Terminology » RF Basics » Licensed vs Unlicensed Frequency Bands: Key Differences

Licensed vs Unlicensed Frequency Bands: Key Differences

licensed spectrum unlicensed spectrum frequency band wireless communication spectrum management

This page compares licensed and unlicensed bands, highlighting the major differences between them. Unlicensed bands are also referred to as “license-exempt” bands.

Introduction

Systems operating within both licensed and unlicensed bands adhere to national or regional regulations. Cellular systems typically follow 3GPP technical specifications. However, in unlicensed or license-exempt bands, local variations are more common.

In the USA, the FCC defines regulations for unlicensed bands, such as the 902 to 928 MHz and 2400 to 2483.5 MHz bands. In Europe, ETSI publishes standards for unlicensed bands, including the 863 to 870 MHz and 2400 to 2483.5 MHz bands.

Licensed Band

  • A license is required to use the spectrum, and it is not free. Spectrum is purchased from governing bodies in each country.
  • The medium can only be accessed or used by the license holder (e.g., a Mobile Network Operator - MNO).
  • Access to the medium is controlled via scheduling. Permission is required for both transmission and reception.
  • Interference management is achieved through careful frequency planning.
  • Advantages:
    • Predictable interference levels.
    • Potential for Quality of Service (QoS) guarantees.
  • Disadvantages:
    • High costs for network operators due to spectrum license fees.
    • The licensed spectrum might not be fully utilized all the time.
    • Requires centralized management.
    • Lower scalability compared to unlicensed bands.
  • Examples (licensed frequency bands): 700 MHz, 800 MHz, 1.8 GHz, 2.6 GHz, 3.5 GHz, etc.
  • Examples (Systems): GSM, UMTS, LTE, TV broadcasting, Military communications, etc.

Unlicensed Band

  • Use of the spectrum is free (license-exempt).
  • Anyone can use the unlicensed spectrum and its medium.
  • Anyone can access the medium by “listening” to see if the channel is free before transmitting.
  • Interference management is implemented using techniques like “listen before talk” (LBT), “good neighbor behavior,” and distributed management.
  • Advantages:
    • Free or low cost to use.
    • Available in many locations.
    • Scalable.
  • Disadvantages:
    • Unpredictable interference due to the lack of guaranteed QoS.
    • Potentially higher network load.
    • Lack of protection from interference caused by other systems.
  • Examples (Unlicensed frequency bands): 2.4 GHz, 5.8 GHz, 60 GHz.
  • Examples (Systems): Wi-Fi, Bluetooth, LAA (Licensed Assisted Access), etc.