Please see the senarios as follows;
A EDGE cell, UE with EGPRS Multislotclass 10 and MCS9 supported. Deep analysis of the UE logs clearly shows that, during upload and download, the RLC/MAC Data Block Format Header Type is not maintained as type 1. Which means that the data rate is poor! Would you say, it is an issue on the PCU or the UE? I beleive it can not be the UE as I have tried with few other reference UE’s and noticed the same behaviour.
Refer: 3GPP TS 44.060
EGPRS Uplink/Doenlink RLC/MAC header;
Header type 1: header for MCS-7, MCS-8 and MCS-9
Header type 2: header for MCS-6 and MCS-5
Header type 3: header for MCS-4, MCS-3, MCS-2 and MCS-1