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To: quidditch who wrote (29510)	5/8/1999 10:06:00 PM
From: Terr	Respond to of 152472

> PS, do you have the medved link?) Medved QuoteTracker can be found at quotetracker.com or the mirror site medved.net There is also an SI tech. support thread for it at Subject 22551 or a Yahoo club post.clubs.yahoo.com Enjoy.

To: quidditch who wrote (29510)	5/10/1999 9:39:00 PM
From: Clarksterh	Respond to of 152472

Steven - is the relative spectrum inefficiency of W-CDMA attributable to the hybridization of TD/CD, or for other reasons? Certainly TD'ing the signal will impact capacity to some degree due to the fact that you need to make sure that each time slice does not interfere with its neighbors coming in from other parts of the cell. But this is probably a pretty small effect. I think other factors like turbo codes, synch of basestations (synch is used in yet another way, but one which I do not completely understand), handoff, vocoder rate sliding, ... all play at least as big a role. It's the last sentence of the quoted text of the proposal whose import escapes me: <The reason why the maximum number of channels in TDD is only 50% of that in FDD is the UL/DL sharing of one 5 MHz carrier in TDD."> Does this not occur in CDMA2000?). In CDMAOne the uplink and downlink use very different parts of the spectrum. Thus 5 MHz in CDMAOne might carry 30 forward links, but in W-CDMA it might carry 15 forward links and 15 reverse links. This is not possible unless you use TD. The reason is that when you broadcast you will, on average, be putting out many milliwatts, but you are trying to receive signals thousands of times weaker. If they are both at the same frequency and same time the signal you are broadcasting will swamp the signal you are trying to receive. Note that this will get really hairy when trying to coordinate neighboring cells. You need to make sure that a mobile in a neighboring cell is not broadcasting when you are trying to listen. (I need to do some more research here.) Hope this helps. Clark