基于动态反馈与功率分配的干扰对齐方法

在多用户MIMO系统中,信道状态的精确性严重影响干扰对齐技术的性能。该文针对信道状态信息(CSI)有限反馈导致的干扰泄露问题,提出一种基于动态反馈与功率分配的干扰对齐方法。首先从理论上分析了系统和速率与信道状态反馈比特分配和功率分配之间的关系,得到了在动态反馈和功率分配条件下系统和速率的解析表达式;在此基础上,以系统容量提升为目标,对反馈比特分配和功率分配优化问题进行建模;并根据信道的准静态特性利用库恩塔克条件(KKT)对该问题进行求解,得到功率和反馈比特分配方案。仿真结果表明,与单独考虑信道状态动态反馈条件下的干扰对齐技术相比,提出的方法能够有效减少干扰泄漏强度,提高系统和速率。     

An Iterative Interference Alignment Scheme for the SISO Interference Channel

In this paper, we propose a novel iterative interference alignment (IA) scheme for the single-input single-output (SISO) interference channel system using minimum total mean square error criterion under the individual transmitter power constraints. We show that interference alignment under such criterion could be realized through an iterative algorithm. The convergence of the proposed algorithm is discussed. We also proposed a robust MMSE-based iterative design with imperfect channel state information. Simulation results, compared with several existing IA schemes, have shown that the proposed method could effectively improve the BER performance of the SISO interference channel system while maintaining the same degree of freedom as Cadambe?CJafar scheme. The proposed robust MMSE-based iterative interference alignment scheme is shown to be less sensitive to channel estimation error.     

基于改进图着色的D2D资源分配和功率控制

针对蜂窝网络中D2D（Device-to-Device）用户复用蜂窝信道带来的同频干扰问题,提出了一种基于改进图着色的资源分配和功率控制算法。首先通过构建干扰图和候选集进行用户之间干扰关系建模,并定义指数型累积因子改进图着色算法,为D2D用户分配蜂窝信道;再采用基于信干噪比的闭环功率控制算法动态调整D2D用户发射功率,减小由于信道复用产生的干扰。仿真结果表明,与现有算法相比,所提算法能够有效提升系统吞吐量和D2D用户接入率,实现信道资源的合理分配。     

Opportunistic interference management: a new approach for multiantenna downlink cellular networks

A new approach for multiantenna broadcast channels in cellular networks based on multiuser diversity concept is introduced. The technique called opportunistic interference management achieves dirty paper coding capacity asymptotically with minimum feedback required. When there are K antennas at the base station with M mobile users in the cell, the proposed technique only requires K integer numbers related to channel state information between mobile users and base station. The encoding and decoding complexity of this scheme is the same as that of point‐to‐point communications, which makes the implementation of this technique easy. An antenna selection scheme is proposed at the base station to reduce the minimum required mobile users significantly at the expense of reasonable increase in feedback. In order to guarantee fairness, a new algorithm is presented that incorporates opportunistic interference management into existing Global System for Mobile communications (GSM) standard. Copyright © 2014 John Wiley & Sons, Ltd.     

Joint channel selection and power control for video streaming over D2D communications based cognitive radio networks

A joint channel selection and power control scheme is developed for video streaming in device-to-device (D2D) communications based cognitive radio networks. In particular, physical queue and virtual queue models by applying ‘M/G/1 queue ’and ‘M/G/1 queue with vacations’ theories are built up, respectively, to evaluate the delays experienced by various video traffics. Such delays play a vital role in calculating the packet loss rate for video streaming, which reflects the video distortion. Based on the distortion model, a video distortion minimization problem is formulated, subject to the rate constraint, maximum power constraint, primary users’ tolerant interference constraint, and secondary users’ minimum data rate requirement constraint. The optimization problem turns out to be a mixed integer nonlinear programming (MINLP), which is generally nondeterministic in polynomial time. A Lagrange dual method is thus employed to reformulate the video distortion minimization problem, based on which the sub-gradient algorithm is used to determine a relaxed solution. Thereafter, applying the iterative user removal yields the optimal joint channel selection and power control solution to the original MINLP problem. Extensive simulations validate our proposed scheme and demonstrate that it significantly increases the peak signal-to-noise ratio (PSNR) compared with the existing schemes.     

