Re - Is a chip rate of 3.8xxxMcps even marginally more compatible with cdma2000 than 4.0xxxMcps?
Marginally - maybe. But not much more (it might make frequency planning for CDMAOne upgrades a little easier, but I'd have to think about it to make sure). As Ericsson is itself aware there is a large advantage to having the various chip rates be multiples of one another - Ericsson documentation talks about using multiples of the original 4.0xx. 3.8 is not a multiple of the original CDMAOne chip rate so they will probably need to install entirely new timing systems in all of their basestations. It also means that CDMAOne operators cannot easily combine three CDMAOne channels out of, say six, into one 3g channel. This also loses some backward compatibility and puts the CDMAOne operators on more of the same footing as the GSM operators.
2. While the rate is important relative to existing infrastructure for Q, does the change in rate have any definable impact on transmission speeds, capacity, base station density, etc.? (Meaning what are the advantages or disadvantages for performance depending on the rate.)
Everything else being equal a higher chip rate provides higher data rates. But of course everything else is not equal. As was made clear about Ericsson's earlier chip rate in some of the technical articles, the 5MHz requirement meant that such severe filters were needed that performance was impacted enough to negate the higher chip rate. As for whether 3.8 really provides meaningfully better performance - I guarantee not, but exactly which system will provide the marginally better performance is not knowable without very detailed models to which no one on this board has access (other than possibly Sanjay).
3. Why choose 3.8xxx, other than to screw existing cdmaOne users? Is there something WRONG with 3.6xx?
There are only two good engineering reasons to pick a chip rate. Performance and backwards compatibility. As was just discussed 3.8 provides no noticibly(sp?) better performance than 3.6x, and backwards compatibility with GSM is impossible anyway. Thus Ericsson did not use either of these criteria in picking the rate, so they must have picked it as a public relations ploy and to screw Qualcomm.
You really, really have to admire Ericsson's ability to manipulate the press and the public. It sounds so reasonable to a layman and yet it is complete horse pucky.
Clark
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