A Cross-Layer User Centric Vertical Handover Decision Approach Based on MIH Local Triggers [chapter]

Maaz Rehan, Muhammad Yousaf, Amir Qayyum, Shahzad Malik
2009 IFIP Advances in Information and Communication Technology  
Vertical handover decision algorithm that is based on user preferences and coupled with Media Independent Handover (MIH) local triggers have not been explored much in the literature. We have developed a comprehensive crosslayer solution, called Vertical Handover Decision (VHOD) approach, which consists of three parts viz. mechanism for collecting and storing user preferences, Vertical Handover Decision (VHOD) algorithm and the MIH Function (MIHF). MIHF triggers the VHOD algorithm which operates
more » ... on user preferences to issue handover commands to mobility management protocol. VHOD algorithm is an MIH User and therefore needs to subscribe events and configure thresholds for receiving triggers from MIHF. In this regard, we have performed experiments in WLAN to suggest thresholds for Link Going Down trigger. We have also critically evaluated the handover decision process, proposed Justintime interface activation technique, compared our proposed approach with prominent user centric approaches and analyzed our approach from different aspects. commercial networks subscription details and user preferences regarding network selection are application layer features. While moving, whenever a Mobile Node (MN) is in overlapping region, effective network selection becomes a task that requires intelligent decision making based upon selected information from multiple layers and therefore it openly speaks off the necessity of a crosslayer design [5] . Users would like to avoid inappropriate handover decisions due to varying cost of different wireless access networks. The user may require from the system to choose either a cost effective network, or a best performance network even if it is costly because the connectivity is more important, or the user needs a dynamic hybrid approach which exhibits different behavior in different situations. 802 family of IEEE includes a variety of wireless technologies like 802.11, 802.15, 802.16 that help to establish Local, Personal and Metropolitan area networks respectively. Similarly, cellular networks like GPRS, EDGE, UMTS provide IP support and allow devices to be connected to Wide Area Network. This builds an overall picture in which networks with wide coverage encompass networks with small coverage thus creating overlapping regions and the need of handover. When a Mobile Node (MN) leaves its current network and enters into a new network, a Handover (HO) process is required so that the current endtoend services of MN may continue. Horizontal Handover (HHO) happens when MN moves into same network technology. Otherwise it is Vertical Handover (VHO). Link Layer (L2) notifications help to speed up the process of HO. Abstract or Unified L2 notifications [19, 21, 22, 24] facilitate upper layers to receive these notification in an implementation/link technology independent way. Some of these abstractions have been specifically designed for L3 handover [21, 22] , while others are for L3 & above in general [19, 24] . Testbed implementations [21, 23] are also available that use Link Up and Link Down triggers to facilitate L2/L3 handover. Our crosslayer solution focuses on handover decision making in a user centric way that intelligently selects a target network among the candidates. After HO decision phase, any mobility management protocol (e.g. MIPv6, EMF, TCP migrates etc.) can be used for handover. Media Independent Handover (MIH) [19] is a proposed framework of IEEE 802.21 WG which provides a generic interface between 'L3 & above' and 'L2 & below' for different network technologies, e.g. 802 family, 3GPP and 3GPP2. MIH divides the handover into Initiation, Preparation and Execution phases [17]. Handover execution is the phase in which mobility management protocols execute and MIH has nothing to do with it. Handover Initiation and Preparation are the phases where MIH is involved. Handover is initiated when observed link layer parameter, e.g. RSS, missed beacons, packet error rate, etc. degrade enough to indicate either a connection breakage or network load. As a result, handover preparation phase starts in which information about the neighboring networks is accumulated through the already active interface with the help of Point of Service (PoS) entity of current network, as proposed by MIH. MIH provides the aforementioned services to the MIH User through MIH_SAP and
doi:10.1007/978-3-642-03841-9_32 fatcat:yqsv5jmo65efbimr65eo3j3k2y