The possibility of a single user making repeated request submission attempts (referred to as the retrieval phenomenon), as identified and studied in the literature on unicast wireless systems, has been largely overlooked by previous research works on wireless data broadcast (WDB). The objective of this paper is to extend the analysis of the user retrieval phenomenon to wireless systems that, in addition to unicast service, also support a data broadcast service. Toward this goal, the paper provides a mathematical framework based on several performance measures appropriate for the analysis of hybrid unicast-broadcast systems in the presence of users’ retrievals. The robustness of the provided framework is validated through simulation.

The paper has a clear structure, with well-organized material, an excellent use of language, a length suitable for its purposes, and the appropriate number and quality of references. It sets up its subject very well, and creates a progressively ongoing interest. In both the analytical and simulation facets of its topic, the paper presents the appropriate level of detail, without overly burdening potential readers. An easy understanding of the paper requires a basic background in queueing systems. The paper concludes with a discussion of important future research challenges, for those dealing with hybrid WDB systems.