Movement-based Scheme Research Articles

The Effectiveness of Classification-Specific Physical Therapy for People with Low Back pain Within Dominant Movement-Based Schemes: A Systematic Review

Background Identification of homogenous subgroups of patients with low back pain (LBP) and classification-based treatment have been recommended by some researchers and primary care clinicians. However, evidence regarding the effectiveness of this approach is not conclusive; one reason for this controversy appears to be the heterogeneity of trials in this context..Methods The aim of this study was to determine the effectiveness of classification-specific physical therapy in patients with LBP. The included trials were investigated in more homogeneous categories with respect to their classification scheme. Electronic databases including Medline, Cochrane, Ovid, Scopus, and PEDro were searched systematically for English-language randomized controlled trials (RCTs), published from 1980 to October 3, 2015. We included studies on LBP cases, which aimed to compare classification-specific physical therapies with non-specific treatments lacking patient classification. PEDro scoring was used to check the quality of the included trials, and the GRADE approach was used to evaluate the overall quality of evidence. Data on participants’ characteristics, sample size, and inclusion/exclusion criteria were extracted to obtain an overview of the included RCTs..Results A total of 12 RCTs were identified and categorized into four classification schemes. Some evidence supporting classification-specific treatment was found in each of the schemes. However, the reported evidence was conflicting predominantly due to differences in the study design. Also, GRADE quality assessment indicated the low quality of evidence for both approaches..Conclusions Categorization of trials based on their classification scheme to investigate the efficacy of classification-based physical therapy could reduce the heterogeneity of trials and allow researchers to understand the contradictory results in this context..

Modeling and Cost Analysis of Movement-Based Location Management for PCS Networks With HLR/VLR Architecture, General Location Area and Cell Residence Time Distributions

Location management plays a central role in guaranteeing the effective operation of personal communication service (PCS) networks. In current PCS networks, a two-tier system of home location register (HLR) and visitor location register (VLR) databases is commonly used for location management. To improve the performance of PCS networks, several dynamic location management schemes have been proposed. Among the existing dynamic schemes, the movement-based location management may be the most practical due to its effectiveness and easy implementation under the framework of current PCS networks. To implement location management in PCS networks, cost analysis is a crucial aspect. However, most of the existing cost analyses for the movement-based scheme are too simple and not available for PCS networks with the HLR/VLR architecture. One reason for this is the complexity and the difficulty associated with the problem. Li et al. and Rodriguez-Dagnino et al. challenged this task by considering the HLR/VLR architecture. However, the cost analysis developed by Li et al. was carried out under the assumption that the cell and location area (LA) residence times are exponentially distributed. Rodriguez-Dagnino et al. furthered Li et al.'s work by assuming that the LA residence time follows a hyperexponential distribution and that the cell residence time is generally distributed. However, Li et al. and Rodriguez-Dagnino et al. failed to consider VLR location updates that are caused by terminal movements between LAs. In this paper, we relax the restrictions imposed on the distributions of the cell and LA residence times and propose an analytical model to study the movement-based scheme with HLR/VLR architecture. The issue of VLR location updates that are caused by movements between LAs is addressed carefully and successfully. Analytical formulas for the costs of HLR and VLR location updates are derived using a unified approach. Numerical study suggests that the total cost is a convex function of the movement threshold and is sensitive to the variances of the cell and LA residence times. The result presented in this paper can serve as a guideline for the system design and the implementation of the movement-based scheme for PCS networks.

Movement-Based Location Management for General Cell Residence Times in Wireless Networks

Location management of mobile users is of primary importance in personal communication networks (PCNs), and it is mainly aimed to facilitate the delivery of incoming calls to destination users and to make a more efficient use of network resources. In practical PCNs, the location management algorithms need to keep track of mobile users in a dynamic manner, and it is a design concern to minimize the generated signaling traffic. In this paper, we present the cost analysis for the dynamic movement-based location update scheme. Our model is based on renewal theory arguments, and it is general enough to include a variety of probability distributions for modeling cell residence times (CRTs) in hyperexponentially distributed location area residence times and exponentially distributed intercall times. We compare the location update cost for the dynamic and static schemes. We present numerical results regarding the exponential and circular CRT distributions and discuss the optimal threshold distance for location update that minimizes the cost of the dynamic movement-based scheme.

Optimization of Sequential Paging in Movement-Based Location Management Based on Movement Statistics

The movement-based scheme is a dynamic location management (LM) scheme that is particularly easy to implement. Each mobile simply counts the number of cell-boundary crossings and initiates location update when this number exceeds the predefined movement threshold. Although its LM cost is inferior to that of distance-based schemes, this cost can be decreased by sequential paging methods that take into account mobiles' movement statistics. In this paper, we derive the probability distribution of a mobile's number of cell-boundary crossings during the interval between two location registrations in a movement-based LM scheme for Poisson call arrivals and generally distributed cell residence time. Based on the derived statistics, we obtain the optimal movement threshold and develop an optimal sequential paging scheme. Numeric results are presented to show that the proposed optimal sequential paging scheme outperforms existing sequential paging schemes over a wide range of call-to-mobility ratios

Modeling location management in wireless networks with generally distributed parameters

In the wireless mobile networks, location update (LU) and paging are two basic operations in the framework of mobility management. The trade-off analysis between LU and paging is traditionally performed under the assumption that the key variables follow exponential distribution. However, recent work showed that such assumptions may be incorrect. In this paper, by introducing the concept of LU inter-arrival time and additionally relaxing the assumptions for the inter-service time, cell residence time and LU inter-arrival time, we present an analytical technique to develop the closed-form formula for the signaling cost applicable to different location management schemes. Specifically, the result is applied to the static scheme and the dynamic movement-based scheme to demonstrate the general applicability. Illustrative numerical examples are given to compare the location management scheme performance based on the cell characteristics.

