thumbnail|EDGE sign shown in notification bar on an Android-based smartphone
Enhanced Data rates for GSM Evolution (EDGE), also known as 2.75G and under various other names, is a 2G digital mobile phone technology for packet switched data transmission. It is part of the GSM family and represents an upgrade to General Packet Radio Service (GPRS), also known as "2.5G". EDGE is standardized by the 3GPP and offers speeds close to 3G technology, hence the name "2.75G".
EDGE was deployed on GSM networks beginning in 2003 – initially by Cingular (now AT&T) in the United States. It could be readily deployed on existing GSM and GPRS cellular equipment, making it an easier upgrade for cellular companies compared to the UMTS 3G technology that required significant changes. Through the introduction of sophisticated methods of coding and transmitting data, EDGE delivers higher bit-rates per radio channel, resulting in a threefold increase in capacity and performance compared with an ordinary GSM/GPRS connection - originally a max speed of 384 kbit/s. Later, Evolved EDGE was developed as an enhanced standard providing even more reduced latency and more than double performance, with a peak bit-rate of up to 1 Mbit/s.
Name and definition
Enhanced Data rates for GSM Evolution is the common full name of the EDGE standard. Other names include: Enhanced GPRS (EGPRS), IMT Single Carrier (IMT-SC), and Enhanced Data rates for Global Evolution.
Although described as "2.75G" by the 3GPP body, EDGE is part of International Telecommunication Union (ITU)'s 3G definition. It is also recognized as part of the International Mobile Telecommunications - 2000 (IMT-2000) standard for 3G.
Technology
thumb|Cellular network standards and generation timeline
EDGE/EGPRS is implemented as a bolt-on enhancement for 2.5G GSM/GPRS networks, making it easier for existing GSM carriers to upgrade to it. EDGE is a superset to GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrade. EDGE requires no hardware or software changes to be made in GSM core networks. EDGE-compatible transceiver units must be installed and the base station subsystem needs to be upgraded to support EDGE. If the operator already has this in place, which is often the case today, the network can be upgraded to EDGE by activating an optional software feature. Today EDGE is supported by all major chip vendors for both GSM and WCDMA/HSPA.
Transmission techniques
In addition to Gaussian minimum-shift keying (GMSK), EDGE uses higher-order PSK/8 phase-shift keying (8PSK) for the upper five of its nine modulation and coding schemes. EDGE produces a 3-bit 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) according 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.
EDGE can carry a bandwidth up to 236 kbit/s (with end-to-end latency of less than 150 ms) for 4 timeslots (theoretical maximum is 473.6 kbit/s for 8 timeslots) in packet mode. This means it can handle four times as much traffic as standard GPRS. EDGE meets the International Telecommunication Union's requirement for a 3G network, and has been accepted by the ITU as part of the IMT-2000 family of 3G standards. In GPRS, the Coding Schemes CS-1 to CS-4 specify the number of parity bits generated by the cyclic code and the puncturing rate of the convolutional code. a radio block consists of MAC header, RLC header, RLC data unit and spare bits. The RLC data unit represents the payload, the rest is overhead. The radio block is coded by the convolutional code specified for a particular Coding Scheme, which yields the same PHY layer data rate for all Coding Schemes.<br />(kbit/s/slot)
! Bitrate excluding RLC/MAC overhead<br />(kbit/s/slot)
! Modulation
! Code rate
|- align=center
| CS-1
| 9.20
| 8.00
| GMSK
| 1/2
|- align=center
| CS-2
| 13.55
| 12.00
| GMSK
| ≈2/3
|- align=center
| CS-3
| 15.75
| 14.40
| GMSK
| ≈3/4
|- align=center
| CS-4
| 21.55
| 20.00
| GMSK
| 1
|}
{| class="wikitable" align=center style="float:left; margin:0.26em 0.8em; margin-right:0.2em; margin-left:0px;"
! EDGE modulation and coding <br />scheme (MCS)
