Multi-user MIMO

About: Multi-user MIMO is a research topic. Over the lifetime, 10265 publications have been published within this topic receiving 227206 citations. The topic is also known as: multi user mimo & MU-MIMO.

MIMO PLC: Theory, measurements and system setup

Abstract: Inhome Power Line Communications (PLC) enables new and highly convenient networking functions without any additional wires to mains-powered devices. Multiple Input Multiple Output (MIMO) methods significantly improve the coverage of guaranteed data throughputs in private homes. This paper gives an overview on MIMO PLC. The results from the channel measurements motivate to implement a MIMO PLC feasibility study in hardware. The system demonstrates HD video streaming over a 2×4 MIMO channel using Beamforming. A MIMO artificial mains network allows testing of the system in the laboratory.

Small Cell Cluster-Based Resource Allocation for Wireless Backhaul in Two-Tier Heterogeneous Networks With Massive MIMO

Abstract: In this paper, we investigate the resource allocation problem in two-tier heterogenous networks (HetNets) with massive MIMO, where two frequency bands, cellular frequency band and millimeter wave frequency band, are used for wireless backhaul links. To coordinate the interference among small cells (SCs), SCs are grouped into multiple SC clusters (SCCs), where SC users are jointly served by SC base stations (BSs) (SBSs) belonging to the same SCC. To eliminate the multi-user and inter-tier interference, we propose a block diagonalization based precoding scheme at macro-BS and each SCC, where the transmit precoding matrix for users is projected onto the null space of interference channels. Following this, we formulate a power allocation optimization problem to maximize the downlink sum rate of the system subject to per-SCC power and users’ quality of service requirements. Since the formulated problem is nonconvex, we transform it into a convex one by appropriate approximation, and a constrained concave convex procedure based iterative algorithm is proposed to obtain the solution. Furthermore, we prove that the obtained solution converges to the local optimum. Meanwhile, according to the structure of the original formulated problem, we divide it into multiple subproblems and propose an optimal iterative water-filling algorithm. Next, we extend the original problem with per-SBS power constraint, which results in that the precoding of each SCC has to be redesigned. On this basis, we propose an iterative water-filling algorithm to obtain the optimal power allocation and precoding. Numerical results are presented to verify the performance of our proposed algorithms.

Methods and Apparatus for Overlapping MIMO Antenna Physical Sectors

Abstract: Methods and apparatus for positioning antennas of a first wireless cell to form MIMO physical sectors and MIMO virtual sectors. Selecting a MIMO virtual sector for communication responsive to throughput, data throughput, signal-to-noise ratio, signal error rate, data error rate, retransmission requests, interference, rejection of multipath signals, transmission rate, and signal strength.

Multi-service multi-carrier broadband MIMO distributed antenna systems for in-building optical wireless access

Abstract: A novel broad spectrum band-shifting technique is experimentally demonstrated to simultaneously transmit broadband (500MHz to 3 GHz) multi-service, multi-carrier MIMO signals for in-building radio-over-fiber based wireless distributed antenna systems. The proposed scheme uses fewer local oscillators and does not require any service-specific narrowband band pass filters, thus upgrading of existing non-MIMO services to MIMO services or adding new MIMO services would be easier and cost-effective.

Interference Alignment for Partially Connected Downlink MIMO Heterogeneous Networks

Abstract: In this paper, we propose interference alignment (IA) schemes for downlink multiple-input-multiple-output heterogeneous networks (HetNets) with partial connectivity, which is induced by the path loss and the low transmission power of small cells. Specifically, we consider two partially connected scenarios of HetNets. In the first scenario, we focus on the partial connectivity among small cells, whereas in the second scenario, we further consider the partial connectivity between the macrocell and small cells. For the first scenario, we first propose a two-stage IA scheme by exploiting the heterogeneity and partial connectivity of HetNets. Then, the influence of the number of served macro users on system degrees of freedom (DoFs) is investigated. In particular, we derive the condition under which serving one macro user achieves more DoFs than serving multiple macro users and design an algorithm to find the optimal number of served macro users to maximize the system DoFs. Afterward, we study the second scenario and extend the two-stage IA to this scenario. The simulation results show that the proposed IA schemes can significantly improve the system sum rate. Moreover, by considering the partial connectivity between the macro cell and small cells, the system performance can be further improved.