News

Transforming the 2.5 GHz Band April 24, 2018 13:57

On April 19th, the FCC opened a docket to collect comments related to "Transforming the 2.5 GHz Band".  As background, the US 2.5GHz spectrum band encompasses 33 channels.  20 channels (A, B, C, D, and G groups) are designated for Educational Broadcast Service (EBS) and 13 (BRS1/2, E, F, and H) are designated for Broadband Radio Service (BRS).  

License Area:

Sprint owns a vast majority of the BRS licenses and leases a vast majority of the EBS licenses.  The licensing limitations for this spectrum are drawn from its origins providing broadcast video services.  The original licenses were formed as 35 mile radius circles centered on the video transmitting site.  When two licenses overlapped, a football shaped area would be formed.  A line would be drawn through the end points of the "football" splitting the overlapping license area between the two licensees.  BRS licenses include both 35 mile radius licenses, geographic area licenses (entire BTA) and Entire BTA license with cutouts for existing 35 mile radius licenses.

In 2009, a Broadband Radio Service auction (Auction 86) included the remaining unlicensed areas within each BTA for the BRS channels, but the unlicensed area in each BTA for the EBS channels was not auctioned.

Channel Plan Transition:

Prior to this point, Clearwire was launching pre-WiMax networks on the EBS/BRS pre-transition band plan which was designed around video operation.  As you can see in the Pre-Transition chart below, the A channels (A1, A2, A3, and A4) are separated by the B channels (B1, B2, B3, and B4).  This allowed all of the A channels to be broadcast at a video site without interference.  Clearwire would need to control both sets of the "interleaved" channels to have enough contiguous spectrum to launch their RAN network in a market.

To facilitate data network deployments and to protect the remaining video operations the FCC provided a way to transistion licenses to the Post-Transition band plan on a BTA market basis.  If there was a significant commercial video operation in a market, that BTA market was able waived from transition and it stayed with the Pre-Transition band plan.  The Post-Transition band plan put the remaining video operators into the mid-band segment (A4, B4, C4, D4, G4, F4, and E4) and provides contiguous spectrum (16.5MHz) for the rest of the channel group (e.g. A1, A2, and A3)

FCC Request for Comments:

License Area:

The FCC has expressed a desire to make the EBS unlicensed area available for use.  The FCC has asked whether the expansion of the licenses should include the entirety of the census tracks that license (35 mile) intersects or the entire county that the license intersects.  The map below from the National EBS Association (NEBSA) illustrates the counties that would be added to each intersecting EBS license for the A1 channel.  For the carriers that already lease these licenses, they would have the opportunity to deploy sites on the larger license area and would likely also pay the licensee a higher monthly payment due to the increase in licensed population.   As you can also note below, this approach still leaves all of the white counties unlicensed.

 The FCC would like to license the white counties in a 4 step manner:

  1. Existing licenses could extend their license areas to the borders of the counties they currently intersect but there may be requirements on how much of each county you must already cover.
  2. Rural tribal nations can apply for licenses covering their local area.  License areas could be census tracks or counties.
  3. Accredited schools or governmental entities can apply for their local area licenses.  License areas could be census tracks or counties.
  4. Auction remaining unlicensed area with competitive bidding.

Service Rules:

The FCC is also proposing to change the service rules for the EBS spectrum to allow the spectrum to be sold to commercial operators rather than requiring leases.

Remaining Pre-transition Markets:

The FCC is also proposing to complete transitioning the remaining pre-transition markets so a consistent band plan would be in use nationwide.  A few wireless cable operators had received waivers but most of those operators have ceased operations.  This will clear interference issues between markets and facilitate the deployment of data in the Lower Band Segment (A,B,C, and D groups) and the Upper Band Segment (E,F,G, and H groups).  Video operations will continue in the Mid Band Segment (A4, B4, C4, D4,G4,F4, and E4) in the markets where they operate today.


Google's Experimental Network - Mountain View, CA January 24, 2013 09:44

There is a little buzz this morning about an application from Google to construct a experimental network on 2.5GHz frequencies on the Mountain View, CA campus.  Here is a link to the application.  The application states that they will be using spectrum between 2.524 and 2.546GHz and between 2.567 and 2.625GHz.  The top issues with this application is that Clearwire operates their WiMax network within this market and has states on their earnings calls that they typically deploy using between 30MHz and 60MHz of spectrum.  Google would need to guarantee that there would be no harmful effect to this commercial network.  Now lets look at the specific spectrum allocations.


