WiHaul: max-min fair wireless backhauling over multi-hop millimetre-wave links

The mobile networking community is pursuing densification of small cell deployments to address the capacity crisis inherent to the projected exponential increase in mobile data traffic. Connecting massive numbers of access points to the Internet using optical fibre is however both very complex and expensive. In this paper we tackle small cell backhauling wirelessly, building upon recent advances in millimetre-wave technology. We propose a resource allocation algorithm for aggregate data flows traversing such multi-hop backhauls, and specify WiHaul, a light-weight hierarchical scheduling protocol that enforces the computed airtime shares and coordinates multi-hop transmissions effectively. To achieve high throughput performance while ensuring low demand flows are satisfied, we adopt a max-min fair allocation strategy. Results we present show our solution attains max-min fairness through a non-trivial partitioning of the airtime budget available in cliques of sub-flows, which depends on flow demands, their paths, and the capacities of the links traversed.