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Robot Sensor Networks
HanyangUniversity
ZigBee
802.15.4 and the ZigBee Alliance
Motorola 802.15.4/ZigBee™ Platform
Robot Sensor Networks
HanyangUniversity
Contents
1. The ZigBee Alliance and 802.15.4
2. Features of Protocol Stack
3. ZigBee and Bluetooth
4. Reliability Throughout the Stacks
5. Robustness Throughout the Stacks
6. 802.15.4/ZigBee vs. Bluetooth
7. Motorola 802.15.4/ZigBee™ Platform
8. An Application Example
Robot Sensor Networks
HanyangUniversity
The ZigBee Alliance and 802.15.4
1. The ZigBee Alliance is
A consortium of end users and solution providers, primarily responsible for
the development of the 802.15.4 standard
Developing applications and network capability utilizing the 802.15.4 packet
delivery mechanism
Addresses application and interoperability needs of a substantial part of the
market
2. IEEE 802.15.4
Composed of many of the individuals and companies that make up the
ZigBee Alliance
Developed the basic PHY and MAC standard with the requirement that 15.4
be simple and manageable and that high‐level functionality (networking,
security key management, applications) be considered
Robot Sensor Networks
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ZigBee (1/2)
1. ZigBee is designed to be a low power, low cost, low data rate, wireless
solution.
2. ZigBee relies upon the robust IEEE 802.15.4 PHY/MAC to provide
reliable data transfer in noisy, interference‐rich environments
3. ZigBee layers on top of 15.4 with Mesh Networking, Security, and
Applications control
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ZigBee (2/2)
1. ZigBee Value Propositions
Addresses the unique needs of most remote monitoring and control network
applications
1) Infrequent, low rate and small packet data
Enables the broad‐based deployment of wireless networks with low cost &
low power solutions
1) Example: Lighting, security, HVAC,
2) Supports peer‐to‐peer, star and mesh networks
Monitor and sensor applications that need to have a battery life of years on
alkaline batteries
1) Example – security systems, smoke alarms
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What is the ZigBee Alliance?
1. Organization defining global standards for reliable, cost‐effective, low
power wireless applications
2. A rapidly growing, worldwide, non‐profit industry consortium of
Leading semiconductor manufacturers
Technology providers
OEMs
End‐users
3. Sensors are one of the reasons for ZigBee!
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What is ZigBee technology?
1. Cost‐effective, standards‐based wireless networking solution
2. Developed for and targets applications that need
Low to moderate data rates and low duty cycles
Low average power consumption / long battery life
Security and reliability
Flexible and dynamic network topologies
1) Star, cluster tree and mesh networks
Interoperable application frameworks controlled by an industry alliance to
ensure interoperability/compatibility
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The ZigBee Alliance Solution
1. Targeted at
Industrial and Commercial control/monitoring systems
Wireless sensor systems
Home and Building automation and controls
Medical monitoring
Consumer electronics
PC peripherals
2. Industry standard through application profiles running over IEEE802.15.4 radios
3. Primary drivers
Simplicity
Long battery life
Networking capabilities
Reliability
Low cost
4. Alliance member companies provide interoperability and certification testing
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Why do we need ZigBee technology?
1. ONLY standards‐based technology that
Addresses the unique needs of most remote monitoring and control and
sensory network applications
Enables the broad‐based deployment of wireless networks with low cost, low
power solutions
Provides the ability to run for years on inexpensive primary batteries for a
typical monitoring application
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1. Submission Title: [What You Should Know about the ZigBee Alliance]
2. Date Submitted: [24 September 2003
3. Source: [Jon Adams] Company [Motorola]
4. Address [2100 E Elliott Rd, Tempe AZ 85254]
5. Voice:[480‐413‐3439], FAX: [480‐413‐4433], E‐Mail:[[email protected]]
6. Re: [Sensors Expo Workshop]
7. Abstract: [Description of measures used to enhance reliability in IEEE
802.15.4/ZigBee]
8. Purpose: [Point of discussion for the Sensors Expo]
9. Notice: This document has been prepared to assist the ZigBee Alliance. It is offered
as a basis for discussion and is not binding on the contributing individual(s) or
organization(s). The material in this document is subject to change in form and
content after further study. The contributor(s) reserve(s) the right to add, amend or
withdraw material contained herein.
10. Release: The contributor acknowledges and accepts that this contribution will be
posted in the member area of the ZigBee web site.
ZigBee Alliance
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Commercial Building Automation
Industrial Plant Monitoring
Home Automation
Commercial Building Automation
Industrial Plant Monitoring
Home Automation
Home Controls Lighting (since abandoned)
Application Profiles Supported
No frame compatibility with “ZigBee” or “ZigBee‐Pro”
8 bit clusters, KVP/MSG services
Joint routing
CSKIP addresses
Coordinator binding
Spec:
December 2004
Platform test: March 2005
Currently shipped by all platform suppliers!
