I.             Overview
GPRS is a general packet radio service technology, which can be said to be anevolutionary version of the GSM transmission data mode. The GSM transmission isperformed in a circuit-switched mode, and the GPRS uses a packet switching moderegardless of whether the device transmits data or not. The channel resourcesare only occupied when the device transmits or receives, thereby improvingresource utilization. Today, for the shortage of wireless resources, thedevelopment of GPRS has an inter-generational significance. GPRS is atechnology between 2G and 3G, so it is called 2.5G. At the same time, becauseit is transmitted in the packet mode, the billing method will be calculatedaccording to the amount of data communicated, which is a good example ofmulti-pass. Pay, the principle of paying less and paying less.

Second, thecharacteristics
The picture above shows the GPRS module introduced by Chengdu Ebyte Technology Co.,Ltd. The company also launched GPRS products such as G01 series, G02 series,E840-DTU series, etc. For the experience of these products, the advantages ofthe following GPRS are summarized.

1, timeliness isstrong
Compared with the short message service, GPRS is a real-time online state, andcan process multiple data at the same time or receive multiple detection pointswithout stopping the current working state. Ideal for systems that collect datafrom multiple target points simultaneously.
2, remote work
GPRS not only has a long working distance, but also can perform two-wayoperation of the system, which is very suitable for some applications such asremote device operation and remote device upgrade.
3, low cost
Because the GPRS network covers most areas, there is basically no blind area,so there is no need to establish a communication network separately. Only thedevice needs to be installed and inserted into the SIM card, so that networkcommunication can be performed.
4, a wide range of applications

GPRS can be usedfor communication in complex urban environments, remote mountainous areas, andultra-long-distance inter-regional areas. Due to its wide coverage, unlimitedgeographical area, and unlimited capacity expansion, it is ideal for buildinginformation acquisition systems. .
5, fast landing
Fixed dialing mode requires at least 8-10s because of the need to dial, verify,log in to the server, etc., and GPRS will immediately apply to enter the GPRSnetwork when booting, and only need to transfer data from the link to theremote server. — 3s of time.
6, high data rate
According to different coding schemes (CS-1~CS-4), GPRS has a data rate of9.05Kb/s, 13.4Kb/s, 15.6Kb/s, and 21.4Kb/s. If a set of data is transmittedusing an 8 hour channel, the theoretical maximum physical frame data ratetransmitted over the air can be 21.4*8=171.2 Kbps. However, because of the needto use error correction coding and anti-interference problems in practicalapplications. Therefore, the general GPRS module adopts two coding modes ofCS-1 and CS-2, and the operator provides up to four time slots for thecustomer, but the maximum speed can still reach 13.4*4=53.6Kbps, and theaverage transmission rate can also reach about 40Kbps. .
7, low communication costs
The GPRS module uses a SIM card to charge according to the traffic or monthlysubscription, and can directly transmit data with the Internet. So don't worryabout excessive communication costs