Person to Person

Description

Person to Person (P2P) is a 3GPP Release 19 term that encompasses communication services directly between individuals, as opposed to machine-to-machine (M2M) or person-to-machine interactions. P2P covers a broad range of services including voice and video calls, instant messaging, file sharing, presence, and social networking interactions. In the 3GPP context, P2P is addressed across multiple specifications: TS 23.228 (IP Multimedia Subsystem architecture), TS 24.186 (IMS conferencing), TS 26.567 (5G media streaming for P2P), TS 28.851 (management of P2P services), and TS 33.790 (security for P2P communications).

Architecturally, P2P services in 3GPP are built on the IP Multimedia Subsystem (IMS) for real-time communication and on 5G Media Streaming (5GMS) for media delivery. The IMS provides session control, registration, authentication, and service invocation for voice and video calls. The 5GMS framework provides media streaming, content delivery, and application-layer signaling for richer P2P media experiences. For proximity-based P2P communication, 3GPP defines Proximity Services (ProSe) that allow devices to communicate directly over the PC5 interface without traversing the core network, enabling low-latency and offload scenarios.

Key components of the P2P framework include: the P2P application server, which manages user registration, presence, and session establishment; the IMS core, which provides SIP-based session control; the 5GMS Application Function and Application Server, which handle media delivery and content adaptation; the ProSe Function, which manages direct discovery and communication; and the security framework, which provides authentication, confidentiality, and integrity protection for P2P sessions. These components interact through standardized interfaces to deliver seamless P2P services across access networks and devices.

P2P services operate in several modes. In infrastructure-based mode, all signaling and media traverse the 3GPP core network, providing centralized control and QoS guarantees. In direct mode, devices communicate over the PC5 interface, which is useful for public safety, offloading, and low-latency applications. In hybrid mode, devices use both direct and infrastructure paths, with the network managing the transition. The choice of mode depends on factors such as proximity, network load, QoS requirements, and regulatory constraints.

In terms of network integration, P2P services leverage 5G capabilities such as network slicing, QoS differentiation, and edge computing. For example, a P2P video call can be assigned to a slice optimized for low-latency communication, while a file-sharing session can use a slice optimized for high throughput. Edge computing can host P2P application servers close to users, reducing latency and backhaul load. Security is a critical aspect, with 3GPP defining mechanisms for user authentication, media encryption, and privacy protection. Overall, P2P in Rel-19 represents the continued evolution of interpersonal communication services in 5G-Advanced networks, integrating IMS, 5GMS, and ProSe to deliver rich, secure, and efficient P2P experiences.

Purpose & Motivation

P2P exists to provide standardized, interoperable communication services between individuals over 3GPP networks. While basic voice and messaging services have existed since the early days of cellular networks, the evolution to all-IP networks and the proliferation of rich media applications created a need for a comprehensive framework that supports real-time voice, video, messaging, presence, and content sharing across heterogeneous devices and access networks. P2P addresses this need by defining architectures, protocols, and procedures for interpersonal communication.

The motivation for P2P in 3GPP Release 19 comes from several factors. First, the convergence of telecommunication and internet services means that users expect seamless communication across multiple platforms and devices. Second, the growth of 5G capabilities such as network slicing, edge computing, and high-reliability low-latency communication enables new P2P use cases such as immersive video calls, cloud gaming, and collaborative applications. Third, the need for public safety and mission-critical communication requires direct device-to-device communication that can operate without network infrastructure. Fourth, regulatory requirements for emergency services and lawful interception require standardized P2P architectures.

Historically, previous approaches to P2P communication were fragmented across different technologies: circuit-switched voice, SMS, MMS, and proprietary over-the-top (OTT) applications. While OTT applications provide rich functionality, they lack the QoS guarantees, security, and regulatory compliance of standardized 3GPP services. 3GPP P2P aims to combine the flexibility and richness of OTT services with the reliability, security, and manageability of operator-controlled networks. By standardizing P2P across IMS, 5GMS, and ProSe, 3GPP enables operators to offer competitive P2P services while maintaining control over QoS, security, and charging. This approach also facilitates interoperability between operators and between 3GPP and non-3GPP networks, ensuring that users can communicate seamlessly regardless of their location or access technology.