CE Congestion can happens for UL (Uplink) and DL (Downlink), so first thing is to verify if CE Congestion is experienced in the UL or DL.
There are some suggestions to easy CE Congestion.
For example, for ‘UL CE Congestion’ you can disable 2ms TTI (duration of a transmission on the radio link) for HSUPA service.
Of course this will impact latency, throughput (with 2ms TTI we can respond faster to RF conditions).
Also: for ‘2 ms TTI’ it is consumed 8 CE (transmitted 160 kbps), and for ‘10 ms TTI’ it is consumed only 1 CE (but transmitted only 32 kbps).
Another option, if the number of R99 users are small, you can also disable 384kbps RABs (SF8) in RNC, and you’ll also get an improved ‘UL CE Utilization’.