International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.3, No.4, August 2012 DOI : 10.5121/ijasuc.2012.3403 21       Manoj Sharma 1 , Dr. R.K.Khola 2 1 Research Scholar, Faculty of Engineering & Technology, MDU Rohtak, Haryana, India neelmanoj@gmail.com 2 Professor & Head, PDM College of Engineering, Bahadurgarh, Haryana, India ABSTRACT With the development of wireless communication technology, various wireless networks have been deployed. Heterogeneous networks will be dominant in the next generation wireless networks. In such networks, providing a seamless handoff by selecting the appropriate network is one of the key issues. In order to be always best connected for various applications, the network selection procedure, in heterogeneous multi-access environment during vertical handover decision is intended to choose the most suitable network for mobile user. In this paper, a handoff decision scheme is proposed that will help to choose the correct network and fuzzy logic is applied to deal with the imprecise information of some criteria and user preference. KEYWORDS Fuzzy Logic, Handoff Decision, Heterogeneous Wireless Environment, Mobile Node. 1. INTRODUCTION Next generation wireless network is a network of emerging various networks such as CDMA2000, Wireless LAN and WCDMA into all IP-based networks that will make it globally available. This technology is a very complex technology of integrating different new techniques, and services for a higher speed wireless internet access. The main concern of the next- generation wireless networks is the integration of heterogeneous wireless technologies. This integration invokes some challenges, such as handover decision making and mobility management. Provisioning of seamless handover is one of the key topics in next generation wireless networks. Vertical handover decisions evaluate candidate NAPs based on different standards. Making a suitable handover decision according to different standard based parameters of access points in heterogeneous wireless networks is providing a scope of research. Wireless network technologies are different from each other usually in terms of bandwidths, frequencies, latencies, and etc. Currently, no single technology simultaneously provides a low latency, high bandwidth, and cost-effective services to all mobile users. So as to enable seamless communications in wireless environment, providing support for well-organized handoff between the various technologies will play a crucial role. Handoff is described as a process of transferring an ongoing call or data session from one access point to another in wireless networks. It can also be defined as the process of changing the communication channel (frequency, modulation scheme, data rate, spreading code, or combination of them) associated with the current connection while a call is in progress. Traditional handoff process, called horizontal handoff, takes place to provide a seamless service when a user moves between two adjacent cells. Generally, horizontal handoff is based on only single parameter such as RSS (Received Signal Strength), SNR (Signal-to- Noise Ratio), etc.,