WPAN/WBANs: Bluetooth and BLE
Dmitri A. Moltchanov
E-mail: [email protected]
http://www.cs.tut.fi/kurssit/ELT-53306/
ELT-53306 D.Moltchanov, TUT
• What is WPAN/WBAN:s
– expected place of WBAN/WPAN;
– usage scenarios.
• IEEE 802.15 working group;
• BAN/PAN technical challenges and design issues;
• Bluetooth:
– History;
– Specifications;
– Transport/middleware/profiles.
• Bluetooth low energy.
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1. PAN/BAN
NGN BACKBONE
3G MOBILE SYSTEMS
AD HOC NETWORKS
WLAN
BAN/PAN
WMAN
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BA
N
PA
N
LA
N
MA
N
WA
N
1m
10m
500m
3-25km
>10km
Figure 1: Coverage areas for different networks.
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SD
'Connectivity' scenario Internet scenario
PAN/BANPAN/BAN
MAN/WAN
Figure 2: Usage scenarios of BAN/PAN.
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2. IEEE 802.15802.15: specifies WPANs:
• TG 1: 802.15.1: WPAN/Bluetooth
– defines PHY and MAC of Bluetooth;
– standard issued in 2002 and 2005;
– copy/pasting with minor improvements.
• TG 2: 802.15.2: coexistence
– coexistence of WPANs with other networks in unlicensed band;
– IEEE 802.15.2-2003 published in 2003 and then ”hibernated”.
• TG 3: high rate WPAN
– 802.15.3-2003 is a MAC and PHY standard for high-rate (11 to 55 Mbit/s) WPANs;
– 802.15.3a: UWB PHY... no agreement when choosing PHY (MB-OFDM vs. DS-UWB);
– 802.15.3b-2005: improve implementation and interoperability of the MAC;
– 802.15.3b-2009: mm-wave-based PHY, 57-64Ghz unlicensed band, ¿2Gbps.
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• TG 4: Low Rate WPANs
– long battery life, low data rate, low complexity;
– 802.15.4 standard released in May 2003;
– many networks runs on top of 802.15.4: ZigBee, 6LoWPAN, WirelessHART, etc.
• Enhancements of 802.15.4
– 802.15.4a-2007: additional PHYs, e.g. UWB pulsed radio;
– 802.15.4-2006: clarification of the original standard;
– IEEE 802.15.4c: adaptation to unlicensed bands in China;
– IEEE 802.15.4d: adaptation to unlicensed bands in China;
– IEEE 802.15.4e: enhancements for industrial apps, e.g. channel hopping;
– IEEE 802.15.4f: active RFID systems;
– IEEE 802.15.4g: smart utility networks: large networks with a lot of end systems.
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• TG 5: Mesh networking
– two parts: low rate and high rate mesh networks;
– low rate: IEEE 802.15.4-2006 MAC; high rate: IEEE 802.15.3/3b MAC;
– common features: network initialization, addressing, multihop unicasting;
– low rate: multicasting, broadcasting, portability, trace route and energy saving.
• TG 6: Body Area Networks
– low-power short range standard, draft in 2011.
• TG 7: visible light communication
– draft in 2011, work in progress.
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3. BAN/PAN technical challenges and design issues
3.1. Technical challenges
PROBLEMS MAKING DESIGN OF BAN/PAN SO COMPLICATED:
• Address is not a physical location:
The station is not always stationary. The address does not give an information about location.
• Dynamically changed topology:
The network connectivity is partial at times.
• Medium boundaries are soft:
The communication range cannot be determined precisely.
• Erroneous medium:
BER in wireless network is about 10E − 4 compared to 10E − 9 in fixed networks.
• Hidden terminal problem:
Some nodes should (not) be allowed to communicate at a certain time.
TASK: BUILD A RELIABLE NETWORK USING UNRELIABLE CHANNELS.
