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[STDS-802-16] RE[STDS-802-16]FW: IEEE 802.16e Backward Compatibility



Can anyone respond to this?

Thanks in advance.

Brian

-----Original Message-----
From: Kaveh Ghaboosi [mailto:Kavehg@ee.oulu.fi] 
Sent: Tuesday, October 23, 2007 6:42 AM
To: Kiernan, Brian G
Subject: IEEE 802.16e Backward Compatibility

Dear Dr Brian Kiernan,

Hello!

I am Kaveh Ghaboosi, PhD student of Centre for Wireless Communications, 
University of Oulu, Finland.

Regarding the amendment 802.16e, I have a question that I believe that 
you are the only one from whom I can ask my question.

As it has been mentioned in the IEEE 802.16e document:

"This document provides enhancements to IEEE Std 802.16-2004 to support 
subscriber stations moving at vehicular speeds and thereby specifies a 
system for combined fixed and mobile broadband wireless access. This 
standard will increase the market for broadband wireless access 
solutions by taking advantage of the inherent mobility of wireless
media."

Based on my understanding, there should be a backward compatibility for 
the 802.16e with respect to IEEE 802.16-2004. Therefore, when the Base 
Station (BS) in Point-to-Multi-Point (PMP) scenario sends the Frame 
Control Header (FCH) which includes Downlink Frame Prefix (DLFP), all 
types of Subscriber Stations (SSs) and Mobile Stations (MSs) should be 
easily able to receive and successfully decode the delivered DLFP.

On the other hand, I can see that for the legacy IEEE 802.16-2004 in 
page 452 Table 225 the OFDM Downlink Frame Prefix Format is a bit 
different from that of IEEE 802.16e-2005 in page 326 Table 225. 
Basically, we can see that after the first so-called "reserved" field (4

bits after the "Configuration_Change_Count" in 802.16-2004 the FOR loops

starts while, in IEEE 802.16e-2005 after the aforementioned "reserved" 
field, the "Rate_ID", then another "reserved" field, then "length" 
fields are coming.

Now my question is: If we assume that we have both 802.16d and 802.16e 
compatible SSs/MSs in our network, whether the legacy 802.16-2004 SSs 
will be able to easily decode the received DLFP based on the 802.16e 
format or not? In other words, I would like to know whether the legacy 
802.16-2004 SSs will be able to decode and successfully received the 
DLFPs based on 802.16e or not? Also, I am wondering how the recommended 
format for the new DLFP for 802.16e has been derived and concluded to be

incorporated into the amendment. Shall I take into account some 
pre-assumptions or not? Is there any hint regarding how the extra 
fields/sub-fields should be included into the 802.16 while keeping the 
backward compatibility?

Dear Dr Kiernan, I am looking forward to hearing from you and I would 
like to thank you for your kind support and concern.

Kind Regards,
Kaveh