Honglei Miao

Joint Beam-Frequency Multiuser Scheduling for Millimeter-Wave Downlink Multiplexing

Millimeter-wave (mmWave) communication is envisioned to be a promising technology to cater for the continuous growth of wireless communication capacity demand. To compensate severe path loss for mmWave signals, mmWave system typically employs beamforming technique to achieve essential antenna gain. To provide services to multiple user equipment (UE), mmWave system needs to schedule UEs in both frequency and beam domain to achieve optimal target utility function. To this end, this paper proposes an efficient joint beam-frequency scheduling algorithm to achieve target scheduling metric while possessing reasonable complexity. As the results of the scheduling algorithm, multiple UEs are optimally multiplexed in both frequency and beam domains in terms of target scheduling metric.

Physical downlink control channel for 5G new radio

New radio technologies for the fifth generation of wireless system have been extensively studied globally. Specifically, air interface protocols for 5G radio access network will be standardized in coming years by 3GPP. All basic physical layer functions for the new radio system are currently under active development in 3GPP. Due to its crucial function in scheduled system, physical layer control channel is a core element to enable all physical layer data transmission. In particular, search space allocation and transmission schemes are fundamental problems of control channel design. Both aspects have ultimate impacts on achievable control channel coverage, capacity and spectrum efficiency. As such, search space design and promising transmission schemes for control channels are thoroughly studied in this paper. Both distributed and localized search spaces are proposed to accommodate different means of control channel transmission depending on availability of channel state information at the base station. Furthermore, two types of transmit diversity schemes with different diversity orders are developed and compared by Monte-Carlo simulations. It is demonstrated from simulation results that SFBC based transmit diversity outperforms per-RE precoder cycling scheme. Moreover, high order transmit diversity schemes are also proposed and simulation results thereof exhibit clear performance benefits.

Cell Search for a Millimeter Wave Cellular System with 1-Bit Quantization at the Receiver

For 5G it will be important to leverage the available millimeter wave spectrum. Communication at high carrier frequencies requires antenna arrays at both the base and mobile station. A 1-bit analog to digital converter can effectively reduce the complexity and power consumption of the analog frontend. This is especially interesting in the context of large antenna arrays with a sizable signal bandwidth. In this paper we investigate the cell search capabilities of a mobile station with an antenna array and an analog frontend with 1-bit quantization behind each antenna. We derive the Likelihood Ratio Test (LRT) for this problem with full channel knowledge. We also show the generalized Likelihood Ratio Test (GLRT) for a case without channel knowledge, and compare the performance to practical algorithm based on correlation. We show that the practical correlation achieves a similar performance compared to the theoretical optimal GLRT. Compared to a system with high resolution analog to digital conversion our results show the theoretical derived SNR gap of 2 dB.

Heterogeneous beamspace design for 5g millimeter-wave systems

In the last years, the interest on millimeter wave communications increased due to the high potentiality foreseen to face the continuous growth of wireless communications capacity demand. One of the major drawback is represented by the limited coverage capacity. In order to cope with it, beamformers that generate beams with very narrow beams have been studied. Special attention has to be devoted to the tradeoff between coverage distance and area covered by the beam: depending on the UEs deployment, a too narrow beam might result into a low throughput and spectrum efficiency. In this paper a new solution to improve the cell coverage and the spectrum efficiency is proposed. The idea is based on the fact that the beamformers are designed to be flexible to choose the beam from a codebook of beams with different widths and different directions. The choice depends on a scheduling algorithm designed to maximize the performance of the system.