Sain Saginbekov

Frame aggregation is central to modern IEEE 802.11 networks, yet the existing performance models fail to capture how it behaves under usual unsaturated traffic. Some rely on a predefined service-time distribution; others cover only narrow unsaturated cases, such as stations withholding transmission until K packets accumulate or stations being modeled as if they always have a packet queued. This paper develops a performance model for 802.11 networks with frame aggregation under unsaturated traffic in which the aggregation size and service time emerge dynamically from the offered traffic load, the random backoff process, and the number of stations rather than from any of these simplifying assumptions. Beyond throughput, the model derives closed-form estimates of the average aggregation size, service time, and per-station queue length directly from the steady-state distribution of a three-dimensional Markov chain. Performance evaluations across two physical-layer rates (867 and 150 Mbps), two queue capacities, and different numbers of stations show that the proposed model produces throughput and aggregation-size estimates that closely match an event-driven simulator, while the service time and queue-length estimates reflect the model’s own assumption.

In Wireless Sensor Network (WSN) applications, such as monitoring valuable assets, the locations of assets should be kept private to hide the assets from adversaries. Much of the work that solves this problem, called Source Location Privacy (SLP) problem, has focused on networks where only a single source reports to the sink at a time. Therefore, existing solutions for the SLP problem may not show the same performance in networks where multiple sources report simultaneously. In this paper, we present a routing algorithm called Red paths to solve the SLP problem for WSNs with multiple sources. We perform simulation experiments and show that Red paths offer better location privacy, with a low message overhead, not only in networks with a single source but also in networks with multiple sources.

Software development for Wireless Sensor Networks (WSNs) is challenging due to characteristics of sensor nodes and the environment they are deployed in. Testing software in a real WSN testbed allows users to get reliable test results. However, real testbeds become more expensive as the number of sensor nodes in the network grows. Simulation tools are alternatives to real testbeds. They are cheaper, faster and repeatable. However, simulation results are not reliable as that of testbeds. Therefore, there is a need for a testing tool that can leverage the advantages of testbeds and simulation tools. These tools are usually called hybrid simulators. In this survey, we discuss several hybrid simulators that use real sensor motes integrated with a simulator to make software development cheaper, repeatable and to make the results more reliable.