What is the difference between QCI and ARP And when qci and arp are used?

Question

I have a question concerning QoS management in LTE: there are two parameters for an EPC bearer: QCI (QoS class identifier that resumes a set of parameters(priority, packet delay, packet error rate…) and ARP (Allocation and retention priority) that defines the priority of a bearer. My question is : what is the difference between the QCI priority and the ARP priority ?

Answer 1

On behalf of Bart -

QCI priority in allocating resources for service per its type, where ARP is priority for allocating the bearer.

In case the eNB is close to overloaded and there is a request from UE to establish data bearer for WWW service and VoIP then obviously the VoIP will have higher priority then eNB will probably establish only the VoIP bearer.

Or in other words, the ARP is used to kick lower priority bearers in case of overload.

Answer 2

That means you are looking the difference between QCI priority and ARP priority only -

Sort answer is both check the following cases -

1) QCI Priority refers to priority in terms of resource allocation for a specific service i.e. in case where the UE is running concurrently VoIP (higher QCI priority) session and browsing WWW (lower QCI priority), the resources are assigned firstly to packets of VoIP and then to WWW (and e.g. if we don’t have in the particular TTI resources to assign both packets, WWW need to wait and VoIP goes through).

2) ARP priority refers to priority in terms of allocation of a service / bearer, i.e. if the eNB is highly loaded and a UE would like to setup VoIP (higher ARP priority) and WWW (lower ARP priority), the eNB would typically set only VoIP session, in order not to get overloaded. Or in other case if it is already overloaded it would kick off (retent) the bearers / services with lower ARP priorities.

Comments

qci is used at ue side and ARP is used at eNB side is it correct?

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No thats not true. QCI is QoS Class Identifier and ARP is Allocation Retention Priority. Both serves the different purpose.