Re: [STDS-802-16] Incremental type BW request Clarification

From: Phillip Barber [mailto:pbarber@broadbandmobiletech.com]
Sent: Thursday, September 16, 2004 10:06 AM
To: STDS-802-16@listserv.ieee.org
Cc: Johnston, Dj
Subject: Re: [STDS-802-16] Incremental type BW request Clarification

See:

6.3.6 Bandwidth allocation and request mechanisms

6.3.6.1 Requests, page 114, line 44

Because the uplink burst profile can change dynamically, all requests for bandwidth shall be made in terms of the number of bytes needed [emphasis added] to carry the MAC header and payload, but not the PHY overhead. The Bandwidth Request message may be transmitted during any uplink allocation,except any initial ranging interval.

Thanks,
Phil

----- Original Message -----

From: Johnston, Dj

To: STDS-802-16@listserv.ieee.org

Sent: Thursday, September 16, 2004 11:11 AM

Subject: Re: [STDS-802-16] Incremental type BW request Clarification

This discussion has come up before. The units seem to be missing.

If we take the text to mean what it says, I.E. 'Bandwidth', then we can read 'SS requests 100' as meaning 'SS requests 100Hz'. Probably not what is intended.

DJ

From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org] On Behalf Of carl.eklund@NOKIA.COM
Sent: Thursday, September 16, 2004 5:43 AM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Incremental type BW request Clarification

Jung Je,

'perceived bandwidth needs of a connection' at the BS means 'the amount that the BS at that instant believes should be granted to a given connection'. Now lets look at your example:

SS requests 100

BS grants 70

The SS has two options:  A) steal some bandwidth and issue an aggregate request for 120; B) it can issue an incremental request of 90.

Now disregarding any timing issues due to process scheduling in the BS the two cases are differ in the following way

Peceived need at the BS  after the grant of 70 is 30. In case A) the BS overwrites 30 with 120; in case B) the BS makes the calculation 30+90= 120.

Now a fundamental property of the grant per SS scheme employed in 802.16 is that there is no guarantee that the SS uses the bandwidth as the BS intended it. This means that the perceptions at BS and SS can be different and situations occur where there are mismatches between the state information at the BS and the SS. Again let me stress that this is a design feature and not a bug in the protocol. Each vendor should design their scheduling algorithms in the SS and the BS, respectively, to recover from these mismatch situations.

BR Carl

-----Original Message-----
From: jungje.son@samsung.com [mailto:jungje.son@samsung.com]
Sent: 16 September, 2004 14:29
To: Eklund Carl (Nokia-NRC/Helsinki); STDS-802-16@listserv.ieee.org
Subject: RE: [STDS-802-16] Incremental type BW request Clarification

Carl,

Thanks for your response.

Then do you think “perceived bandwidth needs of a connection” means granted bandwidth for the connection

Otherwise do you think it may vary case by case?

My point was to clarify the rule of using incremental BW request message by SS and BS.

In my thought, BS should recognize the same size of requested bandwidth as requested.

Therefore, SS should know how much is the “perceived bandwidth”.

For example,

When SS have requested 100 for connection A and was granted 70.

And SS wants to request 120 (90 for new data and 30 for last unsent data).

My question is how SS denotes 120 at incremental BW request message and BS can recognize 120 as requested by incremental BW request message.

BR

Jung Je Son, PH.D.
Senior Engineer
Global Standards Strategy Team
Telecommunication R&D Center
SAMSUNG ELECTRONICS CO., LTD
Tel : +82-31-279-5098
Mobile : +82-16-9530-5098
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What Do You Want To Be? Plan, Do and See?

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From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org] On Behalf Of carl.eklund@NOKIA.COM
Sent: Thursday, September 16, 2004 7:45 PM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Incremental type BW request Clarification

Jung Je,

in my opinion there is no error in the sentence you quote in your mail and therefore it shouldn't be a corrigenda item. The 'perceived bandwidth needs of a connection' is not equivalent with the amount requested in the previous (aggregate) BW request message as the BS may choose to grant the the requested capacity in several chunks. Also as the scheduling algorithm in the BS unfortunately suffers from non-zero latency the perception of the BS can be different from the amount requested in the previous BW request message.

BR Carl

-----Original Message-----
From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org]On Behalf Of jungje.son@SAMSUNG.COM
Sent: 16 September, 2004 11:06
To: STDS-802-16@listserv.ieee.org
Subject: [STDS-802-16] Incremental type BW request Clarification

In current 802.16 2004 spec, page 144 line 50 says

“When the BS receives an incremental Bandwidth Request, it shall add the quantity of bandwidth requested to its current perception of the bandwidth needs of the connection”.

How should I understand “perception of the bandwidth needs of the connection” ?

It is the same value with requested bandwidth by last BW request message of the connection from MSS?

Furthermore, such a thing is a corrigenda item?

Thanks,

Jung Je Son, PH.D.
Senior Engineer
Global Standards Strategy Team
Telecommunication R&D Center
SAMSUNG ELECTRONICS CO., LTD
Tel : +82-31-279-5098
Mobile : +82-16-9530-5098
--------------------------------------------------

What Do You Want To Be? Plan, Do and See?

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