“ZigBee V1.0”, “r06”
(sometimes referred
to as Home
Controls V0)
Frame compatibility with ZigBee expected without optional new features
No frame compatibility with “ZigBee V1.0”
No compatibility with “ZigBee” networks
Same as “ZigBee” stack, plus or minus:
Mutlicast (+)
Many to one (source) routing (+)
Fragmentation (+)
AODV‐jr routing only (‐)
New address assignment
Spec:
December 2006 (est)
Platform test:
January 2007 (est)
Please note: Past experience would say this is 6 months after the specification is complete, June 2007
“ZigBee‐Pro” stack
(formerly known as
Commercial,
Industrial,
Institutional)
Frame compatibility with ZigBee‐Pro expected
No frame compatibility with “ZigBee V1.0”
No compatibility with “ZigBee‐Pro” networks
16 bit clusters, KVP/MSG services removed
Joint routing with CSKIP addresses
Coordinator binding optional
ZigBee cluster library
Spec:
August 2006 (est)
Platform test:
August 2006 (est)
“ZigBee” stack
(formerly known as
Home Controls V1)
CompatibilityFeature summaryRelease date and statusStack Version
ZigBee Stack Release Matrix
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Architecture Objectives
1. Enables cost‐effective, low power, reliable devices for monitoring and
control
2. ZigBee’s architecture developed to target environments and applications
best suited to the technology
3. Provide a platform and implementation for wirelessly networked devices
4. Ensure interoperability through the definition of application profiles
5. Define the ZigBee network and stack models
6. Provide the framework to allow a separation of concerns for the
specification, design, and implementation of ZigBee devices
7. Allow future extension of ZigBee
ZigBee Architecture Objectives
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ZigBee Feature Set
1. ZigBee V1.0
Ad‐hoc self forming networks
1) Mesh, Cluster Tree and Star
Logical Device Types
1) Coordinator, Router and End Device
Applications
1) Device and Service Discovery
2) Messaging with optional responses
3) Home Controls Lighting Profile
4) General mechanism to define private Profiles
Security
1) Symmetric Key with AES‐128
2) Authentication and Encryption at MAC, NWK and Application levels
3) Master Keys, Network Keys and Link Keys
Qualification
1) Conformance Certification (Platform and Profile)
2) Interoperability Events
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How A ZigBee Network Forms
1. Devices are pre‐programmed for their network function
Coordinator scans to find an unused channel to start a network
Router (mesh device within a network) scans to find an active channel to join,
then permits other devices to join
End Device will always try to join an existing network
2. Devices discover other devices in the network providing complementary
services
Service Discovery can be initiated from any device within the network
3. Devices can be bound to other devices offering complementary services
Binding provides a command and control feature for specially identified sets
of devices
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ZigBee Address Architecture
1. Addressing
Every device has a unique 64 bit MAC address
Upon association, every device receives a unique 16 bit network address
Only the 16 bit network address is used to route packets within the network
Devices retain their 16 bit address if they disconnect from the network,
however, if the LEAVE the network, the 16 bit address is re‐assigned
NWK broadcast implemented above the MAC:
1) NWK address 0xFFFF is the broadcast address
2) Special algorithm in NWK to propagate the message
3) “Best Effort” or “Guaranteed Delivery” options
4) Radius Limited Broadcast feature
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Packet Structure
1. Packet Fields
Preamble (32 bits) ‐ synchronization
Start of Packet Delimiter (8 bits) ‐ specifies one of 3 packet types
PHY Header (8 bits) ‐ Sync Burst flag, PSDU length
PSDU (0 to 127 bytes) ‐ Data
Preamble
Start ofPacketDelimiter
PHYHeader
PHY ServiceData Unit (PSDU)
6 Bytes 0‐127 Bytes
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General Data Packet Structure
PRE SPD LEN PC CRCLink Layer PDUADDRESSING
Preamble sequence
Start of Packet Delimiter
Length for decoding simplicity
Flags specify addressing mode
Data sequence number
CRC‐16
DSN
Addresses according to specified mode
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ZigBee Network Model
ZigBee End Device (RFD or FFD)
ZigBee Router (FFD)
ZigBee Coordinator (FFD)
Mesh Link
1. Star networks support a single ZigBee coordinator with one or more
ZigBee End Devices (up to 65,536 in theory)
2. Mesh network routing permits path formation from any source device
to any destination device
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Wireless Networking Basics
1. Network Scan
Device scans the 16 channels to determine the best channel to occupy.
2. Creating/Joining a PAN
Device can create a network (coordinator) on a free channel or join an existing
network
3. Device Discovery
Device queries the network to discover the identity of devices on active
channels
4. Service Discovery
Device scans for supported services on devices within the network
5. Binding
Devices communicate via command/control messaging
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Network Pieces – PAN Coordinator
1. PAN Coordinator
“owns” the network
1) Starts it
2) Allows other devices to join it
3) Provides binding and address‐table
services
4) Saves messages until they can be
delivered
5) And more… could also have i/o
capability
A “full‐function device” – FFD
Mains powered
PAN Coordinator
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Network Pieces ‐ Router
1. Routers
Routes messages
Does not own or start network
1) Scans to find a network to join
Given a block of addresses to assign
A “full‐function device” – FFD
Mains powered depending on topology
Could also have i/o capability Routers
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Network Pieces – End Device
1. End Device
Communicates with a single device
Does not own or start network
1) Scans to find a network to join
Can be an FFD or RFD (reduced function device)
Usually battery powered
End Device
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Battery Life
1. ZigBee protocol was designed from the ground up to support
very long life battery applications
2. Users can expect
Near‐shelf life in a typical monitoring application
3. Battery life is ultimately a function of
battery capacity and application usage
4. Many industrial applications are in harsh thermal environments
Batteries may include alkalines or Li‐primaries
Other forms of power generation might include solar, mechanical,
piezoelectric
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ZigBee Membership Classes
1. Promoters
founding members of ZigBee, who form the Board of Directors. There are
currently 5 promoters + 1 chairperson
2. Participants
members who generally wish to make technical contributions and/or serve
on the Technical Group committees. These members have early access to
specifications, and they may also chair working group subcommittees. They
are in a position to help shape the ZigBee technology for industrial
applications and the connected home.
