Due to the rise of smart homes, everyone now has more or less smart homes in their homes. Whether it is speakers, fans, sockets, or switches, it seems that every device in home appliances can become intelligent.
With so many devices gathered in the same home environment, what protocol smart hardware device should users buy?
Today, let’s discuss the three most popular communication protocols in the smart home Internet of Things, Zigbee, WiFi and BLE (Bluetooth). And when you choose a smart home, how should you choose the hardware protocol.
First, let’s talk about these three transmission protocols
1. WIFI is currently the most widely used wireless communication technology. The transmission distance is 100-300M, the rate can reach 300Mbps, and the power consumption is 10-50mA.
2. Zigbee, the transmission distance is 50-300M, the rate is 250kbps, and the power consumption is 5mA.
3. Bluetooth, the transmission distance is 2-30M, the rate is 1Mbps, and the power consumption is between zigbee and WIFI (5-50mA).
These three wireless technologies, in terms of transmission distance, are WIFI>ZigBee>Bluetooth; in terms of power consumption, they are WIFI>Bluetooth>ZigBee, and the latter two can only be powered by batteries; in terms of transmission rate, they are WIFI > Bluetooth > ZigBee.
At present, the advantage of WIFI is that it is widely used and has been popularized to thousands of households; the advantage of ZigBee is low power consumption and self-organizing network; the advantage of Bluetooth is that it is simple to form a network.
WiFi
Everyone is very familiar with WiFi, because the built-in network protocols in most people's mobile phones are adapted to WiFi.
The advantages of WiFi: the speed is relatively fast, the transmission data is large, and the user's first experience is very good. Smart devices with WiFi can be easily connected to mobile phones, and can seamlessly communicate with mobile phones on the Internet.
Disadvantages of WIFI: power consumption. Generally, the standby power consumption of WiFi devices is about 1W, while the general standby power consumption of BLE devices and Zigbee devices is within 0.1W. In comparison, the power consumption of WiFi devices is high. A lot came out. In addition, the number of connected WiFi smart devices is also a relatively large problem. In theory, the upper limit of the number of WiFi connected is mainly determined by the number of nodes in the router. As far as the current home router is concerned, if there are more than dozens of electronic devices that need to be connected to the router, the router will basically not be able to bear it, and it will not even be able to connect to WiFi.
Zigbee
Advantages of Zigbee: short-distance, low-power wireless communication protocol, the biggest advantage is that it can automatically form a device network and link the direct data transmission of each device. The access limit of Zigbee is also very high. In theory, the number of Zigbee network nodes can reach up to 65,000!
Disadvantages of Zigbee: But in this self-organizing network, a central node is required to manage the entire Zigbee network, which means that there must be a component similar to a "router" in the Zigbee device network to connect various devices together to achieve Linkage effect between Zigbee devices. And this additional "router" component is what we call a gateway.
BLE
Advantages of BLE: It is equivalent to the middleman between WiFi and Zigbee. It not only has the low power consumption of Zigbee (lower power consumption than WiFi), the characteristics of fast response, but also the advantage of easy use of WiFi (you can connect to it without a gateway) Mobile phone network), especially in the use of mobile phones, the current Bluetooth protocol, like WiFi, has become a standard protocol in smart phones.
Disadvantages of BLE: The ability to penetrate walls is weak, and the signal is very weak behind the partition wall. Unable to link. Moreover, it cannot access the Internet, and is limited to LAN transmission within a certain space.
Comparison of wireless technology applications
The emergence of Bluetooth technology makes short-distance wireless communication possible, but its protocol is more complex, high power consumption, and high cost are not suitable for industrial control and home networks that require low cost and low power consumption. In particular, the biggest obstacle of Bluetooth is the limited transmission range, the general effective range is about 10 meters, weak anti-interference ability, information security issues and other issues are also the main factors restricting its further development and large-scale application.
Wi-Fi technology is also a short-distance wireless transmission technology, which can access wireless signals at any time, has strong mobility, and is more suitable for applications in office and home environments. Of course, Wi-Fi also has a fatal flaw. Because Wi-Fi uses radio frequency technology, it sends and receives data through the air, and uses radio waves to transmit data signals, so it is relatively susceptible to external interference. Data packets can be detected or received by the outside world during transmission. Information security is a hidden danger. Although data can be encrypted and transmitted, there is still the possibility of being cracked by hackers if there are enough data packets.
