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Fachbereich Informatik und Elektrotechnik
Ubicomp
Ubiquitous Computing
• IEEE 802.15.4
• ZigBee
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Structure - IEEE
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Introduction, Protocol Stacks
IEEE 812.15
IEEE 812.15.4 WPAN
IEEE 802.15.4 PHY
IEEE 802.15.4 MAC
Zigbee Routing Layer
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15
WPANs Wireless Personal Area Networks:
à IEEE 802.15
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15
Working Group 802.15 and the Other
IEEE Wireless Standards Areas
IEEE 802.15 Wireless Personal Area
Network (WPAN) Working Group
IEEE 802.11
WLAN Working Group
IEEE 802.16
WMAN Working Group
Task Group 1
WPAN/Bluetooth™
Task Group 2
Coexistence
Task Group 3
WPAN High Rate
Task Group 3a
WPAN Alt.
Higher Rate
IEEE 802.18
Radio Regulatory TAG
IEEE 802.19
Coexistence TAG
IEEE 802.20
Mobile BWA Working Group
Task Group 4
WPAN Low Rate
Ubiquitous Computing,  Helmut Dispert
IEEE 1451.5
Working Group
for Wireless Sensors
Fachbereich Informatik und Elektrotechnik
802.15
Working Group 15:
Wireless Personal Area Networks
Synopsis:
802.15 focuses on the development of consensus standards for Personal
Area Networks or short distance wireless networks. These WPANs
address wireless networking of portable and mobile computing devices
such as PCs, PDAs, peripherals, cell phones and consumer electronics.
The goal is to publish standards, recommended practices, or guides that
have broad market applicability and deal effectively with the issues of
coexistence and interoperability with other wired and wireless networking
solutions.
802.15 is part of the 802 Local and Metropolitan Area Network Standards
Committee of the IEEE Computer Society. The IEEE-SA is an international
membership organization serving today's industries with a complete
portfolio of standards programs.
The latest status of 802.15 and other IEEE802 activities is available at
http://standards.ieee.org.
IEEE
Ubiquitous Computing,  Helmut Dispert
Glyn Roberts, STMicroelectronics, Inc
Fachbereich Informatik und Elektrotechnik
802.15
802.15 Org. Chart - Officers and Affiliations
802.15 WG
WG Chair-Bob Heile, Appairent
Vice Chair-Jim Allen, Appairent
Co-Vice Chair-Ian Gifford, Consultant
Secretary
Pat Kinney, Consultant
Asst. Secretary
Mike McInnis, Boeing
Publicity Committee
Task Groups
Study Groups
Glyn Roberts, Chair
STMicroelectronics
Task Group 1
Task Group 2
Task Group 3
Task Group 3a
Task Group 4
Bluetooth Radio 1
Ian Gifford, Chair
Consultant
Coexistence
Steve Shellhammer,
Chair, Symbol
High Rate
John Barr, Chair
Motorola
15.3 Alt Higher Rate Phy
Bob Heile, Chair
Appairent
Low Rate
Bob Heile, Chair
Appairent
MAC Sublayer
PHY Layer
Coexistence Model
Coexistence Mechanisms
MAC Sublayer
PHY Layer
PHY Layer
MAC Sublayer
PHY Layers
Glyn Roberts, STMicroelectronics, Inc
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15
802.15 WG is developing 3 MACs and 5 PHYs, TG3a
is the 6th PHY
Logical Link
Control Sublayer
Medium Access
Control Sublayer
Physical
Layer
Service Specific
Convergence Sublayer
(SSCS)
{
{
MAC Sublayer
802.15.1
{
2.4 GHz
WPAN-Bluetooth
Bluetooth(TM)
802.15.1
2.4 GHz
WPAN-HR
High Rate
802.15.3
?
WPAN-HR
Higher Rate
802.15.3a
868-868.6 MHz
WPAN-LR
Low Rate
802.15.4
902-928 MHz
WPAN-LR
Low Rate
802.15.4
2400-2483.5 GHz
WPAN-LR
Low Rate
802.15.4
1 Mb/s
11 Mb/s
22 Mb/s
55 Mb/s
110 Mb/s
? Mb/s
2 kb/s
20 kb/s
2 kb/s
20 kb/s
2 kb/s
250 kb/s
802.2 LLC
802.15
= Other LLC
MAC Sublayer
802.15.3
MAC Sublayer
802.15.4
= Draft in process or complete
= Draft not defined e.g., CFP, etc.
Ubiquitous Computing,  Helmut Dispert
Glyn Roberts, STMicroelectronics, Inc
Fachbereich Informatik und Elektrotechnik
802.15
Task Group 4: WPAN Low Rate
Synopsis:
The WPAN Low Rate Task Group (TG4) is chartered to investigate
a low data rate solution with multi-month to multi-year battery life
and very low complexity. This standard specifies two physical
layers: an 868 MHz/915 MHz direct sequence spread spectrum PHY
and a 2.4 GHz direct sequence spread spectrum PHY. The 2.4 GHz
PHY supports an over air data rate of 250 kb/s and the 868
MHz/915 MHz PHY supports over the air data rates of 20 kb/s and
40 kb/s. The physical layer chosen depends on local regulations
and user preference. Potential applications are sensors,
interactive toys, smart badges, remote controls, and home
automation.
More info is available at http://ieee802.org/15/pub/TG4.html.
Glyn Roberts, STMicroelectronics, Inc
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15
IEEE 802.15 WPAN™ Task Group 4 (TG4)
Monday, 7 May 2007
The IEEE 802.15 TG4 was chartered to investigate a low data rate solution with
multi-month to multi-year battery life and very low complexity. It is operating in an
unlicensed, international frequency band. Potential applications are sensors,
interactive toys, smart badges, remote controls, and home automation.
IEEE 802.15 TG4 FEATURES
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Data rates of 250 kbps, 40 kbps, and 20 kbps.
Two addressing modes; 16-bit short and 64-bit IEEE addressing.
Support for critical latency devices, such as joysticks.
CSMA-CA channel access.
Automatic network establishment by the coordinator.
Fully handshaked protocol for transfer reliability.
Power management to ensure low power consumption.
16 channels in the 2.4GHz ISM band, 10 channels in the 915MHz I and one
channel in the 868MHz band.
http://grouper.ieee.org/groups/802/15/pub/TG4.html
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15
IEEE 802.15 WPAN™ Task Group 4b (TG4b)
Monday, 7 May 2007
Overview
The IEEE 802.15 task group 4b was chartered to create a project for
specific enhancements and clarifications to the IEEE 802.15.4-2003
standard, such as resolving ambiguities, reducing unnecessary
complexity, increasing flexibility in security key usage, considerations
for newly available frequency allocations, and others.
http://grouper.ieee.org/groups/802/15/pub/TG4b.html
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4
IEEE 802.15 WPAN™ Task Group 4 (TG4)
The IEEE 802.15 TG4 was chartered to investigate a low
data rate solution with multi-month to multi-year battery
life and very low complexity. It is operating in an
unlicensed, international frequency band. Potential
applications are sensors, interactive toys, smart badges,
remote controls, and home automation.
