Sony Ericsson manual Using Gprs in the T226

T226 White Paper

July 2003 (Rev C)

1 GSM 9,600 bps

9,600/14,400

14,400, 19,200 or 28,800 bps (HSCSD)

9,600/14,400

9,600/14,400

9,050/13,400/
15,600/21,400
2	GPRS
9,050/13,400/	9,050, 13,400,
	15,600, 18,100,
15,600/21,400
	21,400, 26,800,
9,050/13,400/	27,150, 31,200
15,600/21,400	40,200, 42,800,

46,800 or 64,200 bps

9,050/13,400/

15,600/21,400

Figure 4 A comparison between GSM and GPRS

1.A normal GSM call uses only one of eight repeat- ing time slots in the GSM channel, giving a data speed of 9,600 bps. The T226 supports a more efficient cod- ing scheme, giving data speeds of up to 14,400 bps (with necessary network support). Furthermore, High Speed Circuit Switched Data (HSCSD) adds the possi- bility of using two time slots for receiving data, increasing the data speed to as much as 28,800 bps (network dependent).

2.In GPRS, data is sent in packets, with up to three time slots being combined to provide the necessary bandwidth. The T226 is prepared to support 3+1 time slots (three slots for receiving data and one slot for transmitting data), giving speeds of up to 64,200 bps for receiving data, depending on coding scheme.

Using GPRS in the T226

Instead of occupying an entire voice channel for the duration of a data session, the T226 sends/receives data in small packets, as needed, much like IP on the Internet. Because of this, the T226 maintains a constant online connection. Its data transmission abilities are summoned by the application in use on an as-needed basis.

The GPRS specification includes four coding schemes

–CS1, CS2, CS3 and CS4 – that allow data speeds of 9,050 bps, 13,400 bps, 15,600 bps and 21,400 bps respectively using one time slot. The T226 works with all four coding schemes, but data speed will naturally vary according to network configuration. At the moment, CS3 and CS4 are not supported in any live network, i.e., present speed is limited to 40,200 bps using three time slots.

The GSM system limits the ability to use all eight time slots, so the T226 uses up to three time slots for

receiving data, and one slot for transmitting (3+1). This means that for CS4, the speed for receiving data is up to 64,200 bps and up to 21,400 bps for sending data.

Information about the identity of the phone and the characteristics of the connection are described in the PDP (Packet Data Protocol) context. This information is stored both in the phone and in the mobile network, so that each phone is identified and “visible” to the system.

Using GPRS with the T226 has several advantages, for example:

•All connection settings can be managed by using the data connections feature.

•High speed

Gain access automatically to increased band- width when downloading images, etc.

•Cost efficient

Use transmission capacity only when needed,

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