关键词：
Broadcast on demand;Broadcast on schedule;Mobile real time read only transaction;Transaction processing;Updates dissemination;Bandwidth;Broadcasting;Data reduction;Data transfer;Network protocols;Real time systems;Mobile telecommunication systems
摘要：
Data management issues in mobile computing environments have got lots of concerns of relevant researchers. Among these research topics, data broadcast has been extensively investigated due to its advantages such as scalability and bandwidth effectiveness. While plenty of works have been done on this subject, it is still less touched when data broadcast is used to deliver frequently updated real-time data to read-only transactions with deadlines, which we call updates dissemination in this paper. Existing updates dissemination protocols are unsuitable for mobile real-time read-only transaction processing since they neglect the time constraints on both data and transactions. In this paper, we first identify the data dissemination requirements for read-only transaction processing in mobile real-time computing environments by formally defining several performance objectives. Then a novel updates dissemination protocol called hybrid forward multi-version data broadcast is proposed. In hybrid forward multi-version data broadcast, a set of new techniques including reducing the length of consistency intervals, instantly broadcasting updates policy and broadcast on-demand are incorporated seamlessly. Simulation results show that the proposed protocol can provide higher data currency and lower miss rate compared with existing updates dissemination protocols and is more appropriate for mobile real-time read-only transaction processing in broadcast disks.
