Partial Interference Cancellation Research Articles

Beamforming Design With Partial Group Successive Interference Cancellation for ISAC Systems

Beamforming Design With Partial Group Successive Interference Cancellation for ISAC Systems

Partial Tree Search Assisted Symbol Detection for Massive MIMO Systems

In the era of the fifth generation (5G) communication networks, massive multiple-input multiple-output (MIMO) systems demand even lower computation complexity and power consumption while catching up with good detection performance. In this paper, a low-complexity nonlinear detection algorithm is proposed for massive MIMO systems, which is based on partial tree search and successive interference cancellation (SIC). The proposed scheme allows us to expedite the detection process by coping with the transmit symbols group by group. As compared to vertical-Bell laboratories layered space time (V-BLAST), the major breakthrough of computation reduction lies in the fact that the partial tree search can assist the detection process to avoid the inversion of the detection matrix required in each recursion of the SIC process. Both computational complexity analysis and simulation results show that our proposed algorithm not only significantly reduces computational complexity, but also has better bit error rate (BER) performance.

Signal detection algorithms for single carrier generalized spatial modulation in doubly selective channels

This paper is concerned with signal detection for zero-padded single carrier generalized spatial modulation (SC-GSM) in doubly selective channels (DSCs). Novel detection methods are proposed by expressing the DSC in terms of the basis expansion model (BEM) and considering a BEM-based maximum likelihood (BML) framework. The proposed methods, which aim at reducing the complexity of the BML detector, can be divided into two main categories. The methods in the first category, namely BEM-based partial interference cancellation (BPIC) and BPIC with successive interference cancellation (BPIC-SIC), are designed to remove the interference between the signals. Since the satisfactory performance of these methods depend on meeting a constraint on the number of transmit and receive antennas, a second category of methods is proposed, consisting of BEM-based tree search (BTS), BEM-based reduced complexity tree search (BRCTS), and BRCTS with sphere decoding (BRCTS-SD). These methods are developed to overcome the limitations of BPIC and BPIC-SIC while further reducing the detection complexity by shrinking the search space. The performance evaluation of the proposed SC-GSM methods, in terms of computational complexity and bit error rate (BER) over simulated DSCs, underlines their relative merits and clearly demonstrates their advantages over previous methods.

A Seysen's algorithm–based incremental lattice reduction

AbstractLattice reduction (LR)–aided detections have attracted great attention in the symbol detection of multiple‐input–multiple‐output communication, especially for systems with larger scale antennas. Recently, the Lenstra‐Lenstra‐Lovász (LLL)–based incremental LR (ILR) algorithms have been proposed to employ an early termination to jointly conduct the LR and retrieve the symbol based on a partial successive interference cancellation (SIC) detection, which induces a significant performance improvement. In this paper, we propose to apply the Seysen's algorithm (SA) to the ILR. After providing the feasibility analysis, two novel SA involved algorithms are introduced and studied. In particular, a new sorted QR decomposition‐based SA algorithm is proposed and tested as it plays a key role in the SIC detection. Subsequently, a novel SA‐based ILR scheme is further developed and investigated. By simulations, we show that the proposed approach outperforms conventional LLL‐based ILR in various aspects, while only a marginal increment in the complexity, restricted to medium signal‐to‐noise‐ratio regions, is observed.

On the Achievable Rates of Virtual Full-Duplex Relay Channel

We study a multihop “virtual” full-duplex relay channel as a special case of a general multiple multicast relay network. For such a channel, quantize-map-and-forward (QMF) [and its generalization of noisy network coding (NNC) and short message NNC] achieves the cut-set upper bound within a constant additive gap, where the gap grows linearly with the number of relay stages K. This gap, however, may not be acceptable for practical communication systems with multihop transmissions (e.g., a wireless backhaul operating at high frequencies). Recently, we improved the capacity scaling by using a forward sliding-window (SW) decoding and by optimizing the quantization level at each relay, obtaining the gap that grows logarithmically as log K. Furthermore, the improved scheme has lower decoding complexity and delay than the general QMF and NNC approaches. In this paper, we further improve the performance by presenting a mixed scheme in which each relay can perform either decode-and-forward (DF) or the improved QMF (with SW decoding) and can choose to perform rate-splitting to enable partial interference cancellation. In general, the optimization of the relay DF/QMF configuration is combinatorial. Nevertheless, we provide that a simple greedy algorithm finds an optimal configuration under some practically reasonable assumptions. We derive an achievable rate that is easily computable and show that the proposed mixed scheme outperforms the QMF-only schemes. We demonstrate that the performance improvement increases with K, which indicates that the mixed scheme is indeed beneficial for multihop transmission.

