GRA Based Network Selection in Heterogeneous Wireless Networks

4G wireless networks will integrate heterogeneous technologies such as Wireless LAN and third generation (3G) cellular networks and have the capability to offer various services at any time as per user requirements, anywhere with seamless interoperability at affordable cost. One important challenge in such a heterogeneous wireless environment is to enable network selection mechanisms in order to keep the mobile users always best connected anywhere and at any time. In this paper, a multi-criteria access network selection algorithm is proposed in Worldwide Interoperability for Microwave Access–Wireless Fidelity environment, in order to facilitate the provision of high quality services and at the same time to satisfy different types of user service level agreements. Analytical hierarchy process (AHP) and grey relational analysis (GRA) methods are applying for optimal access network selection. The proposed methodology combines the AHP to decide the relative weights of criteria set according to network’s performance, as well as the GRA to rank the network alternatives. The advantages of the GRA method are that the results are based on the original data, the calculations are simple and straightforward, and finally it is one of the best methods to make decision under heterogeneous wireless network environment.     

Network Selection Based on Weight Estimation of QoS Parameters in Heterogeneous Wireless Multimedia Networks

Network selection in a heterogeneous wireless environment is a major challenge to ensue seamless mobility across different radio air interfaces. To provide the desired quality of service for a given application in a multimedia environment, different parameters, including delay, bandwidth, packet loss and cost per byte, play an important role in network selection. In this paper, we present a novel algorithm for optimal network selection. A heterogeneous environment consisting of four networks, UMTS, WLAN, GPRS and WiMAX has been considered. We propose a network selection algorithm in which weight estimation for the representative set of the network attributes is computed using entropy and technique for order preference by similarity to ideal solution approach. The numerical results show that the proposed model can be effectively implemented to select the desired network in a heterogeneous environment employing triple-play services.     

无线Mesh网络中基于链路负载估算的拥塞控制策略

针对无线Mesh网络的网络特性,提出了一种基于链路负载估算的拥塞控制策略LLECC。LLECC算法计算有效链路带宽和链路负载估算确定RED算法中的调整因子,通过调整因子调整RED算法中的参数从而实现动态的对无线网络拥塞控制。详细讨论了LLECC算法的实现过程和相关参数的计算方法,通过仿真分析验证了该算法对无线Mesh网络性能的提高。     

无线自组织网络中基于QoS保障准则的可用带宽估计

对无线自组织网络中可用带宽估计问题进行了研究,提出了在估计过程中必须将全局服务质量（QoS）保障作为可用带宽的估计准则。建立了无线自组织网络中非饱和条件下异构的分析模型,该模型能将业务流的QoS度量映射为网络参数,在此基础上设计了能提供QoS保障的可用带宽估计算法。本文所提出的估计算法将包括时延、丢包率与吞吐量在内的QoS需求不被破坏作为可用带宽估计的约束条件,克服了现有的工作将无约束的最大可达吞吐量作为可用带宽因而导致业务的QoS可能受到影响这一缺陷,从而使得估计结果更加合理与准确。仿真实验证明了分析模型与可用带宽估计算法的准确性。      

A novel modeling approach for vertical handover based on dynamic k-partite graph in heterogeneous networks

The future network world will be embedded with different generations of wireless technologies, such as 3G, 4G and 5G. At the same time, the development of new devices equipped with multiple interfaces is growing rapidly in recent years. As a consequence, the vertical handover protocol is developed in order to provide ubiquitous connectivity in the heterogeneous wireless environment. Indeed, by using this protocol, the users have opportunities to be connected to the Internet through a variety of wireless technologies at any time and anywhere. The main challenge of this protocol is how to select the best access network in terms of Quality of Service (QoS) for users. For that, many algorithms have been proposed and developed to deal with the issue in recent studies. However, all existing algorithms permit only the selection of one access network from the available networks during the vertical handover process. To cope with this problem, in this paper we propose a new approach based on k-partite graph. Firstly, we introduce k-partite graph theory to model the vertical handover problem. Secondly, the selection of the best path is performed by a robust and lightweight mechanism based on cost function and Dijkstra’s algorithm. The experimental results show that the proposed approach can achieve better performance of QoS than the existing algorithms for FTP traffic and video streaming.     

