Multiple-input Multiple-output Detection Scheme Research Articles

Reconfigurable design of hybrid MIMO detection scheme for spatially multiplexed MIMO system

In recent years, Multiple Input–Multiple Output (MIMO) has been used to expand data transfer for ensuring consistency. The transmitter and receiver use several antennas and they can achieve high spectral characteristics. The numbers of users and antennas increase rapidly questions the stability and reliability of the system. When MIMO is deployed, the complexity of the system increases and it becomes a major problem in many detection systems. When more and more number of receiver and senders pre-require an increased number of hardware components and a part it further increases the system's complexity and design. It is important to develop sophisticated components to improve compliance with many standards without compromising the Bit Error Rate (BER) performance of the components. The proposed work introduces a New Hybrid MIMO Detector (NHMD), which provides the solution for the complicated design procedure. The core concentration of this work is to minimize the complexity (Hardware) of the system by applying simplest design approach. This Hybrid system with a minimalistic detection approach helps in improve the BER: (Bit Error Rate) of the framework without compromising the overall performance of the system. This proposed method is designed on the Modified Optimal Differential Evolution (MODE) algorithm which is used to apt the best detector by deploying the objectives of this work. In addition, this method uses parallel processing to reduce the amount of arithmetic logic. The proposed NHMD method is implemented for cylindrical devices belonging to different FPGA families with different antenna configurations (2 × 2, 4 × 4). The proposed NHMD method provides superior quality by combining multiple detectors. The simulation results confirm that the NHMD method uses low equipment as well as low power consumption and provides high efficiency without affecting BER performance.

An Improved Expectation Propagation Based Detection Scheme for MIMO Systems

Multiple-input Multiple-output (MIMO) technologies play an important role in modern and future wireless communication systems as they can improve the capacity without increasing the bandwidth. MIMO detection is one of the key technologies for MIMO system designs. MIMO detection schemes based on Message Passing (MP) algorithms have attracted extensive attention in recent years. The MIMO detection scheme based on Expectation Propagation (EP), which is also a kind of MP algorithms, has been proved to achieve the Bayes-optimal performance under the conditions of large system limit and compression rate threshold. However, there is improvement space for the detection performance of the EP algorithm when the conditions are not satisfied, which are the common cases in the practical applications. In this paper, when the conditions of the large system limit and compression rate threshold are not satisfied, we analyze the influences of two factors, the initial parameters selection and the moment matching strategy, on the performance of EP based detection scheme. As a result, we propose an improved EP detection scheme based on optimizing the two factors. Simulation results show that the proposed scheme outperforms the original EP detection scheme in different MIMO scenarios.

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.

Iterative Unreplicated Parallel Interference Canceler for MDL-Tolerant Dense SDM (12-Core × 3-Mode) Transmission Over 3000 km

We propose a novel multiple-input multiple-output (MIMO) detection scheme based on iterative unreplicated parallel interference cancelling (UPIC) technique for mode dependent loss (MDL)-impaired few-mode fibre (FMF) transmission. An optical MIMO channel over an FMF exhibits a mode-dependent property where each mode division multiplexed signal is passed through a different lossy channel, known as an MDL phenomena. One challenging issue for realising future deployable space division multiplexing (SDM) systems is establishing reliable and robust signal transmission techniques in the presence of MDL. The main contributions of this paper include first, a proposal of newly developed iterative interference cancellation technique with parallel processing for MDL-impact mitigation, second, a comparative study on performance of MIMO detection schemes, and third, a demonstration of the longest dense SDM transmission over multicore (MC)-FMF. The proposed UPIC with iterative processing is experimentally shown to improve Q-factors by more than 3 dB, and record-long dense SDM transmission reach exceeding 3000 km over 12-core × 3-mode MC-FMF was achieved.

Large MIMO Detection Schemes Based on Channel Puncturing: Performance and Complexity Analysis

A family of low-complexity detection schemes based on channel matrix puncturing targeted for large multiple-input multiple-output (MIMO) systems is proposed. It is well known that the computational cost of MIMO detection based on QR decomposition is directly proportional to the number of non-zero entries involved in back-substitution and slicing operations in the triangularized channel matrix, which can be too high for low-latency applications involving large MIMO dimensions. By systematically puncturing the channel to have a specific structure, it is demonstrated that the detection process can be accelerated by employing standard schemes, such as chase detection, list detection, nulling-and-cancellation detection, and sub-space detection on the transformed matrix. The performance of these schemes is characterized and analyzed mathematically, and bounds on the achievable diversity gain and probability of bit error are derived. Surprisingly, it is shown that puncturing does not negatively impact the receive diversity gain in hard-output detectors. The analysis is extended to soft-output detection when computing per-layer bit log-likelihood ratios; it is shown that significant performance gains are attainable by ordering the layer of interest to be at the root when puncturing the channel. Simulations of coded and uncoded scenarios certify that the proposed schemes scale up efficiently both in the number of antennas and constellation size, as well as in the presence of correlated channels. In particular, soft-output per-layer sub-space detection is shown to achieve a 2.5 dB signal-to-noise ratio gain at 10−4 bit error rate in 256-quadratic-amplitude modulation $16\times 16$ MIMO, while saving 77% of nulling-and-cancellation computations.

