Performance of antenna array systems with optimum combining in aRayleigh fading environment

The effect of cochannel interference on the performance of digital mobile radio systems in a Rayleigh fading environment is studied. The average bit error rate (BER) of an antenna array system with an optimum combining scheme that maximizes the output signal-to interference-plus-noise ratio is analyzed. BER expressions which are easy to evaluate numerically are derived for coherent binary phase-shift keying schemes in an environment with cochannel interference and noise     

Performance analysis of optimum combining in antenna array systems with multiple interferers in flat Rayleigh fading

In this letter, we examine the statistical distribution of the signal-to-interference-plus-noise ratio (SINR) of the optimum combining (OC) technique in receive-antenna diversity systems. We decompose the SINR into two components by projection onto the interference subspace for systems with more antennas than interferers. For the case when the number of interferers is larger than the number of antennas, upper and lower bounds on performance are provided.     

Outage probability analysis of antenna array using maximum ratio combining in spherically invariant fading environment

In this paper, the outage probability of maximum ratio combining (MRC) in the spherically invariant fading environment was analyzed. The study was done with and without consideration of the effect of noise. First, the probability density functions (pdf) of signal‐to‐interference plus noise ratio (SINR) and signal‐to‐interference ratio (SIR) were derived. In our derivation, the characteristic pdfs of spherically invariant random process (SIRP) corresponding to the interferences were assumed to be both different and identical. Moreover, both equal and different mean powers of interferences were considered. With the derived pdfs of SINR and SIR, the expressions of outage probability were computed. Numerical analysis was done using three numerical methods known as Gauss–Laguerre, Gauss–Hermite, and Gauss–Legendre integrations. It should be noted that SIRP, the generalization of Gaussian random process, is assumed to have K‐distribution, which is the generalization of Rayleigh. Our analysis was verified by comparing the outage probabilities of the considered environments with those of Rayleigh fading channel. From the numerical results, the derived outage probability converges to that of Rayleigh fading, when the shape parameter of characteristic pdf approaches infinity. Copyright © 2006 John Wiley & Sons, Ltd.     

Performance analysis of optimum combining with multiple interferersin flat Rayleigh fading

This paper is a performance analysis of optimum combining in the presence of multiple equal power interferers and noise when the number of interferers is less than the number of antenna elements. Desired signal and interferers are subject to flat Rayleigh fading, and the propagation channels are independent. An approximate expression of the probability density function of the output signal-to-interference-plus-noise ratio (SINR) is derived analytically. It is then applied to obtain the cumulative distribution function of the SINR, and the bit-error rate (BER) of some binary modulations, including coherent binary phase-shift keying. In the case of a single interferer, an exact analysis is performed to prove the validity of the approximation. In the case of multiple interferers, the accuracy of the approximation is assessed through simulations. Although limited to equipower interferers, this analysis is a convenient way of assessing the performance of optimum combining in some typical situations and comparing it with that of maximal-ratio combining. The final results are remarkably simple and provide a useful complement to previous analyzes, especially in the region of reasonably high BERs which are of practical interest     

Performance analysis of optimum combining in wirelesscommunications with Rayleigh fading and cochannel interference

Optimum combining for space diversity reception is studied in digital cellular mobile radio communication systems with Rayleigh fading and multiple cochannel interferers. This paper considers binary phase-shift keying (BPSK) modulation in a flat Rayleigh-fading environment when the number of interferences L is no less than the number of antenna elements N(L⩾N). The approach of this paper and its main contribution is to carry out the analysis in a multivariate framework. Using this approach and with the assumption of equal-power interferers, it is shown that the probability density function of the maximum signal-to-interference ratio (SIR) at the output of the optimum combiner has a Hotelling T² distribution. Closed form expressions using hypergeometric functions are derived for the outage probability and the average probability of bit error. Theoretical results are demonstrated by Monte Carlo simulations     

Performance of CDMA random access systems with packet combining in fading channels

We analyze the system performance of code-division multiple-access (CDMA) random access systems with linear receivers and packet combing in multipath fading channels. Both slotted and unslotted CDMA systems with random spreading codes are considered. The analysis is based on large systems in which both the offered load and the processing gain tend to infinity but their ratio is fixed. It is relatively easy to characterize the traffic in such large systems, which enables us to derive the system throughput and average delay. From the analysis results, it is observed that multiuser detection and packet combining substantially improve the system performance.     