Transmit Antenna Subset Selection for Single and Multiuser Spatial Modulation Systems Operating in Frequency Selective Channels

The extensive study of transmit antenna (TA) subset selection (TAS) in the context of spatial modulation (SM) has recently revealed that significant performance gains are attainable compared to SM systems operating without TAS. However, the existing TAS techniques conceived for SM were studied by considering a frequency-flat channel, which does not represent practical frequency-selective channels. In this paper, we address this open problem by designing TAS schemes for zero-padded single-carrier SM systems. Specifically, we employ a partial successive interference cancellation (SIC) receiver and invoke Euclidean distance based TA subset selection (ED-TAS) for each of the subchannels. Furthermore, we show using a theoretical analysis that the parallel subchannels obtained are nearly identical, which enables us to employ majority logic decision to obtain a single TA subset to be used in all the subchannels. The computational burden is additionally reduced by restricting the number of subchannels over which the ED-TAS technique is invoked. Furthermore, the proposed TAS schemes are extended to the multiuser scenario. The theoretical insights developed are validated using simulation results. Specifically, a signal-to-noise ratio gain as high as 3 dB is observed in the single user scenario and about 1 dB in case of a two-user scenario upon employing our TAS.

Successive Partial Interference Cancellation Scheme for FD-MIMO Relaying

Successive Partial Interference Cancellation Scheme for FD-MIMO Relaying

Partial interference cancellation with maximum likelihood sequence detection in FBMC spatial multiplexing system

Intrinsic interference in filter bank multicarrier (FBMC) modulation prevents the maximum likelihood (ML) detection in spatial multiplexing (SM) system. This intrinsic interference is caused by the transmultiplexer impulse response in time-frequency domain. Solutions based on interference cancellation are not always effective because they may introduce error propagation. In this paper, we propose to study some receivers based on reducing the interference concerned by the cancellation. These solutions can be seen as a trade-off between the whole Viterbi (ML) detection and the whole interference cancellation. The principle of the proposed receivers is to partially estimate and cancel the interference, and the rest of the interference is processed by a low complexity Viterbi detector. We show in this work that the receiver performance depends on the transmultiplexer impulse response and on the choice of the partial Viterbi detector.

Full-Duplex Decode-and-Forward Relay-Assisted Interference Management: A Diversity Gain Region Perspective

A two-user Z-channel with a full-duplex (FD) decode-and-forward (DF) relay, where one user is interference-limited while the other user is interference-free, is considered in this paper. The FD-DF relay can decode either a part of the interference or the entire interference. The former is called partial DF (PDF) protocol, and the latter is called complete DF (CDF) protocol. In the case of PDF protocol, the interference-limited user does partial interference cancellation. A closed-form expression for achievable diversity gain region (DGR) with the PDF protocol is presented. Furthermore, achievable DGR of the PDF protocol is optimized under the constraint that the interference-free receiver achieves optimal diversity gain. At low interference levels, the PDF protocol provides better DGR compared to both CDF protocol and direct transmission scheme. As the interference level increases, either the CDF protocol or the direct transmission scheme is shown to achieve better DGR compared to PDF protocol. The multiplexing gain regions where the PDF, CDF, and direct transmission schemes perform well are identified.

On Dynamic Time-Division-Duplex Transmissions for Small-Cell Networks

Motivated by the promising benefits of dynamic Time Division Duplex (TDD), in this paper, we use a unified framework to investigate both the technical issues of applying dynamic TDD in homogeneous small cell networks (HomSCNs), and the feasibility of introducing dynamic TDD into heterogeneous networks (HetNets). First, HomSCNs are analyzed, and a small cell BS scheduler that dynamically and independently schedules DL and UL subframes is presented, such that load balancing between the DL and the UL traffic can be achieved. Moreover, the effectiveness of various inter-link interference mitigation (ILIM) schemes as well as their combinations, is systematically investigated and compared. Besides, the interesting possibility of partial interference cancellation (IC) is also explored. Second,based on the proposed schemes, the joint operation of dynamic TDD together with cell range expansion (CRE) and almost blank subframe (ABS) in HetNets is studied. In this regard, scheduling polices in small cells and an algorithm to derive the appropriate macrocell traffic off-load and ABS duty cycle under dynamic TDD operation are proposed. Moreover, the full IC and the partial IC schemes are investigated for dynamic TDD in HetNets. The user equipment (UE) packet throughput performance of the proposed/discussed schemes is benchmarked using system-level simulations.

