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

Abstract

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 β, 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.

Keywords

• Non-coherent capacity
• soft/hard-decision (SD/HD)
• channel state information/non-channel state information (CSI/NonCSI)
• inter-symbol interference (ISI)