FCC Opens More Spectrum for WISPs

flirzan writes "Today the FCC announced that they will be opening up new spectrum for use in wireless broadband applications. The new spectrum will run from 3650-3700 Mhz, and requires that licensees register all system base stations. This is great news for wireless ISPs everywhere, as it will make interference avoidance/mitigation much easier. Licenses will run 10 years, and are renewable and transferable. No word yet on how much the licenses are expected to cost or when they'll be available."

Comments

Good Thing

[Anonymous Coward]

This is surely a good thing, WISP's are currently operating using the ISM and UNII bands with extremely low EIRP levels.

The new rules are as follows:

"Fixed stations will be allowed to operate with a peak power limit of 25 Watts per 25 megahertz bandwidth, and mobile stations with a peak power limit of 1 Watt per 25 megahertz bandwidth."

Wireless infrastructure spectrum

[_ph1ux_]

There should be several calsses of spectrum for WIFI data transit.

one spectrum range would be for station-to-station communications

one spectrum can be for user-to-station communications

one spectrum can be for user-to-user communications.

I am not a wireless engineer, so i dont know what frequencies are suitable for for what distances etc, but you should have one range for high-bandwidth medium-long range. (such as the spectrums mentioned here)

So multiple channels in a particular cell, in such a number of channels where you dont overlap channels in adjacent cells. (802.11[n])

Next you would have less bandwidth, more available channels and medium range. Finally you would have short range, medium badnwidth limited channels.... (bluetooth etc)

Re:Wireless infrastructure spectrum

[negative3]

With any wireless system the spectrum is divided in a similar way. For example, in cellular phone systems there are chunks of bandwidth set aside for control channels, the base station to mobile link, and the mobile to base station link. Often times these chunks are all fairly close to each other (within the same general band).

separating the frequency range for different applications is not necessarily a good idea - having the devices intelligently use the spectrum they see is a key issue. Also, the modulation scheme used for the data determines the bandwidth and can be changed to most efficiently ustilize the spectrum (different data rates for different links, e.g. assymetric DSL) and the channel conditions.

As far as distance goes, the general idea is that lower frequencies propagate farther (AM radio has a longer range than FM partly because of the frequencies involved). The signal strength that you see as you move away from a transmitter does not drop linearly though (proportional to 1/d^2 for free space) which means that you lose a lot of power quite quickly. Of course sending out more power will let you go a little farther, but it also helps things like bluetooth since they can be low power devices (always a good idea) and won't interfere with things fairly close to them.

Re:Wireless infrastructure spectrum

[div_2n]

I am not a wireless engineer, so i dont know what frequencies are suitable for for what distances etc, but you should have one range for high-bandwidth medium-long range. (such as the spectrums mentioned here)

To answer your question, the higher you go on the mhz chart, the more data you can push over the spectrum. Conversely, the lower you go on the mhz chart, the better you go through objects.

Of the widely used channels:

900 mhz -- low data, best for non-line of sight
2.4 ghz -- high data, sensitive to objects (water especially)
5.3 ghz -- higher data, very sensitive to objects
5.8 ghz -- even higher data, even more sensitive to objects

WISPS often already do what you suggest by using the 5 ghz spectrum for backhaul and 2.4 (and occasionally 900mhz) for client communications.

2.4ghz is becoming quite crowded. I actually expect it possible 900mhz could see a revival because it is not crowded. The only downside is that it doesn't offer much throughput.

