Sunday, 9 September 2007

ROHC, compressing IP headers over air interface

In an All-IP network, when IP packets are transmitted over the air, it would make more sense to strip down the headers as headers could be as big as the data being transmitted and these headers are overhead wasting the precious air resource. To help compress these headers, RObust Header Compression was standardised. Infact ROHC is not the only header compression scheme and i will post a bit more information in my future posts on which scehemes are available and why ROHC is used.

The diagram above shows the basic ROHC principle. It shows that ROHC compresseor is used before the data is sent over the air and decompressor at the receiving end adds the uncompressed headers back to the received packets. As expected, ROHC only works if both the ends have ROHC protocol.


A typical header compression is shown in the diagram above.
More information is available at the 3G4G website.

2 comments:

Peter J. Cranstone said...

It makes perfect sense to compress the headers. Especially in a mobile environment.

We do it without using a proprietary protocol.

We can compress and encrypt our headers inside the current HTTP protocol.

All that is required is a browser plug-in at one end and a server module at the other e.g. mod_mobile

Cheers,

Peter

Anonymous said...

Hi Zahid,

Can we provide some info on ROHC feedback channel? how it is configured?