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Hi
I am trying to do Video transmission with warp v3 OFDM reference design_v18p1. My idea is that VLC is responsible for encoding and multiplexing video streams, MIMO-OFDM modulation, demodulation, space-time coding are completed by the FPGA. The antenna mode used in the SDK is "warpphy_setAntennaMode (TX_ANTMODE_MULTPLX, RX_ANTMODE_MULTPLX)", the source rate setted to "txFrame.header.codeRate = HDR_CODE_RATE_34" and encoding format is "Video for MPEG4 720p TV / device". The result is that receiver often appears a large green image. I would like to ask, this antennas' co-frequency interference are relatively large or MPEG4 compression rate is too high? In addition, I also tried MPEG1, the effect is still not ideal.
Thanks a lot!
Last edited by BOb (2016-Dec-30 04:39:11)
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BOb wrote:
I would like to ask, this antennas' co-frequency interference are relatively large or MPEG4 compression rate is too high?
A good debugging step is decouple the video from the wireless side of things. Use a tool like iperf to characterize your wireless link independently of any video encoding/decoding issues with VLC. Then run some experiments between laptops directly connected with Ethernet to see what kind of bandwidth various video settings require. With those two independent sets of measurements, you can choose video parameters that should be able to be carried by the wireless link.
Finally, I want to just mention that the OFDM Reference Design is no longer being developed and last had any substantive update many years ago. The modern Mango 802.11 Reference Design for WARPv3 vastly outperforms the OFDM Reference Design in addition to being standards compliant. One caveat to this is that the 802.11 design is currently SISO-only. That said, I'm confident that even with a single antenna it outperforms the OFDM Reference Design in its MIMO mode.
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I consider the source distortion and channel distortion will affect the quality of video transmission. At the transmitter, the higher the compression rate, the greater the distortion of the source; at the receiver, the quality of the received image is poor, due to compression rate of MPEG4(VLC)is too high?
I would like to do some research about MIMO. If the "warp v3 OFDM reference design_v18p1" is not appropriate ，not considering the real-time data processing, I can only modify the MATLAB code to achieve streaming data transmission with "wl_example_mimo_ofdm_txrx.m" in the WARPLAB? Pcore's buffer, agc, trigger all need to be amended or just one of them? I am a newcomer to WARP.
Thank you for your reply!!
Last edited by BOb (2016-Dec-30 23:13:08)
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I would like to do some research about MIMO. If the "warp v3 OFDM reference design_v18p1" is not appropriate ，not considering the real-time data processing, I can only modify the MATLAB code to achieve streaming data transmission with "wl_example_mimo_ofdm_txrx.m" in the WARPLAB?
You'll have to be more specific about your project's requirements. WARPLab is the best place to start for designing MIMO waveforms and MIMO signal processing. The WARPLab Reference Design enables rapid prototyping of waveform-level processing without any custom FPGA design. The ref design supports 2-radio and 4-radio nodes by default.
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