Doc.: IEEE 802.11-09/0803r0 Submission July 2009 John A. Stine, SelfSlide 1 Multi-Channel, Multi-Directional Contention Access Date: 2009-07-14 Authors:

doc.: IEEE 802.11-09/0803r0

Submission

July 2009

John A. Stine, SelfSlide 1

Multi-Channel, Multi-Directional Contention Access

Date: 2009-07-14

Name Affiliations Address Phone email

John A. Stine Self 9322 Eagle Court Manassas Park, VA

703-983-6281 [email protected]

Authors:

John Stine is employed by The MITRE Corporation but represents himself in this presentation. The MITRE Corporation is a not for profit company and has no economic interest in the outcome of the 802 standards process. The author's affiliation with The MITRE Corporation is provided for identification purposes only, and is not intended to convey or imply MITRE's concurrence with, or support for, the positions, opinions or viewpoints expressed by the author.MITRE Public Release #09-2480

doc.: IEEE 802.11-09/0803r0

Submission

Patent Statement

• Methods described in this presentation are covered in claims in patents and patents pending.

• The MITRE Corporation is a not for profit company that does not own the patents and has no economic stake in the outcome of the 802 standards activity


July 2009

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Abstract

• TGad intends to create a very high throughput technology that anticipates using broad bands of spectrum and beamforming technologies

• This presentation provides an overview of the Synchronous Collision Resolution (SCR) contention-based MAC protocol and its ability to enable very high throughput by– Arbitrating the use of multiple channels in the same LAN concurrently– Creating the conditions for CDMA use and SDMA– Creating the conditions for beamforming or null steering during

contention at both the source and destination ends of a link– Integrating the use of multiple antenna technologies in the same network.


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The Larger Story

Designing for Coexistence Design by rules coexistence Arbitrating the use of space, time, and frequency

Multichannel Multi-directional Contention Access

Arbitrating channel useCreating directional diversityEnabling adaptation

Contention Mechanisms for Quality of Service and Energy Conservation

Differentiated servicesBandwidth reservation for streamingMultiple dozing modes (default, opportunistic, coordinated)

Synchronization Mechanisms Course synchronizationFine synchronizationToA Techniques

Slide 4

July 2009

John A. Stine, Self

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REVIEW

July2009

John Stine, SelfSlide 5

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The Message from “Designing for Coexistence” - 1

Slide 6

July 2009

John A. Stine, Self

• Listen-before-talk methods of sharing do not solve the contentious issues in spectrum sharing across technologies– Suffers from all the same problems as carrier sensing protocols

• Hidden terminals• Exposed terminals• Deafness• Muteness

– Still suffers “tragedy of the commons”• Can I beat the other guy’s backoff scheme

– Returns the sharing problem to “tyranny of the incumbent”• You have to be able to sense my signal and I don’t have to sense yours• You better not send any signals I interpret incorrectly

• SCR does not suffer these shortcomings

doc.: IEEE 802.11-09/0803r0

Submission

The Message from “Designing for Coexistence” - 2

Slide 7

July 2009

John A. Stine, Self

• SCR enables sharing across all RF spectrum’s dimensions: space, time and frequency

• All technologies, present or future, that work within the rules of the SCR contention can coexist fairly

• This technique can also serve as a very effective contention-based access mechanism for high throughput applications

doc.: IEEE 802.11-09/0803r0

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Characteristics of Synchronous Collision Resolution

• Time slotted channels with common time boundaries

• Nodes with packets to send contend in every slot

• Signaling is used to arbitrate contention

• Packet transmissions occur simultaneously A paradigm not a specific design

CR Signaling

Transmission Slot

…


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Purpose of Collision Resolution Signaling

• Prune the set of contenders to a subset which can transmit without colliding

Red nodes are contendersRed nodes are contenders Red nodes are winnersRed nodes are winners

Signaling Process

CR Signaling

Transmission Slot

...

...1 2 3 4 5 6 7 8 9

Signaling slots

Signaling phases

Assertion signals


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Arbitrating Space and Time

• Signaling without Echoing– Resolves to a subset of

contenders separated by at least the range of their signals

• Demonstration

• Survivor Density ~ usually >1.4

Slide 10

July 2009

...

