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 probability are derived to characterize the performance of the proposed scheme. The results show that the proposed cooperative NOMA scheme can achieve superior outage performance compared to the conventional NOMA and orthogonal multiple access (OMA). In order to further improve the outage performance, an adaptive multiple access (AMA) scheme is also studied, which dynamically switches between the proposed cooperative NOMA, conventional NOMA, and OMA schemes, according to the level of residual self-interference and the quality of links. The results show that the AMA scheme outperforms the above multiple access schemes in terms of outage performance.

Full-Duplex Device-to-Device-Aided Cooperative Nonorthogonal Multiple Access

Nowadays, many disruptive Internet-of-Things (IoT) applications emerge, such as augmented/virtual reality online games, autonomous driving, and smart everything, which are massive in number, data intensive, computation intensive, and delay sensitive. Due to the mismatch between the fifth generation (5G) and the requirements of such massive IoT-enabled applications, there is a need for technological advancements and evolutions for wireless communications and networking toward the sixth-generation (6G) networks. 6G is expected to deliver extended 5G capabilities at a very high level, such as Tbps data rate, sub-ms latency, cm-level localization, and so on, which will play a significant role in supporting massive IoT devices to operate seamlessly with highly diverse service requirements. Motivated by the aforementioned facts, in this article, we present a comprehensive survey on 6G-enabled massive IoT. First, we present the drivers and requirements by summarizing the emerging IoT-enabled applications and the corresponding requirements, along with the limitations of 5G. Second, visions of 6G are provided in terms of core technical requirements, use cases, and trends. Third, a new network architecture provided by 6G to enable massive IoT is introduced, i.e., space–air–ground–underwater/sea networks enhanced by edge computing. Fourth, some breakthrough technologies, such as machine learning and blockchain, in 6G are introduced, where the motivations, applications, and open issues of these technologies for massive IoT are summarized. Finally, a use case of fully autonomous driving is presented to show 6G supports massive IoT.

Enabling Massive IoT Toward 6G: A Comprehensive Survey

Providing reliable broadband wireless communications in high mobility environments, such as high-speed railway systems, remains one of the main challenges faced by the development of the next generation wireless systems. This paper provides a systematic review of high mobility communications. We first summarize a list of key challenges and opportunities in high mobility communication systems, then provide comprehensive reviews of techniques that can address these challenges and utilize the unique opportunities. The review covers a wide spectrum of communication operations, including the accurate modeling of high mobility channels, the transceiver structures that can exploit the properties of high mobility environments, the signal processing techniques that can harvest the benefits (e.g., Doppler diversity) and mitigate the impairments (e.g., carrier frequency offset, intercarrier interference, channel estimation errors) in high mobility systems, and the mobility management and network architectures that are designed specifically for high mobility systems. The survey focuses primarily on physical layer operations, which are affected the most by the mobile environment, with some additional discussions on higher layer operations, such as handover management and control-plane/user-plane decoupling, which are essential to high mobility operations. Future research directions on high mobility communications are summarized at the end of this paper.

A Survey on High Mobility Wireless Communications: Challenges, Opportunities and Solutions

Future 5th generation networks are expected to enable three key services—enhanced mobile broadband, massive machine type communications and ultra-reliable and low latency communications (URLLC). As per the 3rd generation partnership project URLLC requirements, it is expected that the reliability of one transmission of a 32 byte packet will be at least 99.999% and the latency will be at most 1 ms. This unprecedented level of reliability and latency will yield various new applications, such as smart grids, industrial automation and intelligent transport systems. In this survey we present potential future URLLC applications, and summarize the corresponding reliability and latency requirements. We provide a comprehensive discussion on physical (PHY) and medium access control (MAC) layer techniques that enable URLLC, addressing both licensed and unlicensed bands. This paper evaluates the relevant PHY and MAC techniques for their ability to improve the reliability and reduce the latency. We identify that enabling long-term evolution to coexist in the unlicensed spectrum is also a potential enabler of URLLC in the unlicensed band, and provide numerical evaluations. Lastly, this paper discusses the potential future research directions and challenges in achieving the URLLC requirements.

