Byte-alignment

["Lars-Erik Jonsson" <lars-erik.jonsson@ericsson.com>]

Hi all ROHC-ers!

Discussion of technical issues on this list is of fundamental importance to get
results in the WG. I will therefore start with a discussion about the
byte-alignment issue and I hope we can clear this out easily.

The question is whether there is any reason to design a robust header
compression framework that can support non-byte-aligned versions of the scheme.
I do not think so. All link-layers I have seen are byte-aligned and that is also
preferrable from an implementation point of view.

This question is important because the answer gives different approaches to the
problem.
1) When designing a non-byte-aligned scheme, the objective is to make all fields
as small as possible on a bit-level.
2) For byte-aligned schemes the objective is instead to squeeze as much
information as possible into 1, 2 or several bytes. Then the smallest possible
header size must always be used.

We MUST always have versions of the scheme that are designed byte-aligned. A
non-byte-aligned scheme may be instantiated to byte-alignment but will not make
use of all bits in an optimal way.

I think it is important to clarify that (and if) we are only considering
byte-aligned solutions. Some mechanisms for non-byte-aligned solutions will not
be usable at all in a byte-aligned scheme and we could then ignore such
mechanisms when discussing solutions.

Regards!
/Lars-Erik


--------------------------------------------------------------
Lars-Erik Jonsson, M.Sc. - Ericsson Research
AWARE - Advanced Wireless Algorithm Research at Erisoft
Box 920, S-971 28 Luleå, Sweden
E-mail: lars-erik.jonsson@ericsson.com
Phone: +46 920 20 21 07
Mobile: +46 70 554 82 71
Fax: +46 920 20 20 99
Home: +46 920 999 57