After the read, you will learn:
What is Wifi?
What is Lora?
Wifi communication and Lora technology comparison.
Which one is more suitable?
1. Wifi communication
1.1. What is wifi?
wifi is a wireless local area network WI-FI (Wireless Fidelity, wireless fidelity) technology is a brand of wireless network communication technology based on the IEEE 802.11 series of standards.
The purpose is to improve the interoperability between wireless network products based on the IEEE 802.11 standard. Owned by the Wi-Fi Alliance, WIFI is simply a wireless networking technology.
Wi-Fi is a technology that allows electronic devices to connect to a wireless local area network (WLAN), usually using 2.4G UHF or 5G SHF ISM radio frequency bands. Connecting to a wireless LAN is usually password-protected; but it can also be open, which allows any device within the range of the WLAN to connect.
1.2. The structure of WiFi
Generally, the basic equipment for setting up a wireless network is a wireless network card and an AP, so that network resources can be shared in a wireless mode with the existing wired architecture, and the cost and complexity of the installation are much lower than that of the traditional wired network.
If it’s just a peer-to-peer network of several computers, you don’t need an AP, just each computer is equipped with a wireless network card. AP is the abbreviation of Access Point, which is generally translated as a wireless access point or bridge.
It is mainly in the media access control layer MAC play wireless workstations and bridges for wired local area networks. With AP, just like the Hub of a general wired network, wireless workstations can be connected to the network quickly and easily.
1.3. Technical characteristics of Wifi
1.3.1. Advantages
(1) Its radio wave coverage is wide, and the WiFi radius is up to 100 meters (theoretical value), which is suitable for use in unit floors and offices. Bluetooth technology can only cover less than 15 meters.
(2) Not only the speed is fast, but also the reliability is high
The 802.11b wireless network specification is a variant of the IEEE 802.11 network specification. The highest bandwidth is 11Mbps. In the case of interference or weak signal, the bandwidth can be adjusted to 1Mbps, 5.5Mbps, and 2Mbps. The bandwidth is automatically adjusted to effectively ensure the reliability and stability of the network.
(3) Wireless network
The main advantage of Wi-Fi is that it does not require wiring and is not restricted by wiring conditions. Therefore, it is very suitable for the needs of mobile office users and has a broad market prospect.
(5) Health and safety
The transmission power set by IEEE802.11 cannot exceed 100 milliwatts, and the actual transmission power is about 60-70 milliwatts. The transmission power of a mobile phone is about 200 milliwatts to 1 watt, and a handheld walkie-talkie is as high as 5 watts. The wireless network is not used in a way that the mobile phone directly touches the human body, which has a certain degree of safety.
1.3.2. Weaknesses
The IP wireless network currently in use has some shortcomings, such as long handover time, small coverage radius, low bandwidth, etc., making it unable to support mobile VoIP and other demanding applications.
Because the wireless network system is not open to the development of upper-layer services, it is difficult to develop many services suitable for the IP mobile environment. WLAN products targeted at home users cannot meet the requirements of operators in network maintenance and operation in many places.
1.3.3. Wifi security
Under the premise that wifi provides a large number of applications, network security is an issue worthy of our attention. On the one hand, WiFi has given us many ways to access the internet. So that we have the unlimited resources of the Internet; on the other hand, wifi also gives us bring a lot of security issues, and various network hackers, viruses, attacks, etc. may threaten our online transactions at any time.
As a popular communication protocol, the Wifi communication protocol has more connected users and also brings more security risks. The security risks of wifi come from two aspects: on the one hand, it comes from the attack of the network. On the other hand, it comes from the trap of the network.
The security risks of wifi are mainly: (1) malicious phishing AP; (2) access attack; (3) Dos and DDoS attacks.
2. LoRa communication
2.1. What is LoRa?
Lora is a kind of low-power wide-area network communication technology. It is an ultra-long-distance wireless transmission technology based on spread spectrum technology adopted and promoted by Semtech.
It is a unique modulation format produced by Semtech’s radio frequency part. The core chips of the LoRa RF part are SX1276 and SX1278. This type of chip has a small integrated scale and high efficiency, which brings high receiving sensitivity to the LoRa wireless module.
