Signal processing is not my area of expertise so need help with implementing an OFDM system.
EDIT: The cabling and uncontrolled topology already exists and need a system that re-uses existing installation in large buildings
- System is for wired communication on a shielded twisted pair. The topology is a combination of daisy-chaining, star-connections at the nodes which further go onto more daisy-chaining. Essentially as bad as power lines but largely interference free because of shielding and differential signalling.
- Bandwidth is best kept as low as possible considering very long cable runs (half a kilometer) between nodes.
- Need to be able to send up to 256kbps.
Have been reading up on OFDM from an implementation point of view. I now understand a a bit about the use IFFT/FFT to inject and extract data out of the orthogonal carriers. Need for guard intervals, frame synchronization with pilot symbols, channel estimation with pilot careers etc. Things are still coming together in my head but I have a very basic understanding of OFDM. I have some questions:
- This being baseband is there a way of not having to use quadrature mixing to transmit the Real and Complex parts of the IFFT i.e. non-passband way of sending it?
- I am trying to keep the demodulation part as simple as possible. Anyway I can get away with not using channel estimation i.e. non-coherent demodulation with DPSK or something similar?
- Any pointers to fully implemented systems that I can dissect to learn more?
- Considering the low data rate, I'll probably end up doing this on a low-end DSP.
EDIT: There is only one differential pair in the cable. The bus will have 12 to 15 nodes on it with any-to-any communication.