BER Performance Analysis of Multiuser Diversity with Antenna Selection in MRC MIMO Systems

In this paper, we present a performance analysis of the user scheduling for the multiuser MIMO systems exploiting the multiuser and antenna diversities while maintaining the fairness among the users. We present different scheduling schemes including absolute throughput-based scheduling, normalized throughput-based scheduling, absolute SNR-based scheduling, and normalized SNR-based scheduling schemes. We use an antenna selection scheme to overcome the drawback of channel hardening in multiuser MIMO systems. This also improves the system performance and reduces the system complexity. Using mathematical analysis and numerical simulations, we compare the presented schemes and show their significant advantages.

Performance analysis of multiuser diversity with antenna selection in MIMO MRC systems

By combining adaptive modulation (AM) and automatic repeat request (ARQ) protocol, cross-layer design (CLD) scheme of multiuser MIMO system with antenna selection (AS) is presented. By means of exact expression of packet error rate (PER), the switching thresholds (STs) of fading gain subject to a target PER constraint are derived, which is more accurate than the conventional STs based on approximate PER expression. According to these results, and using mathematical manipulation, we obtain the tightly closed-form expressions of the average spectral efficiency (SE) and average PER. Simulation results show that the multiuser MIMO system with CLD-AS scheme using the derived STs provides higher SE than that using existing approximate STs while meeting the PER requirement. Besides, simulations for average SE and PER are in good agreement with the derived theoretical expressions, which demonstrates the validity of the theoretical analysis.

Despite significant research efforts, closed-form bit error rate (BER) expressions for multiple-input multiple-output (MIMO) systems employing transmit antenna selection and orthogonal space-time block codes (OSTBCs) are not available. We thus derive exact closed-form expressions for the BER of Gray-coded M-ary one and two-dimensional amplitude modulations when an OSTBC is employed and N transmit antennas out of total Lt antennas are selected for transmission. We also derive tight closed-form approximate BER for M-PSK constellations. Our BER expressions are valid for a frequency-flat Rayleigh fading MIMO channel and can be evaluated without numerical integration methods.

In this paper, we first address the effects of the feedback delay on a variable-rate variable-power adaptive modulation MIMO system that is designed under a perfect channel state information (CSI) assumption. Closed-form expressions for the average bit error rate (BER) and average spectral efficiency (ASE) are derived. Based on that, simple but effective adaptive modulation designs using the outdated instantaneous CSI and time correlation coefficient are proposed based on the signal-to-interference and noise ratio (SINK) and BER analysis. Analytical and simulation results show that these designs provide good trade-offs between the ASE and BER in an adaptive way, and make the adaptive MIMO system much more robust to the CSI imperfection

The performance analysis of multiuser multiple-input multiple-output (MIMO) system with rate-adaptive modulation and antenna selection over Rayleigh fading channels is presented. By means of exact expression of bit error rate (BER), the suboptimal switching thresholds (ST) of fading gain subject to a target BER constraint are derived. It is shown that this suboptimal ST are very close to the optimal ST, and is more accurate than the conventional ST based on approximate BER expression. By the ST, we obtain exact closed-form expressions of the spectrum efficiency (SE) and average BER. Moreover, a tightly approximate BER is derived to simplify the calculation of exact BER, which has more accuracy than the existing approximate BER. Simulation results for SE and BER are in good agreement with the derived theoretical expressions. The results show that the multiuser MIMO with adaptive modulation can provide better SE than the single user counterpart, and the system SE using suboptimal ST is also higher than that using conventional ST.

