Mobile Multi-hop Relay WiMAX Networks Research Articles

Effects of threshold based relay selection algorithms on the performance of an IEEE 802.16j mobile multi-hop relay (MMR) WiMAX network

IEEE 802.16j MMR WiMAX network introduces multi-hop relay architecture, which involves cooperative relay stations focusing on increasing the network throughput and coverage. Relay selection algorithms can be used to choose the optimal relay, which help in reducing the computational complexity during the signal processing operation of the wireless network. In this research work, a conventional Amplify-Forward (AF)/Decode-Forward (DF) assisted multi-relay IEEE 802.16j WiMAX network is considered. The effects of relay selection algorithms on the performance metrics such as Symbol Error Rate (SER) and channel capacity are investigated in detail through simulation-based study. Further, the performance of this network utilizing the proposed relay selection algorithms, namely threshold based max_min and threshold based harmonic mean of SNR, are compared with the existing max_min and harmonic mean of SNR based algorithms. Standard diversity combining techniques such as Maximal Ratio Combining (MRC) and Selection Combining (SC) are used for combining the transmitted signal at the receiver. In addition, the impact of relay locations on the performance metrics are explored. It is observed that both the proposed threshold based max_min and threshold based harmonic mean of SNR based relay selection algorithms outperform the max_min and harmonic mean of SNR based algorithms, as both the SER and channel capacity for the considered multi-relay WiMAX network is improved significantly. Further, this extensive study and analysis will be beneficial for the design of MMR WiMAX networks.

Design and Verification of Secure Mutual Authentication Protocols for Mobile Multihop Relay WiMAX Networks against Rogue Base/Relay Stations

Mobile multihop relay (MMR) WiMAX networks have attracted lots of interest in the wireless communication industry recently because of its scalable coverage, improved data rates, and relatively low cost. However, security of MMR WiMAX networks is the main challenge to be addressed. In this paper, we first identify several possible attacks on MMR WiMAX networks in which a rogue base station (BS) or relay station (RS) can get authenticated and gain control over the connections and show that the current standard does not address this problem well. We then propose a set of new authentication protocols for protecting MMR WiMAX networks from rogue BS attack, rogue RS attack, and suppress-replay attack. Our protocols can provide centralized authentication by using a trusted authentication server to support mutual authentication between RS and BS, between RS and RS, and between mobile station (MS) and RS. Moreover, our protocols can also provide distributed authentication with a license issued by the trusted server. We use a formal tool called Scyther to analyze and verify the security properties of our protocols. The results show that our protocols can counter rogue BS and RS attacks and suppress-replay attack and are not susceptible to any known attacks.

Lightweight Message Authentication Protocol for Mobile Multihop Relay Networks

This paper proposes a lightweight self-organized efficient authentication and key management scheme (SEAKS) to countermeasure the MAC layer attacks such as denial of service (DoS), replay attack, man-in-the-middle attack and the interleaving attacks in mobile multihop relay (MMR) networks. SEAKS has been developed based on privacy key management (PKM) protocol for both unilateral authentication defined as SEAKS-PKMv1 and mutual authentication as SEAKS-PKMv2. In SEAKS, the non-transparent relays (N-RS) perform authentication and establish the authorization key (AK) using our proposed public key cryptosystem based on hash authentication code scheme. The subsequent N-RS can be authenticated with less overhead thus enhancing the scalability of the system. The performance of SEAKS-PKMv1 and SEAKS-PKMv2 protocol has been evaluated using BAN LOGIC to verify the integrity of the participating N-RSs and SSs. Simulation study shows that SEAKS exhibits higher packet delivery ratio by 22%, lesser packet overhead by 12%, and less processing time by 14% as compared to the official draft scheme (OD-2009) for MMR WiMAX networks. SEAKS can be applied to any multihop networks with minimum authentication overhead.

English

Mobile Multi-hop Relay (MMR) WiMAX network uses Relay stations (RSs) to extend the cell coverage, and enhances the link quality and the throughput. In MMR WiMAX networks, the number of hops between the Subscriber stations (SSs) and the Base station (BS) is allowed to be more than two hops when Non transparent RS (NT-RS) is used. However, this requires modification to the frame structure of NT-RS to reduce the delay of relaying the data packets across multiple hops. Therefore, this paper presents a new NT-RS frame structure aimed to decrease the multi-hop relaying delay in order to improve the performance of the data transmission over MMR WiMAX network. The proposed frame structure serves the sub-ordinate SSs as well as NT-RSs in the access zones, while using the relay zones to communicate with its super-ordinate stations. The performance of the proposed frame structure is tested through a simulation work. The results showed that,the forwarding delay is reduced, and hence the link layer and the Transmission control protocol (TCP) throughput are improved significantly.   Key words: IEEE 802.16j, transmission control protocol (TCP) performance, non transparent relay stations (NT-RS), frame structure.

