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Distributed Coordination Schemes for Multi-Radio Co-existence in Dense Spectrum Environments

-

An Experimental Study on the ORBIT Testbed

K.C. HuangXiangpeng Jing

Shanmuga S Anandaraman Mesut Ali Ergin

Ivan Seskar Dipankar Raychaudhuri

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Outline

Multi-radio co-existence issuesDistributed coordination schemes using Common Spectrum Coordination Channel (CSCC)

Scheme 1: radio backoff transferScheme 2: loading rate backoffScheme 3: SIR-based loading rate control

WiFi/Bluetooth system case studyScenario mapping on ORBIT testbedExperiment results

Conclusion and future work

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Motivation

Spectrum resource is scarceCurrent spectrum utilization is inefficient

Density of wireless devices (including multi-radio devices) will continue to increase

~10x with home gadgetsInteroperability between proliferating radio standards

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Typical Scenario -

SOHO

Devices: Multi-radio laptops, handheld, Bluetooth headset, sensors, etc.Clustered distribution in conference roomsDominate traffic:

WiFi data (web, email, file transfer, VoIP, video clip download, etc.)CBR/VBR Bluetooth voice/audio sessions

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Radio Technology Typical Range Max. Output Power FrequencyOccupied

Max. BitrateSupported

Typical Usage

802.11a/b/g/n (WIFI) 150-300 feet 17 dBm2.4 GHz ISM,5 Ghz UNII up to 248 Mbits/s

WLAN point-to-multipoint,Mixed web, file andstreaming traffic.

802.16 (WiMAX) 3-5 miles (12 miles)22 dBm (handheld),26 dBm BS

2.300-2.400 GHz,2.496-2.690 Ghz,3.300-3.800 GHz

4 Mbits/s (70Mbits/s)

WMAN broadband, Mixedweb, voice traffic.

802.15.1 (Bluetooth)150-300 feet (Class 1),15-30 feet (Class 2),3-4inch (Class 3)

20 dBm (Class 1),4 dBm (Class 2),0 dBm (Class 3)

2.4 ISM 3 Mbits/s (EDR)WPAN, low speedperipheral communicationsand voice/audio.

UWB/Wireless USB 30-100 feet -41dBm/Hz 3.1-10.6 GHz 500 Mbits/s WPAN, high-speedperipheral communications

802.15.4 (ZIGBEE) 33-246 feet3 dBm (currentimplementations)

868 MHz (EU),915 MHz (US),2.4GHz ISM

20-250Kbits/sWPAN, very low rate,intermittent traffic forsensors

Multi-radio Platforms

802.11b/g/n

Bluetooth

Frequency (2.412-2.483GHz)ZigBee

802.16a

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Co-existence Problems/Solutions

Intra-node Interference Multi-radios are on the same platform Physical separation/isolationIn-platform local time scheduling

Inter-node Interference Nearby multi-radios are in the dense areaDifferent interference range for different radiosSimple LBT or reactive frequency/rate/power control

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Common Spectrum Coordination Channel

(CSCC)

Explicitly coordinate spectrum usage for mutual observabilityPeriodic message exchange using a common signaling approachImplementation Type: Physical OR Logical control channelExecute coordination algorithms based on the information collectedPower controlRate control

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WiFi/Bluetooth Case Study on ORBIT

They are popular radios sharing 2.4GHzHardware and driver are easy to getRealistic scenario mapping onto ORBIT testbed

20x20 multi-radio gridEach node has two WiFi and one Bluetooth radios

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Coordination Algorithm Design Proposed loading rate control algorithms

Balance WiFi and BT throughput for satisfying service-level performanceCooperatively transmit to operate in “Co-existing” region

Conceptual relation

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Spectrum Coordination Algorithms (using CSCC)Simple BT-Backoff (BT-BO)

Any nearby WiFi receivers active? Bluetooth turns off its radio

BT-Rate adaptation (BT-RA)Adjust Bluetooth streaming rates when WiFi receivers detectedIn-platform WiFi receiver active? Bluetooth reduces to lowest levelNearby WiFi receiver active? Bluetooth lowers rate by one levelNo WiFi receivers detected? Increase rate to the highest level

SIR-based Bluetooth rate adaption (SIR-BT)WiFi receivers monitor total SIR including Bluetooth interferenceWiFi SIR falls below target? Bluetooth lowers rate

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ORBIT Experiment ParametersData session

WiFi: ON/OFF CBR with randomized sessionsBluetooth: Constant audio streaming (64, 128, 320, 512,1024kbps)

Inter-node and Intra-node interference

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Results

Wifi Throughput Bluetooth Throughput

1M 5M 10M 15M0

1

2

3

4

WiFi

offered load (bps)BT load 1Mbps

No CoordinationBT- RABT- BO

WiF

iAve

rage

Ses

sion

Thr

ough

put (

Mbp

s)

1M 5M 10M 15M0

50000

100000

150000

200000

250000

Blu

etoo

th S

essi

on T

hrou

ghpu

t (kb

ps) No Coordination

BT- RABT- BO

WiFi

offered load (bps)BT load 1Mbps

Any nearby WiFi receivers active? Bluetooth turns off its radioAdjust Bluetooth streaming levels when WiFi receivers detected

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WiFi

TCP File Transfer

WiFi senders and receivers transfer 1MB fileBluetooth has varying rate UDP streaming

Mapped scenario

WiFi-BT-TCP-Performance

0.005.00

10.0015.0020.0025.0030.0035.0040.00

NoInterfUnderInterf

BT-BO BT-RA SIR-BTTim

e to

Tra

nsm

it 1M

B fi

le

0.00E+002.00E+054.00E+056.00E+058.00E+051.00E+061.20E+061.40E+061.60E+061.80E+06

Thro

ughp

ut in

bps

WiFi-Transmit time BT-ThroughputInter-node Interference

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Conclusion and Future Work

Proliferating of multi-radio devices will cause both inter-node and intra-node radio interference severe

CSCC protocol allows explicit spectrum coordination between multi-radio platforms

Coordination algorithms in WiFi/Bluetooth caseCompared 3 algorithms balancing between WiFi and Bluetooth performanceSystem throughputs are greatly improved with cooperative loading rate control

Future workImprove the coordination algorithm handling traffic QoSStudy WiMax and Zigbee radios using ORBIT testbed

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Thank you!

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Multi-radio Platforms

Frequency (2.412-2.483GHz)ZigBee

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ORBIT Experiment ParametersData Radio Service

PHY Type IEEE 802.11g(AtherosAR5212)

Bluetooth(Belkin and IOgear

USB Dongle)

Frequency 2427-2447MHz 2402-2483.5MHz

Modulation OFDM (256 FFT) QAM

GFSK + FHSS

(DQPSK for EDR)

Transmit Power

18dBm 4dBm (~20m)(class 2)

20dBm (~100m)(class 1)

PHY Rate Up to 54MbpsAutoRate

Up to 1MbpsUp to 2.1Mbps

(w/ EDR)

Datasession

RandomON/OFF

CBR: 5 sec

Constant audiostreaming (64,128, 320, 512,

1024kbps)