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Participants
And more each month…
Promoters
ZigBee Alliance Member
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IEEE 802.15.4
IEEE 802.15 Working Group
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Comparison between WPAN
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IEEE 802.15.4 Basics (1/2)
1. Simple packet data protocol for lightweight wireless networks
Released in May 2003
Channel Access is via Carrier Sense Multiple Access with collision avoidance
and optional time slotting
Message acknowledgement and an optional beacon structure
Multi‐level security
Works well for
1) Long battery life, selectable latency for controllers, sensors, remote monitoring and
portable electronics
Configured for maximum battery life, has the potential to last as long as the
shelf life of most batteries
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2.40 2.41 2.482.472.462.452.442.432.42
2.4622.4372.412 2.4835 (end of ISM Band)
Possible 802.11 Channel (North America)802.11 Spectrum Occupancy (Typical)802.11 DSSS
Normal Channel Occupancy
IEEE 802.15.4 Basics (2/2)
868.3 MHz
902‐928 MHz
2405‐2480 MHz
Frequency Band License Required? Geographic Region Data Rate Channel Number (s)
No
No
Europe
Americas
WorldwideNo
20 kbps
40 kbps
250 kbps
0
1‐10
11‐26
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IEEE 802.15.4 Standard (1/2)
1. IEEE 802.15.4 standard released May 2003
Semiconductor manufacturers
1) Sampling Transceiver ICs and platform hardware/software to Alpha Customers now
Users of the technology
1) Defining application profiles for the first products, an effort organized by the ZigBee
Alliance
2. Includes layers up to and including Link Layer Control
LLC is standardized in 802.1
3. Supports multiple network topologies including Star, Cluster Tree and
Mesh
Introduction to The IEEE 802.15.4 Standard
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IEEE 802.15.4 Standard (2/2)
IEEE 802.15.4 MAC
IEEE 802.15.4 LLC IEEE 802.2
LLC, Type I
IEEE 802.15.4
2400 MHz PHY
IEEE 802.15.4
868/915 MHz PHY
Data Link Controller (DLC)
Networking App Layer (NWK)
ZigBee Application Framework1. Features of the MAC:
Association/dissociation
ACK
frame delivery
channel access mechanism
frame validation
guaranteed time slot management
beacon management
channel scan
Low complexity:
1) 26 primitives versus 131 primitives for 802.15.1 (Bluetooth)
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1. PHY functionalities:
Activation and deactivation of the radio transceiver
Energy detection within the current channel
Link quality indication for received packets
Clear channel assessment for CSMA‐CA
Channel frequency selection
Data transmission and reception
IEEE 802.15.4 PHY overview
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PreambleStart ofPacketDelimiter
PHY Header
PHY ServiceData Unit (PSDU)
4 Octets0‐127 Bytes
Sync Header PHY Payload
1 Octets 1 Octets
Frame Length(7 bit)
Reserve(1 bit)
1. PHY packet fields
Preamble (32 bits) – synchronization
Start of packet delimiter (8 bits) – shall be formatted as “11100101”
PHY header (8 bits) –PSDU length
PSDU (0 to 127 bytes) – data field
PHY frame structure
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868MHz/915MHz PHY
2.4 GHz
868.3 MHz
Channel 0 Channels 1‐10
Channels 11‐26
2.4835 GHz
928 MHz902 MHz
5 MHz
2 MHz
2.4 GHz PHY
Operating frequency bands
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1. The standard specifies two PHYs :
868 MHz/915 MHz direct sequence spread spectrum (DSSS) PHY (11 channels)
1) 1 channel (20Kb/s) in European 868MHz band
2) 10 channels (40Kb/s) in 915 (902‐928)MHz ISM band
2450 MHz direct sequence spread spectrum (DSSS) PHY (16 channels)
1) 16 channels (250Kb/s) in 2.4GHz band
Frequency bands and data rates
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IEEE 802.15.4 MAC
1. Employs 64‐bit IEEE & 16‐bit short addresses
Ultimate network size can be >> nodes (more than we’ll probably need…)
Using local addressing, simple networks of more than 65,000 (2^16) nodes
can be configured, with reduced address overhead
2. Three devices specified
Network Coordinator
Full Function Device (FFD)
Reduced Function Device (RFD)
3. Simple frame structure
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IEEE 802.15.4 MAC
1. Reliable delivery of data
2. Association/disassociation
3. AES‐128 security
4. CSMA‐CA channel access
5. Optional super frame structure with beacons
6. Optional GTS mechanism
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MAC/PHY Frame Format
MAC protocol data unit
MAC HeaderMAC service data unit MAC footer
Framecontrol
Sequence number
Addressinfo
PayloadFrame checksequence
PHY service data unit
PHY protocol data unit
LengthPreamble
Bytes: 2 1 0‐20 variable 2
MACsub layer
MAC frame
Four frame types:
1. Beacon
2. Data
3. MAC command
4. Acknowledge
Max 127 Bytes
Bytes: 4 1 Max 127 Bytes
SFD
1
IEEE 802.15 .4 MAC/PHY Frame Format
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1. A superframe is divided into two parts
Inactive: all devices sleep
Active:
1) Active period will be divided into 16 slots
2) 16 slots can further divided into two parts
Contention access period
Contention free period
0 10987654321 14131211 15
GTS 0
GTS 1
Beacon Beacon
CAP CFP
Inactive
SD = aBaseSuperframeDuration*2SO symbols (Active)
BI = aBaseSuperframeDuration*2BO symbols
Superframe (1/3)
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1. Beacons are used for
starting superframes
synchronizing with associated devices
announcing the existence of a PAN
informing pending data in coordinators
2. In a beacon enabled network,
Devices use the slotted CAMA/CA mechanism to contend for the usage of
channels
FFDs which require fixed rates of transmissions can ask for guarantee time slots
(GTS) from the coordinator
3. The structure of superframes is controlled by two parameters: beacon
order (BO) and superframe order (SO)
BO decides the length of a superframe
SO decides the length of the active potion in a superframe
Superframe (2/3)
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Superframe (3/3)
1. For a beacon‐enabled network, the setting of BO and SO should satisfy
the relationship 0≦SO≦BO≦14
2. For channels 11 to 26, the length of a superframe can range from 15.36
msec to 215.7 sec.
which means very low duty cycle
3. Each device will be active for 2‐(BO‐SO) portion of the time, and sleep for 1‐
2‐(BO‐SO) portion of the time
4. In IEEE 802.15.4, devices’ duty cycle follow the specification
< 0.10.1950.390.781.563.1256.25122550100Duty cycle
(%)
≧109876543210BO-SO
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1. Data transferred from device to coordinator
In a beacon‐enable network, device finds the beacon to synchronize to the
superframe structure. Then using slotted CSMA/CA to transmit its data.
In a non beacon‐enable network, device simply transmits its data using
unslotted CSMA/CA
Communication to a coordinatorIn a beacon‐enabled network
Communication to a coordinatorIn a non beacon‐enabled network
Data Transfer Model (Device to Coordinator)
Device to Coordinator
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1. Data transferred from
coordinator to device
In a beacon‐enable network, the
coordinator indicates in the
beacon that the data is pending.
Device periodically listens to the
beacon and transmits a MAC
command request using slotted
CSMA/CA if necessary.
Communication from a coordinatorIn a beacon‐enabled network
Data Transfer Model (Coordinator to Device )
Coordinator to Device (1/2)
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Communication from a coordinator in a non beacon‐enabled network
1. Data transferred from coordinator to
device
In a non‐beacon‐enable network, a
device transmits a MAC command
request using unslotted CSMA/CA. If
the coordinator has its pending data,
the coordinator transmits data frame
using unslotted CSMA/CA. Otherwise,
coordinator transmits a data frame
with zero length payload.
