IEEE Transactions on Vehicular Technology (ISSN: 0018-9545)Citation for the published paper: Wanlu, S. ; Ström, E. ; Brännström, F. et al. (2015) "Radio Resource Management for D2Dbased V2V Communication". IEEE Transactions on Vehicular Technology Abstract-Direct device-to-device (D2D) links have been proposed as a possible enabler for vehicle-to-vehicle (V2V) communications, where the incurred intra-cell interference and the stringent latency and reliability requirements are challenging issues. In this paper, we investigate the radio resource management problem for D2D-based V2V communication. Firstly, we analyze and transform the latency and reliability requirements of V2V communication into optimization constraints that are computable using only the slowly varying channel information. This transformation opens the possibility of extending certain existing D2D techniques to cater for V2V communication. Secondly, we propose a problem formulation that fulfills the different requirements of V2V communication and traditional cellular communication. Moreover, a Separate resOurce bLock and powEr allocatioN (SOLEN) algorithm is proposed to solve this problem. Finally, simulations are presented to evaluate different schemes, which illustrate the necessity of careful design when extending D2D methods to V2V communication and also show promising performance of the proposed SOLEN algorithm.

Abstract-Deploying direct device-to-device (D2D) links is a promising technology for vehicle-to-X (V2X) applications. However, intra-cell interference, along with stringent requirements on latency and reliability, are challenging issues. In this paper, we study the radio resource management problem for D2D-based safety-critical V2X communications. We first transform the V2X requirements into the constraints that are computable using slowly varying channel state information only. Secondly, we formulate an optimization problem, taking into account the requirements of both vehicular users (V-UEs) and cellular users (C-UEs), where resource sharing can take place not only between a V-UE and a C-UE but also among different VUEs. The NP-hardness of the problem is rigorously proved. Moreover, a heuristic algorithm, called Cluster-based Resource block sharing and pOWer allocatioN (CROWN), is proposed to solve this problem. Finally, simulations results indicate promising performance of the CROWN scheme.

Abstract-Direct device-to-device (D2D) communication has been proposed as a possible enabler for vehicle-to-vehicle (V2V) applications, where the incurred intra-cell interference and the stringent latency and reliability requirements are challenging issues. In this paper, we investigate the radio resource management problem for D2D-based V2V communications. Firstly, we analyze and mathematically model the actual requirements for vehicular communications and traditional cellular links. Secondly, we propose a problem formulation to fulfill these requirements, and then a Separate Resource Block allocation and Power control (SRBP) algorithm to solve this problem. Finally, simulations are presented to illustrate the improved performance of the proposed SRBP scheme compared to some other existing methods. I. INTRODUCTION A. MotivationRecently, vehicle-to-vehicle (V2V) communications have attracted great interest. Usually, these types of applications have a strongly localized nature, i.e., requiring cooperation between vehicles in close proximity. Furthermore, other common features to most applications are real-time requirements, as well as strict requirements on reliability and access availability. For instance, the EU project METIS considers that a maximum end-to-end delay of 5 ms, with transmission reliability of 99.999% should be guaranteed [1].Current legacy solutions for V2V communications are adhoc communications over the 802.11p standard and backendbased communications over the Long Term Evolution (LTE) cellular standard. The main problem with the 802.11p legacy system is that it is mainly optimized for a WLAN-type of environment with no or very low mobility. On the other hand, in LTE systems, as analyzed by [2], the performance for vehicular communications is not satisfactory, especially in terms of latency and reliability. Therefore, there is a strong desire of finding better solutions to support V2V communications.Meanwhile, device-to-device (D2D) communication is identified as one of the technology complements for next generation communication system. In a D2D underlaying cellular infrastructure, two physically close user equipment (UE) devices can directly communicate with each other by sharing the same resources used by regular cellular UEs (C-UEs). Correspondingly, three promising gains, i.e., proximity gain, reuse gain, and hop gain, may be offered [3].By comparing the quality of service (QoS) requirements of V2V communications and the potential benefits of D2D

Abstract-In this paper, we present a QoS routing protocol called GVGrid for multi-hop mobile ad hoc networks constructed by vehicles, i.e., vehicular ad hoc networks (VANETs). GVGrid constructs a route on demand from a source (a fixed node or a base station) to vehicles that reside in or drive through a specified geographic region. The goal of GVGrid is to maintain a high quality route, i.e. a robust route for the vehicles' movement. Such a route can be used for high quality communication and data transmission between roadsides and vehicles, or between vehicles. The experimental results have shown that GVGrid could provide routes with longer lifetime, compared with an existing routing protocol for VANETs.

IEEE 802.11ah is an emerging Wireless LAN (WLAN) standard that defines a WLAN system operating at sub 1 GHz license-exempt bands. Thanks to the favorable propagation characteristics of the low frequency spectra, 802.11ah can provide much improved transmission range compared with the conventional 802.11 WLANs operating at 2.4 GHz and 5 GHz bands. 802.11ah can be used for various purposes including large scale sensor networks, extended range hotspot, and outdoor Wi-Fi for cellular traffic offloading, whereas the available bandwidth is relatively narrow. In this paper, we give a technical overview of 802.11ah Physical (PHY) layer and Medium Access Control (MAC) layer. For the 802.11ah PHY, which is designed based on the down-clocked operation of IEEE 802.11ac's PHY layer, we describe its channelization and transmission modes. Besides, 802.11ah MAC layer has adopted some enhancements to fulfill the expected system requirements. These enhancements include the improvement of power saving features, support of large number of stations, efficient medium access mechanisms and throughput enhancements by greater compactness of various frame formats. Through the numerical analysis, we evaluate the transmission range for indoor and outdoor environments and the theoretical throughput with newly defined channel access mechanisms.