In the above image from my Spectrum Ownership Landscape Report, you can see that the lower band matches correctly to the B2, B3, C1, and C2 channels.  The upper band matches the LTE Band 38 so there would appear to be a desire to test TDD-LTE equipment in that portion of the band.

Can Google do this without Clearwire's agreement and assistance?  I don't think so.  The B2,B3 channels are owned by The Santa Clara Board of Education (Call Sign WHG338) and don't appear to be leased to Clearwire so they are ok.  C1,C2 (Call Sign WHR466) are owned by The Assocation for Continuing Education and they appear to be leased to Clearwire.  The spectrum in Band 38 is particularly interesting.  First of all, it is the portion of the spectrum that is currently dedicated to video operation, so Google would need to work with each of the broadcasters and convince them that their operation in Mountain View would not interfer with the ability of the broadcaster's clients to receive their desire video broadcast.  In addition, the presence of this high powered video interference would make Google's tests much more challenging, especially outdoors. On the far right of the spectrum allocation Google has requested is the BRS2 channel that is clearly owned by Clearwire.

For the video spectrum, Clearwire still holds the leases for the A4, C4, D4, E4, and F4 channels.  I anticipate that Clearwire is not supportive of this testing without their involvement and they will protest the experimental authorization.  In my history with with wireless carriers, it was not unusual to see a experimental application for my carrier's spectrum without being contacted directly for the use of my carrier's spectrum.

Globalstar - Terrestrial Low-Power Service (TLPS) January 22, 2013 12:22

Globalstar's Proposed Terrestrial Low-Power Service (TLPS) has some well thought-out approaches.  Globalstar has petitioned the FCC to allow them to utilize their 2484-2500 MHz "Big Leo" satellite spectrum to provide terrestrial coverage.
Globalstar's spectrum lies directly above the 2.4GHz ISM band which hosts a vast majority of the WiFi in use today, as well as bluetooth and microwave ovens.  Directly above the Globalstar spectrum is the EBS/BRS spectrum controlled primarily by Clearwire.

Globalstar has proposed terrestrial operation on a the newly named AWS5 band.  It would essentially be a 4th non-overlapping WiFi channel (Channels 1,6,and 11 are the primary non-overlapping WiFi channels).  It would still be a 22MHz wide channel, using the ISM band above Channel 11 (which is lightly used) and about 10MHz of their AWS5 channel.  Globalstar believes that most existing WiFi devices could support this spectrum with a over-the-air software updates so a massive number of devices could be overloaded to this network once it is constructed.

Also intriguing is the improved performance characteristics of this spectrum.  First, since it is licensed to Globalstar, they can control the use of the spectrum.  They envision a carrier grade network using this spectrum that would manage Hotspot power levels and interference.  Since this spectrum has much less interference, it is capable of covering larger areas with higher speeds than typical WiFi.

If Globalstar can figure out the backhaul aspect to providing this service, I think they will have a leg up on other white-glove WiFi service providers since they are better able to manage the RF environment for their frequencies. It is conceivable that Globalstar would host WiFi overloading for all of the 4 national carriers.  I still see the biggest challenge to be in a residential environment where they envision a hotspot in my house being under their control, but likely on my cable internet service.  I'm pretty sure Comcast won't react well to my residential internet service supporting a commercial operation.

Is this a service that could be considered or expanded into the EBS/BRS channels that are adjacent to Globalstar's spectrum?  The answer is yes.  Clearwire has stated that they have excess spectrum.  I would anticipate that this would look like a private LTE network on Clearwire's spectrum versus WiFi on Globalstar's, but it would not be as feasible as Globalstar's proposal due to the current lack of devices that support LTE on the EBS/BRS frequencies.



DISH Counter-Offer for Clearwire January 09, 2013 10:34

Dish's counter-offer for Clearwire is intriguing.  I recently completed a presentation detailing the challenges of a spectrum sale in the EBS/BRS spectrum.  Clearwire's press release states that this offer was on the table when Sprint's offer was received but Sprint's offer was deemed better.  Tim Farrar's Blog indicates that the spectrum sale would likely be for Clearwire's BRS spectrum.  This is a realistic assumption.  In my presentation (linked in a previous blog) I highlighted that one of the primary problems with the leased spectrum is that it has limited geographic coverage, covering many of the dense metro areas but not contiguous all the way to a county or BTA border.  There are still a few elements of a BRS spectrum sale that should be understood.


