HARQ-aware allocation of computing resources in C-RAN

Francesca Bassi (1) , Hatem Ibn-Khedher (2)

1 IRT SystemX
2 LIPADE (URP_2517) - Laboratoire d'Informatique Paris Descartes

The principal tenet of C-RAN is the softwarization of the base-band signal processing, which enables the sharing of computing resources among ultiple radio heads. When the aggregate demand exceeds the processing capacity, a fraction of the radio packets is lost at PHY layer. Traditional computing resource allocation policies aim to minimize the packet loss rate. Dropping a PHY packet triggers a retransmission, unless the lost packet corresponds to the last available HARQ round, in which case the entirety of the radio resources spent on the multiple transmissions go to waste. This suggests that allocating computing resource accounting also for the HARQ transmission history may make a more efficient use of the bandwidth. We consider a simplified LTE uplink setting, and we measure the performance at the lower MAC layer (accuracy, goodput and average delay). We first compare the PHY-layer loss rate minimization and the cross-layer approaches using an ILP formulation. The cross-layer approach brings a tangible improvement, especially in accuracy. This suggests, for future work, that joint radio and computing resource allocation may further enhance spectral efficiency. We finally propose a probabilistic algorithm amenable to real-time operation which allows to mix strategies via parameter tuning, and we use it to explore the region of achievable goodput/accuracy trade-offs.

Domaines: Informatique [cs]

Francesca Bassi, Hatem Ibn-Khedher. HARQ-aware allocation of computing resources in C-RAN. IEEE ISCC 2020 (IEEE Symposium on Computers and Communications 2020), Jul 2020, Rennes, France. ⟨hal-02937797⟩