Handoff Cost Research Articles

An Optimal Vertical Handoff Decision Algorithm for Multiple Services with Different Priorities in Heterogeneous Wireless Networks

Heterogeneous wireless networks (HWNs) have aroused numerous interest in the past few years in which efficient vertical handoff algorithms are currently attracting much attention. This paper takes into account the vertical handoff decision algorithm in HWNs where multiple types of services with different priorities are supported. By modeling the vertical handoff process as a Markov decision process, a new reward function is introduced which consists of both quality of service profit and handoff cost. Meanwhile in the proposed reward function, multiple network parameters are included for a comprehensive evaluation of the network utilization. Moreover, considering multiple services with different priorities, an online dynamic bandwidth reservation scheme is proposed based on large deviation principle. This scheme, by estimating possible bandwidth request in future time slots, reserves the bandwidth resource adaptively in advance such that the call blocking probability as well as handoff dropping probability can be guaranteed to be within an admissible range. Simulation results show that the proposed vertical handoff decision algorithm can decrease the expected handoff number by about 15---22 % and significantly increase the expected total reward compared with existing results.

Learning with handoff cost constraint for network selection in heterogeneous wireless networks

AbstractIn heterogeneous wireless networks, network selection algorithms provide the user with the optimum network access choice. The optimal network is evaluated according to network parameters. Considering that the network parameters are dynamic and unavailable for the user in realistic heterogeneous wireless network environments, most existing network selection algorithms cannot work effectively. Learning‐based algorithms can address the problem of uncertain network parameters, while they commonly need considerable network handoff, resulting in unbearable handoff cost. In order to tackle the uncertainty of network parameters, we formulate the network selection problem as a multi‐armed bandit problem. Moreover, two online learning‐based network selection algorithms with a special consideration on reducing network handoff cost are proposed. By updating in a block manner, both algorithms achieve optimal logarithmic‐order regret and limited network handoff cost. The simulation indicates that the two algorithms can significantly reduce the network handoff cost and improve the transmission performance compared with existing algorithms, simultaneously. Copyright © 2014 John Wiley & Sons, Ltd.

Performance Analysis of Multilayer MIPv6 Architecture through Experimental Testbed

Mobility management is a key issue to achieve uninterrupted Internet services in IP based network. In IPv6, the mobility management is realized by its mobile version namely the Mobile IPv6 (MIPv6). The MIPv6 is further extended to Hierarchical MIPv6 (HMIPv6) to reduce handoff latency suffered by mobile nodes and signaling load incurred due to movement if nodes within the micro mobility region defined by HMIPv6. The HMIPv6 is considered as first widely accepted layered architecture for mobility management for IPv6 network. Influenced by the benefits of HMIPv6, many researchers have suggested extension of MIPv6 into multiple layers. However, there is very little work on finding optimal levels of hierarchy in such layered architecture. The focus of this paper is to evaluate the performance of a multilayer (N-layered with N as 5) MIPv6 architecture through experimental testbed. We have observed handoff latency, signaling overhead and tunneling cost and figured out the optimal levels of hierarchy that provides the best acceptable results for all the observed parameters. Since, HMIPv6 outperforms MIPv6 in terms of handoff latency and signaling cost, so we compare our results with HMIPv6. Testbed observation depicts that three levels of hierarchy in MIPv6 architecture provides optimal performance with 27 % reduction in handoff latency and 67 % reduction in signaling overhead compared to single layer architecture like Hierarchical MIPv6 (HMIPv6) protocol.

Route Prediction Based Vehicular Mobility Management Scheme for VANET

Since improvement of wireless communication, IP based mobility management protocols have been studied to provide seamless communication and mobility management. The vehicular ad hoc network (VANET) is one of mobility management protocols, especially providing seamless connection with inter/intra/inner vehicle communication. However, each vehicle moves fast that causes short-lived connections with Access Router (AR). Based on vehicles' characteristic, it is hard to provide the availability of IP services in VANET. The most critical issue of the design of scalable routing algorithm is to provide robustness of frequent path disruption caused by vehicles' mobility. In this paper, we pursue the characteristics of vehicles' mobility and analyze them. With the navigation information which is one of vehicles' mobility characteristics, we classify the mobility into intrahighway mobility and global mobility management. Furthermore, we propose mobility management scheme based on route prediction in VANET. Handoffs with intrahighway mobility are managed locally and transparency is provided to CHs, while global mobility is managed with Mobile IPv6. Finally, through the numerical analysis, we show that proposed mobility management protocol reduces handoff latency, signaling costs, and packet loss.

