Nitul Dutta

Interoperability of WiFi and WiMAX

The aim of this paper is to explore the two most popular wireless networks IEEE 802.11 and IEEE 802.16 with a view to examine the challenges and issues involved in the integration of both the networks. The 802.11 or Wireless Fidelity (WiFi) is a low cost wireless access technology that supports low data rate within a short range. On the contrary, the IEEE 802.16 or WiMAX (Worldwide Interoperability for Microwave Access or) is a costly network that support a data rate of 70Mbps within the range of 50km. To provide guaranteed and satisfactory service quality with moderate cost in wireless environment, integration of the two network technology is necessary. The difference in the MAC layer protocol and routing mechanism the interoperability of the two networks are challenging. In this paper, a brief discussion on WiFi and WiMAX issues are carried out, and investigated various methods and challenges for interoperation of WiFi and WiMAX technology.

An Improved Cluster Maintenance Scheme for Mobile AdHoc Networks.

Cluster based routing in Mobile AdHoc Networks (MANETs) improves performance of routing by maintaining route information within a cluster head (CH). However, due to the movement of CH, new CHs are required to be selected from time to time and hence introduce additional overhead. If the frequency of CH changing could be reduced then the cluster based routing would be a better choice for routing in MANETs. This paper proposes an Improved Cluster Maintenance Scheme (ICMS) primarily focused on minimizing frequency of CH changing process. The proposed method makes cluster more stable. The proposed ICMS is simulated in ns-2 and simulation result is compared with Least Cluster head Change (LCC), (CBRP) and Incremental Maintenance Scheme (IMS) in conditions of clustering overhead, cluster member and cluster head changing by applying different range of speed and pause time for all mobile nodes. The simulation results show that ICMS perform better over LCC, CBRP and IMS.

A probability based stable routing for cognitive radio adhoc networks

Cognitive Radio is devised as a wireless communication technology that enables user to communicate without having a fixed pre assigned radio spectrum. The technology facilitates the utilization of temporarily unused portion of radio frequency in the licensed spectrum region. Since its invention, researchers have carried out their investigation in various directions like spectrum sensing, spectrum allocation, routing etc. In this paper, a routing mechanism is proposed for cognitive radio adhoc network named as proposed stable routing (PSR). The proposed algorithm constructs path from source to destination considering the probability of stability of the selected channel. The channel is considered stable if the probability that the channel would be claimed by the concerned primary user during the operation of secondary user is comparatively low. PSR is simulated in ns-2 and compared with Cognitive AODV (CAODV) protocol. Observation shows that PSR outperforms CAODV in terms of route survival time, routing overhead and packet loss rate.

A stable route selection algorithm for Cognitive Radio Networks

In this paper, a route selection mechanism for cognitive radio network (CRN)is proposed where the route construction process selects only those channels which have the maximum probability of being stable. By the term stable channel, we mean that the channel will not be claimed by primary users (PUs) frequently. A probabilistic approach for finding the steady channel is adopted where an initial state probability is considered based on the previous channel availability history. A set of algorithms are proposed in the paper to implement the route selection method in CRN and simulated in ns-2.Routing overhead, packet loss rate and route sustainability parameters with respect to the proposed protocol, show improvement over Cognitive AODV (CAODV).

A SINR Based Clustering Protocol for Cognitive Radio Ad Hoc Network (CRAHN)

A novel clustering approach for cognitive nodes in CRN based Ad Hoc Networks (CRAHNs) is proposed in this paper. The Signal to Interference plus Noise Ratio (SINR) produced by Primary Users (PUs) on collocated Cognitive Users (CUs) along with Expected Transmission Time (ETT) among CUs is taken into account in order to form the clusters. The operation of CUs, either during cluster formation or data transmission no way harms the ongoing transmission of PU. The main aim here is to find suitable method of cluster formation so that the findings of this work can be used for developing efficient cluster based routing protocol for CRAHN. A medium scale network with up to 200 CUs are taken for experiment and some reasonable values for influential parameters are presented here.

