Delay between STA and AP communication in TCP vs UDP

[Md Ashiqur Rahman]

Hello! I am simulating a wireless scenario with a grid topology of AP-s and have 1 mobile STA moving around the grid. I have tested the simulation with both TCP and UDP application that downloads files. Seeing from the pcap files of both TCP and UDP, I see that after the association with the AP, there is a delay before exchanging packets:

TCP: packet transfer starts after about 3 seconds.

UDP: packet transfer starts after about 1 second.

I could not find an explanation why TCP has this larger delay? Could this be due to the handshake in TCP?

P.S. I don't have DHCP in my simulation and manually set STA IP upon in range of an AP. Attached are my pcaps of the 1 STA node for both tcp and udp.

Regards-

Ashiq