By Matt Desch

Processor power is not a problem. Voice coding is well served. New markets beckon for fixed access applications. We no longer need to tell ourselves that CDMA works, says Matt Desch, Nortel’s President, Wireless Networks. It’s time to discuss the advantages of CDMA — and to look to its future.

CDMAS: In your presentation at the CDMA World Congress, when you talked about the speed with which CDMA has been taken up compared with the time it took GSM to get established, you mentioned processing power as a reason CDMA may not have been viable 10 years ago.

Matt Desch: CDMA is a fairly complicated technology; the algorithms that are required in processing a CDMA call are quite complicated. One of the fundamentals of CDMA is that every mobile has to be kept at the same relative power level coming in to a base station, so you have to be able to be very fast and very precise in terms of making power adjustments in each mobile. That requires a lot of computing power both in the base station as well as in the mobiles. The power control technology has to be very precise. It has to be controlled very quickly in real time and so it is fairly processor intensive technology - much more so say than IS-54, IS-136 TDMA or even GSM in terms of the raw processing speed expected in a chip in a handset mobile. And 100 MIPs worth of power in a mobile might not have been cost-effective 10 years ago.
Even five or six years ago we were talking about how CDMA would require 50 MIPs. Everybody looked around for how many chips you could get that would do 50 MIPs and how much that would cost and said: "Boy this is going to be a lot more expensive than we like — it’s not going to be $100 a terminal". Now, that kind of technology isn’t that hard to attain and the prices of chips have come down dramatically so you’re not processor-gated in any way in terms of CDMA.

CDMAS: Are you surprised that technology met your needs so fast?

Matt Desch: No it’s called Moore’s law. Basically it says that every 18 months or so, the computer chip can operate at twice the capacity in half the space of previous generations. What that means is you that can almost forecast from now until the year 2000 what kind of computing power you’ll be able to put into a chip in a cellular phone or a PCS phone, how many instructions per second and how fast those istructions will be able to operate. It’s pretty mind-boggling: what today we can do on our fastest computer on a desk we can probably do on a cellular phone in two or three years. And if we can do that, then think of the kind of applications that you can have. We thought that you couldn’t go any faster than 100 MHz , then 250 and then we get to 400 and now... I thought we’d be gated by storage and by bus technology but we’re seeing very fast buses, we’re seeing terabyte storage. I think in five years we’ll be amazed at how far we’ve come.

CDMAS: Fixed access is seen as an application that while second to network deployment may actually catch up in the next ten years to twenty years especially in developing countries.

Matt Desch: It won’t take ten to twenty years. I think it’ll probably take three to five at most for it to really catch up. There are a couple of things keeping it back in developed countries. One is cheap spectrum. If you’ve got to pay an awful lot of money for the spectrum it’s going to make the business case a little more difficult to achieve. And the other thing is the ability to really drive the costs down to a very, very low level, say, $400-$500 per subscriber, which is really linked to technology and volume and so forth.
I think we’re going to see fixed access start to really explode in the next couple of years in developed countries just as it’s now doing in developing countries because competition is going require other ways for operators to get to their customers and wireless is really the most flexible, most efficient way of delivering primarily voice and low to medium speed data applications but also in the future high speed data.

CDMAS: You remarked at the CDMA Congress that there was a feeling that everyone was relieved that CDMA had established itself and that was all very well but next year you would have to take on more issues in terms of differentiation.

Matt Desch: In the first world congress I felt that everyone was saying since that there really weren’t many live applications: "Don’t worry this is going to work it’s a great technology."
What kind of struck me about the second congress was we weren’t saying a whole lot different. We basically were just saying: "Yes it does work... it does what we said it would do a year ago." That’s all well and good but I think the forums for other technologies out there are well beyond the stage of just saying: "The technology works". They’re well into: "How can we make new and exciting applications that will bring consumers to our service versus those of our competitors?" I kind of feel that the CDMA industry in the last two or three years has been constantly trying to prove itself when in fact it really didn’t need to work so hard at it. It’s a great technology, it’s proven itself to have the capacity, the call quality, the expandability and the future capability. It doesnt need to be pushed so hard and I think the credibility involved would be a lot higher if we could move on from trying to win some non-existent frequency or standards battle against other digital technologies and towards trying to push harder towards the next generation of CDMA itself.

