Ordered Successive Interference Cancellation Research Articles

NOMA for Integrating Sensing and Communications towards 6G: A Multiple Access Perspective

This article focuses on the development of integrated sensing and communications (ISAC) from a multiple access (MA) perspective, where the idea of non-orthogonal multiple access (NOMA) is exploited for harmoniously accommodating the sensing and communication functionalities. We first reveal that the developing trend of ISAC is from orthogonality to non-orthogonality, and introduce the fundamental models of the downlink and uplink ISAC while identifying the design challenges from the MA perspective. (1) For the downlink ISAC, we propose two novel designs, namely NOMA-empowered downlink ISAC and NOMA-inspired downlink ISAC to effectively coordinate the inter-user interference and the sensingto- communication interference, respectively. (2) For the uplink ISAC, we first propose a pure-NOMA-based uplink ISAC design, where a fixed communication-to-sensing successive interference cancellation order is employed for distinguishing the mixed sensing-communication signal received over the fully shared radio resources. Then, we propose a general semi-NOMA-based uplink ISAC design, which includes the conventional orthogonal multiple access-based and pure-NOMA-based uplink ISAC as special cases, thus being capable of providing flexible resource allocation strategies between sensing and communication. Along each proposed NOMA-ISAC design, numerical results are provided for showing the superiority over conventional ISAC designs.

Joint design of ordered QR precoding and SIC detection for MIMO VLC systems.

Ordered successive interference cancellation (OSIC) detection has been investigated to mitigate the high spatial correlation for multiple-input multiple-output (MIMO) visible light communication (VLC) systems. However, existing OSIC schemes have to perform reordering and matrix inversion for each detected symbol, which may lead to high complexity when a large number of symbols are transmitted. In this work, a joint design of ordered QR decomposition precoding and SIC detection (OQR-SIC) is proposed for MIMO VLC systems. This work jointly investigates OQR precoding and SIC detection to reduce the detection complexity while alleviating spatial correlation issue for MIMO VLC systems. In OQR-SIC, with the upper triangular matrix obtained by QR decomposition, the SIC detector can detect the symbol sequentially without reordering and matrix inversion calculations. To improve the system data rate, we further optimize the ordering of the columns of the channel matrix before QR decomposition and the power allocation of transmitted signals under the constraints of dimming control, total electrical power and reliable SIC detection. Simulation results demonstrate that the proposed OQR-SIC achieves 2 dB and 9.8 dB signal-to-noise ratio gains compared to conventional QR-SIC in 4 × 4 and 9 × 9 MIMO VLC systems, respectively, when the bit error rate is 10-3.

Near-Optimal Performance With Low-Complexity ML-Based Detector for MIMO Spatial Multiplexing

In Spatial Multiplexing MIMO systems, many powerful non-linear detection techniques as sphere decoding have emerged to overcome the performance limitations of linear detection techniques. However, these non-linear techniques suffer from high complexity that increases dramatically with the number of antennas and the modulation order. Hence, they cannot be implemented on highly parallel hardware architecture and are thus not suitable for real-time high data rate transmission. In this letter, a new detection technique is proposed to approach the optimal performance obtained by Maximum Likelihood (ML) detector without increasing the complexity significantly. This detector is denoted by OSIC-ML since it combines two techniques: the Ordered Successive Interference Cancellation (OSIC) and the ML. The proposed OSIC-ML detector shows a near-optimal performance at very low complexity even with large scale MIMO and imperfect channel estimation, where this complexity can be efficiently controlled to achieve the desired complexity-performance tradeoff.

