In this paper, we propose broadcast algorithms, based on the policies proposed in previous studies, to disseminate data items to time-constrained read-only transactions. In the proposed algorithms, the number of data items requested by a transaction will be considered explicitly in selecting the data items for broadcast. The purpose of the algorithms is to reduce the number of transactions missing their deadlines, and to minimize their mean response time. A detailed simulation model of a mobile computing system has been developed and extensive simulation experiments have been performed to study the performance characteristics of the proposed broadcast algorithms, and the results show that our broadcast algorithms outperform previously proposed algorithms.