wpan/wbans: bluetooth and ble - tut · 2016-04-04 · sig did not develop routing protocol for...

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.

Lecture: WPAN/WBANs: Bluetooth and BLE 2


1. PAN/BAN

NGN BACKBONE

3G MOBILE SYSTEMS

AD HOC NETWORKS

WLAN

BAN/PAN

WMAN



BA

N

PA

N

LA

N

MA

N

WA

N

1m

10m

500m

3-25km

>10km

Figure 1: Coverage areas for different networks.



SD

'Connectivity' scenario Internet scenario

PAN/BANPAN/BAN

MAN/WAN

Figure 2: Usage scenarios of BAN/PAN.



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.



• 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.



• 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.



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.



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.



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.



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.



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!).



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).



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.



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!!!



slave

masterslave

slave

slave

slave

masterslave

slave

slave

slave

masterslave

slave

slave

slave

Figure 5: Illustration of the scatternet.



t, slots

f, frequencies

Figure 6: Frequency hopping communication (79 channels, 1Mhz each).



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).



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.



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)



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



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.



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.



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.



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.



• 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




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.



6.7. Connected state


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.



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.



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.



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.



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.



• 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



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



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



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.



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.



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...



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.



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!



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...



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!



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.



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.



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.



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!



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.



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.



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.



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.



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.



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.



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.



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.



11. Technical comparison


wpan/wbans: bluetooth and ble - tut · 2016-04-04 · sig did not develop routing protocol for...

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