Design and analysis of an MAC-layer protocol for acar-to-infrastructure packet radio network

The structure of a packet radio network that must operate in an environment characterized by the presence of mobile stations and a ground network with fixed access points is defined. Each of these points consists of a ground station with a certain coverage area, which must exchange data with the mobiles over a common radio channel. Mobiles within the coverage area of a ground station must coordinate their access to the common channel. The design and analysis of the multiaccess protocol is considered, together with the procedure for the passage from a ground station coverage area to the next one along the direction of flow. The overall access strategy is described and analyzed to some extent, and simulation results are provided. The integration of this medium access control (MAC) layer protocol with existing packet radio software that also covers higher layer features is also discussed     

Dynamic channel selection with reinforcement learning for cognitive WLAN over fiber

The Internet of Things (IoT) is the next big possibility and challenge for the future information networks. It makes the interaction between people and things more active and provides the connection among different existing networks. Ubiquitous short‐range wireless access and cognitive radio are key technologies for the IoT's realization. This paper deals with some problems in an integrated system of wireless local area network (WLAN) and cognitive radio — cognitive WLAN over fiber (CWLANoF). CWLANoF is a cost‐effective and efficient architecture that combines radio over fiber and cognitive radio technologies to provide centralized radio resource management and equal spectrum access in infrastructure‐based IEEE 802.11 WLANs. In this paper, a reinforcement learning approach is applied to implement dynamic channel selection in CWLANoF. The cognitive access points select the best channels among the industrial, scientific, and medical band for data packet transmission, given that the objective is to minimize external interference and acquire better network‐wide performance. The reinforcement learning method avoids solving complex optimization problems while being able to explore the states of a CWLANoF system during normal operations. Simulation results reveal that the proposed strategy is effective in avoiding aggregated interference, reducing outage probability, and improving network throughput. Copyright © 2012 John Wiley & Sons, Ltd.     

Advances in packet ratio technology

Packet radio (PR) is a technology that extends the application of packet switching which evolved for networks of point-to-point communication lines to the domain of broadcast radio. It offers a highly efficient way of using a multiple access radio channel with a potentially large number of mobile subscribers to support computer communication and to provide local distribution of information over a wide geographic area. We discuss the basic concepts of packet radio in this paper and present the recent technology and system advances in this field. Various aspects of spread spectrum transmission in the network environment are identified and our experience with a testbed network in the San Francisco Bay area is discussed.     

Management and control of transparent optical networks

Multiwavelength optical networking is expected to play a significant role in the next-generation transport networks providing capacity enhancements as well as built-in network survivability and reconfigurability. While advances have been made in the hardware technologies, considerable research effort is still required in the area of network management and control in order for optical networking to be proven commercially viable. This paper investigates key design issues concerning optical network management and control and examines how the networking architecture is influenced by the various management considerations     

Theoretical aspects in the analysis and synthesis of packet communication networks

With the intention of outlining some of the theoretical studies on the design of packet communication networks the present paper introduces the models and the basic relations underlying the analysis as well as the method for evaluating packet delay. Then the multicommodity flow problem as applied to the route assignment is described with particular reference to static and quasi-static routing schemes. Following this topological design methods are described in terms of capacity assignment, flow assignment, capacity and flow assignment, and topology, capacity and flow assignment. Theoritical studies on such factors as flow control and error control that affect the network throughput are also outlined together with the theoretical aspects on packet radio, satellite, and radio systems.     

Impact of mobility on mobile telecommunications networks

This paper describes the mobility management mechanisms for mobile telecommunications networks. There are two major types of mobility: radio network mobility and core network mobility. Radio network mobility supports radio link switching of a mobile user during conversation, and core network mobility provides roaming and tunnel‐related management for packet re‐routing due to user movement. Impact of mobility on both the radio and the core networks is addressed in this paper. Also, potential research issues on these topics are discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Techniques for Packet Voice Synchronization

Packet switching has been proposed as an effective technology for integrating voice and data in a single network. An important aspect of packet-switched voice is the reconstruction of a continuous stream of speech from the set of packets that arrive at the destination terminal, each of which may encounter a different amount of buffering delay in the packet network. The magnitude of the variation in delay may range from a few milliseconds in a local area network to hundreds of milliseconds in a long-haul packet voice and data network. This paper discusses several aspects of the packet voice synchronization problem, and techniques that can be used to address it. These techniques estimate in some way the delay encountered by each packet and use the delay estimate to determine how speech is reconstructed. The delay estimates produced by these techniques can be used in managing the flow of information in the packet network to improve overall performance. Interactions of packet voice synchronization techniques with other network design issues are also discussed.     

