how to design ultra low power zigbee rf4ce wireless networks

by:CTECHi     2020-04-14
Wireless technology is developing from communication between people and computers to communication between machines.
After the integration of mobile phones and wireless Internet almost everywhere, there is a third wave of wireless (Wi-Fi)into our lives.
The third wave of wireless consists of wireless sensing and control networks that connect and control a variety of devices in our homes and businesses
From the refrigerator to the light switch, from the consumer electronics (TV, DVD-player)
And remote controls for sensors, detection or protection, and central door locks and window locks in our homes (
Like we used to in the car).
Unfortunately, with today\'s wireless technology, most of these wireless sensors and controls need to use a lot of batteries to cause environmental problems (
Think of toxic chemicals and heavy metals)
And serious maintenance problems (
Constant battery replacement).
Therefore, very interested in ultra-low power wireless networks with very low power requirements.
This includes systems that can drain a single battery during the life of the device, as well as wireless networks and sensors that can be powered by energy collection (
Sometimes called energy removal).
Creating ultra-low-power wireless networks and systems that can drain the energy available in the environment rather than the battery is a very exciting emerging technology.
Last year, ZigBee cooperated with several of the world\'s largest consumer electronics companies (
Panasonic, Philips, Sony and Samsung)
Forming the so-called ZigBee RF4CE (
Radio frequency of consumer electronics).
This industry partnership marks the development of a new generation of remote control devices --
For TV, home, and office automation, for many other types of remote control products, these products pass through low-power RF instead of IR decades ago (infrared).
By using these new communications technologies, we will soon see a wide variety of remote devices that can not only interoperate between brands and models, but require only very little power, so their batteries will never be replaced or charged.
It is even possible to design and manufacture remote controls that do not require any batteries at all and get energy from the energy collection.
The challenge of wireless sensor networks the biggest technical challenge to develop these ultra-low power sensor networks is to manage energy consumption without reducing the range or functionality such as speed and standard compliance.
Therefore, eliminating battery replacement will simplify maintenance and provide a higher degree of ease of use and safety.
Super low power consumption is obvious, current consumption-milli-amps -
Task loops are important in wireless sensor networks.
However, minimizing current consumption is only part of the solution.
There are several key issues in developing low-power wireless sensor applications, but they all start with developing ultra-low-power transceiver radio chips.
By using a communication controller-centric chip design instead of a micro-controller-centric design, and synchronous wake-up
The Ups can reduce the overall power consumption by 65% or more.
Most transceiver solutions require the MCU to be turned on at all times during the transmission package.
By using the GP500 communication controller using GreenPeak technology, only the MCU is required to process the data to be transmitted or received.
Most low-power radio networks rely on a processor-centric approach that requires a micro-controller to handle all the intelligence of the transceiver.
This requires the micro-controller to remain awake for the entire time, which in turn requires additional power.
By using a more energy-efficient communication controller approach, the transceiver can transmit and receive data independently of the microprocessor, which is only awakened and used when further processing of data is required.
By using hardware-based schedulers and synchronizers inside the chip, the radio will only wake up as needed to see if there is any data that needs to be sent.
If not, it will get back to sleep.
If you want to send data, the controller wakes up the micro-controller.
The chip then communicates the message and then goes back to sleep until it is scheduled to wake up next time.
9999-10,000 times
There is no message to send and the controller does not need to power the microprocessor.
Each time the data is sent, the chip also sends a SYNC message to make sure they wake up together at the next duty cycle.
By having the communication controller decide when to wake up and check messages, the overall energy consumption can be greatly reduced.
Since there are schedulers and synchronizers inside the communication controller, the system will only wake up in a short period of time to see if there is a message and then return to sleep.
Allowing the microprocessor to work all the time to save more than 65% of energy use compared to typical situations on traditional transceiver devices when needed. If you multiply this individual node energy saving by a wireless network with more than 100 nodes, it is clear that the entire network will be able to use less power than the traditional microprocessor-based network.
For a commonly used wireless sensor platform, there are three typical wireless sensor node states for peak current savings.
The current level of consumption varies.
In the first state, the microprocessor and transceiver are in sleep mode (10µA).
In status 2, the microprocessor is turned on when the transceiver is in sleep (10 mA).
In State 3, both the transceiver and the microprocessor are in a wake-up state (27 mA).
When looking closely at the power consumption behavior of an electronic circuit, it is clear that what initially looks like a flat current curve is actually more similar to the mountains with peaks and valleys.
When certain functional blocks become active, they generate peak current.
