Robust Header Compression (ROHC) is used in mobile networks to make voice data packets smaller by compressing their headers. This helps reduce the load on radio resources, especially when there are limited physical resource blocks (PRBs).
ROHC also helps improve performance over radio links by minimizing packet loss, lowering delays, and increasing system capacity. Currently, ROHC is mainly applied to voice packets to ensure more efficient data transmission and better call quality under challenging network conditions.
How ROHC implement on Network?
Once VoLTE is deployed, network operators can control whether ROHC is active by using the CellAlgoSwitch.RohcSwitch parameter. ROHC supports various compression profiles designed for different data protocols. For voice services in LTE, two specific profiles are commonly used: 0x0001 and 0x0002. These profiles define how the headers of voice data packets are compressed to improve transmission efficiency and reduce radio resource usage.
The size of compressed voice packets using ROHC can vary depending on two main factors: the ROHC mode (such as U-Mode, O-Mode, or R-Mode) and how frequently the dynamic fields in the packet headers change. In optimal conditions, where changes are minimal and ROHC is operating efficiently, the header can be compressed down to as little as 1 byte. This significantly reduces the overall packet size, conserving PRBs (Physical Resource Blocks) and improving system capacity—especially important in voice-over-LTE (VoLTE) services.