EVERYONE needs to be thinking of more spectrum efficient technologies, not to mention more responsible use. I've seen some proposals for channelizing 800 MHz into 12.5 kHz centers, like NPSPAC, but really, rebanding made a big enough disaster out of 800. These additional channel centers, like 12.5 and 6.25 won't work if the adjacents don't narrowband to conform in their channelspace. There are also a lot of systems that have achieved 9.6 kbps equivalency within a 20 kHz channel for 19.2 kbps data.I installed an 800MHz NexEdge trunked system about 2 years ago. It's set up for narrow band. The analog 800MHz repeater we put in as a backup system was also set up as narrow band, even though it would do 25KHz channels. FCC and NPSPAC doesn't require 800MHz systems to be narrow band, but the writing is on the wall. Anyone installing new equipment should be thinking ahead.
Watch out, TETRA's coming. Some big systems going in up in the northeast. And, why not? it's only a known, working 4/TDMA (unlike the other 4/TDMA that seems to be plagued by "issues" everywhere it's been turned up).
Quarterwave - businesses are coordinated differently. They are more based on loading, so you will see several licensees with overlapping coverage and maybe even within the same community. It's more based on loading and there is no "protection" as there might be with public safety. No matter, because the FCC always defaults to anything that's within VHF and UHF and not FB8 as "shared use."
Jay911 - well, the segregation seems to work, but some areas have a large number of licensees who have migrated off LMR to cellular. Initially they moved to Nextel and then to other platforms. So, many business frequencies lie fallow. I believe IC protects service area for each of it's licensees. I'm still trying to figure out how they work. I am involved in several "HIA" objections that would have been workable solutions based on how spectrum is reused here, but because of the treaty, a minuscule amount of energy in a 50 km radius blocks using the entire frequency at any level above 5 W ERP and secondary status.