ZigBee technology is an internationally accepted wireless communication technology. Each of its network ports can be connected to more than 65,000 ports at most, which is suitable for use in many fields such as home, industry, and agriculture, while Bluetooth and Wi-Fi network ports can only connect to Entering 10 ports obviously cannot meet family needs. ZigBee also has the advantages of low power consumption and low cost. In low power consumption standby mode, two ordinary AA dry batteries can be used for more than 6 months.
Advantages of ZIGBEE in smart home system
The application of Zigbee technology in smart home has the following advantages.
Strong anti-interference ability: Zigbee transceiver module uses 2.4G direct-sequence spread spectrum technology, which has better anti-interference ability than general FSK, ASK and frequency hopping data transmission stations.
Good confidentiality: ZigBee provides data integrity check and authentication functions, the encryption algorithm adopts the general AES-128, and the 128-bit password guarantees the confidentiality of ZigBee signal transmission.
Fast transmission speed: ZIGBEE transmits data in short frames, so the transmission speed is fast and the real-time performance is strong.
Strong scalability: ZIGBEE is easy to network and has strong self-recovery ability. Therefore, it is easy to expand in smart homes and add new devices.
At present, there are more than 100 smart home single product manufacturers on the market. Generally speaking, the principles of smart device selection agreement are as follows:
1) Plugged-in devices, using the WiFi protocol;
2) If you need to interact with the mobile phone, use the BLE protocol;
3) The sensor uses Zigbee.
Therefore, more smart home manufacturers will use the three protocols together. The advantage is that it can adapt to the transmission and communication of any protocol, and it is possible to integrate the products of the three protocols. The disadvantage is also obvious, that is, the three protocols The two protocols are not connected to each other, resulting in more mistakes in the delay of receiving signal feedback, resulting in no timely feedback during use, and instead causing users to not only fail to enjoy the convenience brought by smart home during use, but on the contrary Increased burden.
So when you buy smart home equipment, you must pay attention to the following points:
When purchasing a "Zigbee version" device, you must make sure that you have a Zigbee gateway at home, otherwise most single Zigbee devices cannot be directly controlled by a mobile phone.
For WiFi/BLE devices, most WiFi/BLE devices can directly connect to the mobile phone network without a gateway, unlike Zigbee version devices, which must have a gateway to connect to the mobile phone. You can choose WiFi and BLE devices at will.
BLE devices generally interact with mobile phones at close range, and the signal behind the partition wall is not very good, so it is not recommended to purchase "only" BLE protocol for devices that require remote control.
If the home router is just an ordinary home router, it is not recommended that smart home devices use the WiFi protocol in large quantities, because it is very likely that the device will always be offline. (Because of the limited WiFi access nodes of ordinary routers, connecting too many WiFi devices will affect the normal WiFi connection.)
ZigBee smart home two-way interaction
It is worth noting that many smart homes currently on the market also use the banner of wireless, but customers find that in the process of using them, they clearly send instructions, but the execution effect is greatly reduced, which is not satisfactory. For example, when leaving home in the morning, The owner dialed the "leave home" mode on the mobile phone, with the intention of turning off all electrical appliances and lights, and activating the smart security function. However, due to unstable signal, it is likely that the security function was not implemented, so that the criminals broke into the door and the home was closed. The sensor did not send out the alarm signal in time.
It turns out that many smart homes using 433M/315M wireless radio frequency technology now only have one-way communication function, that is, they can only know that the control signal has been sent successfully, but whether the operation command of the controlled signal is actually executed, whether the controlled device has been turned on or not. Closed, there is no way of knowing. Obviously, this kind of information feedback transmission mode that cannot confirm the receiver can no longer meet the market demand. Two-way communication technology must be used, that is, when the signal is successfully sent, the receiving device will immediately feed back the received signal to the transmitter, and also That is, the receiver has both the receiving function and the transmitting function. As a wireless two-way communication technology, ZigBee has a self-detection function. For example, it can feed back and query the switch status of lights and electrical appliances at any time. If it is a light, you can also query the brightness level of the light. , you can query the allocation of addresses in the system.
The wireless smart home based on ZigBee technology adopts a collision avoidance mechanism. When the owner sends a control command with a handheld device, the receiver will immediately reply with a confirmation message. If no confirmation message is received, it means that a collision has occurred. The control command will be issued again until the receiver replies with a confirmation message, making the transmission of the system very reliable. The smart home operation software launched by Wulian Sensing has more command confirmation and reply functions than the same type of software on the market. After each command is executed, the software interface has a confirmation and prompt of the execution effect.
