Tapas Jana

Minimization of Handoff Failure Probability for Next-Generation Wireless Systems

During the past few years, advances in mobile communication theory have enabled the development and deployment of different wireless technologies, complementary to each other. Hence, their integration can realize a unified wireless system that has the best features of the individual networks. Next-Generation Wireless Systems (NGWS) integrate different wireless systems, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. In this paper, we propose to enhance the handoff performance of mobile IP in wireless IP networks by reducing the false handoff probability in the NGWS handoff management protocol. Based on the information of false handoff probability, we analyze its effect on mobile speed and handoff signaling delay.

A handoff management for Next Generation Wireless Systems

Next Generation Wireless Systems (NGWS) include co-existence of current wireless technologies such as WLANs, WiMAX, General Packet Radio Service (GPRS) and Universal Mobile Telecommunications System (UMTS). The important and challenging issue in NGWS is seamless handoff during the mobility of mobile node between different integrated networks. In this article, we propose a received signal strength measurement based handoff technique to improve handoff probability. By calculating the speed of MN (Mobile Node) and signaling delay information we try to take the right decision of handoff initiation time. Our theoretical analysis and simulation results show that by taking the proper decision for handoff we can effectively reduce false handoff initiation probability and unnecessary traffic load causing packet loss and call blocking.

Fast handoff implementation using distance measurements between mobile station and APs

The rapid growth in IEEE 802.11 based wireless LANs has led to new implementations like VoIP applications that require seamless handover. But handoff delays provide a serious barrier for such services to be made available to mobile platforms. Throughout the last few years there has been plenty of research aimed towards reducing the handoff delay incurred in the various levels of wireless communication. Here we propose new scanning method in which we determine the distance of nearest access points from the mobile node to bypass the main processes involved in increasing MAC layer handoff latency.

Fast handoff mechanism in WLANs based on neighbor graph information

According to IEEE 802.11 based WLAN standard, handoff at link layer (L2) consists of three distinct phases scanning, authentication and re-association. Scanning process takes 90% of the total handoff execution time [7] which is known as handoff delay or handoff latency. So in this paper our main goal is to reduce scanning delay, as a small handoff delay results a seamless and successful handoff. And a successful handoff ensures an uninterrupted flawless connectivity when the mobile station (STA) moves out of its old base stations (BS) coverage area. In this paper we proposed selective scanning based on position, speed and direction of motion of the Mobile station using the neighbor graph to reduce the scanning delay.

Reducing handoff call blocking probability by hybrid channel allocation

In cellular networks, handoff is the mechanism that transfers an on going call from the current cell to the next cell as the Mobile Unit (MU) moves through the coverage area of the cellular system. A handoff procedure results in a call termination in the current cell along with a call arrival in the destination cell. The Quality of Service (QoS) is improved when the handoff is performed successfully and as frequently as possible without being perceptible to the users. Thus, it is required to prioritize the handoff request so as to minimize the blocking probability of handoff calls. In this paper, we propose a hybrid channel allocation scheme which would effectively reduce the handoff call blocking probability. A handoff call queuing priority scheme has also been proposed to reduce forced call termination and hence enhance the performance of the system. Simulation results yield that the proposed mechanism outperforms the fixed channel assignment technique.

Minimization of Handoff Failure and Cellular Traffic by Introducing IEEE 802.11b WLAN Router in the Handoff Region

Handoff is an inherent drawback of mobile communication, especially in urban areas, due to the limited coverage of access points (APs) or base stations (BS). It is essential to minimize this delay to provide the user with seamless network coverage. Many people have applied efficient location management techniques in the literature of next generation wireless system (NGWS). However, seamless handoff management still remains an open matter of research. Here we propose to minimize the handoff failure probability by effectively placing a wireless local area network (WLAN) AP in the handoff region between two neighboring cells. The WLAN coverage, on one hand, provides an additional coverage in the low signal strength region, and on the other hand, relieves the congestion in the cellular network. Moreover, we perform the channel scanning within the WLAN coverage area, thus minimizing the handoff failure due to scanning delay.

Minimization of Handoff Latency by Area Comparison Method Using GPS Based Map

Handoff has become a drastic drawback in mobile communication system especially in urban areas owing to the limited coverage area of access points (AP). When a mobile node (MN) moves outside a range of its current access point it needs to perform a link layer handoff. This causes data loss and interruption in communication. In this paper we have proposed a process to minimize the handoff latency with the aid of GPS by minimizing the number of APs to be scanned by the MN during each handoff procedure. We have introduced a new algorithm based on the simplest concept of area. From GPS we can get an idea about the trajectory of motion of the MN and also the position of the neighbor APs. So taking these two factors into consideration we can reduce the scanning delay of the handoff to a great extent and thereby reducing the entire handoff latency.