Doc.: IEEE 802.15-07/758r2 TG3c Presentation LG Electronics & SiBEAM 18/July/2007 Slide 1 Project:...

18/July/2007

Slide 1

doc.: IEEE 802.15-07/758r2

TG3c Presentation LG Electronics & SiBEAM

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Submission Title: [Discussion on Coexistence Mechanism]Date Submitted: [9 July 2007]Source: [(alphabetical list) BeomJin (Paul) Jeon1, James P. K. Gilb2, Jeff Gilbert3, John Marshall4 YongHoon Kim5]Company [1,5LG Electronics Inc., 2,3,4SiBEAM, Inc.]Address [1,516 Woomyeon-Dong, Seocho-Gu, Seoul, Korea, 2,3,4555 N Mathilda Ave Ste 100, Sunnyvale, CA 94085]Voice: [1,5+82 2 526 4065, 2,3,4+1 408 245 3120], FAX: [], E-Mail: [1bjjeon at lge dot com, 2gilb at ieee dot org, 3jgilbert at sibeam dot com, 4jmarshall at sibeam dot com, 5yonghkim2002 at empal dot com]Re: []

Abstract: [Discussion topic on the purposes and methods of coexistence of multiple PHY systems in 60GHz band.]

Purpose: [To initiate open discussion on the optimal coexistence mechanism in mmWave]Notice: This document has been prepared to assist the IEEE P802.15. 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 acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

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Overview

• A view on coexistence– Principles of coexistence & related issues

• Coexistence Mechanism– Optimal coexistence mechanism discussion

• Concluding Remark

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Background• In the last meeting :

– 16 PHY Proposals were presented– Their channelizations, modulation schemes,

coverage and bit rate were different.– 8 of them declared, in the content, that they

would merge with other candidates .

• In 5 proposals :– Several coexistence mechanisms were proposed

but the targeting coexistence were slightly different.

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Levels of Coexistence MechanismCoexistence Coexistence

In theSame space

CoexistenceIn theSame Frequency Channel

CoexistenceIn theSame Piconet

BySimpleDetect andAvoid

Power Detect

Preamble Correlation

PHY Identifier in Preamble

Sending multiple beaconsfor each PHY

Usingadditional common PHY mode

BymmWave’sInherentDirectionality

f

BySharingSchedulingInformation

t

t

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The key principles for coexistence• What are the key features required for two

heterogeneous PHY systems to coexist?

• The human world case study :– mutual respect for territorial integrity– mutual non-aggression– non-interference in each other’s internal affairs– equality and mutual benefit– peaceful co-existence

The Five Principles of Peaceful Coexistence, “Panchsheel”, from the peace agreement between China and India in 1954

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Mutual respect for territorial integrity• What will be the territory in the wireless

world?– A territory is a defined area considered to be a possession of,

usually legally administered by, a person, organization, ….

– In the 802.15.3c world, the beacon coverage area of a certain network may be considered as a territory of it.

– Issue #1 : How to identify the territories of heterogeneous PHY networks.

– Issue #2 : Un-identical beacon coverage

– Issue #3 : Stations in the edge

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Mutual non-aggression• Fortunately, at this moment, there is no way to

attack any heterogeneous station which might have entered (or initiated a network) accidentally in the already occupied channel.– Issue #4 : Even with “Listen before configuration”

mechanism, in case of miss-configuration, how to detect the interference and who shall surrender the channel if it detects interference.

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non-interference in each other’s internal affairs

• Issue#5 : How to avoid interference– Just move to the other empty channel

sub issue #5-1 : Finite usable channels

– Or share the channel with the existing network by using empty time slot in TDMA mannersub issue #5-2 : How to share the scheduling information among heterogeneous stations

– Or just use the same channel hoping that the directivity of mmWave beam will minimize the interference. sub issue #5-3 : How to guarantee no-interference.- Beacons may be omni-directional - Depends on the locations of devices

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equality and mutual benefit• This means that it is not desirable to have

un-equality like below :“Devices using PHY ‘A’ can go without any coexistence measures but others must detect PHY ‘A’ network and avoid interference with it by all costs.”Or, “I have no coexistence measure at all. So, please avoid me if possible although I cannot avoid you” ( = “My car has no braking system.”)Issue #2 : The un-identical beacon coverageIssue #4 : Then who will surrender the channel

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Solution comparison (example)

Solution 1. Simple and no-interference but finite useable channel issue must be considered.Solution 2. If we can guarantee no-interference, it is optimal for mmWave.Solution 3. Coexist in the same piconet method is good for many coexistence issues except its complexity. Besides the complexity, from the application point of view, different PHY shares channel time, their real through put might not be served at its maximum and also there is no reason to share the superframe time in view of application.

In addition, un-identical beacon coverage issue must be addressed.

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Optimal coexistence mechanism for mmWave?• As simple as possible thinking of the frequency of interference

case. (How many mmWave communication application will be running in the same room and at the same time?)

