An EDGE over GSM

A new faster version of GSM that can challenge existing 3G technologies

Friday, February 07, 2003

We have seen how GSM works. Now let’s look at EDGE (Enhanced Data GSM Environment) technology that is a ‘faster version’ of GSM wireless service and has been designed to deliver data up to 384 kbps. For this reason it is also called ‘GSM384.’ Such speed enhancement is obtained by changing the type of modulation used. Edge also connects to GPRS systems and supports multimedia and broadband applications on your mobile. It makes use of the TDMA (Time Division Multiple Access) frame structure, which it has inherited from the GSM network, and at the same time builds upon GPRS and HSCSD (High Speed Circuit Switched Data).

EDGE technology 
Edge does not ask for any drastic changes in the current GSM networks. All it asks for are upgrades for service nodes used for packet switching that exist in GPRS networks. These upgrades include the GPRS (Gateway GPRS service node) and the SGSN (Serving GPRS service node). The GGSN provides connectivity from the EDGE network to packet switched networks like X.25, IP and other GPRS networks. The SGSN on the other hand connects the EDGE network to the mobile stations.

Now all that needs to be done after these upgrades is an addition of an EDGE transceiver to each cell and a remote software upgrade to the base stations. After this, EDGE co-exists with the existing GSM traffic and shifts the entire network to the EDGE mode automatically.

High speed
A GPRS uses the GMSK (Gaussian Minimum Shift Keying) modulation technique for transmitting data over the network.

Though this modulation technique gives good transfer speeds to the GPRS, it is not quite the same for EDGE. EDGE uses a different modulation technique called 8PSK (Eight Phase Shift Keying) that can offer a transmission rate of 48 kbps per channel in good conditions. As compared to the GPRS, which gives a transfer rate of 14 kbps or GSM that gives 9.6 kbps with 8PSK, Edge certainly gives faster transfer rates. Moreover, by using multiple channels, Edge can harness the power to transfer up to 384Kbps.

EDGE has already become quite popular in the US while Europe still has to catch up on this technology. Though still in a developing phase, it certainly has an edge over existing 3G technologies.

Varun Sharma

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