Bluetooth Technology Overview

Bluetooth: Technology and Applications

• Bluetooth is one of the most popular short-range wireless communication standards, known as IEEE 802.15.1.
• It is maintained by the Special Interest Group (SIG)
• Bluetooth devices are ubiquitous, including cellphones, wireless mice/keyboards, smartwatches, earphones, and iBeacons.

Bluetooth: The Name

• The name Bluetooth comes from Harald Gormsson (935-985/6).
• Also known as Harald Blåtand (Harald Bluetooth).
• He liked to eat blueberries.
• He unified Norway, Sweden, and Denmark.
• The name reflects his eloquence and communication skills.

Bluetooth: Born

• Bluetooth's invention was in 1994 by Ericsson.
• A wireless alternative for RS-232 cables.
• Developed in 1997-1998 by Ericsson, Nokia, Toshiba, IBM, and Intel.
• Versions 0.7 and 0.8 were proposed.
• The Special Interest Group (SIG) was founded in 1999.
• Microsoft, Motorola, Samsung, and Lucent joined with SIG.
• Bluetooth 1.0 was published then.

Bluetooth: The Chronicle

• Bluetooth 1.0 (1998.10-2003.11): Base Rate, 1 Mbps data rate. V1.0 draft, v1.0A published '99.7, v1.0B enhanced interoperability, v1.1 enhanced IEEE 802.15.1 compatibility, v1.2 enhanced compatibility.
• Bluetooth 2.0 + EDR (2004.11-2007.7): Enhanced Data Rate; higher ordered modulation for data payload, 2 Mbps or 3 Mbps physical data rate, v2.0, v2.1
• Bluetooth 3.0 + HS (2009.4): High Speed (HS) mode; Alternative MAC/PHY implementation, high data rate by using 802.11 protocols, facing challenge from Wi-Fi, v3.0
• Bluetooth 4.0 (2010.6-2014.12): Low Energy (LE), facing IoT applications, changed the protocol, new technology; v4.0, v4.1, v4.2.

Bluetooth: Protocol Stack

• Overview: Bluetooth protocol stack.
• Radio: Bluetooth radio components for signal transmission.
• Baseband: Processes the data format for transmission.
• LMP (Link Manager Protocol): Manages the connection.
• HCI (Host Controller Interface): Interface between the host and controller.
• L2CAP (Logical Link Control and Adaptation Protocol): Handles data transmission between devices.
• SDP (Service Discovery Protocol): Locates devices and services.
• Optional Protocols: Additional protocols for supporting applications (eg. A2DP).

Bluetooth: Radio Band

• Industrial, Scientific, and Medical (ISM) band.
• 2.4GHz band (2400MHz – 2483.5MHz).
• Worldwide.
• License-free.
• Power-constrained.
• Coexistence: WLAN (802.11), Zigbee (802.15.4), etc.
• Frequency Hopping.

Bluetooth: FH Technology

• Frequency Hopping: A signal spreading technology using quickly changing radio frequencies.
• Hedy Lamarr (1914–2000): A movie star and inventor who co-created frequency hopping.
• Secret Communication System: The patent for a frequency-hopping system.

Bluetooth: FH and Time Slot

• Fast frequency hopping (1600 times/sec = 625us/slot).
• AFH (Adaptive Frequency Hopping)
• Frequency Selection Kernel (complicated algorithm, sometimes treated as a black box)
• FH sequence based on Bluetooth CLK and Bluetooth address of the Master device.
• Single-slot Packet & Multi-slot Packets.

Bluetooth: Packets

• Packet Types: ID, FHS, DATA, Control.
• BR Packet: Access Code, Sync/Address Header, Packet Type/Flow Control.
• Data, Guard, EDR Packet, Sync, EDR Payload

Bluetooth: Connection

• Inquiry/Inquiry Scan
• Page/Page scan
• Synchronization Train
• Synchronization Response
• Connection

Bluetooth: Logical Transmission

• Data Packet Types/Logical Data Links.
• Error vs delay (e.g., CS vs PS, TCP vs UDP).
• SCO (Synchronous Connection-Oriented)/ESCO (Extended SCO)
• ACL (Asynchronous Connection-Oriented Logical)

Bluetooth: Profiles

• Regulations on application layer.
• "Optional": CTP (Cordless Telephony Profile), BPP (Basic Printing Profile), SPP (Serial Port Profile), FTP (File Transfer Profile), PAN (Personal Area Network), SAP (SIM Access Profile), AV (Audio Video), HS (Handset Profile).

Bluetooth: Summary

• Classic Bluetooth Summary
  • Replacing the cable
  • Emphasis on speed and reliability
  • Transmission based on a connected link
• Advantages and Disadvantages (with EDR)
  • High speed (especially with EDR).
  • Suitable for data-intensive applications like music/file/voice.
  • Relatively high power consumption.
  • Maintains the link by performing high duty-cycle transmission.

