Implementing a Software-based 802.11 MAC on a Customized Platform

Wireless network (WLAN) platforms today are based on complex and inflexible hardware solutions to meet performance and deadline constraints for Media Access Control (MAC). Contrary to that, physical layer solutions, such as Software Defined Radio, become more and more flexible and support several competing standards. A flexible MAC counterpart is needed for system solutions that can keep up with the rising variety of WLAN protocols. We revisit the case for programmable MAC implementations looking at recent WLAN standards and show the feasibility of a software-based MAC. Our exploration uses IEEE 802.11a-e as design driver, which makes great demands on Quality-of-Service, security, and throughput. We apply our SystemC framework for efficiently assessing the quality of design points and reveal trade-offs between memory requirements, core performance, application-specific optimizations, and responsiveness of MAC implementations. In the end, two embedded cores at moderate speed (< 200MHz) with lightweight support for message passing using small buffers are sufficient for sustaining worst-case scenarios in software.