GPRS or General Packet Radio Service is a technology that extends the existing GSM network. With this technology in a more efficient, faster and cheaper way mobile data sent and received. Although we speak of GPRS networks is not a new GPRS network.
With GPRS users are always online. This means that they have a constant connection to the Internet or corporate network and therefore only once need to call every day to be online. They thereby not pay for the time they logged in, but are judged on the amount of data they download or send. The user holds the connection also only occupied at times when there is actual use made thereof. Thus, the capacity is better utilized and more data can be exchanged simultaneously.
Changes in the network
The existing GSM network is expanded to include an SGSN (Serving GPRS Support Node), which ensures that the users may be mobile and able to get access to the network, and a GGSN (Gateway GPRS Support Node), which ensures a connection with Internet or intranet . This makes sending and receiving packet data possible.
Devices
There are 3 classes of devices:
- Class A: both call and send data as possible
- Class B: Automatic sequential switching between call and send data is possible, but not both simultaneously
- Class C: alternative use (or dates, or call), or only GPRS.
The last class is most prevalent on PC Cards for laptops; Class B is for most appliances.
Data Rate
GPRS can invade multiple timeslots, asymmetric allocation is also possible (eg : more channels are selected in downlink than in uplink).
Use is made of a custom coding, here sorted from heavy to no error correction:
- CS1: 9 kb/s
- CS2: 13.4 kb/s
- CS3: 15.6 kb/s
- CS4: 21.4 kb/s
Limitations
- Since the network is not all timeslots will assign one user, the theoretical data rate is not achieved.
- It is the same modulation technique used in GSM, specifically focusing on speech and battery consumption by only a limited ability to use. In addition, this modulation technique does not allow sending more than one bit per second.
- Delays can occur.
Successors
- EDGE : This uses the same network as GSM (and GPRS), but uses a different modulation technique allowing higher speeds are possible. Sometimes called sometimes 2.5G GPRS (2G is the GSM standard and 3G UMTS).
- UMTS : uses a new network architecture, both for voice and data. Also called 3G (third generation) called.
- HSDPA : uses the same network architecture as that of UMTS .