The gateway chip uses the SX1301 with higher integration and more channels. The LoRa gateway developed with SX1301 as the core can form a complex multi-node self-organizing network with many LoRa modules.
2.2. Is LoRa a Mesh network, point-to-point transmission, or a star network?
The LoRa modulation technology itself is a physical layer (PHY layer) protocol, which can be used in almost all network technologies. Although the Mesh network expands the network coverage, it sacrifices network capacity, synchronization overhead, and battery life.
With the simultaneous improvement of the LoRa technology link budget and coverage distance, the Mesh network is no longer suitable, so the star-shaped networking method is used to optimize the network structure, extend the battery life, and simplify the installation.
The LoRa gateway and the modules are networked in a star network, while the LoRa modules can theoretically be networked in a point-to-point polling manner. Of course, the efficiency of point-to-point polling is much lower than that of a star network.
2.3. What is a LoRa gateway?
The LoRa gateway is located at the core of the LoRa star network. It is an information bridge between the terminal and the server and is a multi-channel transceiver. LoRa gateways are sometimes called LoRa base stations or LoRa concentrators.
Although the definitions are different, they actually have the same meaning. The LoRa gateway uses different spreading factors, and the different spreading factors are orthogonal to each other, so in theory, multiple signals with different spreading factors can be demodulated in the same channel.
The gateway and the network server are connected through a standard IP, and the terminal communicates with one or more gateways through a single hop. All terminal communication is two-way communication, and it also supports remote software upgrades. Currently, the definition is different, and the gateway type is also different.
For example, according to different application scenarios, it can be divided into indoor gateways and outdoor gateways; according to different communication methods, it can be divided into full-duplex gateways and half-duplex gateways; and according to different design standards, it can be divided into gateways that are fully compliant with the LoRaWAN protocol and those that are not. Fully comply with the LoRaWAN protocol gateway.
AUGTEK’s new generation gateway is outdoor, full-duplex, and fully conforms to the LoRaWAN protocol. LoRa gateways and LoRa terminals that are fully compliant with the LoRaWAN protocol can achieve interconnection, which is of great significance!
2.4. What is the capacity of the LoRa gateway? How many terminals can be connected to a single gateway?
Gateway capacity refers to the ability of the gateway to receive the number of data packets within a certain period of time. In theory, a single SX1301 chip has 8 channels and can receive up to 15 million data packets per day when it is fully compliant with the LoRaWAN protocol.
If the frequency of sending packets for a certain application is 1 packet/hour, a gateway composed of a single SX1301 chip can access 62500 terminal nodes. Of course, this is only a theoretical value, and the number of gateway access terminals is ultimately closely related to the number of gateway channels, the frequency of terminal packet transmission, the number of packet bytes, and the spreading factor.
2.5. What factors does the number of nodes connected by the LoRa gateway depend on?
The number of nodes accessed by the LoRa gateway depends on the channel resources that the LoRa gateway can provide and the channel resources occupied by a single LoRa terminal. If the LoRa gateway adopts the Semtech standard reference design and the gateway adopts the SX1301 chip, the number of channels is fixed 8 uplink channels and 1 downlink channel.
The number of physical channels is determined, and the channel resources that the LoRa gateway can provide are also determined. (The gateway design is different, the number of channels is different, AUGTEK gateway can realize 8 uplinks, and 4 downlinks.)
The channel resource occupied by a single LoRa terminal is the same as the time the terminal occupies the channel, which is closely related to the terminal’s packet-sending frequency, the number of packet bytes, and the spreading factor of the LoRa terminal.
When the frequency of sending packets and the number of bytes sent by the LoRa terminal increase, the time that the terminal occupies the channel for sending and receiving will increase, which will occupy more channel resources.
When the LoRa terminal uses a larger spreading factor, the signal can be transmitted farther, but the cost is that it will take more time to transmit the unit byte of information.
