Long Term Evolution (Advanced) - LTE(-A)
Services and applications in LTE/LTE-A

Like in former mobile communication standards, LTE/LTE-A enables multiple applications with various level of QoS (such as voice call and FTP downloading or video conference) running simultaneously. Clearly, voice or video calls requires lower delay jitter (i.e., fluctuation of packet delay) than FTP downloading to satisfy users with quality of connection. On the other hand, FTP downloading requires higher throughput and lower packet loss rate to minimize time of file download. To enable such various levels or quality requirements, LTE-A enables to define several various bearers with specific requirements of each one. To distinguish individual requirements, so called QoS Class Identifier (QCI) is introduced. The QCI defines nine classes according to a set of four transmission parameters as shown in table.

First, it indicates whether a bit rate is guaranteed (GBR - Guaranteed Bit rate) or not (Non-GBR). For GBR, a fixed amount of radio resources is permanently assigned to a service and it is not necessary to apply for these resources continuously. The amount of radio resources is set at the beginning of the connection and it corresponds to the maximum expected bit rate required by the given service. In case of Non-GBR, no resources are permanently reserved to the service. The amount of resources depends on the actual requirements of the service and amount of available resources in the network. Therefore, this type of services does not guarantee any bit rate.

The second important parameter defines priority of packets. This parameter indicates priority in case of processing. For example, if a node is congested, packets with higher priority are scheduled before packets with lower priority.

Next parameter is denoted as packet delay budget and represents maximum packet delay targeted by the given QCI.

The last parameter, packet error loss rate, is related to frequency of loosing packet during transmission. It represents amount of lost packets or packets received with an error that does not enable its further processing.

Service classes in LTE-A
QCI | GBR / Non-GBR | Priority | Packet delay budget | Packet error loss rate | Example of service
1 | GBR | 2 | 100 | 10-2 | Voice call (conversation)
2 | GBR | 4 | 150 | 10-3 | Video call (conversation)
3 | GBR | 5 | 300 | 10-6 | Streamed video (non-conversation)
4 | GBR | 3 | 50 | 10-3 | Real-time gaming
5 | Non-GBR | 1 | 100 | 10-6 | Signaling
6 | Non-GBR | 7 | 100 | 10-3 | Voice, video (live streaming)
7 | Non-GBR | 6 | 300 | 10-6 | Video (buffered streaming)
8 | Non-GBR | 8 | 300 | 10-6 | WWW, FTP, email, messaging
9 | Non-GBR | 9 | 300 | 10-6 | Like QCI 8, but with lower priority