Handoff Scheme Research Articles

The Predictive FHCoP-B Fast Handoff Scheme and its Performance Analysis for Nested Network Mobility

The Predictive FHCoP-B Fast Handoff Scheme and its Performance Analysis for Nested Network Mobility

A QoS Oriented Vertical Handoff Scheme for WiMAX/WLAN Overlay Networks

Recently, a number of wireless communication technologies are migrating toward heterogeneous overlay networks. The integration of Mobile WiMAX and WLAN seems to be a promising approach due to their homogeneous nature and complementary characteristics. In this paper, we investigate several important issues for the interworking of Mobile WiMAX and WLAN networks. We address a tightly coupled interworking architecture. Further, a seamless and proactive vertical handoff scheme is designed based on the architecture with aims to provide always the best quality of service (QoS) for users. Both the performance of applications and network conditions are considered in the handoff process. Moreover, we derive evaluation algorithms to estimate the conditions of both WiMAX and WLAN networks in terms of available bandwidth and packet delay. A simulation study has demonstrated that the proposed schemes can keep stations always being best connected.

Spectrum-Aware Mobility Management in Cognitive Radio Cellular Networks

Cognitive radio (CR) networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity problems. However, they face several challenges based on the fluctuating nature of the available spectrum, making it more difficult to support seamless communications, especially in CR cellular networks. In this paper, a spectrum-aware mobility management scheme is proposed for CR cellular networks. First, a novel network architecture is introduced to mitigate heterogeneous spectrum availability. Based on this architecture, a unified mobility management framework is developed to support diverse mobility events in CR networks, which consists of spectrum mobility management, user mobility management, and intercell resource allocation. The spectrum mobility management scheme determines a target cell and spectrum band for CR users adaptively dependent on time-varying spectrum opportunities, leading to increase in cell capacity. In the user mobility management scheme, a mobile user selects a proper handoff mechanism so as to minimize a switching latency at the cell boundary by considering spatially heterogeneous spectrum availability. Intercell resource allocation helps to improve the performance of both mobility management schemes by efficiently sharing spectrum resources with multiple cells. Simulation results show that the proposed method can achieve better performance than conventional handoff schemes in terms of both cell capacity as well as mobility support in communications.

A virtualization architecture for mobile WiMAX networks

Systems virtualization offers convenient means for sharing networking infrastructure while improving its utilization. This study addresses the challenges of virtualizing a commercial off-the-shelf 4G mobileWiMAX basestation. We highlight additions and modifications needed in theWiMAX network architecture for supporting multiple simultaneous virtual basestations on a single physical basestation. The most prominent features provided by the proposed virtual basestation framework include the capability to perform all frame switching at layer-2, and control mechanisms to provide isolation across slices needed to ensure experiment repeatability. By prototyping on a commercial WiMAX radio, this paper shows the usage of the virtual basestation system for housing mobile virtual network operators and testbeds alike. A use case is shown where the virtual basestation design is used to evaluate mobile handoff schemes. Another usage case is shown for optimizing a video delivery on the edge. The video delivery use case is used to show performance improvements of up to 5dB in the PSNR. Evaluation of prototype shows a significant improvement in the slice isolation, with aggregate throughput improvements of up to 192% achievable through fair resource allocation.

PERFORMANCE OF ADAPTIVE LIFE TIME BASED VERTICAL HANDOFF ALGORITHM IN HETEROGENEOUS NETWORKS

The convergence of heterogeneous wireless networks combines existing wireless networks. An effective combination of diff erent wireless networks should enable them to complement each other and pro vide high-speed data rate, wide area coverage, and quality of service (Q oS) guarantee. In Next Generation Wireless Systems (NGWS), seamless handof f between different wireless access networks plays a vital role. One of the major challenges for seamless mobility is the creation of a vertical han doff protocol. In this paper, the performance of vertical handoff is studi ed using the integration of third generation (3G) cellular and wireless loca l area networks (WLAN). The effect of application-based signal stre ngth threshold (ASST) and path loss exponent on an adaptive lifetime-base d vertical handoff (ALIVE-HO) strategy is studied in terms of number o f handoffs, aggregated throughput, and packet delay. Therefore the vertical handoff performance can be optimized in wireless and mobile networks. The present work is done for different channel conditio ns as well as different mobility schemes.

