As heterogeneous networks (HetNets) emerge as one of the most promising developments toward realizing the target specifications of Long Term Evolution (LTE) and LTE-Advanced (LTE-A) networks, radio resource management (RRM) research for such networks has, in recent times, been intensively pursued Clearly, recent research mainly concentrates on the aspect of interference mitigation Other RRM aspects, such as radio resource utilization, fairness, complexity, and QoS, have not been given much attention In this paper, we aim to provide an overview of the key challenges arising from HetNets and highlight their importance Subsequently, we present a comprehensive survey of the RRM schemes that have been studied in recent years for LTE/LTE-A HetNets, with a particular focus on those for femtocells and relay nodes Furthermore, we classify these RRM schemes according to their underlying approaches In addition, these RRM schemes are qualitatively analyzed and compared to each other We also identify a number of potential research directions for future RRM development Finally, we discuss the lack of current RRM research and the importance of multi-objective RRM studies

Recent Advances in Radio Resource Management for Heterogeneous LTE/LTE-A Networks

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.

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

An approach to increase road capacity consists in making vehicles move much closer to each other, i.e. using platoons, and to avoid the constant stop-and-go in urban traffic. This paper addresses the studies of new models to allow the research of cooperative and autonomous communication-enabled vehicles, with platooning capabilities, and the addition of new features in SUMO (Simulation for Urban MObility) to allow the simulation of those models. Simulations results of vehicle platoons using constant spacing instead of the more common constant time headway, with intervehicle communications, are reported in the paper. The platoon leaders are controlled by an external application and the simulation platform works at the subsecond level.

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Platooning of autonomous vehicles with intervehicle communications in SUMO traffic simulator

A device configured to calculate a cell quality ranking criterion for a measured cell, wherein calculating is performed by taking into account at least a signal quality of a backhaul link between a relay node (RN) and an access node. The device may be one of a user equipment (UE), RN, an access node, and a component in a network.

Determining link quality for networks having relays

Wireless factory automation has been receiving much interest in recent years due to its advantages of low cost and high flexibility over the traditional wired networks. Factory automation is also considered as one of the important use-cases of the 5th generation (5G) cellular system. In this paper, we present comprehensive system level simulation results to evaluate the performance of LTE and new 5G radio-interface design concepts in a realistic factory deployment scenario. We believe that our detailed evaluation studies bring valuable insights to show the potential of 3GPP technologies for different factory use-cases.

Ultra-reliable and low-latency communication for wireless factory automation: From LTE to 5G

This article presents the architecture of MCN toward 3G LTE-Advanced with TDD. On the assumption that L2 RN and L3 RN can provide their own RRM functions, several important RRM functions including routing, link adaptation, and scheduling in MAC layers at RNs can help the eNB to handle the radio resources efficiently. In general, the RN with higher implementation complexity has the ability to provide more flexible RRM with more overhead. Our dynamic system-level simulations show that the MCN outperform the networks without relaying in terms of SINR and throughput.

Multihop cellular networks toward LTE-advanced

In the relay enhanced cellular network (REC), user terminals can flexibly select transmission routes to get service. This paper investigated the effect of route selection schemes on the system performance of REC. Besides the traditional schemes based on signal power and signal-to-interference-plus-noise-ratio (SINR), we evaluated the effective spectral efficiency (SE) based approach which takes into account the feature of multihop transmission. We compared these three schemes through system level simulation, which is based on 3GPP LTE system enhanced with 2-hop fixed relay nodes. The results confirm that the SE-based scheme outperforms the other two schemes. Moreover, the results show that the effect of route selection heavily depends on the position of RNs. The REC system with signal power or SINR based route selection scheme yields even worse throughput than the non-relay case at certain positions. However, the SE-based scheme can always guarantee the gain from relaying.

Route Selection Strategies in Cellular Networks with Two-Hop Relaying

This paper studies the performance of Voice-over-Internet-Protocol (VoIP) service in the third generation (3G) long-term evolution (LTE)-Advanced relaying networks. We propose a semi-persistent scheduling algorithm for the VoIP service in the LTE-Advanced relaying networks. The performance of the presented algorithm is verified by system-level simulation. Deployments with different number of relay nodes are taken into account in the simulations. The results show that through deploying relays, the packet delay of cell edge users can be dramatically decreased. Moreover, the VoIP capacity of the relaying networks can also be increased obviously.

Semi-persistent scheduling for VoIP service in the LTE-Advanced relaying networks

Relaying is expected to be one key element of the future cellular networks. This paper focuses on 3GPP LTE-Advanced network incorporated with Type I relay nodes. We first present the required radio resource management (RRM) framework which includes routing, resource partition and scheduling functions. Then two RRM strategies are suggested: one with the conventional cellular settings, the other with further consideration on the special interference environment with relay nodes (RN). We evaluate and compare the network performances through system-level simulations under different relay deployment patterns. The results show that the interference-aware scheme could boost the coverage range of the RN and provide better cell-edge throughput when the RN density is low. Moreover, when the RN number increased, a bottleneck effect caused by the limited backhaul link capacity is observed.

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Performance of 3GPP LTE-Advanced networks with Type I relay nodes

The multihop cellular architecture with relaying is expected to be a cost-effective solution to reduce the transmission distance and increase the amount of users under more favorable channel conditions with better channel quality and higher throughput. In this article, we present the architecture and evaluate the performances of multihop cellular networks (MCNs) for thirdgeneration (3G) long-term evolution (LTE) toward its advanced networks. First, the network architecture is introduced with the specific features of 3G LTE. Then, the frame structure based on time-division duplex (TDD) for relaying is proposed, and the relay nodes (RNs) are Digital Object Identifier 10.1109/MVT.2009.933474 © PHOTO F/X2

Zhangchao Ma

Papers

Multihop cellular networks toward LTE-advanced

Route Selection Strategies in Cellular Networks with Two-Hop Relaying

Semi-persistent scheduling for VoIP service in the LTE-Advanced relaying networks

Performance of 3GPP LTE-Advanced networks with Type I relay nodes

MULTIHOP CELLULAR NETWORKS TOWARD LTE-ADVANCED Its Architecture and Performance