T314 and T315 Settings in NSN

[Syed Fahad]

I Recently implemented RRC Re- establishment feature in One of the RNC's and adjusted the T314 for VOICE and T315 for PS Services. My Question is why there is a different in Range of the values for these two timers. Like for T314 the value is from 0 - 20 seconds, but for T315 the value can be set from 0 to 1800 seconds!!!. Can any one explain, if the working principle for both timers is the same why T315 is usually set higher than T314.

[tsiz]

Since T315 is for PS services,it is not going to be perceived by the end user that much. Hence the big range in terms of T315 and the HsDschRclostT timer. We cannot have the same range for CS services as the end user will have bad call perception. I hope this answers your question.

[Syed Fahad]

Many Thanks for the logical explanation

[FrankPintor]

Some further info: T314 can take on one of the values (0, 2, 4, 6, 8, 12, 16, 20) seconds, while T315 can be one of (0,10, 30, 60, 180, 600, 1200, 1800) seconds. It's not a good idea to set a large value for T314, since this will degrade the user experience, i.e. the user will hang up rather than wait for the UE to re-establish the call.

If NSN offer network-initiated call re-establishment, this might be more effective: this is based on evaluating the uplink signal at the network, and a large proportion of dropped calls in 3G are due to uplink failure. There are also no 3GPP restrictions on the timers controlling network-initiated call re-establishment.