Experimental Analysis of Xie and Kuek's Traffic Model with Handoff Scheme in Wireless Networks

Mobility becomes a distinct feature for a wireless mobile cellular system. For the traffic which is non stationary and is away from the base station, the chances of a call to be handed off are increased. In urban mobile cellular systems, especially when the cell size becomes relatively small, the procedure has a significant impact on system performance. Blocking probability of originating calls and the forced termination probability of ongoing calls are the primary criteria for indicating this performance. In this paper, we report our recent work on closed form solutions to the blocking probability followed by dropping probability in wireless cellular networks with . First, we develop a performance model of a cell in a wireless network where the effect of

A novel pre-authentication scheme based on fast channel switching in IEEE 802.11 WLANs

Abstract In the case of a 3G-WLAN interworking architecture, handoff latency is mainly caused by the delays incurred when a mobile station (STA) transfers a current security context to the target access network or establishes connectivity to a new access point (AP). Existing handoff optimization schemes have mostly focused on reducing the scanning time which is to discover nearby access points. Even though the time taken by a mobile STA to authenticate the target APs contributes to the total handoff delay, the schemes to optimize the authentication time have not yet been fully investigated for providing seamless connectivity to mobile users performing handoff in WLANs. As a solution, pre-authentication, a technique performing the authentication of target APs before the completion of the handoff procedure, has attracted considerable attention to reduce the overall delay related with a handoff, which is performed within inter-subnet and/or inter-administrative domain levels. Therefore, in this article, we propose a novel pre-authentication scheme to minimize the handoff delay in 3G-WLAN interworking architecture. The proposed scheme pre-authenticates a new AP directly through a switched channel in a short period of time. Our evaluation shows that the proposed scheme outperforms the existing authentication schemes defined in the IEEE 802.11 standards in terms of authentication delay, signaling cost, and mobility rate. The proposed mechanism offers an additional advantage in that it is easy to implement and deploy by simply modifying the device driver modules of clients' WLAN interfaces.

Design and evaluation of a fast MAC layer handoff management scheme for WiFi-based multichannel Vehicular Mesh Networks

Vehicular Mesh Networks (VMNs) are important components of the wireless metropolitan networks. Compared with traditional wireless networks, they are more efficient in terms of deployment, configuration, and maintenance. However, connecting all mesh routers through wireless connection in VMNs results in the network backbone's remarkably lower bandwidth. Multichannel technology, where non-interfering channels are used to enable mesh routers to send and receive packets simultaneously, can be adopted to improve the throughput of VMNs. Due to the limited radio range of mesh routers, mobile clients have to switch among different mesh routers to maintain wireless connections. Therefore, providing smooth roaming in multichannel VMNs has become an important topic in VMN research. In this paper, a novel MAC layer handoff scheme is proposed as a means of minimizing handoff latency for WiFi-based multichannel VMNs to provide smooth communication for real-time applications. By designing a dynamic grouping algorithm for channel selection and allowing mesh routers to switch their channels for probe response messages, our scheme can shorten the waiting time for the detection of available access routers, decrease the loss ratio of data packets during the handoff, and consequently achieve smooth handoff in the MAC layer.

Distance-Based Scheme for Vertical Handoff in Heterogeneous Wireless Networks

Seamless vertical handoff between different access networks in the next generation wireless networks remains a challenging problem. A recent vertical handoff scheme that is based on Signal to Interference and Noise Ratio (SINR) may not be the best scheme for selecting the service access point or base station. Although this SINR- based scheme has higher system throughput and lower disconnection probability as compared with other vertical handoff schemes, we presume that the distance is a good criterion for decreasing service disconnection probability and increasing system throughput. The Distance-based Scheme for Vertical Handoff (DSVH) that we propose in this paper for heterogeneous wireless networks is a reactive vertical handoff scheme. We suggest that vertical handoff be based on the Received Signal Strength (RSS) and the distances to access points or base stations, where the main goal of this scheme is to enhance system performance in terms of reducing service disconnection probability and increasing system throughput. The simulation experiments show that our proposed scheme, DSVH, significantly outperforms the SINR-based scheme. It reduces the number of dropped users by 20%. However, the throughput improvrmrnt is insignificant; it is about 1%.

