14653_wifi vs Bluetooth

8/4/2019 14653_wifi vs Bluetooth

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Paper Presentation

Wi-Fi (802.11b) and Bluetooth:

Enabling CoexistenceJim Lansford, Ron Nevo, and Brett Monello

CSC8900

Presented by: Tu Tran


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Presentation Outline

Introduction

Overview of Wi-Fi Bluetooth Technologies

Issues of coexistence

Experimental Results

Solutions to coexistence issues Questions or Comments


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Introduction

Two prominent wireless technologies:

WPAN: Wireless Personal Area Networking

supports a short range (10m), implemented in Bluetooth applications such as wireless headsets, PDAs, keyboards,

mice, etc.

WLAN: Wireless Local Area Networking

supports wider range (100m), designed in Wi-Fi (802.11b)

applications such as wireless routers, wireless cards,wireless printers, etc.


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Introduction (contd)

WPAN & WLAN are complementary

Collocation of Wi-Fi and Bluetooth become

increasingly significant.

Coexistence: wireless systems can be

collocated without significantly impacting

the performance of either


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Overview of Bluetooth and Wi-Fi

Characteristics Bluetooth

a cable replacement radio frequency technology: lowcost, modest transfer rate, and short range.

supports piconets of up to eight active devices withthree synchronous connection-oriented links /asynchronous connectionless. piconet: an ad-hoc computer network

PHY uses frequency-hop-ping spread spectrum(FHSS) at 1600hops/s

data transfer rate 11Mb/s or higher


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Overview of Bluetooth and Wi-Fi

Characteristics (contd) Wi-Fi (802.11b) supports multipoint networking

data types as broadcast, multicast, unicast MAC address built-in, allowing unlimited

number of devices to be active

PHY uses direct-sequence spread spectrum

Both Wi-Fi and Bluetooth share the samefrequency band, 2.4Ghz


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Issues of Coexistence

Both Wi-Fi & Bluetooth operate at the same timewithin the same frequency band, they willinterfere with each other, creating in-bandcolored noise.

The inference is called noise

Noise: in-band noise & out-of-band noise

in-band noise: the transmitter uses the undesiredenergy in frequencies to transmit the desired signal.

out-band noise: the transmitter does not use.


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Issues of Coexistence (contd)

white noise: interference from multiple sourceswithout their coordination.

colored noise: interference transmitted by two

intentional radiators, behave in time & frequency Occurrence of the interference:

An 802.11b receiver senses both Bluetooth and802.11b signals at the same time. The effect happens

when Bluetooth signal is within the 22-MHz wide passband of the receiver.


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Issues of Coexistence (contd)

A Bluetooth receiver senses both 802.11band Bluetooth signals at the same time. The

inference occurs when the 802.11b signal iswithin the Bluetooth receiver.

The interference reduces the performanceof data transfer rate and packet lost.


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Experimental Results


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Recommended Solutions

Usage and Practices: No coexistence

Technical Approaches:

General System Approach: lowering the power levels in thecollocated Bluetooth node would lessen the interference impacton Wi-Fi.

Driver Layer: using software layers above the MAC to switch thetwo technologies

MAC layer: listen-before-talk functions Bluetooth is difficult to

detect Wi-Fi operations. Physical Layer: via design decisions

Alternating Frequency bands: separating two different frequency.


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Questions or Comments?

Thank you!

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14653_wifi vs Bluetooth