Although the LoRaWAN wireless technology was built by the experts of LoRa Alliance (mainly Semtech, IBM, Actility), it ignores the complexity of technology and the high cost of hardware, and has defects in the following technical transmission.
1. Public bandwidth + public standards = vulnerable to attacks industrial iot gateway
LoRaWAN works on the free bandwidth of ISM (ISM), whose protocol specification is public, which brings the problem of being vulnerable to attack. It is difficult to "forge" an End Node. The attacker listens to the 4-byte DevAddr. When using this address to send a message, the gateway is a network server (NS of one of the four servers of Lora wan server).
Another attack is "malicious crowding". Imagine that if an attacker uses a LoRa device to send a preamble of the maximum length with a bandwidth of 125kHz, the channel will be maliciously occupied. As long as the attacker protects the duty cycle and transmission power, this attack is "legal". Policies or industry regulations may be needed to protect LoRaWAN from congestion attacks.
2. The inefficiency of the asynchronous ALOHA protocol
The state of Hawaii in the United States is an archipelago, and the cost of laying a wired network is very high. Using wireless technology allows users on each island to use the central computer. This project was in charge of by the University of Hawaii in 1968, and it is the earliest wireless computer communication network in the world. This communication protocol is called aloha, which is the greeting that people in Hawaii say hello to.
The principle of the protocol is very simple. If the user has data, let him send it. If the response is received within the specified time, it means the sending is successful, otherwise resend.
Resend strategy: Wait for a random time before resending. If a collision occurs again, wait a random amount of time until the resend succeeds.
Pros: Easy to implement.
Disadvantages: extremely easy to conflict
Efficiency: The maximum channel utilization rate of pure ALOHA protocol is below 18.4% (1/2e)
Today, the host Class A of LoRaWAN also adopts the ALOHA protocol. While saving power and simplicity, conflicts and low efficiency are inevitable. Fortunately, the sensor's communication data and frequency are not high, and SX1301 can provide multi-channel FDMA (Frequency Division Multiplexing), which can effectively alleviate conflicts.
Post je objavljen 30.11.2022. u 10:46 sati.