Networking and Communication Engineering

Debabrata Sarddar ¹, Shubhajeet Chatterjee ², Arnab Raha ³, Karmajyoti Panigrahi ⁴, Pulak Mazumder ⁵, Utpal Biswas ⁶, M. K. Naskar ⁷

Affiliations
1 Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata – 700032, IN
2 Department of Electronics and Communication Engineering, Institute of Engineering. & Managment College, Saltlake, Kolkata-700091, IN
3 Jadavpur University at the Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata–700032, IN
4 Techno India College of Technology at the Department of EIE, IN
5 Department of Electronics and Telecommunication Engineering, Regent Education & Research Foundation, Barracpore, IN
6 Kalyani University at the Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata – 700032, IN
7 Jadavpur University at the Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata – 700032, IN

Abstract

Due to rapid growth in IEEE 802.11 based Wireless Local Area Networks (WLAN), handoff has become a burning issue. A mobile node (MS) requires handoff when it travels out of the coverage area of its current access point (AP) and tries to associate with another AP. 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. In this article we propose to minimize the handoff latency by minimizing the number of APs scanned by the mobile station (MS) during each handoff procedure. We assume hexagonal coverage area of an AP with the AP situated at the center. By GPS, we can note down the co-ordinates of the MS at any instant. Segmenting the hexagon into 6 segments with 600 coverage area for each, we determine the trajectory of the MS by GPS. Hence the direction of motion of the MS can be determined, which in turns gives the AP towards which the MS is heading towards. This reduces the number of APs to be scanned. Thus, on an overall basis, the handoff latency can be reduced by almost half to one third of its value.

Keywords

IEEE 802.11, Handoff Failure, GPS (Global Positioning System), Channel Allocation, Neighbor APs.

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Debabrata Sarddar ¹, Shubhajeet Chatterjee ², Ramesh Jana ³, Mandovi Mukherjee ³, Sreya Mallik ³, Utpal Biswas ⁴, M. K. Naskar ³

Affiliations
1 Jadavpur University, Department of Electronics & Telecommunication Engineering, IN
2 Institute of Engineering & Management, Department of Electronics & Telecommunication, IN
3 jadavpur University, Department of Electronics & Telecommunication, IN
4 Jadavpur University, Department of Electronics & Telecommunication, IN
5 Kalyani University, Department of Electronics & Telecommunication, IN

Abstract

Presently IEEE 802.11b based wireless networks are being widely used in various fields like personal as well as business applications. Handoff is a critical issue in IEEE 802.11b based wireless networks. When a mobile node (MN) moves away from the range of its current access point (AP) it needs to perform a link layer handoff. This causes data loss and interruption in communication. According to IEEE 802.11b link layer2 (L2) handoff consists of three phases – scanning, authentication and re-association. Scanning process delay is 90% of the total handoff delay. So in this paper we propose a better scanning mechanism to reduce handoff latency. Using GPS we determine the direction of velocity of the MN as well as position. It reduces the time to find the closest and best AP among all neighbor APs. This process effectively reduces the handoff latency.

Keywords

IEEE 802.11b, Handoff Latency, GPS (Global Positioning System), Direction of Velocity of MN, Neighbor APs, Mobile Node (MN).

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