Bluetooth technology introduction and ecosystem
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The document discusses Bluetooth technology and related topics. It provides an overview of Bluetooth SIG, the development and adoption of Bluetooth specifications, and key Bluetooth concepts like generic attribute profile (GATT) and attribute protocol (ATT). It also summarizes Nanoleq's work in developing e-textile solutions using multiple Bluetooth services.
Bluetooth technology introduction and ecosystem
- 1. Reconnect to your body. Know your vitals. Niclas Granqvist, CTO [email protected]
- 2. • Bluetooth SIG • Bluetooth technology • Markets and Global Success • Marketing • What You Must • LL – Link Layer • L2CAP – Multiplexer • ATT – Attribute Protocol • GATT – Generic Attribute Profile • GAP – Generic Access Profile • DIS – Device Information Service • Bluetooth LE Health Services • Qualification • What else does Bluetooth provide? • What is Nanoleq doing? Content
- 3. • Founded September 1998 • Bluetooth SIG is worlds largest Special Interest Group: ~36 000 member companies • Jaap Haartsen, inventor • 2 Membership levels adopters(free) and associate • Promotor level is for BoD companies: Microsoft, Intel, Apple, Ericsson, Motorola, Nokia and Toshiba • A few associates that are selected among member companies • Bluetooth SIG is run as a “not-for-profit” Bluetooth SIG
- 4. Markets
- 5. Markets
- 6. Bluetooth Low Energy is the most successful low power radio technology ever launched shipping in billions. The reason was the combination with BR/EDR Global Success!
- 7. The members develop the specifications and the SIG adopts the spec. • Adoption means that Bluetooth SIG takes ownership of the specification • Bluetooth SIG immediately licenses it back to the member on the condition that you show interoperability by going through a qualification program and paying a listing fee • The members cross license. You can not sue for another company using your IP in the spec. Patents can be used passively for defence • The Bluetooth license is royalty free, unlimited, perpetual and irrevocable • The specification development is the heart of Bluetooth • The Bluetooth qualification program is maybe the most important service as each product must pass to be qualified • A significant part of the Bluetooth is marketing promotion but also promotion of members solutions. Development model
- 8. • You must be a member of the SIG • You must ensure that the product is properly qualified and listed • You must follow the Bluetooth brand guidelines Simple, Secure and Everywhere What you must
- 9. • Bluetooth is one of the most recognized brands in the world • Correct marketing is important for the message and integrity of the brand • Read the Bluetooth brand guidelines before making the product design Bluetooth Brand Marketing
- 10. • Members develops the Bluetooth specifications • 1.0, 1.0b, 1.1, 1.2, 2.0, 2.1, 3.0, 4.0, 4.1, 4.2, 5.0, 5.1, 5.2, 5.3 Core specfications • Release cadence has increased over past years • Rule of thumb: Major version change means new HW. Minor implies a software update may be enough • Backwards compatible • Core specification (BR/EDR and LE) • In total ~5 different radio specifications • 2 Mbits e.g. useful for FW updates and music • 1 Mbits, best range and general performance • Long Range: 500 & 125 kbits: > 600 meters in open air • Specifications to support applications • Bluetooth LE services and profiles • Bluetooth classic profiles and protocols • Bluetooth Mesh and mesh models • Tests for qualification Bluetooth SIG spec dev. Core spec 5.2 3256 pages 7142 Shalls 766 Shoulds + 2020 Mays ============= 9 928 conditions to remember!
