Designing and Analysis of A Wi-Fi Data Offloading Strategy Catering for the Preference of Mobile Users
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In recent years, offloading mobile traffic through Wi-Fi has emerged as a potential solution to lower down the communication cost for users moving in the urban area. Ideally, transmitting data only when the Wi-Fi is available can minimize the cost, which unfortunately will incur a large delay. In reality, users hope to reduce the cost, while keeping the delay in an acceptable range. Also, different users have different sensitivities to the cost and the delay performance. How to make a proper cost-delay tradeoff according to the user's preference is the key issue in the design of Wi-Fi offloading strategy.To address this issue, we propose a preference-oriented offloading strategy for current commercial terminals. In this strategy, the terminal transmits data via the cellular network if it loses the Wi-Fi and cannot connect to a new Wi-Fi hotspot before the deadline expires. We model this strategy as a three-state M/MMSP/1 queueing system, of which the service process is a Markov modulated service process (MMSP), and obtain the structured solutions by establishing a hybrid embedded Markov chain.Our analysis shows that, given the user's preference, there exists an optimal deadline to maximize the utility, which is defined as the linear combination of the cost and the delay. We also provide a method to select the optimal deadline. Our simulation demonstrates that this strategy with the optimal deadline can achieve a good performance.
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