Data Transfer Model (Coordinator to Device )
Coordinator to Device (2/2)
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1. Two type channel access mechanism:
In non‐beacon‐enabled networks unslotted CSMA/CA channel access
mechanism
In beacon‐enabled networks slotted CSMA/CA channel access mechanism
Channel Access Mechanism
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1. In slotted CSMA/CA
The backoff period boundaries of every device in the PAN shall be aligned
with the superframe slot boundaries of the PAN coordinator
1) i.e. the start of first backoff period of each device is aligned with the start of the
beacon transmission
The MAC sublayer shall ensure that the PHY layer commences all of its
transmissions on the boundary of a backoff period
2. Each device shall maintain three variables for each transmission attempt
NB: number of time the CSMA/CA algorithm was required to backoff while
attempting the current transmission
CW: contention window length, the number of backoff periods that needs to
be clear of channel activity before transmission can commence (initial to 2 and
reset to 2 if sensed channel to be busy)
BE: the backoff exponent which is related to how many backoff periods a
device shall wait before attempting to assess a channel
CSMA/CA Algorithm
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IEEE 802.15.4 MAC Options
1. Two channel access mechanisms
Non‐beacon network
1) Standard ALOHA CSMA‐CA communications
2) Positive acknowledgement for successfully received packets
Beacon‐enabled network
1) Super frame structure
For dedicated bandwidth and low latency
Set up by network coordinator to transmit beacons at predetermined intervals
15ms to 252sec (15.38ms*2n where 0 ≤ n ≤ 14)
16 equal‐width time slots between beacons
Channel access in each time slot is contention free
Three security levels specified
1) None
2) Access control lists
3) Symmetric key employing AES‐128
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IEEE 802.15.4 Device Types
1. Three device types
Network Coordinator
1) Maintains overall network knowledge; most sophisticated of the three types; most
memory and computing power
Full Function Device
1) Carries full 802.15.4 functionality and all features specified by the standard
2) Additional memory, computing power make it ideal for a network router function
3) Could also be used in network edge devices (where the network touches the real
world)
Reduced Function Device
1) Carriers limited (as specified by the standard) functionality to control cost and
complexity
2) General usage will be in network edge devices
2. All of these devices can be no more complicated than the transceiver, a
simple 8‐bit MCU and a pair of AAA batteries!
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Data Frame Format
1. One of two most basic and important structures in 15.4
2. Provides up to 104 byte data payload capacity
3. Data sequence numbering to ensure that all packets are tracked
4. Robust frame structure improves reception in difficult conditions
5. Frame Check Sequence (FCS) ensures that packets received are without
error
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Acknowledgement Frame Format
1. The other most important structure for 15.4
2. Provides active feedback from receiver to sender that packet was received
without error
3. Short packet that takes advantage of standards‐specified “quiet time”
immediately after data packet transmission
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MAC Command Frame Format
1. Mechanism for remote control/configuration of client nodes
2. Allows a centralized network manager to configure individual clients
no matter how large the network
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1. Beacons add a new level of functionality to a network
2. Client devices can wake up only when a beacon is to be broadcast, listen
for their address, and if not heard, return to sleep
3. Beacons are important for mesh and cluster tree networks to keep all of the
nodes synchronized without requiring nodes to consume precious battery
energy listening for long periods of time
Beacon Frame Format
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Frequencies and Data Rates
1. The two PHY bands (UHF/Microwave) have different physical,
protocol‐based and geopolitical characteristics
Worldwide coverage available at 2.4GHz at 250kbps
900MHz for Americas and some of the Pacific
868MHz for European‐specific markets
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ISM Band Interference and Coexistence
1. Potential for interference exists in every ISM band, not just 2.4GHz
2. IEEE 802.11 and 802.15.2 committees are addressing coexistence issues
3. ZigBee/802.15.4 Protocol is very robust
Clear channel checking before transmission
Backoff and retry if no acknowledgement received
Duty cycle of a ZigBee‐compliant device is usually extremely low
It’s the “cockroach that survives the nuclear war”
1) Waits for an opening in otherwise busy RF spectrum
2) Waits for acknowledgements to verify packet reception at other end
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IEEE 1451.5 Sensor Group
1. A survey was conducted mid‐2002 on the characteristics of a wireless
sensor network most important to its users
2. In order of importance, these characteristics are
Data Reliability
Battery Life
Cost
Transmission Range
Data Rate
Data Latency
Physical Size
Data Security
3. How would you modify these requirements, if at all?
IEEE 1451.5 Sensor Group Wireless Criteria
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Freescale 802.15.14 Radio Example
1. Key Features
IEEE® 802.15.4 Compliant
1) 2.4GHz