Secure Authentication and Key Management Protocols for Mobile Multihop WiMAX Networks

Mobile Multihop Relay (MMR) network is one of the emerging technologies, especially LTE-Advanced, WiMAX and the Smart grid communications. Ensuring security is one of the most imperative and challenging issues in MMR networks. Privacy Key Management (PKM) protocol is proposed to ensure the security measures in MMR networks. However, the protocol still faces several security threats, specifically Denial of Service (DoS), replay attacks, Man in the Middle (MitM) attacks and the interleaving attacks, which is termed as Medium Access Control (MAC) layer attacks. This paper proposed a modified version PKM protocol for both unilateral and mutual authentication, which is termed as Self-organized Efficient Authentication and Key Management Scheme (SEAKS) authentication protocol. This protocol ensures secure end-to-end data transmission using distributed hop-by-hop authentication and localized key management schemes with a very simple and efficient way. The performance evaluation of the proposed schemes in terms of packet delivery ratio, packet overhead, processing time and the effect of increasing number of rogue relay stations is carried out and compared with the official draft of MMR WiMAX and the SEN XU. The result showed that our proposed scheme out-performed the base line protocols. Keywords: Denial of Service, Hop-by-Hop Authentication, IEEE 802.16, MMR WiMAX Network, Security Issues

QoS aware transmission control scheme for multihop WiMAX network

SUMMARYThe IEEE 802.16j Mobile Multihop Relay (MMR) WiMAX network allows the number of hops between the end user and the base station to be more than two hops. It supports non‐real‐time Polling Service, which considers the minimum reserved rate and the maximum sustained rate as a QoS requirements. The reliability of sending the data over MMR WiMAX is achieved by using Transmission Control Protocol (TCP) in transport layer and automatic repeat request in the link layer. However, the use of automatic repeat request in the link layer makes the round trip time fluctuate rapidly, which increases the possibility of retransmission timeout (RTO) expiration. TCP performance degrades because of frequent timeout, and hence the QoS transmission rates cannot be satisfied. Therefore, this paper presents an RTO smoothing scheme and QoS aware transmission control to enhance the performance of data transmission over MMR WiMAX networks. The RTO smoothing scheme aims to reduce the frequent timeout occurrences. The slow start threshold and maximum congestion window are adjusted to satisfy the required QoS and it provides transmission rate fairness for the users at different hops. The results showed that, the proposed schemes reduce the timeout, and improve the utilization of the allocated resources and TCP throughput. Copyright © 2012 John Wiley & Sons, Ltd.

Dynamic relay-location-oriented group management in MMR WiMAX networks

Multihop wireless systems outperform single-hop ones in terms of coverage and capacity. The IEEE 802.16 standard, also known as Worldwide Interoperability for Microwave Access (WiMAX), is one of the latest broadband wireless access technologies over long distances. Mobile multihop relay (MMR) WiMAX networks introduce relay stations (RS) to improve range and performance at low cost. Providing multimedia capabilities to groups defined by node proximity is an interesting feature in tactical communications, which MMR WiMAX networks may support. This paper presents a dynamic group management scheme at the Medium Access Control (MAC) layer based on RS position, with dynamic RS selection, suitable for military environments where communications between close nodes are prioritary. The proposal is evaluated analytically and by simulations. Copyright © 2012 John Wiley & Sons, Ltd.

Hop Aware Scheduling Algorithm for TCP Performance Enhancement in Multi Hop Relay WiMAX

Mobile Multi-hop Relay (MMR) WiMAX networks allow the number of hops between the user and theMMR-BS to be more than two hops when the non transparent relay station is used. Transmission ControlProtocol (TCP) protocol is optimized to be used in wired networks where the main cause of loss is thecongestion. TCP throughput is highly affected by packet losses or timeout occurrences because of itscongestion control mechanism. Upon the occurrence of timeout, TCP decreases the transmission windowwhich results in throughput degradation, even if such losses are not due to congestion. This paper presentslink layer scheduling algorithm to enhance the TCP in IEEE 802.16j MMR WiMAX networks. The aim isto reduce the Retransmission Timeout (RTO) occurrences and enhance the throughput. The resultsshowed that the hop aware scheduling algorithm gives higher throughput, and less timeout occurrence fordifferent BER values.