From the image above, the BRS spectrum sale would include the Orange (BRS1/BRS2) channels, the Pink (E channels), Light Blue (F channels) and Brown (H channels). This would equate to one contiguous block of 55.5MHz of spectrum, a 12MHz block of spectrum (E4,F4), and the isolated BRS1 channel.  The 12MHz block could only be used if mid-band video operations have ceased in a market.  Currently, I don't believe that any of the Top 10 markets have completed ceased video operations.  The 55MHz of spectrum can support 2 - 20MHz TDD-LTE channels.  This would virtually eliminate the ability to utilize the EBS/BRS spectrum for any FDD-LTE operations.  It may be possible with a guardband in the H channels to operate the D channels and G channels in a FDD-LTE configuration.

In looking at the LTE Bandplans, the potential Dish spectrum allocation would miss the international TDD-LTE Band 38 which Softbank, China Mobile, and the UK auctions are using.  We will have to watch carefully to see if international devices will include functionality of Band 41.

My last area of concern is whether that will leave enough spectrum for Clearwire to continue to operate their WiMax network as they bring their TDD-LTE network online.  Additionally, with the geographic limitations of the leased channels, there may be a limited number of sites operating on Clearwire's network today, that won't have available spectrum without the owned channel spectrum.

Webcast: Clearwire's Spectrum Explained January 08, 2013 13:27


Below is a link to an Investor's Presentation provided by AllNet Labs detailing the licensing, geographic, and leased versus owned challenges of Clearwire's Spectrum.

Audio and Slide Presentation

Presentation Outline

Agenda

  • History of the EBS/BRS Spectrum
  • Owned versus Leased Spectrum
  • LTE Band Configuration
  • Recent Auctions
  • Substantial Service
  • Issues before the FCC
  • Spectrum Sale Challenges

Why Couldn't Clearwire Sell Their Spectrum? December 18, 2012 10:28

Another area of interest from the Sprint / Clearwire conference call yesterday were Erik Prusch's comments related to Clearwire's attempts to sell spectrum in 2010.  Erik indicated that the offers they received were below value.

I will be conducting a webinar for GLG Research on January 4, 2013 where I will be discussing the history and challenges of Educational Broadcast Service (EBS) and Broadband Radio Service (BRS) spectrum.  I believe that the undervalue offers were due to issues with the spectrum channelization, geographic boundaries, unlicensed channels, and FCC mandated obligations for leased spectrum.

What is wrong with Spectrum Pricing? December 04, 2012 19:23

Clearly the wireless industry has locked in spectrum pricing with the MHz-POP pricing model, but is this the right way to look at it as we move into a 4G World where data throughput and capacity are key?  For those that aren't familiar, the typical value of spectrum is determined by the $/MHzPOP which is the dollars spent for the spectrum divided by the total amount of spectrum times population that spectrum covers.  This model falls short now as carriers are interested in acquiring larger contiguous blocks of spectrum enabling higher users speeds and more capacity.

To use a real estate analogue, a large plot of land is much for flexible for multiple uses, than two plots, even if they are in the same neighborhood.  In real estate, the developer that is able to consolidate several tracks of land into a larger development is rewarded as he sells the larger development.

In the wireless industry, we continue to price based upon the $/MHz POP basis, even as carriers such as T-Mobile and Clearwire have combined adjacent channels to create larger bands of spectrum to utilize in larger LTE channels.  T-Mobile has worked this year with Verizon, SpectrumCo, and MetroPCS which will allow it to assimilate a 2X20MHz LTE channel on a national basis.  Clearwire has leased and purchased operators in the BRS and EBS spectrum bands providing it with an average of 160MHz of spectrum in the top markets.  Since Clearwire's spectrum has many geographical boundaries, it is difficult to say how many 20MHz channels they could support across each of their markets, but they have been successful consolidating small bands of spectrum into larger more flexible spectrum bands.

How does a larger band of spectrum affect the wireless carriers?  In the US, carriers have deployed FDD-LTE in 1.25MHz channels, 5MHz channels, and 10MHz channels.  As you increase the channel size throughput performance improves because a lower percentage of the data packets are dedicated to overhead activities   Qualcomm has provided achievable LTE Peak Data Rates for different channel bandwidths based upon whether the antennas are 2x2 or 4x4 MIMO.

Link to Qualcomm Document



As you can see in the 4x4 MIMO downlink case, the throughput is 12Mbps greater in the 20MHz channel than the composite of 4-5MHz channels.

So if a  20MHz channel is 4% more efficient than 4 - 5MHz channels should the MHz POPs pricing adjust accordingly?

By the way.. I am going to look for more source data on the capacity improvements for wider channels, a 4% improvement would seem to be relatively negligible.  I recall hearing 30% improvements in capacity when a channel size is doubled, but I haven't been able to re-source that data for this blog.   More to come.