基于安全中断概率的D2D安全接入策略

针对D2D蜂窝系统通信安全性受资源限制的问题,考虑到蜂窝链路和D2D链路的同频干扰能够为两者带来安全增益,基于此,提出一种基于安全中断概率的D2D用户接入策略。首先理论分析了蜂窝用户和D2D用户的安全中断概率,并给出了基于安全中断概率最小化的D2D用户功率优化算法。在上述分析的基础上,选择安全中断概率最小的D2D用户接入复用蜂窝用户的无线资源,同时提高D2D通信链路和蜂窝上行链路的安全性。最后,仿真结果证明了所提算法的有效性。     

A non-iterative resource allocation strategy for device-to-device communications in underlaying cellular networks

We develop a joint spectrum sharing and power control strategy to increase the admissible number of device-to-device (D2D) links in an underlaying cellular network while guaranteeing the quality-of-service (QoS) of both D2D links and cellular users (CUs). The proposed spectrum sharing algorithm, termed as interference-filling (IF), examines whether the SINR requirements of all the existing CUs and D2D users can be met if a new D2D pair is admitted. In the sequel, two power control schemes are proposed to check the resultant interference level and increase the transmit power of the admitted D2D pairs group-by-group to further improve the system throughput. IF algorithm is based on the ordering statistics of the interference amounts from D2D transmitters to CUs, thus neither grid searching nor iteration is needed. Furthermore, the two proposed power control schemes are in closed-forms. These two favorable properties make the proposed strategy cost-effective and computationally efficient. Numerical results show the effect of the proposed IF and power control schemes in term of admissible D2D pairs and system sum rate.     

D2D通信中基于粒子群优化的能效最大化策略

5G中终端的能量消耗和频谱资源问题日益严重,在终端直通技术(D2D)中尤为突出.为了提高D2D对用户(DP)的能效和资源利用率,提出了一种基于粒子群算法的联合功率控制和资源分配策略.以最大化D2 D链路总能效为目标,将构造的资源分配矩阵和功率分配矩阵作为粒子的位置,依照蜂窝用户(CU)和DP服务质量的约束来修正粒子位置和速度,使之适合于原分式规划问题的求解,合理地提升了DP的总能效,实现了一个DP链路能复用多个CU资源.仿真结果表明,所提算法不仅使能效显著提升,而且使资源利用率提高了80%.     

Optimal resource allocation for heterogeneous traffic in multipath networks

Multipath networks allow each source to send packets from it to its destination over multiple paths, which increases the available bandwidth and throughput for source‐destination pairs. Recently, a variety of flow control schemes have been presented for multipath networks to achieve optimal resource allocation. Unfortunately, much of the investigation focused on elastic traffic with controllable packet injection rates. Networks have witnessed an increase in real‐time traffic (voice and video), which are inelastic. We consider resource allocation for heterogeneous traffic in multipath networks and formulate an optimization problem, which is intrinsically difficult nonconvex. In order to address the aforementioned issue and obtain the optimum, we approximate an equivalent problem of the original optimization problem to a strictly convex problem and present a primal‐dual resource allocation algorithm for the approximation problem, which converges to an optimal solution satisfying the Karush‐Kuhn‐Tucker conditions of the original problem. We evaluate its convergence performance through theoretical analysis and illustrate it with numerical examples. Copyright © 2014 John Wiley & Sons, Ltd.     

Access probability optimization for streaming media transmission in heterogeneous cellular networks

FemtoCaching technology, aiming at maximizing the access probability of streaming media transmission in heterogeneous cellular networks, is investigated in this paper. Firstly, five kinds of streaming media deployment schemes are proposed based on the network topology and the relationship between users and streaming media. Secondly, a matching algorithm for adaptive streaming media deployment is proposed, where the FemtoCaching can be adjusted dynamically. Thirdly, a joint problem is formulated combined with the channel assignment, the power allocation, and the caching deployment. To address this problem, we propose a joint optimization algorithm combining matching algorithm and genetic algorithm to maximize the access probability of streaming media transmission. Simulation experiments demonstrate that: (1) the average access probability of all users accessing streaming media in the network based on the proposed algorithm compared with recent works can be greatly improved, and (2) the performance increases with increasing the number of channels and the storage capacity of micro base stations, but decreases with increasing the number of users.

