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Microcap & Penny Stocks : Globalstar Telecommunications Limited GSAT
GSAT 60.01+0.4%Jan 9 9:30 AM EST
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To: finite_time who wrote (15977)8/20/2000 9:40:08 AM
From: rf_hombre  Read Replies (1) of 29987
 
finite_time, re:System Capacity for Voice>I think you may be confusing "beams" and "frequencies" when you say "channels". Going back to your calculations:

1250000 Hz per channel / 9600 Hz = ~130 users / channel

This is not possible, there are a fewer number of usable Walsh codes than 130!

There are 13 theoretical frequencies to choose for each Gateway but adjacent Gateways cannot be allocated the same frequencies so early in the life of the GW a subset of the 13 are defined. Let's take 6 for argument's sake.

Furthermore in a coverage area of a GW, there are 16 beams in the Downlink and Uplink directions so in actual fact you end up with:

6 frequencies * 16 beams * 56 (approx. number of Walsh codes for traffic) = 5376 theoretical connections.

(If memory serves me right there are 64 Walsh codes with 8 logical channels for pilot,paging and synch.)

This is really a best case that assumes that each geographical spot beam area is filled to capacity. In reality, for now the number of outgoing PSTN connections will probably be the limiting factor.

Anyway, taking 40 seconds as average call holding time with 2% Grade of Service yields on an individual GW basis:

(5376 Erlangs of Traffic) / (1/40) = 215 000 Subscribers

That is, with all CDMA codes maxed out and all 16 beams filled, a gateway can support 215 k subs with 2 % Grade of Service.

Finally max CDMA capacity per GW is: 215 000 * 100 (MOU/month) * 12 = 258 M minutes/GW
Applying this result to 40 GW’s yields about 10.3 B minutes.

rf_hombre
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