Smart antennas can greatly improve the performance of wireless communication systems by providing better link quality and immunity to interference. A simple smart antenna structure is fixed beamforming and beam selection. More complex structures require combining of the signals from multiple receivers. In this paper we compare the performance of beam and antenna selection and combining techniques. Our results are based on recently reported statistical and measurement based spatial channel models and in most cases include impact of co-channel interference. We derive the probability density function (pdf) of SINR in space- and frequency-selective multiple clustered Rayleigh fading channel with finite angle spread (AS). We also analyze the outage capacity and probability of beam selection in flat fading assuming both correlated and independent fading between the antennas. Our analysis also includes the impact of erroneous beam or antenna selection. Furthermore, theoretical bounds for a hybrid of beam/antenna selection and maximal ratio combining (MRC) are presented. We show that beam selection techniques can be very effective against both multipath fading and co-channel interference. We also show that simple fixed beamforming networks such as Butler matrices are nearly as effective as more complex fixed beamforming networks.

Transmit antenna selection is a promising technique to simplify hardware and computational complexity of MIMO wireless communication systems. In this paper, we derive expressions for outage probability and bit error rate of two-hop relaying systems incorporated with transmit antenna selection at source and relay node. A closed form expression for outage probability and an infinite expression for bit error rate are derived for two hop cooperative communication system for BPSK modulation scheme. In the analysis, received signals are assumed to be collection of signals received as a result of multiple reflections having a line of sight component. Such channels can be well approximated by к-μ fading distribution which is generalized assumption to model fading channels with a dominant or line of sight component. To analyze the performance of the system at high SNR conditions, the expression of asymptotic BER is also derived in closed form from the expression for exact BER. The transmit antenna is selected at the source and relay nodes such that the received signal to noise ratio at the destination node is maximized. Maximal ratio combining is considered at the relay and destination nodes. The bit error rate results obtained from analytical expressions and Monte Carlo simulations are plotted for different values of fading parameters, к and μ. The analytical results are found to be in close agreement with simulation results.

Classical MIMO system model without antenna selection and MIMO system model with antenna selection are presented. New quasi-optimal low complexity algorithms of antenna selection are proposed for MIMO communication systems. These algorithms allow to achieve high spectral efficiency without significant increase of complexity. The statistical modeling method is used to evaluate the efficiency of the proposed algorithms and to compare their characteristics with the characteristics of the known algorithms of full and partial combined selection. The computational complexity of the proposed algorithms is evaluated and been compared with the computational complexity of the well-known algorithms of full and partial combined selection in low-order and high-order MIMO system configurations. The possibility of practical application of new quasi-optimal algorithms in real communication systems is clearly demonstrated by comparative analysis of error-rate performance in conjunction with an assessment of computational complexity. These applications provide significantly improving of the energy performance of MIMO communication systems and it allows to improve quality characteristics of communications for subscribers or could be exchanged to the lower price of construction and maintenance of real communication systems.

Many generalized fading distributions are given in terms of special functions, complicating the analysis of wireless performance metrics. This paper presents novel approximations to the extended incomplete gamma function, the modified Bessel function of the second type, and the generalized Q-function. New simpler and unified form for the probability density function of the extended generalized-K (EGK) and M-N distributions is developed, avoiding complicated and computationally-expensive functions, e.g. Fox and Meijer-G. Based on the new unified PDF and the proposed approximations, we derive novel generic and unified expressions for the average bit error rate and average channel capacity for the recently introduced six most generalized fading channels, namely the EGK, the M-N, the α-η-μ, α-λ-μ, α-κ-μ, and α-λ-η-μ, including the generalized-K, generalized Nakagami-m, the α-μ, the η-μ, the λ-μ, the κ-μ, the Nakagami-Lognormal, the Weibull, the Rice, the Hoyt, the Maxwell and other fading scenarios as special cases. The Additive White Generalized Gaussian Noise (AWGGN) is considered as the noise model, that includes the AWGN, the Laplacian, the Gamma and the impulsive noise as special cases, being an application to the generalized Q-function approximation. Moreover, novel analysis for Space-Time Block Codes in generalized-K fading is also developed as an application to the developed approximation of the modified Bessel function. The derived expressions are very simple and analytically traceable. Monte Carlo simulation and published work corroborate our obtained results.

