A tutorial survey of topics in wireless networking: Part II

This is the second part of the survey of recent and emerging topics in wireless networking. We provide an overview of the area of wireless networking as that of dealing with problems of resource allocation so that the various connections that utilise the network achieve their desired performance objectives. In Part I we provided a taxonomy of wireless networks as they have been deployed. We then provided a quick survey of the main issues in the wireless ‘physical’ layer. We then discussed some resource allocation formulations in CDMA (code division multiple access) cellular networks and OFDMA (orthogonal frequency division multiple access) networks. In this part we begin with a discussion of random access wireless networks. We first provide an overview of the evolution of random access networks from Aloha to the currently popular 802·11 (Wi-Fi) networks. We then analyse the performance of the 802· 11 random access protocol. We briefly discuss the problem of optimal association of nodes to Wi-Fi access points. Next, we consider topics in ad hoc multihop wireless networks. We first discuss topology and cross layer control. For the latter, we describe the important maximum weight link scheduling algorithm. The connectivity and capacity of randomly deployed networks are then analysed. Finally, we provide an overview of the technical issues in the emerging area of wireless sensor networks.     

Topological properties of random wireless networks

Wireless networks in which the node locations are random are best modelled as random geometric graphs (RGGs). In addition to their extensive application in the modelling of wireless networks, RGGs find many new applications and are being studied in their own right. In this paper we first provide a brief introduction to the issues of interest in random wireless networks. We then discuss some recent results for one-dimensional networks with the nodes distributed uniformly in (0,z). We then discuss some asymptotic results for networks in higher dimensions when the nodes are distributed in a finite volume. Finally we discuss some recent generalisations in considering non uniform transmission ranges and non uniform node distributions. An annotated bibliography of some of the recent literature is also provided.     

WiFi6 Dynamic Channel Optimization Method for Fault Tolerance in Power Communication Network

As the scale of power networks has expanded, the demand for multi-service transmission has gradually increased. The emergence of WiFi6 has improved the transmission efficiency and resource utilization of wireless networks. However, it still cannot cope with situations such as wireless access point (AP) failure. To solve this problem, this paper combines orthogonal frequency division multiple access (OFDMA) technology and dynamic channel optimization technology to design a fault-tolerant WiFi6 dynamic resource optimization method for achieving high quality wireless services in a wirelessly covered network even when an AP fails. First, under the premise of AP layout with strong coverage over the whole area, a faulty AP determination method based on beacon frames (BF) is designed. Then, the maximum signal-to-interference ratio (SINR) is used as the principle to select AP reconnection for the affected users. Finally, this paper designs a dynamic access selection model (DASM) for service frames of power Internet of Things (IoTs) and a scheduling access optimization model (SAO-MF) based on multi-frame transmission, which enables access optimization for differentiated services. For the above mechanisms, a heuristic resource allocation algorithm is proposed in SAO-MF. Simulation results show that the method can reduce the delay by 15% and improve the throughput by 55%, ensuring high-quality communication in power wireless networks.     

SECURITY OF VIRTUAL PRIVATE NETWORK

Virtual Private Networks(VPN) are a big part of networking because of the security tool that they use. VPN encrypts all of the data that is sent through networks. Because a lot of networks have gone wireless, the need for extremely secure networks is in high demand.VPN are definitely one of the types of networks that have help innovate wireless network security. By explaining how the various implementations of VPN help keep networks secure, we can understand the advantages and services that virtual private networks offer wireless networks.     

基于自相似流的无线Mesh网络信道分配算法

根据业务流的自相似性提出了一种新颖的信道分配算法。该算法首先根据流的自相似性,估计网络中的节点的业务量。然后,根据业务量多少确定占用信道的优先级。业务量大的节点可以优先占用信道。这样,解决了“热点”信道资源紧张的问题。同时,算法对“非热点”的吞吐量影响很小。理论分析证明,这种算法可以有效提高网络吞吐量。仿真结果表明,运用这种算法,网络的吞吐量比最小干扰固定信道分配算法和最小干扰混合信道分配算法可分别提高70％和40％。     

Adaptive opportunistic fair scheduling in power-controlled code division multiple access systems