Resource allocation and dynamic power control for D2D communication underlaying uplink multi-cell networks

Underlaying device-to-device (D2D) communication is suggested as a promising technology for the next generation cellular networks (5G), where users in close proximity can transmit directly to one another bypassing the base station. However, when D2D communications underlay cellular networks, the potential gain from resource sharing is highly determined by how the interference is managed. In order to mitigate the resource reuse interference between D2D user equipment and cellular user equipment in a multi-cell environment, we propose a resource allocation scheme and dynamic power control for D2D communication underlaying uplink cellular network. Specifically, by introducing the fractional frequency reuse (FFR) principle into the multi-cell architecture, we divide the cellular network into inner region and outer region. Combined with resource partition method, we then formulate the optimization problem so as to maximize the total throughput. However, due to the coupled relationship between resource allocation and power control scheme, the optimization problem is NP-hard and combinational. In order to minimize the interference caused by D2D spectrum reuse, we solve the overall throughput optimization problem by dividing the original problem into two sub-problems. We first propose a heuristic resource pairing algorithm based on overall interference minimization. Then with reference to uplink fractional power control (FPC), a dynamic power control method is proposed. By introducing the interference constraint, we use a lower bound of throughput as a cost function and solve the optimal power allocation problem based on dual Lagrangian decomposition method. Simulation results demonstrate that the proposed algorithm achieves efficient performance compared with existing methods.     

一种5G异构云无线接入网络的D2D资源分配算法

为了解决设备对设备(Device-to-Device,D2D)资源共享带来的信号干扰问题,提出了一种5G异构云无线接入网络的D2D通信资源分配算法.在保证服务质量的前提下,将宏用户设备的频谱资源分配给D2D和中继用户设备,并且把资源分配问题看作一对一的匹配博弈.采用婚姻匹配理论,得到初始的匹配方案.在初始匹配的基础上,提出了一种遵循卡尔多-希克斯(Kaldor-Hicks)原则的资源交换策略,以提高系统的吞吐量.仿真结果表明,该资源分配算法收敛较快,与现有方案相比,能使系统吞吐量提升15％以上,能给系统用户带来约10％的增益,并且有较强抗信道干扰能力.     

非对称MIMO双向中继干扰信道的干扰对齐算法

针对非对称的多用户MIMO双向中继干扰信道,本文提出了一种简化的基于最大信干噪比的干扰对齐算法,给出了干扰对齐的可行性条件和干扰抑制方案,并分析了系统容量和自由度。本文算法的中继节点不必做复杂的信号处理,大大降低了整个系统的信号处理复杂度;同时,本文算法是基于最大信干噪比方案,与现有文献的中继迫零方案比较,大大提高了系统在中低信噪比时的容量;进一步,通过仿真验证表明,基于本文算法的K用户对双向中继干扰网络可以达到。      

Analysis of D2D‐pairing scheme based on Voronoi diagram in cellular networks

This paper presents a device‐to‐device (D2D)–pairing scheme based on Voronoi diagram, which establishes D2D links by the relation of transmission powers and link distances. Using the principle of stochastic geometry and channel inversion, the coverage probability is analyzed, we observe that the co‐channel interference caused by cellular networks is stable in theory, and the influence of link distance parameter is highlighted as well. According to the second‐order moment of link distance, the new metric space of D2D terminals set is constructed, in which Voronoi diagram is degenerated into Delaunay triangles set to represent the potential D2D links. In addition, on the basis of the mini‐max length criterion of Delaunay triangle, the D2D communication range–limiting algorithm is designed. Finally, the more intuitive results compared with conventional D2D communications are displayed by simulations. Owing to restraining the D2D communication range, lower co‐channel interference can be obtained. Specially, the D2D‐pairing scheme is approximate local optimal under the D2D communication range–limiting algorithm, and it can provide more fairness than greedy algorithm.     

Transmission Scheme for 2D Antenna Array MIMO Systems with Limited Feedback

Three-dimensional (3D) multiple-input multiple-output (MIMO) systems exploit spatial richness and provide another degree of freedom to transmit signals and eliminate spatial interference. Currently, however, there is no 3D codebook for two-dimensional (2D) antenna array MIMO systems with limited feedback. In this paper, based on the existing 2D codebook, we present a limited feedback and transmission scheme for 2D antenna array MIMO systems. In this scheme, the mobile station (MS) has imperfect channel knowledge, and the base station (BS) only acquires partial information relating the channel instantiation. MS must feed back two channel state information (CSI) instances, i.e., the horizontal and vertical CSIs. After receiving the two CSI instances, the BS interpolates a new vertical precoding vector using the vertical CSI. Then, the BS re-constructs a 3D beamforming vector using horizontal and vertical precoding vectors and compensates the reported horizontal channel quality indicator. System level simulation is employed, and the simulation results show that the proposed method improves the system spectral efficiency and the cell-edge SE significantly.     

