Group call voice not clear issue analysis report
Issue Description
For voice not clear issue, after test group call & Video call of different sites, from test result, we got the situation are:
1. When group call with 2 hops VSAT sites ( Site10,site11,site12,site13), sometimes the voice quality is not very clear.
2. When group call with other sites (Site1,site2,site3,site4) voice quality is good.
3. When video call with all sites, voice quality is good.
Handling Process
We do ping test from core network to 2 hops VSAT site, find out the latency and jitter is not stable, beyond the requirement of eLTE system.
1. Average latency is 607.9ms (1215.9ms/2), max latency is 883.7ms (1767ms/2).
Average jitter is 91ms.
2. From statistics of ping result, jitter higher than 60ms (eLTE system requirement) times are 247. When jitter higher than 60ms, eNB can’t detect the right data packet will cause packet loss.
3. Why video call voice quality is better than group call voice quality?
Because group voice call have higher real-time requirement, so group voice call data packet sending time is shortly than video call, and jitter affected group voice call more than video call.
4. eLTE system transmission requirement of single way:
Latency: <600ms
Jitter:<60ms
Packet loss:<0.01%
Solution
Because now VSAT transmission requirement is beyond eLTE system, we need to solve the latency and jitter to fulfil the requirement.
1. Using FO from VSAT HUB from city A to City B(eLTE core network) to reduce the latency and jitter.
2. Move VSAT HUB to city B(eLTE core network), so eLTE core network to other VSAT sites will reduce to 1 hop, this also can get the better latency and jitter.
Source: support.huawei.com
