wiki:OFDMReferenceDesign

Version 14 (modified by cjcamp, 17 years ago) (diff)

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OFDM Networking Reference Design

By default, this project creates a custom wireless ethernet link between two computers, each attached to a WARP kit (FPGA board + clock board + radio board). Each computer is unaware that a wireless link is present, and simply communicates with its neighbor using a standard wired connection. The WARP boards are "inserted" between the two computers to provide a transparent wireless bridge. The following diagram gives a simple overview of the configuration used for this example.

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If it not possible to obtain two computers, the WARP link may be inserted into the wired connection between a single computer and a DHCP server. Typically, the WARP boards will be inserted between the computer and an RJ45 jack in a laboratory or office. This configuration, while appearing to be a simpler one, may be more difficult to troubleshoot in the event that problems arise.

The WARP kits that implement the wireless link treat Ethernet packets ONLY as payload, and do not perform ANY IP processing.

Initial Setup

The following image illustrates a complete set of hardware used to implement this example. IF YOU HAVE NOT ALREADY DONE SO, NOW WOULD BE A GOOD TIME TO WORK THROUGH THE LABORATORY EXERCISE INTRODUCTION TO THE WARP FPGA BOARD. This introductory exercise provides a solid introduction to using the boards, including detailed illustrations of correct cable connections.

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Several cable connections must be made on each WARP kit before this demo may be performed:

  • a 12 V power supply connection to the FPGA board's power input,
  • an antenna connection to the "outside" antenna port of the radio board,
  • an MMCX-to-MMCX cable connected between the clock board and the radio board, and
  • a wired Ethernet connection between each WARP kit and one of the local computers,

The following images illustrate each of these connections. EXERCISE EXTREME CAUTION WHEN PLUGING A CABLE INTO THE CLOCK BOARD, AS THE INTERFACE BETWEEN IT AND THE FPGA BOARD IS EXTREMELY DELICATE! THE CLOCK BOARD SHOULD BE GRASPED FIRMLY BE THE EDGES TO PREVENT ANY ROCKING MOTION WHEN INSTALLING THE MMCX-TO-MMCX CABLE.

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The DIP switches on one WARP kit should be set to the binary value 0000. The DIP switches on the other WARP kit should be set to the value 0001. When power is applied to the WARP nodes, the value on the each board's 7-segment display should reflect its DIP switch settings -- either "0" or "1".

Example System Configuration 1

The user will need to supply two computers and two WARP nodes (1 node = 1 FPGA[v1.2] + 1 Radio[v1.4]). The computers need to be configured to have hardcoded IP addresses within each other's addressable range. In other words, they must be in each other's subnet to be able to talk to one another. For example, one computer can be 10.0.0.8 and the other can be 10.0.0.9 and each can have a subnet mask of 255.255.255.0.

One FPGA board must by configured as Node 0, and other as Node 1, using the on-board dip switches. The switch closest to the power supplies represents the node value. When the program is downloaded, the seven-segment LCDs should show the node values.

Using ethernet, connect one PC to one board, and the other PC to the other board. Note, if the PCs are using older network cards that do not support auto MDI/MDI-X, the user may need to provide crossover ethernet cables instead of standard cables. Once the boards are connected and configures, any traffic directed to one computer's IP address from the other computer will be forwarded.

Example System Configuration 2

The user will need to supply one computer and two WARP nodes. Enable DHCP on the computer (most likely already enabled, unless the user tried the first configuration).

One FPGA board must by configured as Node 0, and other as Node 1, using the on-board dip switches. The switch closest to the power supplies represents the node value. When the program is downloaded, the seven-segment LCDs should show the node values.

Connect the PC to a board using a standard or crossover ethernet cable. Connect the other board to an internet source (e.g. the wall, a router, etc). The computer will then be able to access network resources via the WARP OFDM link.

Download the full reference design here: OFDM Reference Design (60MB .zip file).