     

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.     

QoS-guaranteed transmission mode selection for efficient resource utilization in multi-hop cellular networks

This paper considers the problem of efficient usage of subcarriers in downlink Orthogonal Frequency-Division Multiple Access (OFDMA) multi-hop cellular networks. Multi-hop transmission can either save or waste subcarriers depending on quality of service (QoS) requirements, interference from other cells, and the location of a given mobile station (MS). Preventing unnecessary usage of multi-hop transmission requires the use of a transmission mode selection (TMS) scheme, and we propose two types of TMS in this paper. The first of these is distance-based TMS (TMS-D), which determines the transmission mode based on the MS?s location, and the second is subcarrier-based TMS (TMS-S), which selects whichever transmission mode uses fewer subcarriers. Numerical results on blocking probability demonstrate that TMS improves overall subcarrier usage efficiency, meaning that more MSs can be supported with low blocking probability within a cell. Furthermore, the performance of TMSS, even given its higher complexity, is shown to be superior to that of TMS-D.     

ON THE STABILITY OF CELLULAR NEURAL NETWORKS WITH FEEDBACK MODE

Cellular Neural Networks (CNN) with feedback mode and M×N cells are equivalent to a network which possesses 2M×N cells, a neighborhood with mirror-like structure, space-variant templates and without feedback as well as without input templates. The stability of the CNN with feedback mode and transformations with the neighborhood of mirror-like structure are discussed.     

异构蜂窝网络中用户关联与基站功率的协同优化

为实现异构蜂窝网络中宏基站和小基站之间的负载均衡,提出了一种基于效用函数最大化模型的用户关联机制和基站功率控制的协同优化方案.通过迭代算法求解该协同优化问题,首先在基站功率固定的情况下求得最佳用户关联策略,然后在所得的用户关联策略基础上通过Zoutendijk可行方向法求得基站最佳功率.通过协同优化获得的用户关联策略和基站功率控制实现了基站之间的负载均衡,通过降低宏基站功率和关闭闲置小基站降低了基站的能耗.仿真实验表明,所提方案和不实施功率控制的用户关联策略相比,实现了宏基站与小基站之间的负载均衡,降低了宏基站对小基站用户的干扰,提升了小基站用户的信号干扰噪声比,用户速率中位值提高了20％.     

异构蜂窝网络中分层任务卸载：建模与优化

为提高计算任务卸载的效率,提出了一种基于D2D通信、移动边缘计算和云计算的分层任务卸载框架,并引入D2D协作中继技术辅助用户接入远端计算资源。针对所提任务卸载框架在多用户场景中可能存在上行通信拥塞、边缘计算资源受限、D2D复用干扰和云计算回程时延等问题,设计了一种基于博弈论的卸载调度和负载均衡方案,充分利用了所提任务卸载框架中各层计算和通信资源。仿真结果表明,所提方案能够有效降低端到端时延和卸载能耗,并在资源受限的条件下具有良好的稳定性。     

Resource allocation and power control for underlay device-to-device communication in fractional frequency reuse cellular networks

The current state of device-to-device (D2D) communication in the presence of cellular network addresses two major challenges of interference as well as throughput inadequacy. Specifically, a D2D communication underlaying fractional frequency reuse (FFR) cellular network exhibits rather high interferences due to higher occurrence of band crossing within a shared spectrum. However, due to the considerable impact of D2D communications on spectral efficiency and system capacity, the remedy for those issues may include efficient techniques of interference mitigation and average spectral efficiency maximization. In this paper, we propose a resource block (RB) allocation scheme to reduce the co-channel interference by providing and maintaining adequate distance between D2D user equipment (DUE) and cellular user equipment (CUE), and between the macrocell base station and DUEs that are using the same RB. In the proposed scheme, we initially introduce a plan with one omnidirectional and three directional antennas be used to serve the CUE in the inner and outer regions of the FFR cell, respectively. In addition, DUE in each region uses the RBs that are orthogonal to those used by CUE. It is shown that by using two different ranges for inner region of cellular and D2D communication, the overall performance is improved. Furthermore, we formulate an optimization problem for maximizing average spectral efficiency while guaranteeing CUE signal-to-interference-plus-noise-ratio and achieve efficient solutions to the different average spectral efficiency maximization problems. The results demonstrate the efficiency of the proposed scheme. In addition, it is shown that significant improvement in system spectral efficiency is obtained through the optimization of DUE power. That is, the achieved throughput is much higher than that of the random resource allocation and 1.5–2 times of the previous works.     

