INLyD: Inter-Network-Layer Delay as a Low-cost Quality Metric for Multi-hop Routing in Wireless Mobile Networks

The need for authentic and effective portrayal of the spatio-temporally changing quality of wireless links has gained wide attention especially over the last decade. Software-based link quality estimators (LQE) classify links with help of packet reception ratio (PRR), required number of packet transmissions (RNP) and scoring/grading schemes that again utilize PRR, RNP or retransmission based heuristics. On the contrary, this paper makes a case for inter-network-layer delay as a classification metric to boost end-to-end packet delivery in multi-hop communication. In essence our Inter-Network-Layer Delay metric (INLyD) uses a simplistic receiver-side in-band signaling scheme to passively accumulate queuing, retrying, back-off, transmission and propagation delay statistics while generating no additional control packet overhead. Our experiments show that the INLyD metric is not only light-weight (25% less MAC transmissions required per node) but substantially outperforms proactive broadcast based estimation schemes in static and mobile scenarios (1.7 and 1.2 times more end-to-end UDP delivery respectively for the performed experiments).