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To: Ruffian who wrote (66594)	2/12/2000 9:53:00 PM
From: Cooters	Respond to of 152472

Ruff, My RF aptitude is conceptual, not practical. I hope engineer can respond to the hunterk1111 YHOO post. Clark is out of town. Coots

To: Ruffian who wrote (66594)	2/13/2000 3:41:00 PM
From: engineer	Read Replies (2) \| Respond to of 152472

I think he must be strictly an RF engineer. I can't understand the explanation of CDMA. there are no 30 kHz channels. there are 64 overlapping 1.2288 Mhz wide channels, of which about 40-48 of these are used at any one time. he's right in that as you add users the noise floor goes up, but most carriers dial in the Eb/No level and NOT the dropped call level. I am surprised you choose to characterize it that way. What happens is that the conceptual cell radius that you read about is a book is not constant and many factors influence the coverage a certain cell site has. We have one here by my house. It is VERY one sided in how the cell coverage is laid out. On one side it has about a 4 mile coverage radius and on the other it has like a 1.5M radius. this is due to the geography and the CELL vendor as much as anything. the goegraphy dictates the line of sight that the RF can travel and the carrier dictates the basic noise floor that the cell can see. both of these cause teh poor coverage to ocur. Even more, the cell radius fluctuates in and out wiht other second order effects such as weather, solar activity, and such. I have seen the MOT cell in my area under Airtouch change as much as 3 dB in my local area. At the same time, the analog stuff would probably change by more than 6 dB for hte same phone. Also another event that affects dropped calls is the cell handoff paramters. This is highly vendor dependent. This is also highly PHONE dependent. If you have a bunch of phones on the network which are poorly designed in the RF front end, they will drop the call themselves. This happened in 1995 in Korea due to the total garbage that a couple of RF vendors were delivering to the Korean CDMA phone mfgs. these phones spewed out alot of inband noise as well as gave tough IP3 readings which caused the phone to register that it was transmitting higher energy than it really was. the result is that the phone keeps on trying to send and when asked to up it's power, the actual power is non-linear such that not too much of it gets to the BTS. the BTS then dropps the call because it cannot get enough signal to maintain the required call quality. I had a poorly designed MOTO StarTac in my Mercedes which acutally had burned out the PA in the car kit after only 3 weeks. It dropped calls alot. I had thought it was the network and went thru debugging this part. I found out after running an RF power meter test on it, that the phone itself was garbage. Mercedes was highly interested in the results, but it was not the network. In essence, I don't think you can "dial in" a dropped call parameter.