americasnetwork.com
Harmonization Holy Wars
The standards soldiers are fighting over how well they need to work together...
By Arielle Emmett
The wireless world wants to mate multimedia with the higher speeds of third-generation (3G) networks. Indeed, it would be easiest and most cost-effective to implement one 3G wireless standard. But operator economics militate against simplicity, and standards-makers are carving out their 3G turf with political flair.
Add three types of 2G digital networks (GSM, TDMA and CDMA), several 2.5G interim data transport standards and the risk of adding new infrastructure for yet-unknown user demand, and you have standards soldiers shifting between diplomacy and trade war.
Each to Its Own Standard
Will operators worldwide will deploy 3G wideband CDMA (W-CDMA), the proposed global standard, or something else?
"From the U.S. GSM operator?s perspective, the question is whether most operators worldwide will ultimately deploy 3G wideband CDMA [W-CDMA], or something else," notes Prodip Chaudhury, director of systems engineering at Siemens. "The GSM operators are going toward the higher bandwidth General Packet Radio Service [GPRS] as an interim solution at 115 kbps." TDMA operators, he says, are leapfrogging to EDGE (Enhanced Data rate for Global Evolution), which delivers 384 kbps at full mobility, and the IS-95 CDMA people are looking at 1XRTT, a 144 kbps standard for data that is the first step in a perceived evolution toward CDMA-2000.
"In the U.S.," says Chaudhury, "no GSM operator is thinking about W-CDMA because the EDGE standard gives you adequate bandwidth up to 384 kbps at full mobility. In Europe, W-CDMA will not see significant deployment until late 2002." In some cases, the interim standards, GPRS and EDGE, may work. "Because of the Internet, the situation is different from before ? and everybody in the past has been wrong in their projections," says Chaudhury.
You Say You Want a Resolution?
Harmonization groups are dealing with lots of unresolved 3G issues. For example:
? No one knows what future demand for wireless Internet services will be, although vendors believe wireless Internet will be a killer app.
? The subject of adequate 3G spectrum is up for grabs, especially in North America.
? Nearly everyone agrees that there never will be a single 3G global solution, but rather an interlacing of many solutions.
? Finally, "some of the vendors are claiming that GSM base stations deployed today would be made EDGE-compliant by only a software upgrade whereby they can download more advanced, higher speed protocols for EDGE," says Chaudhury. "However, it should be noted that since different modulation and coding schemes are involved in EDGE, new hardware must be accommodated in existing base stations. Therefore, the ?EDGE-ready? base stations are already equipped with this new hardware waiting for software download in the appropriate time frame."
If an operator publicizes its desire to go with EDGE, it might be disqualified from getting IMTS-2000 spectrum.
European vendors are hedging their bets on which higher-speed solution will be adopted. "If GSM operators decide to migrate to EDGE, they might ask themselves why they should go to W-CDMA, which buys them 2 Mbps, but only in stationary mode,"explains Chaudhury. "The true dilemma is that if GSM operators broadcast the fact that they would like to migrate to EDGE, since it is less costly than a full W-CDMA upgrade, they could be disqualified from getting licenses in the IMT-2000 spectrum."
Here are some statistics:
? Japan will launch 3G W-CDMA (also known as IMT-2000) in 2001;
? Fifteen countries in the European Union must begin IMT-000 deployments no later than January 2002;
? In the UK, 13 consortia have already invested US$80 million to buy IMT-2000 licenses; and
? Licensing is underway in Germany, the Netherlands, New Zealand and South Africa, according to the Global Mobile Suppliers Association (GSA).
Of the GSM operators ? over 400 in 42 countries ? most are planning packet-based GPRS deployments for Internet support and high-speed wireless, according to Alan Hadden, president of GSA. As networks evolve, "we expect between 80 and 100 licenses for wideband CDMA [IMT-2000] worldwide," he says.
At the beginning of the migration, "most GSM operators will go with GPRS, some will choose EDGE at 384 kbps for data, and some will stop at EDGE," says Hadden. "But others will wait for IMT-2000, because they?re in the bigger markets and need the network capacity."
Let's All Get Along, Shall We?
Engineers are at work on network harmonization efforts, which include developing software, coding and equipment upgrades in the core networks to prepare for high-bandwidth multimedia services and developing systems to harmonize two different 3G CDMA operating solutions (W-CDMA and CDMA-2000) that ultimately will ?talk? to each other.
In the TDMA camp, the migration to 3G is from IS-136 to GSM/EDGE, which means ANSI-41 is now tied to the GSM air interface.
The GSM Association, Universal Wireless Communications Consortium (UWCC), European Telecommunications Standards Institute (ETSI), CDMA Development Group, (CDG), International Telecommunication Union (ITU) and Third Generation Partnership Project (3GPP) all have roots in different continental and networking camps. The 3GPP is hammering out specs for the launch of 3G services in 2000 and 2001 in Japan and Europe, respectively. The primary standard, IMT-2000,contains specs for narrowband and wideband CDMA and TDMA. Because of support from the GSM community ? which vastly outnumbers the other subscriber camps ? W-CDMA is expected to be the 3G standard by which all other proposals are measured.
"What a lot of people miss is all the work going on in the network side to resolve 3G issues. There?s a tremendous amount of standardization required," says Brian Kiernan, senior vice president at InterDigital Corp., maker of chipsets for advanced 3G systems.