Bio-inspired power control and channel allocation for cellular networks with D2D communications

With the tremendous increment of traffic in the next generation mobile networks, device to device (D2D) communication is proposed to relieve the traffic burden of the base station and improve the overall network capacity. It supports direct communications between devices and could reuse the resources of cellular users (CUs). Despite the advantages, D2D communications bring great challenges in interference management. In this paper, we study the power control and channel allocation problems in three scenarios: (1) one CU and one D2D pair; (2) one CU and multiple D2D pairs; (3) multiple CUs and multiple D2D pairs. The goal is to coordinate the mutual interferences and maximize the overall network capacity. We derive sufficient conditions to guarantee the efficiency of D2D communications in scenarios with one CU and one D2D pair. We propose the bio-inspired PSO-P power control algorithm for the scenarios with one CU and multiple D2D pairs, and the PSO-CP algorithm for the scenarios with multiple CUs and multiple D2D pairs to jointly assign channels and powers. Simulation results show that the proposed algorithms are efficient in improving the overall network capacity.

     

Deep reinforcement learning-based resource allocation for D2D communications in heterogeneous cellular networks

Device-to-Device (D2D) communication-enabled Heterogeneous Cellular Networks (HCNs) have been a promising technology for satisfying the growing demands of smart mobile devices in fifth-generation mobile networks. The introduction of Millimeter Wave (mm-wave) communications into D2D-enabled HCNs allows higher system capacity and user data rates to be achieved. However, interference among cellular and D2D links remains severe due to spectrum sharing. In this paper, to guarantee user Quality of Service (QoS) requirements and effectively manage the interference among users, we focus on investigating the joint optimization problem of mode selection and channel allocation in D2D-enabled HCNs with mm-wave and cellular bands. The optimization problem is formulated as the maximization of the system sum-rate under QoS constraints of both cellular and D2D users in HCNs. To solve it, a distributed multiagent deep Q-network algorithm is proposed, where the reward function is redefined according to the optimization objective. In addition, to reduce signaling overhead, a partial information sharing strategy that does not observe global information is proposed for D2D agents to select the optimal mode and channel through learning. Simulation results illustrate that the proposed joint optimization algorithm possesses good convergence and achieves better system performance compared with other existing schemes.     

互信息量最大化和低复杂度的全双工中继网络自干扰消除和干扰对齐算法

该文针对多用户全双工中继干扰信道,同时考虑全双工中继自干扰消除及用户端干扰消除问题。首先,提出了基于最大化全局互信息量的自干扰消除和干扰对齐算法,并具体给出了自干扰消除矩阵的具体求解算法和方案。进一步,给出了信号对齐和干扰抑制的可行性条件,并分析了系统的互信息量和所受干扰噪声功率,以及系统的自由度。理论分析和仿真结果显示,与现有的典型全双工中继方案相比,该文算法可以提高系统互信息量和自由度,并有较低误码率;另外,该文算法的中继只需进行简单的功率约束,不需做复杂的信号处理,降低了整个系统的信号处理复杂度。     

Interference alignment based on optimizing bit allocation with limited feedback in interfering MIMO-MAC networks

A novel limited feedback for interference alignment algorithm was proposed based on the disadvantages of traditional limited feedback interference alignment schemes for MIMO uplink.Unlike the traditional linear interference alignment,an iterative scheme was presented.The pre-coder was designed through maximizing the target signal to the interference leakage and noise ratio,and interference suppression matrix was designed by maximizing the signal to interference plus noise ratio for each data stream,which can come over rate loss in low SNR.In addition,the bit allocation of traditional limited feedback schemes were based on the mean of interference leakage,which were not perfect and make the total number of the effective bits less than the bits provided by system.Thus,a novel bit allocation scheme was provided that improving bit utilize and decreasing quantization error.Theoretical analysis and simulation experiments show that compare to the existed classical algorithms,the algorithm was a stepwise enhancement of signal quality for iterative search in perfect CSI which was better than linear algorithm and has a larger space with no need for strictly align interference in limited feedback CSI which reduces the influence of quantization error more.The effective bit distribution and bit utilization are improved by bit allocation,resulting in improved performance in limited feedback.     

基于用户中断概率的D2D通信干扰协调与资源分配

在LTE系统中引入设备直传(D2D)通信技术,会因为D2D用户复用蜂窝用户资源进行通信而产生同频干扰.在现有的干扰协调与资源分配研究中,都需要基站获取各个通信链路的信道状态信息(CSI),但这样无疑会增加基站的信令负担.为减小干扰与基站的信令负担,提出了一种基于用户中断概率的干扰协调与资源分配算法,首先在保证蜂窝用户正常通信的情况下,通过限制D2D用户到基站间的距离来降低干扰;其次通过遍历所有蜂窝用户的频谱资源,选择能使D2D用户的总中断概率最低的频谱资源进行复用.仿真结果表明,所提算法能够在保证蜂窝用户正常通信的情况下,明显降低D2D用户的平均中断概率,同时还能够降低基站信令负担.     

