Investigating Multiple Alternating Cooperative Broadcasts to Enhance Network Longevity

We propose a broadcast protocol that is based on a form of cooperative transmission called the Opportunistic Large Array (OLA). Multiple SNR (or transmission) thresholds are used to define mutually exclusive sets of OLAs, such that the union of the sets includes all the nodes in the network. The new protocol, termed Alternating OLA with Transmission Threshold (A-OLA-T), exercises a different set of OLAs on each consecutive broadcast from the same sink until all sets have transmitted once. Then the sequence repeats. Thus, broadcasts consume energy efficiently and uniformly over the network, and A-OLA-T is especially well suited for static networks. The transmission thresholds are optimized to maximize the network life if broadcasts were the only transmissions. In this paper, we first optimize triples of broadcasts, and then extend the optimization for a higher number of broadcasts.