1. On-demand EOBS for hidden incumbent reporting
June 2006
doc.: IEEE yy/xxxxr0
June 2006
On-demand EOBS for hidden incumbent reporting
IEEE P Wireless RANs Date:
Authors:
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Ang Chee Wei, Institute for Infocomm Research
Ang Chee Wei, Institute for Infocomm Research

2. June 2006
doc.: IEEE yy/xxxxr0
June 2006
Abstract
We propose an extension to the EOBS (Explicit Out-Band Signaling) scheme so that the out-band signaling is turned on only upon occurrence of the hidden incumbent situation.
Ang Chee Wei, Institute for Infocomm Research
Ang Chee Wei, Institute for Infocomm Research

3. Content Overview of the hidden incumbent situation
June 2006
Content
Overview of the hidden incumbent situation
Overview of the EOBS scheme
On-demand EOBS
Calculation on signaling overhead saving
Ang Chee Wei, Institute for Infocomm Research

4. Overview of the hidden incumbent situation (1/2)
June 2006
Overview of the hidden incumbent situation (1/2)
CPE Rx
Affected CPEs (interfered by incumbent transmission) No
interference to
incumbent
receivers
BS/CPE Rx
BS/CPE Sensing
BS Tx
Incumbent Tx
Incumbent Rx (incumbent receivers are located inside this contour)
Incumbent Rx
Normal detection region
Incumbent receivers are not interfered by BS
CPEs in the dot-shaded region are interfered by the incumbent transmission
BS cannot detect the incumbent transmission directly
CPEs in the slash-shaded region are able to detect and report the incumbent transmission
Ang Chee Wei, Institute for Infocomm Research

5. Overview of the hidden incumbent situation (2/2)
June 2006
Overview of the hidden incumbent situation (2/2)
CPE Rx
Incumbent receivers interfered by BS
Interference to
incumbent
receivers
Affected CPEs
BS/CPE Rx
BS Sensing
BS Tx
Incumbent Tx
Incumbent Rx (incumbent receivers are located inside this contour)
Incumbent Rx
Normal detection region
Incumbent receivers in horizontal-line-shaded region are interfered by BS
CPEs in the slash-shaded region are able to detect and report the incumbent transmission, but if this region is small as shown there might not be any CPE in this region, and the incumbent receivers continue to be interfered by the BS
Ang Chee Wei, Institute for Infocomm Research

6. Overview of the EOBS scheme
June 2006
Overview of the EOBS scheme
BS to transmit control messages in several out-of-operating-bands (“out-bands”) periodically:
When a CPE finds that it loses synchronization with the BS, and that it sensed an incumbent transmission (“affected CPE”), it looks for the out-band broadcasts to gain synchronization and then send the report
The EOBS proposal defines these functionalities:
Searching and synchronizing to an out-band channel upon hidden incumbent detection
Method of acquiring uplink resource for sending report, e.g. pre-assigned US resource during network entry, or by contention
Report format
Ang Chee Wei, Institute for Infocomm Research

7. June 2006
On-Demand EOBS
To reduce the signaling overhead of periodic transmission of out-band broadcasts, we propose to turn on EOBS only on-demand
The BS is signaled by the affected CPEs to turn on the out-band broadcasts (EOBS) in this way:
The affected CPEs send out a special tone in one of the unused channels (list as specified by BS)
The special tone comprises of a set of sub-carriers turned on as specified by the BS
The BS picks up this signal during its out-of-band sensing. Upon detecting that it is the special tone, the BS turns on EOBS. EOBS takes over from here
The affected CPEs will switch off after a timeout if they do not hear the EOBS broadcast
EOBS is switched off after BS makes decision in response to the report
If there is no unused channel, the tone is sent in-band. The BS picks up the signal during in-band sensing. In this case EOBS is not turned on, the BS has to make decision without detail report
Ang Chee Wei, Institute for Infocomm Research

8. On-demand EOBS (at the CPE)
June 2006
On-demand EOBS (at the CPE)
Ang Chee Wei, Institute for Infocomm Research

9. On-demand EOBS (at the BS)
June 2006
On-demand EOBS (at the BS)
Ang Chee Wei, Institute for Infocomm Research

10. Calculation on signaling overhead saving
June 2006
Calculation on signaling overhead saving
Number of candidate channels = x
Mean arrival rate of a hidden incumbent = a
Broadcast message time length = c
Inter-EOBS broadcast time = s
Average tone duration before EOBS is turned on = b
Average total signaling time from arrival of an hidden incumbent to transmission of report for EOBS and OD-EOBS = tEOBS, tOD-EOBS
Ang Chee Wei, Institute for Infocomm Research

11. Calculation on signaling overhead saving
June 2006
Calculation on signaling overhead saving
If x = 3, c = 10ms, s = 1s, a = 1/day, b = 1s, overhead_saving = 99.96%
Ang Chee Wei, Institute for Infocomm Research

12. June 2006
Tone design
1 channel
Each WRAN uses a different set of sub-carriers within the channel to represent the special tone.
The CPEs and BS within the same WRAN can identify this special tone. The BS shall identify his signal and make decision to turn on our-of-band broadcast.
Neighboring BSs that detect this signal shall ignore it.
Ang Chee Wei, Institute for Infocomm Research