Wide Area Network

Description

Within 3GPP standardization, the term Wide Area Network (WAN) is used to describe the conventional, large-scale cellular network deployment that provides ubiquitous coverage over cities, regions, or countries. Technically, a 3GPP WAN is characterized by its use of macro cell sites with base stations (NodeBs, eNodeBs, gNBs) mounted on towers or rooftops, offering coverage radii typically ranging from several hundred meters to tens of kilometers. The WAN forms the primary infrastructure for public mobile broadband and voice services, operating in licensed spectrum bands. Its architecture follows the hierarchical 3GPP system architecture, comprising the Radio Access Network (RAN) and the Core Network (CN), interconnected via backhaul links.

The WAN works by dividing a geographical area into cells, each served by a base station. Through advanced techniques like handover, power control, and interference coordination, it provides continuous mobility support to users traveling across cells. The core network manages subscriber authentication, session management, mobility anchoring, and connectivity to external networks like the internet. In 3GPP studies, especially from Release 8 onwards with LTE and later 5G, 'WAN' is frequently used as a baseline or reference scenario. For instance, when evaluating new radio technologies or network architectures, performance and requirements are often compared against 'WAN' characteristics to ensure they meet the expectations for wide-area service.

Furthermore, 3GPP uses the term to differentiate service scenarios. A 'WAN scenario' implies expectations of high mobility, continuous coverage, and support for a wide mix of services. This contrasts with 'hotspot' or 'local area' scenarios which target very high capacity in dense, small areas. In the context of integrated access and backhaul (IAB) or non-terrestrial networks (NTN), 'WAN' typically refers to the terrestrial macro-cell network that may be supplemented or extended by these other technologies. Thus, in 3GPP parlance, WAN is not just a generic IT term but a specific operational context that drives key performance indicators (KPIs) for coverage, mobility, and capacity in standardization work.

Purpose & Motivation

The explicit use and definition of 'Wide Area Network' within 3GPP specifications serve to establish a clear, common technical context for requirements and feasibility studies. As 3GPP began studying advanced technologies like LTE-Advanced, 5G, and network slicing, it became necessary to define distinct deployment scenarios to tailor performance targets. The WAN scenario represents the foundational use case of mobile networks: providing seamless service over a wide geographical area, which is the primary business of most operators.

This formalization addresses the problem of ambiguity when discussing network capabilities. By defining WAN characteristics, 3GPP can set specific requirements for aspects like mobility support (e.g., up to 500 km/h for high-speed trains), coverage reliability (e.g., 95% area coverage), and latency for services deployed over such an area. It creates a benchmark against which enhancements (like small cells or millimeter-wave deployments) can be evaluated. The motivation stems from the need to ensure that new radio access technologies (RATs) or network features do not compromise the core wide-area service while pursuing gains in peak data rates or capacity.

Its inclusion in studies from Release 8 onwards reflects the evolving landscape where cellular networks were no longer just WANs but were integrating with and being compared to other network types (e.g., WLAN for local access). Defining the WAN scenario helps in designing systems that are optimized for broad coverage and mobility first, with other features like extreme capacity being added for specific scenarios. It ensures the standard continues to serve the fundamental requirement of providing reliable mobile communication anywhere within a national or regional footprint.