Premises Radio Access Station

Description

The Premises Radio Access Station (PRAS) is a network element introduced in 3GPP Release 18, falling under the broader category of Customer-Premises Equipment (CPE) for 5G systems. It is essentially a 5G NR radio access node deployed at a customer's premises, such as within a factory, office building, university campus, or hospital. The PRAS provides the radio interface (Uu) to standard 5G User Equipment (UEs) within its coverage area, creating a localized 5G cell. It is a key enabler for 5G Non-Public Networks (NPNs) and network slicing, allowing enterprises to have dedicated, controlled wireless access.

Architecturally, a PRAS contains the full stack of the 5G NR radio protocol layers: the Physical Layer (PHY), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and the Radio Resource Control (RRC). It implements the gNB-DU (Distributed Unit) functionality as defined in the 5G RAN split architecture. The PRAS connects to the mobile operator's core network or a dedicated edge core network via a wired backhaul link, such as fiber, Ethernet, or xDSL. This connection typically uses the standard F1 interface to communicate with a centralized gNB-CU (Centralized Unit) or, in a simpler implementation, a more integrated interface towards a 5G Core (5GC). This backhaul connection carries both user plane data and control plane signaling.

From an operational perspective, the PRAS is managed by the mobile network operator or a neutral host, even though it is physically located on customer premises. Management can occur via standard interfaces like the O-RAN O1 interface or 3GPP-defined management interfaces. The PRAS supports key 5G features relevant to enterprise environments. This includes support for network slicing, allowing the operator to provision dedicated logical networks with specific performance characteristics (e.g., ultra-low latency, high reliability) for different applications or tenants within the premises. It also supports Quality of Service (QoS) mechanisms, uplink/downlink decoupling, and can be integrated with Mobile Edge Computing (MEC) platforms to host applications locally.

The role of the PRAS is to bridge the gap between public macro network coverage and dedicated private wireless solutions. It offers the performance, security, and customization benefits of a private network while leveraging the operator's spectrum, core network infrastructure, and management expertise. It differs from a traditional Femtocell (HeNB) by being a more capable, programmable, and slice-aware node designed for the scalable and diverse requirements of Industry 4.0, enterprise digital transformation, and precise indoor localization services.

Purpose & Motivation

The PRAS was created to address the growing demand from enterprises and industry verticals for high-performance, secure, and customizable wireless connectivity within their premises. Traditional macro network coverage often fails to provide the necessary capacity, ultra-reliable low-latency communication (URLLC), or data privacy required for critical industrial automation, augmented reality in warehouses, or sensitive healthcare applications. While Wi-Fi is ubiquitous, it lacks the deterministic performance, seamless mobility, and integrated security model of 3GPP systems.

Previous approaches included enterprise small cells and femtocells, but these were often limited in capability, tightly coupled to the public network's architecture, and not designed with network slicing or edge computing in mind. The motivation for standardizing the PRAS in 3GPP was to create a unified, vendor-interoperable model for premises-based 5G access that seamlessly integrates with operator networks. It solves the problem of providing 'network-as-a-service' inside private facilities, allowing operators to extend their service offerings beyond mere connectivity to include dedicated private network slices.

Furthermore, the PRAS facilitates new business models. It enables operators to deploy and manage radio infrastructure on customer sites without ceding control of the spectrum or core network. For enterprises, it offers a managed service alternative to building and maintaining their own private 5G network from scratch. The standardization in Release 18, as part of the broader '5G Advanced' evolution, was driven by use cases defined in 3GPP SA1 (TS 22.261 on 5G system phase 3, and TS 22.858 on network automation), highlighting the need for automated, flexible, and service-aware RAN deployments at the edge of the network, including on customer premises.

Key Features

• Deploys as Customer-Premises Equipment (CPE), providing localized 5G NR radio coverage indoors or on a campus.
• Connects to the operator's 5G Core network via wired backhaul (e.g., fiber, Ethernet) using standard 3GPP interfaces (e.g., F1).
• Supports 5G network slicing, enabling the creation of dedicated logical networks for different enterprise services or tenants.
• Can be integrated with Mobile Edge Computing (MEC) platforms to host applications locally for ultra-low latency services.
• Managed by the network operator or a neutral host via standardized management interfaces (e.g., O1, NETCONF/YANG).
• Enables enhanced indoor positioning and location-based services due to its precise, localized deployment.

Evolution Across Releases

Defining Specifications