Sulata Mitra

Challenges of computing in mobile cellular environment-a survey

Advances in cellular mobile technology have engendered a new paradigm of computing, called mobile computing. The frequency spectrum allocated to this service is not sufficient with respect to enormous growth of mobile communication users. Tracking down a mobile user in a cellular network which is a collection of geometric areas called cells each serviced by a base station is the other concern to the designer. This service also needs another problem to be solved, that is the access of common information by mobile users. Other than the issues in existing technology, many other issues on developing technology need to be addressed. The survey is done in two phases. In the first phase a survey of three fundamental problems in mobile computing on existing technology is done. The issues discussed arise from three essential requirements: the efficient management and sharing of the spectrum among the users; to locate a mobile user in the cellular mobile environments; and processing of queries on location dependent data. The second phase highlights on research on different issues such as security, routing etc. in third generation wireless network in developing technology.

Identification, Authentication and Tracking Algorithm for Vehicles Using VIN in Centralized VANET

The VANET should allow only the authentic vehicles to participate in the system for efficient utilization of its available resources. The proposed system architecture contains multiple base stations in the coverage area of a certifying authority. The base station verifies the identification of the vehicle and the certifying authority verifies the authentication of the vehicle using its vehicle identification number. The certifying authority also generates a digital signature for each authentic vehicle and assigns it to the corresponding vehicle through base station. The base station allocates a channel to each authentic vehicle. The channel remains busy as long as the vehicle is within the coverage area of this base station. So the base station is able to track an authentic vehicle by sensing the allocated channel within its coverage area.

A load balancing strategy using dynamic channel assignment and channel borrowing in cellular mobile environment

A simple load balancing technique is proposed. It is basically a combination of both the dynamic channel assignment and channel borrowing techniques. All the cells of the system are divided into six groups, each group under one mobile switching centre (MSC). Initially a fixed number of channels are assigned to each cell under each mobile switching centre. Finally the channels are distributed among the cells as per their requirement. In the case of sudden channel demand under one mobile switching centre, the cell which needs more channel can borrow a channel from one of its compact pattern cells belonging to the same group (to be defined) with it by exchanging a negligible number of messages among the different components of the network. If there is no probable lender cell in the group, the MSC of the borrower cell can lend it from another MSC.

A varying per user profile based location update strategy for cellular networks

In the present work, a profile based location management scheme is proposed. The proposed scheme considers each users profile which varies from time to time. It maintains a database where the profile of each user is stored every /spl tau/ units of time. The algorithm treats every user either as LFPC (less frequent profile changer) or FPC (frequent profile changer) depending on its profile for the last /spl tau/ units of time. Cost estimation with this scheme is also done which shows only database updating cost as paging is confined to only one cell. Exhaustive simulation work is done to study the variation of updating cost with different parameters. Finally a comparison is also made between the present scheme and a scheme where no categorization like LFPC or FPC is made.

Congestion control by dynamic sharing of bandwidth among vehicles in VANET

The wireless access in vehicular environment system is developed for enhancing the driving safety and comfort of automotive users. However, such system suffers from quality of service degradation for safety applications caused by the channel congestion in scenarios with high vehicle density. The present work is a congestion control mechanism in vehicular ad-hoc network. It supports the communication of safe and unsafe messages among vehicles and infrastructure. Each node maintains a control queue to store the safe messages and a service queue to store the unsafe messages. The control channel is used for the transmission of safe messages and service channel is used for the transmission of unsafe messages. Each node computes its own priority depending upon the number of waiting messages in control queue and service queue. Each node reserves a fraction of control channel and service channel dynamically depending upon the number of waiting messages in its queue. The unsafe messages at a node may also be transmitted using control channel provided the control channel is free and service channel is overloaded which helps to reduce the loss of unsafe message at a node which in turn reduces the congestion level of a node and also improves its quality of service. The available bandwidth is also distributed among the nodes dynamically depending upon their priority. The performance of the proposed scheme is evaluated on the basis of average loss of unsafe message, average delay in safe and unsafe message, storage overhead per node.

