Efficient Coding-Based Scheduling for Multi-Item Requests in Real-Time On-Demand Data Dissemination

On-demand broadcast is an effective data dissemination technique to enhance the system ability to handle dynamic client access patterns. With the development of real-time wireless applications, it is practical for clients to request multiple related data items with time constraint in one request. For real-time data broadcast, items are only useful if they can be received by clients before expiration; otherwise, the related requests become invalid. Hence, minimizing the number of requests that miss their deadlines becomes an important task in on-demand broadcast, especially for multi-item scenario, where more requests are inclined to miss their deadlines due to the heavier workload and greater complexity, compared with single-item scenario. In this paper, we propose a network coding-based scheduling algorithm for real-time multi-item data dissemination. The proposed algorithm exploits the coding opportunities between cached and requested data items and integrates network coding with data scheduling to minimize the deadline miss ratio. Extensive simulation results demonstrate that the proposed algorithm achieves the lowest deadline miss ratio under various circumstances. In addition, the high efficiency of the proposed algorithm in utilizing the transmission bandwidth is proved for that fewer instances of ineffective service are provided for satisfying clients’ requests within time constraints