Supervised Learning Classifier Based Transmit Antenna Selection for SM-MIMO System

The average bit error rate (ABER) performance of low-density parity-check (LDPC)-coded orthogonal frequency-division multiplexing (OFDM) free-space optical communication system with K-ary quadrature amplitude modulation (QAM) and phase shift keying (PSK) modulation schemes is investigated over the composite Málaga fading channel with atmospheric attenuation and pointing errors considered. The probability density function and cumulative distribution function regarding the aggregated channel model are derived with the help of the generalized Gauss-Laguerre quadrature rule, the analytical ABER expressions for both QAM and PSK OFDM systems are then obtained. On the basis of them, the ABER performance is analyzed with different turbulence strengths, weather conditions, normalized beam width, normalized jitter, and specifically, different values of Málaga distribution parameter ρ. Monte Carlo simulation is offered to confirm the correctness of the proposed ABER models. Moreover, LDPC codes are added into the simulation to enhance system performance. The result shows that, for the same turbulence, weather, and pointing error conditions, whether the LDPC codes are taken into account or not, the ABER performance of 16-QAM OFDM system is better than that of 16-PSK OFDM system over the Málaga fading channel, and the ABER result decreases with higher ρ for both modulation schemes. Furthermore, the LDPC coding can significantly improve the system performance over this aggregated fading channel for these two modulation schemes, and a lower LDPC code rate can obtain a better ABER performance. This work is beneficial for free-space optical system design.

In this paper, the effective capacity of a multiple-input multiple-output (MIMO) system in two different cases with receive antenna selection (RAS) and transmit antenna selection (TAS) schemes is investigated. A closed-form solution for the maximum constant arrival rate of this network with statistical delay quality of service (QoS) constraint is extracted in the quasi-static fading channel. This study is conducted in two different cases. When channel state information (CSI) is not available at the MIMO transmitter, implementation of TAS is difficult. Therefore, RAS scheme is employed and one antenna with the maximum instantaneous signal to noise ratio is chosen at the receiver. On the other hand, when CSI is available at the transmitter, TAS scheme is executed. In this case, one antenna is selected at the transmitter. Moreover, an optimal power-control policy is applied to the selected antenna and the effective capacity of the MIMO system is derived. Finally, this optimal power adaptation and the effective capacity are investigated in two asymptotic cases with the loose and strict QoS requirements. In particular, we show that in the TAS scheme with the loose QoS restriction, the effective capacity converges to the ergodic capacity. Then, an exact closed-form solution is obtained for the ergodic capacity of the channel here.

Permutation index-quadrature spatial modulation: A spectral efficient spatial modulation for next generation networks

In this paper, a secure spatial modulation system with artificial noise-aided is investigated. To achieve higher secrecy rate (SR) in such a system, two high-performance schemes of transmit antenna selection (TAS), leakage-based and maximum secrecy rate (Max-SR), are proposed and a generalized Euclidean distance-optimized antenna selection (EDAS) method is designed. From simulation results and analysis, the four TAS schemes have a decreasing order: Max-SR, leakage-based, generalized EDAS, and random (conventional), in terms of SR performance. However, the proposed Max-SR method requires the exhaustive search to achieve the optimal SR performance, thus its complexity is extremely high as the number of antennas tends to medium and large scale. The proposed leakage-based method approaches the Max-SR method with much lower complexity. Thus, it achieves a good balance between complexity and SR performance. In terms of bit error rate, their performances are in an increasing order: random, leakage-based, Max-SR, and generalized EDAS.

