What is ARP Priority Level in LTE?
In LTE, the ARP (Allocation and Retention Priority) priority level plays a central role in determining the importance of a bearer when the network is under resource constraints. Let me explain this clearly so you can understand how it works and where it fits into LTE’s QoS (Quality of Service) handling.
The ARP priority level is a numeric value ranging from 1 to 15, where:
- 1 indicates the highest priority
- 15 indicates the lowest priority
So, if you’re wondering how the network decides which bearer request to accept or reject when the radio resources are tight, this priority level becomes the deciding factor. The lower the number, the more “important” the bearer is considered by the network.
Why Does ARP Priority Matter?
Imagine a scenario where two new bearers are requested at the same time, but only one can be admitted due to limited resources. Now, the eNodeB will refer to the ARP priority level. If one bearer has a priority level of 2 and the other has 9, the bearer with priority 2 gets preference for resource allocation.
It’s important to note here that the ARP priority level doesn’t influence packet delay, jitter, or throughput once the bearer is active — that’s the job of the QCI (QoS Class Identifier). ARP only matters at the time of bearer establishment or modification.
Sample Use Cases Based on ARP Priority
| Service | ARP Priority Level |
|---|---|
| Emergency VoLTE Call | 1 |
| Online Gaming | 5 |
| Video Streaming | 8 |
| Email Sync or Background Apps | 13 |
You’ll usually find these ARP levels configured in the PCRF (Policy and Charging Rules Function) and passed to the MME when setting up bearers. As we discussed earlier when exploring ARP overall, the priority level is used together with pre-emption capability and pre-emption vulnerability to make decisions during congestion.
In practice, when you’re optimizing an LTE network, you want to ensure that essential services like emergency calls or control-plane messages are always given higher ARP priority, so they are never dropped or delayed during congestion.