Applied Wireless Electronics Grzegorz Budzyń Lecture Introduction to antenna terminology Wireless data transfer Bluetooth

Transcription

1 Applied Wireless Electronics Grzegorz Budzyń Lecture 4: Introduction to antenna terminology Wireless data transfer Bluetooth

2 Plan Bluetooth Bluetooth protocol stack Application examples NFC

3 Introduction

4 Bluetooth History Began as a private development effort at Ericsson in companies joined to form thebluetooth Special Interest Group (SIG) in1998 First specification released in July 1999 Current specification is version 4.0

5 Bluetooth Goals Open Specification Voice and Data Capability Worldwide Usability Short-Range Wireless Solutions

6 Bluetooth Applications Cable Replacement PCs & peripherals, home networking, headsets Ad-hoc Networking Business card exchange, multi-player games, vending machines, white goods, etc. Data and Voice Access Points , web access, cordless telephone, etc. Industrial Inventory management systems

7 Bluetooth its place

8 Bluetooth Main features Destinied for operation in 2.4GHz range Maximumdata rate 732 kb/s (for 1.1 version) Medium access method: TDMA, controlled by host Modulation: GFSK (upto 1Mb/s), 4PSK (upto 2Mb/s) or 8DPSK(upto 3Mb/s) 1 MHz channel spacing, with frequency hopping Adaptive Frequency Hopping, for co-existence with Wi-Fi, etc

9 Bluetooth Main features Onlya fewdevicespossibleinthenetwork Devicesmake a piconetandone hostandup to 7 slavedevices Bluetoothspecificationincludesprotocols andprofiles Therearedefined3 outputpowerclassesfor 1, 10 and100 meterranges

10 Bluetooth Main features Bluetooth is packet-based protocol Bluetooth is master-slave type protocol One master may communicate upto 7 devices (piconet) Packet exchange is based on the basic clock, defined by the master, which ticks at µs intervals In the simple case of single-slot packets the master transmits in even slots and receives in odd slots

11 Bluetooth Main features Packets may be 1, 3 or 5 slots long but in all cases the master transmit will begin in even slots and the slave transmits in odd slots

12 Bluetooth versions

13 Bluetooth versions Bluetooth1.0: Versions with many interoperability problems Bluetooth1.1: Ratified as a standard: IEEE Added Received Signal Strength Indicator (RSSI) Bluetooth1.2: Faster Connection and Discovery Adaptive frequency-hopping spread spectrum (AFH) Higher transmission speeds in practice, up to 721 kbit/sthan in v1.1.

14 Bluetooth versions Extended Synchronous Connections (esco), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better support for concurrent data transfer. Host Controller Interface (HCI) support for three-wire UART Ratified as IEEE Standard Introduced Flow Control and Retransmission Modes for L2CAP

15 Bluetooth versions Bluetooth2.0+EDR: introduction of an Enhanced Data Rate (EDR) for faster data transfer The nominal rate of EDR is about 3 Mbit/s, the practical data transfer rate is 2.1 Mbit/s Bluetooth3.0+HS: Adoptedin2009 supports theoretical data transfer speeds of up to 24 Mbit/s(BT onlyestablishesconnection, transmission goes over WiFi)

16 Bluetooth versions Themainnewfeature is AMP (Alternate MAC/PHY), the addition of as a high speed transport(+hs) UnicastConnectionless Data-Permits service data to be sent without establishing an explicit L2CAP channel. It is intended for use by applications that require low latency between user action and reconnection/transmission of data. This is only appropriate for small amounts of data

17 Bluetooth versions Bluetooth4.0: Includes protocols: Classic Bluetooth based on earlier BT versions Bluetooth high speed basedon WiFi Bluetooth low energy ZigBee competitor

18 Bluetooth energy consumption Bluetooth is connection oriented. When a deviceis connected, a link is maintained, even if there is no data flowing Sniff modes allow devices to sleep, reducing power consumption to give months of battery life Peak transmit current is typically around 25mA For lowestpowerconsumptionthereisble (Bluetooth Low Energy) subset of BT4.0

19 Bluetooth Data rates

20 Bluetooth Profiles GenericAccess Profile ServiceDiscovery ApplicationProfile Serial Port Profile VirtualCOM port Dial-up Networking Profile FAX Profile LAN Access Profile Headset Profile

