Power allocation in a QoS-aware cellular-based vehicular communication system.

Masters Degree. University of KwaZulu- Natal, Durban.The task of a driver assistance system is to monitor the surrounding environment of a vehicle and provide an appropriate response in the case of detecting any hazardous condition. Such operation requires real-time processing of a large amount of information, which is gathered by a variety of sensors. Vehicular communication in future vehicles can pave the way for designing highly efficient and cost-effective driver assistance systems based on collaborative and remote processing solutions. The main transmission links of vehicular communication systems are vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I). In this research, a cellular-based vehicular communication system is proposed where Device-to-device (D2D) communication links are considered for establishing V2V links, and cellular communication links are employed for V2I links. D2D communication is one of the enablers of the next generation of cellular networks for improving spectrum and power utilization. D2D communication allows direct communication between user equipments within a cellular system. Nevertheless, implementing D2D communication should not defect nearby ongoing communication services. As a result, interference management is a significant aspect of designing D2D communication systems. Communication links in a cellular network are supposed to support a required level of data rates. The capacity of a communication channel is directly proportional to the energy of a transmitted signal, and in fact, achieving the desired level of Quality of Service (QoS) requires careful control of transmission power for all the radio sources within a system. Among different methods that are recommended for D2D communications, in-band D2D can offer better control over power transmission sources. In an underlay in-band D2D communication system, D2D user equipments (DUEs) usually reuse the cellular uplink (UL) spectrum. In such a system, the level of interference can effectively be managed by controlling the level of power that is transmitted by user equipments. To effectively perform the interference management, knowledge of the channel state information is required. However, as a result of the distributed nature of DUEs, such information is not fully attainable in a practical D2D system. Therefore, statistical methods are employed to find boundaries on the allocated transmission powers for achieving sufficient spectral efficiencies in V2I and V2V links without considering any prior knowledge on vehicles’ locations or the channel state information. Furthermore, the concepts of massive multiple-input multiple-output and underlay D2D communication sharing the uplink spectrum of a cellular system are used to minimize the interference effect

Game-theoretic Resource Allocation Methods for Device-to-Device (D2D) Communication

Device-to-device (D2D) communication underlaying cellular networks allows mobile devices such as smartphones and tablets to use the licensed spectrum allocated to cellular services for direct peer-to-peer transmission. D2D communication can use either one-hop transmission (i.e., in D2D direct communication) or multi-hop cluster-based transmission (i.e., in D2D local area networks). The D2D devices can compete or cooperate with each other to reuse the radio resources in D2D networks. Therefore, resource allocation and access for D2D communication can be treated as games. The theories behind these games provide a variety of mathematical tools to effectively model and analyze the individual or group behaviors of D2D users. In addition, game models can provide distributed solutions to the resource allocation problems for D2D communication. The aim of this article is to demonstrate the applications of game-theoretic models to study the radio resource allocation issues in D2D communication. The article also outlines several key open research directions.Comment: Accepted. IEEE Wireless Comms Mag. 201

Resource Allocation for Device-to-Device Communications Underlaying Heterogeneous Cellular Networks Using Coalitional Games

Heterogeneous cellular networks (HCNs) with millimeter wave (mmWave) communications included are emerging as a promising candidate for the fifth generation mobile network. With highly directional antenna arrays, mmWave links are able to provide several-Gbps transmission rate. However, mmWave links are easily blocked without line of sight. On the other hand, D2D communications have been proposed to support many content based applications, and need to share resources with users in HCNs to improve spectral reuse and enhance system capacity. Consequently, an efficient resource allocation scheme for D2D pairs among both mmWave and the cellular carrier band is needed. In this paper, we first formulate the problem of the resource allocation among mmWave and the cellular band for multiple D2D pairs from the view point of game theory. Then, with the characteristics of cellular and mmWave communications considered, we propose a coalition formation game to maximize the system sum rate in statistical average sense. We also theoretically prove that our proposed game converges to a Nash-stable equilibrium and further reaches the near-optimal solution with fast convergence rate. Through extensive simulations under various system parameters, we demonstrate the superior performance of our scheme in terms of the system sum rate compared with several other practical schemes.Comment: 13 pages, 12 figure

Benchmarking Practical RRM Algorithms for D2D Communications in LTE Advanced

Device-to-device (D2D) communication integrated into cellular networks is a means to take advantage of the proximity of devices and allow for reusing cellular resources and thereby to increase the user bitrates and the system capacity. However, when D2D (in the 3rd Generation Partnership Project also called Long Term Evolution (LTE) Direct) communication in cellular spectrum is supported, there is a need to revisit and modify the existing radio resource management (RRM) and power control (PC) techniques to realize the potential of the proximity and reuse gains and to limit the interference at the cellular layer. In this paper, we examine the performance of the flexible LTE PC tool box and benchmark it against a utility optimal iterative scheme. We find that the open loop PC scheme of LTE performs well for cellular users both in terms of the used transmit power levels and the achieved signal-to-interference-and-noise-ratio (SINR) distribution. However, the performance of the D2D users as well as the overall system throughput can be boosted by the utility optimal scheme, because the utility maximizing scheme takes better advantage of both the proximity and the reuse gains. Therefore, in this paper we propose a hybrid PC scheme, in which cellular users employ the open loop path compensation method of LTE, while D2D users use the utility optimizing distributed PC scheme. In order to protect the cellular layer, the hybrid scheme allows for limiting the interference caused by the D2D layer at the cost of having a small impact on the performance of the D2D layer. To ensure feasibility, we limit the number of iterations to a practically feasible level. We make the point that the hybrid scheme is not only near optimal, but it also allows for a distributed implementation for the D2D users, while preserving the LTE PC scheme for the cellular users.Comment: 30 pages, submitted for review April-2013. See also: G. Fodor, M. Johansson, D. P. Demia, B. Marco, and A. Abrardo, A joint power control and resource allocation algorithm for D2D communications, KTH, Automatic Control, Tech. Rep., 2012, qC 20120910, http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10205

Radio Link Enabler for Context-aware D2D Communication in Reuse Mode

Device-to-Device (D2D) communication is considered as one of the key technologies for the fifth generation wireless communication system (5G) due to certain benefits provided, e.g. traffic offload and low end-to-end latency. A D2D link can reuse resource of a cellular user for its own transmission, while mutual interference in between these two links is introduced. In this paper, we propose a smart radio resource management (RRM) algorithm which enables D2D communication to reuse cellular resource, by taking into account of context information. Besides, signaling schemes with high efficiency are also given in this work to enable the proposed RRM algorithm. Simulation results demonstrate the performance improvement of the proposed scheme in terms of the overall cell capacity