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RE: [rohc] IR and IR-DYN not present in 5.6
Hi Lars-Erik,
The new text looks better (more consistent). I have only some minor
comments:
1) Last paragraph in 5.6.3. Suggest to change "The compressor must not
transit to the SO state until it has received an ACK for ...", to,
"The compressor must not send packet type 0 (i.e. must not transit
to the SO state) or 1 until it has received an ACK for ...".
This fixes the logic hole caused by the compressor staying in FO state
but sending type 1 packets.
2) Last paragraph in 5.6.5. Suggest same change as above.
3) Suggest to remove the first sentence (see below) from 5.6.3:
"Transition from Optimistic to Reliable mode is permitted only after
at least one packet has been correctly decompressed, which means that
at least the static part of the context is established. "
I have been thinking about various reasons behind this sentence. However,
I failed to see the difference between transition O->R and U->O (see 5.6.2),
w.r.t. when the decompressor can initiate the procedure. Have I missed
anything?
Br,
Zhigang
-----Original Message-----
From: EXT Lars-Erik Jonsson [mailto:lars-erik.jonsson@ericsson.com]
Sent: Wednesday, December 06, 2000 6:25 PM
To: rohc
Subject: [rohc] IR and IR-DYN not present in 5.6
Hi all!!
Since I wrote chapter 5.6 before the formats of IR and IR-DYN was defined to
carry the mode transition bits, those packets where NOT supported by the
text. The current specification provides the bits, but do not describe how
to use them. Therefore I have made the necessary modifications to include
also those packet types in the descriptions of how to use them. Note that
these modifications do not change the scheme, only clarifies missing parts.
New text and figures are provided below:
Cheers,
/L-E
5.6.3. From Optimistic to Reliable mode
[.......]
Compressor Decompressor
----------------------------------------------
| |
| ACK(R)/NACK(R) +-<-<-<-| D_TRANS = I
| +-<-<-<-<-<-<-<-+ |
C_TRANS = P |-<-<-<-+ |
C_MODE = R | |
|->->->-+ IR*/UOR-2(SN,R) |
| +->->->->->->->-+ |
|->-.. +->->->-| D_TRANS = P
|->-.. | D_MODE = R
| ACK(SN,R) +-<-<-<-|
| +-<-<-<-<-<-<-<-+ |
C_TRANS = D |-<-<-<-+ |
| |
|->->->-+ R-0*, R-1* |
| +->->->->->->->-+ |
| +->->->-| D_TRANS = D
| |
As long as the decompressor has not received an UOR-2, IR-DYN or IR packet
with the mode transition parameter set to R, it must stay in Optimistic
mode. The compressor must not transit to the SO state until it has received
an ACK for a UOR-2, IR-DYN or IR packet sent with the mode transition
parameter set to R. When the decompressor receives packet types 0 or 1,
after having ACKed an UOR-2, IR-DYN or IR packet, it sets D_TRANS to D.
5.6.5. From Reliable to Optimistic mode
[.......]
Compressor Decompressor
----------------------------------------------
| |
| ACK(O)/NACK(O) +-<-<-<-| D_TRANS = I
| +-<-<-<-<-<-<-<-+ |
C_TRANS = P |-<-<-<-+ |
C_MODE = O | |
|->->->-+ IR*/UOR-2(SN,O) |
| +->->->->->->->-+ |
|->-.. +->->->-| D_MODE = O
|->-.. |
| ACK(SN,O) +-<-<-<-|
| +-<-<-<-<-<-<-<-+ |
C_TRANS = D |-<-<-<-+ |
| |
|->->->-+ UO-0*, UO-1* |
| +->->->->->->->-+ |
| +->->->-| D_TRANS = D
| |
As long as the decompressor has not received an UOR-2, IR-DYN or IR packet
with the mode transition parameter set to O, it must stay in Reliable mode.
The compressor must not transit to the SO state until it has received an ACK
for a UOR-2, IR-DYN or IR packet sent with the mode transition parameter set
to O. When the decompressor receives packet types 0 or 1, after having ACKed
an UOR-2, IR-DYN or IR packet, it sets D_TRANS to D.
5.6.6. Transition to Unidirectional mode
[.......]
Compressor Decompressor
----------------------------------------------
| |
| ACK(U)/NACK(U) +-<-<-<-| D_TRANS = I
| +-<-<-<-<-<-<-<-+ |
C_TRANS = P |-<-<-<-+ |
C_MODE = U | |
|->->->-+ IR*/UOR-2(SN,U) |
| +->->->->->->->-+ |
|->-.. +->->->-|
|->-.. |
| ACK(SN,U) +-<-<-<-|
| +-<-<-<-<-<-<-<-+ |
C_TRANS = D |-<-<-<-+ |
| |
|->->->-+ UO-0*, UO-1* |
| +->->->->->->->-+ |
| +->->->-| D_TRANS = D, D_MODE =
U
| |
After ACKing the first UOR-2(U), IR-DYN(U) or IR(U) packet, the decompressor
MUST continue to send feedback with the Mode parameter set to U until it
receives packet types 0 or 1.
--------------------------------------------------------------
Lars-Erik Jonsson, M.Sc.
Wireless IP Optimizations
AWARE - Advanced Wireless Algorithm Research at Erisoft
Ericsson Research, Corporate Unit
Box 920, S-971 28 Luleå, Sweden
E-mail: lars-erik.jonsson@ericsson.com
Phone: +46 920 20 21 07
Fax: +46 920 20 20 99
Home: +46 920 999 57