Wideband E-UTRAN

Description

WB-E-UTRAN (Wideband E-UTRAN) is a 3GPP term that refers to the portion of the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) that supports wideband communications, specifically excluding narrowband Internet of Things (NB-IoT) technologies. E-UTRAN, also known as LTE, is the radio access network for 4G LTE and consists of eNodeBs (base stations) that provide wireless connectivity to User Equipment (UE). WB-E-UTRAN encompasses the traditional LTE access that supports mobile broadband services with channel bandwidths typically ranging from 1.4 MHz to 20 MHz, as opposed to the narrow 180 kHz bandwidth used by NB-IoT. In the Radio Access Network context, WB-E-UTRAN is defined as the part of E-UTRAN that excludes NB-IoT, meaning it covers standard LTE, LTE-Advanced, and LTE-Advanced Pro features, including carrier aggregation, MIMO, and higher-order modulation. In the Core Network context, WB-E-UTRAN also excludes LTE-M (LTE-Machine Type Communication, also known as eMTC), which is a complementary technology optimized for IoT with reduced bandwidth (1.08 MHz) and extended coverage. This distinction is crucial for core network procedures, such as mobility management, session management, and policy control, where the characteristics of the access network influence parameters like QoS, paging, and location management. The definition further clarifies that unless otherwise stated in a specification, WB-E-UTRAN includes satellite access. This inclusion reflects the integration of satellite components into terrestrial networks, particularly in later releases (Rel-17 onwards), where satellite access can be part of E-UTRAN via non-terrestrial networks (NTN) for coverage extension. WB-E-UTRAN is referenced in key specifications such as TS 23.203 (Policy and Charging Control), TS 23.401 (GPRS enhancements for E-UTRAN), TS 23.682 (Architecture enhancements for Machine-Type Communications), and TS 29.212 (Policy and Charging Control over Gx reference point). The term helps differentiate wideband LTE from narrowband IoT radio access types, ensuring that core network functions apply appropriate handling based on the access technology's capabilities. As networks evolve towards 5G, the concept of WB-E-UTRAN remains relevant for interworking between 4G and 5G, particularly for dual-connectivity and fallback scenarios, and for supporting legacy devices and services.

Purpose & Motivation

The term WB-E-UTRAN was introduced to address the growing diversity of radio access technologies within the LTE ecosystem, specifically to distinguish between wideband LTE access designed for mobile broadband services and narrowband access optimized for IoT devices. As NB-IoT and LTE-M were developed to cater to massive machine-type communications with low power, low data rate, and extended coverage requirements, it became necessary to clearly identify the baseline LTE access that supports traditional human-centric services. This distinction ensures that core network procedures, such as policy and charging control, can apply different rules based on the capabilities and constraints of the access technology. For example, NB-IoT devices may have different QoS parameters, paging cycles, and mobility patterns compared to smartphones on wideband LTE. By defining WB-E-UTRAN, 3GPP provides a precise reference that avoids ambiguity in specifications and implementations, enabling operators to deploy mixed-mode networks where wideband and narrowband access coexist. The exclusion of LTE-M in the core network context further refines the definition, as LTE-M, while wider than NB-IoT, is still optimized for IoT and may not support the full range of wideband features. The inclusion of satellite access in later releases reflects the technological evolution towards integrating non-terrestrial networks into the 5G and 4G ecosystem. Satellite access can be considered part of WB-E-UTRAN when it provides wideband services, such as in NTN deployments, and its inclusion ensures that specifications cover emerging hybrid terrestrial-satellite architectures. Overall, WB-E-UTRAN serves as a clarifying term that facilitates precise technical documentation and implementation in an increasingly heterogeneous Radio Access Network landscape.