If you would like to perpetuate the myth that so far as 3GPP is concerned there is no valid reason other than a Q IP workaround for utilizing 5 MHz carrier, asynchronous as well as synchronous mode of operation, AMR, authentication with SIM, etc, etc., feel free to do so.
Given what Dr. IJ said (below) at the recent analyst presentation in response to the question "Why is WCDMA lower in capacity?", combined with the 2-3 year delay of WCDMA (vs CDMA2000) it's hard for me to see how WCDMA is anything other than a (failed) attempt to avoid Q IP.
IJ: With respect to the differences in performance; when the standards groups were getting together and trying to design WCDMA, there were several factors driving them. One of those was to try to make it different from what we were already doing with CDMA. So for example, going asynchronous rather than synchronous. That means it takes a little bit longer to do a time search, to do a handoff, and that actually has a little bit of a quality and capacity implication to it. The kind of vocoding that was introduced was a little bit different, not the full variable rate that we make use of, and so that has a little bit of an implication. The number of codes that they have available, Walsh [?] code capability that they have available limits the number of calls that can be up.
When you go to a wider bandwidth, which by the was we also thought for quite a time you needed to efficiently to handle high speed data, until we came through with the breakthroughs we put into 1x, and EV, DO and therefore gave high speed data efficiently in the smaller bandwidth. Until then, we thought we would have to go to the wider bandwidth to handle data, but it wasn't really optimal for voice in the sense that voice is a narrow band process.
When you go to wider bandwidths, and I'll get slightly technical here, what happens is that the multipaths [?], the fact that radio waves bounce off many different objects, you end up, because of the higher bandwidth, that each one of these multipaths has kind of a shorter time period to it, one over the bandwidth [?] in a sense, so you end up with 4x as many of these reflected signals that you then have to build little receivers to receive. But each one has less energy in it, so it's harder to receive. Well, the kind of equipment that's being built, if you put more of these receivers there's more expense. Currently they're getting by with a smaller number and that has a performance impact.
Power control is done a little bit differently again, probably either to try to avoid some patents, or to include somebody else's patents. Again not quite done, although not well specified, but not necessarily done quite as well.
So there's a whole variety of things here and there that as we carefully try to analyze, and also absorb the data that has been published, and that we do ourselves, because of course we're working very actively on WCDMA, that's where we're coming up with this shortfall in performance in WCDMA vs 1x.
1x has had the advantage of starting with 95A & B and we've learned a lot. We found that we were very conservative with some of our estimates. We found that we were able to, for example on the link from the phone back to the base station, it was a little more stable than we originally assumed, we were able to put a little bit more pilot [?] energy which improves the performance.
So the whole set of these things that we were able to build in that I think will be able to take another cycle on WCDMA. So over time it will improve, but if you look at what is currently being launched -- late, based on everything we now know, the waterfall chart shows that the performance is just not up to that of the equivalent 1x carriers. Over time it will improve, over time 1x will improve. |