Euclidean distance optimized antenna selection (EDAS) has proven to be able to achieve high transmit diversity gains for spatial modulation (SM) multiple-input multiple-output (MIMO) systems, but the exhaustive search over all possible antenna subsets may result in an intractable search complexity, especially for large-scale MIMO (LS-MIMO) systems. In this paper, a novel EDAS-equivalent criterion, relaying on matrix dimension reduction, is proposed to reduce the search complexity. Based upon this criterion, for small-scale SM-MIMO systems, a pair of transmit antenna selection (TAS) schemes, namely, the tree search based antenna selection (TSAS), and the decremental antenna selection (D-AS) schemes, are developed. Specifically, the TSAS scheme works by iteratively splitting the original Euclidean distance (ED) matrix into submatrices with smaller dimensions. TSAS achieves the same bit error rate (BER) performance as that of the exhaustive search at the cost of exponential search complexity. To address this issue, D-AS is carried out by excluding one specific transmit antenna from all the possible candidates in each iteration based on the channel information. D-AS is able to offer a near-optimal BER performance with a further reduction in terms of the search complexity. Moreover, we extend the D-AS scheme to LS-SM-MIMO systems by sorting all the ED elements with the low-complexity heapsort algorithm. Our simulation results show that the proposed D-AS algorithm outperforms conventional TAS schemes conceived for LS-SM-MIMO systems.

In this paper, the bit error rate (BER) performance of multiuser multiple-input multiple-output (MIMO) systems over Rayleigh fading channels is studied, and corresponding asymptotic performance is analyzed. Based on the asymptotic analysis at high signal to noise ratio (SNR), using the probability density functions (PDF) of the instantaneous channel power gain, the diversity gain and coding gain of the system with transmit antenna selection (TAS) scheme and space-time block coding (STBC) scheme are derived, respectively. As a result, the same full diversity gain is achieved for two transmission schemes, but their coding gains are different. With the obtained diversity gain and coding gain, the asymptotic BER expressions for two transmission schemes are respectively derived, which are in good agreement with the corresponding simulation results. The results show that the multiuser MIMO system with TAS scheme has better BER performance than that with STBC scheme due to higher coding gain.

We analyze the asymptotic performance of rate adaptation for Transmit Antenna Selection (TAS) and Maximum Eigenmode Beamforming (MEB) schemes in Multiple-Input Multiple-Output (MIMO) systems under imperfect channel state information (CSI) and feedback delay. The rate is adapted according to a target outage probability. We derive lower and upper bounds to this rate. We also asymptotically characterize the multi-step prediction error when MMSE prediction is used to combat feedback delay. Using the bounds and the prediction error asymptotics, we show that the rate gap from the ideal CSI scenario asymptotically grows logarithmically with SNR. The slope is at most the target outage probability. We find that when the target outage probability is decreased faster than an identified growth rate and prediction error goes to zero, then the rate gap remains bounded.

In this letter, we employ a machine learning algorithm based on transmit antenna selection (TAS) for adaptive enhanced spatial modulation (AESM). Firstly, channel state information (CSI) is used to predict the TAS problem in AESM. In addition, a low-complexity multi-class supervised learning classifier of deep neural network (DNN) is introduced. Meanwhile, adaptive gradient (AdaGrad) is applied to optimize the network structure and reduce network training time. Finally, the simulation results show that the proposed scheme efficiency is higher than traditional TAS in the AESM system and provides a similar bit error rate (BER) performance while the computational complexity of the system is lowest.

The Transmit antenna selection (TAS) technique is essential to increase the efficiency of spatial modulation (SM) systems. This TAS is an effective technique for reducing the Multiple Input Multiple Output (MIMO) systems, which can increase the computational difficulty and Bit error rate (BER) by various TAS algorithms. But these selection methods cannot provide code gain, so it is essential to join the external code in TAS to obtain code gain advantages in BER. In some existing work, the improved BER has been perceived by joining Forward Error Correction Code (FEC) and Space Time Block Code (STBC) for MIMO systems provided greater code gain. A multiple TAS-OSTBC technique with new integration of Bose–Chaudhuri–Hocquenghem (BCH)-Turbo code (TC) is proposed in this paper. The TAS-OSTBC system connects with the external BCH code in sequence of internal Turbo code. This combination can provide increasing code gain and the effective advantages of the TAS-OSTBC system. To perform the system analysis Rayleigh channel is utilized. In the case with multiple TAS-OSTBC systems, better performance can provide by this new combination of the BCH-Turbo compared to the conventional Turbo code for the Rayleigh fading.

