Header compression and integrity check in Cplane

Hi Experts.

Some query from pdcp layer of 5G:

  1. Why header compression is not applied to Cplane data limited to Uplane only
  2. Why integrity check applicable to Cplane only?

Anyone have idea of above query

1 Like

The root cause is related to the role and function of header compression, which is used to reduce the overhead of the payload and improve the throughput. Thus it take the most advantages of the short payload. While Cplane traffic itself is the overhead the communication, which generally only takes a small fraction of one session traffic. Also compared to the voice short packet traffic, Cplane traffic’s payload may be a significant portion of its packet length.

Integrity check guarantee the correctness of Cplane traffic, which is the only mechanism for Cplane traffic terminated in RRC. But Uplane traffic has upper layer (transport layer for example) to make sure the payload correctness. Also AM/TM mode play a role here(need double check): according to my impression, AM (transparent mode) for Cplane while TM (transport mode : Retransmission is applied in the link layer) for Cplane.

Here I messed up AM/TM: AM is acknowledge mode, and TM is transmit mode.