http://www.ieee802.org/15/pub/TG4.html
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
7-Layer OSI Reference Model
77
Application
Application Layer
Layer
66
Presentation
Presentation Layer
Layer
55
Session
Session Layer
Layer
44
Transport
Transport Layer
Layer
33
Network
Network Layer
Layer
22
Data
Data Link
Link Layer
Layer
LLC & MAC Sublayers
Physical Addressing
11
Physical
Physical Layer
Layer
Media, Signalling & Transmission
OSI-Model
OSI-Model
Ubiquitous Computing,  Helmut Dispert
Radio LInk
Data Representation and Encryption
Internhost Communication
End-to-End Connections & Reliability
Path Determination & IP
Logical Addressing
Fachbereich Informatik und Elektrotechnik
Comparison
7-Layer
7-Layer
ISO/OSI
ISO/OSI Model
Model
Simplified
Simplified 5-Layer
5-Layer
ISO/OSI
Model
ISO/OSI Model
77
Application
Application Layer
Layer
User
User Application
Application
66
Presentation
Presentation Layer
Layer
55
Session
Session Layer
Layer
44
Transport
Transport Layer
Layer
33
Network
Network Layer
Layer
Network
Network Layer
Layer
22
Data
Data Link
Link Layer
Layer
Data
Data Link
Link Layer
Layer
11
Physical
Physical Layer
Layer
Physical
Physical Layer
Layer
Ubiquitous Computing,  Helmut Dispert
Application
Application Profile
Profile
IEEE
IEEE 802
802 Model
Model
Upper
Upper Levels
Levels
Logical
Logical Link
Link Control
Control (LLC)
(LLC)
Media
Access
Control
Media Access Control (MAC)
(MAC)
Physical
Physical
Fachbereich Informatik und Elektrotechnik
Comparison
ZigBee vs. Bluetooth
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 and ZigBee
802.15.4
• Focuses on specification of lower 2 layers of protocol
stack
• Details specification of PHY and MAC by offering
building blocks for “star, mesh, and cluster tree
networks”
ZigBee
• Low data rate, low power consumption, wireless
networking protocol aimed at automation and remote
control applications
ZigBee vs. Bluetooth
• Simpler, lower data rate, sleeps more often
• Leads to longer lifetimes, but less responsive
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 WPAN Standard
WPAN components
• Fully Functional Devices (FFD)
• Reduced Function Devices (RFD)
• Each network has at least one FFD as PAN coordinator
Network Topologies
• Star (home automation, PC peripherals, toys, games)
• Mesh/Peer-to-Peer (industrial control, WSNs, inventory
tracking)
• Cluster Tree (special case of Peer-to-Peer with many
FFDs)
LR-WPAN Device Architecture
• PHY/MAC
• 802.2 Logical Link Control (LLC)
• Service Specific Convergence Sublayer (SSCS)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Network Topology , Device Architecture
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Comparison: ZigBee - Bluetooth
Bluetooth
ZigBee
Sensitivity
- 82dbm(6,2pW)
- 92dbm(0,63pW)
Flexibility No. of supported
nodes
8 (in a star)
65536 (in a mesh)
Security
SAFER (64/128bit) AES (128bit)
optional guaranteed time
slot
Latency requirements
Range
10 m
up to 75 m in LOS condition
Increasing
SAFER:
LOS:
Secure And Fast Encryption Routine
Loss of signal
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Protocol Stack
Application
Application Interface
Network Layer
Data Link Layer
MAC Layer
MAC Layer
PHY Layer
Silicon
ZigBee
Stack
Application
Philips Semiconductor
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Comparison: Bluetooth Architecture
Voice
Telephony
Control
Protocol
Dial-up
Networking
vMessage
vNote
vCal
vCard
Group Call
Cordless
Headset
Intercom
User Interface
Fax
OBEX
Service
Discovery
Protocol
HOST
RFCOMM
(Serial Port)
L2CAP
Host Control Interface
Link Manager
Link Controller
MODULE
Baseband
RF
Silicon
Bluetooth
Stack
Applications
Philips Semiconductor
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
Application
ZigBee Stack
IEEE Stack
Product Developer
ZigBee Alliance
IEEE 802.15.4
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 PHY / MAC
IEEE 802.15.4
PHY / MAC
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4
33
Upper Layers
LR-WPAN
Device Architecture
802.2 LLC
22
7-Layer OSI Communication
Model Adapted to the
IEEE 802.15.4 Standard
SSCS
MAC
11
PHY
Physical
Medium
Ubiquitous Computing,  Helmut Dispert
• LR-WPAN:
Low Rate Wireless Personal Area Network
• LLC:
Logical Link Control
• SSCS:
Service Specific Convergence Sublayer
Fachbereich Informatik und Elektrotechnik
Comparison OSI-Model and ZigBee
Application
Application Layer
Layer
Applications
Applications
Presentation
Presentation Layer
Layer
Application
Application Profiles
Profiles
Session
Session Layer
Layer
Application
Application Framework
Framework
Transport
Transport Layer
Layer
Network
Network and
and Security
Security
Layer
Layer
Network
Network Layer
Layer
Data
Data Link
Link Layer
Layer
MAC Layer
Physical
Physical Layer
Layer
PHY
PHY Layer
Layer
OSI-Model
OSI-Model
2.4
2.4GHz
GHz
Application
Application
Defined by ZigBee or OEM
ZigBee
ZigBee Stack
Stack
Defined by ZigBee Alliance
Silicon
Silicon
Ubiquitous Computing,  Helmut Dispert
868/915
868/915MHz
MHz
Defined by 802.15.4
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
IEEE 802.15.4
Modulation types, frequency bands and data rates
The IEEE 802.15.4 specifies four PHYs.
a) An 868/915 MHz direct sequence spread spectrum (DSSS) PHY
employing binary phase-shift keying (BPSK) modulation
b) An 868/915 MHz DSSS PHY employing offset quadrature phase-shift
keying (O-QPSK) modulation (optional)
c) An 868/915 MHz parallel sequence spread spectrum (PSSS) PHY
employing BPSK and amplitude shift keying (ASK) modulation (optional)
d) A 2450MHz DSSS PHY employing O-QPSK modulation.
DSSS - Direct-Sequence Spread Spectrum Technology
Direct-sequence spread-spectrum (DSSS) generates a redundant bit pattern for each bit
to be transmitted. This bit pattern is called a chip (or chipping code). The longer the chip,
the greater the probability that the original data can be recovered (and, of course, the
more bandwidth required). Even if one or more bits in the chip are damaged during
transmission, statistical techniques embedded in the radio can recover the original data
without the need for retransmission.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
IEEE 802.15.4:
PHY Frequency Bands and Data Rates
Spreading Parameters
Data Parameters
PHY
[MHz]
Frequency
Band [MHz]
Chip Rate
[chip/s]
Mode
Bit
Rate
[kb/s]
Symbol
Rate
[kbaud]
Symbols
868
868 - 870
300k
BPSK
20
20
Binary
915
902 - 928
600k
BPSK
40
40
Binary
868
optional
868 - 870
400k
ASK
250
12,5
20-bit PSSS
915
optional
902 - 928
600k
ASK
250
50
5-bit PSSS
868
optional
868 - 870
400k
O-QPSK
100
25
16-ary
Orthogonal
915
optional
902 - 928
600k
O-QPSK
250
62.5
16-ary
Orthogonal
2400
2400 – 2483.5
2M
O-QPSK
250
62.5
16-ary
Orthogonal
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
IEEE 802.15.4:
PHY Frequency Bands and Data Rates
supported by ZigBee
Spreading
Parameters
Data Parameters
PHY
[MHz]
Frequency
Band [MHz]
Channel
Numbering
Chip
Rate
Mode
Bit
Rate
Symbol
Rate
Modulation
868
868 - 870
0
300k
chip/s
BPSK
20
kb/s
20
kbaud
BPSK
915
902 - 928
1 - 10
600k
chip/s
BPSK
40
kb/s
40
kbaud
BPSK
2400
2400 – 2483.5
11 - 26
2M
chip/s
O-QPSK
250
kb/s
62.5
kbaud
16-ary
Orthogonal
BPSK: Binary phase shift keying
O-QPSK: Offset quadrature PSK
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4
PHY Overview
Operating Frequency Bands
2 MHz
PHY
868MHz / 915MHz
868.3 MHz
902 MHz
Channel 0
928 MHz
Channels 1-10
No overlap
with WiFi
PHY
2.4 GHz
5 MHz
15
2.4 GHz
Ubiquitous Computing,  Helmut Dispert
20
Channels 11-26
25 26
2.4835 GHz
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4
PHY Overview
Center frequencies of channels k:
k = 0:
f c = 863,3 MHz
k = 1,...,10 :
f c = (906 + 2(k − 1)) MHz
k = 11,..., 26 :
f c = (2405 + 5( k − 11)) MHz
Important:
Duty cycle for European 868 MHz band limited to 1%.