H.264/SVC vs. H.264/AVC video quality comparison under QoE-driven seamless handoff

This paper studies the impact of mobility management and seamless handover mechanisms on the perceived quality of video streaming applications. A seamless handoff scheme is proposed that incorporates IEEE 802.21 Media Independent Handover framework and a QoE-driven rate adaptation scheme, for both scalable and single layer coding. Quality of Experience (QoE) has been considered as an important parameter for network selection. The proposed scheme has been implemented and evaluated in a real test-bed network. Objective and subjective quality evaluation measurements for both H.264/AVC and H.264/SVC have been carried out. Through experimentation, QoE driven mobility of video streaming can be better maintained with H.264/SVC under the combined seamless handoff and rate adaptation functionality.

Secure data transmission with cloud computing in heterogeneous wireless networks

ABSTRACTIn this paper, we propose a secure handoff scheme for data transmission in integration of 3G and 802.11 wireless local area networks (WLANs). The handoff between 802.11 WLAN and the 3G suffers from some drawbacks and has been hijacked through the middle of a communication session. We propose an architecture based on cloud computing to build our scheme to fix the problems in such heterogeneous wireless networks. Adaptive Key Exchange Protocol is proposed to protect data transmission as 3G users hand over to an 802.11 WLAN. The approach includes three phases, and all steps of each phase are protected by robust public‐key encryption. Therefore, no information can be hijacked in such environment. The security analysis shows that data transmission between 802.11 WLAN and 3G is robust and secure in various aspects. Copyright © 2012 John Wiley & Sons, Ltd.

Agent assisted mobility and load aware fast handoff scheme in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a leading technology for providing various cost effective services to the end users in recent times. In this paper, we propose a new agent assisted mobility and load aware fast handoff (AMLFH) scheme in WMNs. As mesh clients (MCs) cross different boundaries, the respective agent in that domain calculates the load on mesh gateways (MGs) and guides the incoming MCs to the suitable MGs for handoff. This mechanism reduces the handoff latency. Agents exchange the gateway load index (GLI) and handoff latency values (HLV) in their respective regions before starting the handoff procedure. The performance of the proposed AMLFH scheme is evaluated by extensive simulation using various metrics. The results obtained show that the proposed scheme is quite effective than the existing schemes with respect to the metrics defined above.

A Comparative Analysis of Queuing and Fuzzy Logic based Admission Control Schemes in CDMA Cellular Network

In CDMA cellular system, the coverage area of the cell is greatly influenced by soft handoff process. The variation in soft handoff coverage area can be taken as the parameter influencing the performance parameters of the CDMA cellular system. This paper is concerned with a comparative analysis of two queuing based call admission control schemes with a fuzzy based CAC (call admission controller) model. The analytical models developed are based on channel reservation scheme for handoff calls. Finite queuing scheme for handoff call is used in first model whereas finite queuing for both handoff as well as new call is considered in the second model. The fuzzy call admission controller is implemented on Mamdani inference scheme taking relative mobility of user and number of reserved channels for handoff calls as input parameters. The output parameter is taken as handoff queue capacity. The fuzzy CAC searches for optimum handoff queue capacity to meet the QoS requirements.

Vertical handoff decision algorithm for improved quality of service in heterogeneous wireless networks

Fourth-generation networks are expected to integrate heterogeneous wireless technologies. To ensure seamless mobility across disparate wireless technologies, efficient handoff schemes are required to enhance quality of service (QoS) and offer reliable ubiquitous computing environment. This study reviews classical and existing fuzzy approaches adopted for vertical handoff to ensure seamless mobility across overlaid heterogeneous networks. A neuro-fuzzy multi-parameter-based vertical handoff decision algorithm (VHDA) is proposed. The proposed VHDA considers six parameters and applies rule-based system for vertical handoff decision. The number of vertical handoffs measured in a simulated environment shows that average number of vertical handoffs for the proposed VHDA reduces by 13.3 and 29.8% for the existing fuzzy technique and the classical technique, respectively. Further, reduction in number of unnecessary vertical handoffs in the proposed algorithm shows reduction in ping-pong effect by 15.9%, improvement in end-point service availability (ESA) and throughput by 16.57 and 5.97%, with respect to existing fuzzy technique leading towards improved QoS. Finally, the results of performance assessment, carried out using handoff quality indicator (used to quantify QoS) which is dependent upon ping-pong effect, ESA and throughput, show that the proposed VHDA offers better QoS than existing vertical handoff techniques.

