Transmit Antenna Selection With Maximal Ratio Combining Research Articles

Performance analysis of scheduled TAS‐MRC MIMO systems with multiple interferers

The authors present the performance analysis of a scheduled transmit antenna selection with maximal ratio combining (TAS-MRC) for multiple-input multiple-output transmission in the presence of multiple interferers. They derive the probability density function of the instantaneous post-processing signal to interference plus noise ratio for the scheduled TAS with MRC over the Rayleigh fading channels under multiple interferers. Using the distribution, the closed-form expressions of the scheduled TAS with MRC are derived for symbol error rate (SER), outage probability and ergodic capacity in the presence of multiple interferers. From the analysis results, the performance of the scheduled TAS-MRC in the presence of multiple interferers is mainly determined by the signal-to-interference ratio. The performance of SER and ergodic capacity is less sensitive to the number of interferers.

Secrecy performance analysis of TAS/MRC system in the presence of channel estimation error

This paper presents secure transmission in transmit antenna selection with maximal ratio combining (TAS/MRC) over Rayleigh fading channel for multiple input multiple output (MIMO) taking channel estimation error into account. In this paper, we evaluate the probability of non-zero secrecy capacity (PNZSC) and secrecy outage probability (SOP) for TAS/MRC system considering the impact of channel estimation error (CEE). The numerical results show that the system is valid for any transreceiving and eavesdropping antennas in general.

Outage Performance of Selective Dual-Hop MIMO Relaying with OSTBC and Transmit Antenna Selection in Rayleigh Fading Channels

For dual-hop multiple-input multiple-output (MIMO) decode-and-forward relaying systems, we propose a selective relaying scheme that uses orthogonal space-time block code (OSTBC) and transmit antenna selection with maximal-ratio combining (TAS/MRC) or vice versa at the first and second hops, respectively. The aim is to achieve an asymptotically identical performance to the dual-hop relaying system with only TAS/MRC, while requiring lower feedback overhead. In particular, we give the selection criteria based on the antenna configurations and the average channel powers for the first and second hops, assuming Rayleigh fading channels. Also, the numerical results are shown for the outage performance comparison between the dual-hop DF relaying systems with the proposed scheme, only TAS/MRC, and only OSTBC.

Transmit Antenna Selection in Cognitive MIMO Relaying With Multiple Primary Transceivers

The authors consider transmit antenna selection (TAS) in cognitive multiple-input–multiple-output (MIMO) relay networks as an interference-aware design for secondary users (SUs) to ensure power and interference constraints of multiple primary users (PUs). In doing so, the authors derive new exact and asymptotic expressions for the outage probability of TAS with maximal ratio combining (TAS/MRC) and with selection combining (TAS/SC) over Rayleigh fading. The proposed analysis and simulations highlight that TAS/MRC and TAS/SC with decode-and-forward relaying achieve the same diversity order in cognitive MIMO networks, which scales with the minimum number of antennas at the SUs. Furthermore, the authors accurately characterize the outage gap between TAS/MRC and TAS/SC relaying as a concise ratio of their array gains.

SER Analysis of Scheduled TAS With MRC in the Presence of Non-Identical Channel Estimation Errors

In this letter, we present a performance analysis of scheduled transmit antenna selection with maximal ratio combining (TAS-MRC) in the presence of non-identical channel estimation errors. This letter derives the probability density function (PDF) of the instantaneous effective signal-to-noise ratio for the scheduled TAS-MRC over Rayleigh fading channels with non-identical channel estimation errors. Using this PDF, we derive exact closed-form expressions for the scheduled TAS-MRC symbol error rate in the presence of non-identical channel estimation errors. The analysis results show that the order of diversity of scheduled TAS-MRC is improved in terms of transmit spatial diversity and multiuser diversity, whereas the received diversity is diminished by non-identical channel estimation errors, regardless of the modulation type.

Space-Time Network Coding With Transmit Antenna Selection and Maximal-Ratio Combining

In this paper, we investigate space-time network coding (STNC) in cooperative multiple-input multiple-output networks, where U users communicate with a common destination D with the aid of R decode-and-forward relays. The transmit antenna selection with maximal-ratio combining (TAS/MRC) is adopted in user-destination and relay-destination links where a single transmit antenna that maximizes the instantaneous received signal-to-noise ratio is selected and fed back to transmitter by receiver and all the receive antennas are combined with MRC. In the presence of perfect feedback, we derive new exact and asymptotic closed-form expressions for the outage probability (OP) and the symbol error rate (SER) of STNC with TAS/MRC in independent but not necessarily identically distributed Rayleigh fading channels. We demonstrate that STNC with TAS/MRC guarantees full diversity order. To quantify the impact of delayed feedback, we further derive new exact and asymptotic OP and SER expressions in closed form. We prove that the delayed feedback degrades the full diversity order to (R + 1)ND, where ND is the antenna number of the destination D. Numerical and Monte Carlo simulation results are provided to demonstrate the accuracy of our theoretical analysis and evaluate the impact of network parameters on the performance of STNC with TAS/MRC.

