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Walking from GPRS to LoRa
Date:2018/11/21  Click:99 times

And how to do it for digital agriculture step by step



In the field of digital agriculture, how does the communication of intelligent devices evolve from GPRS to LoRa?

In the article, we talked about the digital agriculture in different communication modes, finally we choose the LoRa LPWAN.
From the perspective of end users and companies, what is the difference between GPRS and LoRa? The difference is really great because there is nothing in common.  

Switching from GPRS to LoRa means that almost all the products need to develop, but it is more important to change the related business idea.

The installation of GPRS is plug and play, and customers can complete it autonomously. LoRa needs to install gateway devices, and each device must have authorization and radio communication. From the beginning of network topology planning considering the gateway number and where to install, which requires a professional installation engineer or training of customers, quality of the radio signal will be affected by different environment and engineering, such as natural or man-made barriers, even plants or artificial buildings. Compared with LoRa technology, GPRS technology does not have such problems.  


1. Gateway requirements


The highest and the most important part of the cost of LoRa network is the gateway, the gateway actually replaced the role of tower in the GPRS network, industrial grade outdoor gateway can cost up to $1000. In agriculture, LoRa network is relatively sparse, which means that a large number of areas can be covered with a small number of devices. If 2 gateways can cover the 10KM rural area, that is equivalent to 2 gateways per 3000 hectares of land. In practical applications, we can think of 2 gateways for every 200 hectare of land. 


2. Network connection requirements


Gateways require permanent network connections, such as telephone lines, 4G networks, or WiFi.


3. Electricity demand


The need for power facilities and powerful permanent network connection, the vast majority of the gateway is designed according to the power system, without considering the optimization of power consumption. The typical 4G gateway consists of LoRa gateway and 4G router. 

4. LoRa server requirements 


 rent from our imagination, although there are gateways and terminal devices, it is not enough. Basically, the gateway software only between the LoRa and HTTP protocol conversion transfer packets between the Web server and the terminal equipment, the key component is a special layer within the LoRa server distribution platform in the Web side. LoRa server has many functions such as controlling the whole network, transmitting data to the application system and so on. In addition, the LoRa server can also remove duplicate packets, determine the communication channel and transmitting power nodes, storage network and server data packets. In other words, the gateway is a virtual data converter between the terminal device and the LoRa server. This design has its advantages and disadvantages, should ensure the gateway is simple and practical, strong compatibility and low price etc.. However, this is not the case. I hope that as the product increases, the price will decrease. 


The server software is very complex and not easy to use, so in many cases, the best use of related services to provide third party service providers. The current market there are many of these companies, such as The Things or Network Loriot, many new companies and products will continue to emerge, they may be in accordance with the gateway or the number of terminals monthly fees and provide other choices, application server can communicate through HTTP API or MQTT LoRa server and third party. 


5. MQTT demand 


Another new technology in the LoRa application scenario is MQTT (Message Queue Transport). Strictly speaking, it is not part of the LoRa protocol standard, it is optional. MQTT is one of only a few code footprint streamlined version of the information broker, it can be used in any system, so that the message exchange between the device and the software module, module and other modules can subscribe to MQTT for information exchange. All existing LoRa servers can exchange data with application end servers through HTTP API and MQTT. 


Why don't we consider using MQTT instead of HTTP API? The problem is that HTTP is a server API, and the application must acquire new data through regular queries. In this way the efficiency is not high, we hope that the LoRa server in the data arrived immediately will be pushed to the user application data. This is the information broker can do, some types of message application subscribers and sorted by the broker lined up these messages will be automatically push. To sum up, the LoRa server has supported MQTT. We only need to add the MQTT client to the application. 


6. Summarize the work we need to do from GPRS to LoRa: 


Firstly, from the perspective of development

(1) Develop terminal equipment using LoRa C class communication;

(2) Choose suitable gateway for application;

(3) Install LoRa server or purchase subscribers from third party; 

(4) Add MQTT to support application. 


Secondly, from a commercial perspective 

(1) Increase the cost budget, set up the installation process and register terminal equipment for installing 1-2 gateways every 5 kilometers; 

(2) Prepare technical support departments for equipment installation and provide LoRa network technical services; 
(3) Find a permanent network connection solution, such as 4G router with Ethernet port;
(4) Find the power solution of gateway and 4G router. In most cases, the gateway can be installed on buildings closest to the power lines. Under special circumstances, according to the gateway and router, can also use solar panels and batteries, but should provide at least 3-10W.

Seems difficult? In fact, once completed, there will be several.