Two-level pointer forwarding strategy for location management in PCS networks

For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.     

An efficient location forwarding with shortcut scheme for position-based routing in mobile ad-hoc networks

Position-based routing protocols are considered as having better scalability and lower control overhead than topology-based routing protocols in mobile ad-hoc networks (MANETs). Since location services are the most critical part of position-based routing protocols, we present an Efficient Location Forwarding with Shortcuts (ELFS) scheme to improve the performance of location services. The ELFS scheme uses multiple virtual home regions to achieve efficient location discovery. We develop three approaches to reducing the overhead of maintaining multiple virtual home regions. The first approach, shortcut updates, uses the idea of shortcut to decrease the frequency of global updates. The second approach, adaptive broadcasting, alleviates the cost of each global update. In certain conditions, ELFS only broadcasts the messages of location update to the regions with the longest query paths. The third approach, packet forwarding with direction awareness, reduces the path lengths of messages. It can improve the cost of transmitting location information for delay-tolerant applications. With these approaches, the frequency of global broadcasting is decreased, and the overhead of location maintenance is reduced significantly. The simulation results show that the performance of ELFS is comparably fast and stable.     

A cost effective distributed location management strategy for wireless networks

The mobility feature of mobile stations (MSs) imposes a large burden on network traffic control as a result of location management. Design issues of location management include MS registration (updating) and call setup (paging). Previous approaches introduced several network topologies for updating and paging procedures, but most of them focused on a single problem: either updating optimization or paging optimization. In this paper, we design and integrate two mechanisms, distributed temporary location caches (TLCs) and distributed home location registers (HLRs), to reduce database access delay and to decrease network signaling traffic in both updating and paging for low power, low tier micro cellular systems. By using TLCs, our approach can improve the performance of updating and paging in comparison with previous approaches. Experimental results based on our analytic model show that our location management procedures have lower HLR access rate, lower registration cost, and lower call setup cost than other approaches.     

A distributed location management strategy for next- generation IP-based wireless networks

1 Introduction Mobility management is a key technical aspect in mobile communication systems. The main purpose of mobility management is to enable mobile terminals or users to communicate with each other continuously while moving—— while minimizing data…     

Hierarchical location service for wireless sensor networks with mobile sinks

In wireless sensor networks (WSNs), a mobile sink can help eliminate the hotspot effect in the vicinity of the sink, which can balance the traffic load in the network and thus improve the network performance. Location‐based routing is an effective routing paradigm for supporting sink mobility in WSNs with mobile sinks (mWSNs). To support efficient location‐based routing, scalable location service must be provided to advertise the location information of mobile sinks in an mWSN. In this paper, we propose a new hierarchical location service for supporting location‐based routing in mWSNs. The proposed location service divides an mWSN into a grid structure and exploits the characteristics of static sensors and mobile sinks in selecting location servers. It can build, maintain, and update the grid‐spaced network structure via a simple hashing function. To reduce the location update cost, a hierarchy structure is built by choosing a subset of location servers in the network to store the location information of mobile sinks. The simulation results show that the proposed location service can significantly reduce the communication overhead caused by sink mobility while maintaining high routing performance, and scales well in terms of network size and sink number. Copyright © 2009 John Wiley & Sons, Ltd.     

Energy efficient dispatch strategy for the dual-functional mobile sink in wireless rechargeable sensor networks

Scavenging energy from radio-frequency (RF) signals has drawn significant attention in recent years. By introducing the technology of RF energy harvesting into wireless sensor networks, a new type of network named mobile data gathering based wireless rechargeable sensor network (MGWRSN) is considered in this paper. In the MGWRSN, a dual-functional mobile sink (MS) which has the abilities of data collecting and RF energy generating is employed. Data sensed by sensor nodes is gathered at several selected head nodes (HNs). Through using the RF energy supplied by the MS, the HNs deliver the gathered data to the MS arriving at the corresponding rendezvous points (RPs). In our works, the network energy consumption model of the MGWRSN is built, and the energy efficient dispatch strategy for the MS is studied, aiming at cutting down the total network energy consumption. For the simplest case, i.e., the one-HN MGWRSN, the optimal location of the RP is provided to minimize the total network energy consumption. After that, the researches are extended into the case of multi-HN MGWRSN and a heuristic dispatch strategy named HEEDS is proposed. Theoretical analysis and numerical results show that: (1) in the one-HN MGWRSN, the optimal location of the RP is close related to the data bulk to be transmitted, the unit mobility energy cost, the required bit error rate, the modulation scheme, and the departure position of the MS; (2) comparing with the existing algorithm WRP which directly dispatches the MS to the locations of HNs to collect data, the proposed strategy HEEDS is shown to be more energy efficient. Moreover, when a high energy transfer power is available at the MS, HEEDS renders shorter packet delay compared to WRP.     

Energy efficient geographical key management scheme for authentication in mobile wireless sensor networks

In wireless sensor networks, a sensor node communicates with a small set of neighbour sensor nodes and with the base station through a group leader or a cluster head. However, in some occasions, a sensor node required to move in the sensor networks. The node has to change its own position with the requirement of applications. Considering this phenomena, in this paper, we propose to design an angular function and private key management system authenticated by group leader for the transmission of a node. In the proposed scheme, the group is divided into sectors. The motion of the node is related with the angles to the group leader, which is the basis of our proposal. The nodes movement and activity should be tracked. The proposed scheme attains high connectivity and security with the help of the directional transreceiver. The lifetime of a node is increased, and it enables a node to move through the network and to transmit data to its neighbors.     

移动网络前向指针策略的鉴权管理研究

鉴权管理是移动通信移动管理中非常重要的技术,其策略的选择将直接影响网络中各网元的信令负荷。本文主要讨论移动通信系统前向指针位置管理策略中的鉴权管理。当用户在远离其HLR的不同VLR对应覆盖区域移动时,系统通过向其原VLR索取剩余鉴权数据或向其HLR申请新鉴权数据来实现用户的鉴权管理。通过鉴权开销及被呼处理时延等指标的分析,本文提出的鉴权管理算法较适合于CMR较小的MS鉴权管理;当MS的CMR增大时,本文提出的鉴权管理算法与二层管理策略如GSM或IS-41移动系统的开销及时延等指标逐渐接近。     

Dynamic mobile user location update for wireless PCS networks

The basic architecture of a personal communication network consists of a wireline network and mobile terminals. Each mobile terminal communicates with the wireline network through a nearby base station. In order to route incoming calls to a destination mobile terminal, the network must keep track of the location of each mobile terminal from time to time. This is achieved bylocation update such that each mobile terminal reports its current location to the network at specific time points. When an incoming call arrives, the network will page the mobile terminal starting from the last updated location. A trade-off, therefore, exists between the frequency of location update and the number of locations paged in order to track down the mobile terminal. This paper introduces a location update policy which minimizes the cost of mobile terminal location tracking. A mobile terminal dynamically determines when to update after moving to a new cell based on its mobility pattern and the incoming call arrival probability. The performance of this scheme is close to that of the optimal policy reported earlier. However, the processing time requirement of this scheme is very low. The minimal computation required by this scheme enables its usage in mobile terminals which has limited energy supply and computational power.     

社会属性感知的间断连接无线网络数据转发策略

间断连接无线网络中的节点具有极强的聚集特性,数据转发过程需要充分地考虑节点之间的社会关系。提出一种社会属性感知的数据分发策略,根据实时获取的多维网络状态参数,节点以分布式的方式估计其自身及其他节点的社会属性。进而确定数据携带节点与目的节点之间的关系,以最小化资源开销的方式实现数据转发。结果表明,与典型机制相比,所提出的数据转发策略具有较高的投递率和较低的延迟,有效地改善了网络性能。     

Dynamical mobile terminal location registration in wireless PCS networks

In this paper, we propose a mobile terminal (MT) location registration/update model. In this model, the registration decision is based on two factors-the time elapsed since last call arrival and the distance the MT has traveled since last registration. It is established that the optimal registration strategy can be represented by a curve. Only when the state of the system reaches this curve is a registration performed. In order for an MT to calculate its traveled distance, an interactive implementation scheme and a distance calculation algorithm are developed. When the call interarrival times are independent and geometrically distributed, the proposed model becomes a distance-based model and, in this case, the optimal registration strategy is of threshold structure. For the distance-based model, a single sample path-based ordinal optimization algorithm is devised. In this algorithm, without any knowledge about the system parameters, the MT observes the system state transitions, estimates the ordinal of a set of strategies, and updates the registration strategy adaptively. Since only a single sample path is used, this algorithm can be implemented online. Several numerical examples are provided to compare the proposed model and the existing ones.     

An efficient cooperative hybrid routing protocol for hybrid wireless mesh networks

Hybrid wireless mesh networks are the most generic types of wireless mesh networks. Unlike static mesh routers, which have multiple radio interfaces and almost no energy constraint, mobile mesh clients are usually equipped with a single radio interface and have energy limitations. A cooperative hybrid routing protocol (CHRP) combining advantages of proactive and reactive routing protocols by letting them work cooperatively is proposed in this paper, which can adapt to features of both routers and clients. In CHRP, in order to make a proper route selection, channel condition, interference and constrained energy of clients are considered in the node-aware routing metric. Besides, a cross-layer approach is used in CHRP. Both gateway and client oriented data flows are considered comprehensively. The simulation results using ns-3 show the advantage of the proposed CHRP in terms of average packet loss rate, average latency, average network throughput, average energy consumption of clients and the minimum residual energy of clients.     

On providing location privacy for mobile sinks in wireless sensor networks

A common practice in sensor networks is to collect sensing data and report them to the sinks or to some pre-defined data rendezvous points via multi-hop communications. Attackers may locate the sink easily by reading the destination field in the packet header or predicting the arrival of the sink at the rendezvous points, which opens up vulnerabilities to location privacy of the sinks. In this paper, we propose a random data collection scheme to protect the location privacy of mobile sinks in wireless sensor networks. Data are forwarded along random paths and stored at the intermediate nodes probabilistically in the network. The sinks will move around randomly to collect data from the local nodes occasionally, which prevents the attackers from predicting their locations and movements. We analyze different kind of attacks threatening the location privacy of the sinks in sensor networks. We also evaluate the delivery rate, data collection delay and protection strength of our scheme by both analysis and simulations. Both analytical and simulation results show that our scheme can protect location privacy of mobile sinks effectively, while providing satisfactory data collection services.     

An efficient distributed routing protocol for wireless sensor networks with mobile sinks

Introducing mobile sinks into a wireless sensor network can effectively improve the network performance. However, sink mobility can bring excessive protocol overhead for route maintenance and may offset the benefit from using mobile sinks. In this paper, we propose a dynamic layered routing protocol to address this problem. The proposed protocol integrates dynamic layered Voronoi scoping and dynamic anchor selection to effectively reduce the dissemination scopes and frequencies of routing updates as the sinks move in the network. Simulation results show that the proposed protocol can effectively reduce the protocol overhead while ensuring high packet delivery ratio as compared with existing work. Copyright © 2014 John Wiley & Sons, Ltd.     

Adaptive methods for location management in mobile cellular networks

Future mobile cellular networks will include complex algorithms and procedures that make them able to react optimally to the fluctuating conditions (propagation, traffic, services, ...). Among these mechanisms, location management is an important one as it deals with an essential function of the mobile cellular networks: locate each subscriber to provide him/her with the subscribed services. In this paper, we present the location management methods that are currently implemented in cellular networks and the adaptive methods that have been proposed for future mobile cellular networks. These methods are evaluated for different scenarios and their performance are compared by means of simulations.     

无线传感器网络混合定位技术研究

在大规模复杂无线传感器网络中往往采用多种节点定位技术,在此结合现有无线传感器定位技术的现状,提出了一种混合定位技术以实现不同定位方法之间的互补。一方面利用RSSI定位弥补TDOA定位覆盖范围小的缺点;另一方面将测距信息引入到非测距定位DV—Hop算法中,用RSSI测距模型来提高DV-Hop算法中定位节点与信标节点间有效距离的精度。实验结果表明,该混合定位技术实现了TDOA,RSSI以及DV-HOP等定位技术的融合,有效地提高了复杂大规模无线传感器网络的节点定位精度。     

An efficient handoff management scheme for mobile wireless ATMnetworks

A new handoff management scheme for wireless ATM networks is proposed. In this scheme, all cells are connected to their neighboring cells by permanent virtual circuits (PVCs) and to the access switch (AS) by switched virtual circuits (SVCs) which are only for new calls. Some carefully chosen cells, called rerouting cells, are also connected to the AS by PVCs. In summary, if a mobile roams to an ordinary neighboring cell, its traffic path is simply elongated by a PVC connecting the old and new cells. If a mobile roams to a rerouting cell, its traffic path is rerouted to a PVC between the AS and rerouting cell. By using PVC's for handoff calls, we can guarantee fast and seamless handoff. At the same time, our scheme improves the path efficiency by limiting the maximum number of hops that a path can be extended. Also, allowing path rerouting at a suitable time means the network resources are more efficiently utilized     

Virtual grid-based rendezvous point and sojourn location selection for energy and delay efficient data acquisition in wireless sensor networks with mobile sink

Wireless Networks - Rendezvous points (RPs) based data acquisition methods are widely accepted as the solution for data acquisition delay/latency problem. In these methods, RPs are a subset of...     

HEEC: a hybrid unequal energy efficient clustering for wireless sensor networks

Wireless Networks - An important challenge in wireless sensor networks is energy conservation. Recently, several hybrid, dynamic and static clustering protocols have been proposed to solve this...     

Modeling and efficient handling of handoffs in integrated wireless mobile networks

We propose and analyze two handoff schemes without and with preemptive priority procedures for integrated wireless mobile networks. We categorize the service calls into four different types, namely, originating voice calls, originating data calls, voice handoff request calls, and data handoff request calls and we assume two separate queues for two handoff services. A number of channels in each cell are reserved exclusively for handoff request calls. Out of these channels, few are reserved exclusively for voice handoff request calls. The remaining channels are shared by both originating and handoff request calls. In the preemptive priority scheme, higher priority is given to voice handoff request calls over data handoff request calls and can preempt data service to the queue if, upon arrival, a voice handoff request finds no free channels. We model the system by a three-dimensional Markov chain and compute the system performance in terms of blocking probability of originating calls, forced termination probability of voice handoff request calls, and average transmission delay of data calls. It is observed that forced termination probability of voice handoff request calls can be decreased by increasing the number of reserved channels. On the other hand, as a data handoff request can be transferred from a queue of one base station to another, there is no packet loss of data handoff except for a negligibly small blocking probability.