Unified routing protocol based on passive bandwidth measurement in heterogeneous WMNs

The past few years have witnessed a surge of wireless mesh networks (WMNs)‐based applications and heterogeneous WMNs are taking advantage of multiple radio interfaces to improve network performance. Although many routing protocols have been proposed for heterogeneous WMNs, most of them mainly relied on hierarchical or cluster techniques, which result in high routing overhead and performance degradation due to low utilization of wireless links. This is because only gateway nodes are aware of all the network resources. In contrast, a unified routing protocol (e.g., optimal link state routing (OLSR)), which treats the nodes and links equally, can avoid the performance bottleneck incurred by gateway nodes. However, OLSR has to pay the price for unification, that is, OLSR introduces a great amount of routing overhead for broadcasting routing message on every interface. In this paper, we propose unified routing protocol (URP), which is based on passive bandwidth measurement for heterogeneous WMNs. Firstly, we use the available bandwidth as a metric of the unification and propose a low‐cost passive available bandwidth estimation method to calculate expected transmission time that can capture the dynamics of wireless link more accurately. Secondly, based on the estimated available bandwidth, we propose a multipoint relays selection algorithm to achieve higher transmission ability and to help accelerate the routing message diffusion. Finally, instead of broadcasting routing message on all channels, nodes running URP transmit routing message on a set of selected high bandwidth channels. Results from extensive simulations show that URP helps improve the network throughput and to reduce the routing overhead compared with OLSR and hierarchical routing. Copyright © 2016 John Wiley & Sons, Ltd.     

RAT selection for a low battery mobile device for future 5G networks

The growth of wireless communication toward fifth generation will lead to the existence of number of access technologies to provide seamless connectivity and form heterogeneous network environment. Earlier, there was single access technology to run applications, but 5G will have heterogeneous network environment and provide separate network for each application. As compared with 4G, 5G will provide increase in data rate, decrease in delay, increase in quality of service, and so on because of its various enabling technologies. Therefore, for each application, selection of best access network via its enabling technology is an important task. This selection is done either at user terminal side or at network operator side by combining preferences for network attributes and network parameters. In this paper, to enjoy 5G, selection is done in a heterogeneous networks environment for enabling technologies like device‐to‐device communication, spectrum sharing, enhancing quality of experience, energy efficiency, and so on. This selection is done via optimization techniques for a fixed duration video clip that is to be transmitted from a device running low in battery. The selection environment composed of UMTS, WLAN1, and WLAN2 as available networks. The simulation results show that the network selected for each enabling technology supports various features of 5G. Also, error analysis of selection results is done using confidence interval estimate at 90%, 92%, and 95% confidence level. From results obtained, it is seen that different optimization techniques used to access network for different enabling technologies (providing 5G features) prove to be useful for future 5G network.     

基于多门限预留机制的自适应带宽分配算法

针对异构无线网络融合环境提出了一种基于多门限预留机制的自适应带宽分配算法,从而为多业务提供QoS保证。该算法采用多宿主传输机制,通过预设各个网络中不同业务的带宽分配门限,并基于各个网络中不同业务和用户的带宽分配矩阵,根据业务k支持的传输速率等级需求和网络状态的变化,将自适应带宽分配问题转化为一个动态优化问题并采用迭代方法来求解,在得到各个网络中不同业务和用户优化的带宽分配矩阵的同时,在带宽预留门限和网络容量的约束条件下实现网络实时吞吐量的最大化,以提高整个异构网络带宽的利用效率。数值仿真结果显示,所提算法能够支持满足QoS需求的传输速率等级,减小了新用户接入异构网络的阻塞概率,提高了平均用户接入率并将网络吞吐量最大提高40%。     

A new handoff management system for heterogeneous wireless access networks

In heterogeneous wireless access networks, each mobile terminal may frequently need to change its base station (BS); this change is called a ‘handoff’. BSs have static parameters, which are related to their radio access technologies (RATs); however, they also contain dynamic parameters such as load and signal quality. Therefore, the problem of handoff decision includes two subproblems of RAT selection and BS selection. In this paper, first a ‘heterogeneous handoff management system’ for gathering all different required parameters is proposed. Second, a RAT Selection algorithm based on analytic hierarchy process and a BS Selection algorithm based on data envelopment analysis are designed. Finally, by means of ‘weight restriction’ technique, we develop a method for studying the impact of RAT Selection parameters on the performance of the network. Simulation results indicate that RAT Selection parameters have significant impact on the bandwidth utilization, energy consumption and the whole satisfaction of the users in heterogeneous wireless access networks.Copyright © 2012 John Wiley & Sons, Ltd.     

