- 11:30 Experimental Design and Analysis of Transmission Properties in an Indoor Wireless Sensor Network
Dennis Christmann (University of Kaiserslautern, Germany); Ivan Martinovic (University of Oxford, United Kingdom (Great Britain))
In this paper, we systematically investigate different factors and their effects on the wireless transmission properties using a full-factorial experimental design of a real-word wireless sensor network. We quantify the impact of primary factors such as the wireless channel, physical position, transmission power, line-of-sight, and their interactions on the wireless communication. While some of our results support conventional assumptions, this study also shows that there are many properties which are in contrast to existing findings. For example, there is no significant correlation in the measured received signal strength between different but equally-distant transmitters, yet the correlation coefficient between two transmitters is above 0.95. Further analysis reveals the strong interaction of transmission frequency and the physical position, while the transmission power and the direction of the transmissions have an isolated, non-interacting effect on the measured received signal strength. Since the analyzed network consists only of a simple, low-cost hardware, the results of this experimental analysis can serve as valuable insights in planning and deploying wireless sensor networks in different application scenarios.
- 11:50 Field Measurements of 802.11 Collision, Noise and Hidden-Node Loss Rates
Douglas Leith (Trinity College Dublin, Ireland); David Malone (Maynooth University, Ireland)
In this paper we present the first field measurements taken using a new approach proposed in [1] for mea- suring link impairments in 802.11 WLANs. This uses a sender-side MAC/PHY cross-layer technique that can be implemented on standard hardware and is able to explicitly classify lost transmission opportunities into noise-related losses, collision induced losses, hidden- node losses and to distinguish among these different types of impairments on a per-link basis. We show that potential benefits arising from the availability of accurate and reliable data are considerable.
- 12:10 Practical design constraints for measuring utilization in hybrid paths using delay measurements
José Núñez-Martínez (Telefonica, Spain); Marc Portoles-Comeras (Cisco Systems Inc, USA); Albert Cabellos-Aparicio (Universitat Politècnica de Catalunya, Spain); Josep Mangues-Bafalluy (Centre Tecnològic de Telecomunicacions de Catalunya (CTTC), Spain); Jordi Domingo-Pascual (Universitat Politècnica de Catalunya - BarcelonaTech (UPC) & Technical University of Catalunya (UPC) Advanced Broadband Communications Center, Spain)
Recent research results have shown how measurements of bandwidth metrics using traditional tools and techniques have to be reconsidered in the presence of WLAN links. The main reason behind this is the CSMA/CA protocol used to regulate the distributed access in the wireless medium. In this paper we identify a set of practical issues that tools based on delay measurements must face to implement end-to-end bandwidth metrics in hybrid paths (i.e., wired/wireless). The paper provides results through extensive simulation to validate the findings of the study.