Abstract
Future wireless communication systems are demanding a more flexible physical layer. GFDM is a block filtered multicarrier modulation scheme proposed to add multiple degrees of freedom and to cover other waveforms in a single framework. In this paper, GFDM modulation and demodulation is presented as a frequency-domain circular convolution, allowing for a reduction of the implementation complexity when MF, ZF and MMSE filters are employed as linear demodulators. The frequency-domain circular convolution shows that the DFT used in the GFDM signal generation can be seen as a precoding operation. This new point-of-view opens the possibility to use other unitary transforms, further increasing the GFDM flexibility and covering a wider set of applications. The following three precoding transforms are considered in this paper to illustrate the benefits of precoded GFDM: (i) Walsh Hadamard Transform; (ii) CAZAC transform and; (iii) Discrete Hartley Transform. The PAPR and symbol error rate of these three unitary transform combined with GFDM are analyzed as well.
Highlights
Fifth generation (5G) networks will face new challenges that will require a higher level of flexibility from the physical layer (PHY). 3D and 4k video will push the throughput and spectral efficiency
7 Conclusions This paper introduces a Generalized Frequency Division Multiplexing (GFDM) modulator and demodulator based on a low-complexity multiplication in the time domain
The new matrix model allows to consider the coefficients transmitted by the subcarriers as the precoding of the data symbols
Summary
Fifth generation (5G) networks will face new challenges that will require a higher level of flexibility from the physical layer (PHY). 3D and 4k video will push the throughput and spectral efficiency. The investigation in this paper reveals that the Poisson summation formula [8] can be utilized in the demodulation process, considering a per-subsymbol circular convolution and decimation in the frequency domain. This operation can be performed as an element-wise multiplication with subsequent simple M-fold accumulation in the time domain. It is worth mentioning that the proposed low complexity signal processing complements the work in [4] because the requirement for block alignment is loosened It can be usable for supporting pipeline inner receiver implementations, when building synchronization and channel estimation circuits for embedded training sequences [12, 13].
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