A simulation study of table-driven and on-demand routing protocolsfor mobile ad hoc networks

Bandwidth and power constraints are the main concerns in current wireless networks because multihop ad hoc mobile wireless networks rely on each node in the network to act as a router and packet forwarder. This dependency places bandwidth, power, and computation demands on mobile hosts which must be taken into account when choosing the best routing protocol. In previous years, protocols that build routes based on demand have been proposed. The major goal of on-demand routing protocols is to minimize control traffic overhead. We perform a simulation and performance study on some routing protocols for ad hoc networks. The distributed Bellman-Ford (1957, 1962), a traditional table-driven routing algorithm, is simulated to evaluate its performance in multihop wireless network. In addition, two on-demand routing protocols (dynamic source routing and associativity-based routing) with distinctive route selection algorithms are simulated in a common environment to quantitatively measure and contrast their performance. The final selection of an appropriate protocol will depend on a variety of factors, which are discussed in this article     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

Sustainable Spectrum Allocation Strategy for 5G Mobile Network

These days, 5G wireless communication are being created for different modern IoT (Internet of Things) applications around the world, arising with the IoT. All things considered, it is feasible to send energy efficient innovation in a manner that advances the drawn out sustainability of networks. Next-generation heterogeneous wireless communication is composed of different base stations. In this network, sustainable spectrum allocation is required to maximize the bandwidth utilization along with a reduction in power consumption. This paper proposes an algorithm for allocating an optimized spectrum to clusters in a multi-cluster environment for sustainable 5G environment using particle swarm optimization (PSO). The proposed strategy is applicable for 3G, 4G, and 5G mobile networks. Mobile devices enter and leave the cluster randomly and stay within the cluster for an uncertain amount of time. During that period the user demands may vary. Consequently, various bandwidth allocations are required. For such cases, static allocation might result in inefficient utilization of bandwidth, wastage of power, and degrade user satisfaction. The proposed algorithm will optimize the spectrum allocated to a cluster from time to time to solve this problem and produce an optimized solution within a given deadline. PSO based proposed scalable spectrum allocation method is applicable for the different frequency range for each cluster, hence scalable from 3G telecommunication to 5G-mobile edge technology. The convergence of the strategy is analyzed. From simulation analysis, it is observed that the proposed strategy reduces power consumption by approximately 8%, 11%, and 6% in 3G, 4G, and 5G communications respectively than the existing scheme.

     

基于传输速率自适应的动态带宽分配算法

提出一种基于传输速率自适应的动态带宽分配算法,为异构无线网络中的多业务提供服务质量保证。根据所提的传输速率优先级决策模型,在传输速率QoS需求和异构网络容量约束的条件下,通过动态调整不同网络中各个移动终端所支持业务的传输速率来得到最优带宽重分配矩阵,以最大化整个异构网络的效用函数;将自适应带宽重分配问题描述为一个优化问题,采用动态优化的迭代算法自适应调节用户传输速率来进一步最大化该效用函数。理论分析和数值仿真结果表明,所提算法在给定传输速率且满足QoS需求的基础上,能够最大化网络的效用函数并减小新呼叫的阻塞概率。     

A Load-aware Scheme for Providing Heterogeneous Multimedia Broadcast/Multicast Service (Het-MBMS)

As the utilization efficiency of network resource arouse the interests of researchers, Multimedia Broadcast Multicast Service (MBMS) with its inherent nature brings mobile wireless communications enter a new era. On the other hand, Next Generation Wireless Network (NGWN) trends to integrate multiple Radio Access Technologies (RATs) to optimize the overall network performance. In case, handover performance becomes a vital indicator of mobility experience of User Equipment (UE). Contrast to conventional vertical handover, the problem we facing is how to seamlessly handover for MBMS to provide heterogeneous MBMS (Het-MBMS). In order to address this problem, this paper proposes a new functional entity called Media Independent Broadcast Multicast Service Center (MIBM-SC), by the extensions and enhancements of Broadcast/Multicast-Service Center (BM-SC) and Media Independent Information Service (MIIS). Additionally, a network selection and a cell transmission mode selection schemes are proposed. Both schemes are based on a load-aware network capacity estimation algorithm to select the best target network and the best cell transmission mode. NS-2 based simulation validates that the proposed scheme enables to provide Het-MBMS and it improves the handover performance in terms of packet loss rate, throughput, handover delay, cell load, and bandwidth usage and Peak Signal-to-Noise Ratio (PSNR). Meanwhile, the total consumption of downlink power is reduced.     

Heterogeneous Network Selection Optimization Algorithm Based on a Markov Decision Model

A network selection optimization algorithm based on the Markov decision process(MDP)is proposed so that mobile terminals can always connect to the best wireless network in a heterogeneous network environment.Considering the different types of service requirements,the MDP model and its reward function are constructed based on the quality of service(QoS)attribute parameters of the mobile users,and the network attribute weights are calculated by using the analytic hierarchy process(AHP).The network handoff decision condition is designed according to the different types of user services and the time-varying characteristics of the network,and the MDP model is solved by using the genetic algorithm and simulated annealing(GA-SA),thus,users can seamlessly switch to the network with the best long-term expected reward value.Simulation results show that the proposed algorithm has good convergence performance,and can guarantee that users with different service types will obtain satisfactory expected total reward values and have low numbers of network handoffs.     

