BLUETOOTH TECHNOLOGY Coexistence Of Bluetooth And Wi-Fi Presented by: JIGAR A. SHAH K.K. Wagh College of Engg. Jigar_a_shah83@yahoo.com YUGA SOMVANSHI

Coexistence scenario

Overview of Wi-Fi (802.11b) It is specification for WLAN Wireless Ethernet Compatibility Alliance certify product as Wi-Fi compatible Data transmission on BPSK and QPSK Data transmission at 11 Mbps Direct Sequence Spread Spectrum (DSSS) Devices are classified as Access Point and Station Range of data transmission up to 100m

Frequency occupancy of three Wi-Fi Networks

Overview of Bluetooth It is WPAN technology Data transmission on GFSK Hops at 1600Hz over 79 channels of 1MHz Uses Frequency Hopping Spread Spectrum (FHSS) Devices are classified as Master and Slave Generally used as cable replacement technology Communication range up to 10m Data transmission at 724Kbps

Bluetooth frequency occupancy example

What is coexistence ? “Coexistence”, the ability for multiple protocols to operate in the same frequency band without significant degradation to either’s operation 2.4GHz ISM band is 83.5MHz wide with lower limit from 2.400GHz and higher limit from 2.4835GHz Both Bluetooth and Wi-Fi utilizes same 2.4GHz ISM band Bluetooth device hops over 79MHz channel and Wi-Fi requires 16MHz bandwidth – chances of interference are very high Wi-Fi and Bluetooth are complementary rather than competing

TESTING

Testing Notation

Wi-Fi throughput – baseline performance

Bluetooth throughput - baseline

Wi-Fi performance with Bluetooth interference – Testing setup Test -1 with Bluetooth Test – 2 with Bluetooth at 10m

Wi-Fi performance with Bluetooth interference

Bluetooth performance with Wi-Fi interference

Methods for Improved Coexistence MAC layer switching Adaptive Fragmentation for Wi-Fi Networks Transmit Power control Dynamic Channel Selection for Wi-Fi Network Adaptive Frequency Hopping for Bluetooth Networks

FCC Regulations for transmitting power Section 15.247 of FCC regulation specifies high power transmission for FHSS and DSSS Section 15.247a of FCC regulations limits high power transmitters up to 1 Watt for DSSS and FHSS Minimum No. of channel to be hopped was 75 in 2002 To limit transmission power FCC changed min. number of channel to be hopped to 20 channels

Factors on which determination of best channel depends: Packet error rate Channel noise Channel multipath and intersymbol interference Received signal strength

Wi-Fi and Bluetooth Interference

Adaptive Frequency Hopping (AFH) Example

AFH (Adaptive Frequency Hopping)

Changes in Bluetooth 1.2 specification AFH is specified in Bluetooth 1.2 specification Base band: Updated base band describes the algorithm used for generating an adapted hop channel set LMP (Link Manger Protocol): it is updated with new message for communicating the bit mask that identifies which channel may be used and which are to be avoided The bit mask consist of 79 bits which gives detail about which channel is to be used and unused HCI (Host Controller Interface): it includes two new commands ; First to exclude channels from list Second one to read channel map currently in use

Limitation of AFH Not suitable for collocated Wi-Fi and Bluetooth devices, Effectiveness depends on antenna isolation, transmit power of devices and the sensitivity of receiver Requires antenna isolation Cannot be used if either master or slave does not support it Not effective for Bluetooth 1.1 compatible devices change

AFH is used with other coexistence technology UltimateBlue™ by siliconwave Intel Wireless Coexistence System (WCS) Blue802™ technology

Coexistence Technique Comparison by Design Parameters

Standardization Activities IEEE 802.15 WPAN has formed different task groups: TG1 (802.15.1) : reformulating BT 1.x spec into IEEE standards TG2 (802.15.2) : Recommend practices coexistence of wireless devices operating in the 2.4GHz band Bluetooth SIG coexistence Working Group is established to make changes in Bluetooth standards

References Andrew Tanenbaum: Computer networks, fourth edition Douglas Comer: Computer Networks and Internet Jennifer Bray, Charles Struman: Bluetooth-connect without cable

Web - References www.ti.com/wlan (Texas Instrument) www.wimaxforum.com www.alcatel.com www.stdsbbs.ieee.org/groups/802/11 www.bitpipe.com www.interop.com www.ieee802.org/15 www.bluetooth.org www.codebluecommunication.com www.3com.com www.trillium.com www.motorola.com www.itpapers.com www.siliconwave.com www.wi-fi.org www.mobilian.com www.intel.com

Thank You! Questions?