Electronic Design

EDGE On The Cutting Edge

Imagine you're coming back from an exciting sailing trip. You've taken some video and want to share it with your friends. So, you prepare video MMSs and send them out. Thanks to the Enhanced Data Rate for GSM Evolution (EDGE) coverage of the remote area you're located in, the transfer is fast and smooth.

Most consumers don't really care about the underlying technology that enables them to retrieve and share information. Yet they expect a reliable network, good coverage, attractive services, long battery life, and low cost. That's just what EDGE offers.

EDGE triples data speeds over standard GPRS. The capacity of a single GSM slot increases from the current 9.6 kbits/s or 14.4 kbits/s to 48 kbits/s per time slot. By aggregating up to eight 48-kbit/s time slots, the advertised maximum rate of 384 kbits/s can be achieved. Today's networks and handsets support EDGE class 10, which leads to approximate speeds of 200 kbits/s in downlink and 100 kbits/s in uplink.

Evolution is the key word in EDGE. It uses the same time-division multiple-access (TDMA) frame structure, logic channel, and carrier bandwidth as today's GSM networks. As there are only minor differences between GPRS and EDGE, EDGE's impact on the existing GSM/GPRS network is limited to the basestation system. The transceiver and software must be upgraded if they aren't already EDGE-capable by default. The core network doesn't require any adaptations. Due to this simple upgrade, an EDGE-capable network can be deployed with limited investments and within a short timeframe.

The radio, firmware, and telecom stack on the terminal side need to be upgraded to support the eight phase-shift-keying (8PSK) coding scheme and the new features required by EDGE. Once the EDGE stack's integration is complete and the radio is validated, the added cost of an EDGE phone compared to a GPRS phone is small-and it will converge to zero once the technology is widely deployed. The introduction of EDGE doesn't affect the cell phone's battery performance, weight, or size.

With EDGE, operators can offer new high-speed data services, such as wireless multimedia, Web browsing, or e-mail to their subscribers in the business and consumer domains. The cost of these services can be reduced, because the tripled spectral efficiency lets companies serve more subscribers at the same time.

In North America, EDGE offers attractive characteristics for operators to compete with CDMA2000. While in Europe and Asia, EDGE will be deployed alongside UMTS (Universal Mobile Telecommunications System). Most operators who have licensed UMTS spectrum (also known as WCDMA) also own 2G GSM/GPRS spectrum. The available spectrum in 2G is typically larger than that of WDCMA. The question arises on how to deploy the new capacity and what to do with the existing subscribers and services. There's a trend toward upgrading the GSM/GPRS networks to EDGE and using UMTS to expand business as well as introduce new broadband services in highly populated areas.

The compatibility with existing networks and the possibility to offer a 3G-like user experience are the key drivers behind the strong deployment of EDGE. It isn't a matter of 3G or EDGE, it's a matter of 3G and EDGE.

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