Hi Biplab,
From: Biplab Sarkar
[mailto:bsarkar at starentnetworks.com]
Sent: Tuesday, September 04, 2007
6:08 PM
To: Gangadharan
G, TLS-Chennai
Cc: rohc at ietf.org
Subject: Re: [rohc] Doubt in W-LSB
Encoding
Gangadharan,
At the decompressor, the value of 'K' is the number of bits that can fit
in the particular ROHC packet. So given a ROHC packet, the value of 'K' is
fixed. The problem now melts down to find out which is the value in this range
of 2^K numbers that is really being transmitted.
At the compressor, the problem is to first find out what would be the optimal
value of 'K' that is good enough to carry the desired number of bits with a
particular value of reordering 'p'. So at the compressor once the value of 'K'
is chosen depending upon the number of bits to be sent, the value of 'p' also
gets set.
How to choose that optimal value of K?
Is it any of the below method?
(1) Actual no. of bits required to
represent the [Current value (v) – v_ref]
(2) The above value(1) round off to a nearer
possible that can be represented in the Rohc packet (4 for UO-0, 6 for UOR-2,
etc.)
(3) Any constant value (common to all v
values)
Thanks,
Gangadharan
Thanks
Biplab
On Tue, 2007-09-04 at 17:06 +0530, Gangadharan G,
TLS-Chennai wrote:
Hi All,
I am new to
the ROHC technology.
Please, can
anyone clarify my below doubt.
RFC 3905
Section 5.7 (page 75) states that,
SN: The
compressed RTP Sequence Number.
Compressed with W-LSB. The interpretation intervals, see section
4.5.1, are defined as follows:
p =
1
if bits(SN) <= 4
p = 2^(bits(SN)-5) - 1 if bits(SN) > 4
As stated
above, the value of P (constant integer of LSB encoding) is depends on
bits(SN).
Here, the
bits(SN) denote the no. of bits for the SN field in the ROHC packet.
But the
value of bits(SN) can be derived only from the value of K (output of the LSB
Encoding algorithm).
How the
Input value of the LSB Encoding (P) can depend on the Output value of the LSB
Encoding (K)?
Please
forgive me if I am ignorant on anything.
Thanks in
Advance,
Gangadharan
|
DISCLAIMER:
-----------------------------------------------------------------------------------------------------------------------
The contents of this e-mail and
any attachment(s) are confidential and intended for the named recipient(s)
only.
It shall not attach any liability
on the originator or HCL or its affiliates. Any views or opinions presented
in
this email are solely those of
the author and may not necessarily reflect the opinions of HCL or its
affiliates.
Any form of reproduction,
dissemination, copying, disclosure, modification, distribution and / or
publication of
this message without the prior
written consent of the author of this e-mail is strictly prohibited. If you
have
received this email in error
please delete it and notify the sender immediately. Before opening any mail
and
attachments please check them for
viruses and defect.
-----------------------------------------------------------------------------------------------------------------------
|
_______________________________________________
Rohc mailing list
Rohc at ietf.org
https://www1.ietf.org/mailman/listinfo/rohc