GPRS General Packet Radio Service Tutorial Includes:
GPRS basics Network architecture Mobile / multislot classes Radio interface Coding Channels: physical, logical, control GPRS protocol stack Operational states
GPRS mobiles are able to support data transmission as well as voice. GPRS mobiles are available with a variety of levels of operation. These are often defined by defining them as a particular GPRS class. These GPRS classes indicate the level of service they are able to provide.
In many respects many GPRS mobile phones may not look different to ordinary GSM phones, but they are able to offer a level of data service that cannot be provided by a standard GSM phone. Some GPRS phones may even offer a keyboard for emails, etc.
GPRS performance categories
Not all GPRS mobiles are designed to offer the same levels of service. As a result they are split into three basic categories according to their capabilities in terms of the ability to connect to GSM and GPRS facilities:
- Class A: - This class describes mobile phones that can be connected to both GPRS and GSM services at the same time.
- Class B: - These mobiles can be attached to both GPRS and GSM services but they can be used on only one service at a time. A Class B mobile can make or receive a voice call, or send and or receive a SMS message during a GPRS connection. During voice calls or texting the GPRS service is suspended but it is re-established when the voice call or SMS session is complete.
- Class C: - This classification covers phones that can be attached to either GPRS or GSM services but user needs to switch manually between the two different types.
GPRS multislot classes
GPRS mobiles are also categorized by the data rates they can support. Within GSM there are eight time slots that can be used to provide TDMA, allowing multiple mobiles onto a single RF signal carrier. Using GPRS it is possible to use more than one slot to enable much higher data rates to be achieved when these are available. To quantify the capability of different mobiles there are a number of different GPRS multislot classes that are defined.
Sometimes these may be referred to as speed classes. The different speed classes of the mobiles are dependent upon the number of slots that can be used in either direction.
GPRS multislot class one mobiles are able to send and receive in one slot in either direction, i.e. uplink and downlink, and class 29 mobiles are able to send and receive in all eight slots. The classes within these two limits are able to support sending and receiving in different combinations of uplink and downlink slots.
|GPRS MUltislot Classes|
|Maximum Number of Slots|
|GPRS Multislot Class||Receive||Transmit||Sum||Duplex Type|
1) The multislot classes also differ in the minimum number of time-slots, for example between uplink and downlink.
2) The figure referred to as sum, indicates the maximum total number of slots in the uplink and downlink that are available at time.
3) Duplex type 1 is semi-duplex and type 2 is full duplex.
GPRS mobile phones are available with a very wide range of different performance levels. These are defined by the different GPRS categories and GPRS classes. In particular the GPRS class will be seen mentioned in the literature and this defines the maximum data rates that can be achieved under ideal conditions.
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