July 2006

Baowei Ji, Samsung

Slide 1

doc.: IEEE 802.22-06/0121r1

Submission

Channel Sensing Based on Self-Signal Suppression (SSS)

IEEE P802.22 Wireless RANs Date: 2006-07-19

Name Company Address Phone email Baowei Ji Samsung Telecom

America USA +1-972-761-7167 Baowei.ji@samsung.com

Yinong Ding Samsung Telecom America USA +1-972-761-7975 yding@sta.samsung.com

David Mazzarese Samsung Electronics Co. Ltd. Korea +82 10 3279 5210 d.mazzarese@samsung.com

Authors:

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 patcom@iee.org.>

July 2006

Baowei Ji, Samsung

Slide 2

doc.: IEEE 802.22-06/0121r1

Submission

Abstract

A novel channel sensing scheme is proposed based on self-signal suppression/cancellation, which allows in-band channel sensing without the requirements for quiet periods. The optimized tradeoff could be achieved between spectral utilization and the reliability of in-band channel sensing by combining SSS-based channel sensing with on-demand scheduling of quiet periods or dynamic channel hopping.

July 2006

Baowei Ji, Samsung

Slide 3

doc.: IEEE 802.22-06/0121r1

Submission

Motivation• Traditional thinking on inband channel sensing: Requirement for

quiet period.– Periodically/opportunistically scheduling quiet periods– Dynamic frequency hopping.

• The proposal is based on self-signal suppression (SSS): – Detect the self signal– Cancel the self signal– Sense over the remaining signal

• No requirement for quiet period during regular operation (ideally).• Almost any sensing algorithm can be applied after self signal

suppression.

July 2006

Baowei Ji, Samsung

Slide 4

doc.: IEEE 802.22-06/0121r1

Submission

Illustration of SSS

Wireless Channel

Channel Estimation

Self-Signal Detection

Self-Signal Reconstruction

Channel Sensingover

the Remaining Signal

Received Signals

July 2006

Baowei Ji, Samsung

Slide 5

doc.: IEEE 802.22-06/0121r1

Submission

IU Protection

P1

P2

Self Signal

P1

Remaining Signal

Self Signal

No Interference Signal Interference Signal Emergence

P3IU Signal

IU Signal

P2

Before SSS After SSS Before SSS After SSS

P3

Suppression Residual Signal

Noise Floor

Zero Noise

July 2006

Baowei Ji, Samsung

Slide 6

doc.: IEEE 802.22-06/0121r1

Submission

OperationSignal Received

Self-Signal Detected

Data Integrity Check Passed?

Self-Signal Reconstruction

Self-Signal Suppression

Channel Sensing over the Remaining Signal

Maximum Trials Reached?

No

No

Channel Possibly Occupied

Yes

Channel management

Yes

Normal retransmission protocols

July 2006

Baowei Ji, Samsung

Slide 7

doc.: IEEE 802.22-06/0121r1

Submission

Feasibility/Complexity for Implementation

• Only two blocks are unique to SSS.– Self-signal reconstruction

– Self-signal cancellation

• The residual self signal level should be below the Incumbent User signal level (possibly below the noise floor).

• Self-signal could be removed completely in the baseband if the channel estimation is ideal.

July 2006

Baowei Ji, Samsung

Slide 8

doc.: IEEE 802.22-06/0121r1

Submission

Enhancements: Reliable Channel Estimation

Received Data

Channel EstimationBased on a Single

Frame

Accumulation/AveragingOver Multiple Frames

To ImproveChannel Estimation

Preamble Downlink Burst

The channel is assumed to be stable over multiple frames

FCH, DL-MAP, UL-MAP

Uplink Burst

Frame Frame

July 2006

Baowei Ji, Samsung

Slide 9

doc.: IEEE 802.22-06/0121r1

Submission

Other Enhancements• The BS can do channel sensing over all the UL

bursts.• A CPE can do channel sensing over other CPE’s DL

bursts, besides its owns, because any CPE has the capacity to use the whole channel. However, the CPE won’t require for retransmission of other CPEs’ data if signal detection fails.

• Both the BS and CPEs can do long-time channel sensing over the remaining signals of multiple frames in order to increase the reliability and accuracy of channel sensing.

July 2006

Baowei Ji, Samsung

Slide 10

doc.: IEEE 802.22-06/0121r1

Submission

Optimal Channel Sensing Scheme

SSS-based Channel Sensing(regular operation without any IU or other LE signals)

Quiet Time-based Channel Sensing(quiet time scheduling or DFH)

(on-demand feature)

Channel movingChannel is probably occupied.

Channel is clear.

Channel is occupied.

Having moved to a new channel .

July 2006

Baowei Ji, Samsung

Slide 11

doc.: IEEE 802.22-06/0121r1

Submission

Conclusions

• This method is in parallel with other in-band channel sensing methods that are based on quiet period or DFH.

• Advantages of uninterrupted channel estimation.• Advantages of uninterrupted self-signal

transmission.• The potential optimal method: SSS-based, plus on-

demand quiet-time scheduling and / or DFH.