Electrical & Electronics Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/44

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Browsing by Institution Author "AGHDAM, Mohammad Reza Ghavidel"

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    Eliminating intrinsic interference in GFDM systems: Design of a complex-valued prototype filter
    (Elsevier, 2024-04) Aghdam, Mohammad Reza Ghavidel; Mozaffari Tazehkand, B.; Abdolee, R.; Electrical & Electronics Engineering; AGHDAM, Mohammad Reza Ghavidel
    Prototype filter design is a critical challenge in generalized frequency division multiplexing (GFDM) systems. Poorly designed filters can result in inherent and out-of-band (OOB) interferences, severely impacting system performance. This paper proposes a novel solution to this problem by introducing an optimal prototype filter that mitigates the adverse effects of intrinsic interferences in GFDM systems. Our approach involves using a complex-valued prototype filter, which resembles a single-sideband (SSB) modulation scheme and significantly enhances bandwidth efficiency compared to conventional GFDM. To design the optimal filter, we formulate an optimization problem that eliminates inband and adjacent subcarriers intrinsic interferences. We also provide analytical expressions for evaluating the system's bit error rate (BER) and demonstrate the superiority of our optimized prototype filter over its current counterparts. To validate the design of the proposed prototype filter, we assess the noise enhancement factor (NEF). Our results indicate that our proposed filter improves system performance and reduces BER in GFDM systems.
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    Low-complexity interference reduction for gfdm systems using corrective coefficients
    (IEEE, 2022) Jirdehi, A. A.; Abdolee, R.; Tazehkand, B. M.; Aghdam, Mohammad Reza Ghavidel; Electrical & Electronics Engineering; AGHDAM, Mohammad Reza Ghavidel
    Generalized Frequency Division Multiplexing (GFDM) is a promising multi-carrier modulation scheme for next-generation wireless communication systems. GFDM uses a non-orthogonal pulse shape, which leads to self-interference among sub-carriers. In this paper, we propose a new coded GFDM method to reduce the self-interference in each block by using a space-frequency block coding (SFBC) scheme. To this end, we introduce corrective coefficients based on channel state information and the demodulation matrix for each modulated data. We evaluate the bit error rate (BER) performance of the system by comparing SFBC-GFDM transmission in Rayleigh channels with a matched filter (MF) receiver. Our computer simulations show that the proposed scheme substantially improves the system performance in BER. Per our results presented in this paper, we achieve 5 dB performance improvement at BER of 10-2 compared to previous counterparts.
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    Out-of-band analysis of GFDM systems based on different self-interference types
    (IEEE, 2023) Aghdam, Mohammad Reza Ghavidel; Abdolee, R.; Tazehkand, B. M.; Jirdehi, A. A.; Electrical & Electronics Engineering; AGHDAM, Mohammad Reza Ghavidel
    This paper studies the impact of out-of-band (OOB) emission and interferences on the generalized frequency division multiplexing (GFDM) systems. Specifically, we analyze the effects of two types of independent self-interference, namely inband and adjacent subcarrier interference, on the OOB performance. We analytically derive mathematical expressions for OOB emission and sufficient conditions for reducing OOB. We investigate the effects of different prototype filters on the OOB performance based on the new formulation of the GFDM system. Our numerical experiments show that the OOB performance is independent of the modulation order and depends on the type of prototype filter and its orthogonality.