Bluetooth vs. BLE

• IoT needs (e.g., sport bracelets):
  • Small data packets.
  • Burst transmission
  • Power sensitive.
• Similarities: Frequency band, modulation.
• Differences: Simplification (smaller duty cycle, shorter connecting time, simpler packets, connectionless advertising)

BLE Protocols

• BLE Basic Logic
  • Peripheral devices/Sensors with data
  • Central devices/smartphones want data.
• Data Passing: Advertising (Passive Scan)/Active Scan/Connection
• Data Organization: Profile/service/characteristic, Attribute/UUID

BLE - Band and Channels

• Frequency division: 40 band, 2 MHz each. 3 Advertising Channels, 37 data channels.
• Frequency Hopping: Regular hopping sequence, adaptive system to detect "used” band to avoid interference.

BLE – Advertising

• Advertising is the starting point.
• Configurable channel/power/time interval for broadcast or connection.
• ADV_IND, ADV_DIRECT_IND, ADV_NON_IND, ADV_SCAN_IND (responses from advertising)

BLE – Scan and Connect

• Passive/Active Scan (SCAN_REQ, SCAN_RSP; wanting information).
• Connection (CONNECT_REQ, NO RESPONSE NEEDED, quick connection).

BLE - Connection

• Transmit application data reliably and robustly.
• Connection Events/Interval (ranging from 7.5ms to 4s)
• Slave Latency (0 to 499).
• Connection supervision timeout (ranges from 100ms to 32s)

BLE - Packets

• Preamble, Access Address (fixed '8E89BED6' for advertising), PDU (Packet Data Unit): following GAP standards.
• AD structure (Length, type, data).
• CRC (checks integrity)

BLE Technologies

• Example: Weight Scale, advertising data.
• (includes heart rate monitor data structure).

BLE - Security

• White List (advertiser responds to known devices).
• Link Layer Privacy (address protection).
• LE Encryption (AES-128 encryption, protects content)

BLE – Data Exchange

• Key concepts in BLE:
  • Profile: Collection of services.
  • Service: Collection of characteristics.
  • Characteristic: Unique ID (UUID), value, format.
  • Data exchange: Read/write characteristic values. Authentication (may be needed).

BLE Technologies (Example: Heart Rate Monitor)

• Heart Rate Profile, Device Information Service, Heart Rate Service, Heart Rate Measurement, Body Sensor Location, Heart Rate Control Point.

Review: Why Bluetooth?

• BLE vs similar technologies (comparison table with Wi-Fi, Z-Wave, Zigbee, Thread).

What's New?

• Bluetooth 5.0 (Released Dec. 6, 2016): "Shanghai"; longer range, relaxed Tx power constraints, Channel coding applied, 2 Mbps PHY introduced, greater LE Advertising Extensions (Logic Advertising Channel, Data Length)
• Bluetooth Mesh (Released July 2017): mesh for IoT Application; each node has a role, wireless sensor network; self-organizing network.

Bluetooth: Where?

• Application scenarios (audio transmission, Bluetooth headphones, multimedia).
• Industrial uses. Smart home features (A/C remote, doorbells, locks, lighting, security, valves, windows, appliances— power sockets).
• Wearable devices (braслеts, watches, shoes, pen etc).
• BLE broadcast (advertising, indoor location, iBeacon).
• Other short range real-time communications (barrier gates, in-vehicle networks).

Test and Authentication

• Bluetooth Qualification Tests: protect IP and brand (TPG, TCRL, TS, BQE).
• RF/PHY Test, Protocol Conformance Test, Profile Test
• Profile interoperability Test.

Protocol Tests

• Classic Bluetooth Mandatory Tests (BB, LM, L2CAP, SDP, GAP).
• BLE Mandatory Tests(LL, GATT, ATT, SM, L2CAP, GAP).

RF Tests

• Verification of Radio Performances (transmitter test, output power, in-band emission, modulation characteristics, receiver test, receiving sensitivity, interference tolerance, carrier/intermodulation, blocking performance, maximum receiving power, integrity report).

• Signaling tests vs non-signaling tests (classic Bluetooth vs BLE, additional signaling complexity and test procedures)

RF Test Equipment

• List of necessary equipment (Bluetooth tester, Spectrum analyzer, RF signal generator, PC Controller, RF switch box, Vector signal analyzer.)

About CTTL - SYS

• China Telecommunication Technology Labs, founded in 1981. (Authoritative test org, Supports standards and regulation)
• Main tasks (Information/Communication tech research, Development of ICT product standards, Product inspection, verifications, assessment, and testing)

About CTTL Test Solution

• Test System Validation Decision (including Bluetooth Specs validation and compliance).

Profile Tests

• Testing application layer, checking correspondence with SIG's core profile regulations.
• Typical Profiles (A2DP, AVRCP, CTP, FTP, HFP, HID, HSP, LAP, PAN, SPP, SDAP.)
• Test devices (PTS—Profile Tuning Suite, Bluetooth Developer Studio, Radio module—SIG provided).