Cooperative tag communications

In this paper we propose the use of multiple tags cooperatively backscattering the same message to improve reverse-link range of passive communications. Since no control of relative backscatter phase is available, backscattered amplitude is approximately Rayleigh-distributed in a line-of-sight environment. Selection of optimized subsets is projected to provide diversity gain, particularly in a fading environment. Preliminary experimental data demonstrates the expected increase in backscattered amplitude from multiple tags. We propose an approach for extending the 18000-6C protocol to support cooperative tags query operations and subset selection.