Performances of OSIC Detector of an UpLink OFDM Massive-MIMO System in Rayleigh and Ricain Fading Channels

This paper presents a least squares channel estimation for Massive-Multiple-Input Multiple- Output (Massive-MIMO) systems in next generation of wireless communications denominated 5G, combined with Orthogonal Frequency Division Multiplexing (OFDM) and 64-QAM modulation. In this paper, after determining the estimated channel, we first consider one OFDM symbol and presented the flat fading and the frequency-selective fading in the case when channel taps equal to one and strictly superior to one respectively. In addition to that, we consider the uplink transmission where the transmitter antenna equal to $$N_t=50$$ and a Base Station (BS) equipped with several antenna superior to that of transmitter, in the same way the data detected using a linear detectors Zero-Forcing and Minimum Mean Square Error. Moreover we improve their performance by an ordered successive interference cancellation (OSIC) method. Using two channels fading namely the Rayleigh and the Ricain respectively and evaluate their performance with a system of Massive-MIMO antenna. Increasing the number of channel taps increase the inter-symbol interference allows to degrade the performance of the system both the Rayleigh and Rician channel, even we used a pilot sequence equipowered, equispaced and phase shift orthogonal. Hence increasing the number of antennas arrays at the receiver (i.e BS) decreases more the Bit Error Rate, consequently increasing the performance of the system. the OSIC methods provide a best performance when the number of antenna grow in a smaller range of Signal-to-Noise Ratio.

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Modified ordered successive interference cancellation MIMO detection using low complexity constellation search

High spectral efficiency, large capacity, and high data rate make large-scale Multiple-Input Multiple-Output (MIMO) systems more prominent in 5G communication. Existing MIMO detection schemes like Maximum Likelihood (ML) achieves optimal performance, but it is significantly affected by exponentially increasing computational complexity. On the other hand, linear MIMO detection techniques have low complexity. However, these cannot be implemented in practical systems due to poor performance. Ordered Successive Interference Cancellation (OSIC) addresses these issues as it possesses intermediate and suboptimal performance but it faces erroneous symbols due to wrong selection of order. At first, OSIC K-correction algorithm is employed to resolve OSIC issues by replacing the user-defined K symbols in the search subspace of OSIC symbol vector and detects the symbol in terms of better likelihood metric. In addition, it proposes Reduced Complexity (RC) OSIC K-correction scheme that further reduces the computational complexity in OSIC K-correction by exploiting the deviation vector which focuses to opt and detect only the most erroneous symbols. The proposed algorithms offer an adequate trade-off between computational complexity and detection performance.

Performance of OQAM/GFDM in Spatial Multiplexing MIMO Systems

Generalized frequency division multiplexing (GFDM) is a prominent candidate to be used by the mobile Fifth Generation (5G) physical layer. Nevertheless, the integration of GFDM with Spatial Multiplexing (SM) MIMO system is essential to fulfill the data rate requirements. SM detection of MIMO-GFDM becomes a more challenging topic because of ICI and ISI due to the non-orthogonal nature of GFDM, along with IAI. In this article, the authors propose a system that combines the Offset-Quadrature Amplitude Modulation (OQAM) with GFDM to mitigate self-induced interference, by using a simple Matched Filter (MF) detector and minimum additional processing at the receiver. Simulation results show a considerable achieved improvement in BER by the proposed OQAM/GFDM compared to QAM/GFDM when using MMSE-based Ordered Successive Interference Cancellation (OSIC) detector. Furthermore, this system is unaffected by the roll-off factor variations of used pulse-shaping filters.

Cluster-Based Joint Resource Allocation with Successive Interference Cancellation for Ultra-Dense Networks

Due to the random deployment and the decreasing coverage of numerous base stations (BSs), the interference, including co-tier interference and cross-tier interference, is increasingly severe in ultra-dense networks (UDNs), which has negative effects on the communication quality. Considering all types of interference, we propose an interference management scheme aiming at maximizing the system capacity by jointly interference graph based clustering algorithm, suboptimal heuristic algorithm and ordered successive interference cancellation (OSIC) detection algorithm for UDNs. The analysis and simulations show that the average capacity and spectral efficiency of the proposed scheme have been improved compared with the optimal femto base stations subchannel allocation (OFBSSA) scheme and cluster-based FBS subchannal allocation (CFBSSA) scheme. The results also verify that the proposed scheme outperforms these two schemes in the following network scenarios: plenty of users located in overlapping region, a great many FBSs located in overlapping region, numerous FBSs and a large amount of users with random distributions, and it owns preponderances in meeting the requirements of 5G communication.

