General Packet Radio Service

By: Ian Ball

HOW GPRS FUNCTIONS:

The GPRS functions in the packet switch system, as in many users will use a single common channel for the transfer of data. That is a set of users will share a bandwidth for the intermittent transmission such as web browsing, sending and receiving of e-mails. The GPRS originally supported the Internet Protocol connections. However, now it is also being used for the transmission purposes in mobile phone standards. The data transfer in GPRS is billed per kilobyte of data transferred.

Based on the usage of GPRS, the devices are classified into different types or classes:

?Type 1: These devices can be connected to GSM and GPRS and they function by allowing both the services. This requires two radios, as there are two frequencies transmitted.

?Type 2: These devices can be connected to GSM and GPRS. However, only one of the services can be used at a time. Most of the mobile phones are designed in this way only.

?Type 3: These devices can be connected to GSM and GPRS, but the connection must be switched manually. Therefore, even these devices can use only one of the services at a time.

During a session of data transfer, the user will be assigned a pair of frequency channels. The uplink and the downlink channel. These are combined with many such frequency channel pairs to form a packaged communication mode. Each packet will have its own time length, depending on the time slot on GSM. The speed of GPRS depends on the number of time slots assigned. Based on this the devices are classified as follows:

?Class 2: Minimum GPRS set up

?Class 4: Modest GPRS set up. This will be a little faster than Class 2.

?Class 6: Modest GPRS set up. This is better than the Class 4.

?Class 8: Better set up. This is will be faster than classes 4 and 6.

?Class 10: Better set up. This is faster than Class 8. It is seen in cell phones and PC cards.

?Class 12: Best set up. Seen only in high end PC cards.

The function of GPRS is packet based. The particular phone or system will have many IP addresses allocated. The GPRS will store the addresses and will forward them to the phone during the cell handover.

The GPRS complements the GSM by providing many services such as:

?Push to talk
?Multimedia Messaging Service
?Short Messaging Service
?Instant Messaging and many more.

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