This paper studies the performance of transmit antenna selection algorithms in spatially correlated fading MIMO channels. The antenna subset is selected based on maximizing the channel capacity. A novel method is proposed to select the optimum set of transmit antennas based on the upper bound on the mean channel capacity. The proposed method based only on the fading correlation and not the instantaneous channel realization. And also its computational complexity is low and tends to be realized. The simulation results show that antenna selection of transmitter can increase the channel capacity of MIMO system by 1 bit/s in a flat fading environment with a rank deficient channel.

ABSTRACTMultiuser diversity (MUD) can be exploited in multiuser networks to improve performance. In this paper, the outage probability (OP) of amplify-and-forward relaying multiuser networks with transmit antenna selection (TAS) over N-Nakagami fading channels is investigated. Exact closed-form OP expressions are derived for two TAS schemes. These expressions are used to evaluate the effect of the power allocation on the OP. Monte Carlo simulation is used to verify the analysis. The results show that MUD has a significant effect on the OP.

Performance analysis and comparison of a novel Steiner-Quadrature Space Shift Keying (S-QSSK) scheme in massive MIMO systems

In recent years, the THz frequency band (0.3 THz–10 THz) has attracted an increasing research interest for the realization of emerging high-speed wireless communication links. Nevertheless, the propagation of THz signals through the atmospheric channel is primarily subjected to signal attenuation due to free space path loss (FSPL), water vapor, adverse weather conditions along with atmospheric turbulence-induced and misalignment-induced scintillations. Therefore, in this work, a multi-hop line-of-sight THz system that utilizes serially connected decode-and-forward relays is proposed to extend the total THz coverage distance under the presence of fog, rain or clear weather conditions, as well as water vapor, atmospheric turbulence, non-zero boresight pointing errors and FSPL. Under these circumstances, an average bit error rate (ABER) analysis is performed. In this context, novel closed-form ABER expressions are derived. Their analytical results demonstrate the influence of each of the above limiting factors as well as their joint impact on the ABER performance. Finally, the feasibility of extending the total THz link distance through multi-hop relaying configurations is also evaluated.

In this paper, transmit antenna selection (TAS) is applied to space shift keying (SSK) modulation to obtain diversity gain. The receiver selects a transmit antenna subset in each transmission block according to the channel state information (CSI) and sends the subset index to the transmitter through feedback. Several antenna selection schemes are evaluated for SSK from perspectives of performance, feedback overhead and complexity. A greedy transmit antenna selection scheme is proposed to reduce the computation complexity, which shows almost the same performance as exhaustive search. In the special case that the number of active antennas equals two, an antenna selection scheme with one transmit antenna fixed (Fix-1 scheme) is proposed to reduce the amount of feedback, whose exact bit error ratio (BER) performance is derived. Through asymptotic BER analysis we show that Fix-1 scheme has the same diversity order as exhaustive search.

Recently massive MIMO systems have attracted a lot of attention. A serious limitation in implementing massive MIMO is the number of RF chains required, which is due to its high implementation cost and power consumption. Antenna selection is a wise remedy, that not only reduces the number of required RF chains, but also improves the system’s performance. In this work, two low complexity capacity-maximizing transmit antenna selection (TAS) schemes, one for low SNR region and one for medium to high SNR region, are proposed. It is shown that the proposed antenna selection schemes enhance the MIMO link’s capacity at low SNRs, and select only one antenna in more than $$90\%$$ of channel realizations, which in terms of numbers of required RF chains is very promising. The performance of the proposed schemes are compared to an existing high performance greedy TAS technique in terms of average capacity and complexity. Finally, a close analytical approximation for average capacity of the proposed capacity-based subset selection scheme is presented.