On the Performance of Multi-Radio ARQ and Packet Scheduling in Ambient Networks

In alignment to an "always best experience" scenario, we assess gains on user traffic in the context of a multi-radio access environment where heterogeneous radio technologies are integrated at link layer and users are jointly scheduled across multiple radio accesses (RAs). Such integration allows for an implementation of multi-radio transmission diversity (MRTD) which switches transmission of a user's data over the available RAs. The RA selection is based on measurements of radio link quality as reported by the radio interface. The application of an ARQ scheme utilising multiple RAs (MR-ARQ) in conjunction with MRTD provides added gains on user delay and neutralizes parts of degradations in spectral efficiency caused by reporting delays. Such multi-radio ARQ mechanism exploits the diversity across independent RAs, and results in gains in throughput over those achieved by RA-specific ARQ. MRTD when combined with MR-ARQ shows gains of up to 35% in spectral efficiency compared to the case where the radio accesses operate independently.