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.

BDMA for Millimeter-Wave/Terahertz Massive MIMO Transmission With Per-Beam Synchronization

Abstract: We propose beam division multiple access (BDMA) with per-beam synchronization (PBS) in time and frequency for wideband massive multiple-input multiple-output (MIMO) transmission over millimeter-wave (mmW)/Terahertz (THz) bands. We first introduce a physically motivated beam domain channel model for massive MIMO and demonstrate that the envelopes of the beam domain channel elements tend to be independent of time and frequency when both the numbers of antennas at base station and user terminals (UTs) tend to infinity. Motivated by the derived beam domain channel properties, we then propose PBS for mmW/THz massive MIMO. We show that both the effective delay and Doppler frequency spreads of wideband massive MIMO channels with PBS are reduced by a factor of the number of UT antennas compared with the conventional synchronization approaches. Subsequently, we apply PBS to BDMA, investigate beam scheduling to maximize the ergodic achievable rates for both uplink and downlink BDMA, and develop a greedy beam scheduling algorithm. Simulation results verify the effectiveness of BDMA with PBS for mmW/THz wideband massive MIMO systems in typical mobility scenarios.

802.11 WLAN: history and new enabling MIMO techniques for next generation standards

Abstract: IEEE 802.11, which designs wireless local area networks (WLAN), is one of the most successful standards in wireless communication systems. In this article, we review the history of WLAN standards, and provide technical overviews of the recent development of WLAN systems. Especially, as the original inventor and the proposer, we focus on beamforming and compressed feedback schemes, which have been adopted in 802.11 WLAN standards, to improve the throughput for a multiple-input multiple-output (MIMO) system. These techniques are essential to maximize the downlink system throughput for multiple user transmission as well as for single user transmission. Also, we present discussions on new technologies to further enhance user throughput, which are currently considered for future WLAN systems.

Full-duplex in large-scale wireless systems

Abstract: In this paper, we investigate the combination of full-duplex wireless communication with large-scale multiple-input multiple-output (MIMO) technology, which has the potential for bidirectional wireless communication at high spectral efficiency and low power consumption. In addition, we study its application to cellular (multi-user) systems that could be extended with large antenna arrays, such as 3GPP LTE. In order to solve the fundamental issue of self-interference cancellation in full-duplex cellular communication systems, we propose two schemes that exploit the excess of antennas present at the base-station (BS) of large-scale MIMO systems. We investigate the associated sum-rate and show that by carefully selecting the ratio between number of transmit and receive antennas at the BS, one is able to maximize the system capacity. We furthermore investigate the inter-user interference issue that occurs in multi-user scenarios, as well as the impact of residual transmit-side (TX) radio-frequency (RF) impairments. Our preliminary results show that large-scale MIMO is able to render full-duplex communication more resilient against inter-user interference and helps to mitigate the effects of residual TX-RF impairments.

Method and apparatus for transmitting multi-user mimo reference signal in wireless communication system for supporting relay

Abstract: A method for transmitting a demodulation reference signal (DMRS) for down-link multi-user MIMO transmission according to an embodiment of the present invention comprises the steps of: mapping a DMRS for a first layer on a down-link physical resource block according to a first DMRS pattern; mapping a DMRS for a second layer on the down-link physical resource block according to a second DMRS pattern; and transmitting the down-link physical resource block. In the down-link physical resource block, a resource element corresponding to the second DMRS pattern can be punctured on the first layer and a resource element corresponding to the first DMRS pattern can be punctured on the first layer and a resource element corresponding to the first DMRS pattern can be punctured on the second layer.

Physical Layer Network Coding with Multiple Antennas

Abstract: The two-phase MIMO NC (network coding) scheme can be used to boost the throughput in a two-way relay channel in which nodes are equipped with multiple antennas. The obvious strategy is for the relay node to extract the individual packets from the two end nodes and mix the two packets to form a network-coded packet. In this paper, we propose a new scheme called MIMO PNC (physical network coding), in which the relay extracts the summation and difference of the two end packets and then converts them to the network-coded form. MIMO PNC is a natural combination of the single-antenna PNC scheme and the linear MIMO detection scheme. The advantages of MIMO PNC are many. First, it removes the stringent carrier-phase requirement in single-antenna PNC. Second, it is linear in complexity with respect to the constellation size and the number of simultaneous data streams in MIMO. Simulation shows that MIMO PNC outperforms the straightforward MIMO NC significantly under random Rayleigh fading channel. Based on our analysis, we further conjecture that MIMO PNC outperforms MIMO NC under all possible realizations of the channel.