Layered D2D NOMA

This paper investigates a layered power allocation(PA)non-orthogonal multiple access(NOMA)scheme for device-to-device(D2D)relaying networks,where the strategy of partial data transmission at relay nodes are adopted to improve the efficiency of resources.In addition,to satisfy different quality-of-service(QoS)requirements from multiple users,layered and grouped manners are involved.Moreover,the closed-form expressions in terms of the sum-rate(SR)and outage probability of the proposed scheme are derived for independent Rayleigh fading channels,which demonstrates our theoretical analysis.Both analytical and simulation results are provided to show the superiority of our proposed scheme compared with existing works.     

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。     

基于链路间干扰辅助的中继D2D系统安全通信方法

在包含中继节点的D2D(Device-to-Device)系统中,针对蜂窝链路与D2D链路同时受窃听的问题,提出一种基于链路间干扰辅助的中继D2D系统安全通信方法.首先,确定蜂窝链路与D2D链路上下行发送模式;然后,在基站与中继节点的发送信号中添加人工噪声,协作干扰窃听者;最后,对基站功率分配与D2D功率控制进行了优化,以实现不同类型链路间干扰辅助保障系统安全.仿真结果表明,所提出的安全通信方法在保密速率方面比SVD(Singular Value Decomposition)与ZF(Zero-Forcing)预编码方法提高了1.5bit/s/Hz.     

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.     

基于信干噪比的D2D通信功率控制与资源分配

为了优化长期演进(LTE)系统引入设备直传(D2D)通信后带来的同频干扰、系统边缘用户性能恶化问题,提出一种基于信干噪比(SINR)的多小区D2D通信资源分配方案,通过调整信干噪比阈值将部分蜂窝用户(CU)转化为D2D用户并释放频谱资源进而获得较佳的资源分配策略,同时提出一种基于小区间D2D竞争机制的配置算法有效降低小区间干扰.仿真表明,算法能够有效提升系统容量,并提升小区边缘D2D用户公平性.     

Cooperative transmission in energy harvesting-based cognitive D2D networks

A cognitive device-to-device (D2D) network with D2D transmitters (DTs) that harvest radio-frequency energy from the primary transmitters (PTs) is investigated. A novel D2D transmitter-assisted cooperative (DTAC) protocol is proposed, in which a group of DTs that have no transmission opportunity act as potential relays to improve the communications of the primary network. The outage probability of the primary networ is characterized and used to make comparisons between the direct link and the cooperative link which adopts selection combining and maximal-ratio combining (MRC) schemes at the primary receivers. The cooperative link with MRC scheme improves the outage performance of the primary network with direct link, as much as 93%. The active probability of the DTs and the outage probability are derived, and the D2D network throughput is maximized by finding an optimal transmission power for the PTs. Simulation results are provided to validate the theoretical analysis.     

Interference-aware feedback based iterative Hungarian approach to allocate multiple channels to multiple D2D pairs to maximize underlay D2D network capacity

The spectral efficiency of a cellular network can be increased significantly by allowing spatial reuse of its spectrum by an underlay device-to-device (D2D) network. In an underlay D2D network, devices in close vicinity are allowed to establish low-power direct links with little to no involvement of the base station. In order to increase the spectral efficiency and the number of devices with channel access, multiple D2D pairs may transmit in each cellular channel. Additionally, each pair can be allowed to utilize multiple channels to transmit so as to maximize the D2D network capacity. This multiple-pair multiple-channel (MPMC) strategy is quite appealing but is limited by the resultant additional aggregate interference and the inherent complexity, hence necessitating the need for a fast and reliable channel allocation scheme. This work proposes a polynomial-time iterative Hungarian assignment with feedback (IHAF) algorithm for multiple channel allocations amongst multiple D2D pairs that increases the D2D network capacity manifold while maintaining the desired minimum capacity for each cellular user.     

NOMA增强型D2D通信的资源分配算法

传统蜂窝网络中,多址接入技术起着尤为关键的作用,与正交多址（Orthogonal Multiple Access,OMA）技术相比,非正交多址（Non-Orthogonal Multiple Access,NOMA）能够支持的用户数量远远超过可用正交资源的数量,可以达到更高的频谱效率和用户公平性。因此,为提高异构蜂窝网络的整体容量,本文研究了NOMA增强型设备到设备（Device to Device,D2D）的资源分配问题,并将其分解为两个独立的子问题:信道分配和功率控制。一方面,基于Coalition博弈为D2D组分配合适的信道;另一方面,对D2D发送功率和功率分配因子依据可行解域进行联合优化,以最大化整个网络中D2D可实现速率。仿真结果表明所提算法在保证系统性能的同时,还可以有效降低计算复杂度。      

