Area spectral efficiency of soft-decision space–time–frequency shift-keying-aided slow-frequency-hopping multiple access

Slow-frequency-hopping multiple access (SFHMA) can provide inherent frequency diversity and beneficially randomize the effects of cochannel interference. It may also be advantageously combined with our novel space-time–frequency shift keying (STFSK) scheme. The proposed system’s area spectral efficiency is investigated in various cellular frequency reuse structures. Furthermore, it is compared to both classic Gaussian minimum shift keying (GMSK)-aided SFHMA and GMSK-assisted time- division/frequency-division multiple access (TD/FDMA). The more sophisticated third-generation wideband code-division multiple access (WCDMA) and the fourth-generation Long Term Evolution (LTE) systems were also included in our comparisons. We demonstrate that the area spectral efficiency of the STFSK-aided SFHMA system is higher than the GMSK-aided SFHMA and TD/FDMA systems, as well as WCDMA, but it is only 60% of the LTE system

Performance Model for MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

RTUWO Advances in Wireless and Optical Communications 2015 (RTUWO 2015). 5-6 Nov Riga, Latvia.This paper presents a performance model of the packet reception process in a wireless link with one antenna transmitter and a multiple-antenna maximum-ratio combining (MRC) receiver. The objective is to address the performance evaluation of multiple antenna systems enabled with adaptive modulation and coding (AMC). Two main assumptions are used: 1) Rayleigh fading correlated channels, and 2) imperfect (outdated) channel state information at the transmitter side (CSIT). The results presented here suggest that spatial correlation not always affects the performance of the MRC receiver: at low signal-to-noise ratio (SNR), correlation can improve performance rather than degrading it. By contrast, at high SNR, correlation is found to always degrade performance. At high SNR, correlation tends to worse the degrading effects of imperfect CSIT, particularly when the number of antennas increases. Imperfect CSIT causes errors in the assignment of MCSs, thus reducing throughput performance. These errors become more evident at high SNR, particularly when the values of branch correlation and the number of antennas increase

Bandwidth-efficient pilot-symbol-aided technique for multipath-fading channels

Pilot-symbol-aided (PSA) transmission is one of the effective methods to combat multipath fading in digital mobile communications systems. In the PSA systems, redundant bandwidth and power are required to transmit the pilot symbols. In this paper, we propose a novel fading estimation technique that requires a very low bandwidth redundancy in the PSA systems. The proposed technique uses simple linear interpolation on the pilot symbols and the detected data symbols to obtain the estimates of the channel fading effects. Monte Carlo computer simulation has been carried out to study the effects of the technique on the bit error rate performance of 16-ary quadrature amplitude modulation in the flat and the frequency-selective Rayleigh-fading channels corrupted with cochannel interference and additive white Gaussian noise. Results have shown that the proposed technique can, at the expense of a little power efficiency, significantly improve the bandwidth efficiency of the PSA systems using receivers with low com plexity and latency.published_or_final_versio

Probability of Error of Linearly Modulated Signals with Gaussian Cochannel Interference in Maximally Correlated Rayleigh Fading Channels

We evaluate the probability of error of linearly modulated signals, such as phase-shift keying (PSK) and quadrature amplitude modulation (QAM), in the presence of Gaussian cochannel interference (CCI) and Rayleigh fading channels. Specifically, we assume that the fading channel of the CCI is maximally correlated with the fading channel of the signal of interest (SOI). In practical applications, the maximal correlation of the CCI channel with the SOI channel occurs when the CCI is generated at the transmitter, such as the multiuser interference in downlink systems, or when a transparent repeater relays some thermal noise together with the SOI. We analytically evaluate the error probability by using a series expansion of generalized hypergeometric functions. A convenient truncation criterion is also discussed. The proposed theoretical approach favorably compares with alternative approaches, such as numerical integration and Monte Carlo estimation. Among the various applications of the proposed analysis, we illustrate the effect of nonlinear amplifiers in orthogonal frequency-division multiplexing (OFDM) systems, the downlink reception of code-division multiple-access (CDMA) signals, and the outdoor-to-indoor relaying of Global Positioning System (GPS) signals

Joint Beamforming, Terminal Scheduling, and Adaptive Modulation with Imperfect CSIT in Rayleigh Fading Correlated Channels with Co-channel Interference

