On Determining Bandwidth Usage Threshold to Support Real-Time Multimedia Applications in Wireless Multimedia Sensor Networks

Real-time multimedia applications require Quality of Service (QoS) provisioning in terms of bounds on delay and packet loss along with soft bandwidth guarantees. The shared nature of the available bandwidth in Wireless Multimedia Sensor Networks (WMSNs) causes interference. Interference combined with the overheads associated with a Medium Access Control (MAC) protocol limit the available bandwidth in WMSNs. These overheads can result in congestion, even if transmission rates of nodes are well below the maximum bandwidth supported by an underlying communication technology. Congestion degrades the performance of admitted real-time multimedia flow(s). Therefore, in this paper, we experimentally derive the IEEE 802.15.4 channel capacity using an unslotted Carrier Sense Multiple Access Collision Avoidance (CSMA-CA) MAC protocol. Considering the experimental channel capacity estimation results, and the characteristics of real-time multimedia flows, we determine the threshold on bandwidth usage, so that the QoS requirements of real-time multimedia flows in terms of delay, bandwidth, and packet loss rate can be met. We performed several simulations, and results show that QoS requirements of applications are met operating within the bandwidth usage threshold determined in this paper. Simulation-based results further show that marginally exceeding the determined threshold value results in the performance degradation of at least one real-time multimedia flow.