Introduction to Bluetooth Kirsten Matheus The idea behind Bluetooth The problems when trying to realize the idea The solutions used in Bluetooth How well the solutions work 12.06.2003 1
he Idea Behind Bluetooth iversal, short range cable replacement upports speech and data and can be used (almost) worldwide without the need of an infrastructure digital camera car laptop printer mobile phone GSM digital pen headset mobile phone etc. Seite 2 12.06.2003
luetooth has to Function in the harsh conditions of the wireless transmission medium Widely used Only with many BT products there is the choice to connect freely as you like Compatible So that the connections may be independent of manufacturer Seite 3 12.06.2003
easures to Ensure Distribution: Specification by industrial consortium Ericsson, IBM, Intel, Nokia and Toshiba founded the BT SIG in 1998 Fast because few partners mean fewer opinion that have to be agreed upon Open to be used by anyone No fees for key patents Technical side comparably cheap to realise Chip price today under 5$US Placed in unlicenced frequency band (ISM at 2.4GHz) Almost worldwide deployment without the need to pay licence fees Seite 4 12.06.2003
easures to Ensure Compatability: Qualification procedure for every BT product Specific profiles for each application Generic Access Profile TCS-BIN-based Profiles Service Discovery Application Profile Cordless Phone Profile Intercom Profile Serial Port Profile Dial-up Networking Profile Fax Profile Generic Object Exchange Profile File Transfer Profile Headset Profile Object Push Profile LAN Access Profile Synchronization Profile Seite 5 12.06.2003
onnection Set-up Example inq.scan page scan inquiry paging page inq.scan scan inquiry paging inquiry paging inq.scan page scan FHS inquiry paging inquiry paging L2CAP attributes request SDP connection for for FT FT inq.scan page scan inq.scan page scan inq.scan page scan inq.scan page scan page inq.scan scan Laptop knows has it all has information found a printer it and needs. how It can to communicate disconnect to with check it, for but it other does devices not know in the yet area, what or profiles it can the printer ask the user supports whether to print on this printer or it can start the printing process inquiry paging inquiry paging inquiry paging Seite 6 12.06.2003
echnical Data Organized in packets access code 72 header 54 payload 16 2736 GFSK modulated data at 1Mbps (1bit ^ = 1symbol) 79 carriers of 1MHz 1mW transmit power (100mW optional) slave 1 slave 3 Master/Slave concept (piconets) Organizes the piconet of up to 7 slaves Determines the hop sequence of FH/TDD-scheme master slave 2 Seite 7 12.06.2003
DD/FH Channel f f f f 3 64 17 78 M t S 1 t S 2 Slot = 625 µ s t Frame = 1.25 ms Seite 8 12.06.2003
CL Packets (for Data) (A)symmetric, asynchronous services Because data allows no bit errors, ARQ scheme Polling scheme for slaves Quality of data link: Burst requires retransmission Retransmitted bursts are counted in the burst failure rate BFR Causes delay Payload can be used with optional FEC coding (rate 2/3) Up to 10% packet retransmissions ok Seite 9 12.06.2003
CL Packet Types short packets are less sensitive to interference have a smaller transmission rate Seite 10 12.06.2003
CO Packets (for Speech) Symmetric, synchronous services Speech allows no delay Slot reservation at fixed intervalls Speech quality: Burst is replaced with a 01 bit pattern Replaced bursts are counted in the frame erasure rate FER Distorts the voice Payload (incl. bit errors) is forwarded to the CVSD decoder Bursts with too many bit errors are counted in the unsat. payload rate UPR Causes crackling noise ACL: Up to 10% packet retransmissions ok Payload can be used with optional FEC coding Combined in the unsat. burst rate FER+UPR=UBR 1-2% average UBR per link unacceptable Seite 11 12.06.2003
CO Packet Types! HV1 causes three times and HV2 causes 1.5 times! more interference than HV3 but only their! payloads receives more protection Seite 12 12.06.2003
acket Types in Overview Type FEC symmetric asymmetric traffic DM1 2/3 108.8 kbit/s 108.8 kbit/s 108.8 kbit/s DM3 2/3 258.1 kbit/s 387.2 kbit/s 54.4 kbit/s DM5 2/3 286.7 kbit/s 477.8 kbit/s 36.3 kbit/s DH1-172.8 kbit/s 172.8 kbit/s 172.8 kbit/s DH3-390.4 kbit/s 585.6 kbit/s 86.4 kbit/s DH5-433.9 kbit/s 723.2 kbit/s 57.6 kbit/s HV1 1/3 64 kbit/s HV2 2/3 64 kbit/s HV3-64 kbit/s Speech Data Seite 13 12.06.2003
ixed Link Example MASTER SCO ACL SCO ACL ACL SCO SCO ACL SLAVE 1 SLAVE 2 SLAVE 3 Seite 14 12.06.2003
nterference Robustness To interfere with each other different devices have to be used: In the same location At the same time } Depends on user scenario On the same frequency Depends on specification Other Bluetooth piconets Microwave ovens IEEE 802.11b WLAN other Seite 15 12.06.2003
