1. [Considerations of SCH functions in IEEE 802.22b Systems]
September 2013
doc.: IEEE xx b
September 2013
[Considerations of SCH functions in IEEE b Systems]
IEEE P Wireless RANs Date:
Authors:
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Gwangzeen Ko, ETRI
Gwangzeen Ko, ETRI

2. September 2013
doc.: IEEE xx b
September 2013
Abstracts
In this document, we investigate advantage and disadvantage of SCH employment in IEEE b Systems
Gwangzeen Ko, ETRI
Gwangzeen Ko, ETRI

3. September 2013
IEEE SCH Overview
The IEEE standard defined SCH in order to support below functions
Frame allocation map  location of SCH during super-frame period
Super-frame number  SCH sequence control
CP  information of cyclic prefix factor
FCH encoding flag  FCH PHY encoding mode notice
Self-coexistence capability indicator  Self-coexistence method notice
MAC version
Quiet period control  To control QP properly, total 12 fields are defined
Gwangzeen Ko, ETRI

4. September 2013
IEEE SCH Overview
The IEEE standard defined SCH in order to support below functions(continue)
SCW control  To exchange CBP packet, total 3 fields are defined
DS/US Split  To align the DS/US split boundary between interfered BSs, if this split information not matched between BSs, there are some additional interference under overlapped area, total 3 fields are defined
Incumbent detection reporting inhibit timer inhibit reporting of CPE incumbent detection during certain time duration
HCS
Padding bits
Gwangzeen Ko, ETRI

5. September 2013
IEEE SCH Overview
As a conclusion, SCH, defined in the IEEE ,supports many features for both Frame control and Coexistence mechanism between BSs
Gwangzeen Ko, ETRI

6. SCH features handover to FCH
September 2013
SCH features handover to FCH
In current IEEE b WG consider that SCH features moves from SCH to FCH as shown in [2]
This looks like there is no difference between SCH in [1] and FCH in [2]
However, there are some issues on this change as followed slides
For convenience later parts of this document, we will say that SCH and EFCH are represented SCH in [1] and FCH in [2], respectively
Gwangzeen Ko, ETRI

7. Super-frame Structure[1]
September 2013
Super-frame Structure[1]
Super frame Structure
Frame Structure
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8. Super-frame Structure[2]
September 2013
Super-frame Structure[2]
Super frame Structure
Frame Structure
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9. Structure comparison September 2013 Super frame Structure – SCH
Parameters are held during super-frame duration
Robust preamble
Extended Frame Structure – EFCH
Parameters can change during super-frame duration
Gwangzeen Ko, ETRI

10. Coexistence between BSs
September 2013
Coexistence between BSs
For coexistence between BSs
SCH and CBP take care of coexistence between BSs
If SCH is removed
EFCH, include both FCH and Extended FCH, can not replace with SCH
EFCH should be modified for coexistence functions
CBP should be modified, A CBP is composed of SCH+CBP IEs
It is required that L/S-CPE side coexistence functions
In order to coexistence mechanism working properly, more CBP should be exchanged because there is no SCH exchange
Less allocation of SCW  less overhead for coexistence mechanism
Gwangzeen Ko, ETRI

11. SCH Pros Cons Robust preamble for SCH
September 2013
SCH
Pros
Robust preamble for SCH
No change of coexistence part of existing standard
Coexistence mechanism
CBP
All SCH related parts
No additional coexistence functions in CPE
Less allocation of SCW  less overhead for coexistence mechanism
Cons
Parameter change duration larger than EFCH
Gwangzeen Ko, ETRI

12. EFCH Pros Cons Parameter change duration smaller than SCH
September 2013
EFCH
Pros
Parameter change duration smaller than SCH
Simple structure  if coexistence functions are not frequently required, all frames are the same format
Assuming 2 sec minimum sensing time, an EFCH transmits at most every 12.5 super-frames including channel switching time in hardware 700us
Cons
A lot of works for coexistence functions
Change of existing standard
New definition of CPE side
Gwangzeen Ko, ETRI

13. Conclusions SCH EFCH Less change for coexistence mechanism than EFCH
September 2013
Conclusions
SCH
Less change for coexistence mechanism than EFCH
Less transmission of CBP
Coexistence mechanisms between BSs are unique feature of other 802 standards. LTE deal with those functions in higher layer
EFCH
Faster reaction to situation change than SCH
Simpler frame structure than SCH
Required a lot of functions for coexistence
Gwangzeen Ko, ETRI

14. September 2013
References
[1] “IEEE P : Standard for Wireless Regional Area Networks Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV Bands”, Jul
[2] “802.22b General Frame,” b, July, 2013.
Gwangzeen Ko, ETRI