Vertical Application Layer Service

Description

A VAL (Vertical Application Layer) service is a broad term that encompasses any service delivered by a VAL service provider to its users, leveraging the capabilities of a 3GPP network. It represents the application-level service that a vertical industry (e.g., manufacturing, automotive, health, entertainment) offers to its end users or customers. The VAL service is not a specific protocol or function but a conceptual entity that defines the service-level agreement between the provider and the user, including the functional and performance requirements. Examples include real-time video surveillance, drone control, industrial automation, and immersive AR/VR experiences. The VAL service is realized through the interaction of a VAL client (in the UE) and a VAL server (in the application domain), which together implement the service logic. The 3GPP specifications TS 23.434 and TS 29.549 define the architecture and APIs that enable VAL services to be deployed over 3GPP networks.

From an architectural perspective, a VAL service is part of the vertical application layer, which sits above the 3GPP network. The VAL service provider is responsible for the service logic, user management, and possibly data storage, while the 3GPP network provides connectivity, QoS, mobility, and other network functions. The VAL service can be hosted on a VAL server, which communicates with VAL clients in UEs via the 3GPP network. The service may also utilize enablers such as SEAL (Service Enabler Architecture for Verticals) for common functions like group management, location reporting, and configuration management. The VAL service can be offered to a closed group (e.g., employees of a factory) or to the public (e.g., a consumer AR game).

How it works: A VAL user (e.g., a worker with an AR headset) accesses the VAL service through a VAL client application on their UE. The client connects to the VAL server, which authenticates the user and establishes a service session. The VAL server then orchestrates the necessary network resources by requesting appropriate QoS, establishing data sessions, and possibly enabling edge computing. For example, for a video streaming service, the VAL server may request a guaranteed bit rate and low latency from the 5G Core, and may also interact with a MEC (Multi-access Edge Computing) platform to host content closer to the user. The VAL service may involve multiple UEs, in which case the VAL server coordinates group communication, possibly using 3GPP's group communication enablers like 5G MBS (Multicast-Broadcast Services) or MCVideo (Mission Critical Video).

Key components of a VAL service include the service logic (implemented in the VAL server and client), the service level agreements (SLAs) that define performance and reliability requirements, and the service management functions (e.g., user provisioning, billing). The VAL service may also include security mechanisms, such as authentication and authorization, to ensure that only authorized users can access the service and that data is protected. The service can be deployed in various configurations: entirely on-premises, entirely in the cloud, or hybrid, depending on the latency, data privacy, and scalability requirements.

In the broader network context, the VAL service is the reason for the existence of the VAL architecture. It represents the demand side (vertical industries) that 3GPP aims to serve. By defining a generic VAL service, 3GPP enables a wide range of verticals to use the same underlying network capabilities without requiring customizations to the core network. This promotes economies of scale and accelerates the adoption of 5G in vertical domains. The term 'VAL service' is intentionally generic to cover all possible vertical services, from mission-critical push-to-talk to smart factory control. With Release 19, 3GPP provided a common definition to facilitate discussions and specifications related to vertical services. The definition remained unchanged in Release 20, indicating a stable concept.

Purpose & Motivation

The VAL service concept exists to provide a unified terminology for the diverse set of services that vertical industries can offer over 3GPP networks. Before its introduction, there was no standard way to refer to these services; each vertical might have its own naming and architectural assumptions. This led to fragmentation in specifications and difficulty in creating a common framework for network integration. The VAL service abstraction solves this by defining a generic service entity that can be used across all verticals, allowing 3GPP to develop common enablers (like SEAL) and network exposure mechanisms (like NEF) that apply to any VAL service.

Another motivation is to facilitate the mapping of vertical service requirements to 3GPP network capabilities. By having a clear definition of a VAL service, network operators and vertical service providers can better communicate about the necessary QoS, mobility, security, and management features. It also helps in the development of standardized APIs (e.g., in TS 29.549) that allow VAL services to request network services dynamically. This is essential for enabling on-demand, context-aware service delivery that can adapt to changing network conditions or user needs.

The VAL service concept was introduced in Release 19 as part of the Vertical Application Layer (VAL) work item. It builds on earlier efforts such as the Service Capability Exposure Function (SCEF) and the Common API Framework (CAPIF). The generic definition ensures that the term can encompass services with very different characteristics, from ultra-reliable low-latency to massive IoT. This flexibility is key to 3GPP's goal of making 5G a platform for all industries. The definition remained unchanged in Release 20, showing that the concept has been stable and widely accepted.