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3.2. Design issues
WHAT CRITERIA HAVE TO BE MEET DESIGNING A BAN/PAN:
• Operational simplicity: BAN/PAN
Mobile use MUST be able to quickly set up and access network services in a SIMPLE manner.
• Power efficient operation: BAN/PAN
The main resource of MT is the power: power saving features.
• Licence-free operation: PAN
Lost cost installation is required for widespread usage, e.g., ISM band.
• Tolerance to interference: BAN/PAN
There are a lot of technologies operating in ISM band causing interference between them.
• Security: PAN
PAN is vulnerable to different attacks.
• Compatibility: BAN/PAN
Compatibility with other technologies and applications is required for a commercial success.
WHAT IS MORE: global usability (PAN/BAN), safety (BAN), quality of service.
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4. Bluetooth general descriptionWHAT WERE THE REASONS BEHIND BLUETOOTH:
• the need for personal services to communicate directly without infrastructure;
• body/personal area networking (PAN/BAN) paradigms have appeared;
• Bluetooth is the most successful standard for BAN/PAN.
THE HISTORY OF BLUETOOTH IS AS FOLLOWS:
• 1994: Ericsson’s Bluetooth project:
– the main aim was to develop a low-cost low-power radio interfaces.
• 1998: Joining to create SIG group:
– Nokia, Motorola, IBM, etc joined Ericsson to form the Bluetooth Special Interests Group;
– aim: to develop a de-facto standard for PANs.
• 2002: Approval by IEEE:
– IEEE approved the Bluetooth standard for wireless PAN: IEEE 802.15.1;
– covers only MAC and the physical layer issues, SIG covers the whole Bluetooth stack.
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4.1. Bluetooth specifications
BASIC STRUCTURE OF BLUETOOTH SPECIFICATIONS:
• core specifications: DL and PHY protocols;
• profiles: applications.
FUNCTIONS PERFORMED BY THE STACK:
• locating/connecting devices, exchanging data.
FUNCTIONS ARE LOGICALLY DIVIDED INTO THREE GROUPS:
• transport protocol group:
– RF: radio and antenna;
– baseband sublayer;
– ling manager, logical link control and adaptation sublayers;
– host controller interface.
• middleware protocol group: RFCOMM, SDP, TCS.
• application group: profiles.
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Baseband
RF: Radio and Antenna
Link manager
TCS
Applications
AUDIOLLC and AP (L2CAP)
RFCOMM SDP
Host
controller
interface
Figure 3: Protocol stack of Bluetooth (mapping to OSI X.400 is not strict!).
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5. Network topologiesTRANSPORT PROTOCOL GROUP (TPG):
• locating services: allows devices to locate each other;
• creating, configuring, and managing wireless links.
THE FOLLOWING WERE AIMS OF TPG:
• low power consumption;
• simplicity of operation;
• low cost of the communicating entity.
TO SATISFY IT, THREE GENERAL CHOICES WERE MADE:
• master-slave architecture (simplicity);
• frequency hopping communication (tolerance to interference).
• gateway-based large networking (extensions).
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5.1. Piconet
BASICS OF PICONETS:
• consists of the master and slaves, initiator of the formation: master;
• can have up to seven active(!!!) slaves at any time;
• each active slave of the piconet is a unique active member address AD ADDR.
slave 1
masterslave 2
slave 3
slave 4
slave 5
Figure 4: Illustration of the piconet.
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5.2. Scatternets
1. NOTE: PICONETS MAY OPERATE SPATIALLY:
• piconets may overlap spatially:
– piconets can operate in the same area in the same time;
– each piconet is characterized by a unique master;
– piconets hop independently with its own hopping sequences.
• with more piconets added, probability of collision increases (frequency hopping).
2. NOTE: ONLY A FEW ACTIVE DEVICES IN PICONET:
• Bluetooth unit may operate as a slave in different piconets;
• Bluetooth unit may operate as a master in only one piconet!
