LTE蜂窝系统中的D2D工作模式研究

随着移动通信频谱资源的越来越稀缺,为了更加充分地利用现有频谱资源,提出了D2D。D2D技术可以充分地利用现有的频谱资源,提高系统的吞吐量。文章讨论了LTE(长期演进)蜂窝系统中引入D2D通信技术后面临的模式选择问题:何时启用D2D模式,以及包含几种D2D工作模式,蜂窝模式与D2D模式之间的切换问题。     

蜂窝网络下终端直通安全通信关键技术研究

无线移动用户和数据的爆炸性增长给蜂窝网络系统容量带来了巨大挑战。终端直通(Device-to-Device,D2 D)通信技术通过提高空间利用率从而提高频谱利用率,在某些场景下使移动通信变得更加直接和高效,缓解基站压力,提高用户体验。首先给出了D2D通信系统的基本概念、组成和特点,并与传统的终端直通技术进行对比。接着综述了D2D通信中的关键技术包括邻居/服务发现、模式选择、资源分配和干扰控制等。重点从安全数据传输协议、用户身份认证和物理层安全三个方面提出了D2D系统中安全机制。最后,对D2D通信技术的发展进行展望,指出未来的发展趋势。     

TETRA数字集群系统直通模式综述

陆上集群无线电(TETRA)是目前主流的专用移动通信系统之一,它具有一种被称为直通模式(DM)的工作模式。在该模式下,无需通过网络设备就可以直接进行终端间的通信。本文的主要内容就是介绍TETRA直通模式的通信体制,并对直通模式下终端之间的通信过程进行了详细的分析。     

TETRA数字集群系统直通模式综述

陆上集群无线电(TETRA)是目前主流的专用移动通信系统之一，它具有一种被称为直通模式(DM)的工作模式。在该模式下，无需通过网络设备就可以直接进行终端间的通信。本的主要内容就是介绍TETRA直通模式的通信体制，并对直通模式下终端之间的通信过程进行了详细的分析。     

D2D通信中干扰协调算法的研究

D2D(Device-to-Device,终端直通通信)技术是指用户可以直接进行通信而不用经过基站的一种终端直通通信技术,移动蜂窝使用终端直通通信技术能够增加蜂窝系统性能,然而却带来了较多的干扰以及加大了能量损耗.为了达到用户和基站间的相互干扰,增加频谱利用效率和能量利用效率,文章以D2D 用户和速率为优化目标提出了一种联合资源分配和功率控制的方法,用以达到高能效的终端直通通信.仿真结果表明:文章提出的联合信道分配和功率控制方案,能明显减少D2D用户与蜂窝系统受到的干扰,增加蜂窝频谱利用率以及D2D用户和速率.     

蜂窝网络中基于D2D位置的联合模式选择与资源分配方案

蜂窝网络中的D2D(device-to-device,终端直通)技术可以提高频谱资源利用率和用户的吞吐量,然而,D2D通信会对蜂窝用户和其他D2D用户产生干扰,合适的模式选择与资源分配方案就变得相当重要。研究了蜂窝用户和D2D用户的干扰情况,并提出了一种基于D2D位置的联合模式选择与资源分配方案,该方案根据D2D用户在小区中的位置和终端的干扰情况对D2D用户的通信模式和资源的复用方式进行了优化,从而提升系统下行链路的性能。仿真结果表明,相比于已有方案和纯蜂窝方案,采用基于位置的联合模式选择与资源分配方案能得到更高的系统吞吐量。     

D2D通信资源调度研究现状综述

终端直通技术(D2D)是一种终端在基站控制下直接进行通信而不需要基站转发的新型通信技术。D2D引入LTE-A蜂窝系统虽然可以带来吞吐量和频谱效率的提升,但是也会带来很大的干扰。综合近些年来的研究成果,合理的资源调度算法成为降低干扰,提升系统性能的关键。首先,描述了D2D通信技术引入LTE-A蜂窝网络后的系统干扰模型。然后,从模式选择、资源分配和功率控制三个方面综述了目前国内外文献关于资源调度算法的研究成果。     

蜂窝网络中全双工D2D通信功率控制

在蜂窝网络中,采用全双工传输的设备直通(D2D)通信可以共享蜂窝通信的信道资源,提升频谱利用率和系统吞吐量.针对单对全双工D2D用户复用单个蜂窝用户的上行信道资源时,用户之间会产生同频干扰的问题,提出了一种低复杂度的功率控制算法.该算法在保证全双工D2D用户和蜂窝用户(CU)的服务质量(QoS)的前提下,最大化全双工D2D链路的吞吐量.仿真结果表明,该算法能够提高全双工D2D链路的吞吐量;全双工D2D链路吞吐量取决于蜂窝用户的QoS要求、相对距离以及自干扰消除数量的限制.     

