Data broadcast is widely deployed to realize bandwidth efficiency in a mobile computing environment. However, traditional data broadcasting assumes that mobile users can only retrieve one data item in each time slot. Therefore, the above constraint leads to access conflicts and requires the mobile users to wait until the next broadcast cycle to retrieve the requested information. In this paper, we propose a novel data broadcasting framework that adopts network coding with the stored data items in users. In our approach, a server encodes multiple data items in each time slot, while each mobile user is able to retrieve the data item by decoding the encoded data items with the locally stored data items. We propose an algorithm to generate the broadcast program to minimize the average access time. In addition, our algorithm can avoid coding redundant data in each time slot to reduce access delay. Our simulation results show that our algorithm can reduce the access time by 56% as compared to no coding scheme.
['Chung-Hua Chu', 'De-Nian Yang', 'Ming-Syan Chen']
Using Network Coding for Dependent Data Broadcasting in a Mobile Environment