KwangJin Park

A Comparative Analysis on the Signaling Load of Mobile IPv6 and Hierarchical Mobile IPv6: Analytical Approach*This research was supported by University IT Research Center Project.

This paper presents a novel analytical approach to evaluate the signaling load of Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6). Previous analytical approaches for IP mobility management have not provided a complete and general framework for the performance analysis; no consideration of either periodic binding refresh cost or extra packet tunneling cost from the viewpoint of IP mobility management, and no in-depth investigation with respect to various system parameters. In this paper, according to the proposed analytical approach, we derive the location update costs (i.e., the sum of binding update costs and binding refresh costs), packet tunneling costs, inside-domain signaling costs, outside-domain signaling costs, and total signaling costs, which are generated by a mobile node (MN) during its average domain residence time in case MIPv6 or HMIPv6 is deployed under the same network architecture, respectively. Moreover, based on these derived costs, we evaluate the impacts of various system parameters on the signaling costs generated by an MN in MIPv6 and HMIPv6. The aim of this paper is not to determine which protocol performs better, but evaluate the performance that can be expected for each protocol under the various conditions, broaden our deep understanding of the various parameters that may influence the performance, and provide insight for the deployment of the two protocols.

Adaptive data dissemination schemes for location-aware mobile services

Broadcasting is the natural method of propagating information in wireless links, which guarantees scalability in the case of bulk data transfers. It is particularly attractive for resource limited mobile clients in asymmetric communications. To facilitate power saving via wireless data broadcast, index information is typically broadcast along with the data. By first accessing the broadcast index, the mobile client is able to predict the arrival time of the desired data. However, it suffers from the drawback that the client has to wait and tune for an index segment, in order to conserve battery power consumption. In location-aware mobile services (LAMSs), it is important to reduce the query response time, since a late query response may contain out-of-date information. This paper proposes a new broadcast-based spatial query processing method, called BBS designed to support NN query processing. In the BBS, broadcasted data objects are sorted sequentially based on their locations, and the server broadcasts the location dependent data along with an index segment. In this method, since the data objects broadcasted by the server are sequentially ordered based on their location, it is not necessary for the client to wait for an index segment, if it has already identified the desired data items before the associated index segment has arrived. The performance of this scheme is investigated in relation to various environmental variables, such as the distributions of the data objects, the average speed of the clients and the size of the service area.

An efficient data dissemination schemes for location dependent information services

Location dependent information services (LDISs) produce answers to queries according to the location of the client issuing the query In LDIS, techniques such as caching, prefetching and broadcasting are effective approaches to reducing the wireless bandwidth requirement and query response time However, the clients mobility may lead to inconsistency problems In this paper, we introduce the broadcast-based LDIS scheme (BBS) for the mobile computing environment In the BBS, broadcasted data items are sorted sequentially based on their location and the server broadcasts the location dependent data (LDD) along with an index segment Then, we present a data prefetching scheme and OBC (Object Boundary Circle), in order to reduce the query response time The performance of the proposed scheme is investigated in relation to various environmental variables, such as the distributions of the data items, the average speed of the clients and the size of the service area.

Broadcasting and prefetching schemes for location dependent information services

The results of location-dependent queries(LDQ) generally depend on the current locations of query issuers. Many mechanisms, such as broadcast scheme, prefetching scheme, or caching scheme have been developed to improve system performance and provide better service for location dependent information services(LDISs). However, the clients mobility may lead to inconsistency problems. In this paper, we introduce the broadcast-based LDIS scheme(BBS) in the mobile computing environment. In the BBS, broadcasting data items are sorted sequentially based on their location and the server broadcasts the location dependent data(LDD) without additional indices. Then we present a data prefetching scheme and OBC(Object Boundary Circle) in order to reduce the clients tuning time. The performance for the proposed scheme is investigated by various environmental variables such as distributions of the data items, average speeds of the clients and the size of the service area.