Frequency resource allocation strategy with QoS support in hybrid cellular and Device‐to‐Device networks

Hybrid networks, comprising a conventional cellular network overlaid with Device‐to‐Device (D2D), offer efficient way to improve system throughput. In this paper, a novel orthogonal frequency‐division multiple access channel‐assignment method is proposed for hybrid network. The proposed approach is optimal in terms of throughput and is subjected to a sensible QoS requirement, which guarantees that macrocell and D2D achieve a prescribed data rate and outage probability, respectively. Our solution consists of two phases. In the first phase, the minimum sub‐channels are allocated to the macrocell to satisfy their data rate requirements. This problem is mapped to the 0‐1 Knapsack Problem and solved by integer programming based Lagrange dual approach. In the second phase, the redundant sub‐channels are allocated to D2D pairs to maximize the throughput of D2D networks. An interference management scheme is proposed to guarantee the outage probability of D2D communications. A cluster is taken as the unit for frequency reuse among D2D pairs. The problem of clustering is mapped to the MAX k‐CUT problem in graph theory and is solved by graph‐based heuristic algorithm. Extensive simulations demonstrate the superior performance of the proposed solution compared with the existing scheme. Copyright © 2014 John Wiley & Sons, Ltd.     

Secure opportunistic access control in D2D-enabled cellular network

The mutual interference between cellular links and D2D links can bring the secrecy gain to cellular users in D2D-enable cellular networks.To make full use of them,a cooperative secrecy transmission scheme was proposed based on wireless channels.The channel direction information and gains depict the interference from D2D links to cellular links and other D2D links in the proposed scheme.Firstly,only the D2D users which meet the limited interference conditions were accessed to cellular networks to ensure their reliable communications.It was assumed that legitimate users and eavesdroppers were independent two-dimensional homogeneous Poisson point processes (PPP) distribution.Then the security outage probability (SOP) was derived for cellular users and the connection outage probability (COP) for D2D users,and the impacts of interference thresholds were discussed on their performances.Next,an optimization model was given to minimize D2D users’ COP while ensuring the secrecy performance requirements of cellular users,thus achieving the optimal performance.Finally,simulation results verify the validity of the proposed scheme.     

SWIPT-D2D通信中基于深度强化学习的资源分配

针对信道状态信息未知SWIPT-D2D((Simultaneous Wireless Information and Power Transfer Device to Device)无线通信网络环境下设备间信号干扰以及设备能量损耗问题,提出通过使用近端策略优化(Proximal Policy Optimization, PPO)算法,在满足蜂窝用户通信质量要求的前提下同时对D2D用户的资源块、发射功率以及功率分割比三部分进行联合优化。仿真结果表明,所提算法相比于其他算法能够为D2D用户制定更好的资源分配方案,在保证蜂窝用户保持较高通信速率的同时使D2D用户获得更高的能效。同时,当环境中用户数量增加时,所提算法相比于Dueling Double DQN(Deep Q-Network)以及DQN算法,D2D能效分别平均提高了15.95%和23.59%,当通信网络规模变大时所提算法具有更强的鲁棒性。     

Joint User Association and Interference Mitigation for D2D-Enabled Heterogeneous Cellular Networks

The heterogeneous cellular networks (HCNs) with device-to-device (D2D) communications have been a promising solution to cost-efficient delivery of high data rates. A key challenge in such D2D-enabled HCNs is how to design an effective association scheme with D2D mode selection for load balancing. Moreover, the offloaded users and D2D receivers (RXs) would suffer strong interference from BSs, especially from high-power BSs. Evidently, a good association scheme should integrate with interference mitigation. Thus, we first propose an effective resource partitioning strategy that can mitigate the interference received by offloaded users from high-power BSs and the one received by D2D RXs from BSs. Based on this, we then design a user association scheme for load balancing, which jointly considers user association and D2D mode selection to maximize network-wide utility. Considering that the formulated problem is in a nonlinear and mixted-integer form and hard to tackle, we adopt a dual decomposition method to develop an efficient distributed algorithm. Simulation results show that the proposed scheme provides a load balancing gain and a resource partitioning gain.     

无线多跳网络的自适应容量感知优化与控制技术

In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communi-cating nodes. In this paper, we present a state-based channel capacity perception scheme to provide sta-tistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wire-less multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capaci-ty, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a net-work resource and forwards the data packet by tak-ing into consideration the channel capacity deploy-ments in multi-terminal or multi-hop mesh net-works. Extensive computer simulations demonstrate that the proposed scheme can achieve better per-formance in terms of packet delivery ratio and net-work throughput compared to the existing capacity prediction schemes.