1 of 8

Security Programmable Metamaterial Antenna for Physical Layer Security

Week 9:

Prachi Patel and Dylan Turner

2 of 8

Introductions:

Dylan Turner

Prachi Patel

Goal Recap:

USRP Experiments:

Goal: Transmit and receive an OFDM signal using the B205 Mini-i USRP

Wired Connection

Antenna

Synchronization Dilema:

Received OFDM Signal

“Correlation” vs. Time

Transmitted Packet Content

One big issue we ran into during the week was synchronization. Before we get into the issues we faced, i’ll explain how this generally works. �
When an OFDM signal is transmitted, it is important that the receiver can identify where the packet starts.

Even a few samples delay in when the receiver starts decoding could cause it to dump the entire packet.

Broadly, this works by sending two sync words at the start of the packet. The receiver performs a kind of correlation between the incoming signals and the sync words. When the correlation reaches a peak, it knows that it has received the sync words.

As you can see in this graph (gesture to the autocorrelation graph), this correlation metric gives us a clear reflection of where the packet starts. Additionally, because of the cyclic prefix, we have some wiggle room.

Issues with Header/Payload Demux:

Goals for Next Week:

Questions?