21 Bluetooth Profiles GenericObjectExchange Profile Object Push Profile File Transfer Profile Synchronization Profile TCS Cordless Telephony Profile Intercom Profile

22 Important Bluetooth strengths Interoperability Between manufacturers Between types of devices Ease of Use No user s guide Self-descriptive interface Low Price Same or less than the cable it is replacing Low Power Consumption No/little additional charging

23 Bluetooth Power Classes

24 Bluetooth Power Classes Bluetoothdevicesoperateinthreepower classes: ClassI, upto100mw (20dBm) and100m range ClassII, upto2.5mw (4dBm) and10m range ClassIII, upto1mw (0dBm) and1m range

25 Bluetooth Protocol Stack

26 Bluetooth Protocol Stack Source: [1]

27 Transport Protocol Group Applications IP Transport Protocol Group SDP RFCOMM Data Control L2CAP Audio Link Manager Source: [2] Baseband RF

28 Transport Protocol Group Transport ProtocolGroupiscomposedof protocols to allow Bluetooth devices: to locate each other to create, configure manage both physical and logical links that allow higher layer protocols and applications to pass data through these transport protocols

29 Transport Protocol Group Radio Frequency (RF) Sending and receiving modulated bit streams Baseband Defines the timing, framing Flow control on the link. Link Manager Managing the connection states. Enforcing Fairness among slaves. Power Management

30 Transport Protocol Group Logical Link Control &Adaptation Protocol Handles multiplexing of higher level protocols Segmentation & reassembly of large packets Device discovery & QoS In Basicmode, L2CAP provides packets with a payload configurable up to 64 kb, with 672 bytes as the default MTU, and 48 bytes as the minimum mandatory supported MTU

31 Transport Protocol Group Logical Link Control &Adaptation Protocol In Retransmission and Flow Controlmodes, L2CAP can be configured either for isochronous data or reliable data per channel by performing retransmissions and CRC checks Enhanced Retransmission Mode(ERTM)is an improved version of the original retransmission mode(reliable) Streaming Mode(SM)is a very simple mode, with no retransmission or flow control (unreliable)

32 Middleware Protocol Group Applications IP Middleware Protocol Group SDP RFCOMM Data Control L2CAP Audio Link Manager Source: [2] Baseband RF

33 Middleware Protocol Group MiddlewareProtocolGroupisadditional transport protocols to allow existing and new applications to operate over Bluetooth. Packet based telephony control signaling protocol also present. Also includes Service Discovery Protocol

34 Middleware Protocol Group ServiceDiscovery Protocol(SDP) Allowsa device to discover services offered by other devices, and their associated parameters Each service is identified by a UUID (Universally UniqueID) with official services (Bluetooth profiles) assigned a short form UUID (16b instead of 128) TCP/IP NetworkProtocolsfor packetdata communication, routing

35 Middleware Protocol Group RFCOMM Cablereplacementprotocol, Emulation of serial ports(rs-232) over wireless network Providesa simple reliable data stream to the user, similar to TCP Many Bluetooth applications use RFCOMM because of its widespread support and publicly available API on most operating systems

36 Application Group Application Group Applications IP ConsistsofBluetooth awareorunaware devices SDP RFCOMM Data L2CAP Audio Link Manager Baseband RF Control Source: [2]

37 Bluetooth Network Details

38 Bluetooth Network Types Point to Point Link Master - slave relationship Bluetooth devices can function as masters or slaves Piconet It is the network formed by a Master and one or more slaves (max 7). Each piconetis defined by a different hopping channel to which users synchronize to. Each piconethas max capacity (1 Mbps). Hopping pattern is determined by the master.

39 Piconet Structure Master Active Slave Parked Slave Standby Source: [2]

40 Packet Structure 72 bits 54 bits bits Access Code Header Payload Source: [2] Voice header Data CRC No CRC No retries FEC (optional) ARQ FEC (optional)

41 Setting up connection

42 Connection states During the connection state, the bluetooth units can be in several modes of operation: Active mode Sniff mode Hold mode Park mode

43 Connection State Machine Inquiry Page Source: [2] Standby Connected Transmit data Park Hold Sniff

44 Connection states Active mode In the active mode, the Bluetooth unit actively participates on the channel. Sniff mode In the sniff mode, the duty cycle of the slave s listen activity can be reduced. With the sniff mode, the time slots where the master can start transmission to a specific slave is reduced; that is, the master can only start transmission in specified time slots.

