# A novel alternative to Cloud RAN for throughput densification: Coded pilots and fast user-packet scheduling at remote radio heads

## TL;DR

This paper proposes a new approach for wireless networks with remote radio heads, using coded pilots and fast user scheduling to significantly improve area spectral efficiency in dense deployments.

## Contribution

It introduces a decentralized, user-centric scheduling method with coded pilots and sector-based channel resolution, enhancing multiplexing gains over traditional spatial pilot reuse.

## Key findings

- Simulations show many-fold improvements in area multiplexing gains.
- Controlling user PPP intensity and pilot beam-width enhances performance.
- Method is effective in large-area, dense RRH deployments.

## Abstract

We consider wireless networks of remote radio heads (RRH) with large antenna-arrays, operated in TDD, with uplink (UL) training and channel-reciprocity based downlink (DL) transmission. To achieve large area spectral efficiencies, we advocate the use of methods that rely on rudimentary scheduling, decentralized operation at each RRH and user-centric DL transmission. A slotted system is assumed, whereby users are randomly scheduled (e.g., via shuffled round robin) in slots and across the limited pilot dimensions per slot. As a result, multiple users in the vicinity of an RRH can simultaneously transmit pilots on the same pilot dimension (and thus interfering with one another). Each RRH performs rudimentary processing of the pilot observations in "sectors". In a sector, the RRH is able to resolve a scheduled user's channel when that user is determined to be the only one among the scheduled users (on the same pilot dimension) with significant received power in the sector. Subsequently, only the subset of scheduled users whose channels are resolved in at least one sector can be served by the system. We consider a spatially consistent evaluation of the area multiplexing gains by means of a Poisson Point Process (PPP) problem formulation where RRHs, blockers, scatterers and scheduled user terminals are all PPPs with individual intensities. Also, we study directional training at the user terminals. Our simulations suggest that, by controlling the intensity of the scheduled user PPP and the user-pilot beam-width, many fold improvements can be expected in area multiplexing gains with respect to conventional spatial pilot reuse systems.