Re:Two questions

[kebes]

For those who can't get the PDF, here it is in plain text:

FCC OPENS ACCESS TO NEW SPECTRUM FOR
WIRELESS BROADBAND IN THE 3650 MHZ BAND

WASHINGTON, D.C. - Today, the Federal Communications Commission (FCC or
Commission) adopted rules to open access to new spectrum for wireless broadband in the 3650-3700
MHz band (3650 MHz). The Commission adopted a hybrid approach that draws from both the
Commission's unlicensed and licensed regulatory models and provides for nationwide, non-exclusive
licensing of terrestrial operations in the band utilizing technologies employing contention-based
protocols. This streamlined licensing mechanism with minimal regulatory entry requirements will
encourage multiple new entrants and stimulate the rapid expansion of wireless broadband services --
especially in rural America -- by Wireless Internet Service Providers (WISPs) and other entities with
limited resources. The Commission also provided an opportunity for the introduction at 3650 MHz of a
variety of new wireless broadband technologies, such as Wi-Max, into the band.

Under the Commission's approach, there is no limit on the number of licenses that can be
granted, and each licensee will be authorized to operate on a shared basis with other licensees on all 50
megahertz of the band, subject to restrictions in geographic areas occupied by grandfathered Fixed
Satellite Service (FSS) and Federal Government stations. Licensees will also be required to register all
system base stations electronically with the Commission. Base station registration will enable licensees
to locate each other's operations and will facilitate protection of grandfathered stations from interference.
This type of licensing and registration will enable the Commission to monitor the use of this spectrum as
new technologies and services develop.

The Commission found that the public record developed in this proceeding supports multiple
users sharing this spectrum through the use of "contention-based" protocols to minimize interference
among fixed and mobile operations. New fixed and mobile stations will therefore be required to use
contention-based protocols, which will reduce the possibility of interference from co-frequency operation
by managing each station's access to spectrum. The Commission concluded that this approach is a
reasonable, cost-effective method for ensuring that multiple users can access the spectrum.

The Commission gave all licensees the mutual obligation to cooperate and avoid harmful
interference to one another. Mobile stations also will be required to positively receive and decode an
enabling signal transmitted by a base station. The Commission determined that this approach will ensure
that mobile stations operate within range of registered base stations, thereby avoiding interference to grandfathered FSS and Federal Government stations. Fixed stations will be allowed to operate with a
peak power limit of 25 Watts per 25 megahertz bandwidth, and mobile stations with a peak power limit of
1 Watt per 25 megahertz bandwidth.

The Commission kept the existing allocations for the band, grandfathering previously licensed
primary incumbent FSS earth station operations and three Federal Government radiolocation stations,
entitling them to interference protection from new wireless licensees. To protect these incumbent
operations, the Commission established circular protection zones around them - 150 km for FSS earth
stations and 80 km for Federal Government stations - and prohibited new terrestrial licensees from
operating within these zones unless they negotiate agreements with the incumbents. The Commission
determined that new FSS stations should be allowed on a secondary basis and denied several petitions for
reconsideration of an earlier decision in this proceeding that established the existing FSS, FS and MS
allocations.

The Commission also concluded that there should be no eligibility restrictions

Re:How much of the spectrum is left

[MonMotha]

For the upper bands, the local governments have quite a bit of say in how thigns are alloted due to the fact that those signals just don't go very far beyond line of sight under normal circumstances. There are some exceptions that are dictated by the ITU and the US pays attention to those. These exceptions are mostly for research quiet zones (and those are pretty small), non geo-sync sats, etc.

The HF bands (which readily propagate around the world), VHF and lower UHF (which can propagate distances significantly beyond those you would expect) have some ITU regulations attached to them. The FCC does pay attention to these international regulations of the RF spectrum.

The US also has agreements regarding allocations up in the microwave ranges along its borders with other nations to avoid interference.

Only 50 MHz of radio real estate

[G4from128k]

The total bandwidth seems small, only 50 MHz which is less than the 94 MHz of space available for 802.11b. Throw in the need for non-overlapping channels, interference, etc. and this version of wireless broadband will probably offer less bandwidth that original WiFi.

I can only hope that the higher emitted power will let service providers boost SNR (rather than space-out the antennas further) to provide more digital bandwidth within their limited radio bandwidth allotment.

Re:Two questions

[josecanuc]

1. How many WISPs will a single area be able to support, or more specifically, what will be the maximum number of WISP licensees for a given area?

