Model Based Approaches for Bandwidth Estimation
The research community has devoted a lot of effort to design novel bandwidth estimation tools during the last decade. However the existing methodologies and tools have been designed for wired environments. When considering WLAN environments, various preliminary studies have shown that the application of results obtained in wired setups is not straightforward. In this case, the contention for medium sharing among multiple users inherent to CSMA/CA access schemes has remarkable consequences on the behavior of and results obtained by bandwidth measurement techniques. Within the framework of a joint program between UPC (Universitat Politècnica de Catalunya) and CTTC (Centre Tecnològic de Telecomunicacions de Catalunya) we have analyzed theoretically the particularities of bandwidth inference in wireless scenarios. Our analysis reveals that the distribution of access delay shows a transient regime before reaching a stationary state. And it also shows how dispersion-based measurements that use a short number of probing packets are biased measurements of the achievable throughput, the origin of this bias lying on the transient detected in the access delay of probing packets. Overall, the analysis have several consequences that are expected to influence the design of bandwidth measurement tools as well as to better understand the results obtained with them in CSMA/CA links. You can find more information at:
- Marc Portoles, Albert Cabellos, Josep Mangues, Albert Bnchs, Jordi Domingo-Pascual “Impact of Transient CSMA/CA access delays on Active Bandwidth Measurements” in Proc. of ACM/SIG Internet Measurement Conference (IMC) 2009