Radiocrafts WP003 Selecting an IEEE 802.15.4, 2.4 GHz wireless solution

Radiocrafts  WP003 Selecting an IEEE 802.15.4, 2.4 GHz wireless solution
Radiocrafts
Embedded Wireless Solutions
WP003
Selecting an IEEE 802.15.4, 2.4 GHz wireless solution
By Ø.Nottveit
Abstract
Companies searching for a low power 2.45 GHz wireless solution will find many
different technical solutions. This white paper takes the reader thru the different
solutions offered by Radiocrafts, highlights the advantages of each and guides the
users to the technology solution best suited for them.
Introduction
When selecting a wireless technology as a solution for a given task, it is important to find the
right tool for the task in hand. All solutions have their strengths and their drawbacks, so it is
important to find the actual requirements to the wireless solution. Some of the requirements
differentiating the Radiocrafts solutions are:
•
•
Technical requirements
o Ease of use
o Coverage/mesh requirement
o Interoperability
o Integration with IP based networks
Business requirements
o Time to market
o Development cost
Other requirements such as low cost, small size and low power consumption are not taken
into account here since all Radiocrafts solutions satisfy this. But this could be important
factors when comparing to other technologies like WLAN/Bluetooth etc.
Figure 1. Radiocrafts’ solutions at 2.4GHz
©2008 Radiocrafts AS
White Paper WP003 (rev. 1.0)
Page 1 of 5
Radiocrafts
Embedded Wireless Solutions
WP003
RC232
The RC232 is a simple solution with the shortest time to market. By using RC232 modules
one can transfer serial port data from one module to another module (point to point) or
several other modules (point to multipoint). This technology does not include a routing mesh
technology and therefore the network is limited to a star topology. The communication is not
compatible with IEEE 802.15.4 and not treated in depth here. Please read more about our
RC232 solution on our website (www.radiocrafts.com).
Central node
Node
Star
What is IEEE 802.15.4 and what is the ZigBee® protocol?
The IEEE 802.15.4 is a wireless standard for the physical communication layer (PHY) and
media access (MAC) layer. The physical layer includes specification on frequencies,
modulation, date rate etc. The 802.15.4 specifies 1 channel at 868 MHz, 10 channels at 915
MHz and 16 channels at 2.4 GHz, but only the 2.4 GHz channels are widely used and are
treated in this document.
The MAC layer includes access method which is a combination of time division multiple
access (TDMA) and carrier sense multiple access with collision detect (CSMA-CD). The MAC
specification also includes a point to point acknowledgement and encryption.
The ZigBee Alliance adopted the IEEE 802.15.4 standard as their physical and MAC layer
and built the ZigBee protocol standard on top of that. The ZigBee standard includes the
network layer (NWK) as well as the application layer (APL). The network layer includes the
routing which enables mesh networks. Somewhat simplified it can be said that IEEE 802.15.4
provide a point-to-point link specification, while ZigBee specified how to communicate in a
network with multi-hops which is self-configuring and self-healing.
Applicaion layer (APL)
ZigBee standard
Network Layer (NWK)
Medium Access Control
(MAC)
IEEE 802.15.4 standard
Physical layer (PHY)
Figure 2. IEEE 802.15.4 and ZigBee protocol stack
©2008 Radiocrafts AS
White Paper WP003 (rev. 1.0)
Page 2 of 5
Radiocrafts
Embedded Wireless Solutions
WP003
802.15.4
There are a number of solutions available that is built on the IEEE 802.15.4 standard,
including ZigBee and 6LoWPAN (IPv6 over Low Power Personal Area Network) . One
alternative way for you to build a wireless network is to build your own proprietary standard on
top of the popular IEEE 802.15.4 layers. The IEEE 802.15.4 PHY / MAC protocol stack is free
to download for the RC220x and the RC230x modules. For more details on how to implement
an IEEE 802.15.4 solution on RC220x and RC230x please see reference [1].
ZigBee®
ZigBee is the leading worldwide standard for low power wireless network targeting
applications like Home Automation (HA), Advanced Metering Infrastructure (AMI), Building
automation (BA) and Wireless Sensor Networks (WSN). It is a mesh network consisting of a
Coordinator, Routers and End Devices. The mesh network enables a robust, self-configuring,
self-healing network. End Devices can be in power saving sleep mode most of the time and
hence be battery operated.
All the above mentioned applications are what are called profiles within ZigBee. A profile is a
specification on the application level of how the device shall operate. That means the profile
specifies what device parameters exists and what functions call the device supports. For
example, the HA profile specify a dimmer light that has brightness and on/off as parameters
and functions for turning light on/off and brightness control. It is important to include this
standardization at the application level in order to achieve interoperability between devices
from different vendors.
There are two ways of implementing a ZigBee solution with Radiocrafts modules. One is to
download a free ZigBee stack and then write the application code, compile and load the FW
onto a module. The second is to use a ZigBee module that acts as a ZigBee modem with a
serial API-command interface.
Both the RC2300 and the RC2200 platforms can be used for making ZigBee application. The
RC2200 is the first generation module with an AVR microcontroller from Atmel combined with
the industry leading CC2420 chip from TI/Chipcon. The RC2200 also comes in a high power
version, RC2201HP, with up to 17 dBm output. Because of the high output power this module
has en increased range, up to 750 meter line-of-sight with chip-antenna and 1500 meter with
external antenna. The RC2300 is the second generation module based on the CC2430 SoC
from TI/Chipcon. This is a very small and cost-competitive solution for ZigBee. For more
details on how to proceed to develop solutions on RC2200 and RC2300, please see
Application Note 3 [1].