LBMA: A novel Locator Based Mobility support Approach in Named Data Networking

To enhance seamless source mobility support in the mobile NDN (Named Data Networking) environment, we propose a novel Locator Based Mobility support Approach, dubbed LBMA. In this approach, we assign a unique topologically layered locator to each AR (Access Route) in NDN network, and extend the AR with additional functionalities, such as caching and forwarding Interest packets on behalf of the source. Meanwhile, we add an optional field to the original NDN packet, and modify the Outgoing Interface(s) field in the AR's original FIB (Forwarding Information Base) entries, to record the mobility status and the current locator of the source. Specifically, the consumer in LBMA can continue the interrupted communication, without delivering Interest packets towards the old location of the source, nor waiting for all relevant devices completing the FIB entries updating. The performance analysis result indicates that LBMA has lower handoff cost and shorter handoff latency, compared with other existing source mobility support approaches.

Dynamic User Demand Driven Online Network Selection

Network selection plays a key role in reaping the potential benefit of heterogeneous wireless networks. Aiming at improving the user's quality of experience, we study the network selection problem with time-varying user demand and non-uniform network handoff costs in a dynamic environment. One appealing solution in converging the time-vary user demand and the diverse network performance is dynamic network selection, which, however, poses the dilemma between satisfying user demand and controlling the network handoff cost. To get around this problem, we propose an online network selection algorithm to learn the optimal network selection policy with network handoff cost consideration. In addition, we exploit the inherent dependency in the problem and derive another two algorithms with much faster convergence speed. Simulations reveal that the proposed algorithms can achieve 10%~ performance gain over existing methods.

Handoff Delay-Based Call Admission Control in Cognitive Radio Networks

In this paper, we investigate how to achieve call admission control (CAC) for guaranteeing call dropping probability QoS which is caused by handoff timeout in cognitive radio (CR) networks. When primary user (PU) appears, spectrum handoff should be initiated to maintain secondary user (SU)'s link. We propose a novel virtual queuing (VQ) scheme to schedule spectrum handoff requests sent by multiple SUs. Unlike the conventional first-come-first-served (FCFS) scheduling, resuming transmission in the original channel has higher priority than switching to another channel. It costs less because it avoids the cost of signaling frequent spectrum switches. We characterize the handoff delay on the effect of PU's behavior and the number of SUs in CR networks. And user capacity under certain QoS requirement is derived as a guideline for CAC. The analytical results show that call dropping performance can be greatly improved by CAC when a large amount of SUs arrives fast as well as the VQ scheme is verified to reduce handoff cost compared to existing methods.

A comparative signaling cost analysis of Macro Mobility scheme in NEMO (MM-NEMO) with mobility management protocol

NEMO BSP is an upgraded addition to Mobile IPv6 (MIPv6). As MIPv6 and its enhancements (i.e. HMIPv6) possess some limitations like higher handoff latency, packet loss, NEMO BSP also faces all these shortcomings by inheritance. Network Mobility (NEMO) is involved to handle the movement of Mobile Router (MR) and it's Mobile Network Nodes (MNNs) during handoff. Hence it is essential to upgrade the performance of mobility management protocol to obtain continuous session connectivity with lower delay and packet loss in NEMO environment. The completion of handoff process in NEMO BSP usually takes longer period since MR needs to register its single primary care of address (CoA) with home network that may cause performance degradation of the applications running on Mobile Network Nodes. Moreover, when a change in point of attachment of the mobile network is accompanied by a sudden burst of signaling messages, "Signaling Storm" occurs which eventually results in temporary congestion, packet delays or even packet loss. This effect is particularly significant for wireless environment where a wireless link is not as steady as a wired link since bandwidth is relatively limited in wireless link. Hence, providing continuous Internet connection without any interruption through applying multihoming technique and route optimization mechanism in NEMO are becoming the center of attention to the current researchers. In this paper, we propose a handoff cost model to compare the signaling cost of MM-NEMO with NEMO Basic Support Protocol (NEMO BSP) and HMIPv6.The numerical results shows that the signaling cost for the MM-NEMO scheme is about 69.6 % less than the NEMO-BSP and HMIPv6.

A mobility support scheme for 6LoWPAN

This paper proposes a mobility support scheme for 6LoWPAN. In the scheme, the control information interaction for the mobile handoff is achieved in the link layer, and the routing of the control information is automatically performed through the network topology, which saves the power and the delay time consumed by the routing establishment. In addition, neither does the mobile entity need a care-of address during the mobility process, nor is involved in the mobile handoff process, which reduces the mobile entity’s power consumption and prolongs its life span. From the theoretical and simulative perspectives, the paper analyzes the performance parameters, including the mobility handoff cost, the mobility handoff delay time and packet loss rate, and the analytical results show that the performance of the scheme is better than other schemes.

A call quality performance measure for handoff algorithms

This paper proposes a new approach for performance evaluation and comparison between existing handoff algorithms taking into consideration signal levels, call dropping, and handoff cost. Using the new approach, existing handoff algorithms are then compared in terms of signal quality and number of handoffs required to achieve a desired overall signal quality. We also provide in this paper a method to estimate handoff cost and to optimize handoff sequences for retrial (where repeated call attempts are made after a call is lost) and non-retrial models based on the proposed approach. We observe that the Threshold with Hysteresis method performs better than other known methods including the one used in the GSM standard. Our results indicate that the Threshold with 4 dB Hysteresis method performs well for urban areas although with a high dropping probability, whereas the Threshold with 6 dB Hysteresis method suits for suburban areas with a low dropping probability. We find that handoff sequences obtained by existing handoff methods are less efficient than the optimal handoff sequence given in the paper by a margin of 29–45% for retrial model, and by 34–77% for non-retrial model. The paper also suggests some specific parameter values to improve the performance of currently used handoff methods based on our findings. Copyright © 2010 John Wiley & Sons, Ltd.

무선랜 시스템에서 속도에 따른 이동노드 네트워크 성능 보장을 위한 AP 선택 핸드오프 개선기법

무선 네트워크에서 핸드오프가 발생할 경우 기존의 AP탐색과정은 신호세기 정보를 이용하여 다수의 AP들 중에서 하나를 선택한다. IEEE 802.11은 매체를 공유함으로써 채널을 획득하기 위해 경합하는 CSMA/CA를 이용한 접속방식이다. 그러므로 네트워크 성능은 신호세기 외에도 네트워크에 참여하는 노드들의 수와 네트워크 혼잡에 의해 큰 영향을 받는다. 본 논문에서는 새로운 AP를 선택하는 과정에서 이동노드의 네트워크 성능을 보장하는 핸드오프를 구현하기 위해서 추가적인 AP선택 지표와 새로운 핸드오프 알고리즘을 제안했다. 이 지표는 이동노드의 네트워크 정보를 반영하는 핸드오프 비용 함수를 포함하고 있으며, 이것을 이용해 이동노드가 네트워크 정보를 이용한 네트워크 성능을 보장하는 핸드오프를 가능하게 했다. 또 이동노드를 고속 이동노드와 저속 이동노드로 나누어 핸드오프 시 고속 이동노드는 신호세기 정보로 AP를 선택하고, 저속 이동노드는 해당 영역에 있는 AP 네트워크 정보를 이용하여 AP를 선택 할 수 있도록 하였다. 그 결과 이동노드가 동시에 접속하는 무선 네트워크 환경에서도 성능 개선 효과를 얻을 수 있고, 사용자의 분산으로 자원과 망 관리의 효율적인 측면에서도 상당한 효과가 있음을 시뮬레이션을 통하여 검증하였다. When Handoff occurs at wireless network, existing AP search chooses one of various APs according to signal strength information. However, IEEE 802.11 uses Medium Access method with CSMA/CA that competes to obtain a channel by sharing medium. Therefore, network performance is heavily affected by the number of nodes and network congestion aside from signal strength. This scheme presented an additional AP selection indicator and a new handoff algorithm to realize handoff guaranteeing the network performance of mobile node in a process selecting new AP. This indicator is includes a handoff cost function reflecting the network information of mobile node, and the mobile node made handoff guaranteeing the network performance using network information possible by using this. also we classified the nodes into high-speed node and low-speed node. Then, when Handoff occurs, high-speed node was made itself choose AP by signal strength information. We also made the low-speed node choose its AP by using AP network information which is applied area. Hence, we demonstrate through simulation that gets an improvement in performance, even in the wireless network which many users concurrently access to, and it has considerable effects on aspects of resources and network management by distribution of users.

Cell-to-switch assignment in cellular networks using barebones particle swarm optimization

Cell assignment is an important issue in the area of resource management in cellular networks. The problem is an NP-hard one and requires efficient search techniques for its solution in real-time. In this letter, in order to minimize the cabling and handoff costs, we use two novel discrete particle swarm optimization (PSO) algorithms, the barebones (BB) and the exploiting barebones (BBExp) PSO variants. The impact of network and algorithm parameters on the solution accuracy and computational cost of the methods is investigated. Comparisons with optimization methods in the literature demonstrate the benefits of our proposal.

Handoff Cost Minimization and Planning of Next Generation Heterogeneous Integrated Overlay Networks

Next-generation wireless technologies have seen a paradigm shift as multiple standards and protocols emerge almost every day. Each standard has its limitations and merits, which can be either masked or complemented by other standards. For commercialization, various services should be provided in a cost effective manner, compelling a service provider to roll out integrated next generation wireless networks to exploit the virtues of each. This paper discusses the planning problem of overlay network integrating, particularly 3G, WiMAX and WLAN, establishing proper connectivity among the three networks. In the proposed planning approach, the authors focused on the initial phase and have minimized the cost for vertical handoff generated, and the cost for wire line connection amongst the various network gateways of the overlay hierarchy. To validate the planning problem, the simulated annealing (SA), a well-cited meta-heuristic H-II are presented and compared with a variant of distance based planning (DBP).

Integrated Interswitch Cable and Handoff Cost Minimizing Heuristics for Cell-to-Switch Assignment in Wireless Cellular Networks

Cell-to-switch assignment (CSA) is a well-known NP-hard problem for location management in a wireless cellular network (WCN). In this paper, we focus on the probabilistic CSA problem, where interswitch handoffs, call arrivals, and call dwell times are considered stochastic with certain distributions, and propose two heuristic approaches to solve the problem. We present an analytical framework to derive interswitch handoff frequencies among the cells. The first heuristic does not consider the load-balancing issue, whereas the second heuristic considers the load balancing among the different switches while assigning cells to them. We compare our heuristics with taboo search (TS) and find that they significantly outperform the metaheuristic TS. After minimizing the objective function comprising amortized cable and variable interswitch handoff costs, our heuristics attain a minimum that is very close to the theoretical lower bound. The merit of our heuristics lies in the fact that those can be deployed online and can provide an adaptive solution to the design problem.

Heterogeneous Wireless Networks: Configuration and Vertical Handoff Management

Vertical handoff is one of the most important issues for the next generation heterogeneous wireless networks. However, in many situations, unbeneficial vertical handoffs occur across intersystem heterogeneous networks cause network performance degradation. Therefore, we propose a novel configuration architecture that can be deployed in the next generation of wireless networks. Second, we propose a predictive and adaptive Vertical Handoff Decision Scheme that optimizes the handoff initiation time as well as selection of the most optimal network. The proposed vertical handoff decision algorithm considers the technology type as well as the Signal to Interference Ratio (SIR), the Mobile Station (MS) velocity, the user preferences, the applications requirements and the terminal capabilities as the most important factors to make vertical handoff decision. In order to minimize handoff costs, the proposed decision algorithm uses the dwell timer concept. The handoff costs are analyzed in terms of unnecessary and unbeneficial handoffs rate.The simulation results show that the reduction of unnecessary handoffs proposed in our vertical handoff decision scheme reduces the handoff blocking probability, the packets loss rate and the handoff overhead

A Proactive mobile‐initiated fast handoff scheme using the multihomed approach

AbstractMobile IP (MIP) defines a mobility management for mobile users to continuously access data when the currently attachment is changed to another network. However, when mobile node (MN) roams between network segments, the handoff latency results in packet losses and transmission delay. In this paper, we propose a multihomed fast handoff scheme (MFH‐MIP) to decrease the handoff cost. In the proposed MFH‐MIP scheme, each MN is implemeted with the link layer trigger and multihomed techniques. Based on the link layer trigger, MN can collect signal strengths of nearby access points (APs) and switch to a new link automatically when the old link becomes unsuitable to connect. Using the multihomed technique, MN can prepare for handoff using two (or more) interfaces, in which (i) one is connected with the old link to receive packets and (ii) the other one is used to access nearby APs and select the most suitable one as the new link, in parellel. In this way, MN can continuously transmit and receive packets during handoff. Based on the proposed method, MN can roam smoothly among different networks in the wireless environment. Copyright © 2008 John Wiley & Sons, Ltd.