...1 2 3 4 5 6 7 8 9

Signaling slots

Signaling phases

John A. Stine, Self

doc.: IEEE 802.11-09/0803r0

Submission

Arbitrating Space and Time - 2

• Signaling with Echoing– Resolves to a subset of

contenders where interferering node are at least one radio range away from destinations

• Demonstration• Survivor Density ~ 0.5-

0.8

Slide 11

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...

...1 2 8 9

E E

3 4 5 6 7

E E E E E E ESignaling slots

Signaling phases

John A. Stine, Self

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Arbitrating Channels among Technologies

• Stations may contend for multiple channels – Signals contain the tones of the channels a station wants to use

– A station may win the right to use a subset of the channels it initially contends to use

Channels systems want

Signaling Schedule Channels systems receive

Station of system A

Station of system C

Station of system B

The signals in this scenario


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Significant Take Aways

• SCR arbitrates time, space, and frequency

• Signaling can be the common arbitration mechanism and made independent of the rest of the frame– Multiple technologies can coexist

– Technologies can evolve with fewer legacy constraints

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Slide 13

CR Signaling

Transmission Slot

Common Multiple technologies can coexist here

John A. Stine, Self

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EXPLOITING MULTIPLE CHANNELS IN A NETWORK

July 2009

Slide 14 John A. Stine, Self

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Why is it challenging to use multiple channels?

• In most contention protocols, it is ambiguous on which channel idle nodes should listen– Broadcast channel (necessary for discovery)– Peer-to-peer channel

• Number of choices depends on channel association– Transmitter directed and pairwise association result in an indefinite number of choices– Receiver directed results in two possible choices

• Increasing capacity requires relaxing carrier and virtual sensing mechanisms

• Near-far effect is an issue when DSSS CDMA is used to create channels


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Contention mechanisms to channelize -1

• Touch and go strategies– Contention on a common channel

– Either the transmitter or receiver chooses the channel• Best for the receiver to choose the channel because it can choose a

channel that will not interfere with its reception

• The selected channel is used for the packet exchange

– Issues• How do you do broadcasts once some nodes are on different channels

• How do hidden terminals track which channels are being used

• How do radios track which nodes are busy on different channels


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Contention mechanisms to channelize -2

• Hop and stay strategies– Nodes contend on a rolling channel schedule using short

transmissions to initialize a contention and then stay in that channel if successful

– Exchanges on a channel should finish before that channel returns in the rotation

– Issues• How do you do broadcasts once some nodes are on different channels

• How do radios track which nodes are busy on different channels

• Can the channels in the rotation be changed dynamically


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Resolving Which Channel to Use

• Assigning channels in SCR– A shared broadcast channel

– Receiver directed peer-to-peer channels (Nodes select their channel and advertise it to their neighbors)

• How do destinations know which channel to listen to– Use priorities to distinguish broadcast and peer-to-peer transmissions

– Neighbors that hear a broadcast priority used to gain access listen on the broadcast channel otherwise they listen on their peer-to-peer channel

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Slide 18

...

...1 2 3 4 5 6 7 8 9

Signaling slots

Signaling phases

Peer-

to-

peer

Bro

adca

st

Priority Phase

Bro

adca

st Peer-

to-

peer

Bro

adca

st Peer-

to-

peer

Peer-

to-

peer

John A. Stine, Self

doc.: IEEE 802.11-09/0803r0

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Challenges using CDMA

Asynchronous Access Synchronous Access

Why PG cannot be exploited with the 802.11 MAC

S1

D1

Both sources and destinations must be separated from each other

Sources and destinations may be clustered together

D3

S3

S2D2

S1

S2

D1

D2

D3

S3

S4

D4

S5

D5

S6

D6


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Combined benefit of SCR’s spatial separation and channelization

• Multiple sources sending multiple packets on different channels to multiple destinations simultaneously in a manner reminiscent of cellular telephony

• Synchronization and geometry mitigate the near-far effect and create the conditions necessary for smart antenna use


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USING SIGNALING TO RESOLVE BEAM STEERING

July 2009


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Challenges for Asynchronous CSMA Approaches

• Conceptually based on omni-directional transmissions

July 2009

Slide 22

APS-S APS-DAPS

ACS

AI

ACS-S

AI-S AI-D

• CSMA problems occur when nodes outside the sensing regions attempt to reach nodes inside the region