Survey of software defined D2D and V2X communication

The related D2D (device-to-device) and V2X (vehicle-to-everything) are regarded as vital components of 5G communication system,which providing alternative network services and multiple application services for cellular network.In the meanwhile,SDN (software defined networking) can improve the compatibilities and flexibilities of D2D and V2X.SD-D2D (software defined D2D communication) and SD-V2X (software defined V2X communication) technologies were reviewed.Based on their similarities and respective characteristics,their state-of-arts and architectures were reviewed accordingly,and the key technologies such as D2D location/discovery management,D2D routing control,D2D flow table management,V2V path scheduling,and V2V path recovery were analyzed.Finally,it was pointed out that the SD-D2D architecture was approaching mature and the SD-V2X framework had been preliminarily determined,the existing problems of interference management,mobile management and routing management in D2D/V2X communication could be effectively solved.Furthermore,it was also pointed out that the disconnection between the existing SD-D2D/V2X studies and the actual application needed to be overcome.     

D2D通信系统中基于QoS的分簇信道分配算法

D2D(Device-to-Device)通信作为第五代移动通信(5G, 5-generation)的关键技术之一,因其高频谱效率、低能耗等优点受到广泛关注。为了更好地满足D2D用户的服务质量(quality of service, QoS)需求,本文引入用户满意度的概念,提出了一种基于QoS的分簇信道分配算法。该算法运用图论着色方法为D2D用户分配信道,可分为三个步骤:首先构建D2D用户间的干扰图,然后在保证蜂窝用户QoS需求的情况下建立D2D用户的可用颜色列表,最后为D2D用户分簇,位于同一簇内的用户可以共享信道。仿真结果表明,本文算法可以有效提高D2D用户的满意度和系统公平性。      

Cooperative MIMO precoding for the LTE-A D2D communications

In the current deployed 4G long term evolution-advanced (LTE-A) system, it adopts the precoding matrix to reduce the effect of the channel fading and improve the system capacity. Besides, a new technique of the device to device (D2D) communication enables the mobile devices using the LTE radio spectrum directly to communicate with each other. In this paper, two precoding selection methods are proposed for the multiple input multiple output (MIMO) D2D communications. The proposed methods adopt the subset and iterative concept to complete the precoding selection. Besides, a resource selection method is also provided for the D2D transmitter to select an appropriate spectrum resource among the nearby users served by the base station. Combined the resource selection with the proposed D2D precoding selection methods, both simulations and experiments demonstrate the excellent performance of the proposed methods.     

Full Duplex DD for In-Band D2D Communication

Wireless Personal Communications - Device to device (D2D) communication is a candidate technology to ascertain the 5G wireless system. To implement the D2D communication in an in-band cellular...     

D2D communication with energy harvesting relays for disaster management

ABSTRACT

In this paper, we consider a multi-hop device-to-device (D2D) communication, which enables communication from functional area (FA), where the D2D users are placed near to base station (BS) under its coverage to non-functional area (NFA). In our proposed model, random deployment as well as certain distance-dependent deployment of D2D node is considered in NFA. In case of FA, BS is transmitting information with fixed transmit power in multi-hop D2D network. In case of NFA, a D2D node harvests energy from its preceding node, and forwards the information to the successive node. Parallel best path selection (PBPS) and immediate best path selection (IBPS) strategies are considered for FA while several cases of deployment strategies based on inter-node distance is considered for NFA to reach the final destination node. A framework has been proposed for evaluating throughput, ergodic capacity and outage probability. Energy consumption in the system has been estimated via simulation. The throughput performance, ergodic capacity and the outage probability of end-to-end link (i.e. from BS to NFA) under different system parameters are evaluated.     

Cooperative energy efficient D2D clustering in LTE-A with enhanced QoS

Device-to-device (D2D) communications in the long term evolution (LTE) Advanced (LTE-A) cellular system are investigated. The objective is to form collaborative D2D groups for transmitting/receiving data in the uplink (UL) and downlink (DL) in an energy efficient manner. The energy minimization problem using multihop D2D is formulated as a binary integer linear program. A low complexity suboptimal solution method is proposed, and shown to lead to good performance, especially in the low complexity 1-hop D2D scenario. The investigated framework is applicable to both public safety (PS) and non-PS scenarios. In addition to significant energy savings, the proposed method is shown to lead to reduced delays and enhanced quality of service (QoS), especially when real-time video transmission is considered.     

Power allocation criteria for distributed antenna systems with D2D communication

In this paper, we discuss four different optimization problems for distributed antenna systems (DAS) with and without D2D communication, respectively. The first and the third problems are maximizing spectral efficiency (SE) and energy efficiency (EE) of the DAS with D2D communication on the conditions of the minimum SE of DAS as well as D2D pair, the maximum transmit power of each remote access unit (RAU) and maximum transmit power of D2D transmitter. The second and the forth problems are maximizing SE of the DAS on the conditions of the minimum SE as well as the maximum transmit power of RAUs. We exploit the sub-gradient iteration method to obtain the optimal power allocation and summarize optimal power allocation algorithms for the first and second problems. We exploit fractional programming method to investigate the third and fourth problems and develop corresponding optimal power allocation algorithms. Simulation results demonstrate the effectiveness of the proposed power allocation algorithms and show the SE and EE of the DAS by using D2D communication are much better than DAS without D2D communication.     

