Private network slice

Description

A private slice is a dedicated network slice deployment for the sole use by a specific third party, such as an enterprise, government agency, or vertical industry. It is a key concept in 5G networks, introduced in 3GPP Release 16, and builds upon the network slicing framework defined for 5G. Unlike public slices that serve multiple tenants, a private slice is exclusively allocated to one tenant, offering enhanced isolation, security, and performance guarantees.

The architecture of a private slice involves the creation of a logical network that spans the Radio Access Network (RAN), Core Network (CN), and Transport Network (TN). It is instantiated using Network Slice as a Service (NSaaS) principles, where the slice is tailored to the specific requirements of the tenant. The slice can be deployed on the operator's infrastructure, on the tenant's premises, or in a hybrid manner. Key components include the Slice Management Function (SMF), Network Slice Selection Function (NSSF), and the various network functions (NFs) that constitute the slice. The tenant may have varying degrees of control, from monitoring to full management of the slice.

How it works: The tenant requests a private slice from the operator, specifying requirements such as coverage, capacity, latency, reliability, and security. The operator designs and deploys the slice using network slicing techniques, including resource isolation, dedicated NFs, and customized QoS policies. The slice is identified by an S-NSSAI (Single Network Slice Selection Assistance Information), which is used by the UE and network to select the appropriate slice. The NSSF assists in selecting the slice during registration. The private slice can be accessed by UEs that are authorized for that slice, typically employees or devices of the tenant. The slice can be isolated from other slices at various levels: physical, virtual, or logical.

Key components of a private slice include the RAN slice (e.g., dedicated gNBs or shared RAN with slice-aware scheduling), the CN slice (e.g., dedicated AMF, SMF, UPF), and the transport slice (e.g., VLANs, segment routing). Security is paramount, with mechanisms such as slice-specific authentication and authorization, encryption, and isolation to prevent cross-slice attacks. The tenant may also deploy their own application functions within the slice, integrating with the 5G core.

Private slices are particularly relevant for industrial IoT, smart factories, public safety, and campus networks. They enable enterprises to have a dedicated, secure, and high-performance network without building their own physical infrastructure. The concept has evolved from Release 16 to Release 20, with ongoing enhancements in areas like slice management, automation, and inter-slice communication. The definition has remained consistent, emphasizing sole use by a specific third party.

Purpose & Motivation

Private slices exist to meet the demanding requirements of vertical industries and enterprises that need dedicated, isolated, and customized network services. Before network slicing, enterprises had to rely on either public networks with limited customization or build their own private networks using unlicensed or licensed spectrum, which was costly and complex. Network slicing in 5G introduced the ability to create multiple logical networks on a shared infrastructure, but public slices still served multiple tenants, potentially compromising isolation and performance.

Private slices solve this by providing a slice exclusively for one tenant, ensuring that resources are not shared with others. This is crucial for applications requiring ultra-reliable low-latency communication (URLLC), enhanced mobile broadband (eMBB), or massive machine-type communication (mMTC) with strict SLAs. For example, a factory may need a private slice to control robots with deterministic latency, or a hospital may need a private slice for secure patient data transmission.

The motivation for private slices also includes regulatory and security requirements. Some enterprises, such as government or defense, require complete isolation from public traffic. Private slices provide the necessary isolation and control. Additionally, private slices enable new business models for operators, who can offer tailored slice-as-a-service to enterprises, generating new revenue streams. The concept aligns with the broader 5G vision of supporting diverse use cases through network slicing.