A Low-Complexity Detection Scheme for Generalized Spatial Modulation Aided Single Carrier Systems

Generalized spatial modulation (GSM), which combines spatial modulation (SM) and vertical Bell Laboratories layered space-time (V-BLAST), is a novel attractive multi-input multi-output (MIMO) technique. In this letter, a low-complexity near-optimal detection scheme is presented for GSM aided single carrier (SC) transmission over dispersive channels. Compared to the conventional partial interference cancellation receiver with successive interference cancellation (PIC-R-SIC), the proposed scheme offers a near maximum likelihood (ML) detection performance while avoiding complicated matrix operations, which allows it to exhibit a lower computational complexity. Simulation results show that the proposed scheme provides a considerable performance improvement compared to PIC-R-SIC, especially in rank-deficient channels scenarios.

Partial Inter-Relay Interference Cancellation in Two Path Successive Relay Network

This letter proposes a partial interference cancellation scheme to cancel the inter-relay interference (IRI) in two path successive relay (TPSR) network, where part of the IRI signals are retained at the destination node during the decoding process to improve the performance. Besides, to reduce the decoding complexity of the proposed scheme, the iteration maximal ratio combining (I-MRC) decoding algorithm is designed. Then, we analyse the diversity gain of the proposed scheme. The analysis and simulation results show that the proposed partial IRI cancellation scheme can improve the performance of the TPSR network and obtain extra diversity gain.

Alamouti Coded Blind Interference Alignment with Partial Interference Cancellation Group Decoding

Interference alignment is a promising technique which suppresses interference in multiuser wireless networks. Most research on interference alignment aims at deriving or realizing the maximum achievable Degrees of Freedom (DoF), as well as the diversity gain is usually one. However, achieving better diversity performance is equally important. To improve the diversity gain, this paper presents an Alamouti coded Blind Interference Alignment (BIA) scheme, which combines interference alignment with Alamouti coding. First, the Alamouti coded BIA scheme for a two-user MIMO X channel is proposed. The proposed scheme results in 4/3 DoF with no channel state information at transmitters, and an equivalent channel matrix with partly orthogonal columns. The orthogonal structure can be exploited to obtain diversity gain. Therefore, we then explore the Partial Interference Cancellation (PIC) group decoding and ZF algorithm. Simulation results show that the proposed scheme achieves a higher diversity gain of 2, while keeps the same DoF as the original BIA scheme.

A Reduced-Complexity Partial-Interference-Cancellation Group Decoder for STBCs

In this letter, we propose a reduced-complexity implementation of partial interference cancellation group decoder with successive interference cancellation (PIC-GD-SIC) by employing the theory of displacement structures. The proposed algorithm exploits the block-Toeplitz structure of the effective matrix and chooses an ordering of the groups such that the zero-forcing matrices associated with the various groups are obtained through Schur recursions without any approximations. We show using an example that the proposed implementation offers a significantly reduced computational complexity compared to the direct approach without any loss in performance.

Space-Frequency Codes for MIMO-OFDM Systems with Partial Interference Cancellation Group Decoding

Partial interference cancellation (PIC) group decoding is an attractive decoding alternative for multiple-input multiple-output (MIMO) wireless communications. It can well deal with the tradeoff among rate, diversity and decoding complexity of space-time block codes. In this paper, a design criterion of full-diversity space-frequency codes (SFC) is proposed for MIMO-OFDM systems with the PIC group decoding. Based on the criterion, a systematic design of full-diversity SFC is proposed that can achieve full diversity under the PIC group decoding. Simulation results of the newly proposed codes demonstrate the theory.

