Joint fixed beamforming and eigenmode precoding for super high bit rate massive MIMO systems using higher frequency bands

A massive MIMO wireless system is a multiuser MISO system where base stations consist of a large number of antennas with respect to number of user devices, each equipped with a single antenna. Massive MIMO is seen as the way forward in enhancing the transmission rate and user capacity in 5G wireless. The potential of massive MIMO system lies in the ability to almost always realize multiuser channels with near zero mutual coupling. Coupling factor reduces by 1/2 for each doubling of transmit antennas. In a high bit rate massive MIMO system with m base station antennas and n users, downlink capacity increases as log2⁡m bps/Hz, and the capacity per user reduces as log2⁡n bps/Hz. This capacity can be achieved by power sharing and using signal weighting vectors aligned to respective 1×m channels of the users. For low bit rate transmission, time sharing achieves the capacity as much as power sharing does. System capacity reduces as channel coupling factor increases. Interference avoidance or minimization strategies can be used to achieve the available capacity in such scenarios. Probability distribution of channel coupling factor is a convenient tool to predict the number of antennas needed to qualify a system as massive MIMO.

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SCHEDULING FOR MASSIVE MIMO USING CHANNEL AIGING UNDER QOS CONSTRAINTS

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/57/5/13751 ◽

2019 ◽

Vol 57 (5) ◽

pp. 617

Author(s):

Pham Hung ◽

Bac Hoai Dang ◽

Ban Tien Nguyen

Keyword(s):

Massive Mimo ◽

Mimo Systems ◽

Multiple Input Multiple Output ◽

Spatial Multiplexing ◽

Bit Rate ◽

Minimum Rate ◽

Mimo Networks ◽

Input Multiple Output ◽

Sum Rate ◽

Service Data

Massive multiple-input multiple-output (MIMO) networks support QoS (Quality of Service) by adding a new sublayer Service Data Adaption Protocol on the top of Packet Data Convergence Protocol layer to map between QoS flows and data radio bearers. In downlink for Guaranteed Bit Rate (GBR) flows, the gNB guarantees the Guaranteed Flow Bit Rate (GFBR) that defines the minimum bit rate the QoS flow can provide. So, one of the most important requirements is the minimum rate. The channel aiging helps to improve the sum-rate of Massive MIMO systems by serving more users to increase the spatial multiplexing gain without incurring additional pilot overhead. In this paper, a novel scheduler, termed QoS-Aware scheduling, is designed and proposed for Massive MIMO to use the channel aiging to increase the sum-rate but guarantee the minimum bit rate per user to support QoS. We investigate how many users are enough to serve to maximize the sum-rate while keeping the data rate per user meeting a given threshold. Through the numerical analysis we confirmed that QoS-Aware scheduling can guarantee a minimum rate per user and get a higher useful through-put (goodput) than conventional channel aiging schedulers.

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