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Nada Golmie, NISTSlide 1

doc.: IEEE 802.15-01/0063r0

Submission

IEEE P802.15 Working Group for Wireless Personal Area Networks

Power Control and Packet Scheduling for Bluetooth to Avoid 802.11 Direct Sequence Interference

Nada Golmie and Nicolas ChevrollierNational Institute of Standards and Technology

Gaithersburg, MD 20899USA

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Nada Golmie, NISTSlide 2

doc.: IEEE 802.15-01/0063r0

Submission

Outline• Non - Collaborative technique to improve

Bluetooth data traffic performance– Part I: Power control– Part II: Efficient frequency use

• Simulation Experiment Setup– Topology, parameters and traffic model used

• Results• Summary

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Nada Golmie, NISTSlide 3

doc.: IEEE 802.15-01/0063r0

Submission

Part I: Power Control• Update the power of the transmitter,

based on the receiver Carrier to Interference Ratio (CIR):

where and , are the transmitted power during update intervals t+1 and t respectively, and is the CIR measured during interval t.

tt

etT

t PCIRCIRP

arg

1

1tP

dBCIR etT 5arg 1tP tP

tCIR

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Nada Golmie, NISTSlide 4

doc.: IEEE 802.15-01/0063r0

Submission

Part II: Frequency Use• Construct a table of the available frequencies

based on the BER measurement at the receiver.

• Master checks both its available frequencies and the slave’s available frequencies before sending a packet to the slave.

Frequency Offset

...

01

78

Master BER Master Available Freq.0

1

0

Master Frequency Use Table

Slave Available Freq.0

1

1

Slave Sends to Master Updates on its Available Receive Frequencies

10^-2 < 10^-2 <

< 10^-3

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Nada Golmie, NISTSlide 5

doc.: IEEE 802.15-01/0063r0

Submission

Simulation Parameters

Length of Simulation RunBluetooth Parameters

30 secondsWLAN Parameters

DM1 Packet Interarrival TimeLoad Transmitted Power

1.25 ms Packet Interarrival TimeLoad

1.86ms 50% 50% 1mW 25 mWTransmitted Power

Slave Coordinates (0,0) (1,0)Master Coordinates

AP Coordinates (Sink)Mobile Coordinates (Source)

(0,15) (0,d)

Packet Header 224 bits

Slot Time

SIFS

DIFS CW_min CW_max RTS

20 us

10 us 50 us

31

1023 None

Update Interval 300 packets

DM1 Packet Interarrival TimeLoad

2.91 ms 30%

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Nada Golmie, NISTSlide 6

doc.: IEEE 802.15-01/0063r0

Submission

Topology

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Nada Golmie, NISTSlide 7

doc.: IEEE 802.15-01/0063r0

Submission

Traffic Model

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Nada Golmie, NISTSlide 8

doc.: IEEE 802.15-01/0063r0

Submission

Performance Measurements• Measurements are performed at the

Baseband:– Probability of packet loss– Normalized and mean access delay– Bluetooth transmitted power

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Nada Golmie, NISTSlide 9

doc.: IEEE 802.15-01/0063r0

Submission

Error Occurrences and Packet Acceptance Decisions

Error Location Action TakenError Correction

Access CodePacket HeaderDM1 payload

Hamming distance, d=141/3 FEC2/3 FEC

Drop Drop Drop

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Nada Golmie, NISTSlide 10

doc.: IEEE 802.15-01/0063r0

Submission

Packet Loss at Bluetooth Slave

0

0.05

0.1

0.15

0.2

0.25

0.005 0.01 0.02 0.05 0.075 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Distance of WLAN Mobile from Bluetooth Slave (meters)

prob

abili

ty o

f pac

ket l

oss

without scheduling (30%)

without sheduling (50%)

with scheduling (30% and 50%)

without Power Control

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Nada Golmie, NISTSlide 11

doc.: IEEE 802.15-01/0063r0

Submission

Bluetooth Master Power Transmitted

0

20

40

60

80

100

120

0.005 0.01 0.02 0.05 0.075 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Distance of WLAN Mobile from Bluetooth Slave (meters)

Pow

er m

aste

r (m

W)

Power max = 100 mW

Power in = 1 mW

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Nada Golmie, NISTSlide 12

doc.: IEEE 802.15-01/0063r0

Submission

Mean Access Delay for Bluetooth Slave

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.005 0.01 0.02 0.05 0.075 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Distance of WLAN Mobile from Bluetooth Slave (meters)

Mea

n A

cces

s D

elay

(sec

onds

)

with scheduling (30%)without scheduling (30%)with scheduling (50%)without scheduling (50%)without Power control

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Nada Golmie, NISTSlide 13

doc.: IEEE 802.15-01/0063r0

Submission

Normalized Mean Access Delay for Bluetooth Slave

0

0.5

1

1.5

2

2.5

0.005 0.01 0.02 0.05 0.075 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Distance of WLAN Mobile from Bluetooth Slave (meters)

Nor

mal

ized

Mea

n A

cces

s D

elay

with scheduling (30%)without scheduling (30%)with scheduling (50%)without scheduling (50%)

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Nada Golmie, NISTSlide 14

doc.: IEEE 802.15-01/0063r0

Submission

• Simple non-collaborative techniques can improve the performance of Bluetooth and IEEE 802.11:– control of Bluetooth transmitted power has

limited advantage (decreases packet loss for interference distance > 1 m) but at the cost of increasing the interference on the other devices.

– scheduling of Bluetooth LAN traffic to use non-interfering frequencies (available) eliminates packet loss and increases access delay by ~ 625 us.

Conclusions

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Nada Golmie, NISTSlide 15

doc.: IEEE 802.15-01/0063r0

Submission

• Evaluate the same technique for other DM packet sizes.

• Devise other techniques to deal with Bluetooth voice traffic, WLAN Frequency hopping systems.

Future Work