User experienced data rate

Description

User experienced data rate is a key performance indicator (KPI) in 3GPP networks, defined as the minimum data rate required to achieve a sufficient quality experience, with the exception of broadcast-like services where the given value is the maximum that is needed. This metric is used to characterize the data rate that a user actually experiences in real-world conditions, taking into account factors such as network load, signal quality, and mobility. It is distinct from peak data rate, which represents the theoretical maximum achievable under ideal conditions.

The concept of user experienced data rate was introduced in Release 15 as part of the 5G performance requirements, particularly in the context of enhanced Mobile Broadband (eMBB) and other usage scenarios. It is defined in specifications such as 3GPP TS 22.261 (Service requirements for the 5G system) and TS 22.104 (Service requirements for cyber-physical control applications in vertical domains). The metric is used to specify the minimum performance that a user should receive to have a satisfactory experience for a given service. For example, for video streaming, a certain minimum data rate is needed to avoid buffering and ensure smooth playback.

User experienced data rate is typically measured at the application layer, reflecting the throughput perceived by the user. It can be expressed as a cumulative distribution function (CDF) of the data rate achieved by users across the coverage area. The 3GPP defines target values for user experienced data rate for different scenarios. For instance, for urban macro eMBB, the target is 100 Mbit/s for downlink and 50 Mbit/s for uplink. For indoor hotspot, the targets are higher, such as 1 Gbit/s downlink. These targets are used by operators and vendors to design and optimize networks.

The metric is influenced by many factors, including the number of users sharing the cell, the distance from the base station, the amount of interference, and the scheduling algorithm. To achieve the target user experienced data rate, networks employ techniques such as massive MIMO, carrier aggregation, and advanced scheduling. The 5G System is designed to provide a user experienced data rate of at least 100 Mbit/s in dense urban areas, and up to 1 Gbit/s in indoor hotspots.

In addition to eMBB, user experienced data rate is also relevant for other 5G usage scenarios. For ultra-reliable low-latency communication (URLLC), the focus is more on latency and reliability, but a certain data rate is still required for the application. For massive machine-type communication (mMTC), the data rate per device is typically low, but the metric may still apply to ensure that devices can transmit their data within a reasonable time. For broadcast-like services, such as TV broadcasting, the user experienced data rate represents the maximum data rate needed to deliver the service, as all users receive the same stream.

The user experienced data rate is a crucial metric for evaluating the quality of service from the user's perspective. It helps operators to dimension their networks, set performance targets, and ensure customer satisfaction. It is also used in regulatory contexts to define minimum service levels. As networks evolve towards 5G-Advanced and 6G, the target user experienced data rates continue to increase, driven by new applications such as immersive extended reality (XR) and holographic communications.

Purpose & Motivation

User experienced data rate was introduced to provide a user-centric metric for network performance, shifting the focus from theoretical peak rates to the actual data rates that users perceive. Traditional metrics like peak data rate do not reflect real-world conditions, where users may experience lower rates due to network congestion, signal attenuation, or mobility. The user experienced data rate addresses this gap by specifying the minimum data rate needed for a satisfactory quality of experience (QoE) for a given service.

The metric was motivated by the diverse requirements of 5G services, which range from high-speed broadband to low-rate IoT. For eMBB, users expect seamless video streaming and fast downloads, requiring a certain minimum data rate. For broadcast-like services, the metric defines the maximum rate needed to deliver the content to all users simultaneously. By defining target values for user experienced data rate, 3GPP provides a clear benchmark for network design and optimization.

Historically, earlier generations of mobile networks focused on peak data rates and average throughput. However, as networks became more complex and user expectations grew, it became clear that a more nuanced metric was needed. The user experienced data rate captures the actual performance that users receive, enabling operators to identify and address areas of poor coverage or capacity. It also facilitates fair comparison between different network deployments and technologies. As 5G and beyond evolve, the user experienced data rate will remain a key KPI for ensuring that networks meet the demands of emerging applications.