Cooperative OSIC System to Exploit the Leakage Power of MU-MIMO Beamforming based on Maximum SLR for 5G

This study investigated the crucial—but not welldiscussed—issues involved in designing beamforming for all receivers, subject to leakage power constraints. Our assumption is that all users use ordered successive interference cancellation (OSIC) detection when the channel state information (CSI) is available. The problem of interest is to find beamforming that can improve OSIC performance of a multi-user scheme without significantly increasing the complexity. This study considers the transceiver design for multi-user MIMO (MU-MIMO) communications, in which a single transmitter adopts beamforming to simultaneously transmit information at first time-slot. During the second time-slot, receivers cooperate to share specific results of OSIC detection in each user. We propose the maximum-likelihood (ML) to estimate the received symbols.The estimated symbols will be used in OSIC detection to detect interference symbols. Promising results show that our cooperative OSIC scheme of the MU-MIMO beamforming system based on maximum signal-to-leakage ratio (SLR) realizes the diversity order of OSIC. Also, by utilizing leakage power as a useful power and not just as an interference power, the performance of the proposed scheme over Rayleigh and Rician channels is significantly better than the performance of classical MU-MIMO beamforming system based on SLR at a high signalto-noise ratio (SNR).

Adaptive Modulation and Superposition Coding for MIMO Data Transmission Using Unequal Error Protection and Ordered Successive Interference Cancellation Techniques

This paper proposes and discusses an efficient multiple input multiple output (MIMO) system for adaptive modulation coding (AMC) based on unequal error protection (UEP) and superposition coding (SPC) by exploiting the features of sub channel partitioning. Using AMC, an appropriate order of modulation and code rate to suit the channel state information (CSI) can be selected. The realization of UEP is achieved through adaptive allocation and transmission of high and low-priority data signals over high and low quality sub channels respectively. A multistage decoding (MSD) receiver with the ordered successive interference cancellation (OSIC) technique is employed in the receiver by using two linear receiver signal combiner (RSC) techniques: zero-forcing (ZF) and minimum mean square error (MMSE). The data priority can be distinguished by the signal-to-noise ratio (SNR) and can be categorized as mode-B and mode-G. The simulation results show that the SNR performance enhancement for the UEP- MIMO scheme is approximately 9.4 dB compared to the others schemes. In addition, for the UEP-MIMO scheme, the overall data system transmission from mode-B outperforms that of mode-G with SNR gains of 8.2 dB compared to the 7.5 dB for the UEP-SISO scheme. Also, MMSE-SPC also outperforms the ZF-SPC with a 3 dB SNR at a bit error rate (BER) of 10-3.

A signal power adaptive regularized sphere decoding algorithm based multiuser detection technique for underdetermined OFDM/SDMA uplink system

SummaryThis work considers a regularized Fincke‐Pohst Sphere Decoder (R‐FSD) to detect the multiuser data of orthogonal frequency division multiplexing/space division multiple access (OFDM/SDMA) uplink system with underdetermined and rank‐deficient channel. Rank‐deficiency of the detected channel coefficients makes error‐free multiuser detection (MUD) a difficult task. In literature, most of the papers deal with either a determined or over‐determined full‐rank system. The method proposed in this work transforms an original ill‐posed least squares (LS) problem to a well‐posed one at the receiver, by using the standard Tikhonov regularization method. This is an efficient, direct, and less complex approach where the channel is modified using a regularization parameter that adapts to the signal power at the receiver. The result obtained is compared with maximum likelihood (ML), zero forcing (ZF), minimum mean squared error (MMSE) and ordered successive interference cancellation (OSIC) based detection techniques.

‐Fair resource allocation in non‐orthogonal multiple access systems

A non-orthogonal multiple access (NOMA) system is now considered as a promising radio access technique for next-generation networks owing to its benefits, e.g. spectral efficiency improvement. Due to the successive interference cancellation order at receivers, fairness among users in NOMA may not be guaranteed. In this study, the authors focus on α -fair resource allocation in NOMA. The complexity of the considered problem is then analysed. In particular, the problem is shown to be convex when 1 ≤ α < ∞ and α = ∞ , non-deterministic polynomial-time (NP)-hard when 0 < α < 1 , and polynomial-time solvable when α = 0 . Finally, simulation results are provided to examine the effects of the fairness degree on the system performance and verify the effectiveness of the proposed algorithms.