Real‐time and fine‐grained network monitoring using in‐band network telemetry

In the modern era of software‐defined networking (SDN), network monitoring is becoming more important for providing information about a network and helping SDN controllers to make decisions about the network. In‐band Network Telemetry (INT) is a new network monitoring framework that collects packet‐level network information to provide real‐time and fine‐grained network monitoring. In this paper, we present the design of the overall INT management architecture and its two main components: the INT management system and INTCollector. The INT management system controls heterogeneous INT‐capable devices through a common interface. INTCollector is a high‐performance collector for INT data, which uses eXpress Data Path and an event detection mechanism. The evaluation result shows that INTCollector processes telemetry reports 27 times faster than other packet‐level telemetry collectors. We made the implementation as open source, to make researchers who are interested in INT implement their own ideas on top of our work.     

Wavelet-Based Compression With ROI Coding Support for Mobile Access to DICOM Images Over Heterogeneous Radio Networks

Most of the commercial medical image viewers do not provide scalability in image compression and/or region of interest (ROI) encoding/decoding. Furthermore, these viewers do not take into consideration the special requirements and needs of a heterogeneous radio setting that is constituted by different access technologies [e.g., general packet radio services (GPRS)/ universal mobile telecommunications system (UMTS), wireless local area network (WLAN), and digital video broadcasting (DVB-H)]. This paper discusses a medical application that contains a viewer for digital imaging and communications in medicine (DICOM) images as a core module. The proposed application enables scalable wavelet-based compression, retrieval, and decompression of DICOM medical images and also supports ROI coding/decoding. Furthermore, the presented application is appropriate for use by mobile devices activating in heterogeneous radio settings. In this context, performance issues regarding the usage of the proposed application in the case of a prototype heterogeneous system setup are also discussed.      

浅议分组传送网(PTN)组网设计的要点

文章以分组传送网(PTN)在组网设计中的实际应用入手,重点分析了PTN网络在建设中需要考虑的一些主要问题.为组建适合中国移动城域网多业务承载平台,文章在PTN网络构架、保护方式、同步、网管DCN等多个方面,阐述了一些个人观点,提出了切实可行的实施方案..     

A distributed media access protocol for packet radio networks and performance analysis. Part 1: Network capacity

A distributed time-slot assignment protocol is developed for a mobile multi-hop broadcast packet radio network, using time division multiple access channel access and virtual circuit switching. The protocol eliminates the single point failure mode of centralized network management and the delays of centralized processing. It is applicable to the user-to-user communications functions of such systems as the U. S. Army's enhanced position location and reporting system (EPLRS). The important functions of the distributed protocol, including time-slot assignment, virtual circuit set-up, and network synthesis, are identified, and implementing algorithms are presented and verified. The performance analysis of the protocol is divided into two parts. In this paper, Part 1 of the performance analysis, the capacity of a network using this protocol is studied and a tool is developed to design the network capacity by trading off among the network area, the transmission range, and the number of packet radio units. Since these results are not in closed form, numerical results provide insight into these parameters. In Part 2 the network set-up time and network data rate are analysed and a hierarchical architecture for the distributed protocol is proposed and analysed.     

A design concept for reliable mobile radio networks with frequency hopping signaling

The design of a packet radio network must reflect the operational requirements and environmental constraints to which it is subject. In this paper, we outline those features that distinguish the High Frequency (HF) Intra Task Force (ITF) Network from other packet radio networks, and we present a design concept for this network that encompasses organizational structure, waveform design, and channel access. Network survivability is achieved through the use of distributed network control and frequency hopping spread-spectrum signaling. We demonstrate how the execution of the fully distributed Linked Cluster Algorithm can enable a network to reconfigure itself when it is affected by connectivity changes such as those resulting from jamming. Additional resistance against jamming is provided by frequency hopping, which leads naturally to the use of code division mutiple access (CDMA) techniques that permit the simultaneous successful transmission by several users. Distributed algorithms that exploit CDMA properties have been developed to schedule contention-free transmissions for much of the channel access in this network. Contention-based channel access protocols can also be implemented in conjunction with the Linked Cluster network structure. The design concept presented in this paper provides a high degree of survivability and flexibility, to accommodate changing environmental conditions and user demands.     

Protection of MPEG‐2 Multicast Streaming in an IP Set‐Top Box Environment

The widespread use of the Internet has led to the problem of intellectual property and copyright infringement. Digital rights management (DRM) technologies have been developed to protect digital content items. Digital content can be classified into static content (for example, text or media files) and dynamic content (for example, VOD or multicast streams). This paper deals with the protection of a multicast stream on set‐top boxes connected to an IP network. In this paper, we examine the following design and architectural issues to be considered when applying DRM functions to multicast streaming service environments: transparent streaming service and large‐scale user environments. To address the transparency issue, we introduce a ‘selective encryption scheme'. To address the second issue, a ‘key packet insertion scheme’ and ‘hierarchical key management scheme’ are introduced. Based on the above design and architecture, we developed a prototype of a multicasting DRM system. The analysis of our implementation shows that it supports transparent and scalable DRM multicasting service in a large‐scale user environment.     