DEFINITION: A group of piconets between which connections exist is called a scatternet.
WHAT IS IMPORTANT:
• SIG did not develop routing protocol for scatternets!!!
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slave
masterslave
slave
slave
slave
masterslave
slave
slave
slave
masterslave
slave
slave
slave
Figure 5: Illustration of the scatternet.
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t, slots
f, frequencies
Figure 6: Frequency hopping communication (79 channels, 1Mhz each).
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6. Transport protocol groupTHIS PART OF SPECIFICATIONS DEALS WITH:
• physical layer;
• data-link layer.
BLUETOOTH RADIO:
• it operates in ISM frequency band;
• a variance of frequency modulation: GFSK;
• support 64Kbps voice channel;
• support asynchronous data channel with peak rate of 1Mbps;
• FHSS operating over the set of m = 79 channels each of width of 1MHz;
• hops are made across all channels starting at 2.402GHz and stopping at 2.480GHz;
• the transmit power of 1mW, extension to 100mW;
• the nominal link range is up to 10m (1mW), can be extended to 100m (100mW).
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6.1. Baseband sublayer
THE FOLLOWING ARE FUNCTIONS OF THE BASEBAND LAYER:
• hop selection;
• connection setup;
• medium access control.
CREATING AND MAINTAINING PICONETS:
• the address of a device:
– every device is assigned unique 48 bit address:
– the address field is partitioned into three parts:
∗ lower address part (LAP): used in piconet ID, error, security checking;
∗ remaining two parts: addresses assigned by manufacturer.
• the clock associated with a device:
– every device has 28 bit clock, called the native clock;
– 3200 times per second (interval is 312.5 µs);
– 3200 is a twice the hopping rate which is the 1600 hops per second.
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6.2. Organization of the communication channel
BASICS OF THE CHANNEL ORGANIZATION:
• the channel is divided into time slots of 625 µs.
• TDD scheme is used where master and slave alternatively transmits;
• packet transmission is aligned with the beginning of the slot;
• slots are numbered according to the clock of the master;
• master starts its transmission in even-numbered slots, slave in odd-numbered slots only;
• slave is allowed to transmit only if in the preceding slot it received a packet from the master.
master
slave
62510E-6s.
F(2k) F(2k+1) F(2k+2)
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6.3. State operations in Bluetooth
initially: standby;
master: inquiry;
joining: paging;
paging - connected;
In the connected state
a device may
participate in data
transmission.
Three power
conserving states:
park, idle, sniff.
connecting active low powerunconnected
standby
inquiry
page
connected
sniff
hold
parktransmit
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6.4. Selection of frequency hopping sequence
HOPPING SEQUENCE: FREQUENCY SELECTION MODULE (FSM):
• clock value;
• address.
CLOCK AND ADDRESS ARE DIFFERENT IN DIFFERENT MODES:
• Connected state:
– the clock value is known;
– the address of the device is known.
• Inquiry state:
– address input to the FSM is a common inquiry address;
– at the time of inquiry, no device has information about the hopping sequence.
• Paging state:
– the address of the paged device is entered in FSM.
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6.5. Inquiry state
ESSENTIAL STATE FOR BLUETOOTH:
• why: any device which is initially in the standby state enters the inquiry state;
• purpose: to collect information about other Bluetooth devices in its neighborhood.
THIS INFORMATION INCLUDES:
• address of the master;
• clock value of the master.
THE INQUIRY PROCEEDS AS FOLLOWS:
• master sends an inquiry packet on the inquiry hop sequence of frequencies:
– the common address is fed to the FSM.
• a device that wants to be discovered enters the inquiry state and listens for these packets;
• when inquiry message is received, responses with packet containing the device address.
WHY INQUIRY STATE: LOCATE A DEVICE.
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communication channelinternal i-face internal i-faceTRANS.FSM FSMTRANS.
common address
hop seq. of freq.
common address
hop seq. of freq.