! Bitrate including RLC/MAC overhead<br />(kbit/s/slot)
! Bitrate excluding RLC/MAC overhead<br />(kbit/s/slot)
! Modulation
! Data<br />code rate
! Header<br />code rate
|- align=center
| MCS-1
| 9.20
| 8.00
| GMSK
| ≈0.53
| ≈0.53
|- align=center
| MCS-2
| 11.60
| 10.40
| GMSK
| ≈0.66
| ≈0.53
|- align=center
| MCS-3
| 15.20
| 14.80
| GMSK
| ≈0.85
| ≈0.53
|- align=center
| MCS-4
| 18.00
| 16.80
| GMSK
| 1
| ≈0.53
|- align=center
| MCS-5
| 22.80
| 21.60
| 8PSK
| ≈0.37
| 1/3
|- align=center
| MCS-6
| 30.00
| 28.80
| 8PSK
| ≈0.49
| 1/3
|- align=center
| MCS-7
| 45.20
| 44.00
| 8PSK
| ≈0.76
| ≈0.39
|- align=center
| MCS-8
| 54.80
| 53.60
| 8PSK
| ≈0.92
| ≈0.39
|- align=center
| MCS-9
| 59.60
| 58.40
| 8PSK
| 1
| ≈0.39
|}
Deployment
The first EDGE network was deployed by Cingular (now AT&T) in the United States T-Mobile US deployed their EDGE network in September 2005. In Canada, Rogers Wireless deployed their EDGE network in 2004. In Malaysia, DiGi launched EDGE beginning in May 2004 initially only in the Klang Valley.
In Europe, TeliaSonera in Finland rolled out EDGE in April 2004. Orange began trialling EDGE in France in April 2005 before a consumer rollout later that year. Bouygues Telecom completed its national deployment of EDGE in the country in 2005, strategically focusing on EDGE which is cheaper to deploy compared to 3G networks. Telfort was the first network in the Netherlands to roll out EDGE having done so by May 2005. Orange launched the UK's first EDGE network in February 2006.
The Global Mobile Suppliers Association reported in 2008 that EDGE networks have been launched in 147 countries around the world.
Evolved EDGE
Evolved EDGE, also called EDGE Evolution and 2.875G, is a bolt-on extension to the GSM mobile telephony standard, which improves on EDGE in a number of ways. Latencies are reduced by lowering the Transmission Time Interval by half (from 20 ms to 10 ms). Bit rates are increased up to 1 Mbit/s peak bandwidth and latencies down to 80 ms using dual carrier, higher symbol rate and higher-order modulation (32QAM and 16QAM instead of 8PSK), and turbo codes to improve error correction. This results in real world downlink speeds of up to 600 kbit/s. Further the signal quality is improved using dual antennas improving average bit-rates and spectrum efficiency.
The main intention of increasing the existing EDGE throughput is that many operators would like to upgrade their existing infrastructure rather than invest on new network infrastructure. Mobile operators have invested billions in GSM networks, many of which are already capable of supporting EDGE data speeds up to 236.8 kbit/s. With a software upgrade and a new device compliant with Evolved EDGE (like an Evolved EDGE smartphone) for the user, these data rates can be boosted to speeds approaching 1 Mbit/s (i.e. 98.6 kbit/s per timeslot for 32QAM). Many service providers may not invest in a completely new technology like 3G networks.
Considerable research and development happened throughout the world for this new technology. A successful trial by Nokia Siemens and "one of China's leading operators" was achieved in a live environment.
Compact-EDGE
A variant, so called Compact-EDGE, was developed for use in a portion of Digital AMPS network spectrum.
Networks
The Global mobile Suppliers Association (GSA) states that, as of May 2013, there were 604 GSM/EDGE networks in 213 countries, from a total of 606 mobile network operator commitments in 213 countries.
See also
- Broadband Internet access
- CDMA2000
- Evolution-Data Optimized
- List of device bandwidths
- Mobile broadband
- Spectral efficiency comparison table
- UMTS
- WiDEN
- Wi-Fi
- Comparison of mobile phone standards including LTE
- Comparison of wireless data standards including WiMAX and HSPA+
References
External links
- The Global mobile Suppliers Association
- Evolved EDGE as an alternative to 3G
- A technical document by the 3G Americas association
- An opinion on evolved EDGE by Martin Sauter
- An EDGE Evolution report by Visant Strategies