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Interference of Bluetooth and IEEE 802.11:

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... (0,0) WLAN AP Tx Power 25 mW WLAN Mobile Tx Power 25 mW Bluetooth Master TX Power 1 mW Bluetooth ... Access Point Distance from Bluetooth ... Presentation Outline ... – PowerPoint PPT presentation

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Title: Interference of Bluetooth and IEEE 802.11:


1
  • Interference of Bluetooth and IEEE 802.11
  • Simulation Modeling and
  • Performance Evaluation
  • N. Golmie, R.E. VanDyck and A. Soltanian
  • National Institute of Standards and Technology
  • Gaithersburg, MD 20899
  • USA
  • nada.golmie_at_nist.gov
  • w3.antd.nist.gov

2
Outline
  • Motivation and Objectives
  • Related Work
  • Overview of Bluetooth and WLAN
  • Simulation Modeling
  • Channel, PHY and MAC models
  • Simulation Scenario
  • Simulation Results
  • Summary and Current Work

3
Motivation and Objective
  • Interference in the 2.4 GHz ISM Band Bluetooth,
    HomeRF, IEEE 802.(11,11-b) devices operating in
    the same environment may lead to significant
    performance degradation in WPAN and WLAN
    services.
  • Our goal is to evaluate the impact of
    interference on Bluetooth and WLAN performance
    using detailed MAC and PHY layer simulation
    models developed to accurately reflect the
    interference environment.

4
Related Work on Interference Evaluation
  • Analytical results based on a probability of
    packet collision
  • C. F. Chiasserini, R. Rao, Performance of IEEE
    802.11 WLANs in a Bluetooth Environment, IEEE
    Wireless Communications and Networking
    Conference, WCNC 2000, Chicago IL, September
    2000.
  • S. Shellhammer, Packet Error Rate of an IEEE
    802.11 WLAN in the Presence of Bluetooth, IEEE
    802.15-00/133r0, Seattle WA, May 2000.
  • N. Golmie and F. Mouveaux, Interference in the
    2.4 GHz Band Impact on the Bluetooth MAC Access
    Protocol, Proceedings of ICC01, Helsinki,
    Finland, June 2001.
  • Experimental measurements
  • A. Kamerman,Coexistence between Bluetooth and
    IEEE 802.11 CCK Solutions to avoid mutual
    interference, IEEE 802.11-00/162r0, July 2000.
  • I. Howitt et. al., Empirical Study for IEEE
    802.11 and Bluetooth Interoperability, IEEE
    VTC2001, May 2001.
  • D. Fumolari, Link Performance of an Embedded
    Bluetooth Personal Area Network, Proceedings of
    IEEE ICC01, Helsinki Finland, June 2001.
  • Simulation Modeling
  • S. Zurbes et.al., Radio network performance
    performance of Bluetooth, Proceedings of ICC00,
    New Orleans, LA, June 2000.
  • J. Lansford,et.al., Wi-Fi (802.11b) and
    Bluetooth Simultaneous Operation Characterizing
    the Problem,in Mobilian white paper,
    www.mobilian.com, September 2000.

5
Bluetooth Baseband
6
WLAN MAC
7
Bluetooth vs 802.11 Specifications
  • Bluetooth
  • 1 Mbits/s data rate with TDMA structure (polling)
  • Frequency hopping on a packet basis
  • 625 us slot size, 1 MHz channel
  • Approximately 10 m range
  • 1 mw to 100 mw Transmitter Power
  • Low Cost Radio Receivers
  • Initially designed for one hop operation
  • 1 Master and up to 7 Slaves
  • Scatternets to allow multiple hop networks
  • Voice (SCO) and data links (ACL)
  • IEEE 802.11
  • 1 and 11 Mb/s
  • Direct Sequence Spread Spectrum
  • Complementary Code Keying for the 11 Mbits/s.
  • Carrier Sense Multiple Access with Collision
    Avoidance
  • Also virtual carrier sense using request-to-send
    (RTS) and clear-to-send (CTS) message
  • Range on the order of 100 m
  • Up to 1 W Transmitter Power

8
System Simulation Modeling
Bluetooth Baseband
Bluetooth Baseband
MAC/PHY Interface
1010100101010110
1010100101010110
Channel Propagation Model
BT Packet
WLAN Packet
Detailed DSP Transmitter and Receiver
Simulation Models
WLAN MAC
WLAN MAC
BER3
BER1
BER2
MAC/PHY Interface Parameters Desired Signal
Packet Type, Power, Frequency, distance (tx,
rx) Interference Packet List Type, Power,
Frequency, distance (tx, rx), Time Offset
9
Channel Modeling
  • Additive White Gaussian Noise, multipath fading
  • Path loss model
  • Received power and SIR depend on topology and
    device parameters

10
Physical Layer Modeling
  • DSP based implementation of transceivers
  • Design using typical parameters (goal is to
    remain non-implementation specific)
  • Bluetooth
  • Non-coherent Limiter Discriminator receiver,
    Viterbi receiver with channel estimation and
    equalization
  • IEEE 802.11
  • Direct Sequence Spread Spectrum (1 Mbits/s)
  • Complementary Code Keying (11 Mbits/s)
  • Frequency Hopping (1 Mbits/s)

11
MAC Modeling
  • MAC behavioral implementation for Bluetooth and
    IEEE 802.11 (connection mode)
  • Frequency hopping
  • Error detection and correction
  • Different error correction schemes applied to
    packet segments (Bluetooth)
  • FCS (802.11)
  • Performance statistics collection
  • Access delay, packet loss, residual error,
    throughput

12
Simulation Scenarios
Impact of WLAN Interference on Bluetooth
Performance
Impact of Bluetooth Interference on WLAN
Performance
WLAN AP Tx Power 25 mW
(0,15)
Traffic Distribution for WLAN and BT (LAN
Traffic) Offered Load 30 Of Channel
Capacity Packet Size Geometric Distr.
Mean 368 bytes
Data
ACK
Data
ACK
(0,d)
WLAN Mobile Tx Power 25 mW
Statistics Collection Points
Bluetooth Master TX Power 1 mW
Data
(0,0)
(1,0)
Bluetooth Slave, Tx Power 1 mW
13
Impact of Interference on Packet Loss Bluetooth
and WLAN (11 Mbits/s)
14
Impact of Interference on MAC Access
DelayBluetooth and WLAN 11 Mbits/s
15
Impact of Interference on Packet Loss Bluetooth
and WLAN (1 Mbits/s)
16
Impact of Interference on MAC Access
DelayBluetooth and WLAN 1 Mbits/s
17
Impact of Interference on Number of Errors in BT
Voice Packets
18
Summary
  • Developed detailed MAC and PHY simulation
    platform to study the impact of interference in a
    closed loop environment.
  • Obtained simulation results for mutual
    interference scenario.
  • Performance depends on accurate traffic models
    and distributions.
  • Scenarios using Bluetooth voice traffic represent
    the worse interference cases (up to 65 of WLAN
    packets lost).

19
Current Work
  • Evaluate the impact of interference for other
    scenarios including
  • Bluetooth, and WLAN Frequency Hopping systems.
  • Multiple node scenarios
  • Higher layer traffic models (TCP/IP)
  • Devise and evaluate coexistence mechanisms
  • Packet scheduling
  • Frequency nulling
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