1. Error Rate Results of OFDM from Bluetooth Interference
11/29/2018
doc.: IEEE /xxx
May 2001
Error Rate Results of OFDM from Bluetooth Interference
John Terry, Ph.D.
Nokia Research Center
Irving, TX
J. Terry, Nokia
Sunghyun Choi, Philips Research

2. Outline Motivation Model used for analysis and simulation
May 2001
Outline
Motivation
Model used for analysis and simulation
Simulation results
Conclusions
J. Terry, Nokia

3. Motivation for Analysis
May 2001
Motivation for Analysis
March 2001, IEEE TGg meeting considerable discussion took place concerning the performance of PBCC and OFDM in the face of Bluetooth (BT) interference
Nokia was one of the four founding members of Bluetooth SIG and has a considerable stake in the technology
Nokia currently has IEEE802.11b products in the 2.4 GHz band with product road maps for both 2.4 and 5 GHz IEEE WLAN products
Both BT and IEEE are important to Nokia
J. Terry, Nokia

4. May 2001
Questions
Does OFDM have any special properties to cancel BT interference?
What is the packet loss rate in the face of BT pico nets?
What benefit is provided by using erasures?
How much does the performance of OFDM system further degrades in the presence of multiple BT interferers?
Do the sychronization algorithms used at the receiver have an impact on the erasures' performance?
What are the SIR and SNR levels where the all packets are loss?
J. Terry, Nokia

5. Approach to Answer Question
May 2001
Approach to Answer Question
Focus on effects of BT interference on OFDM first as NRC Dallas has detailed simulation models down to the fixed point level for IEEE802.11a
“Off the shelf” OFDM receiver design based upon IEEE802.11a is used for baseline (no Barker preamble)
Performance without any special interference canceling algorithms are applied in the OFDM receiver for simulation study for various SIR levels
Performance with erasures specified at the receiver.
J. Terry, Nokia

6. BT Interference Model GFSK modulation operating at 1 Msps
May 2001
BT Interference Model
GFSK modulation operating at 1 Msps
BT=0.5 with 1600 hops/sec
Power levels simulated were [ ] dB
11 Erasures are used
Total of 11*312.5KHz=3.44 MHz of spectrum is removed
1 and 3 BT pico net environments are examined
Phop=17/79=21.5% for 1 BT
Phop ~ 50% for 3 BT
Extracted from document IEEE /061r0
J. Terry, Nokia

7. Symbol Constellation w/ 0 dB BT Interference
May 2001
Symbol Constellation w/ 0 dB BT Interference
J. Terry, Nokia

8. Symbol Constellation w/ 0 dB BT Interference and Erasures
May 2001
Symbol Constellation w/ 0 dB BT Interference and Erasures
J. Terry, Nokia

9. 802.11a Simulation Parameters
May 2001
802.11a Simulation Parameters
24 Mbps mode
16 QAM, rate 1/2 convolutional coding, and bit Interleaving
48 Mbps mode
64 QAM, rate 2/3 punctured convolutional coding, and bit interleaving
Includes packet detection, frequency offset correction, channel estimation/correction, fine time estimation
Channels:
Exponential Decay 5 tap Rayleigh channel
Packet Length of 100 Bytes
Subcarrier spacing KHz
J. Terry, Nokia

10. Scenario #1 Environment: 1 BT pico net Channel: 5 tap Rayleigh channel
May 2001
Scenario #1
Environment: 1 BT pico net
Channel: 5 tap Rayleigh channel
SIR: [20, 10, 0, -10, -20]
Data Rate: 24 Mbps
J. Terry, Nokia

11. 24 Mbps PER Simulations May 2001 J. Terry, Nokia 10 11 12 13 14 15 1617 18 19 20 -3 -2 -1
Packet Error Rate, IEEE802.11a 24Mbit mode, Rayleigh 5 tap
PER
BT Interference SIR= -20 dB
No Interference
BT Interference SIR= -10 dB
Bluetooth Interference SIR=0 dB
BT Interference SIR=10 dB
BT Interfernce SIR=20 dB
SNR
J. Terry, Nokia

12. Scenario #2 Environment: 1 BT pico net with Erasures
May 2001
Scenario #2
Environment: 1 BT pico net with Erasures
Channel: 5 tap Rayleigh channel
SIR: [20, 10, 0, -10, -20]
Data Rate: 24 Mbps
J. Terry, Nokia

