Approximate BER Research Articles

A Rotated-Constellation Based Method for BER Analysis in Uplink NOMA Systems

Non-orthogonal multiple access (NOMA) is one of candidate technologies in the next generation radio access networks, in which the joint maximum-likelihood (JML) detector has the optimal estimation performance. In this paper, we propose a rotated-constellation based method to regularize the decision boundaries of received constellation. Through regular decision boundaries, we further derive the approximate closed-form BER expressions of uplink NOMA systems in Rayleigh fading channels. Numerical results verify the effectiveness of rotated-constellation based method and conform to our derivation. It is also shown through simulations that the proposed analysis method outperforms conventional method in terms of accuracy.

Design and Performance Analysis of a New STBC-MIMO LoRa System

LoRa is a modulation technology for low power wide area networks (LPWAN) with enormous potential in 5G era. However, the performance of LoRa system deteriorates seriously in fading-channel environments. To tackle this problem, in this paper we introduce multiple-input-multiple-output (MIMO) configuration employing space-time block coding (STBC) schemes into the LoRa system to formulate an STBC-MIMO LoRa system. Then, we investigate the theoretical performance of the proposed system over Rayleigh fading channels. To this end, we derive the distribution of the decision metric for the demodulator in the proposed system. Based on the above distribution, we propose a closed-form approximate BER expression of the proposed system when perfect and imperfect channel state information (CSI) are considered. Furthermore, we analyze the diversity order and the throughput of the proposed system. The results of the diversity analysis demonstrate that the diversity order of the system in the imperfect CSI scenario with fixed channel estimate error variance is zero. However, in the imperfect CSI scenario with a decreasing channel estimate error variance and the perfect CSI scenario, the system can achieve full diversity. In addition, the results of the throughput analysis show that the throughput of the proposed system is little affected by CSI conditions. Simulation results verify the accuracy of the theoretical analysis and the excellent performance of the proposed system. Due to such superiority, the proposed STBC-MIMO LoRa system can be considered as a good scheme for LPWAN.

네거티브 지수 대기 난기류 채널이 고려된 시공간 블록 코딩 기반 자유 공간 광학 통신 시스템의 닫힌 형태의 비트 오류율 근사식 유도

본 논문에서는 강한 대기 난기류 환경 하에서 피크 대 평균 광출력 비율 (PAOPR: Peak-to-Average Optical Power Ratio)의 증가로 오류 성능 향상을 가능케 하는 시공간 블록 코딩 (STBC: Space-Time Block Coding) 온오프 키잉 (OOK: On-Off Keying) 송신 방식이 적용된 자유 공간 광학 (FSO: Free-Space Optical) 시스템에 대한 평균 비트 오류율 (BER: Bit Error Rate)의 새롭고 효율적인 닫힌 형태의 근사식을 유도하고, 높은 신호 대비 잡음 비 (Signal-to-Noise-Ratio: SNR) 상황에서의 점근적 분석을 수행한다. 본 논문에서 도출된 성능 분석의 정확성은 다양한 시뮬레이션을 통해 검증되었고, 이를 통해 시공간 블록 코딩이 활용되는 다양한 실제 통신 환경에서 달성 가능한 다이버시티 차수(diversity order) 및 코딩 이득 (coding gain)에 대한 통찰력을 제공하고자 한다.

Effect of Subcarrier Activation Ratio on the Performance of OFDM-IM over Rayleigh Fading Channel

Orthogonal frequency division multiplexing with index modulation (OFDM-IM) is acquiring increasing attention due to its advantages over classical OFDM. These advantages include superior BER performance and transmit power saving since only a subset of the subcarriers is activated to transmit $M$ -QAM symbols and the remaining subcarriers are turned OFF. The vast majority of the literature studies the OFDM-IM by assuming certain subcarrier activation ratios, $r$ , together with other system parameters without figuring out the possible variation in system performance at other $r$ values. In this letter, the effect of $r$ and $M$ on the spectral efficiency (SE) and BER of OFDM-IM is investigated. An inequality is developed to maximize SE while power saving is maintained. Moreover, the BER performance of an OFDM-IM system exploiting a maximum subcarrier energy detector over multipath Rayleigh channel is analyzed. An approximate average BER expression is derived and the effect of $r$ and $M$ is discussed. Computer simulation has showed the validity of the derived expressions.

