Zhengquan Zhang

• Southwest Jiaotong University

In this paper, we develop a secure multi-layer mobile edge computing (MEC) system where an unmanned aerial vehicle (UAV) equipped with a reconfigurable intelligent surface (RIS) acts as an aerial edge server and assists the offloading from multiple ground users to a base station (BS), in the presence of a full-duplex active eavesdropper (AE). To en...

Orthogonal time-frequency space (OTFS) is a promising technique for high mobility wireless communications, as it approaches a sparse representation of doubly-selective fading channel and can obtain delay-Doppler (DD) diversity gain. However, in practical OTFS systems, fractional channel parameter is a great challenge and will seriously deteriorates...

Due to transmission of train control and dispatch commands, the ultra high reliability is required for railway wireless communication systems (RWCS). However, the quality of service (QoS) of RWCS is affected by external interference and jamming seriously in railway transportation. The external interference and jamming generated from intentional and...

This paper studies user scheduling and power allocation problem to maximize the energy efficiency (EE) for non-orthogonal multiple access (NOMA) in downlink Coordinated Multi-Point networks. In the proposed framework, a more practical scenario the imperfect channel state information, imperfect successive interference cancellation and data outage ar...

In this paper, we consider a downlink non-orthogonal multiple access (NOMA) enabled heterogeneous small cells network (HSCN), where the macro base station simultaneously communicates with multiple small cell base stations (SBSs) through wireless backhaul. In each small cell, users are grouped by NOMA bases and then served by their respective SBS. T...

We report on flash sintering using a contactless approach. The process is based on dielectric barrier discharge atmospheric cold plasma which allows flash sintering without external preheating. The evenly spread cold plasma plume contributed to homogenous densification of zirconia samples, instead arc discharge resulted in un-sintered and cracked m...

In this paper, we consider a downlink non-orthogonal multiple access (NOMA) heterogeneous small cell networks (HSCN), where the macro base station (MBS) simultaneously communicate with multiple small cell base stations (SBS) through the wireless backhauls. The goal is to investigate an energy-efficient power, and bandwidth allocation scheme aiming...

A key enabler for the intelligent information society of 2030, 6G networks are expected to provide performance superior to 5G and satisfy emerging services and applications. In this article, we present our vision of what 6G will be and describe usage scenarios and requirements for multi-terabyte per second (Tb/s) and intelligent 6G networks. We pre...

Non-orthogonal multiple access (NOMA) enables the messages of multiple users to be multiplexed in the power domain by superposition coding at the transmitter side and to be decoded by successive interference cancelation (SIC) at the receiver side. This non-orthogonality enables each user to occupy the whole time–frequency resources such that it ove...

Heterogeneous ultradense networks (H-UDNs) are one key enabler for fifth-generation (5G) wireless networks and beyond to satisfy the explosive growth of mobile data traffic, which exploits spatial reuse of scarce spectrum by deploying massive base stations (BSs) to boost network capacity and enhance network coverage. In this article, we present the...

Power domain non-orthogonal transmission is a promising technology for 5G wireless networks and beyond, as it can achieve higher spectrum efficiency than the orthogonal kind by multiplexing multiple users in the power domain. This article studies power domain non-orthogonal transmission for cellular mobile broadcasting to satisfy the increasing dem...

Ultra-dense networks (UDN) are the promising technology for the fifth-generation (5G) wireless networks and beyond to significantly boost network capacity and improve network coverage by exploiting spatial spectrum reuse through the deployment of massive base stations (BSs). In this paper, the fundamental tradeoffs of non-orthogonal multicast, mult...

Non-orthogonal multiple-access (NOMA) with perfect successive interference cancellation (SIC) is an emerging research topic in the future wireless communication systems. In this work, NOMA is applied to dual-hop relaying systems, where the signals are transmitted with the aid of either decodeand- forward (DF) or amplify-and-forward (AF) relay. Exac...

Millimeter wave (mmWave) wireless networks can operate in single-cell point-to-multipoint (SC-PTM) mode to provide local multicast services efficiently. In this paper, the performance of multicast mmWave wireless networks is studied, through stochastic geometry. Then, the use of power domain non-orthogonal multiple access (NOMA) for enhancing mmWav...

Broadcasting/multicasting is an efficient mechanism for multimedia communications due to its high spectrum efficiency, which achieves point-to-multipoint transmission on the same radio resources. To satisfy the increasing demands for multimedia broadcast multicast service (MBMS), we present a power domain non-orthogonal MBMS transmission scheme in...

We propose a novel two-timeslot two-way full-duplex (FD) relaying scheme, in which the access link and the backhaul link are divided in the time domain, and we study the average end-to-end rate and the outage performance. According to the user equipment capability and services, we investigate two scenarios: three-node I-and four-node Y-relaying cha...

In this paper, we systematically study the average rate and outage probability tradeoffs of full-duplex two-way and one-way relaying under residual self-interference. Among various relaying protocols, two common of them are considered: amplify-and-forward (AF) and decode-and-forward (DF). Furthermore, we consider the application of physical-layer n...

This paper presents a full-duplex device-to-device (D2D)-aided cooperative nonorthogonal multiple access (NOMA) scheme to improve the outage performance of the NOMA-weak user in a NOMA user pair, where the NOMA-weak user is helped by the NOMA-strong user with the capability of full-duplex D2D communications. The expressions for the outage probabili...

The fourth generation (4G) mobile communication systems are offering service worldwide steadily. Although 4G systems could be loaded with much more services and data than previous systems, there is still a dramatic gap between the people’s practical requirements and what can be offered by the 4G technologies. Consequently, the research and developm...