| Summary: | 碩士 === 南華大學 === 資訊管理學系碩士班 === 98 === On-demand broadcast is an effective wireless data dissemination technique in data broadcast environment. In real world, users'' queries usually include multiple data items. Recently, there are many related papers began to explore multi-item queries of data scheduling. However, traditional on-demand data broadcast scheduling assume that each time slot includes only one data item. Therefore, the above constraint demands a mobile user to wait until the next broadcast cycle to retrieve the data item if he misses the item in the cycle. Using network coding technique, server can encode and broadcast multiple data items in a time slot. The data item was repeated allocated different positions in the broadcast cycle. A user can retrieve data items which they needed on the places in a broadcast cycle by using the user''s cached data items to decode it. In this paper, we based on network coding model and we propose a new weight metrics that decided which query should be service with the highest priority. The metrics considers the factor of requests deadline to reduce deadline miss rate. Experiment results show that our algorithm can increase 20% success rate (which only increase 5% user''s access time) compared with [3].
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