设备直通中面向能效与用户公平性折中的联合功率控制和调度方案

设备直通通信作为5G系统中的关键技术之一,可显著提高系统侧和用户侧性能。但目前已有研究主要侧重优化前者。基于此,提出了一种联合时频域调度和功率控制机制,以实现系统能效与用户公平性间的折中。该机制包括功率控制和时频域调度两部分,其中,功率控制最大化D2D用户能效值;时频域调度确定任意时刻应接入的D2D用户数以及各自的信道资源。此外,借助比例公平思想动态更新匹配所需效用值。通过仿真,验证了所提联合机制的优势,并观察了系统整体能效和用户公平间的折中关系。     

Long-term rate control for concurrent multipath real-time video transmission in heterogeneous wireless networks

Concurrent multipath transmission provides an effective solution for streaming high-quality mobile videos in heterogeneous wireless networks. Rate control is commonly adopted in multimedia communication systems to fully utilize the available network bandwidth. This paper proposes a novel rate control for concurrent multipath video transmission. The existing rate control algorithms mainly adapt bit rate in the short-term pattern, i.e., without considering the long-term video transmission quality. We propose a long-term rate control scheme that takes into account the status of both the transmission buffer and video frames. First, a mathematical model is developed to formulate the non-convex problem of long-term quality maximization. Second, we develop a dynamic programming solution for online encoding bit rate control based on buffer status. The performance evaluation is conducted in a real test bed over LTE and Wi-Fi networks. Experimental results demonstrate that the proposed long-term rate control scheme achieves appreciable improvements over the short-term rate control schemes in terms of video quality and delay performance.     

Optimal scheduling of coordinated multipoint transmissions in cellular networks

In this paper, we study the optimal scheduling problem in coordinated multipoint (CoMP) transmission–based cellular networks. We consider joint transmission and coordinated scheduling together in CoMP transmission–based cellular networks and develop an optimization framework to compute the optimal max‐min throughput and the optimal scheduling of the transmissions to the users. The optimization problem is found to be a complex linear program with number of variables in for a cellular network of N users and K cells. We solve the optimization problem for several network instances using an optimization tool. The numerical results show that the optimal CoMP transmission provides a significant throughput gain over a traditional transmission. We find that in optimal scheduling the fraction time of coordinated scheduling is higher than that of joint transmission. To solve the optimization problem without any optimization tool, we propose a heuristic algorithm. The performance of the heuristic algorithm is evaluated and found to be provided throughput around 97% of the optimal throughput. Further, we extend the optimization framework to study joint scheduling and power allocation (JSPA) problem in CoMP transmission–based cellular networks. We numerically solve the JSPA problem for the network instances and demonstrate that the optimal power allocation at the base stations is not binary for a significant fraction of time of scheduling. However, the gain in max‐min throughput by the optimal JSPA technique over the optimal scheduling technique is not significant.     

