Robust STDMA Scheduling in Multi-hop Wireless Networks for single-node position perturbations

A major design issue in Multi-hop Wireless Networks is the Medium Access Control (MAC) protocols that determine how nodes share the channel to transmit their packets. One type of MAC protocol with efficient spatial reuse characteristics are the Spatial TDMA (STDMA) protocols. STDMA protocols are a class of conflict-free MAC protocols that enable high spectral utilization by scheduling transmissions on the channel. Its main features are high throughput and the possibility of providing delay guarantees. We studied the sensibility of STDMA networks to disruption caused by slow mobility of one "critical" node (single-user perturbation), that causes problems to the schedule maintenance. We assessed a framework that produces robust STDMA scheduling against these topological changes. To do that, we introduced and analyzed heuristic algorithms that mainly exploit capabilities of the physical layer such as power and rate control, and rerouting. We considered the limited-mobility management in STDMA networks to find the ranges where our heuristics will avoid re-scheduling of the whole STDMA frame. We found that a substantial throughput degradation due to slow mobility in STDMA networks can be compensated by means of power or rate control, and rerouting. Our results showed that rate-controlled (RC) STDMA is the most promising scheme to maintain communication under slow mobility.