45 Connection states Hold mode (1/2) The hold mode is typically entered when there is no need tosend data for a relatively long time. Thus, the unit in hold mode enter a lowpower sleep mode. In Addition, with the hold mode, capacity can be made free to do other things like scanning, paging, inquiring, or attending another piconet

46 Connection states Hold mode (2/2) During the hold mode, the slave unit keeps its active member address (AM_ADDR). Prior to entering the hold mode, master and slave agree on the time duration the slave remains in the hold mode.

47 Connection states Parkmode (1/3) When a slave does not need to participate on the piconetchannel, it can enter the park mode which is a low-power mode with very little activity in the slave. In the park mode, the slave gives up its active member address AM_ADDR. Instead, it receives two new addresses to be used in the park mode: PM_ADDR: 8-bit Parked Member Address AR_ADDR: 8-bit Access Request Address

48 Connection states Parkmode (2/3) The PM_ADDR distinguishes a parked slave from the other parked slaves. This address is used in the master-initiated unpark procedure. The AR_ADDR is used by the slave in the slaveinitiated unpark procedure. All messages sent to the parked slaves have to be carried by broadcast packets because of the missing AM_ADDR.

49 Connection states Parkmode (3/3) To support parked slaves, the master established a beacon channel when one or more slaves are parked. The beacon channel serves four purposes: 1. transmission of master-to-slave packets which the parked slaves can use for re-synchronization; 2. carrying messages to the parked slaves to change the beacon parameters; 3. carrying general broadcast messages to the parked slaves; 4. unparking of one or more parked slaves.

50 Setting up connection Any Bluetooth device in discoverable modewill transmit the following information on demand: Device name Device class List of services Technical information (for example: device features, manufacturer, Bluetooth specification used, clock offset)

51 Setting up connection Any device may perform an inquiry to find other devices to connect to, and any device can be configured to respond to such inquiries Use of a device's services may require pairing or acceptance by its owner, but the connection itself can be initiated by any device and held until it goes out of range Some devices can be connected to only one device at a time, and connecting to them prevents them from connecting to other devices and appearing in inquiries until they disconnect from the other device

52 Setting up connection Every device has a unique 48-bit address Theseaddresses are generally not shown in inquiries. Instead, friendly Bluetooth names (set by user) are used This name appears when another user scans for devices and in lists of paired devices

53 Frequency Hopping Source: [1]

54 Frequency Hopping Bluetooth channel is represented by a pseudo random hopping sequence through the entire 79 RF frequencies Nominal hop rate of 1600 hops per second Channel Spacing is 1 MHz

55 Time Division Duplex Bluetooth devices use a Time-Division Duplex (TDD) scheme Channel is divided into consecutive slots (each 625 µs) One packet can be transmitted per slot Subsequent slots are alternatively used for transmitting and receiving Strict alternation of slots betweenthe master and the slaves Master can send packets to a slave only in EVEN slots Slave can send packets to the master only in the ODD slots

56 Bluetooth vs ZigBee

57 ZigBee vs standard Bluetooth

58 ZigBee vs BLE ZigBeeis older. It has gone through some iterations ZigBeehas marketsharebut a Market barrier: ZigBeeis not in PCs or mobile phones yet. Zigbeeis low power; Bluetooth LE is even lower. ZigBeestack is light; the Bluetooth LE/GATT stack is even simpler. ZigBeehas a lead on developing applications and presence

59 Example Applications

60 Bluetooth Module BTM-112

61 Bluetooth Module BTM-112

62 Bluetooth Module BTM-112 Source: [3]

63 BLE SoC CC2541

64 BLE SoC CC2541

65 Main features: CC features 2.4 GHzBLE andproprietarysocbasedon 8051 core Supportsupto 2Mbps Programmable output power up to 0dBm Excellent Receiver Sensitivity ( 94 dbm at 1MHz) 6-mm 6-mm QFN-40 Package Lowpower: Active-Mode RX Down to: 17.9 ma Active-Mode TX (0 dbm): 18.2 ma

66 NFC - Introduction

67 What is NFC? NFCmeansNearField Communicationbasing on RFID NFC isshort-rangewirelesstechnology that: uses radio-frequency waves to transfer data between a reader and a transmitter Is fast and does not require physical sight or contact between reader/scanner and the tagged item Usaberangeisa fewcentimeters

