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Issue No. 04 - April (2014 vol. 13)
ISSN: 1536-1233
pp: 752-765
Zaixin Lu , Dept. of Comput. Sci., Univ. of Texas at Dallas, Richardson, TX, USA
Yan Shi , CSSE Dept., Univ. of Wisconsin-Platteville, Platteville, WI, USA
Weili Wu , Dept. of Comput. Sci., Univ. of Texas at Dallas, Richardson, TX, USA
Bin Fu , Dept. of Comput. Sci., Univ. of Texas-Pan American, Edinburg, TX, USA
Wireless data broadcast is a popular data dissemination method in mobile computing environments because of its capability of concurrently disseminating data to multiple users. In this paper, we study the data retrieval scheduling problem for multi-item requests in multi-channel broadcast environments. To maximize the number of downloads given a deadline, we define a problem called largest number data retrieval (LNDR). We prove the decision problem of LNDR is NP-hard, and we investigate approximation algorithm for it. We also define another problem called minimum cost data retrieval (MCDR), which aims at downloading a set of requested data items with the least response time and energy consumption. We prove MCDR is NP-hard to approximate to within any non-trivial factor. Therefore, we investigate heuristic algorithm for it. Finally we provide simulation results to demonstrate the practical efficiency of the proposed algorithms.
Schedules, Time factors, Switches, Energy consumption, Scheduling, Indexes, Servers

Zaixin Lu, Yan Shi, Weili Wu and Bin Fu, "Data Retrieval Scheduling for Multi-Item Requests in Multi-Channel Wireless Broadcast Environments," in IEEE Transactions on Mobile Computing, vol. 13, no. 4, pp. 752-765, 2014.
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