– Deafness occurs when the destination is interfered with by another transmitter

– Muteness occurs when the destination is virtual sensing

• Omnidirectional contention in access point networks typically preclude these problems but this would not be the case with directional antennas

John A. Stine, Self

• Depending on when directionality is used increases the probability of deafness and muteness problems

doc.: IEEE 802.11-09/0803r0

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Directional Signaling• Assumes sources know the direction to destinations

• Uses an echo design

• Signaling rules– Rules the same as those for signal echoing designs except

• Contenders send priority signaling in all directions they might possibly receive

• Contenders send CRS signals either in the direction of their destinations or in all directions they have not received echoes

• Non-signalers listen and echo in all directions they might possibly receive

• Contenders defer directionally after receiving echoes

– In AP network, all non-AP stations can permanently point toward the AP

July 2009

Slide 23

...

...1 2 8 9

E E

3 4 5 6 7


Signaling phases

John A. Stine, Self

doc.: IEEE 802.11-09/0803r0

Submission

Directional Signaling Scenario

July 2009

Slide 24

4.5 m

3.0 m

door

window

STA 1

STA 2

STA 3

STA 4

STA 5

STA 6

STA 7

STA 8

AP (in ceiling)

7 m

7 m

TV

STB

• Antennas may have a fixed directionality or be electronically steered

• Pointing– For contenders occurs before signaling– For destinations is resolved during

contention– Single direction would be manually

pointed– Sectored antennas use the best antenna

and must learn direction– Electronically steered antennas must learn

direction

• Different antenna technologies can work with each other

1.8 m

2.5

m

1.0 m

1.0

m

1.0 m

1.0

m

25 meter

25

me

ter

AP

John A. Stine, Self

doc.: IEEE 802.11-09/0803r0

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......C C ...C C C CE E E E E E EP

Contention SlotEcho Slot Promotion Slot

First Reduction Period

Second Reduction Period

Promotion Phase

Signaling slots

Signaling phases

Synchronized Unscheduled Multiple Access

• An SCR design that use echoing

• Adds a promotion phase to increase the density of survivors from signaling at the cost of more signaling


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SUMA versus D-SUMA example

July 2009

Slide 26

Contention signaling is in all directions except those you hear echoes

John A. Stine, Self

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ADAPTIVE BEAMSTEERING

July 2009


doc.: IEEE 802.11-09/0803r0

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Observation on Adaptation

• We want adaptation to improve the strength of a received signal but also reject interference from neighbors

• Adaptation is difficult in cases of coincident transmitters and congestion

• Adaptation cannot anticipate future conditions and is susceptible to new interference

Nulling breaks down after n-1 interfering nodes

0 60 120 180 240 300 36060

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Gai

n (d

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n (d

B)

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n (d

B)

Gai

n (d

B)

Azimutha. (5, 0.5, 100, 30, 120)

Azimuth

Azimuth Azimuth

b. (5, 0.5, 100, 30, 105)

c. (5, 0.5, 100, 30, 120, 220) d. (5, 0.5, 100, 30, 120, 220, 300, 340)

(n, d, , 1, 2,…)n – number of elementsd – spacing between

elements – pointing direction – null directions

Steering using the Max SINR algorithms


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Conditions for smart antenna use

• Simple pointing1. Know where to point

2. Know where not to point

• Adaptive pointing and null steering (also necessary for MIMO)3. Capture the condition

4. Prevent multiple transmitters in the near same direction

5. Prevent congestion

6. Preserve the condition

Protocols direct the physical layer

Protocols create the conditions that allow the physical layer to adapt effectively


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Submission

Generic antenna adaptation model

Capture Adaptation Packet

ts tft

Letts = time it takes a source to capture a signaltf = time sampling ends for adaptationSIRc = minimum SIR to capture the desired

signalSIRa = minimum SIR to adaptta = time an interfering signal arrivestsm = minimum time required to sample a

signal for adaptation

A receiving antenna can adapt and point toward a source if

SIR > SIRc t, t ts

SIR > SIRa t, ts t tf

A receiving antenna can adapt and point a null toward an interfering source if the conditions above and

ta tf - tsm

J. Ward and R. T. Compton, Jr., “Improving the performance of a slotted ALOHA packet radio network with an adaptive array,” IEEE Trans. Communications, Vol. 40, Feb. 1992, pp. 292-300.