- 11. Bluetooth is a hierarchal stack • Stack divided into logical layers • Each layer has clear responsibilities • Mixing layers is a “layer violation” • Layers should not know of each other • Layers have feature bits for future enhancements The packet is the sum of the layers Advantages • Layers can evolve independently • Layers can be added or removed Hierarchal stacks Application Services Data GATT/ATT MUX – L2CAP LINK LAYER Preamble Acc. adr LL LL L2CAP ATT Data BLE layout Radio
- 12. OSI model and Bluetooth Android and iOS API integration BLE Profile BLE Application stack BLE Service / GATT ATT Protocol / L2CAP BLE Link Layer BLE radios BLE Mesh network Mesh transport Models H o s t C o n t r o l l e r BLE is point to point No sessions
- 13. (Borrowed from Alpwise) Notice separation of host and controller Bluetooth LE Stack
- 14. • Low peak currents, coin cell technology • Optimised for small and infrequent data • Cheap and robust, not fast • Cheap, robust and fast. Pick two! • 1 Mbits is fast enough for most simple devices Robustness • Channel hopping to combat WIFI and multipath • Data whitening to optimise receiver performance • Advertisement channels (3) in-between wifi channels • Long CRC (3 bytes) to ensure that bits are correct • Good enough for medical applications • Encryption gurantees integrity • Link layer will retry an unsuccessful transfer • Device address made so as to increase correlation in noise • ATT transport protocol has acknowledgement, if needed • Extended advertising reduces load on current channels BLE Communication System
- 15. • Centrals control connections • Peripheral obey • A device can be master and slave at the same time • You can have many LL state machines • This is all LL terminology. In most cases better to use GAP: Central, Peripheral, Observer and Broadcaster Link Layer State Machine Slave Master Sound, Streaming Data, ECG Find devices Advertising Chains on sec. adv. channels Connection creation Sensor ready For discovery and connection
- 16. • BLE 4.0 was a star topology • BLE >4.1 is scatternet • Advertisements are broadcasts • Connections are unicasts Example: The Polar H10 heart rate sensor can be connected to two masters at the same time Topology M/Sl Sl M M Sl Sl Sl Adv Sc Sc Sc Scatternet: Star: Sl M M Polar H10 Sl Broadcasts
- 17. All data packets are modifications of one basic format. This keeps BLE simple PDU = protocol data unit BLE packet format Allows some time for the AGC to stabilise Address of the device, correlator Data Error check Long range packet 1 Mbit/sec = 1 bit = 1 usec (Symbol time) TERM1,2 are for error correction
- 18. • An advertisement PDU is can be directed or undirected • Undirected = broadcast • Directed = for one special device • Advertisements can be connectable or non-connectable • AD structures encode data using UUIDs BT 5.0 has a new elaborate advertising functions for long range, synch chains, sec. adv. channels etc Advertisement data format
- 20. BLE: GATT Data exchange can start after exchange of one packet. It takes Bluetooth classic average ~100 ms to get to data exchange because “many” protocols must be setup Initiate connection Master Slave
- 21. Once two devices are in a connection, either device can send data. This example shows both devices sending data, for example when the Attribute Protocol does a read request and a read response is returned There are two channel hopping algorithms. The newer channel hopping algorithm is superior Data Exchange
- 22. • Use More Data (MD) bit when more to say • SN, NSN for ack • Lazy ack to save 50% energy MD and SN
- 23. Master or slave can disconnect Disconnect
- 24. If reception stops • The master receives no response • The slave receive no poll package then the link layers will inform the hosts that the a disconnection has occurred. This is called a supervision timeout. Supervision Timeout
- 25. BLE security features BLE has a cryptographic toolbox that allows for various use 1. Encryption (AES-128 bit) (hides message, integrity, authentication of every packet) 2. Authentication 3. Privacy, the ID of the device can be obfuscated. This makes it impossible to scan for BLE devices as the unique device ID is changing periodically 4. Data Signing 5. Authorisation All algorithms are standard algorithms that are well understood!
