SEMINAR ON WHAT IS GPRS? 2004-2006 IN MSC IST YR

What is GPRS?

GPRS (General Packet Radio Service) is a step between GSM and 3G cellular networks. GPRS offers faster data transmission via a GSM network within a range 9.6Kbits to 115Kbits. This new technology makes it possible for users to make telephone calls and transmit data at the same time. (For example, if you have a mobile phone using GPRS, you will be able to simultaneously make calls and receive e-mail massages.) The main benefits of GPRS are that it reserves radio resources only when there is data to send and it reduces reliance on traditional circuit-switched network elements with GPRS, an IP data transmission protocol, which is characteristic of computer networks, is being introduced to GSM. IP is a data transmission protocol, which is used in Internet, the largest computer network in the world today.

Main features of GPRS

Before introduction of GPRS, the radio capacity was used for calls and data transmission within the GSM network in a rather inefficient way. For data transmission the entire channel was occupied and was thus insufficiently used. With the GPRS technology, the channel is used more efficiently owing to the possibility of more than one user sharing the same channel. GPRS telephones user several channels for data transfer thus facilitating greater transfer speeds. The GPRS infrastructure and mobile phones support a data transmission speed of up to 13.4Kbits per channel.

GPRS signaling and data traffic do not travel through the GSM network. The GSM network is only used for table look up, in the Location Register (HLR and VLR) databases, to obtain GPRS user profile data.

GPRS Telephones

Owing to the fact that more than one channel is used for downlink; the GPRS

mobile phones make possible greater data transmission speeds. There are several types of phones with regard to the number of channels they use for data transmission... The GPRS mobile phones can be classified into the following three classes in terms of the possibility of simultaneous calls (via GSM) and data transmission (via GPRS)...

Conclusions

GPRS, a 2.5G system, is poised to take off this year in popularity. Building on the GSM network, it will provide the much needed packet data services to most areas of the world. Nuntius can help make this a reality with its GPRS solutions. Nuntius has expertise in the mobile handset technologies such as RF interfaces, Physical Link Layer (PLL), Media Access Control (MAC), Radio Link Control (RLC), Link Layer Control (LLC), Sub network Dependent Convergence Protocol (SNDCP), and Radio Resource Management (RRM). Below is a list of some of the basic characteristics of GPRS. For more information, contact Nuntius Systems, Inc.

Data rate: Maximum of 171.2 kbps

Channel coding

Ø      Outer block coding

Ø      Inner Convolution coding

Ø      Interleaving scheme for error bursts

Modulation

Gaussian Minimum Shift Keying GMSK

Multiple Accesses

Combination of TDMA & FDMA

Transmit Frequency Bands

Mobile Station	Uplink	Reverse ch. 890-915 MHz
Base Station	Downlink	Forward ch. 935-960 MHz

                                     

Duplex separation     45 MHz

RF carrier spacing     200 kHz

Total number of RF Duplex channels     124

Transmission

Ø      Channel coder

Ø      Block encoder

Ø      Pre-coding of Uplink Status Flag (USF)

Ø      Add Tail bits

Ø      Convolutional encoder

Ø      Puncturing

Ø       

Ø      Reception

 

GMSK Demodulator

Ø      Viterbi equalizer

Ø      Deinterleaver

Ø      Viterbi decoding

GPRS - Standard Library Functions

The following is a list of the standard library functions to perform the various aspects of GPRS. These functions can be implemented in a DSP or the ARM RISC architecture. In general, the layer 1 functions are usually implemented in the DSP while upper layer protocols such as SNDCP are implemented in the ARM RISC. The channel models are used for simulating the channel operating environment and are not a function that would be implemented in a mobile handset or base station.

Channel coders	Interleaver / deinterleaver
Block encoder Fire coder Precoding of uplink status flags Convolutional coder (1/2, 2/3 and 3/4) Puncturing	Interleaver of depth 4 / deinterleaver
Channel models	Modulator / demodulator
Rayleigh distribution Rice distribution Propogation models for urban and rural areas	GMSK modulation / demodulation
Channel decoder
Viterbi decoder

The Future

Currently GPRS is in its infancy and both the Motorola T260 triple band phone and the Trium Mondo Personal Digital Organiser support WAP over GPRS. Later this year, Mobile Data over GPRS will also be available offering 2 to 3 times faster speeds for traditional web pages, not just Mobile Internet WAP pages.

Availability

Motorola have launched the first commercially available GPRS mobile with the Motorola T260 which is also a triple band phone allowing it's use not only in Europe and Asia but also in the USA and Canada too. Trium have now also launched the first GPRS personal digital assistant. We'll have more details available on this shortly. The GPRS availability depends on the network, please contact your network operator or service provider for more information. The GPRS functionality is product dependent, for more information please contact you’re nearest Nokia retailer.