Standards Watch : On the EDGE

Operators are now offering a groundswell of support for EDGE (Enhanced Data Rates for GSM Evolution). AT&T Wireless, SBC, BellSouth, Rogers, Cingular Wireless and other TDMA operators in the Americas are enhancing data capability over the core GSM network with EDGE.

EDGE offers a path to GSM that U.S. operators would otherwise not have. Unlike many foreign operators, who have paid prodigious amounts of money for licenses that set aside 3G spectrum, U.S. providers have no natural progression toward 3G. It is expected, therefore, that the evolution in the U.S. market will be from GSM to GPRS to EDGE, and then maybe to 3G. EDGE, ostensibly, is a transport mechanism that sits on top of GPRS. It promises to enable wireless carriers to triple the number of users and double the throughput possible with GPRS.

As a transport layer, EDGE delivers advanced mobile services, such as video and music clips, full multimedia messaging, high-speed color Internet access and email.

U.S. operators are now positioning for capacity in preparation for adopting packet data service strategies common to GSM, including GPRS, EDGE and WCDMA.

The first to commit to that strategy was AT&T Wireless (ATWS), which committed to EDGE more than a year ago. “Global volumes and the potential for data roaming on a global scale made the decision for GPRS/EDGE pretty simple for us, since these options can be deployed in the current spectrum,” says Leo Nikkari, director of 3G industry relations at AT&T Wireless. It was the first U.S. operator to put a national RFP for GSM-based data on the table in 2000—initially for an EDGE adjunct to its TDMA network. “We were very pleased to receive competitive bids for a complete GSM/GPRS overlay to our national TDMA network, which included a software upgrade to EDGE,” says Nikkari. Under the UWC-136 umbrella, ATWS has developed the only TDMA-based proposal for IMT-2000 that was approved by the ITU-T in 1999 (IMT-2000 SC).

The Need for Speed

There’s little doubt the popularity of EDGE will be fueled by demand for high-speed data services in advance of UMTS in markets such as North America, Latin America and Eastern Europe.

EDGE’s theoretical peak rate is 470 Kbps; in practice rates are expected to average 80 Kbps to 150 Kbps. “GPRS has theoretical peak speeds of 115 Kbps but will typically deliver average throughput rates of between 40 and 45 Kbps,” says Bill Clift, CTO of Cingular Wireless, which was drawn to EDGE because of its 3G data speeds and the minimal investment required to add EDGE to a GSM/GPRS system. He believes EDGE is a 3G technology that costs less than a UMTS overlay.

One of the major attractions of EDGE as compared to GPRS is that companies like Cingular can offer a data service equivalent to GPRS using one-third the amount of spectrum, allowing a GSM operator to move quickly to a threefold increase for GPRS service, as well as freeing up spectrum for additional voice capacity, and enabling early trials of high speed (3G) data services not possible with GPRS.

More than the speed, the key to EDGE is that data-intensive applications can be used in a mode that is more acceptable to the customer, according to Clift. He expects EDGE speeds will enable devices that are capable of true Internet browsing, interactive gaming applications, multimedia downloads and a full range of enterprise system applications.

Projected Growth

Many think EDGE will greatly enhance the types of services operators can market. As a percentage of cellular subscribers worldwide, the market share of EDGE users is forecast to rise from 0.12 percent in 2003 to 13.6 percent in 2007, according to U.K.-based analysis and research firm ARC. The firm forecasts growth of EDGE users to 331.4 million globally by 2007. In its study “The Future of EDGE” (www.arcgroup.com/edge), ARC looks at the deployment of EDGE as both a standalone network technology in markets such as North America and as a complement to UMTS networks in Western Europe. The study further reports that wireless data services provided by EDGE will account for 27 percent of monthly average revenue per user (ARPU).

In regions such as Western Europe, where UMTS licenses have been auctioned, the key driver for EDGE will be to complement UMTS technology. “That will provide 3G-like coverage outside the UMTS network footprint in an islands and seas approach,” says Rupert Reid, publications and consultant manager at ARC.

EDGE Devices

EDGE’s proliferation will depend on resolving the question of devices.

The founding members of 3G Americas (www.3gamericas.org) are working on those issues with its members, including ATWS (USA), Cingular Wireless (USA), Compaq, Ericsson, Lucent Technologies, Motorola, Nokia, Nortel Networks, Openwave Systems, Rogers Wireless (Canada), Siemens and Telecom Personal (Argentina).

“The focus now among manufacturers will be support of operators’ business plans, as they figure out services and how to charge for them,” says Alan Hadden, president of the Global Mobile Suppliers Association (www.gsacom.com). The organization is a lead sponsor of the EDGE Operators’ Forum. “From 2003, there will be a wide cross-section of terminal types that incorporate EDGE functionality in line with operator demand,” says Hadden. Most vendors have announced plans to ship infrastructure capable of operating in all GSM bands (850, 900, 1800, and 1900 MHz).

“We have already seen the availability of tri-band phones, working at 900/1800/1900, from a number of leading vendors, with plans announced to bring 850/1800/1900 MHz phones to market in the near future,” Hadden says. He expects the addition of the 900 MHz band, also widely used for GSM networks in Europe and Asia-Pacific, will follow.

It seems all the major manufacturers have committed to producing EDGE equipment. “About 95 percent of all equipment shipped for GSM is EDGE-capable,” says Hadden.

In TDMA markets being overlaid with GSM, EDGE-compatible hardware can be upgraded to EDGE via a software update. In existing GSM markets, there will be an EDGE-capable radio in each cell and sector. These radios will be purchased through the normal course of adding growth radios to systems.

“We have four equipment supplier partners, all of whom have committed to deliver EDGE hardware and software to us,” says Cingular’s Clift, noting that several device manufacturers have committed or offered to incorporate EDGE into their handsets, PDAs and PC cards. “We expect to see the first commercial EDGE device in the fourth quarter this year, with higher volumes and more variety available starting in the first quarter of 2003.”

Nikkari at ATWS also believes the major vendors are providing sufficient support for commercial EDGE deployment in late 2002/early 2003. “We expect all mid- and high-range terminals to support both EDGE and WCDMA by the end of 2004,” he says.

The equipment ATWS is installing for GSM/GPRS will enable the organization to upgrade software to EDGE when additional capacity is needed. “We are also making sure to have a further hardware and software upgrade to WCDMA when we need even more horsepower,” says Nikkari. Technically ATWS can deploy WCDMA in 1900 MHz markets where 10 MHz is available, but that will depend on market requirements for such services.

EDGE and WCDMA are complementary technologies, built on a common 3G core network. “There is a common fallacy that EDGE and even GPRS are interim solutions until 3G arrives,” says Nikkari. But “both GPRS and EDGE will remain in the current narrowband spectrum markets based on global 200 KHz radio engineered options, even when WCDMA is deployed in new bands.”