2) 16 selectable channels
3) 250Kbps Data Rate
4) 250Kbps 0‐QPSK DSSS
Multiple Power Saving Modes
1) Hibernate 2.3uA
2) Doze 35uA
3) Idle 500uA
RF Data Modem
Up to 7 GPIO
SPI Interface to Micro
PowerManagement
MC13191/2/3
Analog Receiver
Internal Clock
Generator
8-ch 10-BitADC
BDMHCS08 CPU
2xSCI
4-ch 16-bitTimer
FlashMemory
RAM
COP
IIC
Up to36 GPIO
SPI
LVI
MC9S08GT Family
Sensors
MMA Series Accelerometers
MPX Series Pressure Sensors
MC Series Ion and
Smoke PhotoSensors
Voltage Regulators
FrequencyGenerator
AnalogTransmitter
Dig
ital
Tra
ns
ce
ive
r GPIO
SPI
Timers
IRQ Arbiter
RAM Arbiter
Buffer RAM
ControlLogic
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Freescale 802.15.14 Radio Example
cont’d
Internal Timer comparators (reduce MCU resources)
‐16.6dBm to +3.6dBm output power
1) Software selectable
2) On‐chip regulator
Up to ‐92 Rx sensitivity at 1% PER
2V to 3.4 operating voltage
‐40˚C to +85˚C operating temperature
Low external component count
1) Requires single 16Mhz Xtal (Auto Trim)
5mmx5mm QFN‐32
1) Lead‐Free
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IEEE 802.15.4
ZigBee StackIEEE 802.15.4 MACSimple MAC (SMAC)Software
Integrated on‐chipTx/Rx Switch
$3.28$2.75$2.3510K SRP
5x5x1 mm 32‐pin QFN (Meets RoHS requirements)Package
Packet and StreamingPacketTransfer Mode
Peer‐to‐Peer, Star and MeshPoint‐to‐Point and StarNetwork Topology
250 Kbps, O‐QPSK Modulation, DSSS Energy Spreading SchemeThroughput
‐40º to +85ºC Operating TemperatureOperating Temp
Programmable clock output available to MCU
Buffered transmit and receive data packets for use with low cost MCUs
Low component count reduces complexity and cost
‐27 dBm to +4 dBm (software selectable)Power Output
SPI Interface to MCUMCU Interface
Optimized for 8‐bit HCS08 Family8‐bit MCU, ColdFire, S12, DSCMCU Support
2.0 to 3.4 VPower Supply
‐94 dBm‐91 dBmSensitivity
Off, Hibernate, Doze and IdleLow Power Modes
ZigBee‐Ready 2.4 GHz transceiverIEEE 802.15.4 Compliant 2.4 GHz
transceiver
Low cost 2.4 GHz transceiver for
proprietary applicationsOverview
MC13203MC13202MC13201
Robot Sensor Networks
HanyangUniversity
Robot Sensor Networks
HanyangUniversity
The 802.15.4 / Zigbee Sandbox
Range
Pea
k D
ata
Rat
e
Closer Farther
Slo
wer
Fas
ter
UWB
HomeRF
Wireless Data Applications
Wireless Video Applications
IrDA
802.11g
802.11b
802.11a
2.5G/3G
ZigBee
802.15.4
Bluetooth
ISM Link
WiFi
Robot Sensor Networks
HanyangUniversity
The Application Space
BUILDING AUTOMATION
Security, HVAC,AMR,
Lighting Control, Access Control
CONSUMER ELECTRONICS
Remote Control
PERSONAL HEALTH CARE
Patient monitoring
INDUSTRIALCONTROL
Asset Mgt, Process Control,
Energy Mgt
RESIDENTIAL/LIGHT COMMERCIAL
CONTROL
Security, HVAC,Lighting Control,Access Control
PC & PERIPHERALS
Mouse, Keyboard,Joystick
The Application Space for 802.15.4/ZigBee
Robot Sensor Networks
HanyangUniversity
The Wireless Market
PAN
< RANGE
> LAN
LOW < DATA RATE > HIGH
TEXT GRAPHICS INTERNET HI‐FI AUDIO
STREAMINGVIDEO
DIGITALVIDEO
MULTI‐CHANNELVIDEO
Bluetooth1
Bluetooth 2
ZigBee
802.11b
802.11a/HL2 & 802.11g
Robot Sensor Networks
HanyangUniversity
Market Size
1. Strong growth in areas such as wireless sensors will help fuel the
growth of 802.15.4 and ZigBee
Harbor Research reports that by 2008, 100 million wireless sensors will be in
use
On World reports that by 2010, more then 500 million nodes will ship for wireless
sensor applications
2. ABI Research forecasts shipments of ZigBee devices in 2005 at about 1
million, growing to 80 million units by the end of 2006
3. In‐Stat 2004 report has an aggressive forecast of over 150 million annual
units of 802.15.4 and ZigBee chipsets by 2008
802.15.4/ZigBee Market Size
Robot Sensor Networks
HanyangUniversity
Features of Protocol Stack
1. ZigBee Alliance
50+ companies: semiconductor mfrs, IP providers, OEMs, etc.
Defining upper layers of protocol stack: from network to application, including
application profiles
First profiles published mid 2003
2. IEEE 802.15.4 Working Group
Defining lower layers of protocol stack: MAC and PHY scheduled for release in April
SILICON
ZIGBEE STACK
APPLICATION Customer
IEEE802.15.4
ZigBee Alliance
Development of the Standard
Robot Sensor Networks
HanyangUniversity
Frequencies and Data Rates
868 MHz
915 MHz
BAND COVERAGE DATA RATE # OF CHANNEL(S)
Europe 20 kbps 1
2.4 GHz ISM Worldwide 250 kbps 16
ISM Americas 40 kbps 10
Robot Sensor Networks
HanyangUniversity
Stack Reference Model (1/2)
IEEE 802.15.4 PHY
IEEE 802.15.4 MAC (CPS)
ZigBee NWK
MAC (SSCS)802.2 LLC
IP
API UDP
ZA1 ZA2 … ZAn IA1 IAn
Transmission & reception on the physical radio channel
Channel access, PAN maintenance, reliable data transport
Topology management, MAC management, routing, discovery protocol,
security management
Application interface designed Using general profile
End developer applications, designed using application profiles
Robot Sensor Networks
HanyangUniversity
Stack Reference Model (2/2)
1. Microcontroller utilized
2. Full protocol stack <32 k
3. Simple node-only stack ~4k
4. Coordinators require extra RAM
Node device database
Transaction table
Pairing table
PHY LAYER2.4 GHz 915MHz 868 MHz
MAC LAYERMAC LAYER
NETWORK LAYERStar/Cluster/Mesh
APPLICATION INTERFACE
APPLICATIONS
SiliconApplication ZigBee Stack
Customer
IEEE802.15.4
ZigBee Alliance
SECURITY
Robot Sensor Networks
HanyangUniversity
ZigBee and Bluetooth
ZigBee
Smaller packets over large
network
Mostly Static networks with
many, infrequently used devices
Home automation, toys, remote
controls, etc.
Bluetooth
Larger packets over small network
Ad‐hoc networks
File transfer
Screen graphics, pictures, hands‐
free audio, Mobile phones,
headsets, PDAs, etc.