To be able to call a product ZigBee compliant, it has to undergo a ZigBee qualification.
Read more on how to certify your product in [1].
ZNM - a ZigBee Network Module
A ZigBee protocol stack is a complicated piece of firmware if you try to understand all of it.
With numerous compiler directives, a large number of c-files interacting between each other
and 600 pages of documentation it will be a time-consuming task to understand everything.
This is why Radiocrafts offers the ZNM-module. This module includes the complete ZigBee
stack and gives the user access to this stack thru a serial API interface. By using this module
the user can control the ZigBee functionality through a small number of API commands. The
user still has to understand ZigBee basics, like network creation, binding, joining etc, but he
can now develop his application on an MCU of his own choice with a compiler of his own
choice. All these factors will enable an easier and faster ZigBee development.
©2008 Radiocrafts AS
White Paper WP003 (rev. 1.0)
Page 3 of 5
Radiocrafts
Embedded Wireless Solutions
WP003
6LoWPAN
6LoWPAN is formally known as RFC 4944 and is a standard put forth by the Internet
Engineering Task Force (IEFT), the same people that gave us the Internet standards. They
saw the need for a standard for transmitting IP packages over low power wireless networks.
Hence the name 6LoWPAN; IPv6 over Low Power Wireless Personal Area Network. As the
lower level protocol (PHY and MAC), the IETF chose the already established IEEE 802.15.4
standard. So their job simply became how to adapt IP to IEEE 802.15.4. The great advantage
of using this standard is that the IP packages used in the wired world could also be routed to
a sensor over a low power wireless link.
This simplifies the otherwise difficult task of integrating a wireless sensor network with an
established IP network. For more information on Radiocrafts’ 6LoWPAN solution, please
contact us (contact information at the end of this paper).
WLAN, Bluetooth etc.
Many customers ask if they can use WLAN and Bluetooth. Both are excellent technologies,
but it's always about matching the tool to the task in hand.
WLAN is excellent for PC to PC communication over short (0-100 meter) ranges. It has high
throughput and is plug-and-play with today's computers. But the power consumption is high
and with limited range and no mesh capabilities it is best at larger mains powered devices like
computers.
Bluetooth is also a very good technology, but have limited range (0-10 meter) and a bit to high
power consumption for battery powered devices (you have to charge a Bluetooth headset
quite often). So for peripheral equipment to cellular phones, this technology works well (due to
standardization), but for battery operated sensors and similar it has its limitations.
Summary
Ease of use
Mesh
Connection with IP world
Interoperability
Development cost and
time to market
i
ii
RC232
☺☺☺
No
☺
No
☺☺☺
ZNM
☺☺
Yes
☺☺
Yes
☺☺
ZigBee
☺
Yes
☺☺
Yes
☺
802.15.4
☺
Noi
☺
No
☺
6LoWPAN
☺
Yes
☺☺☺
Yesii
☺
Mesh functionality can be implemented on top of the 802.15.4 stack by the user
Interoperability is on IP level, not on application level.
References
[1] AN003 Implementing ZigBee/802.15.4 Solutions on Radiocrafts modules
©2008 Radiocrafts AS
White Paper WP003 (rev. 1.0)
Page 4 of 5
Radiocrafts
Embedded Wireless Solutions
Document Revision History
Document Revision
1.0
WP003
Changes
First release
Disclaimer
Radiocrafts AS believes the information contained herein is correct and accurate at the time of this printing. However,
Radiocrafts AS reserves the right to make changes to this product without notice. Radiocrafts AS does not assume
any responsibility for the use of the described product; neither does it convey any license under its patent rights, or
the rights of others. The latest updates are available at the Radiocrafts website or by contacting Radiocrafts directly.
As far as possible, major changes of product specifications and functionality, will be stated in product specific Errata
Notes published at the Radiocrafts website. Customers are encouraged to check regularly for the most recent
updates on products and support tools.
Trademarks
RC232™ is a trademark of Radiocrafts AS. The RC232™ Embedded RF Protocol is used in a range of products from
Radiocrafts. The protocol handles host communication, data buffering, error check, addressing and broadcasting. It
supports point-to-point, point-to-multipoint and peer-to-peer network topologies.
ZigBee® is a registered trademark of the ZigBee Alliance
All other trademarks, registered trademarks and product names are the sole property of their respective owners.
Life Support Policy
This Radiocrafts product is not designed for use in life support appliances, devices, or other systems where
malfunction can reasonably be expected to result in significant personal injury to the user, or as a critical component
in any life support device or system whose failure to perform can be reasonably expected to cause the failure of the
life support device or system, or to affect its safety or effectiveness. Radiocrafts AS customers using or selling these
products for use in such applications do so at their own risk and agree to fully indemnify Radiocrafts AS for any
damages resulting from any improper use or sale.
© 2008, Radiocrafts AS. All rights reserved.
Contact Information
Web site: www.radiocrafts.com
Email: [email protected]
Address:
Radiocrafts AS
Sandakerveien 64
NO-0484 OSLO
NORWAY
Tel: +47 4000 5195
Fax: +47 22 71 29 15
E-mail: [email protected]
©2008 Radiocrafts AS
White Paper WP003 (rev. 1.0)
Page 5 of 5
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