Standardization involves worldwide network modifications that mate different global air interfaces with core networks. Moreover, the global ITU standard for W-CDMA accounts for different modes of operation.
"For example," explains Kiernan, "W-CDMA has both a frequency division duplex [FDD] mode and a time division duplex mode. Beyond that, you have another version of CDMA ? multichannel CDMA, known as CDMA-2000, which is an FDD standard only." CDMA-2000 also promises full 3G capability, including IMT-2000 interoperability and 2 Mbps data rates.
In the TDMA world, "there is now DECT for short-range operations and F-TDMA, an evolution of IS-136, which is fundamentally the new GSM/EDGE air interface standard," continues Kiernan. EDGE is considered 2.5G ? a mobility standard that AT&T Wireless and other TDMA/GSM operators are planning to implement in North America. EDGE is based on GSM packet data ? actually, GPRS with a new modulation scheme.
And that?s not all. "You have two separate mobile networks, ANSI-41 [which supports CDMA and TDMA IS-136 networks] and GSM, and there?s an immense amount of work required to provide seamless roaming and 3G on both," notes Kiernan.
The Race of the Acronyms
The GSM alliance and ANSI-41 committee have agreed to make the two principal networks interoperate.
In the TDMA camp, the migration path to 3G is from IS-136 to GSM/EDGE, according to Kiernan. "What that means is that the ANSI-41 network will be tied to the GSM air interface, and that?s very different from before," he says. "If someone with a GSM phone is running from Europe to the U.S., he doesn?t have to tie into our ANSI network [using a North American IS-136 phone]; he can tie into the ANSI network through the EDGE air interface [using the GSM phone].
The power of GSM and its loyal followers have given its heir apparent, W-CDMA, an international edge.
"Through ANSI-41 EDGE," adds Kiernan, "you add roaming capability to anyone who is GSM-enabled, so in effect it?s a worldwide, ubiquitous TDMA network. Once you?ve got the GSM air interface/EDGE mated to the ANSI network, you?ve already accomplished about 90% of the W-CDMA network interface. That?s another possible migration path."
Here?s one more: CDMA supporters have outlined an entirely different path to 3G. It includes several different functional iterations of existing CDMA, including a 3G multicarrier iteration (3G MC 1X) that will provide up to 307 kbps data rates and double the voice capacity and standby time (see box, below) of IS-95.
Qualcomm Inc. is pushing heavily for its High Data Rate (HDR) standard, something roughly equivalent in functionality to the interim EDGE standard in the TDMA world ? a data-only network overlay using 1.25 MHz channels to deliver high-speed fixed and mobile Internet access at claimed speeds of up to 2.4 Mbps.
As Qualcomm and CDMA operators like Sprint PCS evolve to true 3G CDMA, the carriers will offer varying flavors of IMT-2000 wideband CDMA compatibility.
"W-CDMA systems must be proven in the field with capacity-loaded networks," says Anil Krapalani, senior vice president of planning and international administration at Qualcomm. "But CDMA 2000 multicarrier mode is based on IS-95 proven technology. In short, we use the same basic methodology to evolve to 3G, and the air interface has improved to support higher data rates as required by IMT-2000."
Krapalani makes Qualcomm?s classic argument: that an investment in CDMA-2000 networking means cost-effective, backward compatibility with existing IS-95 networks. "The multicarrier mode [1XRTT] based on 1.25 MHz is an ace in the hole, because it works on top of existing IS-95 MHz ," he says.
"HDR supports higher data rates and also supports 1.25 MHz channels [with mobility speeds for data up to 2.4 Mbps]," continues Krapalani. "Because it?s only data and packets, we can bring the two together in one device, in one chipset, and that becomes a winning approach."
IP over GSM?
The political tone is evident. Existing operator equipment and service investments require unique branding and marketing work against a unified international 3G solution. Still, vendors and operators need to follow a cost-sensitive path.
Vendors expect that consumers will exhibit insatiable appetites for Web downloads and messaging; streaming media, color graphics and wider handheld screens; Java-enabled location-based applets; Internet browsing, and access to corporate Intranets through secure firewalls.
'There is no new spectrum for wireless multimedia. The U.S. doesnåt follow the rest of the world.'
- Alan Hadden, GSM Association
Virtually all wireless Internet browsers will offer compatibility with Wireless Applications Protocol (WAP), says Chuck Parish, executive vice president of Phone.com. "WAP is the application platform, but with 3G operating, you?ll have better capability to offer multimedia, rich graphics, color, streaming audio and video. You?ll get a mixing of text and voice in the interface, and the Web will be designed [to] have different profiles for different classes of devices."
Wireless Internet apps are expected to drive mobility over the next several years. "For the Internet we need more speed and IP packet switching.," says Alan Hadden, president of the GSM Association. "We?re seeing the first increases in speed through GSM?s HSCSD [high-speed circuit-switched data], which has boosted 9.6 kbps GSM data to 14.4 kbps and will increase soon to 57.6 kbps. More than 40 GSM operators worldwide have already launched or used these services, and the networks are preparing for GPRS with more speed potential, up to 115 kbps.
Arielle Emmett is a freelance telecommunications/IT writer and editor, and is a regular contributor to Americaås Network and Wireless Americas. Send comments via mslepicka@americasnetwork.com. |
