Doc.: IEEE 802.22-07/0403r0 Submission August 2007 Wendong Hu, STMicroelectronicsSlide 1 Impact of Directional Antenna at CPEs on Coexistence Beaconing

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.

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August 2007


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


Slide 3

doc.: IEEE 802.22-07/0403r0

Submission

Directional Antenna at the CPE

WRAN1

CPE1 BS1

August 2007


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


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


Slide 6

doc.: IEEE 802.22-07/0403r0

Submission


WRAN2 WRAN1

BS1BS2 CPE1CPE2

Non face-to-face neighbor-cell CPEs

August 2007


Slide 7

doc.: IEEE 802.22-07/0403r0

Submission


WRAN2 WRAN1

BS1BS2

CPE1

CPE2

No neighbor-cell CPE

August 2007


Slide 8

doc.: IEEE 802.22-07/0403r0

Submission


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


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


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


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


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


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


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


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

Documents

Doc.: IEEE 802.22-07/0403r0 Submission August 2007 Wendong Hu, STMicroelectronicsSlide 1 Impact of Directional Antenna at CPEs on Coexistence Beaconing