This section is only applicable to the lab application.
ROHC (Robust Header Compression) function is realized in the Enhanced Multi-flow Packet Application 1xEV-DO Lab Application. ROHC is the primary mechanism for VoIP with the purpose of compressing the header of VoIP packets down to an efficient level.
When IP technology is used for interactive voice conversations over cellular links, a big problem is the large header overhead. In 1xEV-DO system, speech data is carried by RTP, UDP and IP. The size of RTP header, UDP header, and IP header (IPv4) are 12 octets, 8 octets and 20 octets, respectively. A total of 40 octets, or 320 bits . However, in cdma2000 system, speech payload was encoded into 20 ms frames that contains 171 or 266 data bits (8k or 13k vocoder).This delivery model is quite inefficient as the header overhead is much larger than payload itself. ROHC can resolve this issue and compress the header to as low as 3 bytes .