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Protocol Additions for Adaptation

July 2009

• The RTS-CTS exchange has two roles– Verify capture – Provide a feedback mechanism

• to optimize link performance (e.g. adapt antennas, adjust power)• to synchronize nodes using TDOA

• Observations– All RTS transmissions occur simultaneously and all CTS transmissions

occur simultaneously– Network interference is worst during these exchanges– Subsequent adjustments improve overall capture conditions

• Dropped contenders• Lower transmission power• Optimized antennas

CR Signaling

RTS CTS Protocol Data Unit ACK

Transmission Slot


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RTS – CTS Example

23 source-destination pairs 16 successful RTS exchanges 16 successful CTS exchanges

July 2009


doc.: IEEE 802.11-09/0803r0

Submission

SCR creates the adaptive antenna conditions

• Adaptive pointing and null steering conditions3. Capture the condition4. Prevent multiple transmitters in the near same direction5. Prevent congestion6. Preserve the condition

• SCR creates all the conditions for adaptive pointing and null steering

– The RTS-CTS exchange allows both sources and destinations to identify where interference is coming from

– CRS prevents multiple contenders in the same direction

– CRS prevents congestion– Conditions are preserved throughout the PDU and

ACK transmissions

No more than 2 to 3 interfering nodes in range of any receiver after CRS and all in diverse directions(Dark blue nodes are transmitters)


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Important Observations

• SCR creates the conditions that allow your high capacity technologies to excel

• Multiple technologies are completely compatible– Directional signaling with omnidirectional signaling

– Directional signaling with antenna adaptation

– Different antenna pointing technologies

• Any set of transmission technologies can coexist well given their use of SCR signaling to arbitrate time, space, and frequency

• Provides a solution that allows an easier technology evolution to occur

July 2009


doc.: IEEE 802.11-09/0803r0

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Conclusion

• SCR provides a contention-based access mechanism that supports the exploitation of channelization and antenna technologies to achieve high throughput

• Asynchronous CSMA-based protocols cannot compete


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References• J. A. Stine, “Exploiting processing gain in wireless ad hoc networks using synchronous collision

resolution medium access control schemes,” Proc. IEEE WCNC, Mar 2005. • J.A. Stine, “Cooperative contention-based MAC protocols and smart antennas in Mobile Ad Hoc

Networks,” Chapter 8 in Distributed Antenna Systems: Open Architecture for Future Wireless Communications, Auerbach Publications, Editors H. Hu, Y. Zhang, and J. Luo. 2007.

• K. H. Grace, J. A. Stine, R. C. Durst, “An approach for modestly directional communications in mobile ad hoc networks,” Telecommunications Systems J., March/April 2005, pp. 281 – 296.

• J. A. Stine, “Modeling smart antennas in synchronous ad hoc networks using OPNET’s pipeline stages,” Proc. OPNETWORK, 2005.

• J. A. Stine, “Exploiting smart antennas in wireless mesh networks,” IEEE Wireless Comm Mag. Apr 2006.• J. M. Peha, “Sharing Spectrum through Spectrum Policy Reform and Cognitive Radio,” TBP Proc. of the

IEEE, 2009.• J. A. Stine, “Enabling secondary spectrum markets using ad hoc and mesh networking protocols,”

Academy Publisher J. of Commun., Vol. 1, No. 1, April 2006, pp. 26 - 37.• J. Stine, G. de Veciana, K. Grace, and R. Durst, “Orchestrating spatial reuse in wireless ad hoc networks

using Synchronous Collision Resolution,” J. of Interconnection Networks, Vol. 3 No. 3 & 4, Sep. and Dec. 2002, pp. 167 – 195.

• J.A. Stine and G. de Veciana, “A paradigm for quality of service in wireless ad hoc networks using synchronous signaling and node states,” IEEE J. Selected Areas of Communications, Sep 2004.

• J. A. Stine and G. de Veciana, “A comprehensive energy conservation solution for mobile ad hoc networks,” IEEE Int. Communication Conf., 2002, pp. 3341 - 3345.

• K. Grace, “”SUMA – The synchronous unscheduled multiple access protocol for mobile ad hoc networks,” IEEE ICCCN, 2002.


