GUEST EDITORIAL - WIRELESS BROADBAND ACCESS: WIMAX AND BEYOND

The three articles selected for this special section focus on wireless broadband access, specifically WiMAX and wireless metropolitan area networks.     

WIRELESS BROADBAND ACCESS: WIMAX AND BEYOND - Investigation of Bandwidth Request Mechanisms under Point-to-Multipoint Mode of WiMAX Networks

The WiMAX standard specifies a metropolitan area broadband wireless access air interface. In order to support QoS for multimedia applications, various bandwidth request and scheduling mechanisms are suggested in WiMAX, in which a subscriber station can send request messages to a base station, and the base station can grant or reject the request according to the available radio resources. This article first compares two fundamental bandwidth request mechanisms specified in the standard, random access vs. polling under the point-to-multipoint mode, a mandatory transmission mode. Our results demonstrate that random access outperforms polling when the request rate is low. However, its performance degrades significantly when the channel is congested. Adaptive switching between random access and polling according to load can improve system performance. We also investigate the impact of channel noise on the random access request mechanism     

WiMAX网络控制架构的研究

文中提出了几种安全的面向服务的Wimax的网络控制架构。为了设计这样的架构,笔者侧重考虑通信安全和满足Wimax潜在的业务需求这两个方面因素。提出的构架里包含两个基本元素：有服务意识,统一的路由配置。另外研究了Wimax建设的关键性技术。通过理论研究,可以为建立更安全更实际可靠的Wimax网络提供一些实际可行的指导意见。     

A Cross-Layer Cognitive Radio-Based Framework and CAC Scheme in WiMAX Networks

Quality of service (QoS) provisioning is an important issue in the deployment of broadband wireless access networks with real-time and non-real-time traffic integration. The Connection Admission Control (CAC) operation is essential to guarantee the QoS requirements of connections while achieving system efficiency. Cognitive Radio is seen as a solution to the current low usage of the radio spectrum and the problem of the fixed spectrum allocation. In this paper, we propose a novel cross-layer Cognitive Radio-based QoS support framework and Cognitive Radio-based CAC scheme in WiMAX point-to-multipoint systems. By using a cross-layer approach, the proposed solution can intelligently explore unused spectrums and spread to non-active spectrums to improve the capacity of the system significantly and provide QoS guaranteed service to real-time traffic. A queueing analytical modeling for the WiAMX system has been carried out. The key system performance parameters are obtained based on the queueing analytical model theoretically. Extensive simulation experiments have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can expand the capacity of WiMAX systems up to two times while providing QoS guaranteed service to real-time and non-real-time traffics.     

Secure Service and Network Framework for Mobile Ethernet

Secure cellular data services have become more popular in the Japanese market. These services are based on 2G/3G cellular networks and are expected to move into the next-generation wireless networks, called Beyond 3G. In the Beyond 3G, wireless communication available at a user's location is selected based on the type of the service. The user downloads an application from one wireless network and executes it on another. Beyond 3G expects core and wireless operators and allows to plug-in new wireless access. A security model that can accommodate these requirements needs to be sufficiently flexible for end users to utilize with ease. In this paper, we explain the Mobile Ethernet architecture for all IP networks in terms of the Beyond 3G. We discuss usage scenario/operator models and identify entities for the security model. We separate a mobile device into a personal identity card (PIC) containing cryptographic information and a wireless communications device that offers security and flexibility. We propose a self-delegation protocol for device authentication and use a delegated credential for unified network- and service-level authentication. We also propose proactive handover authentication using the security context between different types of wireless access, such as Third Generation Partnership Project (3GPP) and WLAN, so that the secure end-to-end communication channels established by service software on the TCP/IP are not terminated. Lastly, we raise security issues regarding the next-generation platform.     

Fast and Secure Handover Authentication Scheme Based on Ticket for WiMAX and WiFi Heterogeneous Networks

Integrated WiMAX and WiFi networks is of great potential for the future due to the wider coverage of WiMAX and the high data transport capacity of WiFi. However, seamless and secure handover (HO) is one of the most challenging issues in the WiMAX and WiFi heterogeneous networks. In this paper, we present a fast and secure HO authentication scheme based on credential ticket for WiMAX and WiFi heterogeneous networks. In the proposed scheme, Mobile Station (MS) shows its corresponding credential ticket generated by the previously visited Base Station (BS)/Access Point (AP) to the target BS/AP whenever an HO occurs, and then the MS and target BS/AP can complete the mutual authentication and derive their shared session key without interacting with the Authentication, Authorization, and Accounting server, which significantly reduces the HO authentication delay. Moreover, our scheme fulfills the essential security requirements in HO authentication semantics and the formal verification by the AVISPA tool shows that the proposed scheme is secure against various malicious attacks. In addition, the theoretical analysis and simulation indicate that our scheme outperforms the existing HO authentication schemes in terms of communication and computation cost.     