Optimal network selection algorithm for heterogeneous wireless networks

Future wireless network must be able to coordinate services within a diverse network environment. One of the challenging problems for coordination is the selection of optimal network depending upon the type of demanding application. There are different types of Internet applications and network interfaces. The quality of service requirement varies from one application to another. The present work considers the integration of three networks, GPRS, IEEE 802.11x and WiMAX. The proposed scheme uses network selection module to select network dynamically depending upon the application type. It also uses a traffic distribution module to distribute the applications dynamically among the various routes within a network. The traffic distribution module also detects the fast handoff mobile nodes and triggers vertical handoff for such mobile nodes to a network having high data rate to prevent their further handoff. This module also calculates network performance parameters and application blocking probability of the network. It also sends the network performance parameters and application blocking probability to network selection module. The network selection module uses the network performance parameters to execute the network selection algorithm and application blocking probability of each network to determine the user satisfaction. The performance of the proposed scheme is evaluated on the basis of network usage, application blocking probability and user satisfaction.

Communication Void Free Routing Protocol in Wireless Sensor Network

Communication voids have negative effect on real time routing protocols. Hence it needs to design an energy efficient communication void free routing protocol for wireless sensor network. A clustering and routing protocol is proposed in the present work. The proposed clustering algorithm is the combination of cluster head selection algorithm and cluster member selection algorithm. The proposed routing algorithm establishes an energy efficient communication void free route for delivering the sensed data to the base station. Both clustering and routing algorithm outperform the existing algorithms in terms of energy consumption and execution time of clustering algorithm, energy consumption, energy dissipation and transmission delay of routing algorithm.

On location tracking and load balancing in cellular mobile environment-a probabilistic approach

The present work addresses probabilistic solution of two fundamental issues of cellular mobile environment maintaining a common set of information. One of the issues is to predict the location of a mobile user whereas the other is to predict the traffic load of each area and accordingly distribute channels among different areas. For location management the entire area covered by cellular architecture is considered as a hierarchy of location areas considering mobile switching centre as the root of the hierarchy and thus a new tree like data structure is introduced. When a call arrives, mobile switching centre computes the location probability of the called mobile unit at all the cells under it with the help of a database and tree-like data structure is kept in mobile switching centre itself. Finally mobile switching centre performs the appropriate searching to find the best probable cell(s) where the desired mobile unit may be traced. The scheme is made more realistic later exploiting the fact that most of the users confine their movement within a group of cells. It is done by making leaf level of the hierarchy dynamic by switching the membership of a cell from one group to the other depending upon the change of probability of finding a user at a cell. For predicting traffic load in each cell, mobile switching centre scans the same database used for predicting the location of a mobile user and finds out frequency of locating the user in each cell. With the help of this information and a heuristic function the cell wise channel requirement is computed. Finally experiments are carried out to see the variation of system cost and delay with time considering call arrival pattern as Poisson distribution and movement pattern by Gaussian distribution.

Seamless mobility management and QoS support for multihomed mobile node in heterogeneous wireless networks

In the next generation wireless network a mobile node will be multihomed to utilize multiple wireless access technology simultaneously. The seamless mobility management and quality of service support are the challenging issues for such a heterogeneous wireless network. Each multihomed mobile node has multiple care of addresses corresponding to multiple network interfaces associated with it. An address server is maintained in the proposed scheme to provide a suitable care of address of any desired multihomed mobile node to a corresponding node for session initiation which in turn helps to achieve seamless mobility and to balance the load among the various network interfaces. A connection set up module is maintained in the proposed scheme to establish a connection depending upon the availability of network capacity, the priority of waiting connection and the user satisfaction which in turn helps to improve the quality of service per user in terms of user satisfaction. The performance of the proposed scheme is evaluated in terms of the percentage of network usage, delay per network interface, application blocking probability per traffic class and user satisfaction.

Policy based admission control and handoff decision algorithm for next generation All-IP wireless network

The present work is a policy based admission control algorithm and handoff decision algorithm for next generation all-IP wireless network. It uses policy based admission control algorithm to admit a new call and policy based handoff decision algorithm to admit a handoff call. The proposed scheme also uses the network initiated vertical handoff algorithm to perform load balancing, to maximize battery power life time of a mobile node, to minimize power consumption, system delay and loss of packet, and finally to maximize the throughput of the network. Results based on a detailed performance evaluation study are also presented to demonstrate the efficacy of the proposed scheme.