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Enhanced Data Rates for GSM Evolution (EDGE) is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2.5G (a.k.a.GPRS) networks.
This technology is working in TDMA and GSM networks.
EDGE uses the same spectrum allocated for GSM850, GSM900, GSM1800 and GSM1900 operation.
In addition to GMSK (Gaussian minimum-shift keying) EDGE uses 8PSK (8 Phase Shift Keying) for its upper five of the nine modulation and coding schemes. EDGE is producing a 3bit word for every change in carrier phase. This effectively triples the gross data rate offered by GSM. EDGE, like GPRS, uses a rate adaptation algorithm that adapts the modulation and coding scheme (MCS) used to the quality of the radio channel, and thus the bit rate and robustness of data transmission. It introduces a new technology not found in GPRS, Incremental Redundancy, which, instead of retransmitting disturbed packets, sends more redundancy information to be combined in the receiver. This increases the probability of correct decoding.
It can carry data speeds up to 384 kbit/s in packet mode and will therefore meet the International Telecommunications Union's requirement for a 3G network, and has been accepted by the ITU as part of the IMT-2000 family of 3G standards. It also enhances the circuit data mode called HSCSD, increasing the data rate of this service also.
EDGE is being introduced into GSM networks around the world in 2003, initially in North America.
As of 2004, EDGE is more actively supported by GSM operators in North America than anywhere else in the world because GSM/GPRS has a strong competitor: CDMA2000. Most other GSM operators view UMTS as the ultimate upgrade path and either plan to skip EDGE altogether or use it outside the UMTS coverage area. However, the high cost and slow uptake of UMTS (as demonstrated by the upstart network 3) have made some western European GSM operators reevaluate EDGE as an interim upgrade.
Although EDGE requires no hardware changes to be made in GSM core networks, base stations must be modified. An EDGE compatible tranceiver unit must be installed and base station system needs to be upgraded to support EDGE. New mobile terminal hardware and software is also required to decode/encode using the new shift keying scheme.
EDGE provides Enhanced GPRS (EGPRS) which can be used for any packet switched applications such as an Internet connection. High-speed data applications such as video services and other multimedia benefit of EGPRS' increased data capacity.
See also: UMTS
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