2.6. What is a LoRa terminal or node?
The LoRa terminal is an integral part of the LoRa network and is generally composed of LoRa modules and sensors. The LoRa terminal can be powered by batteries and can be remotely located. Every terminal conforming to the LoRaWAN protocol can directly communicate with the gateway conforming to the LoRaWAN, thereby achieving interconnection.
2.7. Will LoRa gateways use free frequency bands, will they be susceptible to frequency interference?
The anti-interference ability depends on the characteristics of the LoRa technology itself and the design of the gateway. LoRa technology itself has super high receiving sensitivity (RSSI) and super signal to noise ratio (SNR). Take AUGTEK’s LoRa gateway and LoRa module as an example, its receiving sensitivity reaches an astonishing -142dBm, and the super-strong signal-to-noise ratio can make AUGTEK gateway and terminal work 20dB below the noise threshold.
In addition, the AUGTEK gateway uses frequency hopping technology to perform frequency shift keying through a pseudo-random code sequence, so that the carrier frequency continuously hops and spreads the spectrum to prevent fixed frequency interference.
2.8. What is the data transmission rate of LoRa?
The LoRaWAN protocol defines a series of data transmission rates. Different chips have different rate ranges. For example, SX1272 supports 0.3-38.4kbps, and SX1276 supports 0.018-38.4kbps. At present AUGTEK can achieve a transmission rate of 0.3-37.5kbps. 12. Is there a limit to the length of data sent or received using LoRa devices? There are limitations.
Theoretically speaking, SX127x series chips have a 256 Bytes FIFO, which can transmit or receive 256 Bytes. However, not the load length of the LoRa module can be 256 Bytes at any transmission rate. In the case of a low transmission rate,
It takes a very long time to transmit 256 Bytes at a time (it may take several seconds or even longer), which is not conducive to anti-interference and interaction. Therefore, in technical processing, it is generally recommended that users divide long data into several small data for transmission.
Comparison Of Wifi Communication And Lora Technology
Comparison of LoRa and wifi communication methods
The smart fire protection system adopts the Lora networking communication method, using Lora’s faster response speed, long-distance transmission, more networking nodes, and low-power wireless network technology to return the monitoring data of the front-end detection device to the monitoring center in real-time.
Features of the LoRa communication system:
Transmission characteristics, LoRa is a long-distance, low-power, low-data rate, anti-interference wireless network technology.
Security, LoRa provides data integrity checking and authentication functions, the encryption algorithm adopts general AES-128, supports AES-128 encryption and has two independent security layers and a network session key
(NwkSKey) and an application session key (AppSKey)
Connection characteristics: No base station is used, and the number of pure LoRa networking can reach more than 1000.
Comparison table of the LoRa communication system and Wifi ring network communication system:
| Performance/Category | Lora | Wifi | advantage |
|---|---|---|---|
| Transmission bandwidth | LoRa maximum 37.5KB transmission distance up to 10km | 100Mbps transmission distance 100m (unobstructed) | The wifi communication bandwidth is larger to meet the transmission demand. LoRa has a smaller bandwidth, but a longer transmission distance, meeting the communication needs of smart fire equipment |
| Safety | Security, LoRa provides data integrity checking and authentication functions, supports AES-128 encryption and has two independent security layers, a network session key (NwkSKey) and an application session key (AppSKey) | Both the smart fire communication system and the wifi wireless AP adopt encryption authentication measures to ensure the confidentiality and integrity of communication. | Encryption protocols are used to meet communication security requirements. LoRa has two independent security layers for higher security |
| Reliability | Without base station, the number of pure LoRa networking can reach more than 1000 | The theory supports 254 nodes, but the stability decreases after the actual measurement exceeds 20 | LoRa supports more nodes and reserves more space for later |
| Practicality | Based on the low-power module design, it can be powered by a long-term battery, eliminating the need for wiring, and has better environmental adaptability | The high power consumption module requires a power cord, which has higher environmental requirements | LoRa adopts low-power design, which is more energy-efficient |
Summary
Lora and Wifi communication systems have their respective strengths, and Wifi communication systems provide greater communication bandwidth. Lora is more stable in actual use and can better meet the actual needs of smart fire protection engineering.
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