One of the primary mechanisms that LTE networks use to handle prioritization of traffic during congestion are quality of service class identifiers (also called QCI values). Without getting too technical, QCI values indicate a certain priority level for traffic. Most data use by regular consumers on LTE networks will involve QCI values between 6 and 9. Within that range, lower QCI values are associated with higher-priority service. For a much more technical treatment of QCI values, see the 3GPP publication on Policy and charging control architecture.
Observed QCI Values
I’ve started to run tests to figure out QCI values associated with different carriers’ service. I hope to run test like these with more carriers in the future. More information on how I run these tests can be found here.
Carriers using AT&T’s network
I found a QCI of 8 for regular data use on a non-unlimited Cricket plan on 5/17/2020.
Carriers using T-Mobile’s network
I found a QCI value of 6 for regular data use on Fi’s service on 9/17/2019.
I found a QCI value of 6 for regular data use on a T-Mobile Connect plan on 5/14/2020.
I found a QCI value of 7 for regular data use with Mint Mobile’s service on 9/17/2019.
Carriers using Verizon’s network
I found a QCI of 9 for regular data use on a second-generation Xfinity Mobile unlimited plan on 5/19/2020.
Standardized QCI characteristics
The following table is a modified and abbreviated version of what appears in the 3GPP standards.
|QCI||Resource Type||Priority Level||Packet Delay Budget||Packet Error Loss Rate||Example Services|
|1||Guaranteed Bit Rate (GBR)||2||100 ms||10-2||Conversational Voice|
|2||GBR||4||150 ms||10-3||Conversational Video (Live Streaming)|
|3||GBR||3||50 ms||10-3||Real Time Gaming; V2X messages|
|4||GBR||5||300 ms||10-6||Non-Conversational Video (Buffered Streaming)|
|65||GBR||0.7||75 ms||10-2||Mission Critical user plane Push To Talk voice (e.g., MCPTT)|
|66||GBR||2||100 ms||10-2||Non-Mission-Critical user plane Push To Talk voice|
|67||GBR||1.5||100 ms||10-3||Mission Critical Video user plane|
|75||GBR||2.5||50 ms||10-2||V2X messages|
|5||Non-GBR||1||100 ms||10-6||IMS Signalling|
|6||Non-GBR||6||300 ms||10-6||Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)|
|7||Non-GBR||7||100 ms||10-3||Voice; Video (Live Streaming); Interactive Gaming|
|8||Non-GBR||8||300 ms||10-6||Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)|
|9||Non-GBR||9||300 ms||10-6||Same as above|
|69||Non-GBR||0.5||60 ms||10-6||Mission Critical delay sensitive signalling (e.g., MC-PTT signalling, MC Video signalling)|
|70||Non-GBR||5.5||200 ms||10-6||Mission Critical Data (e.g. example services are the same as QCI 6/8/9)|
|79||Non-GBR||6.5||50 ms||10-2||V2X messages|
|80||Non-GBR||6.8||10 ms||10-6||Low latency eMBB applications (TCP/UDP-based); Augmented Reality|
- Other mechanisms include guaranteed bit rates, maximal bit rates, and allocation and retention priority. The excerpt below comes from page 51 of 3GPP TS 23.203 V16.1.0:
“The service level (i.e., per SDF or per SDF aggregate) QoS parameters are QCI, ARP, GBR, and MBR.”
- I did this using a device that was compatible with Fi but not designated “Designed for Fi.”
- Based on Table 6.1.7-A: Standardized QCI characteristics from 3GPP TS 23.203 V16.1.0.