基于TD-SCDMA网络的集群直通模式

在网络信号微弱或要求高度保密的部门,集群终端之间能直接建立通信就显得非常重要.本文首先对直通模式作了简单介绍,然后提出了一种由TD-SCDMA网络参与前期接续条件下的集群直通模式,并给出了该模式的工作方式、空中接口协议、通信建立流程和释放流程.     

基于TD—SCDMA网络的集群终端直通模式

信息化条件下的战场环境复杂,通信不顺畅的情况时有发生;这时,集群终端之间能直接建立通信就显得尤为重要。文章首先对直通模式作了简单介绍,然后提出了一种由TD—SCDMA网络参与前期接续的集群终端直通模式,并给出了该模式的工作方式、空中接口协议、通信建立流程和释放流程。这种直通模式既扩展了TD—SCDMA网络的应用范围,又提高了TD—SCDMA系统的容量,具有较高的军事应用价值。     

D2D/蜂窝通信模式切换与联合功率控制方案

设备直连（Device-to-Device, D2D）通信技术通过复用蜂窝系统的频谱资源提高频谱利用率,但D2D的引入会给蜂窝系统带来干扰。如何合理地选择D2D/蜂窝通信模式并进行功率优化控制,成为减小D2D和蜂窝系统间干扰、提升网络性能的关键。本文考虑D2D用户复用蜂窝上行链路场景,提出了一种基于距离和联合功率控制的通信模式选择方案。在该方案中,D2D用户和蜂窝用户与基站距离的比值决定了D2D用户是否采用Underlay模式进行通信,进而在约束蜂窝用户和D2D用户发射功率的条件下实现D2D链路和蜂窝链路的联合功率控制,最终推导出能够最大化系统总吞吐量的最优用户功率分配方案。根据仿真结果,本文提出的联合功率控制方案能够在降低系统间干扰的同时有效提高D2D和蜂窝系统的总吞吐量,进而提高了系统的性能。      

Energy‐efficient device‐to‐device communication using adaptive resource‐block allocation

Device‐to‐device (D2D) communication in the fifth‐generation (5G) wireless communication networks (WCNs) reuses the cellular spectrum to communicate over the direct links and offers significant performance benefits. Since the scarce radio spectrum is the most precious resource for the mobile‐network operators (MNOs), optimizing the resource allocation in WCNs is a major challenge. This paper proposes an adaptive resource‐block (RB) allocation scheme for adequate RB availability to every D2D pair in a trisectored cell of the 5G WCN. The hidden Markov model (HMM) is used to allocate RBs adaptively, promoting high resource efficiency. The stringent quality‐of‐service (QoS) and quality‐of‐experience (QoE) requirements of the evolutionary 5G WCNs must not surpass the transmission power levels. This is also addressed while using HMM for RB allocation. Thus, an energy‐efficient RB allocation is performed, with higher access rate and mean opinion score (MOS). Cell sectoring effectively manages the interference in the 5G networks amid ultrauser density. The potency of the proposed adaptive scheme has been verified through simulations. The proposed scheme is an essential approach to green communication in 5G WCNs.     

Swarm intelligence‐based radio resource management for V2V‐based D2D communication

Internet of Things is a promising paradigm that provides the future network of interconnected devices. Device‐to‐Device (D2D) communication, which is considered as an enabler for vehicle‐to‐everything applications, has become an emerging technology to optimize network performance. In this paper, we study the Radio Resource Management (RRM) issue for D2D‐based Vehicle‐to‐Vehicle communication. The RRM key role is to assure the proficient exploitation of available resources while serving users according to their quality of service parameters. An Ant Colony Optimization (ACO)‐based Resource Allocation (ACORA) scheme is proposed in this paper. Swarm intelligence algorithm ACO is adopted to reduce the computational complexity while realizing satisfactory performance. Simulation results show promising performance of our proposed ACORA scheme.     