• Different levels of sensitivity shall be taken into account. HD video streaming may be more sensitive to interference than file transfer. Slow file transfer may be tolerable but defects on the movie screen cannot be tolerated. (Users willingly wait for 2 hours downloading a cool movie file.)

• Making the best of 802.15.3c characteristics. We have coordinators and omni-directional beacons but our mmWave beams used for application data transfer are highly directional.

• A structure with high flexibility for optional usage and backward compatibility.

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Optimal Solution Discussions• Issue #1 : How to identify the territories

The coordinator may add some dedicated common codes ahead of the beacon preambles to identify its service area and sensitivity grade (for example, Video Streaming or File Transfer). By this common code, stations using even heterogeneous PHY can identify the service area and its sensitivity to interference and can choose to move to other empty channel or choose to stay but in very “cautious manner”.

PLCP Header BEACON PSDUCommon Codes for Sensitivity & Area

PHY Specific PLCP Preamble Portion

For our ownFor other PHYs only

Beacon Starting Time

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Optimal Solution Discussions• Issue #2 : Un-identical beacon coverage

The beacon coverage is enough to cover only its service area. And we can repeat only the “common codes for sensitivity & area” portion to make identical detection coverage regardless of beacon coverage.

PLCP PreamblePLCP Header BEACON PSDUCommon Codes for S&ACommon Codes for S&ACommon Codes for S&A

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Repetition of Code (example)

Barker13 Barker13

Barker13 Barker13 Barker13 Barker13

Walsh Length =2

Walsh Length =4

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Optimal Solution Discussions• Issue #3 : Station at the edge

The station can report its intolerable interference (i.e. channel condition) to its coordinator and persuade the coordinator to change its operating channel.But if the coordinator can secure it service area beyond its beacon coverage, the probability of this kind of problem can be reduced.

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Optimal Solution Discussions• Issue #4 : How to detect interference and Who will surrender

The coordinator can notify the interference to the interference source using “Alert Codes”. And the coordinator in the “cautious manner” will be listening to detect the interference (i.e. whether it causes interference or not), if it detects the interference, it can take adequate actions like below :- Reduce TX power- Reduce Data Rate (i.e. TX duty)- Stop transmitting and move to the other channel

PLCP Header BEACON PSDU

Common Codes for Alert

PHY Specific PLCP Preamble Portion

For our ownFor other PHYs only

Beacon Starting Time

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Optimal Solution Discussions• Issue #5 : How to avoid interference 1

If a station detect a high sensitivity network in a channel, it may choose to move to another empty channel. But the useable channel number is finite, so it may want to stay in the same channel. In that case, the omni-directional beacons may conflict with each other. So, for the omni-direction beacons of multiple PHYs, we may set up multiple narrow band in one channel and let them use these narrow band channels for their beacon signaling.

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Optimal Solution Discussion• Issue #5 : How to avoid interference 2

Further more, we can dedicate a certain narrow band channel (red) for the beacon of the most sensitive application. We can make the coordinators (yellow and green) of non sensitive application (like file transfer) always monitor the dedicated beacon channel (red) to detect interference to the sensitive application like HD video transmission.

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Optimal Solution Discussion

In 3 years, …

In ?? years, …

OR?

Not so many devices in a house.Couple of devices in one room.

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Flow Chart (Example)

Searching Channels

Power On

Your Coordinator is

Found?

YesAssociate with it!

No

Are thereany emptychannel?

If all useable Channels areoccupied then choose

most insensitive channel

Yes Go there andStart Piconet there!

No

Sensitivity levelis acceptable?

Yes

No

Can it be upgrade?

No Yes

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Flow Chart (Example)-Cont’

Lowestsensitivity level

is high?

Yes

Just select empty Beacon channel and start piconet there

No

Are thereany interference

Alert?

If all useable Channels areoccupied then choose

most insensitive channel

Yes Reduce TX Power orReduce date rate (or duty) orFind other channel to share!

Mysensitivity level

also is high?

You may use this channel but QoS cannot be guaranteed.

Yes

No

Start Piconet there butperiodically monitor the highest

priority beacon channel

No

Keep using it!

Mysensitivity level

is high?

Yes

No

Select Highest Priority Beacon channel and start piconet there

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Concluding Remark• We, together, would better develop the optimal

coexistence mechanism for our mmWave WPAN.– It should be able to answer the known issues.– It should be as simple as possible with respect to the issue’s

severity.– The sensitivity of the each application should be reflected.– It should make the best of 802.15.3c WPAN characteristics.– It should be flexible structure for optional usage.

• Next Step : We’d like to proceed to the optimal solution proposal with many interested individuals by the next meeting.

Doc.: IEEE 802.15-07/758r2 TG3c Presentation LG Electronics & SiBEAM 18/July/2007 Slide 1 Project:...

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