gprs software or General Packet Radio Service is a packet switched technology, based on GSM. The radio and network resources of gprs software are only accessed when data actually needs to be transmitted between the gprs software mobile user and the gprs software network. This data is divided into packets and is then transferred via the radio and core gprs software network. Between alternating transmissions, no gprs software network resources need to be allocated. gprs software offers up to 115 kbps, depending on the network availability, channel coding scheme and terminal capability. This increase in speed in gprs software with respect to GSM is achieved by using more than one timeslot of the TDMA frame. Due to the packet switched characteristics of gprs software the allocation of the available timeslots may vary from one instant to the next (e.g. it may have 8 timeslots at one time and 4 later on).

The General Packet Radio Service (GPRS) is a new value added service that allows information to be sent and received across a mobile telephone network. It supplements today's Circuit wireless Switched Data and Short Message Service.

Timeslot building requires new functionality on the mobile side. gprs software needs a Serving gprs software support node (SGSN), a Gateway gprs software support node (GGSN) and a charging gateway function to support packet switched transactions. The packet switched traffic is separated from the circuit switched traffic at the BSC/PCU and diverted to the gprs software core network. To support point-to-multipoint features, a point-to-multipoint Service Center (PTM-SC) needs also to be added.

Depending on the environmental radio conditions, one of the four coding schemes (CS1, CS2, CS3, CS4) can be selected. CS1 and CS2 offer good error detection and correction with low throughput; in the first step of gprs software only these two techniques may be used. CS3 and CS4 provide higher throughputs but have little or no error correction capabilities.

Table 1 shows the different data rates that can be achieved with the different coding techniques.

Because gprs software is packet switched traffic, new protocols and channel types are required. In gprs software the mobile device is permanently attached to the network, providing a virtual connection without cost and data transfer (GPRS-Attach). gprs software-Attach procedure is executed whenever a gprs software enabled mobile station is switched on and needs to inform the network about its presence.

The two peers of a gprs software attach procedure are the mobile station (MS) and the Serving gprs software Support Node (SGSN). Depending on the availability of the packet Common Control Channel (PCCCH), the gprs software-Attach procedure may be executed on Circuit Common Control Channel (CCCCH).

Figure 1 shows the gprs software system architecture, indicating new functionality required for phase2+ operation.

Figure 1. GPRS Software system architecture

Layer 1. Radio gprs software. This layer includes the following GSM phase2+ ETSI standards:

ˇGSM 05.02 Access & Multiple Multiplexing.
ˇGSM 05.03 Interleaving Code/Decoder Channel.
ˇGSM 05.04 Demodulator and Modulator.
ˇGSM 05.05 Receiver and Transmitter.
ˇGSM 05.10 Synchronization.

Layer 1.Vocoders gprs software. This layer includes the following GSM phase2+ ETSI standards:

ˇGSM 06.10 Full rate speech transcoding.
ˇGSM 06.20 Half rate speech transcoding.
ˇGSM 06.60 Enhanced Full rate speech transcoding.
ˇGSM 06.90 Adaptive multi-rate speech transcoding.
ˇGSM 06.93 Discontinuous transmission for Adaptive Multi-rate.

Layer 2 & 3 GSM phase 2+ ETSI standards:

ˇGSM 03.09 Hand-over.
ˇGSM 03.22 Link control.
ˇGSM 04.04 PROTOCOLS Layer 1.
ˇGSM 04.05 PROTOCOLS Layer 2.
ˇGSM 04.06 PROTOCOLS Layer 2.
ˇGSM 04.07 PROTOCOLS Layer 3.
ˇGSM 04.08 PROTOCOLS Layer 3.
ˇGSM 05.08 Power control.

EGPRS (also call EDGE) is an enhanced version of gprs software, that uses a different modulation technique, 8 PSK, that has a spectral efficiency of 3 bits/s/Hz. gprs software uses GMSK, with a spectral efficiency of 1 bit/s/Hz.

GPRS Software will provide an important boost to mobile data usage, because of its flexible feature set, its latency, efficiency and speed.

The following text, in the links below, provides VOCAL datasheet as a source of background information about gprs software.

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VOCAL Technologies, Ltd. modem software libraries include a complete range of ETSI / ITU / IEEE compliant modulations, optimized for execution on ANSI C and leading DSP architectures (ADI, AMD-Alchemy, ARM, CEVA, LSI Logic ZSP, MIPS and TI). This software is modular and can be executed as a single task under a variety of operating systems or it can execute standalone with its own kernel.

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