/pdf/enabling-technologies-for-ultra-reliable-and-low-latency-44un8h2u5m.pdf

Enabling Technologies for Ultra-Reliable and Low Latency Communications: From PHY and MAC Layer Perspectives

Spectrum handoff in cognitive radio networks

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 peoples practical requirements and what can be offered by the 4G technologies. Consequently, the research and development for the fifth generation (5G) systems have already been started. This article presents an overview of potential network architecture and highlights several promising techniques which could be employed in the future 5G systems. These techniques include non-orthogonal multiple access (NOMA), massive multiple input and multiple output (MIMO), cooperative communications and network coding, full duplex (FD), device-to-device (D2D) communications, millimeter wave communications, automated network organization, cognitive radio (CR), and green communications. The state-of-art and implementation issue of these techniques are also addressed.

http://www.lancaster.ac.uk/staff/dingz/Key%20techniques%20for%205G%20wireless%20communications_network%20architecture,%20physical%20layer,%20and%20MAC%20layer%20perspectives.pdf

Key techniques for 5G wireless communications:network architecture, physical layer, and MAC layer perspectives

Based on the analysis of the basic principle and characteristics of RFID, the existing RFID indoor location-sensing system LANDMARC was discussed in detail. Then, an enhanced nearest neighbor positioning algorithm was proposed based on multi-level error processing. Simulation results show that the enhanced nearest neighbor algorithm can achieve better positioning accuracy than the existing nearest neighbor algorithms.

RFID technology and its application in indoor positioning

In this paper, an adaptive access control mechanism is proposed for License Assisted Access (LAA) and Wi-Fi coexistence in unlicensed band. In the proposed mechanism, an adaptive adjustment mechanism for Clear Channel Assessment (CCA) is introduced based on the channel usage efficiency for Wi-Fi system and cellular system. When the access priority of Wi-Fi is guaranteed, the backoff window size of both Wi-Fi access points (APs) and cellular base stations (BSs) can be adjusted adaptively according to the quality-of-service (QoS) of different nodes. With the proposed mechanism, the delay and access success rate performance of coexisting system can be improved, while the normalized throughput can be guaranteed in the high density scenarios. Markov models are used for theoretical analysis. System level simulation results validate the advantages of the proposed mechanism compared with the existing mechanisms.

An adaptive access control mechanism for LAA and Wi-Fi coexistence in unlicensed band

The number of Machine-to-Machine (M2M) traffics is rapidly increasing in cellular communication systems. In order to ensure a maximum system capacity, the communication resources should be allocated appropriately to M2M traffics and common Human-to-Human (H2H) traffics. In this paper, a preamble allocation method for M2M services in 3GPP LTE system is presented. This method splits the set of available random access preambles into three subsets: the first one is for H2H services only, the second is for both H2H and M2M services and the third is for M2M services only. We model and analyze the throughput performance of the proposed method, and compare it with the two major candidate preamble allocation methods under consideration for possible adoption in LTE-Advanced networks. It is shown that the proposed method performs much better in most practical situations.

A preamble allocation method for M2M traffics in 3GPP LTE-A networks

Disjoint difference sets with regard to the largest elements are used to construct multiple-burst error-correcting codes using majority-logic decoding. Almost all of D.M. Mandelbaum's (1972) codes are improved with shorter lengths. Because they are quasi-cyclic and majority-logic decodable, they are of practical interest. >

Fan Pingzhi

Papers

Key techniques for 5G wireless communications:network architecture, physical layer, and MAC layer perspectives

RFID technology and its application in indoor positioning

An adaptive access control mechanism for LAA and Wi-Fi coexistence in unlicensed band

A preamble allocation method for M2M traffics in 3GPP LTE-A networks

On the constructions of multiple-burst error-correcting codes