Vertical Application Layer System

Description

The VAL (Vertical Application Layer) system is a comprehensive term that refers to the entire set of components—applications, services, and enabling capabilities—that are necessary to deliver a VAL service to end users. It encompasses not only the VAL server and VAL client but also the underlying network enablers, management functions, and any supporting infrastructure. In essence, the VAL system is the end-to-end solution that a VAL service provider deploys to offer a vertical service. For example, a smart factory VAL system would include the factory automation application (server and client), the SEAL enablers for group management and location, the 5G network capabilities (e.g., URLLC, network slicing), and the management and orchestration functions. The 3GPP specifications TS 23.434 and TS 29.549 define the architecture and interactions within the VAL system, ensuring interoperability and standardized interfaces.

Architecturally, the VAL system spans multiple domains: the vertical application layer (where VAL servers and clients reside), the 3GPP network (which provides connectivity and network services), and possibly the edge computing domain (e.g., MEC). The VAL system can be seen as a superset of the VAL service; the service is what the user consumes, while the system is what the provider deploys and operates. The system includes the service logic, data storage, user management, security functions, and network integration components. It may also include tools for monitoring, analytics, and service assurance. The VAL system is typically owned and managed by the VAL service provider, but it relies on the 3GPP network operator for connectivity and network services. The boundary between the VAL system and the 3GPP network is defined by the standardized APIs (e.g., those in TS 29.549) that allow the VAL system to request network capabilities.

How it works: The VAL system operates by coordinating its various components to deliver the VAL service. When a VAL user accesses the service, the VAL client in the UE communicates with the VAL server, which is part of the VAL system. The VAL server then interacts with other system components, such as databases, authentication servers, and network enablers, to fulfill the user's request. For instance, in a video surveillance VAL system, the VAL server would receive video streams from cameras (VAL clients), process them (possibly using AI/ML models), store them, and provide access to authorized users. The system would also request appropriate QoS from the 3GPP network to ensure smooth video transmission. If the service requires group communication, the VAL system would use SEAL group management to create and manage groups. The system may also integrate with network exposure functions (NEF) to access network APIs for location, QoS, etc.

Key components of a VAL system include the VAL server(s) and VAL client(s), which implement the service logic; the SEAL enablers, which provide common services like group management, location management, and configuration management; the 3GPP network functions, which provide connectivity and network services; and management functions for orchestration, monitoring, and lifecycle management. The VAL system may also include edge computing platforms to host applications closer to the user, reducing latency. The system is designed to be modular, allowing the reuse of enablers across different VAL services.

In the broader network context, the VAL system is the realization of the vertical application layer concept. It represents the deployment and operational aspect of vertical services, as opposed to the abstract service definition. The VAL system is crucial for ensuring that vertical services can be delivered with the required performance, reliability, and security. It allows vertical service providers to focus on their domain expertise while leveraging standardized 3GPP capabilities. With Release 19, 3GPP defined the VAL system to provide a holistic view of the components needed for a vertical service. The definition remained unchanged in Release 20, indicating a stable and well-understood concept.

Purpose & Motivation

The VAL system concept exists to provide a holistic, end-to-end view of what is required to deliver a vertical service over 3GPP networks. Before its introduction, discussions about vertical services often focused on individual components (e.g., the server or the network) without a clear framework for how they fit together. This made it difficult to design, deploy, and manage complete solutions, especially in multi-vendor environments. The VAL system definition solves this by explicitly defining the collection of applications, services, and enabling capabilities that constitute the complete solution. This helps in standardizing interfaces, identifying gaps, and ensuring that all necessary components are considered.

Another motivation is to facilitate the deployment and operation of vertical services. By defining a VAL system, 3GPP provides a blueprint that service providers can follow to build their solutions. It also helps network operators understand what they need to expose to enable vertical services, and what service level agreements are appropriate. The VAL system concept emphasizes that delivering a vertical service is not just about connectivity; it requires a comprehensive system that includes application logic, enablers, and management. This is particularly important for mission-critical and industrial services where reliability and performance are paramount.

The VAL system concept was introduced in Release 19 as part of the VAL work item. It builds on the earlier definition of VAL service and VAL server, providing the overarching system view. The generic definition ensures that it can apply to any vertical, from smart cities to connected cars. The definition remained unchanged in Release 20, showing that the concept has been stable and widely accepted. The VAL system is a key enabler for 3GPP's vision of 5G as a platform for vertical industries, as it provides a common language and framework for all stakeholders.