OFDM Reference Design - CSMA Link

This application uses the OFDM Reference Design to build a wired-to-wireless bridge implementing the CSMA MAC protocol for the over-the-air link. It utilizes two WARP nodes, each connected via Ethernet to a separate PC. Every packet received on the WARP node's Ethernet interface is transmitted over the air, addressed to the other WARP node. Every packet received over the air is copied to the node's Ethernet interface. This bridging "tricks" the two PCs into believing they are connected directly over Ethernet. This application implements the same basic function as the Bridge application, but uses a more sophisticated protocol for wireless medium access.

Requirements

• 2 WARP SISO or MIMO kits (analog board in slot 4 optional)
• 2 PCs with Ethernet interfaces

Setup

1. Set the DIP switches on the WARP nodes to 0 and 1
2. Connect each WARP node directly to the Ethernet interface of the PCs
3. Configure the PC Ethernet interfaces with IP address on the same subnet (10.0.0.1 and 10.0.0.2, for example)
4. Generate the FPGA configuration file for the design using the OFDM Reference Design project and the CSMAMAC source code
5. Configure both WARP nodes using the same download.bit
6. When it's working, the PCs will be able to ping each other, stream video (using VLC, for example), or any other point-to-point network application

Code

The code for this application is provided in csmaMac.c. The default OFDM Reference Design project includes CSMAMAC as a software project.