August 2006
doc.: IEEE 802.22-06/0156r1
Superframe Structure
IEEE P802.22 Wireless RANs
Date: 2006-08-16
Authors:
Name
Company Address
Phone
email
Carlos Cordeiro
Philips
USA
914-945-6091
Monisha Ghosh
Philips
USA
914-945-6415
Carlos.Cordeiro@philip
s.com
Monisha.Ghosh@philip
s.com
Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in
this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE
Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit
others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the
statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to
patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard
is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair
Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being
developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].
>
Submission
Slide 1
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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
Submission
Slide 2
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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 802.22 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)
Submission
Slide 3
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
Superframe Structure: the General Case
– Capacity as
needed (up to
subscriber)
– Product
differentiation
– Controllable
by BS, etc.
...
Superframe n-1
Preamble
Frequency
• The MAC can
simultaneously
support single
channel and
multi-channel
CPEs
SCH
AW
Superframe n
frame 0
frame 1
Unit Channel
Preamble SCH AW
t-1
Unit Channel
Preamble SCH AW
t
Unit Channel
Preamble SCH AW
t+1
Frame
0
Frame
1
...
Frame
m
...
Superframe n+1
...
Preamble SCH
Frame
0
Preamble SCH
Frame
0
Preamble SCH
Frame
0
Time
frame m
Frame
2
Frame
1
Frame
2
...
Frame
2
Time
Submission
Slide 4
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
Superframe Structure: the Single Channel
case
• If only a single
channel is used,
the superframe
is transmitted
on that channel
only
...
Superframe n-1
Preamble
Superframe n
frame 0
SCH
...
Superframe n+1
frame 1
...
Time
frame m
• Plus, this allows
for future
extensions
Frequency
– No added
complexity
Unit Channel
Preamble SCH
t
Frame
0
Frame
1
...
Frame
n
Preamble SCH
Frame
0
Frame
1
Frame
2
...
Time
Submission
Slide 5
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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%!!!
Submission
Slide 6
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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
Submission
Slide 7
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
Appendix
Impact of the Superframe Structure on the
current Draft 0.1
Submission
Slide 8
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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)
Submission
Slide 9
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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. 6-282) 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. 6-207) 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
Submission
Slide 10
Carlos Cordeiro, Philips
August 2006
doc.: IEEE 802.22-06/0156r1
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, 6.8.21, 6.8.22, 6.8.25, 6.13.6, 6.15, 6.16,
6.21.1.7, 6.21.2, 6.21.3, 6.21.4, 6.21.5
• 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
Submission
Slide 11
Carlos Cordeiro, Philips