Transcript The IEEE 802.15.4 (Low Rate Wireless Personal Area Network) Standard Lance Hester Ken Cornett Florida Communication Research Lab Motorola Labs May 20, 2002 IEEE 802.15.4 Standard.

The IEEE 802.15.4 (Low Rate Wireless
Personal Area Network) Standard
Lance Hester
Ken Cornett
Florida Communication Research Lab
Motorola Labs
May 20, 2002
IEEE 802.15.4 Standard
IEEE What?
IEEE 802 LAN/MAN Standards Committee
…
…
…
802.1
802.11
Higher Layer
… Wireless Local …
LAN Protocols
Area Network
Working Group
Working Group
TG1
WPAN/Bluetooth
Task Group
TG2
Coexistence
Task Group
802.15
Wireless Personal
Area Network
Working Group
TG3
WPAN High Rate
Task Group
…
802.17
Resilient
Packet Ring
Working
Group
TG4
WPAN Low Rate
Task Group
Formed in November, 2000
Florida Communication Research Lab
20 May 2002
2
IEEE 802.15.4-
What it is:




An WPAN standard
optimized for low (0.01115.2 kb/s) data
throughput applications
with simple QoS
requirements
Lower power, lower cost
than other WPANs (e.g.,
Bluetooth)
Capable of multiple
network types (star,
cluster tree, etc.)
Using ZigBee
Consortium for
marketing and
compliance (like
WECA/Wi-Fi/802.11b)
Florida Communication Research Lab

What it is not:




A WLAN
A Bluetooth™
replacement (e.g., no
isochronous voice
capability)
Optimized for multimedia,
TCP/IP, or other high data
rate applications
A system, network, or
application set
20 May 2002
3
802.15.4 Physical Layers

2.4 GHz:







250 kb/s raw data rate, 1 Mc/s chip rate
Chips: O-QPSK with half-sine shaping (a.k.a. MSK)
Data: 16-ary orthogonal modulation
16 channels; 5 MHz channel separation
-85 dBm sensitivity @ 1% PER (20 byte packets)
Variable length payload size dependent upon addressing
868 (915- U.S.) MHz:





20 (40) kb/s raw data rate, 300 (600) kc/s chip rate
Chips: BPSK with raised-cosine shaping
Data: differential BPSK
1 (10) channels; 2 MHz channel separation @ 915 MHz
-92 dBm sensitivity @ 1 % PER (20 byte packets)
Florida Communication Research Lab
20 May 2002
4
802.15.4 Physical Characteristics



Transmission Range
 ~ 10 meters indoors; ~ 30 meters outdoors @ Tx-Power = - 3 dBm (0.5 mW)
 Maximum regulated transmit power levels
Frequency Band
Geographical
Region
Max. conductive
power/ Radiated
field limit
Regulatory
Document
2.4 GHz
Japan
10 dBm (10 mW)
ARIB STD-T66
Europe (except
Spain and France)
20 dBm (100 mW)
EIRP or 10 dBm
(10 mW) /MHz
peak power
density
ETS 300- 328
USA
30 dBm (1000 mW)
47 CFR 15.247
902-928 MHz
USA
30 dBm (1000 mW)
47 CFR 15.247
868 MHz
Europe
14 dBm (25 mW)
ETS 300-220
Power Consumption < 100 A
 Expected duty cycle of 1% and low power operation (under 0 dBm [1mW])
Power Supply
 AA battery
 Lifetime approx. 1 year
Florida Communication Research Lab
20 May 2002
5
802.15.4 Physical Characteristics

Bi-directional communication supported



Uni-directional communication not supported
All messages are acknowledged
DSSS modulation mitigates multipath interference
 “1000 ns” chip length >> 30 ns propagation delay
Florida Communication Research Lab
20 May 2002
6
Chip Set information

Yes! There is IC development for the 802.15.4
Florida Communication Research Lab
20 May 2002
7
802.15.4 Medium Access Control (MAC)
Features

Extremely flexible support:

Star, cluster tree, other network topologies, with optional
network beacon



Slotted Access CSMA-CA
Superframe period switchable from 15 ms to > 4 minutes


Trade power consumption, message latency, and throughput
Optional guaranteed time slots in superframe


Application flexibility
Low-latency applications (e.g., mice, wireless gaming)
Low duty cycle:

Can be < 0.1%
Low power consumption
 Good coexistence with other services

Florida Communication Research Lab
20 May 2002
8
802.15.4 MAC Super Frame Structure
Beacon
Contention Access Period
Contention
Free Period
GTS 1
Beacon
GTS 2
Super Frame Duration
Network
Beacon
Contention
Period
Allocated
slot
Transmitted by nodes. Contains network information,
super frame structure, and notification of pending
messages
Access by any node using CSMA-CA
Reserved for nodes requiring guaranteed bandwidth
Florida Communication Research Lab
20 May 2002
9
Node Types Supported

Distribution node


Controls the network topology at that node
Master/coordinator or mediation device



Stores routing information
Talks to other distribution and slave nodes
Slave node


Cannot control the network
Very simple implementation


Does not store routing information
Talks only to a distribution node
Florida Communication Research Lab
20 May 2002
10
Related technology
Network Scalability
Low latency
intensive
High
802.3 - ‘Wired Ethernet’
Fixed
Intended for
high power
apps
Cost
Fixed & Wireless
802.11b - ‘Wi-Fi’
Moderate
Bluetooth
802.15.4
M2M
Low
100
102
104
106
Area (meters2)
To complex for lowrate low-power
apps
Florida Communication Research Lab
Data Rate (Mbps)
100
802.11x
802.3
802.15.3
802.11a
10
1
4G
802.11b
Transitions from
Wired to Wireless
“Bluetooth”
802.15.1
Evolution Path with
Sustaining Innovation
3G
2.5G
0.1 PSTN
1G
1980
802.15.4
2G
1990
Variable
w/ Duty
Cycle
2000
2010
20 May 2002
11
How Does 802.15.4 Match Up?
Surveyed Wireless Sensor IEEE 802.15.4 Provisions
Wants
Low data rates
Data rates  115.2 kb/s
Usage of unlicensed frequency
ISM band operation
Long battery life
Low duty cycle operation  Low power
consumption
Low cost devices
Standard for ultra low cost and low
complex devices
Architecture which adapts to
accommodate various node types
Platform for various networking
schemes and supports multiple node
types (e.g. distribution and slave nodes)
Market acceptance
Member of well known 802 family
Florida Communication Research Lab
20 May 2002
12