68 Features of NFC Usedin1-to-1 communication, but multipointcommunicationpossible Maximum transfer bit rate of 800kbps(in standardsupto424kbps) Operation at a frequency of 13.5 MHz No ethical concerns due to range(onlya fewcm)

69 NFC target markets Mobile Business NFC in the mobile phones Consumer Electronics NFC in all DVDs, TVs, cameras Computing NFC in all laptops, printers Entertainment, logistics and retail

70 NFC basic use cases Smart Ticketing Movie theaters or theme parks Peer-to-Peer Communication Transfer digitalfilesfrom one personal device to another Contact-less mobile Payment Use the mobile phone as a contact-less credit card or POS

71 What is RFID?

72 NFC operation modes NFC devicesoperateintwomodes: Passive communication mode: The initiator device provides a carrier fields and the target device answers by modulating the existing field. In this mode, the target device may draw its operating power from the initiator-provided electromagnetic field, thus making the target device a transponder

73 NFC operation modes NFC devicesoperateintwomodes: Active communication mode: Both initiator and target device communicate by alternately generating their own fields. A device deactivates its RF field while it is waiting for data. In this mode, both devices typically have power supplies

74 NFC operation modes In both operation modes there are possible three data transfer speeds: 106kb/s, 212kb/s and424 kb/s ASK withmanchester ormiller codingisused NFC devices are able to receive and transmit data at the same time. Thus, they can check for potential collisions if the received signal frequency does not match with the transmitted signal s frequency

75 NFC vs Bluetooth

76 NFC vs Bluetooth

77 NFC Communication

78 NFC Communication AnNFC device can be either in target mode or initiator mode Passive devices are always in target mode Thedeviceshallper defaultbe intargetmode unless the application tells it to switch into initiator mode When a device is in target mode it shall wait silently for an externally generatedrf field from the initiator to activate

79 NFC Communication A device in initiator mode shall perform initial collision avoidance to detect external RF fields beforeactivatingitsrf field. The application decides whether active or passive communicationshouldbe applied. If passive, it must perform single device detection before starting the data transfer

80 NFC Communication Thebasicframeformat Data frames have to be transmitted in pairs A request is transmitted by the initiatorand responded to by the target

81 Target states: POWER OFF SENSE RESOLUTION SELECTED SLEEP RESOLUTION* SELECTED* NFC Communication

82 NFC Communication Short frame used for command coding(106kb/s) Standard frame used for data exchange(106kb/s) Basic frame for 212, 424 kbps passive communication mode

83 NFC Communication 100% ASK modulation for communication from reader to transponder

84 NFC Communication Load modulation for communication from transponder to reader

85 NFC Example part I - professional

86 TRF7970A NFC/RFID Transceiver IC

87 TRF7970A NFC/RFID Transceiver IC Features: reader/writer IC for contactlesscommunicationat MHz Integrated Encoders, Decoders, and DataFraming for NFC Initiator, Active and Passive Target Operation for All Three Bit Rates(106 kbps, 212 kbps, 424 kbps) RF Field Detector for NFC Physical Collision Avoidance Programmable Output Power: +20 dbm(100 mw), +23 dbm (200 mw) Programmable Modulation Depth Parallel or SPI Interface (With 128-Byte FIFO)

88 TRF7970A NFC/RFID Transceiver IC

89 NFC Example part II - amateur

90 Amateur version of NFC Modulation/demodulation scheme: FSK Hardware Transmitter PC interface (MAX232A) Voltage-Controlled Oscillator (POS+25) Power Amplifier (LM6181) Loop Antenna

91 Amateur version of NFC Modulation/demodulation scheme: FSK Hardware Receiver Loop Antenna Amplifier (LM6181) Phase Lock Loop (NE564) PC interface (MAX232A)

92 Amateur version of NFC System overview

93 Schematic (transmitter) Amateur version of NFC

94 Schematic (receiver) Amateur version of NFC

95 Thank you for your attention

96 References [1] Stonestreet One, An Introduction to Bluetooth [2] FarinazEdalat, GaneshGopal, SaswatMisra, DeeptiRao, Bluetooth technology [3] BTM-112 documentation, [4] [5] [6] mid=swrs110a&genericpartnumber=cc2541&isfunctional=y& isfunctional=y

97 References [1] [2] [3] pdf [4] ntation_%20for_ieee.pdf [5] [6] pdf