Application priority services including field measurements

As a precursor to slicing in future 5G, KPN introduces a new service that can also work on the LTE network: Application Priority service. The initial target segment of the service is for critical Internet of Things (IoT) and other end-points with low data bandwidth demand. This paper explains the mechanisms and the technical implementation used to deliver the Application Service. It also provides the TNO measurement results verifying the working of the Application Service under different circumstances. The implementation of the Application Priority service pivots around three mechanisms: Access Class, Admission and Retention, and Minimum Bitrate. The Access Class is set on the mobile device of an Application Priority user. A high priority Access Class ensures that the device can always signal the network in order to set up a connection. This can also result in standard devices being prevented to signal the network for a connection. Admission and Retention then determines if that connection is actually setup. If insufficient resources are available, existing (standard) connections can even be deactivated (pre-empting). The same mechanism also ensures that once the connection is established, it stays up. The third mechanism that is essential for the Application Priority service to work, is a Minimum Bitrate. This Minimum Bitrate is the bitrate that is reserved for an Application Priority connection once that connection is setup. As a result, even during extreme congestion, Application Priority service users can setup a connection and obtain a prioritized bitrate equal to the minimum bitrate of 200kb/s. Under normal circumstances, in a non-congested network, the bitrate is limited to a non-prioritized maximum bitrate of 5Mb/s. Due to the COVID-19 intelligent lockdown, there were no extremely congested radio cells in the mobile network to carry out the measurements. Therefore, TNO performed the measurements at the KPN office in The Hague. The location has a base station to provide indoor coverage and is part of KPN’s public mobile network. Here KPN was able to limit the capacity in the radio part to mimic congestion. This enabled TNO to perform the tests with only a limited number of handsets. From the test results of the Application Priority service, we can draw the following conclusions: - The working of the Minimum Target Bitrate (MTB). This is verified. Although it could only be tested with an increased MTB, the Application Priority test-phone saw a throughput at MTB-level with heavy congestion, while the standard test-phone had much lower throughput; - The working of pre-emption is verified: The Application Priority service is less pre-emption vulnerable than the standard service; The Application Priority service is also pre-emption capable; - The maximum bitrate of 5Mb/s for the Application Priority test-phone was also observed, but it turned out not to be a hard limit. Most likely since it can take time in the gateway to throttle the throughput when exceeded.