CogNS: A Simulation Framework for Cognitive Radio Networks

Cognitive radio technology has been used to efficiently utilize the spectrum in wireless networks. Although many research studies have been done recently in the area of cognitive radio networks (CRNs), little effort has been made to propose a simulation framework for CRNs. In this paper, a simulation framework based on NS2 (CogNS) for cognitive radio networks is proposed. This framework can be used to investigate and evaluate the impact of lower layers, i.e., MAC and physical layer, on the transport and network layers protocols. Due to the importance of packet drop probability, end-to-end delay and throughput as QoS requirements in real-time reliable applications, these metrics are evaluated over CRNs through CogNS framework. Our simulations demonstrate that the design of new network and transport layer protocols over CRNs should be considered based on CR-related parameters such as activity model of primary users, sensing time and frequency.     

改进计算机网络可靠性的方法探析

计算机网络的可靠性设计与建设问题的解决方法是当前相关领域的研究热点问题,其对于保证计算机网络安全稳定的运行有着重要的意义。     

Enhanced VoIP Support in OFDMA-based Packet Radio Networks

As the first OFDMA-based cellular packet radio network, Evolved UTRAN has already been well studied in 3GPP and semi-persistent scheduling was selected as the most relevant packet scheduling scheme for VoIP traffic. With further evolution of Evolved UTRAN to meet the ambitious goal set by IMT-A, the performance of VoIP needs to be enhanced. In this article, we establish a semi-persistent scheduling centered framework for efficient VoIP support in OFDMA-based packet radio network and evaluate different enhancement methods, such as adaptive transmission bandwidth in persistent resource allocation, dynamic packet bundling, and frequency diversity transmission that can be added into this framework. In addition, we investigate practical constraints, e.g. wideband CQI reporting on real network performance as well as possible corrective measures. The whole system design is verified through large-scale network level simulations in which all the details of various VoIP-specific radio resource management algorithms and enhancement mechanisms as well as interactions between them are explicitly modeled. Simulation results indicate that VoIP in Evolved UTRAN can be well supported using this framework and further improved through different enhancement methods. Compared with fixed transmission bandwidth approach, adaptive transmission bandwidth approach can provide additional capacity gain of 11 and 8% respectively in 3GPP Macro Case 1 and Case 3 deployment scenario. In a highly-loaded network, switching from adaptive transmission bandwidth to dynamic packet bundling can accommodate 18 and 15% more users in Case 1 and 3 respectively. The performance degradation due to wideband CQI reporting can be partly compensated with frequency diversity transmission. It is finally concluded that the enhanced performance of VoIP is sufficient to meet the ambitious target set by IMT-A in all four ITU deployment scenarios.     

Collision resolution in packet radio networks using rotationalinvariance techniques

This paper deals with the multiuser medium access problem in the packet radio environment. Under the framework of network diversity multiple access (NDMA), a previously proposed medium access method, a blind collision resolution scheme is proposed employing rotational invariance and factor analysis techniques. The proposed approach (dubbed B-NDMA for blind NDMA) overcomes the difficulty of orthogonal identification codes required by the original protocol, thereby improving channel utilization and system capacity, while being insensitive to multipath effects and synchronization errors. Performance issues of the proposed technique are addressed both analytically and numerically     

Network issues for wireless communications

This article specifically focuses on wireless personal communications, i.e., wireless access, that provides either terminal or personal mobility. In particular, we discuss some important issues in networking, traffic, and performance. Although within radio and networking aspects there are significant commonalities between traditional cellular mobile communications and wireless personal communications, there exist distinct differences due to radio propagation and fading effects, interference environment, smaller cell sizes, type and pattern of mobility, and call delivery. Indeed, with respect to networking issues, a large set of system choices, characteristics of traffic to be carried, and important parameters have to be considered. These include the problems involved in selecting an appropriate multiaccess technology to efficiently handle the required subscriber service profile across a multiplicity of systems to complete a call. To present a meaningful discussion of these issues, we address in some detail radio resource assignment, mobility management, call control, and traffic aspect, which have significant impact on the network performance     

一种基于软件定义网络的自治服务质量管理机制(英文)

With the increase of network complexity,the flexibility of network control and management becomes a nontrivial problem.Both Software Defined Network(SDN) and Autonomic Network technologies are sophisticated technologies for the network control and management.These two technologies could be combined together to construct a software defined self-managing solution for the future network.An autonomic QoS management mechanism in Software Defined Network(AQSDN) is proposed in this paper.In AQSDN,the various QoS features can be configured autonomically in an OpenFlow switch through extending the OpenFlow and OF-Config protocols.Based on AQSDN,a novel packet context-aware QoS model(PCaQoS) is also introduced for improving the network QoS.PCaQoS takes packet context into account when packet is marked and managed into forwarding queues.The implementation of a video application's prototype which evaluates the self-configuration feature of the AQSDN and the enhancement ability of the PCaQoS is presented in order to validate this design.