At present, the communication between people can already be done conveniently and cheaply, and the communication between people and things is in the ascendant. In the era of the Internet of things, if you want to realize the Internet of things, the first is to choose what kind of wireless connection technology.
In the Internet of Things (IoT), wireless connectivity technologies are diverse and their strengths, future or complementarities are different for low-power wide area networks (such as NB-IoT, eMTC and LoRa) and low-power local area networks (such as Wi-Fi, Bluetooth and ZigBee) How to choose should see business needs.
Low-power WAN have their own strengths
For low-power WAN technologies, NB-IoT, eMTC and LoRa technologies are more mature technologies. Each of the three technologies has advantages and disadvantages, which can be complemented in practical application scenarios.
NB-IoT is a cellular IoT technology based on the 3GPP protocol. The bandwidth is only 200kHz and can be directly deployed in the GSM or LTE networks. Based on the licensed frequency band, NB-IoT can be deployed in-band, guard band or independent carrier to coexist with existing networks . However, the NB-IoT does not support the cell handover or redirection in the connected state, and the cell reselection can only be performed in the idle state.
NB-IoT has four major characteristics, one is wide coverage, in the same frequency band, NB-IoT than the existing GSM network gain of 20dB, equivalent to enhance the ability to cover 100 times the area; the second is the ability to support the mass connection, NB-IoT a sector can support 50000 connections; Third, lower power consumption, NB-IoT terminal module standby time up to 10 years; Fourth, low-cost, when NB-IoT module shipments over one thousand After the million, the module cost can be reduced to 5 dollars or less.
eMTC is also a cellular Internet of Things (IoT) technology with a bandwidth of 1.4MHz and up to a maximum of 1 Mbit / s peak rate for uplink and downlink. It supports richer applications such as VoLTE and supports connected cell switching. The existing network can be upgraded with 4G network software Way to achieve. However, the coverage of eMTC is 9dB worse than that of NB-IoT, which consumes more power than NB-IoT and the number of connections is low.
LoRa uses an unlicensed ISM frequency band. It has a simple network architecture and low operation cost. Its maximum coverage range is up to 20 km and data rate is up to 50 kbit / s. The module has low power consumption and low cost and can be self-organized. But LoRa is likely to cause network congestion based on unlicensed bands.
From a technical point of view, NB-IoT more suitable for meter reading and other services, eMTC more suitable for people to communicate, and LoRa based on unlicensed band, more suitable for ad hoc network. In the future, enterprises can choose the appropriate technology according to the application scenario.
Low-power LAN have their advantages
In low-power LAN, Wi-Fi, Bluetooth, ZigBee is a more mature technology, more suitable for smart home environment applications.
Bluetooth is commonly used in wearable devices. Up to now, the latest transmission speed of Bluetooth 5.0 is limited to 2 Mbit / s. Theoretically, the effective working distance between Bluetooth transmitting and receiving devices can reach 300 meters. Bluetooth technology is fully supported mesh mesh network, can provide many-to-many device transmission, and especially improve the communication efficiency of building a wide range of network coverage for building automation, wireless sensor networks need tens of thousands of devices in a reliable, IoT solution for secure transport of the environment.
In terms of terminals, Bluetooth technology has the advantage of low cost. Almost a billion smartphones are produced every year with Bluetooth 4.0. Such a large volume reduces the R & D costs of Bluetooth protocols and Bluetooth hardware and software.
Wi-Fi based on the IEEE 802.11 protocol, the maximum coverage radius of up to 100 meters, the transfer rate of 54Mbit / s, but the power consumption is relatively high for large-scale, wide range of data transmission and signal coverage, Wi-Fi is a high data rate The best choice for applications that can deliver audio and video streams.
Based on the IEEE 802.15.4 protocol, ZigBee can embed a variety of devices with a maximum propagation speed of 250 kbit / s and a coverage area of ​​75 meters. The low power consumption, low cost and self-organizing network make the protocol easy. Compared with the point-to-point transmission mode of Bluetooth, ZigBee protocol has the advantage of self-networking capability, supporting up to 65,000 devices. For smart home, ZigBee protocol security is high, so far there is no world together to crack precedent.
As can be seen from the technical features, Bluetooth is more suitable for applications in personal wearable devices and the communication between people and the surrounding objects, Wi-Fi is more suitable for large-rate transmission, and ZigBee more applications in the sensor information transmission. From this we can see that low-power WAN technologies can also be integrated with low-power LAN technologies in the future to form a complementary trend to meet more business needs.
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