A Cross-Layer Framework for Association Control in Wireless Mesh Networks

The user association mechanism specified by the IEEE 802.11 standard does not consider the channel conditions and the AP load in the association process. Employing the mechanism in its plain form in wireless mesh networks we may only achieve low throughput and low user transmission rates. In this paper we design a new association framework in order to provide optimal association and network performance. In this framework we propose a new channel-quality based user association mechanism inspired by the operation of the infrastructure-based WLANs. Besides, we enforce our framework by proposing an airtime-metric based association mechanism that is aware of the uplink and downlink channel conditions as well as the communication load. We then extend the functionality of this mechanism in a cross-layer manner taking into account information from the routing layer, in order to fit it in the operation of wireless mesh networks. Lastly, we design a hybrid association scheme that can be efficiently applied in real deployments to improve the network performance. We evaluate the performance of our system through simulations and we show that wireless mesh networks that use the proposed association mechanisms are more capable in meeting the needs of QoS-sensitive applications.     

Secure Authentication Schemes for Vehicular Adhoc Networks: A Survey

Vehicular Adhoc Network (VANET) is based on the principles of Mobile Adhoc NETwork (MANET) where vehicles are considered as nodes and secure communication is established to provide a safe driving experience. Due to its unique characteristics, it has various issues and challenges. These issues can be resolved by ensuring security requirements like authentication, privacy preservation, message integrity, non-repudiation, linkability, availability etc. Authentication plays a vital role since it is the first step to establish secure communication in the vehicular network. It also distinguishes malicious vehicles from legitimate vehicles. Different authentication schemes have been proposed to establish secure vehicular communications. A survey of the existing authentication schemes is given in this paper. At first, the existing authentication schemes are broadly classified based on message signing and verification methods. Then, each category is clearly explained with its sub-categories. At last, the existing schemes in each category are compared based on security requirements, security attacks and performance parameters.

     

一种安全的无线传感器网络路由协议

Wireless sensor networks are increasingly deployed in security-critical areas, such as battle field. However, general sensor nodes are manufactured with inexpensive components, and they are short of security enhancement. Therefore, an adversary could capture and compromise sensor nodes easily, then launch some malicious attacks （including tampering or discarding useful data collected from source nodes）. In this paper, we propose a secure routing and aggregation protocol for sensor networks, which utilizes one-way hash chain and multi-path mechanism to achieve security of wireless sensor networks.     

A Service-Oriented Medical Framework for Fast and Adaptive Information Delivery in Mobile Environment

The need for fast treatment of patients in critical conditions motivates the use of mobile devices to provide prompt and consistent communication between hospitals and physicians. We propose a framework that supports ubiquitous access to medical systems using personalized mobile services and integrated medical systems. The proposed service-oriented medical framework provides dynamically composed services that are adapted to contextual variables such as the user’s role, the network bandwidth, and resources available at mobile devices while supporting task allocation in distributed servers for massive resource-consuming services. It also manages accurate patient data by integrating local medical systems using medical information standards such as Digital Imaging and Communications in Medicine and Health Level 7. We have demonstrated the effectiveness of our framework by building a prototype of context-based adaptation of computerized tomography image retrieval for acute stroke treatments, which allows images to be viewed on mobile devices with WiMax wireless network. The proposed medical framework reduces hospital delays of patients and facilitates treatments in the absence of medical specialists.      

A Cross-Layer Admission Control Framework for Wireless Ad-Hoc Networks using Multiple Antennas

Unlike single omnidirectional antennas, multiple antennas offer wireless ad-hoc networks potential increases in their achievable throughput and capacity. Due to recent advances in antenna technology, it is now affordable to build wireless devices with more than one antenna. As a result, multiple antennas are expected to be an essential part of next-generation wireless networks to support the rapidly emerging multimedia applications characterized by their high and diverse QoS needs. This paper develops an admission control framework that exploits the benefits of multiple antennas to better support applications with QoS requirements in wireless ad-hoc networks. The developed theory provides wireless ad-hoc networks with flow-level admission control capabilities while accounting for cross-layer effects between the PHY and the MAC layers. Based on the developed theory, we propose a mechanism that multiple antenna equipped nodes can use to control flows' admissibility into the network. Through simulation studies, we show that the proposed mechanism results in high flow acceptance rates and high network throughput utilization.     

