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About the 3650 MHz Band
Learn More About the 3650–3700 Radio Service

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FCC 15-47 Amendment

The FCC allocated 50 MHz of spectrum in the 3650–3700 MHz range for terrestrial wireless broadband service regulated under FCC Part 90 rules. Licensees may provide a broad range of new products and services, including high-speed, wireless local area networks and broadband Internet access. The Commission adopted a flexible and innovative regulatory framework for the 3650–3700 MHz band that would not require traditional frequency coordination among users with the exception of incumbent Fixed Satellite Service Licensees (FSS) and Federal Government Radiolocation stations. However, the licensees must deploy equipment that uses “contention-based protocols” and share the obligation to cooperate to avoid harmful interference with other licensees. A license for the 3650–3700 MHz Radio Service consists of a non-exclusive nationwide license, followed by fixed and base station registration in the FCC’s ULS.

Here are the steps involved in obtaining authority to operate:

  1. Understand the FCC rules (Report & Order, MO&O, Filing Procedures PN)
  2. Obtain a one-time license (which is nationwide by default) through the ULS
  3. Examine ULS or Comsearch’s free search tool for other nearby 3650 MHz systems
  4. Identify grandfathered earth stations and Federal radiolocation station protection zones using Comsearch’s free search tool or view them on a map
  5. Obtain FCC-certified equipment
  6. Register each fixed and base station in the ULS
Step 3 of the process involves locating other 3650 MHz licensees with registered equipment in your area by searching ULS or Comsearch’s free search tool. Since there is no “first come first served” rights for the band, new entrants would need to contact the licensee(s) to discuss coordination to avoid interference. Searching for other licensees in your area should be done frequently even after you deploy, since new operators are permitted to enter after you.

Step 4 of the process involves protection of grandfathered, incumbent stations from interference. There are two types of grandfathered, incumbent stations that new 3650 MHz band licensees must protect: non-Federal grandfathered earth stations and Federal radiolocation stations. For the 86 non-Federal grandfathered earth stations, the protected zone is 150 km. Licensees may locate base stations within these protected zones only after obtaining an agreement from the earth station licensee through frequency coordination negotiations. For the three grandfathered Federal radiolocation stations, the protected zone is 80 km, and locating base stations within these zones requires approval of NTIA via coordination through the FCC.

Step 5 requires the use of equipment approved by the FCC for use in this band. This equipment must use a “contention-based protocol” to recognize other systems and adjust operating parameters to minimize interference. Additionally, there are two types of certified equipment, “restricted” and “unrestricted.” A restricted contention protocol means that the equipment can adjust to minimize interference with other devices using the same or similar protocol. Restricted contention protocols are only allowed in the lower 25 MHz portion of the band (3650–3675 MHz). Equipment with an unrestricted contention protocol can operate within the entire 50 MHz of the band, but must function to adjust and minimize interference with devices using other dissimilar protocols that could be of completely different technologies.

In addition to these in-band systems, there are several thousand licensed and unlicensed C-band satellite earth stations operating in the upper adjacent band (3700–4200 MHz). Calculations show that should conditions align in a worst-case manner, separation distances of 1 km or more may be required to avoid interference into these adjacent-band receive stations. The FCC left open the possibility of requiring lower out-of-band emissions for 3650–3700 MHz transmitters shown to be the cause of interference into C-band earth stations. Additional filtering may have to be added to earth station LNBs to mitigate this oversaturation issue.

It is a fairly easy process to verify the locations of existing earth stations and determine the proximity to your planned facilities. Depending upon the interference geometry and the operating characteristics of both systems, there may be several inexpensive options available to reduce the potential for interference. It is advisable to identify potential problems and resolve them early in the process and prior to a significant capital outlay on infrastructure.

Lastly, there are several high-power radar systems operating in the lower adjacent bands. These radar systems are mostly for coastal navigation. It is important to be aware of them since there is a potential for interference to 3650 MHz systems.

Click here to access Comsearch’s free search tool! Our tool will identify nearby 3650 MHz systems, co-channel and adjacent channel earth stations, and federal radio location stations all in one easy search.

The service rules for this band fall under CFR, Part 90 and the radio service code is NN. Filing for nationwide licenses and registration began on November 15, 2007.

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