ID 683238
Date 2/01/2024
Public

## 3.8. O-RAN IP U-Plane Packet Size

When you select 9000 for the Maximum Ethernet frame size, U-plane packet size in bytes for the data packet (tx_u_size) input signal is available.

When you turn on U-Plane Fragmentation, the IP updates this field.

When you turn off U-Plane Fragmentation, logic must provide the correct value to the IP (compressed packet size in bytes if Enable companding is on). You can calculate tx_u_size using this equation:

tx_u_size = Common Header + Section 1 Header + Section 1 IQ Data + Section 2 Header + Section 2 IQ Data + … + Section N Header + Section N IQ Data

where each of the field value are:

Table 34.  Field Values
Field Bytes
Section IQ Data (udCompMeth 0) (2*12*udIqWidth/8)*numPrbu
Section IQ Data (udCompMeth 1 or 3) ((2*12*udIqWidth/8)+1)*numPrbu

### Example 1

Single Section, Static Mode, Section 1 (numPrbu 1,udCompMeth 0, udIqWidth 12)
tx_u_size = Common Header + Section 1 Header + Section 1 IQ Data
tx_u_size = 4 + 4 + ((2*12*udIqWidth/8)*numPrbu)
tx_u_size = 4 + 4 + ((2*12*12/8)*1)
tx_u_size = 44 Bytes

### Example 2

Single Section, Dynamic Mode, Section 1 (numPrbu 2, udCompMeth 1, udIqWidth 14)
tx_u_size = Common Header + Section 1 Header + Section 1 IQ Data
tx_u_size = 4 + 6 + (((2*12*udIqWidth/8)+1)*numPrbu)
tx_u_size = 4 + 6 + (((2*12*14/8)+1)*2)
tx_u_size = 96 Bytes

### Example 3

Two Sections, Dynamic Mode, Section 1 (numPrbu 3, udCompMeth 1, udIqWidth 8), Section 2 (numPrbu 5, udCompMeth 0, udIqWidth 10)
tx_u_size = Common Header + Section 1 Header + Section 1 IQ Data + Section 2 Header + Section 2 IQ Data
tx_u_size = 4 + 6 + (((2*12*udIqWidth/8)+1)*numPrbu) + 6 + ((2*12*udIqWidth/8)*numPrbu)
tx_u_size = 4 + 6 + (((2*12*8/8)+1)*3) + 6 + ((2*12*10/8)*5)
tx_u_size = 241 Bytes