Enrico Rantala

Modeling energy efficiency in wireless internet communication

For wireless mobile Internet users the length of the battery life is one of the most important performance factors. The energy efficiency of the data transmission over radio is a key component affecting the battery lifetime. This paper investigates WLAN energy consumption in network communication on a Mobile handset. We introduce an energy model that allows analysis and simulation of the energy efficiency of the Internet protocols on a Wireless Network Interface, and have extended the NS-2 simulation platform to allow investigating the energy consumption of the Radio Modem and the Power Amplifier in WLAN 802.11g network interface of a mobile device. We have also validated our model against measurements on real wireless hardware, and show that the simulation results closely match the real world behavior. We claim to present more detailed and accurate model of the WLAN energy consumption than what is done by the past work that allows designing and optimizing future Internet protocols towards more energy efficient behavior.

Throughput-fairness tradeoff evaluation for next-generation WLANs with adaptive clear channel assessment

In order to meet the exponential increase in wireless demand, new technologies are being considered for next-generation Wi-Fi systems (e.g., IEEE 802.11ax). Among these technologies is the adaptation of clear channel assessment (CCA) thresholds for high-efficiency (HE) stations (STAs) according to the beacons received signal strength indicator (RSSI). The motivation behind this approach is to enhance the network throughput by improving the spatial reuse (i.e., allowing simultaneous transmissions from nearby STAs). There exists an inherent tradeoff between increasing the network throughput, via adapting the CCA thresholds for HE STAs, and maintaining fairness between legacy and HE STAs. In this paper, we provide a theoretical framework to evaluate the aforementioned tradeoff. We also propose a centralized fairness mechanism (CFM), in which STAs switch between an adaptive phase (CCA adaptation is allowed) and a fixed phase (legacy and HE STAs use the same CCA threshold). We formulate an optimization problem with the objective of determining the optimal switching strategy that maximizes the network throughput while maintaining a lower bound on per-STA throughput. Finally, we validate the proposed mechanism using simulations.