Zexian Li

Recent advancements in M2M communications in 4G networks and evolution towards 5G

Machine-to-Machine (M2M) communications is considered to be one of the key enablers for the provisioning of advanced applications and services such as smart cities and hospitals, as well as automated vehicular and industrial automation operation. Currently, in LTE-Advanced systems, the main focus has been on supporting massive deployment of low cost devices, with enhanced radio access network coverage. In this work, we present the recent MTC enhancements in LTE system. Detailed performance analysis based on LTE system settings is also presented. The LTE capacity evaluations performed based on devices per physical resource block indicate that significantly large number of devices can already be supported in an LTE system, based on the assumptions used, with minimal system overhead. We also present an overview of some of the key scenarios, requirements and use cases currently being considered for M2M communication in fifth generation (5G) systems. The performance requirements currently being considered for massive and ultra-reliable M2M communication are also discussed.

Smart mobility management for D2D communications in 5G networks

Direct device-to-device (D2D) communications is regarded as a promising technology to provide low-power, high-data rate and low-latency services between end-users in the future 5G networks. However, it may not always be feasible to provide low-latency reliable communication between end-users due to the nature of mobility. For instance, the latency could be increased when several controlling nodes have to exchange D2D related information among each other. Moreover, the introduced signaling overhead due to D2D operation need to be minimized. Therefore, in this paper, we propose several mobility management solutions with their technical challenges and expected gains under the assumptions of 5G small cell networks.

The METIS 5G System Concept: Meeting the 5G Requirements

The development of every new generation of wireless communication systems starts with bold, high-level requirements and predictions of its capabilities. The 5G system will not only have to surpass previous generations with respect to rate and capacity, but also address new usage scenarios with very diverse requirements, including various kinds of machine-type communication. Following this, the METIS project has developed a 5G system concept consisting of three generic 5G services: extreme mobile broadband, massive machine-type communication, and ultra-reliable MTC, supported by four main enablers: a lean system control plane, a dynamic radio access network, localized contents and traffic flows, and a spectrum toolbox. This article describes the most important system-level 5G features, enabled by the concept, necessary to meet the very diverse 5G requirements. System-level evaluation results of the METIS 5G system concept are presented, and we conclude that the 5G requirements can be met with the proposed system concept.

Towards the METIS 5G concept: First view on Horizontal Topics concepts

METIS is developing a 5G system concept that meets the requirements of the beyond-2020 connected information society and supports new usage scenarios. To meet the objectives METIS uses Horizontal Topics (HT) that addresses a key new challenge, identifies necessary new functionalities and proposes HT-specific concepts. This paper presents an initial view of the HT-specific concepts for each of the METIS HTs: Direct Device-to-Device Communication, Massive Machine Communication, Moving Networks, Ultra-Dense Networks, and Ultra-Reliable Communication. It also describes how the HT-specific concepts will be integrated into one overall METIS 5G concept.

Analysis of transmission methods for ultra-reliable communications

Fifth generation of cellular systems is expected to widely enable machine-type communications (MTC). The envisioned applications and services for MTC have diverse requirements which are not fully supported with current wireless systems. Ultra-reliable communications (URC) with low-latency is an essential feature for mission-critical applications, such as industrial automation, public safety, and vehicular safety applications. This feature guarantees a communication service with a high level of reliability. This paper investigates the feasibility and efficiency of URC over wireless links. It also analyzes the effectiveness of different transmission methods, including spatial diversity and support of hybrid automatic repeat request (HARQ). Finally, the importance of reliable feedback information is highlighted.

Link adaptation design for ultra-reliable communications

The fifth generation (5G) of cellular networks is expected to provide connectivity for a wide range of services. This requires the network to encounter novel features. Ultra-reliable communications (URC) is one of the considered features, which provides a certain level of communication service almost all the time. This is essential in order to support mission-critical applications, such as industrial automation, public safety, and vehicular communications. This paper studies link adaptation optimization for URC, considering errors in both data and feedback channels. As the implementation of optimal link adaptation is challenging, particularly, for downlink transmissions due to the limited feedback channel, a simple link adaption scheme is also proposed. Results reveal that the performances of the proposed and optimal link adaptation schemes are close. Hence, the proposed scheme can be utilized to efficiently support URC in cellular networks.

Ultra-reliable communication in a factory environment for 5G wireless networks: Link level and deployment study

The focus of this paper on mission-critical communications in a 5G cellular communication system. Technologies to provide ultra-reliable communication, with 99.999 % availability in a factory environment are studied. We have analysed the feasibility requirements for ultra-reliable communication and obtained the loss margins against path loss, shadow and fast fading. We also study the effect of increased interference due to higher deployment density on offered reliable rates and packet delays. Resource allocation schemes based on full and orthogonal resource sharing, as well as power control are compared. Last, the importance of multi-hop communication and multi-point coordination schemes are highlighted to improve the reliable communication in presence of interference and clutter.

Delay analysis of network architectures for machine-to-machine communications in LTE system

Machine-to-machine communications has emerged to provide autonomic communications for a wide variety of intelligent services and applications. Among different communication technologies available for connecting machines, cellular-based systems have gained more attention as backhaul networks due to ubiquitous coverage and mobility support. The diverse ranges of service requirements as well as machine constraints require adopting different network architectures. This paper reviews three M2M network architectures to integrate machines into the LTE system and analyzes their associated communication delays. It also presents how the appropriate networks can be selected for some machine-to-machine applications, fulfilling their latency constraints.

Selective multi-hop relaying for ultra-reliable communication in a factory environment

Evolving 5G cellular communication is envisioned to enable connectivity for a wide range of new use cases. The focus on mission-critical communications, such as factory automation, public safety and vehicular safety applications presses the demand for ultra-reliable communication. In this paper, we investigate by various means of multi-hop relaying schemes to improve the reliable communication in a factory environment. Impacts due to half- and full-duplex operation at relay nodes are studied together with resource allocation. No retransmissions are considered and the relaying schemes are limited to two hops to meet the low latency constraint. Performance evaluations in a factory scenario are shown. We illustrate that in a network of uncoordinated cells one can exploit the varying fading profiles and can improve the offered reliable rate using multi-hop communication.

Optimized transmission and resource allocation strategies for ultra-reliable communications

Fifth generation (5G) wireless systems will provide connectivity for a wide range of new applications with diverse requirements. In part, the network needs to support ultra-reliable communications with low-latency (URLLC) for mission-critical applications. For these applications, the generated data should be delivered with a limited number of transmission attempts with high success probability. This paper considers the optimal transmission and resource allocations for URLLC in cellular systems. The resource allocations are derived for the fixed and adaptive transmission attempt assignments. The analysis results reveal that both fixed and adaptive transmission assignments, applicable to automatic repeat request (ARQ) and hybrid ARQ (HARQ) schemes, can reduce the required resources compared to the equal transmission assignment.