Sprint's Use of the 2.5GHz Guard Bands for TDD-LTE February 11, 2019 07:30

Late last year Sprint, filed some renewal applications that provided some insights into how they are configuring their 2.5 GHz spectrum assets for 20 MHz TDD-LTE channels.  As a reminder, the US 2.5 GHz band is configured into an Lower Band Segment (LBS), Mid Band Segment (MBS), and Upper Band Segment (UBS).  In the graphic below each of the segments are delineated by the J guard band and the K guard band. 

The LBS is to the left of the J channel, the MBS is between the J and K channels, and the UBS is to the right of the K channel.  The purpose of these guard bands was to provide protection to the data services originally offered in the LBS and UBS from the continuing video operations in the MBS.

It is a lesser known fact, that the all of the LBS spectrum owners collectively own the 4 MHz J channel and the UBS spectrum owners collectively own the 4 MHz K channel.  The J and K channels are licensed as secondary use, meaning they can be used accepting any interference from remaining video systems (primary use) operating in the MBS.

In our February 2019 release of the Mobile Carrier - Spectrum Ownership Analysis Tool,  we have have expanded the detail in our Spectrum Grid for these guard band channels along with the proper licensing database records.  

As you can see in the above image, the J channel breaks down into 12 sub-blocks of 0.3 MHz each.  The first sub-block (JA1) is controlled by the owner of the A1 channel.  The second sub-block is controlled by the A2 channel owner.  So this update provides a clear view of whether Sprint controls the sub-blocks that would allow them to operate a 20 MHz channel across either guard band.  Because the use of these spectrum is secondary, we don't include these spectrum blocks in EBS/BRS spectrum totals, and MHz-POPs totals in our tools.

Now onto Sprint's recent renewal application.  Sprint's original application requested Special Temporary Authority (STA) to allow Sprint to use the KG1, KG2, and KG3 channels in 15 BTA markets where the G123 channels are still held by the FCC as unlicensed white space.

In the image above, you can see that in the counties surrounding Atlanta, the FCC controls the G123 channels. This limits Sprint's TDD-LTE deployment to 2-20 MHz channels, indicated by the black boxes.

With the STA, Sprint can utilize the KG1, KG2, and KG3 channels allowing them to form an additional 20 MHz LTE channel by combining the F4, E4, K, and BRS2 channels.

The image below is from Sprint's original filing.  It illustrates the geographic area of the Atlanta BTA and an indication where the G1 channel is licensed, where it is leased to Sprint, and where it is FCC white space.  The areas in gray that do not intersect the red or yellow areas are the FCC white spaces where Sprint has requested access to the KG1, KG2, and KG3 channels.  Sprint did not request access to the primary G1, G2,or G3 whitespace licenses (16.5MHz total).