Optimized for different applications
Robot Sensor Networks
HanyangUniversity
Address Different Needs
1. Bluetooth is a cable replacement for items
like Phones, Laptop Computers, Headsets
2. Bluetooth expects regular charging
Target is to use <10% of host power
3. ZigBee is better for devices Where the
battery is ‘rarely’ replaced
Targets are :
1) Tiny fraction of host power
2) New opportunities where wireless not yet
used
Robot Sensor Networks
HanyangUniversity
ZigBee
1. DSSS‐ 11 chips/ symbol
2. 62.5 K symbols/s
3. 4 Bits/ symbol
4. Peak Information Rate
~128 Kbit/second
Bluetooth
1. FHSS
2. 1 M Symbol / second
3. Peak Information Rate
~720 Kbit / second
Air Interface
Robot Sensor Networks
HanyangUniversity
Silicon
PHY Layer
MAC LayerMAC Layer
Data Link Layer
Network Layer
ZigBeeStack
Application
Application Interface
Application
Zigbee
Silicon
RF
Baseband
Link Controller
Vo
ice
Link Manager
Host Control Interface
L2CAP
TelephonyControlProtocol
Inte
rco
m
Hea
dse
t
Co
rdle
ss
Gro
up
Cal
l
RFCOMM(Serial Port)
OBEX
BluetoothStack
Applications
vCar
d
vCal
vNo
te
vMes
sag
e
Dia
l-u
pN
etw
ork
ing
Fax ServiceDiscoveryProtocol
User Interface
Bluetooth
Protocol Stack Comparison
Robot Sensor Networks
HanyangUniversity
Bluetooth:Network join time = >3s
Sleeping slave changing to active = 3s typically
Active slave channel access time = 2ms typically
ZigBee:Network join time = 30ms typically
Sleeping slave changing to active = 15ms typically
Active slave channel access time = 15ms typically
ZigBee protocol is optimized for timing critical applications
Timing Considerations
Robot Sensor Networks
HanyangUniversity
Comparison Overview
Bluetooth ZigBee
AIR INTERFACE FHSS DSSS
PROTOCOL STACK 250 kb 28 kb
BATTERY rechargeable non‐rechargeable
DEVICES/NETWORK 8 255
LINK RATE 1 Mbps 250 kbps
RANGE ~10 meters (w/o pa) ~30 meters
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (1/8)
1. Consistently perform a given task to the desired result despite all
changes of environmental behavior
2. Without fail
3. A necessary ingredient of trust
4. “When the sensor measures its environment; the controller always
knows that same value”
5. The wireless medium is not a protected environment like the wired
medium, but rather, it is fraught with degradations, disruptions, and
pitfalls such as dispersion, multipath, interference, frequency dependent
fading, sleeping nodes, hidden nodes, and security issues.
Robot Sensor Networks
HanyangUniversity
1. Each of these degradations and disruptions can be mitigated by various
mechanisms within the ISO layers; but not all mechanisms are compatible
with all other mechanisms or may negatively impact critical performance
attributes
2. The system must be optimized for the best performance in a realistic
environment
3. In addition to the previous disruptions there is the case of sending
messages to devices that are not receiving, e.g. they’re in the “sleep” mode.
When this happens the message needs to be buffered by another device
that is able to send the message when the sleeping device wakes up.
Reliability Throughout the Stacks (2/8)
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (3/8)
Router
X X
Hidden Node
Interferer
Multipath
Sleeping Node NetworkCoordinator
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (4/8)
1. IEEE 802.15.4 has built upon the successes of previous IEEE 802
standards by selecting those mechanisms proven to ensure good
reliability without seriously degrading system and device performance.
ISO Layers:
1. PHY: Direct Sequence with Frequency Agility (DS/FA)
2. MAC: ARQ, Coordinator buffering
3. Network: Mesh Network (redundant routing)
4. Application Support Layer: Security
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (5/8)
PHY Layers:
1. Direct sequence: allows the radio to reject multipath and interference by
use of a special “chip” sequence. The more chips per symbol, the higher
its ability to reject multipath and interference.
2. Frequency Agility: ability to change frequencies to avoid interference
from a known interferer or other signal source.
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (6/8)
MAC:
1. ARQ (acknowledgement request) is where a successful transmission is
verified by replying with an acknowledge (ACK). If the ACK is not
received the transmission is sent again
2. Coordinator buffering is where the network coordinator buffers
messages for sleeping nodes until they wake again
Network:
1. Mesh Networking: allows various paths of routing data to the
destination device. In this way if a device in the primary route is not able
to pass the data, a different valid route is formed, transparent to the user.
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (7/8)
Application Support Sub‐layer(APS):
1. Security: supports reliability by keeping other devices from corrupting
communications.
2. The APS configures the security emplaced in the MAC layer and also
adds some of its own.
Robot Sensor Networks
HanyangUniversity
Reliability Throughout the Stacks (8/8)
ZigBee End Device (RFD or FFD)
ZigBee Router (FFD)
ZigBee Coordinator (FFD)
Mesh Link
Star Link
Reliability: Mesh Networking
Robot Sensor Networks
HanyangUniversity
IEEE 802 Direct Sequence
1. As can be seen from above, IEEE802.15.4/ZigBee has more processing
gain (chips/symbol) than its predecessors
32151111Chips/Symbol
15.4(2.4)
15.4(900)
11b11IEEE 802.
Robot Sensor Networks
HanyangUniversity
Direct Sequence and Frequency Agility
2.4 GHz
Channels 11‐26
2.4835 GHz
5 MHz2.4 GHz PHY
Over the Air After DS correlation
Interferer Desired Signal
Robot Sensor Networks
HanyangUniversity
Robustness Throughout the Stacks (1/4)
1. Let’s define robustness as the ability to tolerate significant degrading
phenomena in the physical medium
2. Multipath and interference are probably the most significant
degradations to the channel model.
Robustness of IEEE 802.15.4 and ZigBee
Robot Sensor Networks
HanyangUniversity
Robustness Throughout the Stacks (2/4)
1. Frequency hopping is a method that allows the radio to periodically
change channels to over time minimize the effect of a “bad” channel.
While this technique is very effective in some circumstances it creates
other problems such as latency, network uncertainty for sleeping nodes,
loss of the product bandwidth x time, etc.
2. Direct Sequence with Frequency Agility (DS/FA) combines the best
features of DS and FH without most of the problems caused by frequency
hopping because frequency changes aren’t necessary most of the time,
rather they’re appropriate only on an exception basis.
Robot Sensor Networks
HanyangUniversity
Robustness Throughout the Stacks (3/4)
1. The 802.11 Working Group couldn’t agree upon which of the following
PHYs was the best: FH, IR, or DS. So all three were standardized and left
to the market to decide.
2. Of the three PHYs; DS was the clear market winner. DS provided
sufficient robustness with higher overall performance.
