This paper evaluates the performance of an uplink OFDM-based communication system considering multipath propagation environment where a Massive MIMO approach is exploited. In this context, Zero Forcing detector is used and assessed. Numerical analysis of the mathematical model was conducted on MATLAB. The results presented in this paper include Bit Error rate (BER) and the channel capacity of QPSK/OFDM transmission through a fading channel. Performance results verify the positive effect of Massive MIMO even when reduced complexity detection technique is used.
PL
Analizowano właściwości systemu komunikacyjnego bazującego na OFDM. Uwzględniono wielostrumieniowy rozsył z eksploatacja dużego MIMO. Opracowano model matematyczny I przeprowadzono symulację określającą BER I pojemność kanału dla przesyłu QPSK/OFDM.
The potential use of typical commercial communication systems with ultra high frequencies for the underground emergency/military situations will be investigated, as commercial systems have already a fully developed market that makes them cheap and reliable. The possible usage of broadband techniques like CDMA in the direct sequence will be studied because most commercial communication systems have already been designed to support multiple users, as the underground propagation has many possible applications. The performances of both modulation techniques are evaluated from the point of view of the quality of the signals, power spectral density and the effect that the propagation medium has on the transmitted signals such that the best modulation technique is determined. The 16QAM and QPSK modulations (two of the most popular modulation techniques in the terrestrial wireless system) are compared in a scenario where a number of underground sources share the same physical channel (and antenna) - the receiver is placed at the ground level so the generated signals must propagate through the dielectric layer in order to reach it. The transmitted power, electric and magnetic fields as well as occupied bandwidth are also calculated.
Orthogonal frequency division multiplexing (OFDM) provides better spectral efficiency than frequency division multiplexing (FDM), while maintaining orthogonal relation between carriers; hence traffic is better carried by OFDM than FDM within the same spectrum. This paper reveals a comparison of spectral efficiency, performance of communication system in context of bit error rate (BER) for the same information rate and peak to average power ratio (PAPR) of quadrature amplitude shift keying (QPSK) and 16-quadrature amplitude modulation (16-QAM) technique.
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