1. IEEE P802.22 Wireless RANs Date: 2006-08-16
August 2006
doc.: IEEE yy/xxxxr0
August 2006
Superframe Structure
IEEE P Wireless RANs Date:
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Carlos Cordeiro, Philips
Carlos Cordeiro, Philips

2. August 2006
Introduction
The purpose of this presentation is to provide further clarification on the superframe structure adopted in the current Draft 0.1 spec
In this presentation we show that:
Superframe allows the support of a number of advanced features, NOT ONLY channel bonding
Superframe allows the standard to be future proof
Superframe can also be used for SINGLE CHANNEL only case
Superframe overhead is negligible
Carlos Cordeiro, Philips

3. August 2006
Superframe Structure
Superframes allow a number of advanced features to be implemented
For incumbent protection, so that quiet periods of overlapping networks can be synchronized
The self-coexistence mechanisms available in the current draft depend on it
The synchronization of overlapping networks depend on it
So, it is NOT all about channel bonding
A great deal of the current draft 0.1 spec relies on the superframe structure for a number of different things (please refer to the spec for more info)
Carlos Cordeiro, Philips

4. Superframe Structure: the General Case
August 2006
doc.: IEEE yy/xxxxr0
August 2006
Superframe Structure: the General Case
The MAC can simultaneously support single channel and multi-channel CPEs
Capacity as needed (up to subscriber)
Product differentiation
Controllable by BS, etc.
Carlos Cordeiro, Philips
Carlos Cordeiro, Philips

5. Superframe Structure: the Single Channel case
August 2006
Superframe Structure: the Single Channel case
If only a single channel is used, the superframe is transmitted on that channel only
No added complexity
Plus, this allows for future extensions
Carlos Cordeiro, Philips

6. Superframe Structure in Numbers
August 2006
doc.: IEEE yy/xxxxr0
August 2006
Superframe Structure in Numbers
Superframe size is fixed at 160ms
That is, a total of sixteen 10ms frames per superframe
Superframe structure consumes only 3 OFDM symbols for an entire superframe duration
Short preamble + long preamble + superframe header
If we consider the size of an OFDM symbol of about 373µs, this results in negligible overhead of less than 0.47% since there is no need to transmit the next frame’s preamble (the superframe preamble is enough)
Even if one still wants to transmit the frame preamble, the worst case overhead would still be limited by less than 0.70%!!!
Carlos Cordeiro, Philips
Carlos Cordeiro, Philips

7. August 2006
Conclusions
The superframe structure allows for a number of advanced features to be implemented
A number of mandatory schemes in draft 0.1 depend on it
We have shown that the superframe structure:
Allows the support of a number of advanced features, NOT ONLY channel bonding
Allows the standard to be future proof
Incurs negligible overhead of only 0.70%
Can also be used for the SINGLE CHANNEL only case
The superframe structure is currently mandatory
This way, the standard is made future proof and compatible with future amendments/enhancements
Carlos Cordeiro, Philips

8. Impact of the Superframe Structure on the current Draft 0.1
August 2006
Appendix
Impact of the Superframe Structure on the current Draft 0.1
Carlos Cordeiro, Philips

9. August 2006
Purpose
As mentioned at the beginning of this presentation, a number of features in the draft depend upon the superframe structure
The purpose of the next few slides is to provide further insight on and quantify the impact of the superframe structure on the entire specification
We mostly consider direct dependency, even though it is very likely that there exists some sections which have indirect dependency (this would require a more detailed and more time consuming analysis)
Carlos Cordeiro, Philips

10. August 2006
Some Statistics
A simple search for the string “SCH” in the draft returns with 108 hits
Obviously, this does not include a large number of figures and flowcharts that include the string “SCH”
It does not include also those sections of the draft that have an indirect dependency on the superframe structure
Hence, if we consider the main body of the draft (pp ) the string “SCH” is present in about 39% of the pages
This means, at the very least, once every 3 pages
If we consider the MAC section only (pp ) where it has the most impact, the string “SCH” appears in about 53.4% of the pages
That is, at least once every 2 pages
Carlos Cordeiro, Philips

11. Sections of the Draft that Depend on the Superframe Structure
August 2006
Sections of the Draft that Depend on the Superframe Structure
A simple analysis of the draft reveals that the following sections depend of the superframe structure
MAC
Sections: 6.3, 6.5.1, 6.6.1, 6.7, 6.8.1, , , , , 6.15, 6.16, , , , ,
The total number of pages correspond to about 100
PHY
Sections: 8.1.1, 8.1.2, 8.2, 8.3, 10.1
The total number of pages correspond to about 15
Other
Section: 10.1
The total number of pages correspond to about 3
Altogether, these sections correspond to, approximately:
42.6% of the total number of pages in the main body of the draft; and
49.8% of the total number pages in the MAC section alone
Carlos Cordeiro, Philips