Spatial Modulation Aided Zero-Padded Single Carrier Transmission for Dispersive Channels

In this paper, we consider spatial modulation (SM) operating in a frequency-selective single-carrier (SC) communication scenario and propose zero-padding instead of the cyclic-prefix considered in the existing literature. We show that the zero-padded single-carrier (ZP-SC) SM system offers full multipath diversity under maximum-likelihood (ML) detection, unlike the cyclic-prefix based SM system. Furthermore, we show that the order of ML detection complexity in our proposed ZP-SC SM system is independent of the frame length and depends only on the number of multipath links between the transmitter and the receiver. Thus, we show that the zero-padding applied in the SC SM system has two advantages over the cyclic prefix: 1) achieves full multipath diversity, and 2) imposes a relatively low ML detection complexity. Furthermore, we extend the partial interference cancellation receiver (PIC-R) proposed by Guo and Xia for the detection of space-time block codes (STBCs) in order to convert the ZP-SC system into a set of narrowband subsystems experiencing flat-fading. We show that full rank STBC transmissions over these subsystems achieves full transmit, receive as well as multipath diversity for the PIC-R. Furthermore, we show that the ZP-SC SM system achieves receive and multipath diversity for the PIC-R at a detection complexity order which is the same as that of the SM system in flat-fading scenario. Our simulation results demonstrate that the symbol error ratio performance of the proposed linear receiver for the ZP-SC SM system is significantly better than that of the SM in cyclic prefix based orthogonal frequency division multiplexing as well as of the SM in the cyclic-prefixed and zero-padded single carrier systems relying on zero-forcing/minimum mean-squared error equalizer based receivers.

On high-rate full-diversity space-time-frequency code with partial interference cancelation group decoding for frequency-selective channels

An explicit design of a linear dispersive space-time-frequency (STF) code is investigated with a design criterion achieving a high rate for frequency-selective channels when the partial interference cancelation (PIC) group decoding is implemented at receiver. With an appropriate grouping scheme, the proposed STF code is shown to obtain a similar diversity gain as that of the maximum likelihood (ML) decoding, namely the full-dimensional sphere decoding, but with a low complexity. It seems as an intermediate decoding approach between the ML decoding and the zero-forcing (ZF) decoding. The present grouping design criterion for the PIC group decoding that provides full diversity with orthogonal-frequency-division multiplexing (OFDM) is also an intermediate condition between the loosest ML full rank criterion of codewords and the strongest ZF linear independence of column vectors of the equivalent frequency-selective channel matrix. Simulation results show that the proposed PIC group decoding scheme can well address the rate-performance-complexity tradeoff of the multiple-input multiple-output orthogonal-frequency-division multiplexing (MIMO-OFDM) wireless communication system.

주파수 비선택적 SIMO 페이딩 채널에서 단일 송신 안테나 및 시간 다이버시티를 이용한 두 사용자의 동시 전송 기법

A dual-user multiplexing scheme for a pair of mobiles equipped with single antenna is proposed which incorporates time-delay diversity employing a rotation-based D-BLAST-like layered code. A low-dimension equivalent of the existing partial interference cancellation based group decoder is also proposed for the corresponding receiver. The BER performances of the proposed scheme and those of the ideal scheme are studied comparatively through Monte Carlo simulations.

PIC 그룹 복호화를 이용한 최적화된 Double-ABBA 유사 직교 시공간 부호

본 논문에서는 그룹(group)을 2개의 심볼(symbol)로 나누는 시스템을 제안하는데, 이 두 개의 더해진 심볼들은 다중화에 의해 분리된 후 역다중화 기술을 이용해 다시 합해진다. 제안된 시스템에서 간단한 PIC(Partial Interference Cancelation) 그룹 복호화 기술은 Double-ABBA(D-ABBA) 유사 직교(Quasi-Orthogonal) 시공간 부호(Space Time Code)를 위해 사용된다. 이 부호는 고차 MIMO(Multiple Input Multiple Output) 시공간 블록 부호화에서 복호화시에 복잡도를 줄여준다. 그리고 기존의 방법과 제안된 방법과의 성능을 비교한다.

An Enhanced Channel Estimation with Partial Interference Cancelation for MU-MIMO System

In this letter, we propose an enhanced channel estimation method for multi-user multiple-input multiple output (MU-MIMO) transmission in long term evolution (LTE)-Advanced system. The proposed method partially estimates and eliminates the interference using simple matrix operations. After that, we apply an iterative channel estimation scheme. Due to the improvement of initial channel estimation performance, the proposed channel estimation method has significantly large performance gain compared to conventional method.