Performance Analysis and Interleaver Structure Optimization for Short-Frame BICM–OFDM Systems

Bit-interleaved coded modulation (BICM), together with orthogonal frequency-division multiplexing (OFDM) signaling, has found its application in many recent wireless standards. BICM-OFDM systems are able to simplify the design of coding and modulation with various information rates for link adaptation. Furthermore, they provide robustness against frequency-selective fading channels. The combination of BICM-OFDM and convolutional code turns out to be attractive as it allows for low complexity and low latency decoding architecture at the receiver. It has been known that the performance of convolutionally coded BICM-OFDM systems depends on the bit interleaver structure, but little attention has been paid for its theoretical performance analysis. In this paper, we develop a novel theoretical expression for approximate BER of convolutionally coded BICM-OFDM that can be used for evaluating the performance of a given bit interleaver structure, and propose a design guideline for its optimization. Numerical comparisons between the optimized interleaver that satisfies our guideline and other random and structured interleavers demonstrate the validity of our design criterion.

Approximate BER Performance Analysis of Coherent Amplify-and-Forward Cooperative Relay System with BPSK over Nakagami-m Fading Channels

Approximate BER Performance Analysis of Coherent Amplify-and-Forward Cooperative Relay System with BPSK over Nakagami-m Fading Channels

Unified Analysis of Multiuser Scheduling for Downlink MIMO Systems with Imperfect CSI

In this paper, unified BER performance and outage probability analyses of downlink multiuser scheduling for multiple-input multiple-output (MUS-MIMO) transmission/combining (transceiving) systems with imperfect channel state information (CSI) caused by feedback over Rayleigh fading channels is presented. The unified analysis is applicable to MIMO transceiving systems whose received signal-to-noise ratio (SNR) is given as largest order statistic of chi-square distribution. The performance of MUS-MIMO employing selective transmission/selective combining (ST/SC), ST/maximum ratio combining (MRC) and space-time block codes (STBC) can be analyzed by this general framework. Accurate and approximate unified closed-form BER and outage probability expressions of the MUS-MIMO transceiving system with normalized SNR-based scheduling in heterogeneous networks are derived. Based on the approximate BER and outage probability expressions, diversity gains are analyzed at high SNR. The results indicate that the MUS-MIMO for using the three transceiving schemes can achieve full diversity order for perfect CSI, while the diversity gain is degraded differently for the three transceiving schemes under imperfect CSI. Computer simulation shows that the theoretical analysis is in good agreement with simulation results, and the approximate BER expressions are very close to the accurate ones but with lower computational complexity.

Diversity order analysis of orthogonal space–time block coding over keyhole fading channels with antenna selection

SUMMARYAlthough there are many research results for the keyhole fading channels in the current literature, fewer results have investigated the antenna selection scheme and quantified the diversity order. In this letter, we first derive some simple statistics of the output signal‐to‐noise ratio for the orthogonal space–time block coding over keyhole fading channels. On the basis of these results, we derive an approximate BER expression for the keyhole MIMO channels with receive antenna selection scheme. Results show that the diversity order with receive antenna selection is min{nR,nT}for nR ≠ nT, which means that the full diversity order with antenna selection is maintained. Finally, numerical results demonstrate the accuracy of our analytical expressions and the tightness of approximate formulas. Copyright © 2012 John Wiley & Sons, Ltd.

Effect of Correlated Non-Gaussian Quadratures on the Performance of Binary Modulations

The received signal in many wireless communication systems comprises of the sum of waves with random amplitudes and random phases. In general, the composite signal consists of correlated nonidentical Gaussian quadrature components due to the central limit theorem (CLT). However, in the presence of a small number of random waves, the CLT may not always hold and the quadrature components may not be Gaussian distributed. In this paper, we assume that the fading environment is such that the quadrature components follow a correlated bivariate Student-t joint distribution. Then, we derive the envelope distribution of the received signal and obtain new expressions for the exact and high signal-to-noise (SNR) approximate average BER for binary modulations. It also turns out that the derived envelope pdf approaches the Rayleigh and Hoyt distributions as limiting cases. Using the derived envelope pdf, we investigate the effect of correlated nonidentical quadratures on the error rate performance of digital communication systems.

Viterbi-Type Inter-Carrier Interference Equalization for OFDM over Doubly Selective Channels

Orthogonal Frequency Division Multiplexing (OFDM) transmission is robust to frequency-selective channels but sensitive to time-selective channels. Time variations of channels generate inter-carrier interference (ICI), which degrades system performance. In this paper, we develop frequency-domain Viterbi-type algorithm to effectively suppress the ICI, by exploiting the property of ICI terms in OFDM symbols. Null subcarriers, which are embedded in OFDM symbols for the reduction of interferences from/to adjacent bands, are exploited to reduce the complexity of the algorithm. Then, an approximate BER expression of Viterbi-type equalizer is derived. Simulations are provided to show the Viterbi-type equalizer works well in time- and frequency-selective (doubly selective) channel with affordable complexity.

