Aerial testbed/DGX Spark: some cubb parameter

Accelerated Computing Aerial Forum
1

Hi Aerial team,

when checking the yaml, I found that
for foxcon ru

      fs_offset_dl: 15
      exponent_dl: 4
      fs_offset_ul: -5
      exponent_ul: 4

for wnc ru

      fs_offset_dl: 7
      exponent_dl: 4
      fs_offset_ul: -5
      exponent_ul: 4

I had some quesion:

  1. how to calculate the fs_offset. when in RU the dl/ul fs_offset for bfp is both 0, the DU side shall configure as 0 too?
  2. exponent_dl/exponent_ul is the addition for bfp exponent? e.g. the expoonent after bfp is 9, after addition, it become 9+4=13
2

The definition of these parameters is written in the O-RAN CUS specification. If O-RUs fully comply with the specification, these values match with O-RUs’ configuration (O-RUs usually have the same parameters). Some O-RUs have different implementations. These values are results of our tests.
BTW, WNC O-RUs have a mode for an O-RAN specification compliant mode. With this mode, you can set fs_offset_dl/ul to 0.

For the exponent, it is also the same definition with the O-RAN specification. For BFP9, it’s 4.

3

thanks @nhashimoto ,

In the CUS spec, exponent is defined as:
Common exponent for compressed PRB and 4bits in packet

but I still can’t understand below parameters according to the spec
exponent_dl: 4
exponent_ul: 4

4

My explanation was insufficient, sorry. It’s the bit length of the exponent field. It’s not a value of the exponent field.

5

thanks @nhashimoto

Why aerial need to define a parameter which is fixed to 4 in CUS spec?

6

4-bit is commonly used in the market, but it is a parameter. Please refer to the M-plane specification.

7

thank @nhashimoto your response in weekend!