ADDRESS
INQUIRY PACKET
Listening for inquiry packet
random timeout
MASTER POTENTIAL SLAVE
INQ
UIR
Y
SC
AN
RE
SP
.P
AG
ES
CA
N
PA
GE
Figure 7: Illustration of inquiry operation.
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6.6. Page state
WHY TO ENTER AND FROM WHICH STATE:
• to invite other devices to join a piconet;
• the inquiry operation precedes this state.
THIS STATE IS CLASSIFIED INTO THREE SUBSTATES:
• page sub-state (master):
– the master estimates the slave’s clock value:
∗ information obtained in the inquiry state.
– determines the hop sequence where the slave might be listening in the page scan mode;
– transmits the page message in preceding, estimated and following hop sequences.
• page scan sub-state (slave):
– slave listens the channel for a page message;
– upon receiving the page message the slave enters the slave page response sub-state;
– slave sends page response message.
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• page response sub-state (slave and master):
– the master informs the slave about its clock and address;
– the slave calculates an offset to synchronize with the master clock.
connecting activeunconnected
standby
inquiry
page
connected
sniff
hold
parktransmit
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communication channelinternal i-face internal i-faceTRANS.FSM FSMTRANS.
address + est. clock
hop seq. of freq.
PAGE RESPONSE
PAGE (3 HOP SEQ.)
Listening for PAGE packet
MASTER POTENTIAL SLAVEP
AG
E
SC
AN
RE
SP
.
CLOCK+ADDRESS
RE
SP
.
local address + clock
hop seq. of freq.
ACK
Figure 8: Illustration of page operation.
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6.7. Connected state
communication channelinternal i-face internal i-faceTRANS.FSM FSMTRANS.
local (address, clock)
hop seq. of freq.
MASTER POTENTIAL SLAVE
CLOCK+ADDRESS
PA
GE
RE
SP
.
master's (address, clock)
hop seq. of freq.
ACK
POLL (TO VERIFY)
ACKCO
NN
EC
TE
D
CO
NN
EC
TE
D
Figure 9: Illustration of connected operation.
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6.8. Packet-based communication
PACKET CONSISTS OF THE FOLLOWING COMPONENTS:
• ACCESS CODE:
– contains the address of the piconet master;
– all packets exchanged on the channel are identified by the master’s identity.
• HEADER:
This field includes many fields, among others:
– three bit active slave number: the maximum number of slaves in the piconet is 7;
– a one bit ACK/NACK field: to retransmit erroneously received frames;
– four bit packet type field: to distinguish between payload types;
– eight bit header error check: to detect errors in the header.
• PAYLOAD:
Depending on the payload size ONE, THREE, OR FIVE slots can be used for packet.
NOTE: the hop frequency used for the first slot is used for remaining slots.
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F(k) F(k+2) F(k+6)
F(k) F(k+4)
F(k+6)F(k)
F(k+4)
F(k+6)
Figure 10: Order of frequencies used when transmitting packet in multiple slots.
• ABOVE:
– single slots are used to transmits packets;
– frequencies are F(k), F(k+2), F(k+4), F(k+6) for transmission slots.
• MIDDLE:
– two slots are used to transmit a first packet;
– frequency F(k+4), not F(k+3) is used for transmitting a packet.
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LINKS IN A PICONET:
• asynchronous connectionless link (ACL):
– default link that exists once the connection is established;
– whenever a master would like to communicate, it does so;
– slave can only respond after the master’s transmission.
• synchronous connection-oriented link (SCO):
– SCO link is a symmetric between master and a slave with reserved bandwidth;
– reserved bandwidth: just reserved time slots at regular intervals;
– why: high-priority and time-bound information such as video and audio.
COMMUNICATION IN A PICONET:
• only between master and its slaves;
• is not possible between slaves;
• master does not route packets of its slaves.