nterference Robustness slave 3 master master slave 3 slave 1 slave 2 slave 1 slave 2 not like cellular systems blocking, adjacent channel effects hit or miss (interference) Seite 16 12.06.2003
nterference in Cellular Systems MT 1 BS MT 2 MT 3 MT 3 BS MT 2 BS MT 1 MT 2 MT 1 MT 1 MT 1 BS BS MT 3 MT 3 MT 1 BS MT 2 MT 2 MT 2 Minimum distance to next co-channel interferer Seite 17 12.06.2003
erformance in Case of luetooth interference Radio Network Simulations (in MATLAB) Many simultaneous BT connections Propagation Model Distant dependent fading Shadowing Multipath fading Traffic Models Www-traffic (av.generated data 33.2kbps) Positioning Model 10m by 20m room Uniform distribution of masters Slaves at av. 2m to master in 2-dim Gaussian distribution Seite 18 12.06.2003
erformance in Case of luetooth Interference (contd) Average throughput [bits/s] Number of concurrent WWW-sessions At 100 concurrent WWW-sessions only 5% throughput degradation Seite 19 12.06.2003
erformance in Case of icrowave Oven Interference Interference of microwave oven depends on: Type (residential or commercial) Oven brand Oven load Position of the receiver towards the oven (in front of window worst radiation) Distance between receiver and oven Seite 20 12.06.2003
erformance in Case of icrowave Oven Interference (contd) Seite 21 12.06.2003
erformance in Case of icrowave Oven Interference (contd) 9ms (of 20ms mains power cycle) Seite 22 12.06.2003
erformance in Case of icrowave Oven Interference (contd) Simulation Parameters: Distance of BT to microwave oven Distance between BT units As expected: The closer the Bluetooth units to each other and the further away they are from the microwave oven the better Data (ACL) transmission is uncritical Speech (SCO) transmission Not critical in PAN environments Degradations will occur only at unfavourable distance ratios Even then the degradation is smooth and Comprehensibility remains Seite 23 12.06.2003
erformance in Case of EEE 802.11b Interference 02.11b SSS 2MHz 00mW -13-20 -30-40 -50 main lobe Bluetooth FH 79x1MHz 1mW first -60 side lobe first side lobe -70 second side lobe and rest -80 second side lobe and rest -90-100 -110-113 Cen ter 2.44 GHz 8 MHz/ Span 80 MHz In principle overlap, actual impact (of 802.11b on BT or of BT on 802.11b) depends on location of units Seite 24 12.06.2003
17MHz at 20dBm erformance in Case of EEE 802.11b Interference (contd) f 45 40 35 30 25 20 t 12.06.2003
erformance in Case of EEE 802.11b Interference (contd) Seite 26 12.06.2003
erformance in Case of EEE 802.11b Interference (contd) Voice Audible degradations unless BT-link <0.5m Data Up to 5m BT-link PLR always smaller than 20% PLR<10% for BT-link<2m and more than 5m distance to WLAN Seite 27 12.06.2003
uture Developments Bluetooth Specification 1.2 Improvements and additions to Spec. 1.1 Adaptive Frequency Hopping Improvements of voice link QoS Further profiles (Hands-free, SIM-access etc) Bluetooth Version 2.0 High rate mode with 10-fold throughput Downward compatible Seite 28 12.06.2003
Summary The idea and basic principles behind Bluetooth Universal cable replacement Compatibility and world wide deployment feasable Master/Slave concept FH/TDD Different conceptions of speech and data quality Interference Robustness Bluetooth to Bluetooth Microwave oven to Bluetooth IEEE 802.11b to Bluetooth 12.06.2003 29 Future Developments
Kommunikationscharakteristika der Dienste: Dienst Charakteristik Anforderung Telefonie Sprachübertragung 64Kbit/s; isochron SIM Zugriff Signalisierung Semiechtzeit Flashen der Steuergerät-SW Daten upload Hohe Datensicherheit (Fehlerbehebung) Infotainment Streaming Semiechtzeit Datenübertragung File Transfer Hohe Datensicherheit (Fehlerbehebung) Seite 30 12.06.2003
Bluetooth Protokolle und Profiles... Profiles Profile 1 Profile 2 Profile 3 Profile 4 Profile 5 Profile 6 Profile 7 API OBEX PPP/TCP/IP AT-C SDP Database RFCOMM TCS SDP L2CAP Audio Protocol Stack HCI Host Bus Driver HCI Chip ACL Base Band SCO Radio Link Manager Firmware Hardware Seite 31 12.06.2003
System Architecture The Radio, Baseband and Link Manager are on firmware. The higher layers could be in software. The interface is then through the Host Controller (firmware and driver) The HCI interfaces defined for Bluetooth are UART, RS232 and USB. Control SDP Applications IP RFCOMM Data L2CAP Audio Link Manager Baseband RF Bluetooth Protocol Stack Seite 32 12.06.2003
Bluetooth defined Profiles Profile dependencies. Generic Access Profile TCS-BIN-based Profiles Service Discovery Application Profile Cordless Phone Profile Intercom Profile Serial Port Profile Dial-up Networking Profile Fax Profile Generic Object Exchange Profile File Transfer Profile Headset Profile Object Push Profile LAN Access Profile Synchronization Profile 12.06.2003 33