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To: Asterisk who wrote (12403)	7/15/1998 5:04:00 PM
From: Steve Hamilton	Read Replies (2) \| Respond to of 152472

Mistake is that you are not accounting for power consumption by the chipset itself. The actual ASICS use much less power than GSM/TDMA systems, and the lithium ion battery is used much more efficiently. In real world samples Qualcomm's phones outlast Nokias by a 2 to 1 margin at the worst. S

To: Asterisk who wrote (12403)	7/15/1998 5:25:00 PM
From: Bux	Read Replies (2) \| Respond to of 152472

From one Michael to another, Yes, I think your assessment of power consumption is way off base. I am no tele-techno wizard but I do know the basics and you have neglected to consider the biggest power saving feature of CDMA in your analysis. A CDMA network utilizes active power control to insure that all signals arrive at the base station at the same strength. Since signal strength diminishes with the square of the distance, phones that are near a base station transmit at a small fraction of the power required for "old fashioned" phones.

To: Asterisk who wrote (12403)	7/15/1998 5:57:00 PM
From: Clarksterh	Read Replies (1) \| Respond to of 152472

Michael - Although you brought up some points I hadn't considered, you are making at least one big mistake, and, I suspect, some smaller ones: 1) Lets take a specific example. If we hold both powers at max AMPS transmit (28dbm) then the TDMA pulsed transmit would take less power. If your PA is only on for 1 out of 10 time slots then you would take max 1/8th the power right? No. The reason is that you are making the assumption that they both require the same raw power out, when they do not. They require the same processed Eb/N. Thus, for instance, GSM packs all of their info into one time slot with the result that their bit rate is (assuming a duty cycle of 1/8) 8 times higher. Therefore, for that time, they need 8 times the power. Broadly speaking, you don't save power by going digital (no matter what format) except insofar as you can decrease the transmission of useless data. CDMAOne happens to do this better than GSM. 2) If you have a slotted system then you can afford 2 things, 1) more noise, and 2)less isolation. In a CDMA system you have to have some type of filtering to seperate the transmission of Recieve and Transmit signals. This filtering costs tons in the way of transmit power and power in general. In GSM you have no need for this filtering, your time slot is yours, either recieve or transmit whatever you want. Well, I agree this is a good point, but I suspect it isn't too significant. The send and receive are separated by 45 MHz, which is a lot for for a channel only 1.25 MHz wide. The filter should easily be down well in excess of 100dB. However, I'll admit I'm not a filter designer. 3)The corollary to this is that when you have your own slot you need not worry about the noise you are transmitting inside your band. Noone else is affected so who cares? With CDMA (a noise limited system) ANY noise that you add to the system that is not directly associated to your communication will lower the capacity of the entire system. This never occurred to me, but again I suspect the effect isn't that large because in GSM the transmit noise floor is a much bigger factor in the received S/N (nobody else is transmitting), whereas in CDMA the noise floor created by the intentional transmissions of other users is 30dB higher than the noise transmitted by the broadcaster (assuming a transmit S/N or 40 and 10 handsets in the cell). Thus, even with 10 users in a band of a cell, the noise floor transmissions are only 1/1000 of the 'noise' caused by the other users intentional signals. Clark

To: Asterisk who wrote (12403)	7/15/1998 7:46:00 PM
From: Walter Liu	Read Replies (2) \| Respond to of 152472

This is not true. When you have a time slot, you transmit the same amount of power if you are talking or not in GSM. There is a feature called DTX, Discountinous Transmission. However, your voice quality suffer for the benefit of less interference. In CMDA, once you have a Traffic Walsh Code (like timeslot) in CDMA, the power transmit and receive is variable according to speech activity, thus requires less power and less interference. Once you have a timeslot in GSM, it is not totally yours, you share it with another user in frequency re-use concept. This is called co-channel interference, and if your filter is bad at the cell site, you got adjacent channel interference as well. GSM is less interference tolerate, less time dispersion tolerate. CDMA can actually combine multipath delay in time to turn them into gains rather than loss. A feature that GSM can never do due to 200khz narrowband signal. Both GSM and CDMA need filter to separate TX and RX, with 45Mhz separate, you don't need a expensive filter for either one. 1) due to the nature of GSM (TDMA) it will actually use less power when transmitting and recieving. Lets take a specific example. If we hold both powers at max AMPS transmit (28dbm) then the TDMA pulsed transmit would take less power. If your PA is only on for 1 out of 10 time slots then you would take max 1/8th the power right? in that example I assume that there is some penalty paid for the power up and down cycles. The lowest rate that the CDMA system transmits on is 1/8 rate. At that point you still spend 1/6th the power. Besides you will not be at 1/8th rate when you are speaking, only when listening and no information is passed. 2) Due to the nature of GSM (TDMA) the PA that they use is less power hungry and much cheaper. If you have a slotted system then you can afford 2 things, 1) more noise, and 2)less isolation. In a CDMA system you have to have some type of filtering to seperate the transmission of Recieve and Transmit signals. This filtering costs tons in the way of transmit power and power in general. In GSM you have no need for this filtering, your time slot is yours, either recieve or transmit whatever you want. The corollary to this is that when you have your own slot you need not worry about the noise you are transmitting inside your band. Noone else is affected so who cares? With CDMA (a noise limited system) ANY noise that you add to the system that is not directly associated to your communication will lower the capacity of the entire system. This causes the PA to be more complex and bigger, more lossy, more power hungry, etc...