HOW TO COMMUNICATE: create another piconet.
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6.9. Link management protocol
WHAT ARE MAIN FUNCTIONALITIES:
• setting and maintaining the properties of the Bluetooth link;
• power management;
• security management.
POWER MANAGEMENT
There are following of power conservation modes:
• ACTIVE MODE:
– Bluetooth unit actively participates in the piconet;
– a number of power saving algorithms are provided.
• SNIFF MODE:
– listening activity of the unit is reduced (listens only certain slots);
– master commands the source to go to the sniff mode.
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• HOLD MODE:
– slave temporarily does not support ACL packets on the channel;
– capacity is made available for paging, inquiring, or attending another piconets.
• PARK MODE:
– this is a very low-power mode allowing master to have more than 7 slaves.
– slave is given an eight bit parked member address, remains synchronized, no active address;
– a message to the parked station is sent over broadcast channel.
low
pow
er
connected
sniff hold park
releasedaddress is maintaned
norm
al
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SECURITY:
• key management: to share and distribute keys;
• authentication: to know the communicating entity;
• encryption: performed for packet payloads.
ERROR DETECTION AND CORRECTION:
• detect: checksum is added to a packet;
• correct: FEC with two rates (1/2,1/3): flexible for payload, strict (1/3) for header;
• correct: ARQ with ACKs and NACKs.
1 2 32MASTER
SLAVEError
ACK NACK
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6.10. Host controller interface
WHAT ARE FUNCTIONALITIES:
• interface layer between the layers above LMP and lower layers;
• provides access to Bluetooth hardware capabilities.
6.11. Logical link control and adaptation protocol (L2CAP)
WHAT ARE FUNCTIONALITIES:
• abstraction of higher layer protocols via multiplexing of protocols;
• segments and resembles packets to combat BER.
Baseband
RF: Radio and Antenna
Link manager
LLC and AP (L2CAP)
Host
controller
interface
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7. Middleware protocolsTO PROVIDE STANDARD INTERFACE TO APPLICATIONS:
• Service discovery protocol (SDP): fully automatic of request-response type;
• RFCOMM: virtual serial port, any application that use serial port can work seamlessly;
• IrDA interoperability protocols: support existing IrDA applications to work on Bluetooth:
– IrDA object exchange (IrOBEX) used for exchanging objects between two devices;
– Infrared Mobile Communication protocol (IrMC) used for synchronization
• Telephony control specifications (TCS):
How voice is carried:
– audio signals are carried out over SCO links at 64Kbps.
What is defined by TCS:
– call control: this allows setting up calls;
– group management: enables multiple telephone extensions;
– connectionless TCS: allows specific features.
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8. Bluetooth profilesWHY AND WHAT ARE PROFILES:
• what: provides standard to implement a specific user function;
• why: to allow interoperability between different Bluetooth implementations.
THERE ARE 13 PROFILES CLASSIFIED INTO:
• Generic profiles:
Generic Access Profile gives a way to establish secure links between master and slaves.
• Telephony profiles:
The Cordless Telephony Profile is designed for three-in-one phones.
The Headset profile specifies the wireless connection between unit and headset.
• Networking profiles:
The LAN Access gives a way to form a small LAN among themselves.
Dial-up Networking Profile, FAX Profile.
• Serial and object exchange profiles:
Serial Port Profile, Generic Object Exchange, Object Push, File Transfer, etc.
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9. Advantages and shortcomings of BluetoothADVANTAGES:
• fills the gap in networking on scales shorter than WLAN;
• exceptionally well standardized.
SHORTCOMINGS:
• Does not provide support for routing:
– communication only within a piconets, no multi-hop access to the Internet, etc.
• No support of handover:
– communication must be made within the scope of single piconet.
• Master is a bottleneck:
– the bandwidth requirements grow very fast...
• Bluetooth has operates in ISM band like IEEE 802.11b WLAN:
– coexistence solutions have to be developed...