à
effective data rate: 200bit/s.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 PHY
Signal power measurements that can be
performed by the IEEE 80.15.4 radio:
Receiver Energy Detection (ED)
–
–
Estimate of received signal power within bandwidth of
channel
Intended for use by network layer for channel selection
Link Quality Indication (LQI)
–
–
Characterization of strength / quality of received packet
Implemented using ED, SNR, or combination
Clear Channel Assessment (CCA)
–
–
–
–
Energy above ED threshold
Carrier Sense Only
Carrier Sense with energy above threshold
Required by MAC-layer to implement CSMA/CA (Carrier
Sense Multiple Access / Collision Avoidance)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
802.15.4 modulation techniques.
a) 2,4 GHz
b) 868/915 MHz
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
2.45 GHz direct sequence spread spectrum (DSSS) RF modulation
format as defined in IEEE 802.15.4.
The 2.45 GHz PHY employs a 16-ary quasi–orthogonal modulation technique.
The modulation and spreading functions:
Transmitted
bit-stream
(LSB first)
from PPDU*
Bit-toSymbol
Symbolto-Chip
O-QPSKModulator
Modulated
Signal
Each byte is divided into two symbols, 4 bits each. The least significant
symbol is transmitted first. For multi-byte fields, the least significant byte is
transmitted first, except for security related fields where the most
significant byte it transmitted first. Each symbol is mapped to one out of 16
pseudo-random (PN) sequences, 32 chips each.
The symbol to chip mapping is shown in the following table.
The chip sequence is then transmitted at 2 MChips/s, with the least
significant chip (C0) transmitted first for each symbol.
* Physical Protocol Data Unit (PPDU)
Ubiquitous Computing,  Helmut Dispert
Ref.: http://www.chipcon.com
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
Data symbol
(decimal)
Data symbol
(binary)
(b0, b1, b2, b3)
Chip values
(c0 c1 ... c30 c31)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0000
1000
0100
1100
0010
1010
0110
1110
0001
1001
0101
1101
0011
1011
0111
1111
11011001110000110101001000101110
11101101100111000011010100100010
00101110110110011100001101010010
00100010111011011001110000110101
01010010001011101101100111000011
00110101001000101110110110011100
11000011010100100010111011011001
10011100001101010010001011101101
10001100100101100000011101111011
10111000110010010110000001110111
01111011100011001001011000000111
01110111101110001100100101100000
00000111011110111000110010010110
01100000011101111011100011001001
10010110000001110111101110001100
11001001011000000111011110111000
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
The modulation format is Offset – Quadrature Phase Shift Keying
(O-QPSK) with half-sine chip shaping. This is equivalent to MSK
(minimum-shift keying) modulation. Each chip is shaped as a halfsine, transmitted alternately in the I and Q channels with one half
chip period offset.
πt

Modulator function for half-sine pulse
sin(
), 0 ≤ t ≤ 2Tc

construction in Offset Quadrature
p (t ) = 
2Tc
Phase-Shift Keying (O-QPSK):
 0,
otherwise

with Tc:
delay between the two phases
O-QPSK uses two sine-based carriers. One is in-phase (I) and the
other is in-quadrature (Q), which means it is offset by 90º (0/90
box in DSSS modulator). This means that two bits can be
transmitted at the same time. Even bits of the chip are sent on
the I-phase, odd bits on the Q-phase.
The two phases are added and sent by the antenna.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
A nibble of raw data to be sent:
0101010111010101 0000 0101001010010110110110110100101110001001001010010011001
bit to symbol
0000B = 0S
symbol to chip
bit rate for O-QPSK:
bit rate = chip rate ⋅
0S = 11011001110000110101001000101110C
4
32
O-QPSK
modulation
I / Q Phases when transmitting a zero-symbol chip sequence, TC = 0.5 µs.
To form the offset between I-phase and Q-phase chip modulation, the Q-phase chips must be delayed
by TC with respect to the I-phase. TC is the inverse of the chip rate.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation Data Rate
Calculating the data rate:
The chipping rate for the 2.4-GHz PHY is 2 million chips
per second.
32 chips are sent for every 4 bits of real data, therefore
the effective data rate is:
 4
bit rate = 2 ⋅10 ⋅   = 250 kbps
 32 
6
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 – 802.11
Frequency plan, which allows the parallel non-disturbed operation of
three IEEE802.11 and four IEEE802.15.4 channels.
Axel Sikora1, Voicu F. Groza:
Coexistence of IEEE802.15.4 with other
Systems in the 2.4 GHz-ISM-Band
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Symbols and Chip Values
Ref.: http://www.chipcon.com
Typical 802.15.4 medium realization:
DSSS modulator (Direct Sequence Spread Spectrum)
Chipcon
CC2420
The CC2420 is a low-cost transceiver designed specifically for low-power, low-voltage RF applications in
the 2.4 GHz unlicensed ISM band. It is the first commercially available RF Transceiver compliant with the
IEEE 802.15.4 standard and the first RF-IC that can be qualified for use in 2.4 GHz ZigBee products.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
868/915 MHz band binary phase-shift keying (BPSK) PHY
specification
The 868/915 MHz BPSK PHY employs direct sequence spread spectrum
(DSSS) with BPSK used for chip modulation and differential encoding for
data symbol encoding:
Transmitted
bit-stream
(LSB first)
from PPDU*
Differential
Encoder
* Physical Protocol Data Unit (PPDU)
Ubiquitous Computing,  Helmut Dispert
Bit-toChip
BPSKModulator
Modulated
Signal
Ref.: http://www.chipcon.com
Fachbereich Informatik und Elektrotechnik
802.15.4 Modulation and spreading functions
Symbol-to-chip mapping for BPSK
Input Bits
0
1
Chip values
(c0 c1 ... c13 c14)
111101011001000
000010100110111
The raised cosine pulse shape (roll-off factor 1) used to represent
each baseband chip is described by equation
 sin πt Tc cos πt Tc
⋅

p (t ) =  πt Tc 1 − 4t 2 Tc 2

1
,t ≠0
,t =0
Ref.: http://www.chipcon.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 Summary
PPDU format
Basic components of the PPDU packet:
• A synchronization header (SHR), which allows a receiving device to
synchronize and lock onto the bit stream
• A PHY header (PHR), which contains frame length information
• A variable length payload, which carries the MAC sublayer frame.
