Real-Time Communication in Packet-Switched Networks

Abstract The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have tra c characteristics and performance requirements that di er dramatically from those of current data-oriented applications, new communication network architectures and protocols will be required. In this paper we discuss the performance requirements and tra c characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research e orts can be considered

Real-time scheduling algorithms in wireless sensor networks

Wireless sensor networks have recently attracted research and industry interest. Wireless sensor networks have great potential to be used in many applications because of their unique characteristics. In many applications, such as military battlefield surveillance and medical health care, the data packets need to be delivered to their destinations with real-time constraints. Traditional real-time algorithms cannot be directly used in wireless sensor networks. Therefore, a new challenge in wireless sensor networks arises. In this thesis, we proposed several new real-time scheduling algorithms for wireless sensor networks. Unlike other existing real-time scheduling algorithms, we design real-time scheduling algorithms that not only consider the current situations of packets but also take the travelling history of packets into consideration. We evaluated these algorithms both in terms of the packet delivery rate and fairness to different flows. Finally we extended IEEE 802.11 to be able to prioritize the packets. We implemented these algorithms in NS-2 and extensively evaluated the experimental results. The results demonstrate that our new algorithms efficiently increase the system real-time performance and fairness