CDMAS: Is that what you think the talking point would be or should be at the next world congress - and also differentiation?

Matt Desch: Absolutely. Differentiation in terms of services — in terms of what we can do. I think we have to talk a lot more about data and data applications. I think we have to talk more about how operators using CDMA can differentiate themselves from those using GSM or TDMA. I think we have to consider applications of this technology where it’s being used in new and unique ways. I think we have to stress innovation, which which has always been a hallmark of CDMA. We have to start demonstrating, talking about what are truly the advantages of CDMA and what CDMA can do.
CDMAS: One of the early promises of the technology was coverage in terms of base stations. Is this still an issue?

Matt Desch: Well, it varies by manufacturer so it’s hard to make a completely general statement but CDMA is able to achieve greater coverage than other technologies right now. CDMA is capable of using fewer base stations than you would use in another technology at the same frequency. But there are differences too between manufacturers of CDMA systems. For example, Nortel has something called a receiver noise figure - it’s very important in terms of deciding what your link budget is which lets you know how many cell sites you require for the same amount of coverage. Our receiver noise figure is under four decibels for 1900 Mhz and under 5 db for 800 Mhz which is better than our competition. That allows us to use fewer base stations when we engineer systems. So it’s not only variable by technology but by manufacturers.

CDMAS: Are you happy with what’s available in the area of voice coding?

Matt Desch: There are three voice coders in CDMA right now: the standard 8 kbit per second voice coder, the 13 kbit per second voice coder and the enhanced variable rate 8 kbit/s vocoder. No-one ever really used the original standard 8kbit/s vocoder . Some of the early networks did but everyone seems to be pretty much in agreement that that vocoder isn’t good enough for the kind of capability that CDMA is able to offer. All the networks in the 30 cities that we have up and running in the US — and the others around the world — are primarily the 13 kbit/s vocoder which everyone agrees is the best-sounding vocoder bar none. The new 8kbit enhanced variable rate - EVRC - vocoder is quite good: it’s certainly better than the original one and it’s almost as good as the 13 kbit vocoder. It has the advantage of course of providing additional capacity to systems.
Between them, I think I’m quite happy with the state of the art in CDMA vocoders. They certainly offer what has proven to be outstanding voice quality. In the networks that we have running right now there are all kinds of anecdotal stories we hear from our customers about how their customers tell them that people that they talk to don’t know if they’re on a wireline phone or not. That’s certainly pleasing because that’s the benchmark for which we’re all striving.
I don’t see any new vocoders coming besides the three that we have right now. What the priority should be is data standards, applications, features and the evolution to new standards like wideband CDMA.

CDMAS: Are you all ready for the next generation — whatever that might be?

Matt Desch: You’d think that’s where all the action is based on the press releases. In fact multimedia PCS, as I like to call third generation, is still four or five years away from true implementation. The real fight that’s on right now in the industry is over who’s going to own the IPR, who’s going to define the standards...
It looks like there are at least two approaches to it and I’m hearing a third — or maybe more. So it’s looking unlikely yet that there’s going to be a convergence in terms of one standard; not too surprising. In our case we’ll build to whatever standard or standards our customers choose.
I think probably the most important part right now in terms of this technology is that operators start weighing in with what they think that they want from multimedia PCS; we havent heard too much except from a couple of Japanese customers. Most everyone else is just experimenting right now and haven’t weighed in on what they think the system needs to do what they want it to do, what standards, where they’d like it to evolve from and to. We’ve announced that at least initially we’re going to work to make our existing CDMA systems compatible with the future wideband CDMA so we can take our customers into the future. If there are other standards emerging — and you know there are proposals set forth by particularly vendors in the GSM camp -— then we will consider making those technologies as well. And it’s not a matter of one technology over another, it’s a matter of being able to serve our customers.