4 factors To Be Taken Into Consideration When Choosing The Right RAN Functional Split
March 15, 2024

3GPP defined the functional splits in 38.801 to formalize potential protocol split options. Functional splits are intended to allow functions to run in a central location ( ex. Data Center ) Vs. distributed in the radio heads ( ex Site Location).

RAN Functional Split (Source: Cisco)

There are 4 factors to be taken into consideration when choosing the right functional split as below:

  1. Fronthaul interface throughput and latency requirements.
    As more functionality is pushed toward a central location (lower level split), fronthaul throughput increases, and latency requirements get tighter.

  2. Implementation complexity.
    There is a benefit to a low-complexity radio head (size, weight, power, and design efforts are low) which tends to be supported with a lower level (Option 7.2x split in ORAN).

  3. Feature support.
    Centralization of processing can allow for more advanced features to be implemented such as Coordinated Multi-Point transmission and reception (CoMP).

  4. Resource sharing.
    One of the main objectives of Open RAN/Cloud RAN/C-RAN initiatives was resource pooling/sharing given the peak versus average use of RF resources.

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