Design and analysis of location management for 3g cellular networks

Location management is a key issue in personal communication service networks to guarantee the mobile terminals to continuously receive services when moving from one place to another. We study two location management schemes, a dynamic movement-based scheme (DYNAMIC-3G) and a static scheme (STATIC-3G), for 3G cellular networks where home location registers, gateway location registers (GLRs), and visitor location registers form a three-level hierarchical mobility database structure. For both schemes, the cost functions are formulated analytically. We prove that there is an optimal movement threshold that minimizes the total cost function of DYNAMIC-3G and propose a binary search algorithm to find the optimal threshold. Furthermore, we present performance evaluation and comparison of the proposed schemes with the previous schemes in 2G cellular networks where the GLR is not present. Our studies validate the optimality of the DYNAMIC-3G scheme and show that the proposed schemes outperform the previous schemes, especially when the remote-local-cost ratio is high. The comparison results between DYNAMIC-3G and STATIC-3G indicate that DYNAMIC-3G should be adopted when the mobility rate is low, and STATIC-3G should be adopted otherwise. Furthermore, DYNAMIC-3G tends to perform better than STATIC-3G when the paging cost is high or the number of cells in a location area is large.

Optimal location management for two-tier PCS networks

One of the most important issues in Personal Communication Service (PCS) networks is location management, which keeps track of the Mobile Terminals (MTs) moving from place to place. In this paper, we analytically derive cost functions of location updates and paging for a dynamic movement-based location management scheme for PCS networks with two-tier mobility databases. We prove analytically that there is a unique optimal movement threshold that minimizes the total cost of Home Location Register location updates, Visitor Location Register location updates, and paging, per call arrival. An effective algorithm is proposed to find the optimal movement threshold. Furthermore, we propose a hybrid location management scheme, in which when the call-to-mobility ratio is larger than a threshold, the optimal dynamic movement-based scheme is adopted. Otherwise, the static location update is adopted. The Newton approximation method is adopted to find this threshold. Our study shows that the proposed hybrid scheme outperforms both the dynamic movement-based scheme and the static location update scheme.

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.

An efficient recovery scheme for fault-tolerant mobile computing systems

This paper presents an efficient recovery scheme to provide fault-tolerance for the mobile computing systems. The proposed scheme is based on the message logging and the independent checkpointing, and for the efficient management of the recovery information, such as checkpoints and message logs, the movement-based scheme is suggested. The mobile host carrying its recovery information to the nearby mobile support station can recover instantly in case of a failure. However, the support stations visited by the mobile host may have to experience the high failure-free execution cost for transferring the recovery information and accessing the stable storage. On the other hand, the recovery cost can be too high, if the recovery information remains dispersed over a number of mobile support stations. The movement-based scheme considers both of the failure-free execution cost and the failure-recovery cost. Hence, while a mobile host moves within a certain range, the recovery information of the mobile host remains at the support stations where the information was first saved. However, if the mobile host moves out of the range, it transfers the recovery information into the nearby support station. As a result, the scheme can control the transfer cost as well as the recovery cost. The performance of the proposed scheme is evaluated with extensive simulation study.

A location-based mobility tracking scheme for PCS networks

This paper introduces a location-based locating strategy for Personal Communication Services (PCS) systems. In the proposed scheme, location updates are based on the value of a movement counter. The update of the movement counter is based on information on the locations visited by a mobile terminal (MT) since the last location update. In particular, the cell identifiers and the corresponding movement counter values are maintained in the MT for a part of the visited cells since the last location update. When the MT enters a cell whose identifier is not stored in the MT, the movement counter increases by one. If the movement counter reaches the update threshold, a location update is triggered; otherwise, the cell identifier and the corresponding movement counter value are stored in the MT. When the MT enters a cell whose identifier is in the MT, the movement counter is assigned with the counter value kept in the MT for this cell, and all cells with greater counter values in the MT are removed. The proposed scheme allows the dynamic selection of the update threshold according to each user's calling and mobility patterns. Analytical and simulation models have been developed to compare the proposed scheme with both the movement-based scheme and the distance-based scheme. Results demonstrate that when the call-to-mobility ratio (CMR) is low, the proposed scheme can achieve a significant cost reduction compared to the movement-based scheme. For example, when the CMR is 0.01, a savings of around 25% in the optimal total cost per call arrival is achieved with the proposed scheme. Moreover, the proposed scheme is easier to implement than the distance-based scheme.

Cost reduction in location management using semi-realtime movement information

This paper introduces a dynamic paging scheme based on the semi-realtime movement information of an individual user, which allows a more accurate predication of the user location at the time of paging. In general, a realtime location tracking scheme may require complex control schemes and incur unacceptably high computation and messaging cost. Our proposed approach, namely the velocity paging scheme, relaxes the realtime constraints to semi-realtime to provide a good combination of cost reduction and ease of implementation. The proposed velocity paging scheme utilizes semi-realtime velocity information, namely velocity classes, of individual mobile terminals and dynamically calculates a paging zone (a list of cells to be paged) for an incoming call. Therefore, the total paging cost can be reduced due to the paging area reduction. Much consideration also has been given to reduce the complexity of the proposed scheme. As a result, it only requires minimal extra overhead and is feasible to implement in current cellular/PCS networks. The velocity paging can be combined with the movement-based registration or other registration schemes. Analytical and simulation results of the velocity paging and movement-based registration combination are provided to demonstrate the cost effectiveness of the scheme under various parameters in comparison with the location area scheme.