A wired router can eliminate 802.11 unfairness, but it's hard

As mobile computing becomes ubiquitous and airspace more congested, it is increasingly important to fairly distribute bandwidth between competing wireless devices in order to ensure predictable and satisfactory performance for end users. In prior work, we have proposed a cross-layer approach called Shaper [3, 4] that uses TCP and a central router rather than the 802.11 protocol to decide the outcome of bandwidth allocation. The key idea is to avoid airspace congestion from happening in the first place. Shaper is effective and also easy to deploy. However, its implementation faces many fundamentally difficult challenges. This paper details these challenges and possible solutions.