A virtualized resource management scheme for heterogeneous cellular networks

Because of random deployment patterns of femtocells, interference scenarios in a heterogeneous cellular network can be very complicated because of its changing network topology. Especially when each eNodeB occupies a fixed bandwidth, interference management becomes much more difficult. The benefit of dynamic management for local resource optimation is limited. Recently, resource virtualization has been proposed as a dynamic resource management scheme to optimize network performance. In fact, resource virtualization is viewed as a more flexible model, in which mobile network service providers can control physical resources in a global scope. This paper presents a joint resource virtualization and allocation scheme for its applications in heterogeneous macro‐femto‐cellular networks. The proposed scheme involves two major processes. First, it virtualizes physical resources as logical resources. Second, it carries out logical resource allocation optimization globally and aggregates logical and physical resources for resource allocation. The proposed scheme takes into account spectrum reuse and frequency domain interference jointly in order to achieve a high spectral efficiency and provide rate‐on‐demand services to all users. Simulation results demonstrate the effectiveness of the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

Optimal resource allocation solutions for heterogeneous cognitive radio networks

Cognitive radio networks (CRN) are currently gaining immense recognition as the most-likely next-generation wireless communication paradigm, because of their enticing promise of mitigating the spectrum scarcity and/or underutilisation challenge. Indisputably, for this promise to ever materialise, CRN must of necessity devise appropriate mechanisms to judiciously allocate their rather scarce or limited resources (spectrum and others) among their numerous users. ‘Resource allocation (RA) in CRN', which essentially describes mechanisms that can effectively and optimally carry out such allocation, so as to achieve the utmost for the network, has therefore recently become an important research focus. However, in most research works on RA in CRN, a highly significant factor that describes a more realistic and practical consideration of CRN has been ignored (or only partially explored), i.e., the aspect of the heterogeneity of CRN. To address this important aspect, in this paper, RA models that incorporate the most essential concepts of heterogeneity, as applicable to CRN, are developed and the imports of such inclusion in the overall networking are investigated. Furthermore, to fully explore the relevance and implications of the various heterogeneous classifications to the RA formulations, weights are attached to the different classes and their effects on the network performance are studied. In solving the developed complex RA problems for heterogeneous CRN, a solution approach that examines and exploits the structure of the problem in achieving a less-complex reformulation, is extensively employed. This approach, as the results presented show, makes it possible to obtain optimal solutions to the rather difficult RA problems of heterogeneous CRN.     

On the performance of packet-switched cellular networks for wireless data communications

Cellular frequency reuse is known to be an efficient method to allow many wireless telephone subscribers to share the same frequency band. However, for wireless data and multi-media communications optimum cell layouts differ essentially from typical solutions for telephone systems. We argue that wireless radio systems for bursty message traffic preferably use the entire bandwidth in each cell. Packet queuing delays are derived for a network with multipath fading channels, shadowing, path loss and discontinuously transmitting base stations. Interference between cells can be reduced by appropriately scheduling transmissions or by spatial collision resolution.Portions of this paper have been presented at the IEEE International Conferences on Personal Indoor Mobile Radio Communications (PIMRC) of 1993 in Yokohama and 1994 in The Hague.     

Estimation of performance measures for product form cellular mobile communications networks

Telecommunication Systems - This paper investigates cellular mobile communications networks. The purpose of the paper is twofold. First, it is shown that the restrictive assumption of reversible...     

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.     

Outage and energy efficiency analysis for cognitive based heterogeneous cellular networks

Cognitive radio and small cells are the promising techniques to minimize energy consumption and satisfy the exponentially increasing data rates for the heterogeneous cellular network (HCN). In this paper, a theoretical framework is developed to calculate the outage probability of the HCN based on the opportunistic utilization of the traditional cellular bandwidth and television white space (TVWS) for the cognitive femto base stations. This work investigates overlay, underlay, mixed overlay-underlay based two tiers cognitive HCN. It also investigates the impact of the TVWS in the overlay-TVWS mixed spectrum sharing technique (SST). Tools from stochastic geometry are used to model cognitive HCN. Furthermore, the tier selection probability, average ergodic rate, area spectral efficiency (ASE), and energy efficiency (EE) of the HCN are also calculated for different SSTs. Numerical results show that mixed SST achieves a significant reduction in tier outage probability and total outage probability as compared to underlay and overlay techniques alone. It is also demonstrated that compared to the traditional single tier network, cognitive based HCN can improve the total ASE and EE of the order of \(10^{2}\) and 10, respectively.