Analysis of TAS/MRC based MIMO Systems over η − µ Fading Channels

ABSTRACTIn this paper, we derive expressions for exact, approximate, and asymptotic symbol error rate (SER) of transmit antenna selection with maximal ratio combining (TAS/MRC) multiple input multiple output (MIMO) systems for several modulation schemes. We have assumed independent and identically distributed η − µ fading channels. We use a moment generating function (MGF) based approach to derive the expressions of SER. The expression for approximate SER is derived by approximating Q Function as a sum of exponentials. The expressions of SER are in the form of sum of converging infinite series for all values of fading parameters. The analytical expressions derived in this paper are also applicable to the SER performance analysis of TAS with selection combining at receiver (TAS/SC) systems. The analytical results are validated by comparing them with the results of extensive Monte Carlo simulations for different values of fading parameters. Finally, the SER performance of TAS/MRC systems and TAS/SC systems has been compared and superiority of TAS/MRC systems over TAS/SC systems has been demonstrated.

Cognitive MIMO Relaying Networks With Primary User's Interference and Outdated Channel State Information

In this paper, we propose transmit antenna selection with maximal ratio combining (TAS/MRC) in dual-hop decode-and-forward spectrum-sharing relaying networks with the primary user's interference and outdated channel state information (CSI). In this network, a single antenna that maximizes the received SNR is selected at the secondary transmitter, and the MRC is adopted at the secondary receiver. To efficiently evaluate the impact of key parameters on the system performance, we derive the exact analytical expression for the outage probability of the secondary network in a Rayleigh fading channel. Moreover, we present simple asymptotic expressions for the outage probability in a high SNR regime, which reveal practical insights on the achievable diversity order and coding gain. The findings suggest that whether the outdated CSI concerning the secondary transmission links has significant impact on the outage probability of the system depends on the interference power constraint at primary receivers. Specifically, under the proportional interference power constraint, the achievable diversity order is affected by imperfect CSI regarding the secondary transmission links, and the diversity–multiplexing tradeoff is independent of the primary network. However, under the fixed interference power constraint, the error floor is displayed, and the achievable diversity order reduces to zero regardless of the CSI concerning the secondary transmission links.

Performance analysis comparison of transmit antenna selection with maximal ratio combining and orthogonal space time block codes in equicorrelated Rayleigh fading multiple input multiple output channels

In this study, bit error rate (BER) performance of multiple input multiple output (MIMO) systems employing transmit antenna selection with maximal ratio combining (TAS/MRC) and orthogonal space time block codes (OSTBC) is analysed and compared. Analysis has been done for several modulation schemes in equicorrelated Rayleigh fading channels. Novel infinite series expressions for BER of TAS/MRC are proposed in this work. The authors observe that the existing literature on performance analysis of TAS/MRC in correlated channels implicitly or explicitly assume no correlation on the transmitter side. In this work the authors overcome this shortcoming. An alternate closed-form expression for BER performance of OSTBC MIMO systems is derived. This closed-form expression is computationally efficient than existing expressions. Monte Carlo simulations were performed to validate the analytical results. It has been observed that TAS/MRC outperforms OSTBC in terms of BER performance in equicorrelated Rayleigh fading channel. As a case study, performance comparison of cognitive radio (CR) links employing OSTBC and TAS/MRC MIMO systems is investigated in order to show the usefulness of the present analytical study. Even though TAS is the optimum transmit antenna technique in terms of BER performance, OSTBC seems to be a promising alternative for more realistic scenarios in CR systems.

Multiuser MIMO Relay Networks in Nakagami-m Fading Channels

This paper proposes a low complexity protocol that preserves full diversity in multiuser amplify-and-forward relay networks with NS antennas at the source, NR antennas at the relay, and ND antennas at each of the K destinations. In the proposed protocol, a two-fold diversity is guaranteed: 1) multi-antenna diversity via transmit antenna selection with maximal-ratio combining (TAS/MRC), and 2) multiuser diversity via opportunistic scheduling. Under perfect feedback with precise channel state information (CSI), we derive new exact and asymptotic symbol error rate (SER) expressions in closed-form for the general case of Nakagami-m fading. We prove that the full diversity order of NSNDKmX + min{NSNRmY, NRNDKmZ} is guaranteed, where mX, mY, and mZ denote the fading parameters of the source-destination, source-relay, and relay-destination links, respectively. To examine the impact of delayed feedback, we next derive new exact and asymptotic SER expressions in closed-form. We prove that in the presence of delayed feedback, outdated CSI degrades the diversity order to NDmX + min{NRmY, NDmZ}. In addition, based on our asymptotic expressions, we determine the optimal power allocation between the source and the relay such that the SER is minimized. We show that optimal power allocation offers superior performance over uniform power allocation; highlighting a pivotal design choice for maximizing network performance without investing additional resources.

Cascaded TAS/MRC in MIMO Multiuser Relay Networks

We propose cascaded transmit antenna selection with maximal-ratio combining (TAS/MRC) for use in multiuser relay networks (MRN) with NS, NR, and ND antennas at the source, the relay, and each of the K destinations, respectively. We consider opportunistic scheduling where the destination with the highest instantaneous end-to-end signal-to-noise ratio (SNR) is scheduled for transmission. In cascaded TAS/MRC, a single transmit antenna that maximizes the instantaneous received SNR in each hop is selected, and all the receive antennas are MRC combined. We derive new exact closed-form statistics of the end-to-end SNR, from which we derive the exact and the approximate symbol error rate (SER) for M-ary quadrature amplitude modulation (M-QAM) and M-ary phase-shift keying (M-PSK). New concise expressions are derived to characterize the diversity order and the array gain. We highlight that our proposed scheme attains the maximum diversity order of NR × min{NS, NDK}. Furthermore, we determine the optimal power assignment at the source and the relay that minimizes the SER.

Performance Analysis of Multiuser Diversity in MIMO Systems with Antenna Selection

In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent "virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems.