Low-cost binding update scheme based on pointer forwarding in HMIPv6 network

By introducing a mobility anchor point(MAP),hierarchical mobile IPv6(HMIPv6)reduces the binding update signaling cost associated with mobile IPv6,but there still exist deficiencies.For instance,a mobile node(MN)needs to orderly accomplish two binding updates with the MAP and home agent(HA)when the MN performs inter-MAP mobility.This results in a high signaling cost,thus affecting network performance.To reduce the inter-MAP binding update cost of idle MN in HMIPv6,an optimization scheme based on pointer forwarding with a threshold is proposed.The scheme can reduces the binding update cost of idle MN by using the binding update between MAP to replace several home binding updates.The signaling cost difference is derived by analyzing the cost of the basic scheme and the optimization scheme between two successive sessions.Simulation results show that,the optimization scheme can reduce the binding update signaling cost and improve the network performance as long as a suitable threshold is chosen.The discussions on the sensitivity of tele-parameters are also given.     

A FAST SEAMLESS HANDOVER SCHEME AND ITS CDT OPTIMIZATION FOR PING-PONG TYPE OF MOVEMENT

In mobile IPv6 networks, the ping-pong type of movement brings about frequent handovers and thus increases signaling burden. This letter proposes a fast seamless handover scheme where the access router keeps the mobile node＇s old reservation till the offline Count Down Timer （CDT） expires in order to reduce handover signaling and delay while the mobile node returns in a very short period of time. Based upon a poisson mobility model, an simple expression for CDT optimization is given out for the scheme to achieve the best cost performance of resource reservation.     

An Enhanced Location‐Based Location Update Scheme in Mobile Cellular Networks

In this study, we consider a location‐based location update (LU) scheme. We propose an enhanced LU (ELU) scheme that can store more cells to reduce the location update cost of the LU scheme and show that the ELU scheme always outperforms the LU scheme. Our scheme can be easily implemented in actual cellular systems.     

基于TOA指纹数据库的小小区发现

在小小区大量部署的网络场景下,用户进行异频扫描所检测的载波数相比传统网络部署场景会大量增加,因此用户能耗也会相应增加.基于此,提出了一种基于宏小区参考信号到达时间(TOA)指纹数据库的小小区发现策略,通过减少用户不必要的异频检测操作,进而减少用户能量消耗,以解决用户在进行小小区发现时可能存在的能耗过高问题.仿真表明,该方案相比现有的基于参考信号接收功率(RSSI)指纹数据库方案,受噪声影响程度低,小小区发现准确率高.同时,该方案能有效地限制处于高速移动状态的用户进行异频检测,从而增大了用户与小小区连接的成功率.     

Modeling frame synchronization for UMTS high-speed downlink packet access

Third Generation Partnership Project (3GPP) specification TR 25.950 proposed high-speed downlink packet access for the Universal Mobile Telecommunication System (UMTS). In this mechanism, an active set of cells is defined for every user equipment (UE) communication session. The cell with the best wireless link quality (called the serving cell) in the active set is selected for communication with the UE. When the wireless link quality of the old serving cell degrades below some threshold, a new serving cell in the active set is selected to continue the communication session. Our previous work proposed a high-speed downlink packet access (HSDPA) overflow control scheme with four frame synchronization algorithms to switch the serving cell, and formally proved the correctness of the scheme. We propose an analytic model to investigate the performance of these frame synchronization algorithms, and show how the user movement patterns affect the control message delivery costs of these algorithms.     

Movement-based location update and selective paging for PCSnetworks

This paper introduces a mobility tracking mechanism that combines a movement-based location update policy with a selective paging scheme. Movement-based location update is selected for its simplicity. It does not require each mobile terminal to store information about the arrangement and the distance relationship of all cells. In fact, each mobile terminal only keeps a counter of the number of cells visited. A location update is performed when this counter exceeds a predefined threshold value. This scheme allows the dynamic selection of the movement threshold on a per-user basis. This is desirable as different users may have very different mobility patterns. Selective paging reduces the cost for locating a mobile terminal in the expense of an increase in the paging delay. We propose a selective paging scheme which significantly decreases the location tracking cost under a small increase in the allowable paging delay. We introduce an analytical model for the proposed location tracking mechanism which captures the mobility and the incoming call arrival patterns of each mobile terminal. Analytical results are provided to demonstrate the cost-effectiveness of the proposed scheme under various parameters     

An intra-LA location update strategy for reducing paging cost

The blanket paging strategy in current mobile networks may waste a lot of wireless bandwidth. While keeping the standard location area (LA) based location update (LU) strategy unchanged, we propose an intra-LA LU scheme to reduce the paging cost. While a mobile terminal (MT) is residing in an LA with a cell called anchor cell, where the MT usually stays for a significant period, an intra-LA LU is performed whenever the MT changes its location between the anchor cell and the rest of cells in the LA. For an incoming call, either the anchor cell or the rest of cells in the LA is paged to locate the MT. Thus the paging cost is greatly reduced, especially when the called MT is located in its anchor cell.     

A dynamic anchor-cell assisted paging with an optimal timer for PCS networks

An intra location area (intra-LA) location update (LU) scheme is proposed to increase paging accuracy for PCS networks. In the proposed scheme, each mobile terminal (MT) has a valid/invalid anchor-cell, which may be dynamically changed. A MT updates its anchor-cell information only when the status is changed, i.e., from the valid to the invalid or vice versa. Therefore, the intra-LA LU cost is minimized. Whenever the MT enters a cell, a timer is set. The MT realizes that the entered cell is its current anchor-cell if the timer expires before leaving the cell. An analytical model is proposed, and the optimal time threshold is derived explicitly.     

Optimal fractional movement-based scheme for PCS location management

In this letter, we propose a fractional movement-based location update scheme for personal communication service networks. Similar to the well-known fractional guard channel scheme for channel assignments, in our proposed scheme, the movement threshold is a real number with a fraction instead of an integer. We prove analytically that there is a unique optimal fractional movement threshold that minimizes the total cost of location updates and paging per call arrival.     

Module count-based overflow-control scheme for UMTS high-speed downlink packet access

In the universal mobile telecommunication system, the user equipment (UE) communicates with all cells in the active set through the air interface. Multiple radio links between the UE and the cells may reduce the transmission speed due to interference. In high-speed downlink packet access (HSDPA), only one serving cell is selected in the active set for high-speed downlink transmission. When the radio link quality between the serving cell and the UE degrades below some threshold, the best cell (in terms of the radio characteristics) in the active set is selected as the new serving cell and the UE switches from the old serving cell to the new serving cell. This action is referred to as frame synchronization. The frame-synchronization information may be delivered through more than one wireless transmission, which introduces long delay for the frame-synchronization process. In this paper, we propose an overflow-control scheme with module count for HSDPA, which guarantees that the frame-synchronization information is delivered through one wireless transmission and that when the UE switches wireless link to the new serving cell, no packet frames are lost.     

Resource reservation with pointer forwarding schemes for the mobileRSVP

We propose a pointer forwarding scheme for the mobile resource reservation protocol (MRSVP) to reduce the resource reservation cost on the wireless Internet. We show that the pointer forwarding scheme could significantly degrade the reservation cost when a mobile host performs locality movement     

Seamless Handoff Scheme Based on Pre-registration and Pre-authentication for UMTS–WLAN Interworking

Interworking issues between Universal Mobile Telecommunication System (UMTS) and Wireless Local Area Network (WLAN) have become a great matter of interest as an increasing number of mobile internet users require broadband wireless access to IP services in the wide area. In this paper, we present a practical UMTS–WLAN interworking architecture based on 3GPP standards and propose a seamless handoff scheme that guarantees low delay and low packet loss during UMTS–WLAN handoff. For low handoff delay, the proposed handoff scheme performs pre-registration and pre-authentication processes before layer 2 handoff. Moreover, it uses packet buffering and forwarding functions in order to reduce packet loss during the handoff period. On the above basis, detailed signaling procedures are presented, together with system requirements when a mobile terminal moves from UMTS to WLAN and vice-versa. Numerical results show that the proposed scheme performs well with respect to signaling cost, handoff delay, and packet loss compared with conventional schemes.     

LTE CSFB语音方案与性能分析

调查了业界关注的几种LTE语音方案现状,重点对目前运营商比较关注的CSFB语音方案进行了研究,包括CSFB信令流程和关键技术,例如联合附着、回落机制和MTRF等。最后针对各种回落机制对CSFB的性能影响进行了分析研究,结果表明当LTE回落到UMTS时,PS HO是最优方案,而当LTE回落到GSM网络时,R9 RRC Release with SIB是最优方案。     

Reducing overhead in movement based dynamic location management scheme for cellular networks

One of the key issues in cellular mobile communication is to find the current location of mobile terminal (MT) to deliver the services, which is called location management (LM). Much research has been done on dynamic LM that reduced the LM cost up to a large extent. In movement based dynamic LM scheme, the location area is defined in the form of ring of cells for individual user. Whenever an MT visits a cell outside of its current location area (LA), it triggers location update (LU). For this purpose, network must inform the mobile terminal about ID of all the cells present in its current location area. In this paper, a simple way of cell-ID assignment is proposed under which, network sends only the ID of center cell of LA ring to MT and then MT can compute IDs of all other cells in its location area. This saves a significant amount of wireless bandwidth by minimizing the signaling traffic at VLR level and thus reduces the mobility management overhead.     

带门槛的环形搜索移动性管理策略中移动台所 越过的位置区环数

位置管理或移动性管理是移动计算研究领域的一个具有挑战性的问题.我国及其他国家目前正在使用的个人通信网络如GSM、IS-41中,用两层数据库HLR/VLR支持位置管理.在这些网络中,每当移动台从一个位置区LA(Location area)移动到另一个位置区,其基本的位置管理策略(简称"基本策略")不管是否必要均立即进行位置更新操作,因而造成系统资源的极大浪费,降低了系统的性能.本文给出一种带门槛的环形搜索策略(简称"门槛环形策略")——将位置区分成环,设定一个门槛(整数),当移动台越过的位置区的环数没有达到门槛时,系统不进行位置更新操作,以减少位置管理的费用.在假定移动台的呼入是一个泊松过程,移动台在各个位置区的逗留时间是符合一般概率分布的随机变量的条件下,推导出在两次呼入之间移动台处于各位置区环的概率及移动台所越过的位置区环数公式,给出了"门槛环形策略"的位置管理费用小于"基本策略"的条件.     

基于强化学习的异构网络垂直切换方法

网络切换技术不仅可以保证用户的网络连接,同时能够以较强的信号传输网络数据。网络切换技术的性能对网络服务质量(quality of service, QoS)的影响至关重要。然而,现有的切换算法多数存在严重的乒乓效应,这不仅造成网络资源的严重浪费,还会损害用户的QoS。为此,提出了一种基于强化学习的异构网络垂直切换方案,主要从触发切换、网络选择及判决切换等方面进行优化。在触发切换时将垂直切换考虑成必要切换和择优切换,通过Q-Learning（QL）算法在选择网络时优化垂直切换;然后以QoS为条件,在判决切换时加入驻留定时器,从多角度减少用户切换次数,降低乒乓效应对异构网络垂直切换的影响。仿真结果表明,基于强化学习的异构网络垂直切换方法可以在保证QoS的条件下有效减少用户切换网络的次数,短时间内频繁切换的情况也有所改善,降低了乒乓效应的影响。     

Mitigating location management traffic via aggregation in multi-hop cellular networks

In high mobility areas such as shopping malls and transportation stations, mobile users tend to move in and out in a bursty fashion, and hence location update (LU) and paging signaling cause substantial traffic burden to the cellular networks, leading to signaling congestion. This poses a great challenge to the system design for wireless cellular systems. Traditional cellular systems cannot cope with this situation very well. However, with the ad hoc operational mode recently introduced into the cellular systems, the added multi-hop relaying via mobile devices provides a new way to mitigate location management traffic. In this paper, based on this new architecture, we propose a novel scheme, called aggregative location management, which aggregates multiple location updates into group location updates. For the scenarios of high capacity transit (HCT) systems, we use this grouping scheme to alleviate the signaling traffic when mobile users in an HCT move into new location areas. For other scenarios with mass arrivals of LU requests, we develop a generic aggregative location management scheme in which LU requests can be first aggregated by designated mobile devices and then are periodically sent to the location registers. Performance evaluation is carried out and shows their significant effectiveness.     

An enhanced channel-quality indication (CQI) reporting scheme for HSDPA systems

A major evolution of UMTS standard is the high speed downlink packet access (HSDPA). One of key techniques supporting HSDPA is the adaptive modulation and coding (AMC) in which the modulation scheme and the coding rate are adaptively changed according to the downlink channel quality reported by the user equipment (UE). Therefore, the channel quality indication (CQI) reporting scheme is directly related to the accuracy of AMC and the performance of HSDPA. This letter proposes an enhanced CQI reporting scheme that can be used when a proportional fair scheduling algorithm (PFA) is used as a packet scheduling algorithm. The proposed scheme uses a dynamic threshold to filter off redundant CQI reports. With the proposed scheme, the battery capacity of UK can be conserved, maintaining the performance of traditional CQI reporting scheme.     

具有指定接收组门限共享验证签名加密方案

本文提出了一个具有指定接收者验证的签名加密方案.该方案是数字签名与公钥密码体制的有机集成.与普通数字签名方案相比,除了具有认证性、数据完整性外还具有保密性和接收方的隐私性.然后又利用门限方案构造了一个(t,n)门限共享验证签名加密方案.与现有的门限共享验证签名加密方案相比具有数据传输安全、通信代价更小、执行效率更高、能够确切地检查出哪个验证者篡改子密钥等特点.     

Designing power aware self-reconfiguring topology for mobile wireless personal area networks using fuzzy logic

In mobile wireless personal area networks (WPAN), the position of each node changes over time. A network protocol that is able to dynamically update its links in order to maintain strong connectivity is said to be "self-reconfiguring." We propose a mobile wireless personal area networks (WPAN) design method with self-reconfiguring protocol for power efficiency. The WPAN is self-organized to clusters using an unsupervised clustering method, fuzzy c-means. A fuzzy logic system is applied to master/controller election for each cluster. A self-reconfiguring topology is proposed to manage the mobility and recursively update the network topology. We also modify the mobility management scheme with hysteresis to overcome the ping-pong effect. Simulation results show that our scheme performs much better than the existing algorithm.