That is because that 48 tap filter was "future" and "optional", QCOM didn't use any FIR filtering, just blasted the sky full of garbage..
Uh, the filter is necessary if your chiprate causes excessive out-of-band radiation. The FCC does not allow excessive out-of-band radiation. It would be fair to say they would have had one if they needed it.
I consider 4.096mcps to be a dead debate. But, since I have time to waste on you, lets get started.
Each customer increases the noise floor for others in the same channel. For voice, you end up dancing with TDD just to keep customers from laughing at your standby time. Smaller channels allows you to have more of them. Fewer customers per channel increases QOS overall.
Since the overall speed of your network backbone will prevent you from ever seeing the full 2mb/sec in laboratory conditions, I seriously doubt anyone in Finland would notice a lower chiprate and its smaller channel spacing requirement.
Here is one example of your garbage blaster with Qualcomm chips inside:
gullfoss2.fcc.gov
Help me out here. I am not seeing radiation outside of its operating channel.
Note also that if QCDMA for 3G would have been deployed in Finland it would have disturbed the neighbouring bands so much that one extra band would have been wasted.
A 200kHz guardband next to a 1.25mHz channel or an 800kHz guardband next to a 5mHz channel?
Since out-of-band emissions from a CDMA phone would appear to be gaussian noise to adjacent channel users (or look like increased background noise to adjacent licenses using analog modulation techniques in TV or radio broadcasting), Finland would do well to bring its regulatory practices into the 21st century.
Btw, even your old 56k modem has at least 128 tap filters, only academic idiots with no real experience do 129 tap filters (with MatLab, without any tool to properly optimize them)
I don't expect 100 hours of talk time out of my laptop.
But, you are comparing a filter designed to operate in a POTS environment where the frequency response can almost extend to 15khz to a 4mcps chiprate? I don't think you want DSP's cranking out those kinds of MIPS running for 100 hours on a tiny LI Ion battery that is already getting sucked dry by the color LCD display.
Unless, Nokia wants to be in a position of issuing oven mitts in colors that accent their pretty hi-temp plastics. |
