WARP Project Forums - Wireless Open-Access Research Platform

1. Basically i think the Ethernet packet is the payload part of my packet. When it is passed to the MAC layer, MAC adds a MAC header to my packet. Then the MAC header + payload is treated as payload when passed down to PHY layer. Phy layer adds PHY header to my packet. When the packet is transmitted, preamble and training symbols are added before the packet. I think base rate is modulating the packet header and full rate is modulating the packet payload.

there is a structure "Macframe"（structure "phyHeader"  and  "remainingTx"） in warpmac.h. Is structure "Macframe" like a MAC Header or PHY Header?


2. OFDM Design used a 24 Bytes Header, it means structure "phyHeader" is 24 Bytes? and how can i find the bytes for each field in the header (length, srcAddr, destAddr and so on...... )?

i think 2 Bytes for "short int" Type and 1 Byte for "char" Type, right?



3.  i want to find the different between the warp frame format and the general Mac frame format,

here is the general Mac frame format in 802.11:
Byte:            2                          2                        6                    6                 6                          2                            6                   0 - 2312                 4
          Frame control     |     Ruration ID     |     Address1   |   Address2   |  Address3   |   Sequnece  Control   |      Address4    |      Frame Body    |      CRC     |
          <----------------------------------------------------------------------MAC Header--------------------------------------------------->


so i think the warp frame format is something like below, am i right?:

fullRate    |   codeRate   |   length   |   srcAddr    |  destAddr    |    relAddr    |     pktType   |    seqNum    |    Reserved byte 1-10     |    checksum    |     remainingTx   |    plus ethernet paket   |
<----------------------------------------------------------------------------------PHY Header------------------------------------------------------------------------->
<----------------------------------------------------------------------------------MAC Header---------------------------------------------------------------------------------------------->

4. i use iperf to send udp from one node to another:   iperf -u -c 10.0.0.2
i printf the txframe.header.length in code csmamac.c. i find the result on terminal is 1516, but when i use the wireshark, the frame is 1512, there is always 4 Bytes less than in Terminal (it happens again when i use ping to test).

and sometimes when i use some packet sending tools (D-ITG) to set the payload to 1472 (max. payload ), it always fail to do it. the max payload which allow me to set is 1468 Bytes, so these is another 4 Bytes less. could you please tell me why?

Thanks!