The Second International Conference on Advances in Signal, Image and Video Processing - from Sensing to Applications (SIGNAL 2017). 21 to 25, May, 2017, 5Gsignalwave. Barcelona, Spain.—This paper presents a resource allocation algorithm for multi-user wireless networks affected by co-channel interference. The analysis considers a network with one base station (BS) that uses a multiple antenna transmitter (beamformer) to schedule (in a time-division manner) transmissions towards a set of J one-antenna terminals in the presence of K persistent interferers. The transmitter is assumed to employ MaximumRatio Combining (MRC) beamforming with spatially-correlated branches and channel envelopes modelled as Rayleigh-distributed processes. The BS has access to an imperfect (outdated) copy of the instantaneous Channel State Information (CSI) of each terminal. Based on this CSI at the transmitter side (CSIT), the BS proceeds to select (at each time interval or time-slot) the terminal with the highest channel strength for purposes of transmission. This imperfect CSIT is also used to calculate the coefficients of the beamformer that will be used to transmit information towards the scheduled terminal, as well as for selecting the most appropriate modulation format (threshold-based decision). In addition, the transmission towards each scheduled terminal is assumed to experience persistent co-channel interference that will degrade the quality of the information reception process. The main merits of this work are the following: 1) joint analysis of MRC-based beamforming, terminal scheduling based on maximum channel strength, and modulation assignment, and 2) joint modelling of the effects of spatial correlation, co-channel interference and imperfect CSIT. Results suggest that scheduling helps in rejecting co-channel interference and the degrading effects of imperfect CSIT. Spatial correlation could some times lead to better performance than the uncorrelated case, particularly in the low SNR (Signal-to-Noise Ratio) regime. Conversely, uncorrelated branches always outperform the correlated case in the high SNR regime. The use of higher numbers of antennas also improve performance of the system. However, spatial correlation tends to accumulate over the antenna array thus leading to a more noticeable performance degradation and more allocation errors due to the outdated CSIT assumption.info:eu-repo/semantics/publishedVersio

The Effect of Macrodiversity on the Performance of Maximal Ratio Combining in Flat Rayleigh Fading

The performance of maximal ratio combining (MRC) in Rayleigh channels with co-channel interference (CCI) is well-known for receive arrays which are co-located. Recent work in network MIMO, edge-excited cells and base station collaboration is increasing interest in macrodiversity systems. Hence, in this paper we consider the effect of macrodiversity on MRC performance in Rayleigh fading channels with CCI. We consider the uncoded symbol error rate (SER) as our performance measure of interest and investigate how different macrodiversity power profiles affect SER performance. This is the first analytical work in this area. We derive approximate and exact symbol error rate results for M-QAM/BPSK modulations and use the analysis to provide a simple power metric. Numerical results, verified by simulations, are used in conjunction with the analysis to gain insight into the effects of the link powers on performance.Comment: 10 pages, 5 figures; IEEE Transaction of Communication, 2012 Corrected typo

Performance Analysis of MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

This paper addresses the performance analysis of an adaptive wireless link with one antenna transmitter and a multiple antenna maximum-ratio combining (MRC) receiver. Two main assumptions are used in this paper: (1) Rayleigh fading correlated channels (i.e., MRC branch correlation) and (2) imperfect (outdated) channel state information at the transmitter (CSIT) side. he main contribution of this work lies in the derivation of analytic expressions (in terms of a series expansion) of the statistics of correct packet reception conditional on the decisions made by the transmitter based on outdated CSIT. he novelty of this derivation is the joint modelling of spatially correlated branches, imperfect CSIT, and adaptive modulation based on threshold-trigger decision. Contrary to common belief, the results presented here suggest that spatial correlation not always afects the performance of the MRC receiver: at low signal-to-noise ratio (SNR), correlation can improve performance rather than degrading it. In contrast, at high SNR, correlation is found to always degrade performance. At high SNR, correlation tends to worse the degrading efects of imperfect CSIT, particularly when the number of antennas increases. Imperfect CSIT causes errors in the assignment of MCSs, thus reducing throughput performance. hese errors become more evident in the high SNR regime, particularly when the values of branch correlation and the number of antennas increase.info:eu-repo/semantics/publishedVersio