Non-Coherent Capacity of M-ary DCSK Modulation System over Multipath Rayleigh Fading Channels

Non-coherent capacity bounds for the M-ary differential chaos shift keying (DCSK) modulation system are derived and analyzed over multipath Rayleigh fading channels, deriving conditions on the channel state information/non-channel state information (CSI/NonCSI) and soft-decision/hard-decision (SD/HD), respectively. Meanwhile, the inter-symbol interference is modeled and analyzed mathematically. Through numerical simulations and analyses, it is found that: 1) the influences of the spreading factor ß , multipath number L, modulation dimension M, CSI/NonCSI, and SD/HD on the non-coherent capacity bounds are significant; 2) there is a relatively broad range of code rates corresponding to the optimal system power in U-shaped capacity curves of the non-coherent reception; and 3) the U-shaped non-coherent capacity bounds are proven to exist by investigating the mechanism of the low density parity check coded the M-ary DCSK system. These results are useful as benchmarks for designing power-efficient coded M-ary DCSK systems.