In the present section, we assess via computer simulations the equalization performance achieved by using the frequency-spreading structure and compare it with that achieved by the standard structure.
To this end, rotated spreading transforms have been proposed for multicarrier systems in [22] where it is shown that the often used Walsh-Hadamard codes lead to poor diversity gains when employed to perform the frequency spreading.
The reason for choosing the Vandermonde structure for the frequency spreading matrix follows that of the space spreading matrix.
We show that in the tested examples, the designed waveforms are nonorthogonal which leads to superior performance compared with that of the frequency spread LFM waveforms commonly used in the traditional MIMO radar systems.
frequency spread [23] based FBMC, featuring also a general prototype with length KM and designed using the frequency sampling approach with only 2(K−1) non-zero coefficients.
In terms of complexity, an efficient implementation of FBMC (using frequency spreading) is compared to suboptimal versions of UFMC and GFDM.
The pitch patterns, Pe[k, n], are smeared out over frequency using the level dependent spreading function.
In this paper, we have proposed an open-loop MIMO OFDM-CDMA scheme using space-time-frequency spreading (STFS), in the presence of frequency-selective Rayleigh-fading channel.
As well, the impact of noise enhancement from ZF is reduced due to the inherent property of avoiding poor channel quality using space, time and frequency spreading.
Varying this twist permits many data streams to fit in the frequency spread currently used for just one.
It is clear that our scheme has better resiliency to the frequency selectivity of the channel due to the inherent property of avoiding poor channel quality using the proposed space, time and frequency spreading.