A routing protocol for cognitive networks in presence of co-operative Primary User

In Cognitive Radio Network (CRN) Cognitive Users (CUs also called Secondary Users (SUs)) make use of frequency band used by Primary Users (PUs) in an opportunistic way. Routing in CRN is a challenging job because the packets within SUs need to be routed only when channels of PUs are idle. The CRN routing protocols proposed so far, does not assume that the PUs will take part in the route formation of SUs in the environment. In this paper we present a routing mechanism for CRN where some of the PUs will forward packets for Cognitive Users (CU) during their idle time. But before including the PUs in the path between any two SUs, PUs must express their willingness to forward packets. These PUs that agree to forward packets for SUs are named as cooperative PU (CPU). The proposed protocol is an extension of Cognitive Ad-hoc On-demand Distance Vector (CAODV) protocol to work in presence of co-operative PUs. The protocol is simulated in ns-2 and compared with CAODV. Result shows a significant improvement in packet loss rate and end-to-end delay over CAODV.

Three Layer MIPv6 (TLMIPv6): A new mobility management protocol for IPv6 based network

Uninterrupted connectivity on move is a primary demand of end users both in cellular and IP based networks. Protocols that assist to maintain continuous link despite of frequent change in point-of attachment of mobile devices are called mobility management protocol. Although the mobility management protocols are matured enough in cellular network it is in a growing phase for IP based network. In this paper a new mobility management scheme called Three Layer MIPv6 (TLMIPv6) is proposed and comparative performance evaluation is carried out with MIPv6 and HMIPv6 protocol using simulation in ns-2 environment. The intention of this work is to analyze these three protocols and to find suitable scenario for each of these protocols.

Fluid Flow and Random Walk Mobility Model for Wireless Mobile Network Research: A Review

In performance evaluation of mobility management protocols for Wireless Mobile Networks (WMN) estimating cell change rate of mobile users is very important. Based on the rate of cell change (also called handoff rate) other parameters such as location update cost, handoff latency etc. may be calculated. Moreover, any new mobility management protocol must be examined either mathematically or through simulation before its use in real network. Since the cell change rate is dependent on movement pattern of users; that is why modeling of user movement in order to evaluate the performance of protocols and architectures for WMN plays a vital role. The aim of this paper is to discuss Fluid Flow and Random Walk mobility and different method to estimate cell changing rate using these two models. Our intention is to support researchers with options to choose a suitable model when their protocol or architecture needs to be studied under various mobility patterns.

Mobile solutions in small and medium enterprises

The paper concerns the problem of using and implementing mobile solutions in SMEs (Small and Medium Enterprises). Some of the existing examples of mobile solutions are analyzed and characterized. A significant part of the paper is a presentation of the research on mobile solutions which can be used to manage the business activities in SMEs. The role and methods of testing the mobile systems have been presented. A significant part of paper concerns the research on using mobile solutions in SMEs. Additionally, the article contains information related to the direction of development of mobile solutions in SMEs in particular: mobile Business Intelligence, business tourism. The work ends with short conclusions.

Grid based routing in cognitive radio networks for concurrent communication

Cognitive Radio Network (CRN) exploits the spectrum hole in licensed bands by allowing co located cognitive users to communicate among themselves when licensed users are idle. In such opportunistic communication, the cognitive users need to vacate the channel as and when the licensed user becomes active. Most of the time such sudden termination of ongoing sessions of cognitive devices leads to unacceptable overhead and degrades service quality. So, in this paper a new routing protocol is proposed which emphasizes on concurrent communication of cognitive users rather than opportunistic communication. In concurrent communication cognitive devices are allowed to communicate even in the presence of licensed users activity by controlling the transmission power of cognitive devices such that they do not interfere with the ongoing conversation of licensed users. The algorithm is based on the full location information with the assumption that each of the cognitive device can detect the location information of its own and any other cognitive device in the network. All cognitive devices are arranged into grid cells and every grid selects a grid Head (gH) based on some predefined criteria who takes care of routing. Further, the protocol also suggests a routing zone and forwarding region based on the location of the destination in order to reduce routing overhead and faster route establishment. The simulated results of the protocol is compared with CAODV protocol and observed an improvement in packet delivery ratio and routing overhead.