Format of the PPDU packet structure:
Octets
1
Preamble
SFD
SHR
PPDU: Physical Protocol Data Unit (PPDU)
Ubiquitous Computing,  Helmut Dispert
Frame Length
(7 bits)
variable
Reserved
(1 bit)
PHR
PSDU
PHY payload
PSDU: Physical Service Data Unit (PPDU)
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
PHY Overview - Packet Structure
PHY Packet Fields
•
•
•
•
Preamble (32 bits) – synchronization
Start of Packet Delimiter (8 bits)
PHY Header (8 bits) – PSDU length
PSDU (0 to 1016 bits) – Data field
Preamble
Start of
Packet
Delimiter
6 bytes
Ubiquitous Computing,  Helmut Dispert
PHY
Header
PHY Service
Data Unit (PSDU)
0-127 bytes
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 PHY
6 bytes
Preamble
Start of
Packet
Delimiter
4 bytes
1
Preamble
SFD
0-127 bytes
PHY
Header
PHY Service Data Unit
(PSDU)
1
Frame Length
(7 bits)
SHR
PHR
variable
Reserve
(1 bit)
PSDU
PHY payload
PHY protocol data unit
• SHR: Synchronization Header, allows receiving device to synchronize with
bit stream
• PHR: PHY header, contains frame length information
• Variable length payload carrying MAC sublayer frame
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 - Frame
The structure of the 802.15.4 frame corresponds to a large extend to the
802.11 standard.
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC
Wireless Personal Area Networks:
à IEEE 802.15
Layered Structure
IEEE 802.15.4 MAC
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
MAC Overview - Device Classes
• Full function device (FFD)
–
–
–
–
Full implementation of IEEE 802.15.4
Any topology
Network coordinator capable
Talks to any other device
• Reduced function device (RFD)
–
–
–
–
–
Implements a subset of IEEE 802.15.4
Limited to star topology
Cannot become a network coordinator
Talks only to a network coordinator
Very simple implementation
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
MAC Frame Formats
General MAC Frame format
Octets: 2
1
Frame
Control
Sequence
number
Addressing
fields
MHR
1
variable
2
Command
frame
identifier
Command
payload
FCS
MAC payload
MFR
FCS: Frame Check Sequence (checksum)
MHR: MAC Header
MFR: MAC Footer
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
MAC Frame Formats
General MAC Frame format
MAC
payload
MFR
0/5/6/10/14
variable
2
Auxiliary
Security
Header
Frame
payload
FCS
MHR
2 bytes
1
Frame
Control
Sequence
number
2
bytes
1
Frame Sequence
Control number
0 or 2
Addressing
fields
0, 2 or 8
Destination
Destination
PAN
Address
Identifier
0 or 2
0, 2 or 8
0/5/6/10/14
variable
2/4
Source
PAN
Identifier
Source
Address
Auxiliary
Security
Header
Frame
payload
FCS
Addressing Fields
0-102/118 bytes
Up to 127 bytes
Jan. 12, 2010 – Ref.: https://mentor.ieee.org/802.15
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
PHY / MAC
MAC Overview – General Frame Structure
Four Types of MAC Frames
• Data Frame
• Beacon Frame
• Acknowledgment Frame
• MAC Command Frame
2
bytes
MAC
1
0 or 2
Frame Sequence
Control number
Preamble
0, 2 or 8
Destination
Destination
PAN
Address
Identifier
SFD
PHY
Ubiquitous Computing,  Helmut Dispert
Frame
Length
(7 bits)
+ optional
Superframe Structure
0 or 2
0, 2 or 8
0/5/6/10/14
variable
2/4
Source
PAN
Identifier
Source
Address
Auxiliary
Security
Header
Frame
payload
FCS
Reserve
(1 bit)
PSDU
Fachbereich Informatik und Elektrotechnik
802.15.4 / MAC-PHY-Layer
MAC und PHY sind in jeweils zwei Bestandteile aufgeteilt. Die Behandlung
des Datenverkehrs übernimmt die eigentliche Protokolleinheit (Entity).
Zusätzlich existieren sog. Management Entities, die die Verwaltung des
Netzwerks übernehmen. Diese Aufteilung ist auch schon von anderen
Funkstandards, wie dem 802.11, verwendet worden.
MLME-SAP
MCPS-SAP
MAC Common Part Sublayer
MLME (MAC PIB)
PD-SAP
PHY layer
PLME-SAP
PLME (PHY PIB)
RF-SAP
•
•
•
•
•
•
MCPS – MAC Common Part Sublayer
PLME – PHY Layer Management Entity
MLME – MAC Sublayer Management Entity
RF – Radio Frequency
PIB – PAN Information Base
SAP – Service Access Point
Ubiquitous Computing,  Helmut Dispert
Ref.: www.elektroniknet.de
Fachbereich Informatik und Elektrotechnik
802.15.4
802.15.4 frame structures:
Each successive protocol layer adds to the structure with layerspecific headers and footers.
The standard defines four frame structures:
• A beacon frame, used by a coordinator to transmit beacons
• A data frame, used for all transfers of data
• An acknowledgment frame, used for confirming successful
frame reception
• A MAC command frame, used for handling all MAC peer entity
control transfers
Each layer of the protocol adds fields.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
Beacon frame and PHY packet
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
The 802.15.4 Beacon Frame,
used for synchronization of network nodes.
GTS – Guaranteed Time Slots
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
Data frame and PHY packet
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
Acknowledgment frame and PHY packet
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
Command frame and PHY packet
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
The 802.15.4 Command Frame
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 MAC Frame Formats
Option:
The 802.15.4 MAC Superframe Structure.
Used to reserve
timeslots for critical
applications.
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 MAC
Features
•
•
•
•
•
•
Beacon Management
Channel Access
Guaranteed Time Slot (GTS ) management
Frame Validation
Acknowledged Frame Delivery
Association/Dissassociation with PAN coordinator
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 MAC
Superframe Structure
•
•
•
•
•
•
Format defined by coordinator
Bounded by network beacons
Divided into 16 equally sized slots
Contention Access Period (CAP) – CSMA-CA
Contention Free Period (CFP) – GTS
Can allocate up to 7 GTSs, each longer than 1 time slot
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 – Beacon Mode
GTS 3
GTS 2
GTS 1
15ms * 2n
where 0 ≥ n ≥ 14
Network
beacon
Transmitted by network coordinator. Contains network information,
frame structure and notification of pending node messages.
Beacon
extension
period
Space reserved for beacon growth due to pending node messages
Contention
period
Access by any node using CSMA-CA
Guaranteed
Time Slot
Reserved for nodes requiring guaranteed bandwidth [n = 0].