Efficient and robust decision delays selection scheme for multiuser MIMO DFE in power imbalance situation

Recently, it has been shown that the selection of decision delays has a crucial effect on the performance of finite-length multiple-input multiple-output decision-feedback equalization (MIMO-DFE) receiver for multiuser time division multiple access (TDMA) system. With the minimum joint-BER (MJB) criterion, choosing the optimum different decision delays for individual uplink users would require multi- dimensional searching, which is too costly for real-time applications. In this paper, we propose an efficient power-ratio-based (PRB) scheme to solve the multiuser decision delay problem in practice. First, it employs the MIMO channel responses to calculate the received power ratios among uplink users. The ratios are then compared to a set of preset thresholds to determine the decision delays. To optimize the thresholds, Gaussian approximation (GA) technique is used for speeding up the off-line searching process. Under power imbalance situation, we note that the decision delays must be carefully selected on a burst-by-burst basis, or else the performance loss for the weaker users would be very significant. Hence, both the MJB and PRB methods can resist the near-far effect. Finally, simulation results show that the proposed PRB scheme has an approximate BER performance, but with much reduced computational complexity, as compared to the optimal MJB one.

Approximate Minimum BER Power Allocation for MIMO Spatial Multiplexing Systems

Precoding for multiple-input multiple-output (MIMO) spatial multiplexing generally requires high feedback overhead and/or high-complexity processing. Simultaneous reduction in transmitter complexity and feedback overhead is proposed by imposing a diagonal structural constraint to precoding, i.e., power allocation. Minimum bit-error rate (MBER) is employed as the optimization criterion, and an approximate MBER (AMBER) power-allocation algorithm is proposed for a variety of receivers, including zero-forcing (ZF), successive interference cancellation (SIC), and ordered SIC (OSIC). While previously proposed precoding schemes either require ZF equalization for MBER, or use a minimum mean-squared error (MMSE) criterion, we provide a unified MBER solution to power allocation for ZF, SIC, and OSIC receiver structures. Improved error-rate performance is shown both analytically and by simulation. Simulation results also indicate that SIC and OSIC with AMBER power allocation offer superior performance over previously proposed MBER precoding with ZF equalization, as well as over MMSE precoding/decoding. Performance under noisy channels and power feedback is analyzed. A modified AMBER algorithm that mitigates error propagation in interference cancellation is developed. Compared with existing precoding methods, the proposed schemes significantly reduce both transmit processing complexity and feedback overhead, and improve error-rate performance

Approximate Minimum BER Power Allocation for MIMO Spatial Multiplexing Systems

Approximate Minimum BER Power Allocation for MIMO Spatial Multiplexing Systems

Approximate BER performance of generalized selection combining in Nakagami-m fading

The error performance of generalized selection combining (GSC), which optimally combines the K highest signal-to-noise ratio (SNR) signals out of L total diversity signals, in Nakagami-m fading was recently evaluated using moment generating function (MGF) of the GSC output SNR. However, no single closed-form expression for the MGF exists for arbitrary K and L. In fact, a closed-form expression for the MGF is possible only for an individual combination of K and L. In this letter, a single closed-form expression for approximating the MGF is, therefore, derived and employed in evaluating the approximate error performance. Although the approximation is only applicable for GSC with K being a factor of L, it nonetheless achieves a high degree of accuracy.

Evaluation of bit error rate and optimization of error correcting capability assignment for a diversity system with multilevel coding over a fading channel

In a fading channel without ISI, the approximate theoretical BER for a diversity reception system where multilevel coding is applied has been determined. The result obtained from the approximate theoretical BER method matches the simulation result, and thus this method can be used as an alternative for evaluating a coding system through simulation. Using the approximate theoretical BER method with a BCH code of length 31 and a rate of 63/93, the optimum error correcting capability assignments at BER = 10−6 for two and three branches have been determined. The error capability assignments (3, 2, 1), (5, 1, 1) have been found to be optimum for levels 1, 2, 3 of the block code, respectively. In the case of a channel with M intersymbol interference, it has been shown that the BER for a given SNR = η [dB] of an interleaving, adaptive equalization, multilevel coding combination system can be estimated using the approximate theoretical BER of an (M + 1) branch diversity whose SNR is η − 10 log10( M + 1) [dB] . © 1999 Scripta Technica, Electron Comm Jpn Pt 3, 82(6): 26–35, 1999

Approximate SIR and BER formulas for DS-CDMA basedon radiation pattern characteristics of adaptive antennas

Approximate formulas are presented for the signal to interference gain and the bit error rate when radiation pattern characteristics such as the beamwidth and average sidelobe level are considered for adaptive antennas in DS-CDMA. These formulas can be used to produce results easily for a range of ideal or effective values and hence provide a fast and simple way to evaluate the performance of an adaptive antenna in a DS-CDMA system.