Joint channel estimation and equalization for MIMO-SCFDE systems over doubly selective channels

This paper considers a novel joint channel estimation and equalization (JCEE) algorithm for multiple-input-multiple-output single-carrier frequency-domain-equalization (MIMO-SCFDE) system over doubly selective channels for the first time. Given that the doubly selective channels can no longer support the assumption that the channel frequency-domain response remains invariant for the duration of one block, most of the channel estimation methods cannot be applied directly in it. And the lack of the information interaction between channel estimation and channel equalization degrades the overall performance. We put forward a noise-eliminated minimum-mean-square-error channel estimation (MMSE-CE) algorithm for the initialization, which is then utilized for iterative processing using the ordered successive interference cancellation (OSIC) technique. Analysis and simulation results validate the improved performance of the proposed JCEE algorithm for MIMO-SCFDE systems over doubly selective channels.

Nonlinear iterative precoding algorithm for MIMO multiuser systems

A modification of the known linear precoding algorithm CLTD (closed-loop transmit diversity) intended for multiuser radio communication systems and using theMIMOtechnology has been proposed. The efficiency of the original precoding algorithm CLTD possessing a number of advantages as compared to earlier precoding methods based on complete information about the communication channel state is enhanced at the expense of introducing nonlinearity. The use of nonlinear procedure of ordered successive interference cancellation (OSIC) in forming the precoding matrix makes it possible to significantly increase the noise immunity of the entire system as a whole at the expense of a slight rise of algorithm computational complexity. In addition, the results of computer simulation are presented reflecting the efficiency of the proposed modification of the algorithm for forming a precoding matrix as compared to the original CLTD algorithm.

On Multiple-Input Multiple-Output OFDM with Index Modulation for Next Generation Wireless Networks

Multiple-input multiple-output orthogonal frequency division multiplexing with index modulation (MIMO-OFDM-IM) is a novel multicarrier transmission technique which has been proposed recently as an alternative to classical MIMO-OFDM. In this scheme, OFDM with index modulation (OFDM-IM) concept is combined with MIMO transmission to take advantage of the benefits of these two techniques. In this paper, we shed light on the implementation and error performance analysis of the MIMO-OFDM-IM scheme for next generation 5G wireless networks. Maximum likelihood (ML), near-ML, simple minimum mean square error (MMSE) and ordered successive interference cancellation (OSIC) based MMSE detectors of MIMO-OFDM-IM are proposed and their theoretical performance is investigated. It has been shown via extensive computer simulations that MIMO-OFDM-IM scheme provides an interesting trade-off between error performance and spectral efficiency as well as it achieves considerably better error performance than classical MIMO-OFDM using different type detectors and under realistic conditions.

MIMO Detectors Under Correlated Channels

Este artigo analisa o desempenho de detectores com múltiplas antenas transmissoras e múltiplas antenas receptoras (MIMO – multiple-input multiple-output) em canais com desvanecimento correlacionados. Dois esquemas de detecção MIMO denominados erro quadrático médio mínimo (MMSE – minimum mean squared error) – com ou sem a etapa de cancelamento de interferência sucessiva ordenado (OSIC – ordered successive interference cancellation) – e técnica de redução treliça (LR – lattice reduction) são analisados e comparados com o limite de detecção de máxima verossimilhança (ML – maximum likelihood) em cenários específicos de interesse: (a) com incremento da eficiência espectral através do aumento do número de antenas. (b) quando há aumento nos índices de correlação de desvanecimento do canal. Neste contexto, o desempenho do detector ótimo ML-MIMO é utilizado como referência visando caracterizar o comportamento da taxa de erro de bit (BER) destes detectores MIMO e quão próximo esses estão do desempenho ML-MIMO.

