Mixed-Numerology Signals Transmission and Interference Cancellation for Radio Access Network Slicing

Abstract

A clear understanding of mixed-numerology signals multiplexing and isolation in the physical layer is of importance to enable spectrum efficient radio access network (RAN) slicing, where the available access resource is divided into slices to cater to services/users with optimal individual design. In this paper, a RAN slicing framework is proposed and systematically analyzed from the physical layer perspective. According to the baseband and radio frequency (RF) configurations imparities among slices, we categorize four scenarios and elaborate on the numerology relationships of slices configurations. By considering the most generic scenario, system models are established for both uplink and downlink transmissions. Besides, a low out of band emission (OoBE) waveform is implemented in the system for the sake of signal isolation and inter-service/slice-band-interference (ISBI) mitigation. We propose two theorems as the basis of algorithms design in the established system, which generalize the original circular convolution property of discrete Fourier transform (DFT). Moreover, ISBI cancellation algorithms are proposed based on a collaboration detection scheme, where joint slices signal models are implemented. The framework proposed in the paper establishes a foundation to underpin extremely diverse use cases in 5G that implement on a common infrastructure.

Interference Analysis in Multi-Numerology OFDM Systems: A Continuous-Time Approach

“…T (2) ∆f (1) = 30kHz ∆f (2) = 15kHz In 5G new radio (NR) specifications, OFDM with mixed numerologies is considered to enable multi-service communications over a unified physical layer [6]. One viable solution is to multiplex mixed numerologies in the frequency domain, i.e., the system bandwidth is divided into several bandwidth parts (BWPs), each having a distinct numerology optimized for a particular service.…”

“…To purely study the effect of interference from one numerology to another, without loss of generality, in our system model, we consider two differing numerologies 2 , namely, numerology 1 and numerology 2. The subcarrier spacing ∆f (i) and symbol duration T (i) associated with different numerologies i, i = {1, 2}, are related to one another via a scaling factor ν, where ∆f (1) ∆f (2) =…”

“…Assuming ∆f (1) > ∆f (2) with the scaling factor being greater than 1, and based on 5G NR specifications [6], ν is only chosen as powers of two, ν = 2 µ , µ ∈ {1, 2, • • • }. Fig.…”

“…Fig. 1 represents the time-frequency relation with two numerologies for ν = 2 where ∆f (1) = 2∆f (2) and ∆T (1) = 0.5∆T (2) . As it is shown in this figure, each symbol associated with numerology 2 overlaps with two symbols associated with numerology 1 in the time domain.…”

“…Each of these services has distinct quality of service (QoS) requirements, such as throughput, latency, reliability, and number of connected users to be served simultaneously. This calls for a high degree of flexibility in designing waveform parameters [2]. Conventional resource distribution adopts a single numerology 1 with uniform frame design to provide different services, as in 4G long term evolution (LTE).…”