• Complexity grows...
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10. Bluetooth low energy (BLE)Why this extension?
• Bluetooth is still alive and doing extremely well (each and every smartphone);
• Bluetooth is good for industry! Smartphone access...
• very robust to interference: frequency hopping;
• Why not to compete with ZegBee, etc.
• Bluetooth main problem: ”not so low” power consumption.
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10.1. Definition and key benefits
BLE: open, low energy, short range wireless technology.
Key benefits:
• low power consumption;
• small size (smaller than classic Bluetooth);
• connectivity to mobile phones;
• low cost, robust, efficient;
• multi-vendor interoperability;
• global availability, license free.
Note: good for small, discrete data transfers:
• temperature, time, pressure, speed: sensing;
• local advertisements: e.g. boarding gates;
• energy: 2mAh per day - 4 years from a coin cell!
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Bluetooth LE:
• is a new technology;
• designed with some constraints.
Imposed constraints
• reuse as much Bluetooth RF as possible;
• reuse as much of BluetoothL2CAP as possible
• reuse as much of BluetoothHCI as possible.
Design goals:
• Lowest possible power operation
• Lowest possible latency;
• Widest possible range of interoperable devices and applications.
Note: implicitly targeting industrial apps as well...
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10.2. Effect of constraints
Reusing RF means:
• only needs approximately 60% of RF silicon area compared to Bluetooth;
• can use the same antenna as Bluetooth(and possibly Wi-Fi);
• can time division multiplex with Bluetooth.
Reusing HCI means:
• same HCI physical interfaces - UART/USB/SDIO;
• same HCI packet formats;
• same HCI drivers in OS.
Reusing RF means:
• segregation of stacks happens ata known multiplexing point!
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Optimizing for lowest power consumption means:
• turning radio off for as much of the time as possible;
• reducing the complexity of a single mode device to almost nothing;
• designing a connectionless data model.
Complexity is important:
• reduced complexity and state means reduced memory requirements
• reduced memory requirementsmeans reduced leakage current;
• reduced leakage current radio off means battery lifetimes of years.
And it reduces the cost:
• 80% to 60% of the cost of traditional Bluetoothchips
• this is a lot given the cost of conventional Bluetooth chip.
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10.3. Achieving low power
By keeping the radio off:
• Lower standby time (i.e. lower duty cycle);
• Faster connection (i.e. able to send data quicker);
• Lower peak power (i.e. able to be used with coin cell battery).
Lower standby time?
BLE uses only 3 advertising channels:
• Classic Bluetooth: 16 to 32 channels;
• RF is on for 1.2 ms instead of 22.5 ms.
Idle current is dominated by deep sleep current:
• Sensor type of applications send data less often (0.5s to 4s intervals);
• RF current is negligible due to low duty cycles;
• Protocols optimized for this communication model.
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Faster Connections:
• BLE: a device that is advertising is able to connect to a scanning device
• The devices can connect and sendand acknowledge data in 3 ms
– Classic Bluetooth: link level connection can take up to 100ms;
– Classic Bluetooth: L2CAP connection can take significantly longer.
Lower Peak Power:
• BLE uses relaxed RF parameters
– GFSK modulation index increased (from 0.35 to 0.55);
– Allowing better range / robustness.
• Packet length restricted
– Together with GFSK gives lowest complexity transmitter/receiver;
– This results in a lower peak power.
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10.4. Data rate and throughput
BLE is not about data rate/throughput:
• concentrates on lowest possible power consumption;
• can do 260 kbps maximum data rate;
• it burns power doing this;
• Classic Bluetooth is more efficient at these data rates.
• target? sensor networks!
Bluetoothlow energy is about transferring state:
• small, infrequent bits of data;
• lowest possible power consumption;
• lowest latency;
• that is: send sensored data ASAP!