3. Excess robustness does not achieve higher performance, rather it
typically costs performance
Robot Sensor Networks
HanyangUniversity
Robustness Throughout the Stacks (4/4)
1. IEEE 802.15.4/ZigBee have addressed reliability throughout the ISO stack
with proven mechanisms to minimize the uncertainty of the wireless
medium
Reliability and Robustness throughout the stacks of IEEE
802.15.4 and ZigBee
Robot Sensor Networks
HanyangUniversity
802.15.4/ZigBee vs Bluetooth
1. Bluetooth and 802.15.4 transceiver physical characteristics are very
similar
2. Protocols are substantially different and designed for different purposes
3. 802.15.4 designed for low to very low duty cycle static and dynamic
environments with many active nodes
4. Bluetooth designed for high QoS, variety of duty cycles, moderate data
rates in fairly static simple networks with limited active nodes
5. Bluetooth costs and system performance are in line with 3rd and 4th
generation products hitting market while 1st generation 15.4 products
will be appearing only late this year
Robot Sensor Networks
HanyangUniversity
Transceiver Comparisons
1. Instantaneous Power Consumption
15.4 Transceivers are “similar” to Bluetooth Transceivers1) 802.15.4
OQPSK with shaping
Max data rate 250kbps over the air
2Mchips/s over the air Direct Sequence Spread Spectrum (62.5ksps*32 spread)
‐90 dBm sensitivity
40ppm xtal
2) Bluetooth
FSK
Max data rate 720kbps over the air
1Msps over the air Frequency Hop Spread Spectrum (79 channels @ 1600 hps)
‐85dBm sensitivity
20ppm xtal
2. Instantaneous power consumption will be similar for the raw
transceivers without protocol
3. Bluetooth’s frequency hop makes it extremely difficult to create
extended networks without large synchronization cost
Robot Sensor Networks
HanyangUniversity
General Schematic
802.15.4XCVR
MCU
32.768kHz
IRQ
SPI SPI
16.000MHz
VccVcc
INTIRQ/
4
OSC1 OSC2
3Vdc
RESET
HeartbeatSensor
Plus about 10‐12 small value capacitors, resistors
excluding any special components for heartbeat sensor)
Robot Sensor Networks
HanyangUniversity
802.15.4/ZigBee Operation Mode
1. 802.15.4/ZigBee ModeNetwork environment using Guaranteed Time Slot (GTS)
Network beacons occurring either every1) 960ms or 61.44s (closest values to 1 and 60 s)
2) Guaranteed time slot occurs at some predetermined point in the beacon interval
2. Sensor has two ongoing processesHeartbeat time logging
Transmit heartrate and other information (8 bytes total)1) Instantaneous heartrate (1/timeinterval between last two pulses,1ms precision)
2) Running average heartrate (1/time interval between last twenty pulses, 1ms precision)
3) Sensor average temperature (0.1C precision)
4) Sensor average battery state (0.1V precision)
time
heartbeat
GTS
Beacon
Robot Sensor Networks
HanyangUniversity
Protocol Makes the Difference
1. 15.4 Protocol was developed for very different reasons than Bluetooth
802.15.4
1) Very low duty cycle, very long primary battery life applications
2) Static and dynamic star and mesh network structures with potentially a very large number (>>65534) of client units, low latency available but not necessary
3) Ability to remain quiescent for long periods of time without communicating to the network
Bluetooth
1) Moderate duty cycle, secondary battery operation where battery lasts about the same as master unit
2) Wire replacement for consumer devices that need moderate data rates with very high QoS and very low, guaranteed latency
3) Quasi‐static star network structure with up to 7 clients (and ability to participate in more than one network simultaneously)
4) Generally used in applications where either power is cycled (headsets, cellphones) or mains‐powered (printers, car kits)
2. Protocol differences can lead to tremendous optimizations in power consumption
Robot Sensor Networks
HanyangUniversity
Applications
1. Industrial Control/Monitoring Space
Asset Management
1) Basic identification
Device ID, Device PN/SN, Device source/destination, etc.
2) Asset “health”Temperature, humidity, shock, fuel levels, etc.
Nearly any parameter can be monitored given an appropriate sensor
Asset Tracking
1) Location tracking through two‐way communication
Simplest form is communication/identification when passes a checkpoint
Same as other RFID tagging systems
More sophisticated “what other devices can it hear/communicate with?”
Other options include ranging (time of flight) and SNR measurement
Has the potential for very precise location measurement
The wireless network uses protocol gateways to move command/monitor
data between the end devices and the network data management center
Robot Sensor Networks
HanyangUniversity
HVAC
Field Service or mobile worker
ServiceProvider
Retailer
Corp Office
Mfg Flow
Temp. Sensor
Security Sensor
DatabaseGateway
Telephone Cable line
Back EndServer
Materials handling
Warehouses, Fleet management, Factory, Supermarkets,
Office complexes
Gas/Water/Electric meter, HVAC
Smoke, CO, H2O detector
Refrigeration case or appliance
Equipment management services & PM
Security services
Lighting control
Assembly line and work flow, Inventory
Materials processing systems (heat, gas flow, cooling,
chemical)
Energy, diagnostics, e‐Business services
Gateway or Field Service links to sensors &
equipment
Monitored to suggest PM, product updates, status
changes
Nodes link to PC for database storage
PC Modem calls retailer, Service Provider, or Corp
headquarters
Corp headquarters remotely monitors assets, billing,
energy management
Product Examples
Robot Sensor Networks
HanyangUniversity
Data CommunicationTwo way
Dealer
Server
Field Service
Retailer SOHO
Telephone Cable line
ServiceProvider
AC or heat Pump
Gateway(s)
