PRIME packets max size?

Hi Rubens,

We can hold up to 8 UNACKed MAC packets and the default SAR (segment size) is set to 64. This can be limit for the maximum size at the MAC level. If you want to send a bigger size of packets (~500 -600 bytes), I would recommend you to set the SAR size to 256 (via SET_MAC_PIB, refer to the host message spec for the PIB ID)  and then try with the size. It should work.

Regards,

Wonsoo

Hi Wonsoo,

Do you know which is the PIB ID to change the SAR size? I've been searching but I don't find in PRIME documentation the PIB ID that refers to SAR size.

Kind regards,

Rubén Sanz

Hi Ruben,

Please refer to page 22 in the attached PRIME host message spec. Thanks.

Wonsoo

PRIME_Host_Message_Specifications.pdf

Hello,

I don't know if the problem is relationship with SAR segment size because I'm sending PPDU packets without segments. The test I'm doing is a program that sends PPDU packets, each time one byte bigger; when the packet is: 371 data bytes+9 bytes generic and mac header+4 crc bytes the modem stops to send the packets, so I think that it could be a limit in the PLC modem relationship with the packet size.

Regards,

Ruben

Hi Ruben,

I may need to understand your testing environment better. How do you run the PRIME testing? Using our GUI tool or implementing your own host driver from the external host device. Are you running normal network testing with PRIME DC?

Based on your description, it seems that you are directly sending the PPDU, which means that you may run the PHY testing. In this case, any network features (such as SAR) will not be included.

The PHY length field may not include the exact byte length because the unit of length in the PHY header is OFDM symbol. The actual byte length can be extracted from the MAC header at the MAC layer. Please, refer to the PRIME spec.

Regards,

Wonsoo

Hi Wonsoo,

You’re right, I send directly the PPDU, so I’m using PHY_tx_ppdu_t data type. The problem I’ve found is when I send a MAC packet of size: 9 bytes generic and mac header+371 data payload+4 crc bytes;  the PLC modem stop to send anything else; it seems like a max limit or a bug on it. Of course the PHY length field has a valid value according to PPDU length.

Note: As PRIME spec, the max data payload length in MAC layer is 512 bytes.

Regards,

Ruben

Hello,

In the code I'm using modulation #define PHY_TX_TEST_DEFAULT_MOD PRIME_PRCL_DBPSK_F  // bpsk + fec, is it DBPSK+CC modulation?

I think it is the reason of the maximum MAC packet size I found.

Regards,

Ruben

Ruben,

You are using the PHY API and the maximum PHY size should be matter. With BPSK+CC, the maximum packet size is 377 byte per PRIME spec. You can't send more than the max size. Thanks.

Wonsoo