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

The Larger Story

Designing for Coexistence Design by rules coexistence Arbitrating the use of space, time, and frequency

Multichannel Multi-directional Contention Access

Arbitrating channel useCreating directional diversityEnabling adaptation

Contention Mechanisms for Quality of Service and Energy Conservation

Differentiated servicesBandwidth reservation for streamingMultiple dozing modes (default, opportunistic, coordinated)

Synchronization Mechanisms Course synchronizationFine synchronizationToA Techniques

Slide 37

July 2009

John A. Stine, Self

doc.: IEEE 802.11-09/0803r0

Submission

Backup Summary

• Hurdles in designing signaling rules• CRS Rules

– Without Echoing

– With Echoing

• Signaling Walkthrough• CRS effectiveness• Signaling Design• Spatial reuse• Simulation results

– Processing gain

– Antenna Adaptation

July 2009


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July 2009

Backup


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The Hurdles in Designing the Rules

• Methods to synchronize different technologies

• Agreement on – The features to include in the signaling

– Precedence in arbitration

– Boundaries on slots and channels

– The common signals

– The synchronization bounds


July 2009

The Original

Sins

doc.: IEEE 802.11-09/0803r0

Submission

Rules of Collision Resolution Signaling (CRS)

• Rules of single slot signaling– At the beginning of each signaling phase a contending node

determines if it will signal. (The contending node will signal with the probability assigned to that phase.)

– A contender survives a phase by signaling in a slot or by not signaling and not hearing another contender’s signal. A contender that does not signal and hears another contender’s signal loses the contention and defers from contending any further in that transmission slot.

– Nodes that survive all phases win the contention

...

...1 2 3 4 5 6 7 8 9

Signaling slots

Signaling phases


July 2009

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Rules of Collision Resolution Signaling (CRS)

• Rules of signaling phases that use echoing– At the beginning of the signaling phase a contending node

determines if it will signal. A contending node will signal in the first slot with the probability assigned to that phase.

– Any node that does not signal in the first slot but hears a signal sends a signal in the second slot.

– A contender survives the phase by signaling in the first slot or by not signaling and not hearing another contender’s signal in the first slot nor an echo in the second slot. A contender that does not signal and hears another contender’s signal or hears an echo loses the contention and defers from contending any further in that transmission slot

...

...1 2 8 9

E E

3 4 5 6 7


Signaling phases


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Collision Resolution Signaling Example - 1

In this example all nodes start off as contenders

All contending nodes do a random number draw and those beneath a specified threshold transmit a signal. Signalers and those that do not hear the signal survive this phase of the signaling

Red = contenderGray = non-contender


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Signaling and attrition proceeds for several iterations with the threshold for signaling changing for each phase


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• The end result of collision resolution signaling– When all nodes are in range of

each other – one surviving node

– In a multihop environment as shown – a set of surviving nodes separated by the range of their signals

• The range of signaling’s effect can be extended by using echoing (See subsequent slides)

DemonstrationJohn A. Stine, SelfSlide 47

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Submission

Echoing Example

Red = contenderGray = non-contenderBlue square = echoer

75 contenders after contention 19 contenders after echoing

DemonstrationJohn A. Stine, SelfSlide 48

July 2009

doc.: IEEE 802.11-09/0803r0

Submission

How effective is CRS in resolving contention ?

• It is a function of design, # of signaling phases, threshold probabilities for signaling

• We have a simple design methodology that yields the performance illustrated

0 10 20 30 40 500.75

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1

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k

Number of Contenders

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P(O

ne S

urvi

vor)

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Uk2 1 0

Sk2 1 0

k2

kt = 50kt = 200

kt = 500 kt = 1000


P(O

ne S

urvi

vor)

4, 5, 6 , 7, 8, and 9 single-slot phase designs optimized for a 50 contender density

Comparison of 9 single-slot phase designs optimized for various target densities of contenders

> 99% of the transmissions slots can be resolved to one transmitter for all practical densities of contenders!


July 2009

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Submission

How well does signaling isolate just one survivor?

• Consider a signaling design where all phases have one slot

• Let px be the probability that a contending node will signal in phase x

• A transition matrix may be populated where the element k,s corresponds to the probability that s of k contending nodes survive the signaling phase

s k sx x

k kx x xk,s

kp 1 p 0 s k

s

p 1 p 0 s k

0 otherwise .

P

...

