As its name suggests, EDGE (Enhanced Data rates for Global Evolution) is an enhancement of the GSMTM radio access technology to provide faster bit rates for data applications, both circuit- and packet-switched. As an enhancement of the existing GSM physical layer, EDGE is realized via modifications of the existing layer 1 specifications on the 3GPP website rather than by separate, stand-alone specifications.
Other than providing improved data rates, EDGE is transparent to the service offering at the upper layers, but is an enabler for High Speed Circuit Switched Data (HSCSD) and Enhanced GPRS (EGPRS). By way of illustration, the General Packet Radio Service (GPRS) can offer a data rate of 115 kbit/s whereas EDGE can increase this to 384 kbit/s. This is comparable with the rate for early implementations of Wideband Code Division Multiple Access (W-CDMA), leading some parties to consider EDGE as a 3G technology rather than 2G (a capability of 384 kbit/s allows EDGE systems to meet the ITU's IMT-2000 requirements). However, EDGE is generally viewed as a bridge between the two generations: a sort of 2.5G.
New modulation technique
The increased data rate is accomplished by a new modulation technique (8PSK as opposed to GSM/GPRS's GMSK, yielding a three-fold increase in bit rate for an identical symbol rate) coupled with new channel coding, resulting in improved spectral efficiency. This is important, because it allows EDGE to be introduced piecemeal into existing GSM networks without disrupting the frequency reuse plan of the existing deployment.
In fact, to cater for the potentially increased sensitivity to noise in marginal coverage areas, EDGE uses a combination of 8PSK and GMSK, to give a balanced improvement in bit rate under virtually all radio conditions. The four coding schemes of GPRS are increased to nine in EDGE, and new segmentation techniques can radically improve throughput by permitting the coding scheme to be changed on the fly in case of retransmission of a segment in rapidly changing radio conditions. In addition, the packet window size increased to 1024 compared with the 64 for GPRS, resulting in more robust transmission and reception.
The implementation of EDGE is summarized in 3GPPTM TR10.59 (later 50.058) - essentially a catalogue of Change Requests which introduced EDGE functionality into the existing specifications, for Release 98. TR 10.58 / 50.058 has not been transposed into an official ETSI publication because it does not meet the necessary criteria. It remains, however, a very useful reference document.
A variant of EDGE, called 'EDGE Compact', permits deployment in less than 1 MHz of spectrum.
EDGE is compatible with the North American cellular system, ANSI IS136.
The following is a list of the latest published ETSI standards on EDGE.
A full list of related standards in the public domain is accessible via the ETSI standards search. Via this interface you can also subscribe for alerts on updates of ETSI standards.
For work in progress see the ETSI Work Programme on the Portal.
|Standard No.||Standard title.|
|EN 301 489-50||Electromagnetic compatibility and Radio spectrum Matters (ERM); ElectroMagnetic Compatibility (EMC) standard for radio equipment and services; Part 50: Specific conditions for Cellular Communication Base Station (BS), repeater and ancillary equipment|
|EN 301 908-8||Electromagnetic compatibility and Radio spectrum Matters (ERM); Base Stations (BS) and User Equipment (UE) for IMT-2000 Third-Generation cellular networks; Part 8: Harmonized EN for IMT-2000, TDMA Single-Carrier (UWC 136) (UE) covering essential requirements of article 3.2 of the R&TTE Directive|
|EN 301 908-9||Electromagnetic compatibility and Radio spectrum Matters (ERM); Base Stations (BS) and User Equipment (UE) for IMT-2000 Third-Generation cellular networks; Part 9: Harmonized EN for IMT-2000, TDMA Single-Carrier (UWC 136) (BS) covering essential requirements of article 3.2 of the R&TTE Directive|
|EN 301 908-18||IMT cellular networks; Harmonised Standard covering the essential requirements of article 3.2 of the Directive 2014/53/EU; Part 18: E-UTRA, UTRA and GSM/EDGE Multi-Standard Radio (MSR) Base Station (BS)|