UAV-assisted multi-hop D2D relaying for communication in large disaster area

An unmanned aerial vehicle (UAV)-assisted communication is a promising technique for enabling ground users in a non-functional area (NFA) or disaster area to communicate. All the base stations in the disaster area may be partially or fully damaged due to the natural calamity. Device-to-device (D2D) communication can be a viable solution for immediate connection between users in an NFA. We propose a UAV-assisted multi-hop D2D communication following a hybrid power-time switching (PTS) in this paper. Moreover, a D2D user of a cluster can communicate with another D2D user in a different cluster through UAVs. However, D2D users can harvest energy from their respective ad hoc energy stations and forward the information to the nearby D2D user following a hybrid PTS-based strategy. We propose a time frame for the same and show a node-based energy harvesting strategy. The expressions of outage probability, throughput, end-to-end energy consumption, and energy efficiency are developed for the Rician and Nakagami-m faded channel. The impact of several network parameters such as energy harvesting factor, energy harvesting efficiency, and fading parameter on the network performance is also indicated.     

Resource allocation for NOMA based D2D underlaid cellular networks

This paper puts forward a user clustering and power allocation algorithm for non-orthogonal multiple access (NOMA) based device-to-device (D2D) cellular system. Firstly, an optimization problem aimed at maximizing the sum-rate of the system is constructed. Since the optimization problem is a mixed-integer non-convex optimization, it is decomposed into two subproblems, namely user clustering and power allocation subproblem. In the subproblem of user clustering, the clustering algorithms of cellular user and D2D pair are proposed respectively. In the power allocation subproblem, the gradient assisted binary search (GABS) algorithm and logarithmic approximation in successive convex approximation (SCA) are used to optimize the power of subchannel (SC) and D2D transmitted power respectively. Finally, an efficient joint iterative algorithm is proposed for the original mixed inter non-convex non-deterministic polynomial (NP)-hard problem. The simulation results show that the proposed algorithm can effectively improve the total system rate and the larger the ratio of cellular users (CUs) to total users, the larger the total system rate.     

异构网络中基于能效优化的D2D资源分配机制

针对异构网络中D2D通信复用蜂窝用户频谱时存在的频谱分配问题,该文提出一种基于改进离散鸽群优化(PIO)算法的D2D通信资源分配机制。通过设置信干噪比(SINR)门限值来保证用户的通信服务质量(QoS),采用功率控制算法为用户设置发射功率,使用基于运动权值的二进制离散鸽群优化(MWBPIO)算法为D2D用户进行资源分配,并将D2D通信技术与中继技术进行有效结合,为边缘用户建立D2D中继链路,保证边缘用户的通信质量,最大化系统性能目标。仿真结果表明,该方案有效抑制了异构通信系统中引入D2D用户后导致的干扰问题,提高了边缘用户的通信质量和系统的频谱利用率以及系统的能效。     

Recursive pruning of the 2D DFT with 3D signal processingapplications

A recursively pruned radix-(2×2) two-dimensional (2D) fast Fourier transform (FFT) algorithm is proposed to reduce the number of operations involved in the calculation of the 2D discrete Fourier transform (DFT). It is able to compute input and output data points having multiple and possibly irregularly shaped (nonsquare) regions of support. The computational performance of the recursively pruned radix-(2×2) 2D FFT algorithm is compared with that of pruning algorithms based on the one-dimensional (1D) FFT. The former is shown to yield significant computational savings when employed in the combined 2D DFT/1D linear difference equation filter method to enhance three-dimensional spatially planar image sequences, and when employed in the MixeD moving object detection and trajectory estimation algorithm     

Energy efficient power allocation for co-located antenna systems with D2D communication

This paper investigates the energy efficient resource allocation when adding dedicated device-to-device (D2D) communication in the co-located antenna systems (CAS). We consider the user equipments (UEs) are changing over time and the appropriate potential UEs to form D2D pairs are varying with time. Our optimization objective is to maximize the system’s energy efficiency (EE) with the constraints of the maximum transmit power of UEs and D2D pairs in different total power consumption models. Firstly, an algorithm is developed to choose appropriate potential UEs to form D2D pairs in this paper. Then we exploit fractional programming method to obtain optimal energy efficient power allocation solutions. Simulation results are provided to demonstrate the effectiveness of the developed D2D pairs choosing algorithm and the power allocation algorithm.