VoLTE checklist

Had enough of CSFB call set up delays, delays in returning to LTE after voice call termination, additional signalling due to routing/location/tracking area updates?

Time to deploy VoLTE!

Here is my checklist to get things started..

1. An IMS network

2. UEs that support VoLTE

3. Support for QCI 1 (voice) and 5 (IMS signalling)

4. Support of QoS on your LTE network to prioritise QCI 1 & 5 and pre-empt other QCIs if needed

5. Semi-persistent scheduling so you don't run out of PDCCH capacity

6. Support for RoHC

7. A dropped call rate on LTE equal or better than the CS dropped call rate on the legacy network

8. Support for RRC Re-establishment (intra & inter eNodeB) to help with the above

10. Support for TTI bundling to improve cell edge performance

11. If your LTE coverage is not as good as the legacy network then SRVCC support to handover calls from LTE VoLTE to the legacy CS domain

12. Upgrade legacy MSCs to connect to IMS

13. Upgrade legacy MSCs to connect to MME via Sv interface

14. UE battery life in LTE equal or better than 3G

Easy :)

4GEE bandwidth now @ 20MHz

Back in October when EE launched their 4G network I wrote a post on their spectrum usage at the time (here). As recently announced by EE themselves they have now manage to re-farm another 10MHz block from their 1800MHz spectrum and thus offer LTE at the maximum 3GPP rel8 bandwidth of 20MHz.

As can be seen from the SIB19 extract below their new 20MHz EARFCN is 1667. This effectively extends the original 1617 EARFCN by 10MHz to the right of the 1800MHz spectrum allocation.

By defining both carriers in SIB19 they don't need to constantly update their 3G network as the 20MHz roll-out continues, as UEs will scan both centre frequencies and pick the one available to reselect to.

From a device perspective all LTE capable UEs must support 20MHz bandwidth so they all take advantage of the additional capacity.

Next step for EE is 3GPP rel10 carrier aggregation, which they announced they are looking into and will take advantage of their additional spectrum assets in the 800MHz and 2600MHz bands.