Earticle

Decisions for vertical handovers from WWAN to WMAN or WLAN access technologies are very challenging issue because it needs to deal with different radio access networks and make smart decisions for vertical handover calls between them. Especially the decisions for vertical handovers from WWAN to WLAN hotspots in heterogeneous mobile and wireless networks are very important because they impact the QoS of the mobile users, especially when they are using real-time services. In this paper we propose vertical handover decision algorithm from WWAN to WMAN or WLAN networks based on the load of the networks, speed of the mobile users, bandwidth and priority of the sessions of the mobile nodes. We use the IEEE 802.21 standard as a layout for implementing the algorithm. The results show that the proposed algorithm reduces unnecessary vertical handovers from WWAN to WMAN or WLAN access technologies and optimizes the load of the networks, improves the distribution of the call arrival rates and blocking probability of the vertical handovers from WWAN to WMAN or WLAN.

The vertical handover decision strategy in the heterogeneous wireless networks is very challenging issue because it needs to deal with many different radio access networks and make decisions for vertical handover calls between them. Due to traffic offloading the decisions for vertical handovers to WLAN hotspots in heterogeneous wireless networks are very important because they impact the QoS of the mobile users, especially when they are using real-time services. In this paper we propose vertical handover decision algorithm from WiMAX to WLAN networks based on the user’s speed and session’s priority (non-real-time or real-time service) of the mobile nodes. We use the IEEE 802.21 standard as a layout for implementing the algorithm. The implementation of our handover algorithm avoids unnecessary vertical handover from WiMAX to WLAN in scenarios with various traffic types and speeds of the mobile nodes. The results show that the proposed algorithm improves the vertical handover latency, packet loss and average throughput of the mobile users.

Next generation wireless systems consist of heterogeneous wireless networks. Wireless LAN (WLAN) and cellular mobile radio systems will be important part of heterogeneous networks. Universal mobile telecommunication system (UMTS) provides wide-area coverage, high mobility but relatively low data rate. WLAN is designed for low-range, high/medium data rate access, low mobility and can be used as a complement to larger cellular mobile radio systems. In this paper, we consider a simple heterogeneous system of WLAN and UMTS cell. Vertical handover plays a vital role in ensuring quality of service in heterogeneous networks. In this paper, we proposed a vertical handover algorithm for an integrated cellular/wireless LAN system. The design goal is to provide the user the best available quality of service (QoS) at any time. Moreover, connections are handed over independently between UMTS and WLAN, aiming at seamless service continuity. Here we have taken handover rate, probability of outage and probability of handover as the performance metrics. Simulation results show that adaptive vertical handover algorithm improves the performance.