Cell Breathing in Wireless LANs: Algorithms and Evaluation

Wireless LAN administrators often have to deal with the problem of sporadic client congestion in popular locations within the network. Existing approaches that relieve congestion by balancing the traffic load are encumbered by the modifications that are required to both access points and clients. We propose cell breathing, a well-known concept in cellular telephony, as a load balancing mechanism to handle client congestion in a wireless LAN. We develop power management algorithms for controlling the coverage of access points to handle dynamic changes in client workloads. We further incorporate hand-off costs and manufacturer specified power level constraints into our algorithms. Our approach does not require modification to clients or to the standard. It only changes the transmission power of beacon packets and does not change the transmission power of data packets to avoid the interactions with auto-rating. We analyze the worst-case bounds of the algorithms and show that they are either optimal or close to optimal. In addition, we evaluate our algorithms empirically using synthetic and real wireless LAN traces. Our results show that cell breathing significantly outperforms the commonly used fixed power scheme and performs at par with sophisticated load balancing schemes that require changes to both the client and access points

Time efficient heuristics for cell-to-switch assignment in quasi-static/dynamic location area planning of mobile cellular networks

This paper presents a set of time efficient, sub-optimal heuristics to solve the problem of assigning cells to mobile switching centers (or, switches in short) for an effective location area (LA) planning in a mobile cellular network (MCN). A common objective of this NP-hard optimization problem, termed as cell-to-switch assignment (CSA) in the literature, is to minimize the hybrid cost, comprising handoff cost between adjacent cells, and the cable cost between cells and switches, subject to the constraint that the call volume to be handled by a switch should not exceed its traffic handling capacity. To solve CSA for a quasi-static/dynamic LA design, we need fast algorithms capable of producing acceptable solutions within a reasonable time. In this work, we first propose four variants (termed as heuristics III through VI) of our earlier heuristic (termed as heuristic II) and compare all of them with other published heuristics in respect of execution time and solution cost. Results indicate that though no single heuristic performs equally well with respect to both optimality and speed, heuristic IV is the best of the lot. Secondly, we modify the original CSA problem to include the factor of load balancing amongst switches (thereby minimizing unfairness), and propose a new CSA algorithm with load balancing (CALB), which emphasizes more on load balancing than on cost optimization. It is found that CALB is fast as heuristic VI, and performs extremely well in balancing the traffic amongst the switches, thereby increasing the overall scalability of MCNs against the increase in either mobile user density or per user traffic.

On the cost and safety of handoffs in content-based routing systems

Content-based routing of information and publish/subscribe have been proposed as a communication paradigm for advanced and mobile applications. In content-based routing, messages are forwarded based on queries on their content that clients and routers establish beforehand. In this paper, we examine the cost and safety of handoff protocols for subscribers and publishers in content-based routing networks. We examine two useful properties for mobility-aware content-based routing systems, namely completeness and mobility-safety. Then we determine the upper and lower bound handoff costs for three interesting topologies, a number of optimizations, and show that if completeness cannot be assumed the signalling cost is considerably higher and flooding needs to be used. We present simulation results for subscriber mobility and mobility-safety proofs for the investigated protocols. Both theoretical and experimental results show that rendezvous points may be used to significantly reduce the signalling cost of handoffs.

Multiservice Vertical Handoff Decision Algorithms

Future wireless networks must be able to coordinate services within a diverse-network environment. One of the challenging problems for coordination is vertical handoff, which is the decision for a mobile node to handoff between different types of networks. While traditional handoff is based on received signal strength comparisons, vertical handoff must evaluate additional factors, such as monetary cost, offered services, network conditions, and user preferences. In this paper, several optimizations are proposed for the execution of vertical handoff decision algorithms, with the goal of maximizing the quality of service experienced by each user. First, the concept of policy-based handoffs is discussed. Then, a multiservice vertical handoff decision algorithm (MUSE-VDA) and cost function are introduced to judge target networks based on a variety of user- and network-valued metrics. Finally, a performance analysis demonstrates that significant gains in the ability to satisfy user requests for multiple simultaneous services and a more efficient use of resources can be achieved from the MUSE-VDA optimizations.