On the design of energy-efficient location tracking mechanism in location-aware computing

The battery, in contrast to other hardware, is not governed by Moores Law. In location-aware computing, power is a very limited resource. As a consequence, recently, a number of promising techniques in various layers have been proposed to reduce the energy consumption. The paper considers the problem of minimizing the energy used to track the location of mobile user over a wireless link in mobile computing. Energy-efficient location update protocol can be done by reducing the number of location update messages as possible and switching off as long as possible. This can be achieved by the concept of mobility-awareness we propose. For this purpose, this paper proposes a novel mobility model, called state-based mobility model (SMM) to provide more generalized framework for both describing the mobility and updating location information of complexly moving objects. We also introduce the state-based location update protocol (SLUP) based on this mobility model. An extensive experiment on various synthetic datasets shows that the proposed method improves the energy efficiency by 2 ∼ 3 times with the additional 10% of imprecision cost.

Continuous spatial queries via wireless data broadcast

This paper proposes a generic framework for continuous range queries via wireless data broadcast. This framework distinguishes itself from existing work by being the first to address the continuous spatial query issue, without an index, making effective use of the low wireless bandwidth, and therefore being ideal for achieving maximal scalability with the fastest access time. The task of the query processor is to selectively monitor the wireless broadcast channel, as the data items are disseminated according to their location by the server.

Client-side caching for nearest neighbor queries

The Voronoi diagram (VD) is the most suitable mechanism to find the nearest neighbor (NN) for mobile clients. In NN query processing, it is important to reduce the query response time, since a late query response may contain out-of-date information. In this paper, we study the issue of location dependent information services (LDISs) using a VD. To begin our study, we first introduce a broadcast-based spatial query processing methods designed to support NN query processing. In further sections, we introduce a generic method for location-dependent sequential prefetching and caching. The performance of this scheme is studied in different simulated environments. The core contribution of this research, resides in our analytical proof and experimental results.

Effective low-latency k-nearest neighbor search via wireless data broadcast

To facilitate power saving via wireless data broadcast, index information is typically broadcast along with the data. By first accessing the broadcast index, the mobile client is able to predict the arrival time of the desired data. However, it suffers from the drawback that the client has to wait and tune for an index segment, in order to conserve battery power consumption. Moreover, the average time elapsed between the request for the data and its receipt may increase as a result of these additional messages. In this paper, we present a broadcast-based spatial query processing method designed to support K-NN(K-Nearest Neighbor) queries via wireless data broadcast. With the proposed schemes, the client can perform NN query processing without having to tune into an index segment. Experiments are conducted to evaluate the performance of the proposed methods. The resulting latency and energy consumption are close to the optimum values, as the analysis and simulation results indicate.

Nearest neighbor queries for r-trees: why not bottom-up?

Given a query point q, finding the nearest neighbor (NN) object is one of the most important problem in computer science. In this paper, a bottom-up search algorithm for processing NN query in R-trees is presented. An additional data structure, hash, is introduced to increase the pruning capability of the proposed algorithm. Based on hash, whole data space is disjointly partitioned into n × n cells. Each cell contains the pointers of leaf nodes which intersect with the cell. The experiment shows that the proposed approach outperforms the existing NN search algorithms including the BFS algorithm which is known as I/O optimal algorithm.

Location-based caching scheme for mobile clients

The Voronoi Diagram(VD) is the most suitable mechanism to find the nearest neighbor(NN) for mobile clients. In NN query processing, it is important to reduce the query response time, since a late query response may contain out-of-date information. In this paper, we study the issue of location dependent information services(LDISs) using a VD. To begin our study, we first introduce a broadcast-based spatial query processing methods designed to support NN query processing. In further sections, we introduce a generic method for location-dependent sequential prefetching and caching. The performance of this scheme is studied in different simulated environments. The core contribution of this research, resides in our analytical proof and experimental results.