  Existing work that schedules concurrent transmissions collision-free suffers
from low channel utilization. We propose the Optimal Node Activation Multiple
Access (ONAMA) protocol to achieve maximal channel spatial reuse through a
distributed maximal independent set (DMIS) algorithm. To overcome DMIS's
excessive delay in finding a maximal independent set, we devise a novel
technique called pipelined precomputation that decouples DMIS from data
transmission. We implement ONAMA on resource-constrained TelosB motes using
TinyOS. Extensive measurements on two testbeds independently attest to ONAMA's
superb performance compared to existing work: improving concurrency,
throughput, and delay by a factor of 3.7, 3.0, and 5.3, respectively, while
still maintaining reliability.