Bit error rate reduction scheme for direct sequence CDMA in aRayleigh fading environment

A finite projective plane based time hopping scheme is presented for direct sequence CDMA with non-ideal power control in a Rayleigh fading environment. The advantages are two fold. First, the number of error bits is reduced significantly; secondly, the throughput is increased     

Performance analysis of optimum combining for dual-antenna diversity with multiple interferers in a Rayleigh fading channel

We study the performance analysis of optimum combiner for M-ary phase-shift keying (MPSK) with multiple interferers in a flat Rayleigh fading channel. The first-order approximation is considered for the dual-antenna diversity reception. We derive the analytical solutions for the ordered mean eigenvalues of interference-plus-noise covariance matrix and a simple closed-form expression for the average symbol error rate of MPSK in the case of multiple cochannel interferers.     

Performance analysis of MIMO systems with antenna selection over quasi-static fading channels

We analyze the performance of multiple-input-multiple-output (MIMO) systems with antenna selection over quasi-static fading channels. The basic idea is that, for a given number of receive antennas, M, the receiver uses the best L out of the available M antennas where, typically, L相似文献   

Capacity analysis of distributed antenna systems in MIMO Nakagami fading multicell environment

In this paper, the downlink capacity analysis of distributed antenna systems (DAS) with multiple receive antennas in Nakagami-m fading multicell environment is presented. According to the performance analysis, and using mathematical manipulation, we derive the probability density function (PDF) of the effective signal to interference plus noise ratio of the system. Based on the obtained PDF, an exact closed-form expression of DAS capacity is derived. This expression includes the existing capacity expression as a special case, and avoids the error in the latter. Thus, it can provide good theoretical performance evaluation for downlink DAS. Computer simulation shows that the theoretical analysis is in good agreement with simulation result. Moreover, the increase of receive antenna and/or Nakagami fading parameter m can improve the capacity effectively.     

Performance of space-frequency combining at the antenna array of a MC-CDMA system

In this paper, a multicarrier code-division multiple-access (MC-CDMA) system employing antenna array at base station with quaternary phase shift keying (QPSK) modulation is proposed. This receiver adopts a space-frequency two-dimensional (2-D) Rake receiver structure. Based on the detailed analysis of the interference characteristics of the proposed system, the bit error rate (BER) performance of the system is provided. With regard to spatial domain combining, the optimum and suboptimum combining weight is derived, while the suboptimum set of weights is simplified on sense of that only the knowledge of array vector of desired user alone is sufficient for the combining. Simulation results verify the analysis and show that better performance is achieved for the proposed antenna array MC-CDMA system than the corresponding single antenna approach.     

Performance analysis of square arranged antenna array with SC and MRC receiver over Nakagami fading channel

In this paper, the performance of using a square array of four antennas for selection combining (SC) and maximal-ratio combining (MRC) of Nakagami correlated signals is investigated. The closed form of average output signal-to-noise ratio and bit error rate (BER) for SC with arbitrary four correlated branches is derived; the expression of BER with MRC is also derived by utilizing the characteristic function method. Two models for the angle of arrival (AOA), i.e., uniform and truncated Gaussian, are considered in the system performance evaluation. The effects of correlation coefficients and fading factor on the system performance are investigated through numerical examples, which show that the uniformly distributed AOA system outperforms the truncated Gaussian-distributed counterpart with small angular spread. The degradation of system performance in the presence of one-antenna failure is also investigated.     

Hard-limited versus linear combining for frequency-hopping multiple-access systems in a Rayleigh fading environment

In comparing two proposed frequency-hopping mobile radio systems for digitized speech, Goodman et al. have observed that the system employing multiple frequency-shift keying (MFSK) can accommodate many more users than the one with differential phase-shift keying (DPSK). Besides the difference in modulation methods, the MFSK system uses hard-limited combining while the DPSK one uses linear combining. Upper bounds are obtained on the probability of error for DPSK systems with hard-limited combining and linear combining. These bounds suggest that the DPSK system with hard limiters can support about twice as many users as the original one.     

