2.4G wireless in industrial and medical applications

Community development, wireless advantages are gradually emerging.

Such as: wireless communications coverage, almost without geographical restrictions; wireless communication can be set up, ready to increase link, installation, convenient; wireless communication can be quickly (tens of minutes) from the communication links established to implement temporary, emergency, disaster communication; and wired communications will have geographical restrictions, a longer response time. Wireless communication in reliability, availability, and the survivability aspects beyond the traditional wired communication ways, especially in some special geographic environment, more superiority. As wireless technology matures, industrial, medical and other industries have begun to increasingly use 2.4G communication, 802.15.4, ZigBee and Wi-Fi also get more applications. ZigBee and Wi-Fi respective has distinct features, and many of the characteristics of the complementary and together, they have a very good prospect. For the helped engineer friend close to answer more design and applications encountered problems, this month's expert sitting Hall invite to Beijing Boxun technology co., Ltd Technical Director Liu Kai to share his experience in the design.

Friends of the month: ZigBee, Wi-Fi?

ZigBee, Wi-Fi, Bluetooth and wireless technology comparison as shown in the table below:

ZigBee, Wi-Fi, Bluetooth and wireless technology comparison

Wi-Fi has bulk use, mainly in the home and Office environment for PC such as local area network.

3G deployment, there will be some 3G + Wi-Fi, China Telecom's "Tianyi" includes this section. You can anticipate a lot of embedded Wi-Fi equipment will also be more universal network easily, such as Wi-Fi POS machine and supermarket Wi-Fi weighing apparatus, etc. The application is also now the industrial environment, mainly in the serial port device Wi-Fi access for industrial wireless data collection system.

ZigBee and IEEE802.15.4 equipment mainly focus on: industry wireless sensor detection, low level control; personal care appliances, low-power wireless medical equipment; high-end toys; electrical networks and control; wireless consumer devices; HVAC and lighting controls, etc.

The current batch of applications mainly in the asset tracking, logistics management, intelligent lighting, remote control, medical care and remote meter reading system.

Íøóñ £ UCanDoIt 2.4G technology is how to solve the problem of the frequency band crowded?

802.15.4 uses DSSS, 802.11 uses DSSS and OFDM.

Actual use, we tested office buildings, factories, and other environments. Communication more affected by the barrier and distance, congestion without causing too much of an impact.

Íøóñ £ 802.15.4, Zigbee jackywoo technology is the most ideal WSN network, with a low-power features, but how to achieve low power consumption, you need to consider what factors?

IEEE 802.15.4 defines an optional MAC layer Super frame structure, Super frames including active (Active) and non-active (Inactive) in two parts in non-active part of the device can enter low power mode (hibernation); in active section is divided into competition and non-competition period, the competition period provided for in the way access CSMA-CA equipment use, non-competition period consists of several security slot, to certain needs to retain a certain data bandwidth devices this hyper-frame structure reflects the IEEE 802.15.4 low-power characteristics of a large, non-active phase of the introduction of limited device transceiver for opening hours, in the absence of data transmission when they are in hibernation, which greatly saves power.

Zigbee device into a fully functional devices and functions, streamlining functionality relative full function device protocol stack simple and less memory, but a full-function devices and interact and full function device has complete IEEE 802.15.4 Protocol features, with its transmission to any node within the interaction of two devices are combined, can form a mesh network, Star network and tree network.

Low-power system in addition to the transmission for power consumption, the CPU and other parts of the system also has the power relations.

For example, you can turn off JN5139 RF SoC itself, run some CPU alone. You can also turn off on-chip SoC ADC, serial, and other peripherals. For Hibernate can provide for quick start the contents of the hibernation reserved RAM, use break/comparators/Timer sleep and wake-on-can only be Reset to wake up to a depth of hibernation mode. This entire system to a reasonable functionality and power balance.

Netizen wind + cloud: Zigbee signal bandwidth?

ZigBee's underlying use IEEE802.15.4, i.e. physical bandwidth bandwidth is IEEE802.15.4? that is 250kbps.

However, physical bandwidth and effective data rate is different. For ZigBee, data rate, but also the network topology, data routing, network data. Real application must take full account of these factors. Because there are many factors involved, so there will not be able to give the actual calculations. Experience, the routing of the data rate. Each additional level routing increases the time 100ms ~ 200ms. So said ZigBee is not a real-time network. Second, network with data on the rate at which also have a greater impact. In short, the ZigBee application suitable for low-speed sensor, the actual bandwidth to take into account the actual situation of the network.>