...1 2 3 4 5 6 7 8 9

Signaling slots

Signaling phases


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Submission

How well does signaling isolate just one survivor? (2)• The transition matrix of the signaling process with n phases may be calculated

• The probability that just 1 of k contending nodes survives signaling is

• It is easy to optimally select a set of probabilities that maximizes the probability that there will be 1 survivor when there are some k = k1 contenders at the beginning but this problem formulation may result in a lower probability that one survivor remains when there are k < k1 contenders.

nn x

x 1Q P

nk,1Q

P(one survivor)

k

Improvement at k1 may results in decreased performance at k < k1

k1


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0 10 20 30 40 500.75

0.8

0.85

0.9

0.95

1

P4k 1 0

P5k 1 0

P6k 1 0

P7k 1 0

P8k 1 0

P9k 1 0

k


4 slots

5 slots

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P(O

ne S

urvi

vor)

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0.985

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Qk2 1 0

Uk2 1 0

Sk2 1 0

k2

kt = 50kt = 200

kt = 500 kt = 1000


P(O

ne S

urvi

vor)

How well does signaling isolate just one survivor? (3)• A redefined optimization problem

– Let qn be the set of px for an n phase CRS design

– Let kt be a target density of contending nodes

– Let m be the total number of signaling slots allowed (in this case n = m)

– Let S(qn,kt,m) be the probability that there will be only one surviving contender

max

s.t. .

n

nt

q

n nt t

S q ,k ,m

S q ,k ,m S q ,k ,m k ,0 k k

4, 5, 6 , 7, 8, and 9 single-slot phase designs optimized for a 50 contender density

Comparison of 9 single-slot phase designs optimized for various target densities of contenders


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Submission

Density of range to the nearest surviving neighbor when the average contending neighbor density is10

0

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0.00

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Fraction of Range

Fra

cti

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Simulated survivor densities using a 9-phase CRS design, kt = 50

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Contender Density, A

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A

Spatial Reuse-1

• Simulations of signaling without echoes reveal– The density of survivors levels off at about 1.4 survivors per signaling area (the area covered by

the range of a signal)– Depending on signaling effectiveness, survivors are separated by at least the range of their signals


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Submission

Spatial Reuse-2

• Simulations of signaling with echoes reveal– The density of survivors decreases with contender density

– Average separation range increases with the density of the contenders

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Simulated survivor densities using SUMA version of signaling

Density of range to the nearest surviving neighbor using SUMA version of signaling

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2 5 8 10 15 20 25

Contender Density, A

Su

rviv

or

Den

sity

, S

A


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

SIMULATIONS AND RESULTS

July 2009


doc.: IEEE 802.11-09/0803r0

Submission

Some Results (10 dB PG)

July 2009

Slide 56

SCR allows destinations to clusterJohn A. Stine, Self

doc.: IEEE 802.11-09/0803r0

Submission

The effectiveness of processing gain

• Issue: How well does processing gain improve capacity

• Experiment: – 156 nodes randomly placed on a toroidally wrapped

square surface with a side (7* radio_range) which results in a network

with an average degree of 10 – Perfect routing assuming a potential

connection when SNR is >10dB

– Poisson arrival of packets uniformly distributed amongst the nodes with randomly and uniformly selected destinations

– Packets timed-out after 8 seconds

– Packets queued by priority earliest expiration time first

– Signaling designs, processing gains, and routing strategies are varied


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

The effectiveness of processing gain - 2

• Standard signaling– 9 phase signaling design and two priority levels, broadcast and peer-to-peer

– Signals detected if 10 dB SNR (i.e. signal range is the same as the maximum range for a link)

• Processing gain dramatically improves capacity

TABLE I EXPERIMENT SETTINGS

ID PG Description 1 0 Standard 2 10 dB Standard 3 20 dB Standard 4 30 dB Standard 5 0 5 dB SNR for signal detection 6 10 dB 5 dB SNR for signal detection 7 10 dB 5 phase signaling design 8 20 dB 5 phase signaling design 9 30 dB 5 phase signaling design