Ref.: http://www.cens.ucla.edu/sensys03/sensys03-callaway.pdf
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 MAC
Details
•
•
•
•
•
•
Beacons transmitted at start of slot 0 without CSMA
CAP starts immediately after Beacon
CFP starts on slot boundary immediately following CAP
CFP extends to end of active period
Devices can sleep during inactive period until next
beacon
PANs not wishing to use Superframe structure always
use unslotted CSMA-CA to access channel and are
always active
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Three types of data transfer exist:
• Coordinator to Device
• Device to Coordinator
• Between peer devices
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Coordinator to Device
Device to Coordinator
Network
Device
Coordinator
Beacon
Network
Device
Coordinator
Beacon
Beacon Enabled Mode
Data Request
Acknowledgement
Data
Data
Acknowledgement
Acknowledgement
(optional)
Network
Device
Coordinator
Network
Device
Coordinator
Data Request
Acknowledgement
Data
Acknowledgement
Non-Beacon Enabled Mode
Data
Acknowledgement
(optional)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Coordinator to Device (Beacon-Enabled)
•
•
•
•
•
Coordinator indicates in beacon message that data pending
Device requests data using slotted CSMA-CA
Coordinator acknowledges request
Data sent from coordinator to device
Device acknowledges data sent
Network
Device
Coordinator
Beacon
Data Request
Acknowledgement
Data
Acknowledgement
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Coordinator to Device (NonBeacon-Enabled)
• Coordinator stores pending data and waits for request
• Device requests data using unslotted CSMA-CA at applicationdefined rate
• Coordinator acknowledges request
• Data sent from coordinator to device
• Device acknowledges data sent
Network
Device
Coordinator
Data Request
Acknowledgement
Data
Acknowledgement
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Device to Coordinator (Beacon-Enabled)
• Device listens for network beacon
• When found, synchronizes to superframe structure
• At right time it transmits its data frame using slotted CSMACA to coordinator
• Space for optional acknowledgements at end of slot
Network
Device
Coordinator
Beacon
Data
Acknowledgement
(optional)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Device to Coordinator (NonBeacon-Enabled)
• Simply transmits data frame using unslotted CSMA-CA
Network
Device
Coordinator
Data
Acknowledgement
(optional)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Peer to Peer (NonBeacon-Enabled)
• Any device communicates with any other within its
transmission radius
• Asynchronous – always on, use CSMA-CA
• Synchronous – duty cycle to save power, still use
CSMA-CA
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Association/Disassociation with PAN
•
•
•
•
Devices scan channel to find PANs within range
List of available PANs for association generated
How to choose a suitable PAN with which to associate is
up to the application
Coordinator decides to release device from PAN
– Sends disassociation notification command to device
– Device sends ack that it has disassociated itself
•
Device decides to release itself from PAN
– Sends disassociaton notification command to coordinator
– Coordinator sends ack that it has disassociated device
•
Both devices and coordinator remove all references of
each other
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Synchronisation
•
Beacon-Enabled
– Synchronisation performed by receiving and decoding
beacon frames
•
NonBeacon Enabled
– Synchronisation performed by polling the coordinator for
data
•
Orphaned Devices
– Orphan notification commands to re-synchronise
– Timeout before device considered orphaned
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Data Transfer Model
Transmission/Reception/Ack
•
Beacon-Enabled Transmission
–
–
–
–
•
Transmitting device finds beacon before transmission
If not found, uses unslotted CSMA-CA to send
If found, transmits in appropriate portion of superframe
Transmissions in CAP use CSMA, in GTS no CSMA
Beacon-Enabled Reception
– Device determines that data for it is pending by examining
beacon message contents
– If data pending, sends request for that data to coordinator
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Example
Example: ZigBee – IEEE 802.15.4
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Sensor Networks
IEEE 802.15.4 and ZigBee Compliant RF Solution:
IEEE 802.15.4 and ZigBee are the only radio standards that
specifically address the requirements of wireless monitoring and
control systems. Proven and robust ZigBee compliant platforms,
consisting of hardware and software, are available and form a solid
basis for development of ZigBee certified products.
The ZigBee specification was ratified by the ZigBee Alliance in
December 2004. It is an open and global standard for low-cost, lowpower wireless embedded networking.
Not true anymore today:
Other standards exist, e.g. Z-Wave, ANT, etc.
Ref.: Chipcon
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee?
"Some people say ZigBee got its name from the
way bees zig and zag while tracking between
flowers and relaying information to other bees
about where to find resources (router bees!)."
It is designed for mesh networking.
The applications are targeted toward groups of unattended
wireless systems in homes, offices, and factories. ZigBee is
optimized for low-cost, low-power systems.
http://www.circuitcellar.com/library/print/0205/Cross175/2.htm
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee
Objectives
What is ZigBee?
• Open global standard to enable reliable, cost-effective, low-power,
wirelessly networked, monitoring and control products
• specification for low data-rate wireless connectivity with fixed, portable
and moving devices with no battery or very limited battery consumption
requirements typically operating in the POS of 10m
• a longer range at a lower data rate may be an acceptable trade-off?
ZigBee protocol stack
• ZigBee has added to 802.15.4 by defining the network layer of the ZigBee
stack to support star, mesh and hybrid networking
• Network management that allows certain node types to sleep most of the
time to conserve power
Possible applications
• A wide range of products and applications across consumer, commercial,
industrial and government markets world wide
• Focus on remote monitoring and
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee
ZigBee Features
§ Ad-hoc self forming networks
- Mesh, Cluster Tree and Star Topologies
- Reliable broadcast messaging
- Non-guaranteed message delivery
§ Logical Device Types
- Coordinator, Router and End Device
§ Applications
-
Device and Service Discovery
Optional acknowledged service
Messaging with optional responses
Mechanism to support mix of Public and Private profiles in
the same network, all supported by standard ZigBee
network and application features
continued
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee
ZigBee Features
§ Security
- Symmetric Key with AES-128
- Authentication and Encryption at MAC, NWK and
Application levels.
- Key Hierarchy: Master Keys, Network Keys and Link Keys
§ Qualification
- Conformance Certification (Platform and Logo)
- Interoperability Events
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Sensor Networks
IEEE 802.15.4 and ZigBee Compliant RF Solution:
IEEE 802.15.4 and ZigBee are the only radio standards that
specifically address the requirements of wireless monitoring and
control systems. Proven and robust ZigBee compliant platforms,
consisting of hardware and software, are available and form a solid
basis for development of ZigBee certified products.
The ZigBee specification was ratified by the ZigBee Alliance in
December 2004. It is an open and global standard for low-cost, lowpower wireless embedded networking.
NEC's ZigBee technology (Credit: NEC)
Ref.: Chipcon
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Comparison
Radio Technologies:
Comparison between ZigBee, Bluetooth and Wi-Fi
Standard
ZigBee
(802.15.4)
Bluetooth
(802.15.1)
Wi-Fi
(802.11)
Transmission range (m)
1 - 100
1 - 10
1 - 100
Battery Life (days)
100 - 1000
1-7
½-5
Network Size (nodes)
65536
7
32
Stack size (kbyte)
4 - 32
250
1000
Throughput
< 250 kbps
< 2.2 Mbps
< 54Mbps
For sensor networks the best solution is ZigBee,
especially because of it's very low power consumption.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Comparison of wireless technologies
The 802 Wireless Space
WWAN
IEEE 802.22
Range
IEEE 802.20
WMAN
WIMAX
IEEE 802.16
WLAN
ZigBee
802.15.4
WPAN
0.01
WiFi
802.11
Bluetooth
802.15.1
0.1
1
10
Data Rate (Mbps)
802.
1
802. 5.3
1
802. 5.3a
15.3
c
100
1000
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Three tier structure of ZigBee
Application/Profiles
Application Framework
Network/Security
MAC Layer
PHY Layer
Ubiquitous Computing,  Helmut Dispert
User Defined
[APPLICATION]
ZigBee Alliance
[ZIGBEE PLATFORM]
Defined by IEEE 802.15.4
[SILICON]
Fachbereich Informatik und Elektrotechnik
Sensor Networks
ZigBee Stack:
Applications
End User
ZigBee is built on the
Application Profiles
robust PHY (Physical)
and MAC (Medium
Access Control) layers
defined by the IEEE
Application Framework
802.15.4 standard.