- 26. L2CAP is a sophisticated data multiplexer • Is part of the host • Provides static and dynamic data streams between hosts • Splits large packets into pieces and moves the parts. • The receiving host reassembles the parts • The unhenhanced ATT bearer is using CID 0x04 that is a static port. This is highly efficient and saves battery L2CAP
- 27. • GATT is a client server architecture, compare to http • Clients collect data • Sensors are services and send notifications with data • The roles are not fixed. The first one issuing a PDU determines the role • A server can handle multiple clients • Decouples development of the two ends • GATT is stateless • GATT services are considered immutable (never change, once deployed) • GATT services are collections of characteristics structured into services • Service UUIDs identify the type of service. A service consist of characteristics • Characteristics return data, e.g. HR and RR • Characteristics have UUID • Another characteristic return the measurement location • BT SIG UUID = 16 bit, company defined 128 bit randomised • Characteristics have operations • Notifications and indications (acknowledged) • Read data • Write data • Special operations for e.g. automation multiple characteristic writes + commit • Characteristics have security e.g. a certain operation may require encryption GATT Server Client Client Client Server
- 28. Generic attribute profile (GATT) • Enable large scale interoperable ecosystems of data • Asynchronous data • Bluetooth has no QoS but it is best effort • Enable applications on phones, watches • Build smarter applications • Be small and efficient • GATT uses a static port (compare to UDP in TCP/IP) and does not need to configure L2CAP. This saves ~6 packets. • GATT discovery and execution is all done using one protocol, ATT protocol • Bluetooth classic needs minimum 2 protocols • The attribute protocol is used throughout BLE. Keep it simple! • GATT is a way to describe structured and unstructured data • Profiles describe use cases (roles, security, advertising etc) GATT Services GATT ATT Profile GAP Use case
- 29. • Used by GATT & higher level profiles to implement services • Can be independently qualified and can be used on it’s own if ever needed ATT (Attribute protocol)
- 30. 1. The first step is always to discover all services • If the GATT database has not changed then this is unnecessary, GATT caching, bonded? • Hash 2. Configure the proper characteristics 3. Enable notifications - Communicate ! Service Discovery
- 31. • Bluetooth 5.2 supports enhanced bearers • The enhanced bearer allows for collections of services • Solves fundamental limitations in ATT for complex multi-service scenarios Service Collections Device 2 Collection 21 Client 1 Collection 22 Service 1 Service 2 Device 1 Collection 11 Client 1 Collection 12 Service 1 Service 2
- 32. Most layers can support company specific information when needed. • L2CAP has dynamic channels • GATT has 128 bits services • Company specific advertisement information As a rule a protocol commands cannot be added in any layer ATT, L2CAP and LL are fixed Company specific info
- 33. All Centrals and Peripherals have a GAP service GAP Service
- 34. It considered good practice to support DIS in every device. Always implement all relevant DIS characteristics Device Information Service
- 35. Reuse GATT services Name Version Year BAT Battery Service 1.0 2011 FTMS Fitness Machine Service 1.1 2017 DIS Device Information Service 1.1 2011 UDS User Data Service 1.1 2019 PAMS Physical Activity Monitor Service 1.0 1.0 2020 HRS Heart Rate Service 1.0 2011 HTS Health Thermometer Service 1.0 2011 PLXS Pulse Oximeter Service 1.0 2015 OTS Object Transfer Service 1.0 1.0 2015 Useful services to promote open data Make your own GATT service if not one of the existing ones.
- 36. Some principles • All products must be qualified • The qualification is validation of design. The required commitment to interoperability goes beyond testing. It must work! • What has been tested does not need to be tested a second time • Changes need to be assessed and tested • Start project using Bluetooth Launch Studio • Download and use PTS for testing • Tip: The testing specifications are very useful when implementing as they list all possible mandatory and optional features explicitly. Study testing specs before implementation! • Fees: Listing fee 8000 USD for adopters for a product family Bluetooth Qualification
- 37. • Long range radio • Stay connected even if phone is far away • Android has fairly good support • Advertising and Extended advertising • Beacons • Used in group training and workwear • Direction finding AoA & AoD (5.1) • Touch and go, integration with NFC • Out of band TKs • Isochronous channels (streaming data: sound, ECG) (5.2) • Can be used for other types of data, too! • LE power control (5.2) – minimises output power in closed loop Other useful core features?
- 38. We are building a ground- breaking e-textile multi service solution for your body! Nanoleq plans eclipses everything the industry has done so far in scope and sophistication What is Nanoleq doing?
- 39. THANK YOU
- 41. Data paths