10 10 dB Half power CRS signal strength 11 20 dB Half power CRS signal strength 12 30 dB Half power CRS signal strength 13 0 1 retry before invoking echoing 14 10 dB 1 retry before invoking echoing 15 0 11 phase signal design and 1 retry before invoking echoing 16 0 5 dB SNR for signal detection and 15 dB SNR for link

detection 17 0 20 dB SNR for link detection

0 200 400 600 800 1000 1200 1400 16000

500

1000

1500

2000

2500

3000

MT k 0

MT k 1

MT k 2

MT k 3

Ik 0

1

2

3

4

Packet arrival rate (pkts/sec)

MAC packet throughput (pkts/sec)


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

The effectiveness of processing gain - 4

• Less effective signaling improves performance when there is high processing gain

TABLE I EXPERIMENT SETTINGS

ID PG Description 1 0 Standard 2 10 dB Standard 3 20 dB Standard 4 30 dB Standard 5 0 5 dB SNR for signal detection 6 10 dB 5 dB SNR for signal detection 7 10 dB 5 phase signaling design 8 20 dB 5 phase signaling design 9 30 dB 5 phase signaling design

10 10 dB Half power CRS signal strength 11 20 dB Half power CRS signal strength 12 30 dB Half power CRS signal strength 13 0 1 retry before invoking echoing 14 10 dB 1 retry before invoking echoing 15 0 11 phase signal design and 1 retry before invoking echoing 16 0 5 dB SNR for signal detection and 15 dB SNR for link

detection 17 0 20 dB SNR for link detection

0 200 400 600 800 1000 1200 1400 16000

500

1000

1500

2000

2500

3000

MT k 1

MT k 2

MT k 3

MT k 6

MT k 7

MT k 8

MT k 9

MT k 10

MT k 11

Ik 0

2

3

4

7

10

8, 9, 11, 12




July 2009

doc.: IEEE 802.11-09/0803r0

Submission

The effect of adaptive antenna technologies

• Issue: How well do adaptive antenna technologies improve capacity

• Experiment: – 156 nodes randomly placed on a toroidally wrapped

square surface with a side (7* radio_range) which results in a network

with an average degree of 10 – Perfect routing assuming a potential

connection when SNR is >10dB– Poisson arrival of packets uniformly

distributed amongst the nodes with randomly and uniformly selected destinations

– Packets timed-out after 8 seconds– Packets queued by priority earliest expiration

time first– Antenna technologies and strategies are varied


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Evaluation of Protocol Pointing• Sources point antennas toward

destinations while destination listen omnidirectionally

• Destinations look up the source direction and point back toward the source starting with the CTS

• Simulations assume perfect knowledge of distant node direction (This is an evaluation of the effect of antenna technology on capacity not the performance of a protocol to track direction)

ID Tech BWFN MSLL (dB)

SIRc

(dB) ts

(s) SIRa

(dB) tf -tsm

(s) AG (dB)

1 omni 0 2 SP 60 -12 3 SP 30 -12 4 SP 10 -12 5 SP 60 -20 6 SP 30 -20 7 SP 10 -20 8 SP 60 -30 9 SP 30 -30

10 SP 10 -30

0 200 400 600 800 1000 1200 1400 16000

500

1000

1500

2000

2500

3000

Ms k 0

Ms k 1

Ms k 2

Ms k 3

Ms k 4

Ms k 5

Ms k 6

Ms k 7

Ms k 8

Ms k 9

Ik 0



1

2

34

5

6

8 9 107


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Effect of Antenna Directivity and Selectivity

• Wanted to determine benefits of trading main beam width for reduced sidelobe levels

• Experiment involves varying the width of the main beam (BWFN) and the size of the ball (MSLL) when using the protocol pointing technique with a single traffic scenario (1100 pkts/sec)

• Experiments show that once MSLL is below -15dB that directivity is most important

10 20 30 40 50 601000

1500

2000

2500

3000

K v 2

K v 3

K v 4

Kv 0

30 25 20 15 10 51000

1500

2000

2500

3000

Lv 2

Lv 3

Lv 4

Lv 0

MSLL BWFN

MAC packet throughput (pkts/sec) MAC packet throughput (pkts/sec)

60°

30°

10°

-12 dB

-20 dB

-30 dB

Holding beamwidth constant Holding MSLL constant

X Y Z( )


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Evaluation of Adaptive Pointing

• Sources point antennas toward destinations while destinations listen omnidirectionally

• Destinations adapt to incoming signals and point after the training sequence

• Simulations assume perfect directional adaptation

• Improvements over protocol pointing occur since the RTS is received while both nodes point