The authors treat the multiuser scheduling problem for practical power-controlled code division multiple access (CDMA) systems under the opportunistic fair scheduling (OFS) framework. OFS is an important technique in wireless networks to achieve fair and efficient resource allocation. Power control is an effective resource management technique in CDMA systems. Given a certain user subset, the optimal power control scheme can be derived. Then the multiuser scheduling problem refers to the optimal user subset selection at each scheduling interval to maximise certain metric subject to some specific physical-layer constraints. The authors propose discrete stochastic approximation algorithms to adaptively select the user subset to maximise the instantaneous total throughput or a general utility. Both uplink and downlink scenarios are considered. They also consider the time-varying channels where the algorithm can track the time-varying optimal user subset. Simulation results to show the performance of the proposed algorithms in terms of the throughput/ utility maximisation, the fairness, the fast convergence and the tracking capability in time-varying environments are presented.     

Energy Efficient Ambience Awake Routing with OpenFlow Approach

A major problem in networking has always been energy consumption. Battery life is one parameter which could help improve Energy Efficiency. Existing research on wireless networking stresses on reducing signaling messages or time required for data transfer for addressing energy consumption issues. Routing or Forwarding packets in a network between the network elements like routers, switches, wireless access points, etc., is complex in conventional networks. With the advent of Software Defined Networking (SDN) for 5G network architectures, the distributed networking has embarked onto centralized networking, wherein the SDN Controller is responsible for decision making. The controller pushes its decision onto the network elements with the help of a control plane protocol termed OpenFlow. Decentralized networks have been largely in use because of their ease in physical and logically setting the administrative hierarchies. The centralized controller deals with the policy funding and the protocols used for routing procedures are designated by the decentralized controller. Ambience Awake is a location centered routing protocol deployed in the 5G network architecture with OpenFlow model. The Ambience Awake mechanism relies on the power consumption of the network elements during the packet transmission for unicast and multicast scenarios. The signalling load and the routing overhead witnessed an improvement of 30% during the routing procedure. The proposed routing mechanism run on the top of the decentralized SDN controller proves to be 19.59% more efficient than the existing routing solutions.     

Dynamic resource allocation for supporting real-time multimedia applications in IEEE 802.15.3 WPANs

The IEEE 802.15.3 medium access control (MAC) protocol is an emerging standard for high-rate wireless personal area networks (WPANs), especially for supporting high-quality real-time multimedia applications. Despite defining quality of service (QoS) signalling mechanisms for interoperability between devices, IEEE 802.15.3 does not specify resource allocation algorithms that are left to manufacturers. To guarantee the QoS of real-time variable bit rate (VBR) videos and utilise the radio resource efficiently, the authors propose a dynamic resource allocation algorithm. The proposed bandwidth allocation algorithm is based on a novel traffic predictor. Recently, the variable step-size normalised least mean square (VSSNLMS) algorithm was employed for on-line traffic prediction of VBR videos. However, the performance of the VSSNLMS algorithm significantly degrades due to the abrupt traffic variation occurring at the scene boundary. To tackle this problem, the authors design a novel traffic predictor based on a simple scene detection algorithm and the VSSNLMS algorithm. Analyses using real-life MPEG video traces indicate that the proposed traffic predictor significantly outperforms the VSSNLMS algorithm with respect to the prediction error. The performance of the proposed bandwidth allocation algorithm is also investigated by comparing several existing algorithms. Simulation results demonstrate that the proposed bandwidth allocation algorithm surpasses other mechanisms in terms of channel utilisation, buffer usage and packet loss rate.     

TWDM-PON-AN optical backhaul solution for hybrid optical wireless networks

Abstract

To improve the performance of broadband access networks Full Service Access Network selected Time and wavelength division multiplexed Passive Optical Network (TWDM-PON) as the primary solution for next-generation optical access (Next-Generation Passive Optical Networks 2 (NGPON2)). This paper reviews the recent progress in this access technology. Different possible solutions for the-next generation access are explained. Comparison of the different TWDM architectures experimentally demonstrated so far is made considering the large split, long reach and high capacity requirements of NGPON2. Major technical challenges in implementing the TWDM networks are discussed. Possible options for designing hybrid wireless–wireline architectures are explained taking care of the high bandwidth provided by the optical networks and high mobility of wireless networks. Also an integrated optical wireless architecture is suggested using TWDM-PON as an optical backhaul.     

Cross-layer adaptive resource allocation for OFDM systems with hybrid smart antennas

Orthogonal frequency division multiplex (OFDM) has become one of the most popular air-link technologies for future broadband wireless communications. To further improve its bandwidth efficiency and system performance, adaptive resource allocation and smart antenna techniques have been widely used in the OFDM system. However, the use of fully adaptive beamforming in an OFDM system significantly increases the complexity of the medium access control layer design and thus affects the implementation of adaptive resource allocation. A novel cross-layer adaptive resource allocation strategy with hybrid adaptive array and switched- beam smart antennas suitable for the OFDM systems has been proposed. With the help of different smart antennas schemes based on different users' quality of service requirements, the strategy effectively reduces the complexity of adaptive resource allocation in an OFDM system, while still maintaining a satisfactory system performance.     

Global network structure of dominance hierarchy of ant workers

Dominance hierarchy among animals is widespread in various species and believed to serve to regulate resource allocation within an animal group. Unlike small groups, however, detection and quantification of linear hierarchy in large groups of animals are a difficult task. Here, we analyse aggression-based dominance hierarchies formed by worker ants in Diacamma sp. as large directed networks. We show that the observed dominance networks are perfect or approximate directed acyclic graphs, which are consistent with perfect linear hierarchy. The observed networks are also sparse and random but significantly different from networks generated through thinning of the perfect linear tournament (i.e. all individuals are linearly ranked and dominance relationship exists between every pair of individuals). These results pertain to global structure of the networks, which contrasts with the previous studies inspecting frequencies of different types of triads. In addition, the distribution of the out-degree (i.e. number of workers that the focal worker attacks), not in-degree (i.e. number of workers that attack the focal worker), of each observed network is right-skewed. Those having excessively large out-degrees are located near the top, but not the top, of the hierarchy. We also discuss evolutionary implications of the discovered properties of dominance networks.     

基于FDMA系统的两跳中继网络的资源分配

首先介绍了一种可用于两跳中继网络的时分模式帧结构,然后基于该帧结构提出了一种资源分配算法.该算法包括两个步骤:第一个步骤是第一个时隙上的动态资源分配,第二个步骤是基站与中继站之间的最优化功率分配.两跳中继网络中下行存在三种链路:"基站-中继"链路、"基站-用户"链路和"中继-用户"链路,在系统资源有限的条件下,通过所提算法为这三种链路分配相应的带宽和功率,可以使得系统的吞吐量最大.仿真结果表明所提算法能够有效地提高系统的吞吐量.     

Resource Allocation in Edge-Computing Based Wireless Networks Based on Differential Game and Feedback Control

In this paper, we have proposed a differential game model to optimally solve the resource allocation problems in the edge-computing based wireless networks. In the proposed model, a wireless network with one cloud-computing center (CC) and lots of edge services providers (ESPs) is investigated. In order to provide users with higher services quality, the ESPs in the proposed wireless network should lease the computing resources from the CC and the CC can allocate its idle cloud computing resource to the ESPs. We will try to optimally allocate the edge computing resources between the ESPs and CC using the differential game and feedback control. Based on the proposed model, the ESPs can choose the amount of computing resources from the CC using feedback control, which is affected by the unit price of computing resources controlled by the CC. In the simulation part, the optimal allocated resources for users’ services are obtained based on the Nash equilibrium of the proposed differential game. The effectiveness and correctness of the proposed scheme is also verified through the numerical simulations and results.     

Does size still matter? How micro firms and SMEs vary in network learning

ABSTRACT

How can geographically constrained Micro firms and SMEs in emerging markets upgrade their products? How might firm size affect the benefits from accessing diverse knowledge and from participating in different learning relationships? Although access to diverse knowledge can be vital to innovation, smaller firms have a limited understanding about which new knowledge is most relevant to their context and how they may convert their capabilities into a more innovative organization. These latter aspects, we argue, come largely from relationships embedded in interfirm networks and certain types of non-market institutions that act as knowledge bridges and provide tutelage. Such institutions appear to benefit Micro firms in processing diverse knowledge. In contrast, product upgrading for SMEs improves more from their inter-firm networks, but these networks do not aid with managing diverse knowledge. We argue that differences in complementary capacities explain these variations. We use unique survey data from the Argentine wine industry.     

