In this letter, we propose a channel-aware scheduling algorithm to support real-time applications in wireless multimedia sensor networks. Multimedia streams are sensitive to real-time delivery but can tolerate some packet loss. Therefore, this specific application is modelled as an (m,k)-firm stream. To satisfy the real-time requirements, a scheduling scheme that provides packet partitioning and real-time delivery is proposed. Packet partitioning combines static assignment and dynamic adjustment while considering the channel state. The scheme is designed to minimize the number of mandatory packets delivered in a bad channel state to avoid dynamic failure. In addition, automatic repeat request technology is introduced to enhance the reliability of real-time delivery. Simulations and analyses show that the proposed scheme has a good ability to withstand a bad channel status.

In this letter, we propose a revised geographic routing protocol and a scheduling algorithm to support real-time applications, which are often observed in wireless sensor networks. In order to meet real-time requirement, a specific application is modeled as an (m,k)-firm stream that has a property of weakly hard real-time system. In addition, both a priority-based scheduling and a geographic forwarding scheme based on delay, distance, and remaining slack time are newly proposed. Simulations and their analysis are followed to validate the suitability of reduced dynamic failure probability and extended network lifetime.