GSHMAC: Green and Secure Hybrid Medium Access Control for Wireless Sensor Network

The cost efficiency of wireless platforms and their easy deployment enable the applicability of it in widespread application domains. Wireless sensor networks (WSNs) are not excluded from it. Their application domains vary from industrial monitoring to military applications. A WSN is a resource-constrained network and energy of the WSN node is a valuable resource. Like every other network, WSNs are also vulnerable to security attacks. A security attack can results in networks consuming more resources, leading to earlier depletion of node energy. A significant part of the resource consumption in a WSN is controlled by the medium access control (MAC) mechanism. This paper focuses on WSN MAC mechanisms and countermeasures for attacks targeting the MAC layer in a WSN. Denial of sleep attacks are the most relevant for WSN MAC as these types of attacks have shattered effects, which bring down the sensor lifetime from years to days. This paper proposes a secure hybrid MAC mechanism, Green and Secure Hybrid Medium Access Control (GSHMAC) to overcome the devastating effect of WSN MAC attacks. The proposed mechanism provides features such as collision threshold-based MAC mode control and countermeasures on WSN MAC using internal MAC mechanisms. GSHMAC shows improved energy-efficiency, delay, and throughput in the presence of attacks, as compared with state-of-art secure MAC mechanisms.     

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.     

Ariadne: A Secure On-Demand Routing Protocol for Ad Hoc Networks

An ad hoc network is a group of wireless mobile computers (or nodes), in which individual nodes cooperate by forwarding packets for each other to allow nodes to communicate beyond direct wireless transmission range. Prior research in ad hoc networking has generally studied the routing problem in a non-adversarial setting, assuming a trusted environment. In this paper, we present attacks against routing in ad hoc networks, and we present the design and performance evaluation of a new secure on-demand ad hoc network routing protocol, called Ariadne. Ariadne prevents attackers or compromised nodes from tampering with uncompromised routes consisting of uncompromised nodes, and also prevents many types of Denial-of-Service attacks. In addition, Ariadne is efficient, using only highly efficient symmetric cryptographic primitives.     

A Secure Stop and Wait Communication Protocol for Disturbed Networks

Wireless Personal Communications - Secure data communication is the need of hour today specifically when the wireless communication channel is insecure. We are proposing a protocol which can be...     

WiMAX与WLAN跨层优化切换的研究

通过结合IETF提议的快速移动IPv6（FMIPv6）协议与IEEE802.21工作组提出MIH（Media Independent Handover）草案,引入了一种WiMAX与WLAN垂直切换的跨层优化方案。此外,移动节点引入信息映射表,在存储链路质量下降之前以MIH消息检索介质独立信息服务器MIIS获取邻居网络信息,减少了IP层切换初始化获取邻居网络信息的时间,增强了FMIPv6预测切换成功概率,减少了切换时延和丢包率。     

针对移动视频流介于UMTS和WiMAX网络间的切换方案

下一代移动网络(NGMN)倾向于融合多个无线接入技术(RATs)来为用户提供无处不在的访问服务。而作为一个无处不在系统,能够有一个解决方案来支持日益流行的视频应用程序也是至关重要的。由于移动视频应用程序的高带宽要求和对延迟敏感的特点,如何让移动视频应用程序在不同的RATs之间进行无缝切换并保证服务质量(QoS)是我们面临的一个挑战。为了加快实现在异构网络中提供无缝视频流服务,通过运用IEEE 802.21规定的媒体独立信息服务的服务器提出了一种移动端发起-网络端控制的移动网络切换方案。仿真结果表明,该方案在丢包率、延迟和峰值信噪比等方面提高了性能。     

Information-Defined Networks:A Communication Network Approach for Network Studies

The research of complex networks facili-tates the progress of various disciplines,including bi-ology,chemistry,social science,computer,and com-munication engine...     

SECRECSY: A Secure Framework for Enhanced Privacy-Preserving Location Recommendations in Cloud Environment

Wireless Personal Communications - The development of Recommender Systems (RSs) aims to generate recommendations with high quality, and on the other hand, the privacy of the user is not considered...