What is Sub-6 GHz[FR1] in 5G?

 In 5G, Sub-6 GHz (often referred to as FR1, or Frequency Range 1) refers to the spectrum of frequencies below 6 GHz that are used for 5G networks. Here’s a detailed overview of Sub-6/FR1 in the context of 5G:

1. What is Sub-6 GHz (FR1) in 5G?

• Sub-6 GHz, also known as FR1, includes frequencies from 450 MHz up to 6 GHz.
• It’s the lower-frequency spectrum range used in 5G, as opposed to FR2, which includes millimeter-wave (mmWave) frequencies from 24 GHz to 52 GHz.
• Sub-6 GHz encompasses frequencies that are widely used in many countries for initial 5G deployments, with bands like 3.5 GHz (also called C-band) being popular for 5G services.

2. Characteristics of Sub-6 GHz (FR1) Spectrum

• Longer Range: Sub-6 GHz frequencies can cover a larger geographic area, as they experience lower propagation losses than the higher frequencies in the mmWave range.
• Better Indoor Penetration: Compared to mmWave, Sub-6 GHz signals penetrate buildings and other obstacles more effectively.
• Moderate Speeds: While Sub-6 offers higher speeds than 4G, its speeds are generally lower than what can be achieved with mmWave. Typical Sub-6 5G speeds range from 100 Mbps up to 1 Gbps, depending on the network conditions and bandwidth.
• Wide Area Coverage: Due to its range and penetration characteristics, Sub-6 GHz is suitable for providing broader 5G coverage over large urban, suburban, and rural areas.

3. Common Sub-6 GHz Frequency Bands in 5G

• 3.3 - 3.8 GHz (C-band): One of the primary 5G bands in many regions; balances range, capacity, and speed effectively.
• 2.5 GHz: Often used in the U.S. and some other markets for 5G.
• 600 MHz and 700 MHz: Low-band frequencies used for broader 5G coverage, especially in rural and suburban areas.
• 4.9 GHz: Another option in some countries, although less commonly used than C-band.

4. Advantages of Sub-6 GHz (FR1)

• Wider Coverage and Better Building Penetration: Makes it suitable for broader coverage across urban, suburban, and rural areas.
• More Practical for Mobile Use: Compared to mmWave, which is highly directional and short-range, Sub-6 GHz is more practical for typical mobile usage.
• Fast Deployment: Many operators can deploy Sub-6 5G quickly because it can use spectrum repurposed from other services or new bands allocated by regulators.

5. Limitations of Sub-6 GHz (FR1)

• Limited Bandwidth: Because it is lower frequency, there is less available bandwidth compared to mmWave, meaning it has lower maximum speeds.
• Lower Capacity: Sub-6 GHz cannot support as many simultaneous users as mmWave, which may limit performance in very densely populated areas.

6. Use Cases for Sub-6 GHz (FR1)

• Mobile Broadband: Enhanced mobile broadband (eMBB) services for consumers, such as faster internet and improved video streaming.
• Smart Cities and IoT: Due to its coverage characteristics, Sub-6 GHz is suitable for IoT deployments across cities and large areas.
• Urban, Suburban, and Rural Coverage: Provides essential 5G coverage in various environments where mmWave may be impractical.
  
  
  For FR2:
  https://5gfundamentals.blogspot.com/2024/11/what-is-mmwave-fr2-in-5g.html