Above the PHY and MAC
layers ZigBee defines
Network and Security
mesh, peer-to-peer, and
Layers
cluster tree network
topologies with data
security features and
MAC Layer
interoperable application
profiles:
PHY Layer
Silicon
ZigBee Application Profiles
ZigBee Alliance
(ZigBee
Platform Stack)
ZigBee
compliant
platform
IEEE 802.15.4
(Silicon)
ZigBee Stack
Application
Ref.: Chipcon
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Application (APL) Layer
Application Framework
Endpoint 1
APSDE-SAP
Endpoint 0
APSDE-SAP
Application Support Sublayer (APS)
APS Security
Management
APS Message
Broker
Reflector
Management
NLDE-SAP
Network (NWK) Layer
IEEE 802.15.4
defined
ZigBee Alliance
defined
NWK Security
Management
Layer
Interface
Ubiquitous Computing,  Helmut Dispert
Routing
Management
Network
Management
NLDE-SAP
NLME-SAP
Medium Access Control (MAC) Layer
End Manufacturer
defined
Layer
Function
NWK Message
Broker
PD-SAP
PLME-SAP
Physical (PHY) Layer
2.4 GHz Radio
868/915 MHz Radio
NLME-SAP
Security
Service
Provider
ZDO Management Plane
Endpoint 240
APSDE-SAP
Application
Object 1
APSME-SAP
…
ZDO Public
Interfaces
Application
Object 240
ZigBee Device Object
(ZDO)
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Der 802.15.4-Standard bildet eine Implementierung der Bitübertragungs- und der Sicherungsschicht
(unten). Auf diesen setzt ZigBee auf. Der ZigBee Network Layer (NWK) übernimmt Aufgaben wie
Verwaltung der ZigBee-bezogenen Netzwerk-Topologie, des Routing und des
Sicherheitsmanagements. Das ZigBee Application Programming Interface stellt die Schnittstelle zu
den Anwendungen dar. Diese werden in sog. ZigBee-Profilen beschrieben. Hierbei kann es sich um
standardisierte Profile (wie Light Sensor oder Light Controller für einfache Schaltanwendungen)
oder um proprietäre Profile handeln.
Ref.: www.elektroniknet.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee
ZigBee Network Topology:
Applications for topology models
§ Cluster tree networks
- Employ multi-hop routing
- Can be very large:
255 clusters of 254 nodes each = 64,770 nodes
- May span physically large areas
- Suitable for latency-tolerant applications
Ref.: Andreas Riener, Johannes Kepler University, Linz, Austria
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee – Physical Layer
ISM band
§ The ISM (industrial, scientific and medical) radio bands were orig.
internationally reserved for (non-commercial) RF- (radio
frequency) applications for industrial, scientific and medical
purposes
§ Recently also used for license-free error-tolerant communication
applications like WLAN, Bluetooth, ZigBee
§ Possible frequencies: 900 Mhz, 2.4 Ghz band and 5.8 Ghz band
ZigBee transmission rates:
§ The 2400 Mhz (2.4 Ghz) frequency band is recognized as global
standard in almost any country (2400 to 2483,50 Mhz @ 250kbps)
§ The 868 Mhz band has been designed to use as fallback-band
(with lower data rate) in Europe (868 to 870 Mhz @ 20kbps)
§ The 915 Mhz band is used as fallback-band in (North-)America,
Australia, etc. (902 to 928 Mhz @ 40kbps)
Ref.: Andreas Riener, Johannes Kepler University, Linz, Austria
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee – Signal-to-Noise Ratio
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee – Comparison
Comparison of IEEE 802.15.4 Frequency Bands
Prescribed Values
Property Description
Raw data bit rate
915 MHz
2.4 GHz
40 kbps
250 kbps
Transmitter output power
Receiver sensitivity
1 mW = 0 dBm
-92 dBm
(<1% packet error rate)
Transmission range
-85 dBm
(<1% packet error rate)
Indoors: up to 30 m; Outdoors: up to 100 m
Latency
15 ms
Channels
10 channels
16 channels
Channel numbering
16 channels
11 to 26
Channel access
Modulation scheme
CSMA-CA and slotted CSMA-CA
BPSK
O-QPSK
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Comparison
RF Technologies:
Comparision between ZigBee, Bluetooth and Wi-Fi
Standard
ZigBee
(802.15.4)
Bluetooth
(802.15.1)
Wi-Fi
(802.11)
Transmission range (m)
1 - 100
1 - 10
1 - 100
Battery Life (days)
100 - 1000
1-7
½-5
Network Size (nodes)
65536
7
32
Stack size (kbyte)
4 - 32
250
1000
Throughput
< 250 kbps
< 2.2 Mbps
< 54Mbps
For sensor networks the best solution is ZigBee,
especially because of it's very low power consumption.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee
802.15.4 General Characteristics
§
§
§
§
§
§
Data rates of 250 kb/s, 40 kb/s and 20 kb/s.
Star or Peer-to-Peer operation.
Support for low latency devices.
Fully handshaked protocol for transfer reliability.
Low power consumption.
Frequency Bands of Operation
- 16 channels in the 2.4GHz ISM* band
- 10 channels in the 915MHz ISM band
- 1 channel in the European 868MHz band.
* ISM: Industrial, Scientific, Medical
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Sensor Networks
Comparison between ZigBee, Bluetooth and Wi-Fi
ZigBee
Battery Life
Battery Life
Network Size
Network Size
Throughput
Stack Size
Transmission range
Ubiquitous Computing,  Helmut Dispert
Bluetooth
Throughput
Stack Size
Transmission range
Wi-Fi
Fachbereich Informatik und Elektrotechnik
802.15.4 Application Space
§ Sensors & Controls:
-
Home Automation
Industrial Automation
Remote Metering
Automotive Networks
Interactive Toys
Active RFID/ asset tracking
Medical
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Sensor Networks
Sensor/Control Network Requirements
•
Large networks (large number of devices and large
coverage area) that can form autonomously and that will
operate very reliably for years without any operator
intervention
•
Very long battery life (years off of a AA cell), very low
infrastructure cost (low device & setup costs) and very
low complexity and small size
•
Device data rate and QoS needs are low
•
Standardized protocols are necessary to allow multiple
vendors to interoperate
Ref.: ZigBee Alliance
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee - Devices
ZigBee – device types/classes
ZigBee coordinator (ZC)
•
•
•
•
•
•
Acts as 802.15.4 PANC (personal area network coordinator)
The most capable device
Is the root of the network tree, initiates network formation
Capability of bridging to other networks
Exactly one ZC in a network
Enabled to store information about the network, including acting
as the repository for security keys
continued
Ref.: Andreas Riener, Universität Linz
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee - Devices
ZigBee – device types/classes
ZigBee routers (ZR)
•
•
•
•
•
•
Acts as 802.15.4 FFD (full function device)
Available in any topology
Capable of becoming a network coordinator, talking to any other
Typically continuously active looking for stimuli
Participates as an intermediary in multihoprouting for messages
ZR may associates with the ZC or with previously associated ZR
ZigBee end device (ZED)
•
•
•
•
•
Also known as RFD (reduced function device)
Limited to only star topologies (with ZC or ZR in the center)
Cannot become a network coordinator
Communicates only to a network coordinator (ZC, ZR)
Simple implementation, therefore efficient, low power
consumption
Ref.: Andreas Riener, Universität Linz
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Applications
ZigBee
IEEE 802.15.4 MAC
IEEE 802.15.4
868/915 MHz
PHY
Ubiquitous Computing,  Helmut Dispert
IEEE 802.15.4
2400 MHz
PHY
§
§
§
§
Packet generation
Packet reception
Data transparency
Power Management
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 PHY
Features
•
•
•
•
•
•
Activation/Deactivation of radio transceiver
Energy Detection (ED)
Link Quality Indication (LQI)
Channel Selection
Clear Channel Assessment (CCA)
Transmission/Reception of packets over physical
medium
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Applications
ZigBee
IEEE 802.15.4 MAC
IEEE 802.15.4
868/915 MHz
PHY
Ubiquitous Computing,  Helmut Dispert
IEEE 802.15.4
2400 MHz
PHY
§
§
§
§
Channel acquisition
Contention management
NIC address
Error Correction
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4
MAC Overview
Design Drivers
Simple but flexible protocol
§
§
§
§
§
Extremely low cost
Ease of implementation
Reliable data transfer
Short range operation
Very low power consumption
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
IEEE 802.15.4 / ZigBee Network:
requires at least one full function device as a
network coordinator, but endpoint devices may
have reduced functionality.
