independent flat Nakagami-m fading channels with arbitrary real-valued m. The outage probability is first derived. Then the error rate expressions are attained from two different approaches. First, based on the observation of the instantaneous channel gain, the binary phase-shift keying (BPSK) asymptotic bit error rate (BER) expression is derived, and the exact BER expression is obtained as an infinite series, which converges for reasonably large signal-to-noise ratios (SNRs). Then the exact symbol error rate (SER) expressions are attained as a multiple infinite sum based on the moment generating function (MGF) method for M-ary phase-shift keying (M-PSK) and quadrature amplitude modulation (M-QAM). The asymptotic SER expressions reveal a diversity order equal to the product of the m parameter, the number of transmit antennas and the number of receive antennas. Theoretical analysis is verified by simulation.

Optimal Signaling and Selection Verification for Single Transmit-Antenna Selection

In marked contrast with the ideal error-free feedback assumption that is common in the literature, practical systems are likely to have severely bandwidth-limited, error-prone feedback channels. We consider the scenario where feedback from the receiver is used by the transmitter to select the best antenna, out of many available antennas, for data transmission. Feedback errors cause the transmitter to select an antenna different from the one signaled by the receiver. We show that optimizing the signaling assignment, which maps the antenna indices to the feedback codewords, improves performance without introducing any additional redundancy. For a system that uses error-prone feedback to transmit quadrature-phase-shift-keying-modulated data from a single antenna selected from many available spatially correlated antennas, we derive closed-form approximations for the data symbol error probability for an arbitrary number of receive antennas. We use these to systematically find the optimal signaling assignments using a low-complexity algorithm. The optimal signaling is intimately coupled to how the receiver performs selection verification, i.e., how it decodes the data signal when, due to feedback errors, it does not always know which antenna was used for data transmission. We show that ignoring feedback errors at the receiver can lead to an unacceptable performance degradation, and develop optimal and suboptimal, blind and nonblind selection-verification methods. With a small side-information overhead, nonblind verification approaches the ideal perfect selection-verification performance