基于边缘云计算的光纤无线网络优化设计

为了提升网络边缘数据处理能力,满足终端大带宽和低时延的要求,构建了基于边缘基础设施的云计算平台,设计了具有动态带宽调整的光纤网络模型。提出了一种基于边缘云计算的时序优化算法,并将其应用于光纤无线网络。通过OPNET软件仿真分析了时序优化算法的传输时延均值,结果显示,优化后最大时延为43.1 ms,仅为传统方法的34.2%。实验对局域网内多个终端之间的数据通信进行分析,讨论了三种算法的传输能效、光纤信道利用率及传输能耗。实验结果显示,采用时序优化算法的测试结果具有明显改善,其传输能效提升了近1倍,边缘云数据传输时延均值信道利用率提升了约6.2%,网络传输能耗均值最优。该光纤无线网络模型及其优化算法在传输时延、信道利用率以及网络能耗方面具有明显提升。其在提升光纤通信链路选择及边缘端数据交互中具有一定的优势。     

基于A3C的无线异构网络自适应视频流传输控制方法

比特率自适应（ABR）算法已经成为视频传输中研究的热点之一。然而,由于5G无线异构网络具有信道带宽波动大、不同网络间差异明显等特点,多终端协同的自适应视频流传输面临着巨大挑战。提出了一种基于深度强化学习的自适应视频流传输控制方法。首先,建立了视频流动态规划模型,对传输码率以及分流策略进行联合优化。由于该优化问题的求解依赖于精确的信道估计,这在信道状态动态变化的网络中很难实现。因此,将动态规划问题改进为强化学习任务,并采用A3C算法,动态决策视频码率和分流策略。最后,根据实测的网络数据进行仿真,与传统的优化方法相比,本文所提的方法较好地提高了用户QoE。     

Efficient Resource Allocation for Wireless Multicast

In this paper, we propose a bandwidth-efficient multicast mechanism for heterogeneous wireless networks. We reduce the bandwidth cost of an Internet protocol (IP) multicast tree by adaptively selecting the cell and the wireless technology for each mobile host to join the multicast group. Our mechanism enables more mobile hosts to cluster together and leads to the use of fewer cells to save the scarce wireless bandwidth. Besides, the paths in the multicast tree connecting to the selected cells share more common links to save the wireline bandwidth. Our mechanism supports the dynamic group membership and offers mobility of group members. Moreover, our mechanism requires no modification to the current IP multicast routing protocols. We formulate the selection of the cell and the wireless technology for each mobile host in the heterogeneous wireless networks as an optimization problem. We use integer linear programming to model the problem and show that the problem is NP-hard. To solve the problem, we propose a distributed algorithm based on Lagrangean relaxation and a network protocol based on the algorithm. The simulation results show that our mechanism can effectively save the wireless and wireline bandwidth as compared to the traditional IP multicast.     

一种环境感知的无线Mesh网络自适应QoS路径选择算法

本文针对如何改善无线多跳Mesh网络的服务质量,满足无线多媒体业务对数据传输的带宽、时延、抖动的要求等问题,研究了一种基于无线信道状态和链路质量统计的MAC层最大重传次数的自适应调整算法。该算法通过对无线Mesh网络的无线信道环境的动态感知,利用分层判断法区分无线分组丢失的主要原因是无线差错还是网络拥塞导致,实时调整MAC层的最佳重传次数,降低无线网络中的分组冲突概率。基于链路状态信息的统计和最大重传策略,提出了一种启发式的基于环境感知的QoS路由优化机制HEAOR。该算法通过动态感知底层链路状态信息,利用灰色关联分析法自适应选择最优路径,在不增加系统复杂度的基础上,减少链路误判概率,提高传输效率。NS2仿真结果表明,HEAOR算法能有效减少重路由次数,降低链路失效概率,提高网络的平均吞吐率。本文提出的方法不仅能够优化MAC层的重传,而且通过发现跨层设计的优化参数实现对路径的优化选择。      

基于混合决策值的异构无线网络选择算法

针对异构网络环境下网络选择算法中决策值归一化或模糊化中存在的问题,提出了基于混合决策值的异构无线网络接入选择算法。该算法根据用户需求建立垂直切换算法评价指标体系,在此基础上建立混合型决策矩阵和计算一级指标、二级指标的权重,TOPSIS算法选择最优的网络。仿真分析表明,该算法在网络选择的过程中能够综合备选网络的各项指标,选择最优的网络接入,同时也能够满足具有特殊需求的移动台,提高网络吞吐量或减少传输延迟时间。