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ELT-53306 D.Moltchanov, TUT
10.5. PHY layer
Splits the 2.4 GHz ISM band into 40 channels:
• 3 Advertising Channels;
• 37 Data Channels;
• fn = 2402 + 2nMHz.
GFSK Modulation:
• Modulation index 0.5: better range than classic Bluetooth;
– allows use of fewer advertising channels;
– reduces power consumption;
– increases connection speeds;
• Can reuse existing RF parts in a Bluetoothchip;
– Minimal additional cost in dual-mode chips.
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ELT-53306 D.Moltchanov, TUT
10.6. Master/slave topology
Highly asymmetric!
Master is typically the central device:
• Smartphone, computer, tablet.
Slave is typically the peripheral device:
• Heart Rate Belt, Thermostat, etc.
Slave is very VERY power sensitive:
• Must be optimized for minimal radio on time
Master is time sensitive:
• Must be optimized for latency requirements.
Lecture: WPAN/WBANs: Bluetooth and BLE 49
ELT-53306 D.Moltchanov, TUT
10.7. Separate advertising and data channels
Data Channels:
• Used to transfer reliable data robustly;
• adaptive frequency hopping over 37 channels;
• fast acknowledgement scheme;
• if data doesnt get through, resent on next frequency.
Advertising Channels:
• 402, 2426, 2480 MHz! Why? Avoids interference with Wi-Fi traffic;
• Used by peripherals to advertise presence;
– when first powered on;
– when they have data to send - central devices connect and get data;
– just to broadcast data to anybody scanning.
Lecture: WPAN/WBANs: Bluetooth and BLE 50
ELT-53306 D.Moltchanov, TUT
10.8. Security
What? uses AES-128 with CCM encryption engine
Uses Key Distribution to share various keys:
• Identity Resolving Key is used for privacy;
• Signing Resolving Key provides fast authentication without encryption;
• Long Term Key is used for encryption.
Pairing encrypts the link using a Temporary Key:
• derived from passkey, NFC pairing, public key exchange (v1.1);
• then distribute keys.
Asymmetric key model:
• slave gives keys to master with a diversifier;
• slave can then recover keys from the diversifier.
Lecture: WPAN/WBANs: Bluetooth and BLE 51
ELT-53306 D.Moltchanov, TUT
10.9. Encryption
RFC 3610 based AES-128 encryption:
• Counter Mode Cipher Block Chaining Message Authentication Code;
• Counter mode CBC-MAC = CCM.
Each new data packet has a Message Integrity Check:
• 39 bit counter, 1 direction bit;
• 64 bit Initialization Vector 32 bits contributed by each device;
• MIC is 32 bits in length.
MIC is separate from the CRC:
• CRC can allow immediate acknowledgment;
• packet is only sent to host after MIC checked;
• lowest peak power.
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ELT-53306 D.Moltchanov, TUT
10.10. Survavibility
Robustness is Vital for Bluetooth:
• it must be robust against 2.4 GHz ISM band interference;
• Wi-Fi, 802.15.4, X-10, proprietary, etc.
Coexistence is Vital:
• should not interfere with existing Wi-Fi infrastructure/ad-hoc network;
• Adaptive Frequency Hopping is needed
• FCC recognizes this as the best way to avoid interference;
• Discovering devices / connecting devices should not break Wi-Fi;
• It must not affect Bluetoothheadsets.
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ELT-53306 D.Moltchanov, TUT
10.11. Power consumption
Relative consumption:
• sleep time is way more longer;
• power mode 1: 3us wake up time consuming 235uA;
• power mode 2: wake up via sleep timer consuming 0.9uA;
• power mode 3: via external interrupt consuming 0.4uA.
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ELT-53306 D.Moltchanov, TUT
Power consumption during the connection event:
• between connection events: power mode 2;
• turning off: voltage regulator, processor, oscillator;
• active: sleep timer, RAM and registers retained.
• going active: via I/O interrupt or expiring sleep timer.
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