Timeliness Evaluation of Intermittent Mobile Connectivity over Pub/Sub Systems

International audienceSystems deployed in mobile environments are typically characterized by intermittent connectivity and asynchronous sending/reception of data. To create effective mobile systems for such environments, it is essential to guarantee acceptable levels of timeliness between sending and receiving mobile users. In order to provide QoS guarantees in different application scenarios and contexts, it is necessary to model the system performance by incorporating the intermittent connectivity. Queueing Network Models (QNMs) offer a simple modeling environment, which can be used to represent various application scenarios, and provide accurate analytical solutions for performance metrics, such as system response time. In this paper, we provide an analytical solution regarding the end-to-end response time between users sending and receiving data by modeling the intermittent connectivity of mobile users with QNMs. We utilize the publish/subscribe (pub/sub) middleware as the underlying communication infrastructure for the mobile users. To represent the user's connections/disconnections, we model and solve analytically an ON/OFF queueing system by applying a mean value approach. Finally, we validate our model using simulations with real-world workload traces. The deviations between the performance results foreseen by the analytical model and the ones provided by the simulator are shown to be less than 5% for a variety of scenarios

Analytical Models of Short-Message Reliability in Mobile Wireless Networks

Applications like Twitter which use chat-like short messaging systems (SMS) have been widely used in public, political, military, emergency, humanitarian and other fields. Such applications usually involve servers (controllers) which control and forward messages from a sending client to a receiving client. The use of mobile wireless networks for such messaging systems has been increasing at a fast pace. To cope with this increase, there need to be efficient communication protocols and algorithms. To design such protocols and algorithms requires extensive analysis and understanding of the behavior of the communicating nodes under a given mobility scenario. One of the good metrics to understand the performance of such protocols is the reliability of message delivery. In this paper we present analytical models of the average reliability of short (chat-like) message delivery in mobile wireless networks as a multivariate function of the transmission range, movement area dimensions, number of servers (base stations) and message deadline (lifetime) under moderate realistic assumptions which can be easily relaxed and extended. Simulation results show that our analytical models give very good estimation of the average reliability of message delivery.unpublishednot peer reviewe