Target Channel Sequence Selection Scheme for Proactive-Decision Spectrum Handoff

The problem of target channel sequence selection for proactive-decision spectrum handoff in cognitive radio networks with Poisson arriving primary users is formulated and a target channel sequence selection scheme is proposed. Theoretical analysis shows the proposed scheme can realize the minimum probability of spectrum handoff failure. Simulations show that the proposed scheme outperforms random target channel sequence selection and it performs comparable to the optimal solution in terms of the expected number of handshake trials till success.

A Novel Approach For Handoff Avoidance And Qos Improvement In Wlan

Maximizing network throughput while providing fairness is one of the key challenges in wireless LANs (WLANs). Dense deployments of WLANs suffer from increased interference and, as a result, reduced capacity and wireless network conditions in general are diverse owing to both traffic and wireless channel variations. Hence effective mechanisms are required to exploit the diversity across a multiple access points and to provide a uniform load distribution in order to improve the QoS of users and to improve the overall composite capacity. In this paper, we propose a handoff scheme considering the current active application in use rather than a single fixed threshold value and dynamically changing the threshold value depending upon the currently active applications. In addition to it, we also propose a pro-active Load Balancing scheme which completely avoids unnecessary overloading of access points by considering the load at the target access point before associating with it.

A Fast Seamless Handoff Scheme between IEEE 802.11 and EPS Networks Using Optimized Proxy Mobile IPv6

A Fast Seamless Handoff Scheme between IEEE 802.11 and EPS Networks Using Optimized Proxy Mobile IPv6

Statistical Model of Downlink Power Consumption in Cellular Cdma Networks

Present work proposes a theoretical statistical model of the downlink power consumption in cellular CDMA networks. The proposed model employs a simple but popular propagation model, which breaks down path losses into a distance dependent and a log-normal shadowing loss term. Based on the aforementioned path loss formalism, closed-form expressions for the first and the second moment of power consumption are obtained taking into account conditions placed by cell selection and handoff algorithms. Numerical results for various radio propagation environments and cell selection as well as handoff schemes are provided and discussed.

Research of an Optimized Mobile IPv6 Real-time Seamless Handover Technology

Mobile IPv6 provides mobility support for hosts connecting to the Internet, it solves addressable problems of the mobile terminal, and the mobile terminals can obtain network services without changing IP addresses. But MIPv6 can introduce substantial network expenses and lengthy handoff delay during the mobile handover process, meanwhile, more and more delay sensitive real-time applications require a packet lossless QoS guarantee during a handoff. It proposes an optimized seamless handover mechanism on the basis of existing handoff methods in this paper, it builds on top of the hierarchical method and the fast handoff mechanism and adopts a decision engine-based dynamic distributed architecture, at last it verifies that using this new handoff scheme can reduce packet loss and handoff delay efficiently and improve handoff efficiency by doing simulation experiments.

Handoff optimization in 802.11 wireless networks

In 802.11 wireless networks, a complete handoff procedure for a mobile node requires access point (AP) selection, AP switch, call admission control (CAC), IP address re-allocation, and network re-configuration. Most current handoff schemes deal only with either AP selection or IP address re-allocation. In this paper, an integrated handoff procedure is proposed. First, AP selection is accomplished by choosing an AP with the lowest channel utilization and smaller number of associated users. The information about load of each AP is reported through modified beacon frames. In the case of adopting load-based AP selection, the average throughput can be increased up to 56%, as opposed to pure SNR-based AP selection. Next, both CAC and IP address pre-fetch are performed simultaneously through the simplified DHCP procedure. Specifically, efficient limited fractional guard channel policy (ELFGCP) is proposed for the CAC phase. By adopting ELFGCP, the failure probability can be reduced as much as 45% from conventional LFGCP. Finally, the simulation results demonstrate the applicability of the integrated approach, and the overall disconnection time due to handoff can be reduced from 2.9 to 0.004 s using traditional handoff procedures.