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.

Support for multiple access point switched beam antennas

Abstract: A plurality of virtual wireless networks are defined. Each of the plurality of virtual wireless networks has a different set of requirements. A node is capable of producing a plurality of antenna beams or patterns. Each virtual wireless network is associated with a unique group of the antenna beams or patterns. Users of each of the virtual wireless networks communicate using the antenna beams or patterns associated with that virtual wireless network.

ADMM-based infinity norm detection for large MU-MIMO: Algorithm and VLSI architecture

Abstract: We propose a novel data detection algorithm and a corresponding VLSI design for large multi-user (MU) multiple-input multiple-output (MIMO) wireless receiver. Our algorithm, referred to as ADMIN, performs alternating direction method of multipliers (ADMM)-based infinity norm constrained equalization. ADMIN is an iterative algorithm that outperforms linear detectors if the number of users is small compared to that of the antennas in base station (BS). ADMIN computes the linear minimum mean-square error (MMSE) solution in the first iteration. It is sufficient when the ratio between the numbers of BS antennas and users is rather large. We develop a time-shared and iterative VLSI architecture for LDL-decomposition based soft-output ADMIN. Our architecture achieves 685.71 Mb/s for linear MMSE and 212.38 Mb/s for ADMIN for a 16-user system that employs 64-QAM in a 28 nm CMOS technology.

Multiple user mimo interference suppression communications system and methods

Abstract: Systems and methods for providing an efficient mechanism for transmitting interference vectors to communications terminals, such as user equipments (UEs), in an over the air radio telecommunications network with spatially multiplexed multiple user multiple input multiple output (MU-MIMO) capability. A new pre-coding information downlink channel is defined. Messages containing semi-persistent interference vector information for MU-MIMO user equipment are defined and transmitted over the new channel in a manner that allows infrequent transmission and efficient use of resources. Using the interference vectors and applying inter- user interference adaptation to received messages, the UEs may receive spatially multiplexed MIMO transmissions and actively remove inter-user interference after reception of the messages. Compression of the pre-coding vector information transmitted over the pre-coding information channel may result in additional increases in efficiency in the system.

Practical Known-Plaintext Attacks against Physical Layer Security in Wireless MIMO Systems

Abstract: Physical layer security schemes for wireless communication systems have been broadly studied from an information theory point of view. In contrast, there is a dearth of attack methodologies to analyze the achievable security on the physical layer. To address this issue, we develop a novel attack model for physical layer security schemes, which is the equivalent to known-plaintext attacks in cryptoanalysis. In particular, we concentrate on analyzing the security of orthogonal blinding schemes that disturb an eavesdropper’s signal reception using artificial noise transmission. We discuss the theory underlying our attack methodology and develop an adaptive filter trained by known-plaintext symbols to degrade the secrecy of orthogonal blinding. By means of simulation and measurements on real wireless channels using software-defined radios with OFDM transceivers, we obtain the operating area of our attack and evaluate the achievable secrecy degradation. We are able to reduce the secrecy of orthogonal blinding schemes to Symbol Error Rates (SERs) below 10% at an eavesdropper, with a knowledge of only a 3% of the symbols transmitted in typical WLAN frames.

Link Adaptation for MIMO OFDM Visible Light Communication Systems

Abstract: In this paper, we investigate link adaptation for an orthogonal frequency division multiplexing (OFDM)-based multiple-input multiple-output (MIMO) visible light communication (VLC) system. The proposed adaptive OFDM VLC system supports both repetition coding (RC) and spatial multiplexing (SM) as MIMO modes and allows spatial mode switching based on channel conditions. Regarding to the instantaneous signal-to-noise ratio for both RC and SM modes, the maximum constellation size that can be supported for each MIMO mode on each subcarrier is determined. The MIMO mode that gives the highest spectral efficiency (SE) is then selected. The proposed joint MIMO mode selection and bit loading scheme maximizes the SE while satisfying a target bit error rate. Our numerical results reveal that a peak data rate up to 18.3 Gb/sec can be achieved in a $16 \times 16$ MIMO setting using light emitting diodes with cut-off frequency of 10 MHz in typical indoor environments.