Doc.: IEEE 802.22-07/0403r0 Submission August 2007 Wendong Hu, STMicroelectronicsSlide 1 Impact of...
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Transcript of Doc.: IEEE 802.22-07/0403r0 Submission August 2007 Wendong Hu, STMicroelectronicsSlide 1 Impact of...
August 2007
Wendong Hu, STMicroelectronics
Slide 1
doc.: IEEE 802.22-07/0403r0
Submission
Impact of Directional Antenna at CPEs on Coexistence Beaconing Protocol
IEEE P802.22 Wireless RANs Date: 2007-08-16
Name Company Address Phone email
Wendong Hu STMicroelectronics 1060 East Brokaw Road, San Jose, CA 95131
408-467-8410 [email protected]
George Vlantis STMicroelectronics 1060 East Brokaw Road, San Jose, CA 95131 408-451-8109 [email protected]
Author:
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].
August 2007
Wendong Hu, STMicroelectronics
Slide 2
doc.: IEEE 802.22-07/0403r0
Submission
Abstract
• This presentation identifies the impacts of direction antenna employed at the CPEs on the CBP based inter-cell communications, by describing a number of coexistence scenarios where CBP is used.
• Issues such as Communication failure, “Hidden node” problem, SCW backoff slot size requirement (collision detection range) are discussed.
• Remedies are suggested as the conclusion.
August 2007
Wendong Hu, STMicroelectronics
Slide 3
doc.: IEEE 802.22-07/0403r0
Submission
Directional Antenna at the CPE
WRAN1
CPE1 BS1
August 2007
Wendong Hu, STMicroelectronics
Slide 4
doc.: IEEE 802.22-07/0403r0
Submission
Neighbor-cell CPE
• Neighbor-cell CPE: a CPE that is associated with a neighboring cell and located in the self-coexistence region (the overlapping region of multiple neighboring cells)
• For example, CPE1 and CPE2 are neighbor-cell of each other
WRAN2 WRAN1
BS1BS2
CPE1
CPE2
August 2007
Wendong Hu, STMicroelectronics
Slide 5
doc.: IEEE 802.22-07/0403r0
Submission
Self-coexistence Scenarios (1)
WRAN2 WRAN1
BS2BS1CPE1
CPE2
Face-to-face neighbor-cell CPEs
August 2007
Wendong Hu, STMicroelectronics
Slide 6
doc.: IEEE 802.22-07/0403r0
Submission
Self-coexistence Scenarios (2)
WRAN2 WRAN1
BS1BS2 CPE1CPE2
Non face-to-face neighbor-cell CPEs
August 2007
Wendong Hu, STMicroelectronics
Slide 7
doc.: IEEE 802.22-07/0403r0
Submission
Self-coexistence Scenarios (3)
WRAN2 WRAN1
BS1BS2
CPE1
CPE2
No neighbor-cell CPE
August 2007
Wendong Hu, STMicroelectronics
Slide 8
doc.: IEEE 802.22-07/0403r0
Submission
Self-coexistence Scenarios (4)
BS1
CPE2
WRAN3
BS3
CPE1CPE3
WRAN1
WRAN2
BS2
Hybrid - A mixture of the face-to-face CPE and the non-face-to-face
CPE cases
August 2007
Wendong Hu, STMicroelectronics
Slide 9
doc.: IEEE 802.22-07/0403r0
Submission
When neighbor-cell CPEs are face-to-face
• Beacons can be transmitted and received by the face-to-face neighbor-cell CPEs
• This is ONLY case where CBP packets transmitted by CPEs can be received by a neighboring cell.
WRAN2 WRAN1
BS2BS1CPE1
CPE2
August 2007
Wendong Hu, STMicroelectronics
Slide 10
doc.: IEEE 802.22-07/0403r0
Submission
When neighbor-cell CPEs are non face-to-face
• CBP packets transmitted by a CPE can not be received by any neighbor-cell CPE
• However, CBP packets transmitted by the Base-stations can be received by neighbor-cell CPEs and then conveyed to the target BSs
• This requires that the receiver equips with an omni-direction antenna (e.g. the sensing receiver) and shall be capable of decoding the CBP packets – still an open question.
WRAN2 WRAN1
BS1BS2 CPE1CPE2
August 2007
Wendong Hu, STMicroelectronics
Slide 11
doc.: IEEE 802.22-07/0403r0
Submission
CBP Communications Fail without a Neighbor-cell CPE (1)
WRAN2 WRAN1
BS1BS2
CPE1
CPE2
• Beacons from WRAN2 will never be received (therefore never be discovered) by WRAN1.
• Without knowing the existence of WRAN2, WRAN1 will interfere WRAN2’s operation (if channel is not symmetrical) and sensing, when, for example, operating co-channel with WRAN2.
• WRAN2 may decide to switch channel, which however may not be always possible.
August 2007
Wendong Hu, STMicroelectronics
Slide 12
doc.: IEEE 802.22-07/0403r0
Submission
CBP Communications Fail without a Neighbor-cell CPE (2)
WRAN2 WRAN1
BS1
CPE1
CPE2CPE3 BS2
WRAN3
BS3
CPE4
• WRAN1, WRAN2, and WRAN3 will not be able to synchronized for their quiet periods.
• Such situation becomes serious when the WRANs are on co-channel and/or on the 1st adjacent channels.
August 2007
Wendong Hu, STMicroelectronics
Slide 13
doc.: IEEE 802.22-07/0403r0
Submission
CSMA-based CBP doesn’t work well with the directional antenna
• CSMA needs omni-directional antenna for both transmission and reception, otherwise the neighbor nodes can not detect one another (the hidden node problem).
• CSMA/CA couldn’t help as the size of the CBP packet is too large compared to the contention window (SCW) – RTSs could likely collide as well.
BS1
CPE2
WRAN3
BS3
CPE1CPE3
WRAN1
WRAN2
BS2
August 2007
Wendong Hu, STMicroelectronics
Slide 14
doc.: IEEE 802.22-07/0403r0
Submission
BS-transmitted CBP requires large slot time for carrier sensing and collision detection
WRAN2
BS1BS2
CPE1
WRAN2
BS2
CPE2
WRAN1
BS-CPE Association
CBP Transmission
Carrier Sensing
For a BS-to-BS distance of 50km, one symbol duration is required for carrier sensing and collision detection.
August 2007
Wendong Hu, STMicroelectronics
Slide 15
doc.: IEEE 802.22-07/0403r0
Submission
Proposed Remedies
• The CPE in the cell-overlapping area should employ an Omni-directional antenna or multiple directional antennas for CBP transmission.
• Use one symbol duration as the backoff slot size for CSMA/CD .
WRAN2 WRAN1
BS1BS2
CPE1
CPE2