§ ZigBee supports two types of addresses:
- 64 bit IEEE addresses
(18.446.744.073.709.551.616 possibilities)
- Short (16 bit) addresses can be allocated to reduce
packet size (65.536 possibilities)
§ Addressing modes:
- Network + device indentifier (star)
- Source/destination identifier (peer – peer)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee Network Topologies
§ Star
networks support a single ZigBee coordinator with one or more ZigBee
End Devices (up to 65,536 in theory)
§ Cluster tree
networks provide for a beaconing multi-hop network
- Permits battery management of coordinator and routers
- Must tolerate high latency due to beacon collision avoidance
- Must use “netmask” type tree routing
§ Mesh
network routing permits path formation from any source device to any
destination device
- Radio Receivers on coordinator and routers must be on at all times
- Employs ZigBee joint routing solution including tree and table
driven routing
- Table routing employs a simplified version of Ad Hoc On Demand
Distance Vector Routing (AODV). This is an Internet Engineering
Task Force (IETF) Mobile Ad Hoc Networking (MANET) submission
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
MAC Overview - Star Topology
PAN Coordinator
Master/Slave
Full function device (FFD)
Reduced function device (RFD)
Communication flow
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
MAC Overview - Peer-Peer Topology
Cluster tree
Point to point
Full function device (FFD)
Reduced function device (RFD)
Communication flow
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Topologies
Cluster tree network:
•
•
very useful for larger networks
disadvantage: in case of a node fail all the tree behind the
node are cut off the network
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
MAC Overview - Combined Topology
Clustered stars:
for example, cluster nodes
exist between rooms of a
hotel and each room has a
star network for control.
Ubiquitous Computing,  Helmut Dispert
Full function device (FFD)
Reduced function device (RFD)
Communication flow
Fachbereich Informatik und Elektrotechnik
Topologies
Mesh network:
a) fully meshed network
b) Partially meshed network
Main features of meshed networks:
• self-configuration of network
• no pre-defined data routes
• self organization (and self healing) of network
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee Network Communication Model (Tree)
ZigBee Coordinator (FFD)
ZigBee Router (FFD)
ZigBee End Device (RFD or FFD)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee Network Communication Model (Mesh)
ZigBee Coordinator (FFD)
ZigBee Router (FFD)
ZigBee End Device (RFD or FFD)
Star Link
Mesk Link
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Topologies
Industry application of
Sensor Networks
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Topologies
Point-to-point
Star network:
point-to-multipoint
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Topologies
Cluster tree network
in industrial applications
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
MAC Overview - Traffic Types
• Periodic data
– Application defined rate (e.g. sensors)
• Intermittent data
– Application/external stimulus defined rate (e.g. light switch)
• Repetitive low latency data
– Allocation of time slots (e.g. mouse)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Applications
ZigBee
IEEE 802.15.4 MAC
IEEE 802.15.4
868/915 MHz
PHY
Ubiquitous Computing,  Helmut Dispert
IEEE 802.15.4
2400 MHz
PHY
§
§
§
§
Network Routing
Address translation
Packet Segmentation
Profiles
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Applications
ZigBee
IEEE 802.15.4 MAC
IEEE 802.15.4
868/915 MHz
PHY
Ubiquitous Computing,  Helmut Dispert
IEEE 802.15.4
2400 MHz
PHY
• Application-support
(APS) sub-layer
• ZigBee Device Objects
(ZDO)
• Application Objects
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Application (APL) Layer
Application Framework
Endpoint 1
APSDE-SAP
Endpoint 0
APSDE-SAP
Application Support Sublayer (APS)
APS Security
Management
APS Message
Broker
Reflector
Management
NLDE-SAP
Network (NWK) Layer
IEEE 802.15.4
defined
ZigBee Alliance
defined
NWK Security
Management
Layer
Interface
Ubiquitous Computing,  Helmut Dispert
Routing
Management
Network
Management
NLDE-SAP
NLME-SAP
Medium Access Control (MAC) Layer
End Manufacturer
defined
Layer
Function
NWK Message
Broker
PD-SAP
PLME-SAP
Physical (PHY) Layer
2.4 GHz Radio
868/915 MHz Radio
NLME-SAP
Security
Service
Provider
ZDO Management Plane
Endpoint 240
APSDE-SAP
Application
Object 1
APSME-SAP
…
ZDO Public
Interfaces
Application
Object 240
ZigBee Device Object
(ZDO)
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
Interface to outside world:
Sensor transducers
User interface
Microcontroller
code
including ZigBee
802.15.4
Transceiver IC
ZigBee provides network
structure, routing, and
security, while the more basic
physical and MAC layers are
provided by IEEE 802.15.4.
http://www.circuitcellar.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4 / ZigBee Architecture
• Application-support (APS) sub-layer
– Maintains binding tables: a match between devices based on their
services and their needs
Node 2
– Forwarding messages between bound devices
Node 1
Multiple subunits (up to 240) in a single
node (physical devices, e.g. sensors,
switches, lamps etc.)
Node subunits are modeled with
Application Objects (AOs)
Device Descriptors
• ZigBee Device Objects (ZDO)
ZigBee Device Profile
– Defines device role (coordinator or end device)
(Application Profile).
– Initiating and/or responding to binding requests
– Establish secure relationship between devices
– Discovering other devices on the network and determining which
application services they provide
• Application Objects
– Application implementation according to the ZigBee-defined
application descriptions
– User code!
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Device
Applying ZigBee
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Applications
Energy Management and Comfort Functions:
• Thermostats
• Heating, ventilation, air-conditioning (HVAC)
• Control of blinds/shades/rollers/windows
Lighting Control Systems:
• Power outlets
• Dimmers
• Switches
• Remote Controls
Environmental and Agricultural Monitoring:
• Temperature
• Carbon dioxide
• Humidity
• pH, Salinity
• Vibration
Industrial:
• Industrial plant monitoring and control
• Wireless embedded sensor networks
in general
• Inventory control
• Asset tracking
Automatic Meter Reading Systems:
• Electricity
• Gas
• Water
Health Care / Medical:
• Patient Monitoring
Alarm and Security Systems:
• Home security
• Smoke detectors
• Burglary and social alarms
• Access control with location detection
• Water leakage systems
Consumer Electronics:
• Remote Controls
• ZigBee enabled mobile phones, e.g.
supporting general remote control
functionality
• Set-Top boxes
• PC-peripherals
Ref.: Chipcon
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Applications
Energy Management and Comfort Functions:
• Thermostats
• Heating, ventilation, air-conditioning (HVAC)
• Control of blinds/shades/rollers/windows
Lighting Control Systems:
• Power outlets
• Dimmers
• Switches
• Remote Controls
Environmental and Agricultural Monitoring:
• Temperature
• Carbon dioxide
• Humidity
• pH, Salinity
• Vibration
Industrial:
• Industrial plant monitoring and control
• Wireless embedded sensor networks
in general
• Inventory control
• Asset tracking
Automatic Meter Reading Systems:
• Electricity
• Gas
• Water
Health Care / Medical:
• Patient Monitoring
Alarm and Security Systems:
• Home security
• Smoke detectors
• Burglary and social alarms
• Access control with location detection
• Water leakage systems
Consumer Electronics:
• Remote Controls
• ZigBee enabled mobile phones, e.g.
supporting general remote control
functionality
• Set-Top boxes
• PC-peripherals
Ref.: Chipcon
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee - Example
Example:
VitaSENS
ZigBeeTM – Sensor Network:
Wireless transmission of vital body
parameters.
Video
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Device
Building ZigBee compatible devices
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee Device
Microcontroller
RF Data Modem
RX
analog/RF
RX
baseband
Sensor
appl.
