1 Solving the Interference Problem due to Wireless LAN for Bluetooth Transmission Using a Non- Collaborative Mechanism Yun-Ming, Chiu 2005/6/09
2 Outline Overview Survey of Bluetooth Structure of Bluetooth Connection of Bluetooth Device Packets of Bluetooth Co-exist with WLAN Conclusion
3 Overview Wireless PAN (personal area network) Low power Low coverage Low data rate Bluetooth, UWB Wireless LAN (Local area network) High power High coverage High data rate b, g
4 Overview Application of Bluetooth
5 Overview Structure of WLAN Infrastructure Ad-hoc
6 Survey of Bluetooth The original idea behind Bluetooth technology In 1994, when Ericsson Mobile Communications began to study a low-power consumption system to substitute for the cables in the short-range area of its mobile phones and relevant accessories. In 1998 Ericsson, Nokia, IBM, Toshiba, and Intel formed the Bluetooth Special Interest Group (SIG). the first release of the Bluetooth protocol is in 1999 In 2000, the first Bluetooth headset, from Ericsson, appeared on the market.
7 Survey of Bluetooth March 2002, the IEEE working group has adopted the work done on Bluetooth and made it an IEEE standard, Bluetooth is currently at version 1.2
8 Structure of Bluetooth (1)
9 Structure of Bluetooth (2) Block of Bluetooth
10 GFSK Modulation De-modulation
11 SPEC. for Bluetooth Frequency band 2.4GHz Modulation GFSK (Gaussian-shaped, binary FSK) Multiplexing FHSS (Frequency Hopping Code Division Multiple Access) Data Rate 1Mb/s (730Kb/s) TDD
12 Frequency Hopping (1) Frequency Hopping Code Division Multiple Access Baseband 2.4G Bandwidth 1M 79 Frequency Hopping Carriers (Hopping channel)
13 Frequency Hopping (2) Packet time 625 s Hopping rate 1/625 s =1600 times/sec One frequency for a timeslot (slow hopping)
15 Typical output power Class 1 Class 2 Class 3 Power 100mW 2.5mW 1mW Range 100m 10m NA
16 Connection of Bluetooth (1) More then two Bluetooth device could establish a Piconet. In a Piconet could have 1 Master, 7 active slave, and 256 Parked slave
17 Connection of Bluetooth (2) Scatternet Piconet could combine to a Scatternet through a slave device.
18 Connection of Bluetooth (3)
19 PHYSICAL LINKS SCO Link (for Voice) ACL Link (for Data)
20 Packets of Bluetooth (1) Standard packet format Access Code Packet Header Payload
21 Packets of Bluetooth (2) Access Code There are three different types of access codes defined: Channel Access Code (CAC) Device Access Code (DAC) Inquiry Access Code (IAC)
22 Packets of Bluetooth (3) PACKET HEADER The header contains link control (LC) information and consists of 6 fields: AM_ADDR: 3- bit active member address TYPE: 4-bit type code FLOW: 1-bit flow control ARQN: 1-bit acknowledge indication SEQN: 1-bit sequence number HEC: 8-bit header error check
23 Packets of Bluetooth (4) Payload According data length, there are three types of Payload format.
24 Co-exist with WLAN Bluetooth and WLAN share the same 2.4 GHz ISM band( ghz). Resulting in an interference problem between them. There two Mechanism to solve the problem. Collaborative mechanism Non-Collaborative mechanism
25 Collaborative mechanism (1) Means that there are Bluetooth and WLAN co-exist in a device.
26 Collaborative mechanism (2) Time Division (Control by CU)
27 Collaborative mechanism (3) Bluetooth MAC
28 Issues In real case, there are several WLAN and Bluetooth device in an office
29 Non-Collaborative mechanism (1) Adaptive packet size Adaptive hopping Adaptive Power control Need use feedback algorithm
30 Non-Collaborative mechanism (2) -Adaptive packet size Depends on CIR (Carrier to interference Ratio)
36 Non-Collaborative mechanism (3) -Nulling A. Soltanian and R. E. Maryland, b deterministric frequency nulling to mitigate Bluetooth interference, IEEE /079, Jan Bluetooth will stop transform data while WLAN transits.
37 Conclusion The Non-Collaborative mechanism could reduce the interference effetely. The data rate are different between slave device, because they have difference distance to master device. We must think about that several WLAN in a wireless area in the future.