Enhanced Data rates for GSM Evolution (EDGE) (also known as Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC)) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE is considered a 3G radio technology and is part of ITU's 3G definition.EDGE was deployed on GSM networks beginning in 2003— initially by Cingular (now AT&T) in the United States.
EDGE is standardized by 3GPP as part of the GSM family, and it is an upgrade that provides more than three-fold increase in both the capacity and performance of GSM/GPRS networks. It does this by introducing sophisticated methods of coding and transmitting data, delivering higher bit-rates per radio channel.
EDGE can be used for any packet switched application, such as an Internet connection. EDGE-delivered data services create a broadband internet-like experience for the mobile phone user. High-speed data applications such as video services and other multimedia benefit from EGPRS' increased data capacity.
Evolved EDGE continues in Release 7 of the 3GPP standard providing reduced latency and more than doubled performance e.g. to complement High-Speed Packet Access (HSPA). Peak bit-rates of up to 1Mbit/s and typical bit-rates of 400kbit/s can be expected.
Technology:
EDGE/EGPRS is implemented as a bolt-on enhancement for 2G and 2.5G GSM and GPRS networks, making it easier for existing GSM carriers to upgrade to it. EDGE/EGPRS 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 data speeds up to 236.8 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 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. EDGE is part of ITU's 3G definition and is considered a 3G radio technology.
EDGE Evolution:
EDGE Evolution 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 speed and latencies down to 800 ms using dual carriers, higher symbol rate and higher-order modulation (32QAM and 16QAM instead of 8-PSK), and turbo codes to improve error correction. And finally signal quality is improved using dual antennas improving average bit-rates and spectrum efficiency. EDGE Evolution can be gradually introduced as software upgrades, taking advantage of the installed base. With EDGE Evolution, end-users will be able to experience mobile internet connections corresponding to a 500 kbit/s ADSL service.
EDGE( Enhanced Data Rates for GSM Evolution)
HSPDA - the next step for 3G
With 3G networks spreading throughout the globe, consumers are just now beginning to experience the true capabilities of 3G wireless services. Already, some fear that demands for high-speed data access will exceed the capability of today's UMTS networks. Fortunately, the wireless industry already has plans in place for enhanced data networks.
Among the next-generation contenders in the ring are Flarion's Flash OFDM (F-OFDM), WiMAX (IEEE802.16e) and CDMA2000 1XEV-DO. But it's high-speed downlink packet access, or HSDPA, that enables a smooth, cost-efficient upgrade to existing W-CDMA networks at minimal cost.
HSDPA's incremental UMTS network upgrade aims to increase user peak data rates and quality-of-service and improve spectral efficiency - much like EDGE and 1XRTT have done for 2G. Although UMTS enables streaming video, broadband Internet access and video conferencing, HSDPA offers peak downlink data rates of up to 14 Mbps - dramatically more than the 384 kbps that is typical of today's UMTS and the highest data rate of any available mobile WAN technology.
HSPDA works by moving important processing functions closer to the air interface. Although current UMTS networks perform network scheduling and retransmission in the radio network controller, HSDPA moves these functions to the base station (called Node B in UMTS systems), allowing scheduling priority to take account of channel quality and terminal capabilities. Retransmission also benefits from hybrid automatic retransmission request in which retransmissions are combined with prior signal transmissions to improve overall reception. HSDPA adds a channel-sharing mechanism that allows several users to share the high-speed air interface channel and other technological advances such as adaptive modulation and coding, quadrature amplitude modulation and channel quality feedback. These enhancements allow HSDPA to roughly double the total throughput capacity of a network.
For consumers, that translates into shorter service response times, fewer waits and faster connections. Wireless users can talk on the phone while simultaneously downloading packet data. Most important, they can use their wireless handsets to download Web pages, audio or video at speeds well above the performance they are accustomed to with landline-based DSL or even cable Internet connections.
What's good for the consumer ultimately is good for the operator, provided the costs and barriers to deployment are not too great. HSDPA significantly enhances W-CDMA with little hardware investment. It operates in 5 MHz channels and is backward-compatible with current W-CDMA networks. This allows network operators to introduce greater capacity and higher data speeds on the same carriers as with existing Release '99 W-CDMA services. A system may be upgraded incrementally to enhance performance for users of the latest handsets without losing network capacity or interrupting service to subscribers who rely on older handset technology.
As an extension of GSM, HSDPA can be deployed readily in the United States, Europe and Japan. In fact, some service providers may introduce pilot projects within the next year. By 2007, HSDPA likely will be a leading technology worldwide. This means that operators will be able to offer global roaming capabilities based on infrastructure already in place today and serving a sizable handset base, including older W-CDMA units.
HSDPA's incremental upgrade and dramatic performance benefits will serve as the best stepping stone to 4G for many operators. Texas Instruments is working within the 3G Partnership Project (3GPP) to enhance the standard in ways that will provide continuing business opportunities for wireless operators.
Among the developments we see down the road is high-speed uplink packet access (HSUPA), which will augment HSDPA to create a more symmetrical high performance system. We also expect ongoing improvements to boost network efficiency, reduce latency and increase overall network throughput.
All of this can be achieved through incremental upgrades to time proven W-CDMA technology. The HSDPA standard has been in place for a couple of years. Base station equipment is now starting to reach the market and handsets will follow, with widespread deployment anticipated in 2006 and 2007.
For consumers, HSDPA will help 3G technology fulfill its promise with more sophisticated data applications and better performance. For operators, this technology enables a highly competitive network with only incremental enhancements to existing infrastructure. HSDPA promises to provide a better return on investment and stronger revenues per megabit delivered compared to other avenues to very high-speed service.