Temp. Sensor
Body monitor
Security Sensor
PC & peripherals Entertainment
Back EndServer
Customers
White goods
1. Mobile clients link to PC for database storage
PC links to peripherals, interactive toys
PC Modem calls retailer, SOHO, Service Provider
2. Gateway links to security system, temperature sensor, AC system, entertainment, health.
3. Gateway links to field sales/service
Home & Diagnostics Examples
Robot Sensor Networks
HanyangUniversity
Motorola 802.15.4/ZigBee™ Platform
Motorola RF Packet Radio Motorola 8‐Bit MCU
System Simplicity and Flexibility
Robot Sensor Networks
HanyangUniversity
Motorola 802.15.4 / ZigBee™ Solution
1. Features
2.4 GHz Band, ‐90 dBm RX sensitivity at 1% PER
1) IEEE spec is –85 dBm
Power supply 2.0‐3.6 V w/ on‐chip regulator, logic interface 1.7 to 3.3
1) Runs off a single Li or 2 alkaline cells
Complete RF transceiver data modem – antenna in, fully packetized data out
Data and control interface via standard SPI at 4 to 8 MHz
802.15.4 MAC
A large number of Motorola’s substantial line of HC08 MCUs will
interoperate with the data modem chip
1) Often 802.15.4 functionality can be added to existing systems simply by including
the modem chip and reprogramming an existing MCU that may already be in the
application
HC08 RAM/FLASH configurations from 384B/4kB to 2kB/60kB depending
upon application SW needs
Robot Sensor Networks
HanyangUniversity
1. Designed for the IEEE 802.15.4 and ZigBee™ standards
Operates in the 2.4 GHz ISM band available worldwide
Cost effective CMOS design
Low external components, no T/R switch required
On‐chip low noise amplifier
0dBm (1.0 mW) PA, step adjustable to –30dBm
Integrated VCO, no external components
Full spread‐spectrum encoding and decoding compatible with 802.15.4
RX sensitivity of –90 dBm at 1% PER, better than specification
Engineered to support 250 kBit/s O‐QPSK data in 5.0 MHz channels, per the
IEEE 802.15.4 specification
No line‐of‐sight limitations as with infrared (IR)
RF Data Modem Transceiver (1/2)
Robot Sensor Networks
HanyangUniversity
1. Designed to run DIRECTLY off two alkaline AA or AAA cells, or one
Lithium cell
2.0 to 3.6 V with on‐chip voltage regulator
Can use the full capacity of the battery (to end of life ~1.0V per cell)
2. Buffered transmit and receive data packets for simplified use with low‐
end microcontrollers
3. SPI data and control interface, operates up to 8MHz
4. Designed to support peer to peer and star topologies
5. On‐board timers to support optional Superframe/Guaranteed Time Slots
for low latency transfer
6. Will support optional Zigbee™ Network layer software
7. Application‐configurable power‐saving modes that take best advantage
of battery operation
RX/TX > Idle > Doze > Hibernate > Off
RF Data Modem Transceiver (2/2)
Robot Sensor Networks
HanyangUniversity
12kB FLASH 8‐BitMicrocontroller
Application
RF Transmitter
RF Receiver DigitalProcessing
RF Transceiver ICSPI
32kB FLASH 8‐BitMicrocontroller
Application
Application‐specific interfaces
RF Transmitter
RF Receiver DigitalProcessing
RF Transceiver ICSPI
3kB FLASH (min) 8‐BitMicrocontroller
Application
RF Transmitter
RF Receiver DigitalProcessing
RF Transceiver ICSPI
Direct SPI Calls
802.15.4 PHY Compliant Transceiver
System Complexity and Cost
15.4 RFD MAC
15.4 RFD MAC
>32kB FLASH 8‐BitMicrocontroller
Application
RF Transmitter
RF Receiver DigitalProcessing
RF Transceiver ICSPI
15.4 FFD MAC
Zigbee NWK
Zigbee NWK
802.15.4 is a guest in existing microcontrollers
Scalability to Address Specific Needs
Robot Sensor Networks
HanyangUniversity
1. Total System Solution
Single source for platform solution
1) Integrated Circuits, Reference Designs, Modules, Stack Software, Development Systems
2. Key technology enhancements provide for a superior solution
Adjacent channel rejection
1) Improvements in noisy environment
High Sensitivity Radio Solution
1) 5 dBm beyond spec – longer range
Extended Temperature Operating Range
1) ‐40°C to +85°C for industrial and automotive applications
Operating voltage range optimized for alkaline or lithium primary cells
1) 2.0 Vdc to 3.6 Vdc, disposable
Adjustable TX Output power
1) Improved coexistence for short range applications, improved battery life
3. IEEE and ZigBee™ Alliance membership
Technology and standards driver
Early access to new technology
Advantages
Robot Sensor Networks
HanyangUniversity
An Application Example (1/7)
1. Scenario Parameters
Battery‐operated keyboard
1) Part of a device group including a mouse or trackball, sketchpad, other human
input devices
2) Each device has a unique ID
3) Device set includes a USB to wireless interface dongle
Dongle powered continuously from computer
4) Keyboard does not have ON/OFF switch
5) Power modes
Keyboard normally in lowest power mode
Upon first keystroke, wakes up and stays in a “more aware” state until 5 seconds of inactivity have passes, then transitions back to lowest power mode
Wireless Keyboard
Robot Sensor Networks
HanyangUniversity
1. Typing Rates
10, 25, 50, 75 and 100 words per minute
2. Typing Pattern
Theoretical: Type continuously until battery is depleted
1) Measures total number of hours based upon available battery energy
Keyboard Usage
An Application Example (2/7)
Robot Sensor Networks
HanyangUniversity
1. 802.15.4 Operation Parameters
Star network
Non‐beacon mode (CSMA‐CA)
USB Dongle is a PAN Coordinator Full Functional Device (FFD)
Keyboard is a Reduced Function Device (RFD)
Power Modes
1) Quiescent Mode used for lowest power state
First keystroke latency is approx 25ms
2) Idle mode used for “more aware” stateKeystroke latency 8‐12 ms latency
Wireless Keyboard Using 802.15.4
An Application Example (3/7)
Robot Sensor Networks
HanyangUniversity
1. 802.15.4 Chipset Parameters
1) Motorola 802.15.4 Transceiver and HCS08 MCU
2) Battery operating voltage 2.0 – 3.6 V
All required regulation internal to ICs
Nearly all available energy usable with end of life voltage at 2.0 volts
Wireless Keyboard Using 802.15.4
An Application Example (4/7)
Robot Sensor Networks
HanyangUniversity
1. Bluetooth Operation Parameters
Piconet network
USB Dongle is piconet Master
Keyboard is a piconet Slave
Power Modes
1) Park mode used for lowest power state
1.28 second park interval
First keystroke latency is 1.28s
2) Sniff mode used for “more aware” state
15ms sniff interval
15ms latency
Wireless Keyboard Using Bluetooth
An Application Example (5/7)
Robot Sensor Networks
HanyangUniversity
1. Bluetooth Chipset Parameters
CSR BlueCore 2 –External + Flash + Regulator
Battery Operating Voltage 2.7 – 3.6 Vdc
1) Requires external regulator for best performance
2) Only 19 to 30 percent of available battery life usable with 2.7V cutoff voltage
Power Consumption (estimated)
1) Park Mode @ 1.28 s interval: 0.05mA avg
2) Sniff Mode @ 15ms interval: 8mA avg
3) NOTE: I do not assume a deep sleep mode since wake up time of 4 to 30 seconds
seems unacceptable
Wireless Keyboard Using Bluetooth
An Application Example (6/7)
Robot Sensor Networks
HanyangUniversity
BT: Approximately 5 operating days
802.15.4: Approx 38 days
Bad Hunt n’Peck
By the way, WirelessUSB looks
much like BT
Bluetooth vs. 15.4 Keyboard Comparison
An Application Example (7/7)
Robot Sensor Networks
HanyangUniversity
Q & A
1. 경청해주셔서감사합니다.
2. Q & A