Abstract-The next generation wireless networks will support the vertical handoff mechanism in which users can maintain the connections when they switch from one network to another (e.g., from IEEE 802.11b to CDMA 1xRTT network, and vice versa). Although various vertical handoff decision algorithms have been proposed in the literature recently, there is a lack of performance comparisons between different schemes. In this paper, we compare the performance between four vertical handoff decision algorithms, namely, MEW (Multiplicative Exponent Weighting), SAW (Simple Additive Weighting), TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), and GRA (Grey Relational Analysis). All four algorithms allow different attributes (e.g., bandwidth, delay, packet loss rate, cost) to be included for vertical handoff decision. Results show that MEW, SAW, and TOPSIS provide similar performance to all four traffic classes. GRA provides a slightly higher bandwidth and lower delay for interactive and background traffic classes.

Abstract-One of the major design issues in heterogeneous wireless networks is the support of vertical handoff. Vertical handoff occurs when a mobile terminal switches from one network to another (e.g., from WLAN to CDMA 1xRTT). The objective of this paper is to determine the conditions under which vertical handoff should be performed. The problem is formulated as a Markov decision process. A link reward function and a signaling cost function are introduced to capture the tradeoff between the network resources utilized by the connection and the signaling and processing load incurred on the network. A stationary deterministic policy is obtained when the connection termination time is geometrically distributed. Numerical results show good performance of our proposed scheme over two other vertical handoff decision algorithms, namely: SAW (Simple Additive Weighting) and GRA (Grey Relational Analysis).

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Abstract-One of the major design issues in heterogeneous wireless networks is the support of vertical handoff. Vertical handoff occurs when a mobile terminal switches from one network to another (e.g., from WLAN to CDMA 1xRTT). The objective of this paper is to determine the conditions under which vertical handoff should be performed. The problem is formulated as a Markov decision process. A link reward function and a signaling cost function are introduced to capture the tradeoff between the network resources utilized by the connection and the signaling and processing load incurred on the network. A stationary deterministic policy is obtained when the connection termination time is geometrically distributed. Numerical results show good performance of our proposed scheme over two other vertical handoff decision algorithms, namely: SAW (Simple Additive Weighting) and GRA (Grey Relational Analysis).

Abstract-The 4th Generation (4G) wireless communication systems aim to provide users with the convenience of seamless roaming among heterogeneous wireless access networks. To achieve this goal, the support of vertical handoff in mobility management is crucial. This paper focuses on the vertical handoff decision algorithm, which determines under what criteria vertical handoff should be performed. The vertical handoff decision problem is formulated as a constrained Markov decision process (CMDP). The objective is to maximize the expected total reward of a connection subject to the expected total access cost constraint. In our model, a benefit function is used to assess the quality of the connection, and a penalty function is used to model signaling and call dropping. The user's velocity and location information are considered when making the handoff decisions. The value iteration and Q-learning algorithms are used to determine the optimal policy. Numerical results show that our proposed vertical handoff decision algorithm outperforms another scheme which does not consider the user's velocity.