Which network--CDMA or GPRS? No easy answers

Microsoft's recent announcement that it has added CDMA support to the phone edition of PocketPC is an important story to any corporate customer traveling the WAN upgrade road.

Microsoft's announcement makes it possible for manufacturers of PocketPC Phone Edition-based PDA/phones (like Samsung) to supply devices to operators of CDMA networks (like Sprint and Verizon) in addition to the operators of GSM/GPRS networks (like T-Mobile and Cingular) with which PocketPC Phone Edition was already compatible. GSM handles voice, while GPRS (General Packet Radio Service)handles data.

The cross network availability also broadens the target for developers of wireless applications that depend on a PocketPC based client. Prior to this announcement, if you or your company depended on PocketPCs and you wanted to mobilize an application using PocketPC Phone Edition, you only had one choice for a wide area data network: GPRS.

As a side note, Microsoft was late to the cross-network party. The PalmOS-powered Treo PDA/phones from Handspring are already available for both networks. The other competition to Microsoft on the mobile operating system front --- Symbian (of which Nokia and Samsung are licensees) --- also supports both networks.

Now that all three mobile operating systems support both voice/data networks, the next question facing corporate developers/users and consumers who didn't have to think about the network before is: Which network?

To answer this and other questions, I contacted John Strand, of Copenhagen-based Strand Consult, who recently authored a report that said GPRS has so far been a bigger flop than WAP.

As it turns out, there's nothing wrong with GPRS -- at least nothing that we don't already know. Strand was referring to GPRS' as yet unfulfilled potential from the operator's side of the equation. But, for users, there are differences between the networks. For example, despite the advertised data rates of both networks, Strand notes, "most GPRS users are lucky if they get between 32 and 36 KBps. CDMA users are getting at least twice that--somewhere between 70 and 80 KBps." This corroborates some positive feedback I've heard about the performance of Sprint's PCS network when compared to the GPRS-based alternatives.

Simply because CDMA is going twice as fast as GPRS, and exciting services like Sprint's video phone look, well, exciting, doesn't mean that we should all run to CDMA, says Strand. Since pricing for similar bundles of voice and data from both camps are about the same, it would seem as though you get more bang for your buck from CDMA.

But Strand advises users to consider other criteria before making a decision.

"The most obvious one," says Strand, "is coverage. Going with CDMA won't be very helpful if most of your people are running around in area that doesn't have very good CDMA coverage." The same goes for GPRS.

Assuming that you or "your people" run around in areas covered equally by both networks, your next consideration should be the applications you are running. Strand divides applications into three tiers: light, medium and heavy.

"Light applications" says Strand, "are ones like e-mail that don't require a lot of bandwidth. Medium apps are the type where you need real-time access to facts and figures and are submitting database queries and things of that nature. Heavy apps include streaming video clips, working with large images, or downloading big documents like PowerPoint or Word documents."

Either network will suffice for applications whose maximum bandwidth requirement falls somewhere between medium and heavy, says Strand. But once you enter the world of heavy, CDMA is your only choice. E-mail is pretty light, until you enter the world of Microsoft Office and PocketPC. Given PocketPC's support of documents created in Word and Excel (and similar functionality that can be had on PalmOS and Symbian), we certainly aren't discouraged from sending or receiving large documents. If your users like to take full advantage of a mobile device's capability to work with MS-Office documents, then CDMA certainly looks good on paper.

Value added by operators
Another area that Strand suggests looking into is the menu of value-added services provided by the mobile operator. Strand is particularly critical of American operators. "Whereas other operators around the world will show you a road map for the additional services and APIs that they're going to make available over time, American operators are little more than dumb ISPs," he says. Leaving room for one or two innovative offerings like Sprint's Business Connection, Strand says, "for the most part, American operators offer two things--voice and data." It's no wonder that users and companies have no idea which way to go when choosing networks.

Strand points to South Korea as a country that has fully embraced a single infrastructure (CDMA) and where the operators are proactive about value-added services because they represent the biggest opportunity for additional revenue. The Korean operators also are keen on making those services available to third-party developers through APIs.

Provided the right APIs are available, a developer could write an application that allows a phone user to assign a voice or data transmission to a client's account, and integrate the charges into a billing system (regardless of where it is hosted). Sounds like a job for Web services.

That corresponds to the answers Microsoft gave me when I asked if PocketPC developers needed any "IF-THEN-ELSE" statements in their source code to deal with network dependencies. If that was the case, then understanding those network dependencies might affect the GPRS vs. CDMA decision. According to Microsoft's Jason Gordon, that depends on the mobile operators and what APIs they make available to developers. Right now, says Gordon, there's no difference. Like Symbian and Palm, PocketPC's equal access to both networks will help to level the playing field for developers. Eventually, if the operators do come up with services that they want to make available to developers, their best bet will be to work with the operating system providers to make sure that the APIs to those services are exposed in Software Development Kits (SDKs).

Can mobile operators change their spots? Despite the glut of bandwidth, the telecommunications service providers (land and air) continue to overcharge for voice and data. Sooner or later, if public 802.11 networks don't come from nowhere and kill 3G altogether, that market dynamic is going to come back to haunt them. When it does, the operators that survive may very well be the ones that can transform themselves from pipe providers to platform providers. Who that will be is anyone's guess.

Unfortunately, this is one important data point that's tough to fill in if you are trying to make an informed decision today.

What has your experience been with CDMA and GPRS? Share your thoughts and opinions using TalkBack below, or write to me at david.berlind@cnet.com.