Efficient detection in uniform linear and planar arrays MIMO systems under spatial correlated channels

SummaryIn this paper, the efficiency of various multiple‐input multiple‐output (MIMO) detectors was analyzed from the perspective of highly correlated channels, where MIMO systems have a lack of performance, besides in some cases, an increasing complexity. Considering this hard but a useful scenario, various MIMO detection schemes were accurately evaluated concerning complexity and bit error rate performance. Specifically, successive interference cancellation, lattice reduction, and the combination of them were associated with conventional linear MIMO detection techniques. To demonstrate effectiveness, a wide range of the number of antennas and modulation formats have been considered aiming to verify the potential of such MIMO detection techniques according to their performance‐complexity trade‐off. We have also studied the correlation effect when both transmit and receiver sides are equipped with uniform linear array and uniform planar array antenna configurations. The performance of different detectors is carefully compared when both antenna array configurations are deployed considering a different number of antennas and modulation order, especially under near‐massive MIMO condition. We have also discussed the relationship between the array factor and the bit error rate performance of both antenna array structures.

Dual QR decomposition in K-best sphere detection for Internet of Things networks

Internet of Things (IoT) in 5G communications is becoming more popular due to its robust features. Multiple input multiple output (MIMO) in IoT is playing a vital role nowadays with large and massive concepts. At the same time detection in such scenario is becoming complex day by day. Sphere decoding algorithms is one of the MIMO detection schemes used for achieving near-optimal maximum likelihood detection (MLD) performance. Preprocessing algorithms such as lattice reduction and QR-decomposition (QRD) has been widely used along with the variants of MIMO detection for achieving better bit error rate (BER) performance. This research paper proposes a novel dual QRD (DQRD) algorithm to obtain a universal low complex-lattice reduction aided (UL-LRA)—K-best sphere detection (KSD) for MIMO networks. The proposed algorithm is evaluated under additive white Gaussian noise flat fading and indoor task group ac (TGac-channel D) channel model. The results proved that the BER performance was enhanced as well as the average runtime complexity of LRA–KSD was reduced by 45 and 39% in a flat faded and channel D respectively compared to the optimal MLD using 16-QAM.

Spectrally efficient polarization multiplexed direct-detection OFDM system without frequency gap.

We experimentally demonstrate a spectrally efficient direct-detection orthogonal frequency-division multiplexing (DD-OFDM) system. In addition to polarization-division multiplexing, removing the frequency gap further improves the spectral efficiency of the OFDM system. The frequency gap between a reference carrier and OFDM subcarriers avoids subcarrier-to-subcarrier beating interference (SSBI) in traditional DD-OFDM systems. Without dynamic polarization control, the resulting interference after square-law direct detection in the proposed gap-less system is polarization-dependent and composed of linear inter-carrier interference (ICI) and nonlinear SSBI. Thus, this work proposes an iterative multiple-input multiple-output detection scheme to remove the mixed polarization-dependent interference. Compared to the previous scheme, which only removes ICI, the proposed scheme can further eliminate SSBI to achieve the improvement of ∼ 7 dB in signal-to-noise ratio. Without the need for polarization control, we successfully utilize 7-GHz bandwidth to transmit a 39.5-Gbps polarization multiplexed OFDM signal over 100 km.

Performance and Complexity Evaluation of Iterative Receiver for Coded MIMO-OFDM Systems

Multiple-input multiple-output (MIMO) technology in combination with channel coding technique is a promising solution for reliable high data rate transmission in future wireless communication systems. However, these technologies pose significant challenges for the design of an iterative receiver. In this paper, an efficient receiver combining soft-input soft-output (SISO) detection based on low-complexity K-Best (LC-K-Best) decoder with various forward error correction codes, namely, LTE turbo decoder and LDPC decoder, is investigated. We first investigate the convergence behaviors of the iterative MIMO receivers to determine the required inner and outer iterations. Consequently, the performance of LC-K-Best based receiver is evaluated in various LTE channel environments and compared with other MIMO detection schemes. Moreover, the computational complexity of the iterative receiver with different channel coding techniques is evaluated and compared with different modulation orders and coding rates. Simulation results show that LC-K-Best based receiver achieves satisfactory performance-complexity trade-offs.

Multi-User OFDM MIMO in IEEE 802.11ac: A Simulation Framework to Analysis and Synthesis

In this paper a simulation framework to analyze, design and optimize the physical layer of IEEE 802.11ac wireless local networks focusing on multi-user operation scenario is described and validated. The performance of channel inversion, regularized channel inversion and block diagonalization precoding schemes with zero forcing and minimum mean squared error multiple input multiple output (MIMO) detectors is evaluated over different configurations of 802.11 Task Group n (TGn) and TGac channel models. The expressive power loss due to multi-user operation has shown that more advanced precoding and MIMO detection schemes must be designed to allow satisfactory operation into feasible signal-to-noise-ratio ranges.

Efficient list‐sphere detection scheme for joint iterative multiple‐input multiple‐output detection

List-sphere detection (LSD) is a sub-optimal multiple-input multiple-output (MIMO) detection scheme which searches candidate symbol vectors that lie within a sphere of a given radius. This study presents an efficient LSD based method for a joint iterative MIMO detection scheme. The proposed method utilises a channel condition in order to define the list size. During the search process, the radius is adaptively updated to reduce the computational complexity. Owing to the list size and corresponding radius are adaptively determined by the channel condition, the authors can operate the detector at the most appropriate complexity to produce the required performance. Simulation results show that the proposed methods provide substantial complexity reduction without bit error rate performance degradation.

Uplink bit combining for multiple base‐stations MIMO with applications to CoMP systems

AbstractThis work considers a simple bit level combining technique, aided by robust bit reliability information, for uplink collaborating multiple‐input multiple‐output (MIMO) base‐stations (also known as macrodiversity MIMO), operating over composite Rayleigh‐lognormal fading channels. Bit reliability weights based on a robust modification of the logarithmic likelihood ratio, combined with instantaneous symbol signal‐to‐noise ratio information, are derived for different local MIMO detection schemes. This bit reliability information is used at the fusion center, together with locally detected data, for combining and producing final information bits delivered to the destination. Computer simulation results confirm that such bit level combining techniques, when used with minimum mean squared error ordered successive interference cancelation and also with sphere decoding maximum likelihood local detectors, provide significant performance improvements over non‐collaborative base‐stations systems. Performance gains are maintained even when these schemes suffer from channel estimation errors and also in the presence of space correlation. Low backhaul overhead and performance advantages make these bit level combining techniques attractive for applications in next generation cellular systems employing coordinated multi‐point (CoMP) technology, as well as for other collaborative MIMO communication schemes.Copyright © 2014 John Wiley & Sons, Ltd.

LR-Aided MIMO Detectors under Correlated and Imperfectly Estimated Channels

In this contribution, lattice reduction (LR) technique is applied to improve the multiple-input multiple-output (MIMO) detector performance under correlated channels and imperfect channel estimation constrains. Zero-forcing, minimum mean squared error, ordered successive interference cancellation and sphere decoding (SD) detectors are analysed taking into consideration (a) different correlated fading channel indexes, (b) increasing spectral efficiency, by combining number of transmit antennas and modulation formats, and (c) channel coefficient error estimations. Analysis of correlated channel effects over the MIMO system performance equipped with different LR-aided detectors are carried out, indicating the robustness of those detectors and the SD–MIMO detector deficiency to deal with such channel condition. Besides, computational complexities are compared aiming to determine the best LR–MIMO detection scheme under the perspective of performance-complexity tradeoff.

スーパーハイビジョン映像の素材伝送に向けたブロックQR分解を用いた演算量削減型MLD

We have been developing a portable digital transmission system for next generation television called “Super Hi-Vision (SHV)” with hundreds of Mbps-class transmission and high link reliability. To fulfill these requirements, we have been researching a multiple-input multiple-output (MIMO) multiplexing technology using a millimeter-wave (42/55-GHz) band allocated for broadcasting organizations. In this paper, we propose a low-complexity MIMO detection scheme that uses block QR decomposition with M-algorithm to reduce the computational complexity of the maximum likelihood detection (MLD) method. In the proposed algorithm, a MIMO channel is converted into a block upper triangular matrix multiplied by a unitary matrix and divided into some small block matrices. Then, the transmit signals are selected by Manhattan metrics to reduce the complexity, and squared Euclidean metrics of the selected signal candidates are calculated in these block matrices. Computer simulations with a correlated 4 x 4 MIMO channel demonstrate that the proposed scheme shows almost the same BER performance as that of the MLD and better BER performance than that of the conventional QRM-MLD (QR decomposition with M-algorithm MLD) with less complexity.

