Network Entry Procedure Research Articles

CONNECTIVITY IN MOBILE MULTIHOP RELAY NETWORK

Mobile Multihop Relay (MMR) network is an attractive and low-cost solution for expanding service coverage and enhancing throughput of the conventional single hop network. However, mobility of Mobile Station (MS) in MMR network might lead to performance degradation in terms of Quality of Service (QoS). Selecting an appropriate Relay Station (RS) that can support data transmission for high mobility MS to enhance QoS is one of the challenges in MMR network. The main goal of the work is to develop and enhance relay selection mechanisms that can assure continuous connectivity while ensuring QoS in MMR network using NCTUns simulation tools. The approach is to develop and enhance a relay selection for MS with continuous connectivity in non-transparent relay. In this approach, the standard network entry procedure is modified to allow continuous connectivity with reduced signaling messages whenever MS joins RS that is out of Multihop Relay Base Station (MRBS) coverage and the relay selection is based on Signal to Noise Ratio (SNR). The QoS performances of the proposed relay selections are in terms of throughput and average end-to-end (ETE) delay. The findings for the proposed relay selection in non-transparent relay shows that the throughput degradation between low mobility MS (30m/s) and high mobility MS (50m/s) is only about 2.0%. The proposed relay selection mechanisms can be applied in any high mobility multi-tier cellular network.

A Preamble Design Technique for Efficient Handover in IEEE 802.16 OFDM-Based Mobile Mesh Networks

In this paper, a hierarchical design concept of a preamble for orthogonal frequency-division multiplexing (OFDM)-based mobile mesh networks (MMNs) is proposed to reduce the handover overhead by distinguishing an intercluster handover event from an intracluster handover event at the physical layer. The handover procedure using the proposed preamble can simplify the scanning procedure and skip/simplify the network entry procedure, resulting in a significant reduction of the handover overhead. The performance of the handover procedure using the proposed preamble is evaluated using the parameters in the IEEE 802.16 mesh mode.

차량 탑재형 이동 중계기의 분산 주파수 분할 기법

In this paper, we proposed that decentralized frequency allocation scheme(DFAS) without network entry procedure between relays in mobile relay system. Frequency Indicator(FI) signal which is the reference signal of frequency division of each relay and Energy Detection(ED) region are defined. In addition, the mobile connected to the relay transmits the FI signal to neighbor relays in order to facilitate communication between relays. Finally, by using this scheme, the cell throughput improvement is confirmed.

Improving Mobile WiMAX EAP-TTLS Authentication with Minimum Downtime and Securing its Management Channel

ABSTRACT Increasing the level of security with minimum downtime in a wide area WiMAX network, with thousands of fixed and mobile subscribers will encounter practical problems. We refer mainly to increase authentication, protecting the management channel, the moment of changing AAA server policy, the x.509v3 digital certificates generation, the EAP.xml configuration and the CAs recognized by the network. Doing this with minimum downtime to the active services and with a limited number of system engineers is also a challenge. The approach presented in this paper is a solution for increasing the security level of a live geographically dispersed WiMAX network, independent from the vendor. 1. Introduction Nowadays for wireless networks, security represents a priority in order to assure protected communications. In IEEE 802.16, security has been considered as the main issue during the de-sign of the protocol [1]. The Initial Network Entry procedure in an IEEE 802.16 (WiMAX) network has security defects which can be exploited by the Man-in-the-Middle (MITM) attack [2]. Improving network security in a live enterprise network with a large number of subscribers geographically dispersed should be done with minimum downtime, in order not to affect crit-ical user data/voice services. Also the management channel should be strongly protected in order to prevent intrusion in the core network that contains all of the vital servers for net-work functionality.Authentication is the validating process of a user identity and often includes validating which services a user may access and, typically involves a supplicant (that resides in the mobile station), an authenticator (that may reside in the base station or a gateway), and an authentication server [3]. EAP (Extensi-ble Authentication Protocol) is a standard protocol (frequently used in wireless networks) for data transmission authentica-tion, which is invoked by an 802.1X enabled NAS (Network Access Server) device such as an 802.11 a/b/g Wireless Ac-cess Point [4]. The EAP work group is developing algorithms of supporting many authentications like ID/Password, Certifi-cates, SMART Card and methods of session key standardiza-tion using such authentication algorithms [5]. EAP (see figure 1) integrates different authentication methods (advised by IEEE) to match the nature of the communication channel, such as EAP-PKM, EAP-MD5, EAP-OTP, EAP-GTC, EAP-TLS, EAP-SIM, EAP-AKA, and in addition a number of vendor specific methods and new proposals exist - commonly used methods capable of operating in wireless networks include EAP-TLS (Transport Layer Security), EAP-SIM (Subscriber Identity Mod-ule), EAP-AKA (Authentication and Key Agreement), PEAP (Protected Extensible Authentication Protocol), LEAP (Light-weight Extensible Authentication Protocol) and EAP-TTLS (Tun-neled Transport Layer Security) [6].

Optimization of association procedure in WiMAX networks with relay stations

When a MS enters to the WiMAX network, a network entry procedure has to be performed. The aim of procedure is twofold. Firstly, several connections between the MS and BS are created, i.e. basic, primary and secondary management connections to control data transmissions. Secondly, the MS is admitted into the network. According to the IEEE 802.16 standard, a MS always tries to associate to BS with the highest received signal quality. This method is suitable as long as the MS is directly connected to the network via BS. However by introducing relay stations to the WiMAX architecture, the MS entry procedure needs to be modified. Mainly, the point of attachment influences the network performance. This paper proposes an optimized association procedure which takes into account the use of relays stations in the network. The obtained results show improvement of system performance.

Strategies for fast scanning, ranging and handovers in WiMAX/802.16

In WiMAX/IEEE 802.16 with mobility support, the network entry procedure for a mobile station involves several steps including the scanning for an available channel and performing initial ranging in order to determine power and timing offset requirements. These steps are performed by a mobile station at start up or when about to perform a handover and must be done promptly in order to reduce delays in network access or possible dropped connections. We propose strategies that a mobile station can use to reduce the time required for scanning and ranging operations while attempting to establish network connectivity or perform a handover between neighbouring base stations. We model and simulate an area of WiMAX coverage using real-world mobility trace data and show that there are strategies that reduce the time required for scanning and ranging operations significantly.