In this paper, we investigate the performance of the spatial-temporal zero-forcing linear equalizer architectures for a single-carrier Massive MIMO uplink system under frequency-selective fading environment. We establish relationships between the choosing equalizer length $D$ and the system performance in terms of system degrees of freedom and signal-to-interference plus noise ratio (SINR). We also present how system parameters (number of antennas $M$ and the transmit signal-to-noise ratio) impact the system performance differently for both single-cell systems and multi-cell systems with perfect and imperfect channel state information. Furthermore, we show that the probability density function (PDF) of the SINR can be accurately approximated as a Gamma distribution by using the moment matching method. Then, closed-form expressions of the ergodic rate and the outage probability are derived based on the PDF of the SINR.

Performance of ZF Linear Equalizers for Single Carrier Massive MIMO Uplink Systems

According to one embodiment there is provided a method of determining receiver beam forming vectors for a plurality of receivers in a MIMO system. Each receiver comprises a plurality of receiver antennae. The MIMO system also comprises a plurality of transmitter antennae. The method comprises quantifying the properties of the channels of the MIMO system in a channel property matrix including interference between individual channels and performing Cholesky decomposition of the receiver property matrix row-by-row into a lower triangular matrix with unit elements along its diagonal, a diagonal matrix and the Hermitian transpose of said triangular matrix. Performing the Cholesky decomposition comprises determining, when performing a step of the Cholesky decomposition for a row, a receiver-beam forming vector associated with the row that maximises the component of the diagonal matrix in the row.

Method and apparatus for determining receiver beam forming vectors in multi-user MIMO systems

A wireless communication system in which non-linear pre-coding is performed, wherein degradation in transmission characteristics caused by feedback error is ameliorated. This terminal device receives a non-linearly pre-coded and spatially multiplexed wireless signal from a base station device provided with a plurality of antennas, the terminal device being provided with a propagation path estimator (53) for estimating information regarding the propagation path between the terminal device and the base station device, a terminal antenna unit (51) for acquiring a linear filter calculated by the base station device, and a channel equalizer (57) for subjecting the wireless signal received at a first moment in time to a channel equalization process on the basis of the linear filter and the propagation path information at a second moment in time further in the past than the first moment in time.

Terminal device, base station device, wireless communication system, reception method, and integrated circuit

Massive Multiple-Input-Multiple-Output (MIMO) has been outlined as one of the main technologies for achieving the potential in future communication networks. Its theoretical conception was approximately seven years ago, and since then, research activity has grown exponentially [1]. For this research to be commercialized, it is critical to find out how reality differs from theoretical results. This has now become possible with National Instruments’ new Massive MIMO Application Framework, which aims at enabling researchers to rapidly prototype theoretical results in a practical scenario. This thesis aims at using said application framework to understand the implications of using Massive MIMO in wireless sensor networks through a specific scenario called Decision Fusion, where the main principle is to combine data from multiple information sources to take a global decision about a physical event. In this case, the information sources are sensors measuring frequency spectrum activity, and the global decision is whether the spectrum is in use by other mobile units. This work has produced an experiment model and real-world channel measurements that are in the process of being analyzed. The report outlines strengths and weaknesses of the model and suggests possible future work. All implementation files are in the attached folder.

Experimental Analysis for Next-Generation Wireless Sensor Networks

Enabling Massive Device Connectivity in 5G Cellular Networks

In this paper, we propose a novel method of Cholesky factorization based on the minimum mean square error (MMSE) criterion for Tomlinson-Harashima Precoding (THP), which is applied to the downlink of multiuser multiple-input multiple-output (MU-MIMO) system with single mobile antenna equipped for each user. The proposed scheme is also applicable to the MU-MIMO system with multiple mobile antennas for each user. Our proposed de-composition method for THP with MMSE criterion provides a clear theoretical basis and we have compared it with the existing Block Diagonalization (BD) and Dirty Paper Coding (DPC) schemes. As a result, the BER characteristics among BD, THP with MMSE and DPC have been clarified.

Comparative study for Tomlinson -Harashima Precoding based on MMSE criteria in multiuser MIMO downlink system

Single-Carrier (SC) transmission with the same bandwidth as Multi-Carrier (MC) transmission (such as OFDM) may have far shorter symbol duration and is considered to be more robust against time selective fading. In this paper, we proposed the novel equalization and signal separation schemes in time domain for short block length transmission, i.e., Block Linear Equalization (BLE) and Block Nonlinear Equalization (BNLE) on MIMO frequency selective fading channels. The proposed BLE uses the MMSE based inverse matrix in time domain and the BNLE utilizes the QRD-M (QR Decomposition with M algorithm) with appropriate receiver complexity. We compared the computational complexity among the conventional SC-FDE (Frequency Domain Equalization) scheme and the proposed equalizers. We also used the Low-Density Parity Check (LDPC) decoder concatenated to the proposed BLE and BNLE.

/pdf/linear-and-nonlinear-time-domain-block-equalizers-on-mimo-2w7wkma2n5.pdf

Linear and Nonlinear Time Domain Block Equalizers on MIMO Frequency Selective Channels

In this paper, we focus on the cancellation of the interferences among Destination Users (DU's) in the nonregenerative Multiuser Multiple-Input Multiple-Output (MU-MIMO) downlink relay system. By the comparison with Block Diagonalization (BD) and conventional Dirty Paper Coding (DPC) based on LQ Decomposition(LQD), a novel design method of transmit weights for DPC is proposed to successively eliminate the interference among DU's, each of which is equipped with multiple receive antennas. For the proposed schemes, we firstly study the transmit weights design for the conventional Amplify-and-Forward (AF) relay system where the Relay Station (RS) just retransmits the amplified received signals, then we extend it to the joint design of transmit weights both at the Base Station (BS) and the RS, where a DU selection algorithm with low complexity is adopted at the RS to obtain the multiuser diversity. The comparisons of rate performances and BER characteristics between the proposed schemes and the conventional methods verify the effectiveness of the proposed schemes.

Comparative study of transmit weight designs for nonregenerative Multiuser MIMO downlink relay system

Cooperative networking schemes in wireless networks provide cooperative diversity gain using differently located antennas that combat fadings induced by multipath propagation. In this paper, we present the optimal weight design for the destination in AF (Amplify and Forward) relay system, where the optimally designed MRC (Maximum Ratio Combining) is employed at the destination for S→D link (direct link between source and destination) and R→D links (indirect links between relays and destination). We investigate the BER performance of 1S→NR→LD system composed of one source, N relay nodes equipped with single antenna and one destination node equipped with L antennas, which also includes 1S→1R→LD and 1S→NR→1D. Simulation and numerical results are presented to verify our analysis.

Cong Li

Papers

Comparative study for Tomlinson -Harashima Precoding based on MMSE criteria in multiuser MIMO downlink system

Linear and Nonlinear Time Domain Block Equalizers on MIMO Frequency Selective Channels

Comparative study of transmit weight designs for nonregenerative Multiuser MIMO downlink relay system

Performance of AF Relay Networks with Multiple Relays and Multiple Antennas at Destination Using MRC Combining

A study on Dirty Paper Coding with optimal weights in multiuser MIMO downlink