13. 24 Mbps PER Simulation May 2001 J. Terry, Nokia 10 11 12 13 14 15 1617 18 -3 -2 -1
SNR
PER
Packet Error Rate, IEEE802.11a 24Mbit mode, Rayleigh 5 tap
BT Interference SIR= -20 dB
BT Interference SIR= -10 dB
BT Interference SIR= 0 dB
BT Interference SIR= 20 dB Perfect Sync
BT Interference SIR= 20 dB
No Interference
J. Terry, Nokia

14. Channel: 5 tap Rayleigh channel
May 2001
Scenario #3
Environment: 1 BT pico net comparison of erasure w/perfect and imperfect synchronization
Channel: 5 tap Rayleigh channel
SIR: [10, 0]
Data Rate: 24 Mbps
J. Terry, Nokia

15. 24 Mbps PER Simulation May 2001 J. Terry, Nokia 10 11 12 13 14 15 1617 18 19 20 -2 -1
SNR
PER
Packet Error Rate, IEEE802.11a 24Mbit mode, Rayleigh 5 tap
BT Interference SIR= -10 dB Perfect Sync
BT Interference SIR= -10 dB
BT Interference SIR= 0 dB Perfect Sync
BT Interference SIR= 0 dB
J. Terry, Nokia

16. May 2001
Scenario #4
Environment: 1 BT pico net comparison with and without Erasures
Channel: 5 tap Rayleigh channel
SIR: [20, 0, -20]
Data Rate: 24 Mbps
J. Terry, Nokia

17. 24 Mbps PER Simulations May 2001 10 11 12 13 14 15 16 17 18 19 20 SNR-2 -1
SNR
PER
Packet Error Rate, IEEE802.11a 24Mbit mode, Rayleigh 5 tap
BT Interference SIR= -20 dB w/Erasures
BT Interference SIR= -20 dB
BT Interference SIR= 0 dB w/Erasures
BT Interference SIR= 0 dB
BT Interference SIR= 20 dB w/Erasures
BT Interference SIR= 20 dB
J. Terry, Nokia

18. Scenario #5 Environment: 1 and 3 BT pico net comparison
May 2001
Scenario #5
Environment: 1 and 3 BT pico net comparison
Channel: 5 tap Rayleigh channel
SIR: [20, 0, -20]
Data Rate: 24 Mbps
J. Terry, Nokia

19. PER vs # BT Interference
May 2001
PER vs # BT Interference 10 11 12 13 14 15 16 17 18 19 20 -2 -1
SNR
PER
Packet Error Rate, IEEE802.11a 24Mbit mode, Rayleigh 5 tap
BT3 Interference SIR= -20 dB
BT Interference SIR= -20 dB
BT3 Interference SIR= 0 dB
BT Interference SIR= 0 dB
BT3 Interference SIR= 20 dB
BT Interference SIR= 20 dB
J. Terry, Nokia

20. Scenario #6 Environment: 1 BT pico net Channel: 5 tap Rayleigh channel
May 2001
Scenario #6
Environment: 1 BT pico net
Channel: 5 tap Rayleigh channel
SIR: [20, 10, 0, -10, -20]
Data Rate: 48 Mbps
J. Terry, Nokia

21. 48 Mbps PER Simulation May 2001 J. Terry, Nokia 19 20 21 22 23 24 2526 27 10 -3 -2 -1
SNR
PER
Packet Error Rate, IEEE802.11a 48Mbit mode, Rayleigh 5 tap
BT Interference SIR= -20 dB
No Interference
BT Interference SIR= -10 dB
Bluetooth Interference SIR=0 dB
BT Interference SIR=10 dB
BT Interfernce SIR=20 dB
J. Terry, Nokia

22. May 2001
Conclusions
Bluetooth interference severely degrades the PER performance of OFDM systems for SIRs of 10 dB and smaller.
An error floor equals to the probability that a BT hops in-band occurs.
Erasures provide very little additional protection when all the receiver algorithms are used.
Higher data rates such as 48 Mbps are more susceptible to the interference than lower rates.
More sophiscated interference suppression techniques are needed to improve performance.
J. Terry, Nokia