5G aims to offer not only significantly higher throughput than previous generations of cellular networks, but also promises millisecond (ms) and sub-millisecond (ultra-)low latency support at the 5G physical (PHY) layer for future applications. While prior measurement studies have confirmed that commercial 5G deployments can achieve up to several Gigabits per second (Gbps) throughput (especially with the mmWave 5G radio), are they able to deliver on the (sub) millisecond latency promise? With this question in mind, we conducted to our knowledge the first in-depth measurement study of commercial 5G mmWave PHY latency using detailed physical channel events and messages. Through carefully designed experiments and data analytics, we dissect various factors that influence 5G PHY latency of both downlink and uplink data transmissions, and explore their impacts on end-to-end delay. We find that while in the best cases, the 5G (mmWave) PHY-layer is capable of delivering ms/sub-ms latency (with a minimum of 0.09 ms for downlink and 0.76 ms for uplink), these happen rarely. A variety of factors such as channel conditions, re-transmissions, physical layer control and scheduling mechanisms, mobility, and application (edge) server placement can all contribute to increased 5G PHY latency (and thus end-to-end (E2E) delay). Our study provides insights to 5G vendors, carriers as well as application developers/content providers on how to better optimize or mitigate these factors for improved 5G latency performance.
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An In-Depth Study of Uplink Performance of 5G mmWave Networks
The highly anticipated 5G mmWave technology promises to enable
many uplink-oriented, latency-critical applications (LCAs) such as
Augmented Reality and Connected Autonomous Vehicles. Nonetheless,
recent measurement studies have largely focused on its downlink
performance. In thiswork,we perform a systematic study of the
uplink performance of commercial 5G mmWave networks across
3 major US cities and 2 mobile operators. Our study makes three
contributions. (1) It reveals that 5G mmWave uplink performance
is geographically diverse, substantially higher over LTE in terms of
bandwidth and latency, but often erratic and suboptimal, which can
degrade LCA performance. (2) Our analysis of control messages
and PHY-level KPIs shows that the root causes for the suboptimal
performance are fundamental to 5G mmWave and cannot be easily
fixed via simple tuning of network configurations. (3) We identify
various design and deployment optimizations that 5G operators
can explore to bring 5G mmWave performance to the level needed
to ultimately support the LCAs.
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- Award ID(s):
- 2112778
- NSF-PAR ID:
- 10343030
- Date Published:
- Journal Name:
- Proceedings of The 2nd ACM SIGCOMM Workshop on 5G and Beyond Network Measurements, Modeling, and Use Cases (5G-MeMU)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3538394.3546042