Providing differentiated services in CDMA wireless networks

With much more advanced techniques employed, various applications can be supported by 3G CDMA-based wireless networks. Providing differentiated service over wireless networks has become a very important issue in the design of wireless networks. A new media access control protocol with a hierarchical scheduling algorithm to provide differentiated service for CDMA-based wireless networks is proposed. This protocol evolves from the distributed queuing random access protocol for CDMA wireless network. The proposed protocol has been designed to have an ability to accommodate integrated traffic in the networks with effective scheduling schemes. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol with the hierarchical scheduling algorithm. The results reveal that the proposed solution performs effectively in the integrated traffic composed of messages with or without time constraints and achieves proportional fairness among different types of traffic.     

Underwater sensor networks: applications, advances and challenges

This paper examines the main approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize key applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers. We also provide an overview of communications hardware, testbeds and simulation tools available to the research community.     

Distributed robust optimization (DRO), part I: framework and example

Robustness of optimization models for network problems in communication networks has been an under-explored topic. Most existing algorithms for solving robust optimization problems are centralized, thus not suitable for networking problems that demand distributed solutions. This paper represents a first step towards a systematic theory for designing distributed and robust optimization models and algorithms. We first discuss several models for describing parameter uncertainty sets that can lead to decomposable problem structures and thus distributed solutions. These models include ellipsoid, polyhedron, and D-norm uncertainty sets. We then apply these models in solving a robust rate control problem in wireline networks. Three-way tradeoffs among performance, robustness, and distributiveness are illustrated both analytically and through simulations. In Part II of this two-part paper, we will present applications to wireless power control using the framework of distributed robust optimization.     

Wireless broadband drivers and their social implications

Wireless local area networks now offer high-speed Internet access at numerous locations in both public and private environments. Associated with this rapid growth, numerous social implications come to the fore, especially relating to practices, such as the free use and sharing of bandwidth. Using case-based comparative analysis, we examine three primary strategies involved in providing wireless broadband access. Based on this research, we discuss the future of Wi-Fi growth, emergent competing technologies, and the broad social implications of this phenomenon.     

分簇无线传感器网络的双时槽混合MAC协议

基于事件驱动的无线传感器网络应用,提出了一个基于分簇优化的低时延混合MAC协议--CHMAC.CHMAC采用双时槽传输调度和载波检测多路接入/时分多址接入(CSMA/TDMA)混合模式,采用适合分簇网络的时槽分配,优先保证紧急事件的最小延迟发送,并充分利用分簇网络的数据流特点,精细控制节点的侦听、睡眠以及传输功率,以提高能量有效性和网络吞吐量.理论分析和模拟试验表明,该协议能够以良好的适应性和健壮性在各种流量条件下均表现良好的性能.     

Powering Mobile Networks with Optimal Green Energy for Sustainable Development

Green wireless networking is an emerging area for many societies, especially academia and industry, in light of economic and ecological perspectives. Empowering wireless infrastructures exploiting green power sources can enhance sustainability due to the adverse effects of conventional power sources and atmospheric circumstances. Moreover, the specific power supply requirements for a base station (BS), such as cost effectiveness, efficiency, sustainability, and reliability, can be met by utilizing technological advances in renewable energy. Numerous drivers and motivators are involved in the deployment of renewable energy technologies and the transition toward green energy. Renewable energy is free, clean, and abundant in most locations throughout the year. In this work, a sustainable optimal stand-alone solar-powered model envisioning green cellular BSs for urban locations in Oman is proposed. This model can extend 24 h uninterrupted power supply support to a cellular BS that fully utilizes an integrated storage device. The system analysis is conducted using a hybrid optimization model for electric renewables (HOMER) based on actual prevailing conditions of the regions and their technical feasibility. The results showed can be achieved operational expenditure savings up to 16%. These outcomes provide a huge benefit to the cellular operators of Oman economically, technically, and ecologically.