SIRc

(dB) ts

(s) SIRa

(dB) tf -tsm

(s) AG (dB)

1 omni 0 2a SP 60 -12 6 1 3 100 3a SP 30 -12 6 1 3 100 4a SP 10 -12 6 1 3 100 5a SP 60 -20 6 1 3 100 6a SP 30 -20 6 1 3 100 7a SP 10 -20 6 1 3 100 8a SP 60 -30 6 1 3 100 9a SP 30 -30 6 1 3 100

10a SP 10 -30 6 1 3 100

0 200 400 600 800 1000 1200 1400 16000

500

1000

1500

2000

2500

3000

Ma k 0

Ma k 1

Ma k 2

Ma k 3

Ma k 4

Ma k 5

Ma k 6

Ma k 7

Ma k 8

Ma k 9

Ik 0



1

2a3a

4a

5a

6a8a9a 10a

7a


July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Evaluation of Environmentally Adaptive Reception

• All transmissions are directional and destinations initially listen omnidirectionally

• Destinations adapt to incoming signals and if adaptation criteria is met reduce the gain of the interfering transmitters

• Adaptation gain had no noticeable effect on performance

• Transmitter directivity remains a key performance parameter

• The sensitivity of adaptation had a large effect on performance


SIRc

(dB) ts

(s) SIRa

(dB) tf -tsm

(s) AG (dB)

11 EAR 60 -12 6 1 3 100 -12 12 EAR 60 -12 6 1 3 100 -20 13 EAR 30 -12 6 1 3 100 -12 14 EAR 30 -12 6 1 3 100 -20 15 EAR 10 -12 6 1 3 100 -12 16 EAR 10 -12 6 1 3 100 -20 17 EAR 60 -12 3 1 1 100 -12 18 EAR 60 -12 3 1 1 100 -20 19 EAR 30 -12 3 1 1 100 -12 20 EAR 30 -12 3 1 1 100 -20 21 EAR 10 -12 3 1 1 100 -12 22 EAR 10 -12 3 1 1 100 -20

0 200 400 600 800 1000 1200 1400 16001800

2000

2200

2400

2600

2800

Ms k 10

Ms k 11

Ms k 12

Ms k 13

Ms k 14

Ms k 15

Ms k 16

Ms k 17

Ms k 18

Ms k 19

Ms k 20

Ms k 21

Ik 0

11 12

13

14

15

161718

2019

21

22




July 2009

doc.: IEEE 802.11-09/0803r0

Submission

Environmentally Adaptive Reception and Transmission• First RTS transmission is

directional and destinations initially listen omnidirectionally

• Destinations adapt to incoming signals and if adaptation criteria is met reduce the gain of the interfering transmitters

• The same adaptation is applied in subsequent transmissions in the transmission slot and power is reduced by AG toward non-destination receivers

• Adaptation gain has an effect on performance

• The improvement of EART over EAR is barely noticeable


SIRc

(dB) ts

(s) SIRa

(dB) tf -tsm

(s) AG (dB)

11a EART 60 -12 6 1 3 100 -12 12a EART 60 -12 6 1 3 100 -20 13a EART 30 -12 6 1 3 100 -12 14a EART 30 -12 6 1 3 100 -20 15a EART 10 -12 6 1 3 100 -12 16a EART 10 -12 6 1 3 100 -20 17a EART 60 -12 3 1 1 100 -12 18a EART 60 -12 3 1 1 100 -20 19a EART 30 -12 3 1 1 100 -12 20a EART 30 -12 3 1 1 100 -20 21a EART 10 -12 3 1 1 100 -12 22a EART 10 -12 3 1 1 100 -20

0 200 400 600 800 1000 1200 1400 16001800

2000

2200

2400

2600

2800

Ma k 10

Ma k 11

Ma k 12

Ma k 13

Ma k 14

Ma k 15

Ma k 16

Ma k 17

Ma k 18

Ma k 19

Ma k 20

Ma k 21

Ik 0

11a

12a

13a14a15a

16a17a

18a20a

19a

21a 22a




July 2009

Documents

Doc.: IEEE 802.11-09/0803r0 Submission July 2009 John A. Stine, SelfSlide 1 Multi-Channel, Multi-Directional Contention Access Date: 2009-07-14 Authors: