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.

Polite water-filling for weighted sum-rate maximization in MIMO B-MAC networks under multiple linear constraints

Abstract: The algorithms in this paper exploit optimal input structure in interference networks and is a major advance from the state-of-the-art. Optimization under multiple linear constraints is important for interference networks with individual power constraints, per-antenna power constraints, and/or interference constraints as in cognitive radios. While for single-user MIMO channel transmitter optimization, no one uses general purpose optimization algorithms such as steepest ascent because water-filling is optimal and much simpler, this is not true for MIMO multiaccess channels (MAC), broadcast channels (BC), and the non-convex optimization of interference networks because the traditional water-filling is far from optimal for networks. We recently found the right form of water-filling, polite water-filling, for some capacity/achievable regions of the general MIMO interference networks, named B-MAC networks, which include BC, MAC, interference channels, X networks, and most practical wireless networks as special cases. In this paper, we use weighted sum-rate maximization under multiple linear constraints in interference tree networks, a natural extension of MAC and BC, as an example to show how to design highly efficiency and low complexity algorithms. Several times faster convergence speed and orders of magnitude higher accuracy than the state-of-the-art are demonstrated by numerical examples.

Multi-Way MIMO Amplify-and-Forward Relay Networks with Zero-Forcing Transmission

Abstract: Two transmission strategies, namely (i) pairwise zero-forcing transmission and (ii) non-pairwise zero-forcing transmission, for multiple-input multiple-output (MIMO) amplify-and-forward (AF) multi-way relay networks (MWRNs) are analytically studied. To this end, lower and upper bounds of the outage probability, the corresponding high signal-to-noise ratio outage probability approximations, the achievable sum rate, and the fundamental diversity-multiplexing trade-off are derived in closed-form. The proposed pairwise zero-forcing transmission strategy possesses a lower practical implementation complexity as each node requires only the instantaneous respective node-to-relay channel knowledge. Counter intuitively, the non-pairwise zero-forcing transmission strategy achieves higher spatial multiplexing gains over the pairwise counterpart at the expense of higher relay processing complexity and more stringent channel state information requirements. Moreover, numerical results are presented to further validate our analysis and thereby to obtain valuable insights into practical MIMO AF MWRN implementation.

A method for transmitting measurement data in a wireless communication system and a wireless communication system

Abstract: The invention relates to a method in a wireless communication system (1) which comprises wireless terminals (MT1-MT4) and at least one access point (AP1, AP2) and access point controller (APC1, APC2). At least one antenna configuration is determined for an antenna (30) of the wireless terminal (MT1-MT4). In the method, the antenna (30) of the wireless terminal (MT1-MT4) is used for receiving a radio signal and the strength of the radio signal received by the antenna (30) of the wireless terminal (MT1-MT4) is measured. A measurement message (HD1, D1) is formed of one or more measurements, which is transmitted from the wireless terminal (MT1-MT4) to the access point (AP1, AP2). Further in the method, data (UAC) about the antenna configuration during the measurement is added into said measurement message (HD1, D1).

Downlink mimo transmission control method and base station apparatus

Abstract: A method of controlling downlink transmission from a base station having multiple antennas to a mobile station having multiple antennas includes the steps of applying open loop-type MIMO diversity to one or more common control channels, an MBMS channel, and an L1/L2 control channel; and applying closed loop-type MIMO multiplexing and/or MIMO diversity to a shared data channel.

Optimal time allocation for dynamic-TDMA-based wireless powered communication networks

Abstract: In this paper, we consider a wireless communication network with a hybrid access point (HAP) and a set of wireless users with energy harvesting capabilities. The HAP is assumed to have two antennas: one for transferring wireless energy in the downlink and one for receiving wireless information in the uplink. Without fixed energy sources, users first have to harvest energy from the wireless signals broadcast by the HAP, and then using the harvested energy to transmit their individual information to the HAP through dynamic-time-division-multiple-access (D-TDMA). We investigate the optimal time allocation to maximize the throughput of the proposed system subject to a total time constant. The formulated throughput maximization problem is proved to be a convex optimization problem. By using convex optimization techniques, the optimal time allocation strategy is obtained in closed-form expression. We show that the optimal time allocation can be obtained with linear complexity. It is then shown by simulations that the total throughput of the network increases with the number of users. It is also shown by simulations that the users with low SNR should be scheduled to transmit first.