There is not a limit on the number of licenses. This is a break in the usual FCC trend of limiting the nubmer of licenses given based on the number of "channels" that can be defined. They are doing this because of the requirement that users of this new band utilize technologies that would allow automatic interference remediation and channel-sharing techniques. This is how the current 2.4GHz ISM band operates.

The fact that this will be a licensed service allows for higher powers. Fixed stations are allowed 25W per 25MHz of bandwidth, and mobile stations are allowed 1W per 25MHz of bandwidth. (I like this method of power limits, because in today's world of wide-banded radio technologies, this effectively attempts to cap the signal intensity on any frequency slice rather than total output power.

2. Are there limitations on the number of WISP licenses you may hold? That is to say, would it be possible for Clear Channel or SBC or subsidiaries of either to buy up all the WISP licenses for a certain area and then just sit on them, blocking any competition from entering the market?

This question is essentially moot given that there is no limit on the number of licenses available in one geographic location and that frequencies will be shared.

I look forward to seeing how this will pan out in the consumer-gear market. 2.4GHz has been totally trashed because of the near-ubiquity of 802.11 services; a product of the unlicensed nature of the ISM band -- everyone can dump a signal out! (how's that for a runon sentence?)

If the equipment for operating in this band is kept out of the "mass retail" market, this will end up being a great thing. It's when you get a million or so average-joes who may be good to average network operators, but who don't understand squat about RF collision domains that things really start to get mucked up.

For those that don't get the joke:

[Gerad]

It's a reference to a Night Elf unit from Warcraft III, called a Wisp.

Re:Private Band

[Doc Ruby]

Actually, lots of other people have identified the specific problems this kind of licensing poses for low power apps, like WiFi mesh, that offer real local community value. Shortsighted dismissal of that conflict plays right into the hands of large corporate interests, like Intel's, which were protected by this process, despite lots of public opposition.

Re:Two questions

[R2.0]

There is another factor. FCC regulations require that licensees actually use their licenses. Once a license is awarded, the licensee must construct facilities within a certain time and begin service within a certain time after that - in total, about 2 years.

If a licensee doesn't use the frequency or hasn't constructed, the license effectively comes up for grabs on a first come-first served basis. This is called a "finder's preference," where whoever rats out the non-performing licensee to the FCC gets first dibs on the license.

As such, if someone were to buy a license and just sit on it, it would only last a short time - the license can be snatched out from underneath them.

Base stations performing local mastering functions

[Ungrounded Lightning]

The key word here is "non-exclusive"... they're not treating it as property this time, more like the the town commons. If this works the way I think it will, there will be a low fee to cover administrative overhead, just like the Amateur Radio service.

Nobody is going to pay millions of dollars to have to cooperate and share... millions are only payed when a monopoly is guaranteed.

Unfortunately, some of the protocols (like WiMAX) assign timeslots. That means somebody arbitrates the timeslots. That somebody is the base station - or the station "performing the base station role". (When you're doing a WiMAX mesh it gets more complicated...)

Notice that the FCC is licensing the base stations...

The way I read this: WiMAX base stations need to perform local mastering functions in order to assign timeslots and subchannels in their region - while WiMAX non-base stations ("subscriber stations" in WiMAX standard-ese, but think of it as "the ordinary guys") defer administrative decisions to base stations. That means that, if you set up a contention-based protocol between base stations to divvy up bandwidth-authority in their vicinities, the base stations are in a position to cheat by asking for more than their share and the subscriber stations are not.

So the FCC is requiring base stations to obtain a license. This means they can identify them and subject them to greater scrutiny. And it means they can revoke the license if they're found to be cheating, and bring charges and levy fines against any who are violating the terms of their license, as well as anyone who operates a base station without getting a license.

This doesn't hamper people who want to set up a mesh of non-"base station" peers, provided they use a contention-based protocol that defers to any licensed base stations within range. No base stations & contention based means no license required.