Low-complexity OSIC equalization for OFDM-based Vehicular Communications

Vehicular communication systems are usually equipped with orthogonal frequency division multiplexing (OFDM) transceivers that operate on rapidly changing radio propagation environments, which results in high Doppler and delay spreads. More specifically, in these environments, the experienced channels are doubly selective and introduce severe intercarrier interference (ICI) at the receiver. An effective ICI mitigation technique is desired as a constituent part of an ordered successive interference cancellation (OSIC) architecture, which turns out to be computationally efficient, since it may require the solution of linear systems with multiple right-hand sides. To decrease the complexity, several techniques suggest mitigating the ICI by considering only a small number of adjacent subcarriers. However, this approximation introduces an error floor, which may result in unacceptable bit error rates (BER) at high signal-to-noise ratio regimes. In this paper, we propose a new OSIC equalization technique based on an iterative Galerkin projection-based algorithm that reduces the computational cost without sacrificing the performance gains of the OSIC architecture. Furthermore, we suggest a new serial/parallel cancellation architecture that extends the OSIC and has the potential to completely cancel the experienced ICI introduced in high-mobility scenarios. Extensive Monte Carlo experiments have been carried out to validate the accuracy of our framework, revealing intriguing tradeoffs between achieved BER and complexity, and highlighting the importance of designing low-complexity OSIC schemes for OFDM systems operating over double selective channels.

Performance Improvement in Spatially Multiplexed MIMO Systems over Weibull-Gamma Fading Channel

AbstractIn multiple-input multiple-output (MIMO) systems, spatial demultiplexing at the receiver has its own significance. Thus, several detection techniques have been investigated. There is a tradeoff between computational complexity and optimal performance in most of the detection techniques. One of the detection techniques which gives improved performance and acceptable level of complexity is ordered successive interference cancellation (OSIC) with minimum mean square error (MMSE). However, optimal performance can be achieved by maximum likelihood (ML) detection but at a higher complexity level. Therefore, MMSE-OSIC with candidates (OSIC

ASEP of MIMO System with MMSE-OSIC Detection over Weibull-Gamma Fading Channel Subject to AWGGN

Ordered successive interference cancellation (OSIC) is adopted with minimum mean square error (MMSE) detection to enhance the multiple-input multiple-output (MIMO) system performance. The optimum detection technique improves the error rate performance but increases system complexity. Therefore, MMSE-OSIC detection is used which reduces error rate compared to traditional MMSE with low complexity. The system performance is analyzed in composite fading environment that includes multipath and shadowing effects known as Weibull-Gamma (WG) fading. Along with the composite fading, a generalized noise that is additive white generalized Gaussian noise (AWGGN) is considered to show the impact of wireless scenario. This noise model includes various forms of noise as special cases such as impulsive, Gamma, Laplacian, Gaussian, and uniform. Consequently, generalizedQ-function is used to model noise. The average symbol error probability (ASEP) of MIMO system is computed for 16-quadrature amplitude modulation (16-QAM) using MMSE-OSIC detection in WG fading perturbed by AWGGN. Analytical expressions are given in terms of Fox-H function (FHF). These expressions demonstrate the best fit to simulation results.

A Performance Comparison of Spatial Multiplexing MIMO Detectors

Many techniques are used in MIMO for various purposes, such as SM (spatial multiplexing), SD (spatial diversity) and antenna beam forming. Among them spatial multiplexing is used in MIMO for accommodating high data-rates applications. In, SM, independent information sequences called as layers are simultaneously transmitted from independent antennas. So, the overall bit-rate compared to single antenna system is thus largely enhanced without requiring extra bandwidth or extra transmission power. However during transmission through channel, individual layers are overlying with each other and MSI (multi stream interference) will occurs at the receiver. So, it is very difficult to obtain intended symbol from the bunch of streams. To solve out this problem of MSI various approaches have been proposed, which provides efficient approximate solution of the detection problem at receiver. Such as zero forcing (ZF), minimum mean square error (MMSE), successive interference cancellation (SIC), Ordered successive interference cancellation (OSIC). In this paper error performance of these SM detection schemes are investigated. They are compared on the basis of their BER performance. General Terms Spatial Multiplexing, MIMO Detectors