Hi, Lance -
I'm not sure of the particular conditions in Korea, but in the current US environment, IS-95 provides an operator 12.5 MHz of spectrum, which will give 57 channels, assuming a three-sector cell site.
The beauty of CDMA is that the 58th caller can still be accomodated, (or handed off from one site to another), by using the so-called "soft degradation" feature of CDMA; ie., an increased bit-error rate will allow the extra users.
IS-95B provides the following features and improvements:
1 - efficient handoffs (CDMA-AMPS,CDMA-GSM,CDMA-CDMA)
2 - longer battery standby times (~two hundred hours)
3 - medium-rate data services (65-144 Kbps)
4 - improved capacity, (roughly 20%) coverage and efficiency
However, data transmission in IS-95B has a cost:
'The IS-95-B specifications have been written so that manufacturers of subscriber units and infrastructure equipment can potentially support data rates of up to 115 kbps. This leap in data speeds is attained by aggregating up to eight CDMA traffic channels for data transmission (8 x 14.4 kbps = 115.2 kbps). While data rates of 115 kbps will be possible with the IS-95-B standard, Qualcomm anticipates that operator requirements will initially warrant support of data rates between 28.8 kbps and 57.6 kbps on the forward link, and 14.4 kbps on the reverse link.
americasnetwork.com
So, it appears that it's the usual good news/bad news game.
Yes, you're going to have 20% increased capacity with IS-95B, but aggregation of channels for data transmission will eat into system capacity.
That's only my opinion, based on what I've been able to learn. I welcome correction by many others who know more.
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On the larger question of the promises of 3G there's no doubt that the proposed figures are deceptive. All of the high-end figures are a best-case scenario, that degrades as more users come online, and the network attempts to accomodate both data and voice.
What's going on here? Given population and usage growth in major urban centers worldwide, how long will it be until we're right back where we started, with full pipes (spectrum). Picture this: 10 years from now, when there's 4G in NYC, and everyone's trying to phone home because there's a snowstorm, will you be able to download a multimedia clip, at rush hour?
Not likely. You'll be lucky if you can phone home, just like now.
I tend to agree with Ray that the marketing efforts have obscured the reality. The only caveat I might add is that in off-peak hours, the systems will be able to supply some pretty good speed/data transmission.
The only answer that I can see, aside from VOIP, new technology, cellular architecture improvements, and other tweaks, would be more spectrum.
JMO ;-)
Jim |
