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Tetherless Wireless
TolkiEinstein writes "Here's an interesting tidbit from the NY Times on Verizon's new EV-DO network they've dubbed simply, BroadbandAccess Plan. A mere $80/mo. gets you wireless access over Verizon's 3G network at "giddy" speeds of 400-700 kbps. True, that's not exactly breakneck, compared to my 2800-3400 kbps desktop connection. But, the fact that it's hotspot-free (tetherless) wireless access from major metropolitan areas should count for something. One negative is slow upload speeds of around 100 kbps."
In this case, it has to do with spectrum and equipment. It's easy for the tower to blast out a strong signal with tons of data, and each mobile to hear it. The only limit here is spectrum allocation.
In the reverse direction, the signal from the mobile is much more tightly power-limited, so if there's too much data per unit of energy, the tower can't hear it above the noise. The solution if you can't yell, is to speak slowly.
For wireline services, it's murkier. The noise budget of a DSLAM has a few things in common with the wireless situation, but in most cases, the upload could go much faster than they sell, and yes, it's a political decision rather than a technical one. With cable, the upload is a shared channel, so they're fairly conservative in what they allocate. They should allow more upload when the network is busy, but that would take effort on their part, and only help a few percent of the customer base.
Here's what's funny: The EV-DO tower equipment is served by T1 circuits, which are symmetric. I understand using T1s for the voice stuff, since it's delay-sensitive, but they could've saved a bundle by using DSL for the data. The equipment is capable of it too, just in a nonobvious way. I bet it was never even considered.