Dynamic resource allocation for Device‐to‐Device communication underlaying cellular networks

Future cellular networks such as IMT‐Advanced are expected to allow underlaying direct Device‐to‐Device (D2D) communication for spectrum efficiency. However, enabling D2D communication in a cellular network presents a challenge in resource allocation because of the potentially severe interference it may cause to the cellular network by reusing the spectrum with the cellular users. In this paper, we analyze the resource allocation problem in a single cell system when both cellular users and D2D users are present in the system. We first consider the scenario where cellular users and D2D users are allocated resource independently and propose an optimal algorithm and a heuristic algorithm, and then extend the methods to the scenario where cellular users and D2D users are allocated resource jointly. The number of permitted D2D pairs is selected as a performance measure because it is a more specific performance measure than spectrum efficiency. The proposed schemes maximize the number of permitted D2D communication pairs in a system meanwhile avoiding the strong interference from D2D links to the cellular links. Finally, the performance of the proposed methods is evaluated through the numerical simulation. The simulation results show that the proposed methods enhance the number of permitted D2D communication pairs significantly and that the performance of the proposed scheme for jointly allocation scenario is better than that of the proposed scheme for independently allocation scenario. Copyright © 2012 John Wiley & Sons, Ltd.     

EEDOS: an energy-efficient and delay-aware offloading scheme based on device to device collaboration in mobile edge computing

Telecommunication Systems - Device to device (D2D) communication and mobile edge computing (MEC) are two promising technologies in fifth generation (5G) cellular mobile communication. Besides MEC,...     

On selecting transmission mode for D2D transmitter in underlay cellular network with a multi-antenna base station

The Device-to-Device (D2D) communication underlaying cellular networks is considered in this study. The D2D transmitter in the D2D mode can directly transmit messages to a receiver, but it may interfere with the transmission of another cellular user who shares the same uplink channel. The transmitter can also operate in a cellular mode in which no interference to another cellular user occurs. We propose a mode selection scheme that aims to minimize the transmission power of the D2D transmitter subject to constraints on the minimum required data rate and maximum interference to other cellular users. The proposed scheme is based on bounds for transmission power and is less complex than the optimal scheme. Furthermore, it requires only a few statistics and does not need a fading channel distribution. The performance of the scheme is close to optimum when the number of Base Station (BS) antennas is large, and the mean absolute deviation of the fading terms is small. We verify this with numerical results of the Rician and Rayleigh fading channels by assuming that the BS antennas are independent. The simulation results for the two correlated BS antennas are presented herein.     

D2D研究现状及发展前景

LTE Device to Device(D2D)Proximity Services(LTE终端直通近距离服务)即我们熟知的LTE-D2D(端到端)技术。2013年,D2D成为3GPP组织重点研讨技术之一,其标准化工作正在讨论完善之中。LTE-D2D是在LTE-A系统(辅助)控制或无网络基础设施的情况下,用户设备在授权频段上直接进行通信的技术。它的出现将在一定程度上缓解无线频谱资源匮乏的问题,并能够提升蜂窝系统频谱效率。文章对D2D通信的发展历程、场景和关键技术进行了介绍,最后展望D2D技术发展前景及在未来应用中的情况。     

5G网络中DR-OC型D2D通信收益模型及定价研究

Device-to-Device(D2D)通信是下一代(5G)移动网络的重要组成部分。D2D设备间在不依赖基站的情况下直接进行数据传输,并通过重复使用蜂窝小区的频率资源从而提高移动通信系统的容量。为了激励蜂窝网络用户参与到D2D通信,运营商对D2D通信的定价是一个很关键的问题。文中首先介绍了D2D的基本概念及其四种主要类型,并就其中DR-OC型D2D通信定价提出了运营商和D2D设备的收益模型,然后仿真分析了网络中谱单价和奖励带宽对双方收益的影响。仿真结果显示运营商可以通过调整奖励带宽来协调双方收益以激励更多的用户参与到D2D通信。     

Location‐based distributed caching for device‐to‐device communications underlaying cellular networks

Device‐to‐device (D2D) communications have been viewed as a promising data offloading solution in cellular networks because of the explosive growth of multimedia applications. Because of the nature of distributed device location, distributed caching becomes an important function of D2D communications. By taking advantage of the caching capacity of the device, in this work, we explore the device storage and file frequent reuse to realize distributed content dissemination, that is, storing contents in mobile devices (named helpers). Specifically, we first investigate the average and lower bound of helper amount by dividing the network into small areas where the nodes are within each other's communication radius. Then, optimal helper amount is derived based on average helper amount and network topology. Subsequently, a location‐based distributed helper selection scheme for distributed caching is proposed based on the given optimal helper amount. In particular, nodes are selected as helpers according to their locations and degrees, and contents are placed in the manner for maximizing total user utility. Extensive simulation results demonstrate the factors that affect the optimal helper amount and the total user utility. Copyright © 2015 John Wiley & Sons, Ltd.