If you’ve ever delved into OFDM systems, you know that Cyclic Prefix (CP) is a critical feature.
The CP is a small but powerful addition - a redundant overhead added at the beginning of each OFDM symbol. By copying the last part of the symbol, CP may seem like it reduces spectral efficiency, but it brings incredible benefits:
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Resilience to Delay Spread: A CP length of about 5xRMS delay spread can effectively combat inter-symbol interference (ISI), ensuring robust data transmission in multipath environments.
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Simplified Equalisation: By converting linear to circular convolution, CP allows for simplified equalisation with a single-tap FIR filter.
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Prevents Inter-Block Interference: It maintains the orthogonality of OFDM symbols, preserving data integrity over complex channels.
I recently got a fresh perspective about CP in a webinar by Christopher Hansen on 802.11/Wi-Fi channel estimation - highly recommend!
Inspiration for graphics:
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