Implementation and performance evaluation of MIMO GFDM systems

• Autor(a) principal: Kassam, Joumana
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/29616
• topic: 5G; Beyond 5G; Modulation schemes; GFDM; MIMO; Interference Cancellation techniques

The Orthogonal Frequency Division Multiplexing (OFDM) technology has been used in 4G and 5G mobile telecommunications systems. Despite its features and advanced results, it has some challenges to enhance spectral efficiency. Generalized Frequency Division Multiplexing (GFDM) is a new digital non-orthogonal multicarrier modulation concept. It aims to achieve higher spectral efficiency, better control of Out-Of-Band (OOB) emissions due to its flexibility to choose the pulse shaping filter, and obtain a reduction in Peak to Average Power Ratio (PAPR) compared to the OFDM. MIMO can further improve the spectral efficiency of the wireless network and has adopted in several standards. Therefore, the combination of MIMO transmission with GFDM technique is almost able to present optimum results due to its ability to have diversity gain by combining independent signals from multiple antennas in order to mitigate the fading phenomenon. Besides, it can also achieve multiplexing gain that improves the throughput of the networks. This study addresses the implementation and evaluation of a GFDM system for different antenna structures such as SISO, SIMO, and MIMO. First, SISO-GFDM system is implemented, considering Additive White Gaussian Noise (AWGN) channel and Rayleigh fading channel. Several frequency domain equalizers are used to mitigate the fading and remove the residual Inter-Carrier Interference (ICI) such as Matched Filter (MF) and Zero Forcing (ZF) equalizers. Then, the system was extended to SIMO and Multi-User MIMO (MU-MIMO), where a set of single-antenna users transmit to the base station, equipped with a multi-antenna array, using the same radio resources. In MU-MIMO system besides the ICI, it also suffers from multi-user interference. Therefore, in this case, two sub-optimal receiver equalizers have been implemented to deal with both ICI and multi-user interferences such as (ZF and MMSE equalizer). The GFDM system is compared with the OFDM in terms of bit error rate (BER) and power spectral density. The results show that the Interference Cancellation (IC) techniques (Serial Interference Cancellation (SIC) and Double Sided Serial Interference Cancellation (DSSIC)) are quite efficient to mitigate both the multi-user interference and the adjacent ICI, improving the overall system performance.