듀얼 홉 시스템에서 기존의 두 홉에 대한 채널 정보를 이용하여 가장 좋은 성능을 나타내는 중계 노드 선택 기법은 채널 피드백을 위한 자원의 소모가 크다. 본 논문에서는 듀얼 홉 디코딩 후 전달 중계 시스템에서 첫 번째 홉에 대한 채널 정보만을 필요로 하는 부분 중계 노드 선택 기법을 이용하여 정확한 평균 비트 오차율을 분석한다. 이 때, 독립적인 레일레이 페이딩 채널을 가정하여 M-ary QAM에 대한 정확한 비트 오차율의 표현식을 유도한다. 또한, 수치적 결과를 통해 두 홉에 대한 채널 정보를 이용하여 가장 좋은 성능을 나타내는 중계 노드 선택 기법과 부분 중계 노드 선택 기법에 대한 성능을 비교한다. 여기서, 중계 노드의 수와 첫 번째 홉과 두 번째 홉 간 평균 채널 전력비를 다양하게 가정하여 평균 비트 오차율을 분석한다. The conventional best relay selection based on all the channel information for the first and second hops in dual-hop systems has a large consumption of resources for channel feedback. In this paper, we analyze the average bit error rate for partial relay selection based on the channel information only for the first hop in dual-hop decode-and-forward relaying systems, where we assume independent Rayleigh fading channels. In particular, we provide an exact and closed-form expression for the average bit error rate of M-ary QAM. Also, through numerical investigation, the performance of the partial relay selection is compared with the performance of the best relay selection, and the performance is evaluated for different numbers of relays and various average channel power ratios for the first and second hops.

An exact and closed-form expression for the average bit error rate (BER) of coherent binary phase-shift keying (BPSK) using maximal ratio combining (MRC) in the presence of multiple cochannel interfering users is derived for correlated Rayleigh fading. Under the assumption that the branch gains of the desired user signal and interfering signals experience correlated Rayleigh fading with the same correlation eigenvector matrix, as is the case for receiver diversity in an omnidirectional scattering environment, this BER expression is valid for arbitrary correlation structure such as 2-D and 3-D channel correlation models, and applys for an arbitrary number of interfering users and an arbitrary number of receiver antennas.

In this paper, we consider a multiple-input-multiple-output system employing orthogonal space time block codes over a generalized fading model, namely, $$\eta - \mu$$ fading distribution. Simplified closed-form expressions for the probability density function and cumulative distribution function of the proposed system under absolute SNR scheduling have been derived in this paper. More specifically, new analytical expressions for average bit error rate and average channel capacity are derived for two cases: (a) independent and identically distributed (i.i.d) fading links and (b) independent and non-identically distributed (i.ni.d) fading links. Numerical evaluation shows improvement in system performance for various values of $$\eta$$ in format 1 with increase in the (a) number of users (U), (b) number of transmit antennas (n T ), and (c) number of receive antennas (n R ). The proposed mathematical analysis is verified using MATLAB numerical results which demonstrate the accuracy of theoretical approach.

Performance analysis of modulating retro-reflector FSO communication systems over Málaga turbulence channels

In this paper, we have investigated the performance of underwater vertical wireless optical communication (UVWOC) links employing on-off key modulation for selection combining based receive diversity schemes in the presence of underwater turbulence, pointing errors, and attenuation losses. Due to variations in temperature and salinity along the ocean's depth, turbulence-induced fading affects the performance of the underwater vertical wireless optical link. The vertical link of the underwater medium influenced by a strong turbulence regime is modeled using cascaded gamma-gamma distribution considering multiple non-identical layers along with attenuation losses and pointing errors. We have derived closed-form expressions for the average bit error rate (BER) and outage probability (OP) for the link employing multiple detectors at the receiving end. The accuracy of all of the closed-form expressions derived in this paper has been validated using Monte Carlo simulations.