Link-to-System Mapping for ns-3 Wi-Fi OFDM Error Models

The ns-3 simulator contains detailed models of the Wi-Fi MAC layer, including beaconing, rate control, collision avoidance, block acknowledgments, and many other features. However, it relies on abstraction at the physical layer to scale well; Wi-Fi frames are evaluated by specialized interference trackers and analytical error models to arrive at frame reception decisions on a frame-by-frame basis, rather than symbol-by-symbol. Analytical models can provide fairly tight bounds for simple scenarios (additive white Gaussian noise (AWGN) channels with single antennas and limited interference), but the industry relies on detailed link-level sim-ulations to understand more complicated scenarios. This paper reports on an extensive campaign to conduct link simulations of Wi-Fi OFDM performance over AWGN and fading channels, using a commercial link simulator with Wi-Fi support, with results val-idated against published references. Next, we describe a specific implementation of a technique generally known as link-to-system-mapping, to allow a vector of per-subcarrier signal-to-noise ratios to be distilled into a single “effective SNR” value that can be used to determine performance using link simulation results of the AWGN channel. Finally, we report on the support of our link simulation results in a new ns-3 ErrorRateModel based on tables compiled from link simulation results. Our broader contributions are the link simulation programs themselves which allow others to reproduce and extend the basic tables that we provide, and flexibility in the ns-3 implementation to allow additional tables to be added over time.