Implementation of backpressure-based routing integrated with Max-Weight Scheduling in a wireless multi-hop network

Reliable transmission is one of the key objectives of research on wireless network optimization. The backpressure-based Max-Weight Scheduling (MWS) policy is theoretically proven to be the optimal solution for achieving the highest available throughput. On the other hand, proactive routing protocols, such as Optimized Link State Protocol (OLSR), are able to compute reliable paths, which, in turn, can be used as a basis for MWS-based resource allocation. However, in its standard implementation, OLSR is a single-path protocol, whereas it is known that at least in some scenarios MWS algorithms can provide better network performance when used together with multi-path packet forwarding. Following this motivation, we implemented a modification of the OLSR protocol aimed at realizing multi-path routing in cooperation with the backpressure policy. The scheduling component was implemented at the application layer, and was supported by a mechanism for an indirect estimation of the MAC-layer queue state. Thanks to this approach, the system may work with the unmodified existing 802.11 MAC, and can be deployed in existing wireless networks. We tested the proposed solutions in a realistic wireless network scenario.