Understanding SSB Frequency Location and ARFCN Configuration for Band 47 (V2X) in 5G

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Hello everyone,

I’m currently working on configuring a Distributed Unit (DU) for band 47 (V2X), specifically in the frequency range of [5855 – 5925] MHz. I’m using the OpenAirInterface configuration, and I need to update the configuration file to support band 47, as it originally only provides support for band 78. The configuration file in question can be found here: [DU Configuration File - OpenAirInterface]

I understand the concept of SSB and the overall cell search process in 5G. However, I’m facing challenges with the specifics of SSB frequency location, particularly in choosing the correct Absolute Radio Frequency Channel Number (ARFCN) and/or Global Synchronization Channel Number (GSCN), as well as determining the frequency point A (dl_absoluteFrequencyPointA) and the SSB absolute frequency (absoluteFrequencySSB).

Could anyone share insights or guidance on:

  • How to accurately select the ARFCN and/or GSCN (code bellow) for band 47?
  • The methodology or considerations for identifying/choosing the correct frequency point A and SSB absolute frequency in practice?

I’m seeking detailed technical advice to ensure the DU is correctly configured for optimal performance and compliance with band 47 specifications. Any examples, references, or personal experiences with similar configurations would be greatly appreciated.

Here is the band 47 entry for GSCN configuration I made:

// synchronization raster per band tables (Rel.15)
// (38.101-1 Table 5.4.3.3-1 and 38.101-2 Table 5.4.3.3-1)
// band nb, sub-carrier spacing index, Range of gscn (First, Step size, Last)
const sync_raster_t sync_raster[] = {
  {1, 0, 5279, 1, 5419}, {2, 0, 4829, 1, 4969}, {3, 0, 4517, 1, 4693}, {5, 0, 2177, 1, 2230},
  {5, 1, 2183, 1, 2224}, {7, 0, 6554, 1, 6718}, {8, 0, 2318, 1, 2395}, {12, 0, 1828, 1, 1858},
  {20, 0, 1982, 1, 2047}, {25, 0, 4829, 1, 4981}, {28, 0, 1901, 1, 2002}, {34, 0, 5030, 1, 5056},
  {38, 0, 6431, 1, 6544}, {39, 0, 4706, 1, 4795}, {40, 1, 5762, 1, 5989}, {41, 0, 6246, 3, 6717},
  {41, 1, 6252, 3, 6714}, {47, 1, 9482, 1, 9527}, {48, 1, 7884, 1, 7982}, {50, 0, 3584, 1, 3787},
  {51, 0, 3572, 1, 3574}, {66, 0, 5279, 1, 5494}, {66, 1, 5285, 1, 5488}, {70, 0, 4993, 1, 5044},
  {71, 0, 1547, 1, 1624}, {74, 0, 3692, 1, 3790}, {75, 0, 3584, 1, 3787}, {76, 0, 3572, 1, 3574},
  {77, 1, 7711, 1, 8329}, {78, 1, 7711, 1, 8051}, {79, 1, 8480, 16, 8880}, {257, 3, 22388, 1, 22558},
  {257, 4, 22390, 2, 22556}, {258, 3, 22257, 1, 22443}, {258, 4, 22258, 2, 22442}, {260, 3, 22995, 1, 23166},
  {260, 4, 22996, 2, 23164}, {261, 3, 22446, 1, 22492}, {261, 4, 22446, 2, 22490},
};

Configuration file: [DU Configuration File - OpenAirInterface]

Thank you in advance for your assistance and looking forward to your valuable insights!