5G NR QoS (Quality of Service): Architecture and Benefits

This page describes 5G NR QoS (Quality of Service) requirements. It mentions the 5G QoS architecture as per the 3GPP NR (New Radio) Standard. The benefits or advantages of 5G QoS are also explained. It also highlights the difference between 4G QoS and 5G QoS.

Introduction to QoS

QoS (Quality of Service) is very essential for mission-critical users and organizations for many reasons, especially in critical situations. Though there are dedicated proprietary networks for such needs, commercial networks such as 2G/3G/4G, and now 5G, are also being used. The use of commercial networks helps keep investment lower. Following are the basic requirements from mission-critical users/organizations:

• Define priorities between normal users and critical users.
• Define priorities between critical users and critical organizations.
• Define priorities between different types of information (voice/signaling/data).
• Emergency calls should be guaranteed to be served.
• Services should be guaranteed to be available during disasters and extreme conditions.

4G QoS vs 5G QoS

• 4G QoS: The concept of QoS in 4G LTE is based on bearers. An LTE bearer is a transmission path through the infrastructure and radio interface with a defined capacity, latency, and packet loss. The tools such as ACB (Access Class Barring), ARP (Allocation and Retention Priority), and QCI (QoS Class Identifier) help in managing QoS in the 4G LTE network. QCI has values in the range from 1 to 254. Each of these values has three attributes: priority, packet delay budget, and packet error loss.
• 5G QoS: The concept of QoS in 5G is flow-based. Packets are classified and marked using QFI (QoS Flow Identifier). The 5G QoS flows are mapped in the AN (Access Network) to DRBs (Data Radio Bearers), unlike 4G LTE where mapping is one-to-one between EPC and radio bearers.

It supports the following QoS flow types:

• GBR QoS flow, requires guaranteed flow bit rate.
• Non-GBR QoS flow, does not require guaranteed flow bit rate.

5G NR QoS Architecture

Figure 1: 5G NR QoS Architecture

The figure above depicts the 5G NR QoS architecture and various elements as defined in 3GPP TS 38.300 Release-15, published in June 2018. QoS architecture is used for both NR connected to 5GC and E-UTRA connected to 5GC.

• QoS flow is identified by QFI within the PDU session. This QFI is carried in an encapsulation header over NG-U.
• For each UE, 5GC establishes one or more PDU sessions, and NG-RAN establishes at least one DRB together with the PDU session. Additional DRBs are configured for QoS flows of that PDU session consecutively.
• NG-RAN maps packets which belong to the different PDU sessions to different DRBs.
• NAS level packet filters in UE and in 5GC associate UL/DL packets with QoS flows. At the NAS level, QoS flow is characterized by a QoS profile provided by 5GC to NG-RAN and QoS rules provided by 5GC to UE.
• AS-level mapping rules in UE and in NG-RAN associate UL/DL QoS flows with DRBs. At the AS (Access Stratum) level, DRB defines packet treatment on the radio interface (Uu).

The QoS profile of a QoS flow contains QoS parameters as mentioned below:

• For each QoS flow: 5QI (5G QoS Identifier), ARP
• For GBR QoS flow only: GFBR (Guaranteed Flow Bit Rate), MFBR (Maximum Flow Bit Rate), and maximum packet loss rate for both uplink and downlink.
• For Non-GBR QoS only: Reflective QoS Attribute (RQA)

QoS characteristics consist of an instance of the following parameters:

• Resource Type (GBR, delay critical GBR, or non-GBR)
• Priority level
• Packet Delay Budget
• Packet Error Rate
• Averaging Window
• Maximum Data Burst Volume

Benefits or Advantages of 5G QoS in NR (New Radio)

Following are the benefits or advantages of 5G QoS in NR:

• It delivers critical communication services for mission-critical users/organizations.
• It provides different prioritization levels for different applications as per users preset requirements with the operators.
• It provides help to people during disasters and emergency situations such as floods, earthquakes, etc.
• The service is always available for emergency callers.