Frequency
generator
SPI/
control
ZigBee
NWK
TX
analog/RF
TX
baseband
15.4 MAC
Power Management
Typical ZigBee device:
• Microcontroller
• RF IC
• Interface to sensors or actuators
Ubiquitous Computing,  Helmut Dispert
Sensor
driver
Sensor
or
Actuator
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee related components, chip sets, products, etc.
Renesas
Development Kit
Microcontroller: M16C
Renesas: Mitsubishi, Hitachi, NEC
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee related components, chip sets, products, etc.
ZMD
Development Kit
http://www.zmd.de
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee related components, chip sets, products, etc.
Silicon Labs
Development Kit
http://www.silabs.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
IEEE 802.15.4 Summary
ZigBee related components, chip sets, products, etc.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Excursion
Excursion:
à Renesas µC
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas
Ref.: http://documentation.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas
Ref.: http://documentation.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas
Ref.: http://documentation.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
M16C Family Product Range
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
Renesas ZigBee solution and MAC solution.
ZigBee evaluation kit.
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Excursion
End Excursion
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
Renesas ZigBee
The Renesas ZigBee system is a comprehensive platform
that accelerates the development of reliable, cost-effective
low-data-rate wireless applications.
It includes a robust 16-bit M16C microcontroller, IEEE
802.15.4 standards-based radios, a ZigBee software stack,
media access control (MAC) software, real-time operating
system (RTOS), and an integrated development
environment.
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
900MHz ZDK Board
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
RF Sniffer Interface
RF Sniffer Connectivity
Connected to RF Sniffer Board
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Renesas - ZigBee
RF Sniffer Connectivity
Ref.: http://resource.renesas.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Atmel - ZigBee
MeshNetics – ZigBit (now Atmel)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Atmel - ZigBee
ZigBit – Antenna models
for PCB or
external antenna
Ubiquitous Computing,  Helmut Dispert
with
Dual Chip antenna
Fachbereich Informatik und Elektrotechnik
Atmel - ZigBee
MeshNetics
Pattern: Symmetric Dipole Antenna (horizontal plane)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Atmel - ZigBee
MeshNetics
Pattern: Symmetric Dipole Antenna (horizontal plane)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee – Target Markets
·
·
·
·
Monitors
Sensors
Automation
Control
Consumer
Electronics
Industrial &
Commercial
·
·
·
·
·
TV
VCR
DVD
CD
Remote
PC
Peripherals
·
·
·
Low Data Rate
Radio Devices
Personal
Healthcare
·
·
·
·
Monitors
Diagnostics
Sensors
Toys &
Games
·
·
·
PETs
Gameboys
Educational
Home
Automation
·
·
·
·
Mouse
Keyboard
Joystick
Gamepad
Security
HVAC
Lighting
Closures
Ref.: Philips, Semiconductors Division
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Standards Expectations
Market Expectations
This will satisfy
all requirements
ZigBee today
Disillusionment
Everything
is OK
Products
start to ship
Market
Interest
Builds
Obituaries
Written
Time
Ubiquitous Computing,  Helmut Dispert
Ref.: Philips, Semiconductors Division
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC View
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC Examples
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC Solution
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC Solution
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC Solution
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee-Applications: NEC Solution
Ref.: http://www.necel.com/micro/en/technology/zigbee/
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Siemens
APOGEE Wireless Field Level Network,
Wireless Building Automation System
Industry’s first (2005)
wireless building automation
system (BAS) using ZigBee
technology.
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
ZigBee - Example
Example:
Pimpstar LED Car Rims
Rims are programmable using a laptop and can display images
as the car rolls down the street.
Video
Example 2:
MonkeyLectric Video Pro bike wheel light display
Video
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Applications
Videos
Wireless Sensor Networks
ZigBee
•
•
•
•
•
•
Sensornets_BZAKA-IKTI
Expand GPIO with Zigbee Transceiver
Time Division Beacon Scheduling
ZigBee Network
Zigbee Application for Home Appliance
ZigBee PRO network with BitCloud
Ubiquitous Computing,  Helmut Dispert
Video
Video
Video
Video
Video
Video
Fachbereich Informatik und Elektrotechnik
Zigbee Routing Layer
• Hierarchical routing strategy
• Two strategies
- AODV: Ad Hoc On Demand Distance Vector
- Cluster-Tree algorithm from Motorola
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Ad Hoc On Demand Distance Vector
• Pure on-demand route acquisition algorithm
– Defines path of message from source to sink
– Nodes not on active path don’t maintain routing
information or exchange routing tables
• Primary objectives
– Broadcast discovery packets only when necessary
– Distinguish between local connectivity management
and general topology management
– Disseminate information about local connectivity
changes to neighbouring mobile nodes
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Ad Hoc On Demand Distance Vector
Reverse and Forward path information in AODV
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Cluster-Tree Algorithm
•
•
•
•
•
Protocol of logical link and network layers
Forms single/multi cluster tree networks
Forms self-organizing network with redundancy and selfrepair capabilities
Nodes select cluster heads and form clusters in a selforganized manner.
Self-developed clusters then connect to each other through a
designated Device (DD)
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Cluster-Tree Algorithm
Multi cluster network with DD (designated device) border nodes
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Summary
IEEE 802.15.4 WPAN
•
•
Defines standard for low power, low data rate networks
Defines network topologies that should be supported
IEEE 802.15.4 PHY
•
Physical layer specification of standard
IEEE 802.15.4 MAC
•
MAC specification of standard
Zigbee Routing Layer
•
Routing layer on top of PHY and MAC, enabling support
for the “star, mesh, and cluster-tree” network topologies
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
802.15.4
Stack implementation:
à IEEE 802.15.4
à ZigBee
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Atmel
Atmel
certified IEEE 802.15.4-compliant
software stacks,
http://www.atmel.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
BitCloud Architecture
Software Stack Architecture.
BitCloud internal architecture
follows the suggested separation of
the network stack into logical layers
as found in IEEE 802.15.4 and
ZigBee.
Besides the core stack containing
protocol implementation, BitCloud
contains additional layers
implementing shared services (e.g.
task manager, security, and power
manager) and hardware
abstractions (e.g. hardware
abstraction layer (HAL) and board
support package (BSP)).
http://www.atmel.com
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
BitCloud Architecture
The topmost of the core stack layers, APS, provides the highest level of networking-related
API visible to the application.
ZDO provides a set of fully compliant ZigBee Device Object API which enable main
network management functionality (start, reset, formation, join). ZDO also defines ZigBee
Device Profile types, device and service discovery commands implemented by the stack.
There are three service vertical components including: task manager, security, and power
manager. These services are available to the user application, and may also be utilized by
lower stack layers.
Task manager is the stack scheduler which mediates the use of the MCU among internal
stack components and user application. The task manager implements a priority based cooperative scheduler specifically tuned for multi-layer stack environment and demands of
time-critical network protocols.
Power management routines are responsible for gracefully shutting down all stack
components and saving system state when preparing to sleep and restoring system state
when waking up.
Hardware Abstraction Layer (HAL) includes a complete set of APIs for using on-module
hardware resources (EEPROM, sleep, and watchdog timers) as well as the reference
drivers for rapid design-in and smooth integration with a range of external peripherals
(IRQ, TWI, SPI, USART, 1-wire).
Board Support Package (BSP) includes a complete set of drivers for managing standard
peripherals (sensors, UID chip, sliders, and buttons) placed on a development board.
http://www.atmel.com - BitCloud User Guide
Ubiquitous Computing,  Helmut Dispert
Fachbereich Informatik und Elektrotechnik
References
IEEE Std 802.15.4 - 2003
BitCloud Quick Start Guide
BitCloud User Guide
Ubiquitous Computing,  Helmut Dispert