[wi-sun rlmmwg] Changes to RLMM Annex in PHY Specification

[Benjamin A. Rolfe]

Ryota-san,
The current text is technically contradictory.  The first sentence 
"shall be set to 0" precludes generating a frame with FCS field set to 
1, thus  contradicts the sentence "It can also use 2-octet CRC, in which 
case, the FCS Type field is set to 1.". This is the problem identified 
by the commenter (me).  I had inferred the first sentence was correct, 
which from your explanation (if I understand correctly) was an incorrect 
conclusion.  I apologize for my confusion.
I propose the following to reflect that for RLMM  either 2-octet or 
4-octet FCD may be used:

"The FCS field in the PHR shall be set to 0 when the frame contains a 
4-octet FCS and shall be set to 1 when the frame contains a 2-octet FCS."

I hope that correctly reflects what you intended.

Regards
Ben

On 3/3/2016 9:17 PM, Ryota Yamada wrote:
> Dear Kunal-san,
>
> I will put my comments between lines below.
>
>
> On 2016/03/03 8:20, Kunal Shah wrote:
>> Dear RLMM WG and Yamada-san,
>>
>> PHYWG recently gone through the ballot process as part of the PHY
>> specification and some of the comments received as part of the RLMM
>> profile Annex.
>>
>> One of the comment is to change the support for FCS type sentence.
>>
>> Currently the RLMM Annex as part of the PHY specification includes,
>> "The FCS Type field (in the PHR) shall be set to 0 (4-octet CRC). It can
>> also use 2-octet CRC, in which case, the FCS Type field is set to 1.”
>>
>> Proposed change,
>> "The FCS Type field (in the PHR) shall be set to 1 (2-octet CRC).
>> Packets received with the FCS field set to 0 may be discarded.”
>
> In RLMM Profile, as a result of the discussion in RLMM WG, both 
> 2-octet FCS and 4-octet FCS can be supported. When PSDU size is no 
> more than 255 octets, some devices can use 2-octet FCS. On the other 
> hand, some other devices can choose to se 4-octet FCS in different 
> type of network defined in RLMM Profile. Therefore, the proposed 
> change is not acceptable.
>
>
>> Other editorial changes was proposed to change the sentence from, "This
>> normative annex specifies PHY requirements for the Wi-SUN RLMM
>> profile.”, to "This normative annex contains PHY requirements specific
>> to the Wi-­SUN RLMM profile.”
>
> This editorial change seems to be acceptable.
>
>
> Best regards,
> Ryota
>
>
>> I would like to ask the group if the above resolution is acceptable as
>> shown above. Please let me know of any comments or objections by 4th
>> March 10PM JST.
>>
>> Please let me know of any comments or questions.
>>
>> Regards,
>> Kunal Shah
>> PHYWG Chair
>>
>>
>