Reduced Complexity MIMO Detection Scheme Using Statistical Search Space Reduction

The minimum-mean-square-error (MMSE) detection is advantageous in its low-complexity while suffering from severe performance degradation. The post-processing signal-to-interference-and-noise ratio (SINR) distribution of MMSE detector, however, shows the potential of high reliability in the high-SINR detected symbols. We propose a low-complexity multiple-input multiple-output (MIMO) detection scheme by exploiting the MMSE detector concatenated with the sphere decoder (SD), where the MMSE detected symbols above the SINR thresholds are retained as the final decisions and the remaining lower-SINR symbols are to be detected by the SD. By retaining the high-SINR symbols detected in the MMSE, the search space can be significantly reduced without incurring much extra error rate. Simulation results demonstrate that the proposed MMSE-SD detection scheme performs near-optimal performance at much lower computational complexities compared to SD algorithm.

Low complexity lattice reduction scheme for STBC two-user uplink MIMO systems

Abstract Recently, a lattice reduction-aided (LRA) multiple-input multiple-output detection scheme has been proposed in junction with linear (as well as nonlinear) detectors. It is well known that these schemes provide a full diversity, and its complexity is comparable to that of linear detectors for the block fading channels. For the fast varying channels, however, the decoding complexity of LRA detection scheme is unreasonably high. This article proposes an efficient iterative lattice reduction (LR) scheme for an uplink system with two receive antennas at the base station and two users, each employing the Alamouti space-time block code (STBC). By taking advantage of the certain inherent STBC structure of transmitted symbols from users, the proposed scheme provides the same performance as a conventional LR while saving about 80% computational complexity. We also show that it can be successfully extended to handle the scenario where another interfering user, who is also employing the Alamouti STBC, is present.

MIMO Detection Schemes with Interference and Noise Estimation Enhancement

Different detection schemes for multiple-input, multiple-output (MIMO) systems are investigated. By enhancing the interference and noise estimation, we propose a novel MIMO receiver strategy, which is shown to achieve superior performance with moderate increase in computational complexity compared to conventional MIMO detection schemes.

Error Performance of Prerake Diversity Combining-Based UWB Spatial Multiplexing MIMO Systems over Indoor Wireless Channels

In this letter, we consider a novel ultra-wideband (UWB) spatial multiplexing (SM) multiple input multiple output (MIMO) structure, which consists of prerake diversity combiners in the transmitter and a zero forcing (ZF) detector in the receiver. For a UWB SM MIMO system with N transmit antennas, M receive antennas, and L resolvable multipath components, it is shown that the proposed prerake combining-based MIMO detection scheme has the diversity order of (LN - M + 1) and its BER performance is analytically presented in a log-normal fading channel and also compared with that of a rake combining-based ZF scheme.

An Ordered Successive Interference Cancellation Scheme in UWB MIMO Systems

In this letter, an ordered successive interference cancellation (OSIC) scheme is applied for multiple-input multiple-output (MIMO) detection in ultra- wideband (UWB) communication systems. The error rate expression of an OSIC receiver on a log-normal multipath fading channel is theoretically derived in a closed form solution. Its bit error rate performance is analytically compared with that of a zero forcing receiver in the UWB MIMO detection scheme followed by RAKE combining. Performance of the ZF detector is known to be similar to that of the MMSE receiver at high signal-to-noise ratios (SNRs). This work focuses on the analysis of a ZF related scheme. In this letter, we present the error performance of a ZF scheme with an ordered successive interference cancellation (OSIC) for UWB SM MIMO detection in a log-normal fading channel. We analytically investigate the theoretic bit error rate (BER) performance of the ZF-OSIC architecture followed by RAKE combining, called a ZF-OSIC-RAKE, in an UWB SM MIMO receiver. The diversity order that the ZF-OSIC-RAKE offers for detecting the n-th transmitted data stream is obtained for UWB MIMO systems. It is also seen that the ZF-OSIC-RAKE scheme outperforms the ZF-RAKE.

Implementation-friendly QRM-MLD using trellis-structure based on Viterbi algorithm

The maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD) has been presented as a suboptimum multiple-input multiple-output (MIMO) detection scheme which can provide almost the same performance as the optimum maximum likelihood (ML) MIMO detection scheme but with the reduced complexity. However, due to the lack of parallelism and the regularity in the decoding structure, the conventional QRM-MLD which uses the tree-structure still has very high complexity for the very large scale integration (VLSI) implementation. In this paper, we modify the tree-structure of conventional QRM-MLD into trellis-structure in order to obtain high operational parallelism and regularity and then apply the Viterbi algorithm to the QRM-MLD to ease the burden of the VLSI implementation. We show from our selected numerical examples that, by using the QRM-MLD with our proposed trellis-structure, we can reduce the complexity significantly compared to the tree-structure based QRM-MLD while the performance degradation of our proposed scheme is negligible.