Heterogeneous Non-Orthogonal Multiple Access for Ultra-Reliable and Broadband Services in Multi-Cell Fog-RAN
In this paper, a Fog-Radio Access Network (F-RAN) architecture is considered in which Ultra-Reliable and Low-Latency communications (URLLC) traffic is served by the Edge Nodes (ENs) of a cellular network, while enhanced Mobile BroadBand (eMBB) communications are handled centrally at a cloud processor as in a Cloud-RAN system. This solution guarantees the low-latency requirements of the URLLC service by means of edge processing, e.g., for vehicle-to-cellular use cases, as well as the high spectral efficiency for eMBB traffic via centralized baseband processing. In addition to the conventional orthogonal multiplexing of the two services, this work evaluates the performance of Heterogeneous Non-Orthogonal Multiple Access (H-NOMA), which enables eMBB and URLLC data, to share the same radio resources. Both uplink and downlink are analyzed by considering practical aspects such as fading, lack of channel state information for URLLC transmitters, rate adaptation for eMBB transmitters, finite fronthaul capacity, and different coexistence strategies, such as puncturing.
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