5G NR Bandwidth Part: Concepts and Functions Explained

This page introduces the basics of 5G NR Bandwidth Parts (BWPs), including their function. The different use cases of bandwidth parts in the 5G NR standard are also covered.

Introduction

The bandwidth part concept was introduced in 5G NR to reduce power consumption in user equipment (UE) devices. To achieve this, the UE operates on a wide bandwidth in bursty traffic situations for short periods. For the remaining time, it remains active on a narrower bandwidth. This is known as bandwidth adaptation.

A bandwidth part (BWP) is a subset of contiguous Resource Blocks (RBs) on a carrier.

• A bandwidth part is a subset of contiguous RBs on the carrier.
• Up to four bandwidth parts can be configured for the UE for each of the uplink (UL) and downlink (DL).
• However, at any given time, only one bandwidth part is active per transmission direction (either UL or DL).

Thanks to the BWP concept, the UE can receive on a narrow bandwidth part, and when needed, the network instructs the UE to switch to a wider bandwidth for reception.

Use cases of Bandwidth part in 5G NR

• Carrier bandwidth part (BWP) is a contiguous subset of Physical Resource Blocks (PRBs) defined for a given 5G NR numerology on a specific component carrier.
• One or multiple BWP configurations for each component carrier can be assigned to the UE. But only one BWP in the downlink (DL) and one in the uplink (UL) is active at a given time instant.
• Consequently, the UE cannot transmit PUSCH (Physical Uplink Shared Channel) or PUCCH (Physical Uplink Control Channel), and cannot receive PDSCH (Physical Downlink Shared Channel) or PDCCH (Physical Downlink Control Channel) outside of an active BWP.
• Configuration parameters for each BWP include numerology, bandwidth size, frequency location, and CORESET (Control Resource Set).

The different use cases of bandwidth parts in 5G NR standard-based devices are shown in Figure 2.

• (A) - Supports reduced UE bandwidth capability
• (B) - Supports reduced UE energy consumption
• (C) - Supports FDM (Frequency Division Multiplexing) of different numerologies
• (D) - Supports non-contiguous spectrum
• (E) - Supports forward compatibility