Performance analysis of coded communication systems on Nakagami fading channels with selection combining diversity

In this paper, we develop analytical tools for the performance analysis of coded, coherent communication systems on independent and identically distributed Nakagami-m fading channels with selection combining (SC) diversity. First, we derive an exact expression for the moment generation function (MGF) of the signal-to-noise ratio (SNR) of a code symbol at the output of the selection combiner. Next, based on Gauss-Chebyshev quadrature and Gauss-Laguerre quadrature rules, we propose a simple to compute, yet accurate, numerical solution for the pairwise error probability (PEP) of coded M-phase-shift keying (PSK) signals. Using the PEP expressions, we present the union bound-based bit-error performance of trellis-coded modulation schemes and turbo codes. Finally, we derive an exact expression for the computational cutoff rate of a coded system with M-PSK signaling and SC diversity, and show that the cutoff rate expression is a simple function of the MGF of the SNR at the output of the diversity combiner.     

存在共道干扰的多径衰落环境中手机双天线系统性能研究

将城市室外电波传播模型、手机天线本征激励方向图以及信号合并方式相结合,建立了分析在具有共道干扰的多径衰落环境中手机双天线系统的性能模型。用这一模型研究了采用最优合并方式的手机上双单极子天线系统的性能,分析了合并性能受共道干扰强度、天线互耦以及机身的影响。     

Performance of UWB multiple-access impulse radio systems with antenna array in dense multipath environments

In this letter, the influence of temporal and spatial diversities on the performance of ultra-wideband time-hopping pulse-position modulated multiple-access impulse radio (IR) systems is analyzed. We investigate how an antenna array can be used at the receiver to improve the bit-error rate (BER) performance and can cope with the effects of multiple-access interference of IR system in dense multipath environments. Analytical and simulation results show that the BER performance of the IR systems can be improved when the number of array elements is increased. The performance can be further improved by coherently adding more multipaths at the receiver.     

On antenna array receiver principles for space-time-selectiveRayleigh fading channels

Optimum (in the sense of minimum-error probability) single-symbol diversity detection for fading, noisy channels is too complex for practical implementation. A simplified, near-optimum array receiver is proposed, which is based on the statistics (i.e., the covariance-function matrix) of the fading channel. This detector is then analyzed by calculating the exact error probability. When there is a spread of the direction of arrival of the incident radio waves, the proposed detector significantly gains over an adaptive antenna array (which forms a weighted sum of the received antenna signals). Also, for this adaptive array, a fundamental difference between maximum-likelihood weights and least-mean-square weights is observed     

Performance analysis of multicarrier CDMA systems with frequency offsets and random spreading under optimum combining

The carrier-frequency offset effect on the performance of asynchronous multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA) systems with aperiodic random spreading and correlated Rayleigh fading is studied in this paper. We obtain the optimum combining filter that maximizes the signal-to-interference-plus-noise ratio (SINR) of the combined statistics and exploits correlated information among subchannels. A closed-form expression for the unconditional covariance matrix of the interference-plus-noise vector, which forms the basis of our theoretical analysis of the maximum SINR and the average bit error probability formula, is derived by averaging several random parameters including asynchronous delays, correlated Rayleigh fading, and signature sequences. The analytic results obtained are applicable to MC-CDMA with appropriate modifications. Furthermore, we show that the MC-CDMA system with a common random signature sequence over all subcarriers for a given user outperforms that with distinct sequences over different subcarriers. Finally, the performance of MC-CDMA systems using the optimum combining technique is compared with that of different combining filters in the simulation.     

Exact closed-form performance analysis of optimum combining with multiple cochannel interferers and Rayleigh fading

A new closed-form expression is derived for the exact bit-error probability (BEP) for optimum combining with binary phase-shift keying. The exact BEP expression is for multiple, equal power, cochannel interferers and multiple reception branches. It is assumed that the aggregate interference and noise is Gaussian and that both the desired signal and interference are subject to Rayleigh fading. The derivation starts by expressing the optimum combining decision statistic as a sum of quadratic forms of Gaussian random variables and it proceeds to average over the fading interference. The new BEP expression has low complexity as it contains only finite sums and products.     

Analysis of asynchronous FFH-MA systems with a hard-limited combining in Rayleigh fading

The bit error rate (BER) performance of the asynchronous fast frequency hopping multiple access (AFFH-MA) system with multiple hops per symbol is investigated considering the noncoherent M-ary frequency shift keying (MFSK) modulation and hard-limited linear combiner in Rayleigh fading. We present a method for the accurate evaluation of the BER of the AFFH-MA system, and verify the analytic works by Monte Carlo simulations.