When the two function blocks are opened at the same time, the peak amplitude is doubled.
The secret to reducing peak power is to carefully manage turnson and turn-
Turn off time for key functions, which can avoid double peaks.
Synchronous wake-up and sleep can reduce the power consumption of low-power mesh networks. One of the most significant differences between wireless sensor communication technology and other well-known wireless technology is the ability of sensor nodes to forward messages from downstream of the communication chain. other nodes.
This technology is called grid routing or more
Hop networks provide an effective and reliable way to span large infrastructure beyond what a single wireless link can do.
For a node to forward a message received from another node, it needs to be in wake-up and receive mode when the original wireless message arrives.
Unfortunately, the receiving mode requires so much power that it can run out of battery in a few days.
Because for most reality, the power Life is too short.
According to the regulations of most industry standards, life application is the most direct solution, which limits many
The jumping capability of the node permanently connected to the main power supply.
Under such a framework, low
Assuming the power device in the power supply-
In most cases, the down mode is unable to re-transmit messages from other devices. These low-
Power equipment called terminals
A device located at the end or beginning of a communication chain.
This frame, it combines power
Powered mesh routing equipment and lowpower end-
Device for certain applications.
For example, office lighting applications that utilize connected wireless lights and electric light switches.
The lights connected to the main power supply hold the mesh routing communication node.
The switch without power supply is the natural position of the enddevices.
Many other applications are not suitable in such a framework.
In the application of gas detection, fire detection, access control, precision breeding, battlefield monitoring, perimeter monitoring, warehouse temperature monitoring, etc.
, The power supply is not easy to get or even does not exist.
Running the power cord in these applications is costly, offsetting the benefits of wireless communication.
It takes low to solve such applicationspower multi-
Jump network, or low
In power routing, all nodes, including grid routing nodes, run at low levelspower mode.
Wake up by using \"sync-
The Up \"scheme can coordinate the receiving activities, thus eliminating the need for grid routing nodes to run continuously in the receiving mode, thus significantly reducing power consumption.
The picture below describes the lowpower-
When node A wants to send A message to node C via Node B, the route works.
All nodes in the picture are low
Power nodes, sleep most of the time.
Sleep/wake up through SYNC-
The loops between nodes increase, and when nodes expect messages from adjacent nodes, they wake up.
This allows the routing node to be in a sleep state that is almost powerless for most of the time, thus enabling the super-low-Power operation.
Obviously, more wake-up
Since adjacent nodes do not always have data to transmit, the appearance of ups will exceed the strict requirements for carrying data.
However, the additional power required to wake up regularly-
The continuous receive mode operation is not required, and ups and sync are offset by the power savings.
Since its establishment, wireless sensor technology has been
Power Electronics. Most low-
Power wireless sensor networks are designed for low Power consumption, which means they consume very little Power when turned on.
This is not enough.
By using a communication-centric transceiver chip, a wireless mesh network, and synchronous wake-up and sleep cycles, developers can now create systems that don\'t even require batteries, energy collection can be used to power sensor networks from ambient power supplies.
Standard for wireless sensor networks-IEEE 802. 15.
4 IEEE 802 is the dominant and probably the only real standard for wireless sensor transceivers. 15. 4 Specifications.
However, efforts have been made to use Bluetooth and Wi-
Fi for low power sensor applications.
In most of the cases reported, Bluetooth and W-
Fi is used in a non-
The standard way actually weaves the principle of IEEE 802. 15.
4 implemented locally in them.
IEEE 802 has been widely accepted. 15.
4 provides the best foundation for wireless sensor network applications.
Except IEEE 802. 15.
4 standard, some technical vendors have chosen to build proprietary transceivers.
The main motivation seems to be to reduce the complexity and thus the potential cost points.
However, it remains to be seen if a proprietary solution can reach enough volume to actually reach a theoretically lower cost point.
In addition, reducing complexity and sacrificing performance is performed automatically at the same time, thus limiting applicability.
Proprietary technology is vulnerable for two reasons :(1)
The technical owner controls the specifications, thus controlling the price, and (2)
Customers rely on technology owners for upgrades and uninterrupted purchases.
Even within the scope of the standard, technology providers can identify and leverage opportunities for difference.
GreenPeak, for example, has developed transceiver and network stack technologies that comply with IEEE 802. 15. 4/2.
The 4 GHz standard, but includes additional features that enable it to be used in ultra-low power applications. An ultra-low-
Power applications are defined as applications that are capable of obtaining energy from the environment through solar cells, vibration energy collectors, or any other ambient energy converters.
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