Orthogonal Generalized Frequency Division Multiplexing (OGFDM)
This thesis focuses on introducing a novel technique of the transmission waveform termed as orthogonal generalized frequency division multiplexing (OGFDM) for increasing the wireless channel capacity without the need for extra bandwidth (BW) size or power consumption. The new wireless waveform (OGFDM) tends to obtain a better BW efficiency which in turn can increase highly the wireless channel capacity in comparison with the generalized frequency division multiplexing (GFDM) and cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM). The main feature of the OGFDM is developing the physical layer of future mobile networks by achieving the orthogonality between non-orthogonal filters, removing the interference between adjacent frequency subcarriers, and gaining a flexible bit loading scheme. Since the key downsides of the 4G waveform (CP-OFDM), several alternative transmission waveforms have been investigated for improving transmission techniques of the upcoming communication networks (5G and beyond). This, as a result, comes up with introducing the GFDM as the best candidate waveform for the 5G air interface. Nevertheless, due to ignoring the orthogonality with the GFDM, the BW efficiency is severely affected which in turn causes in extremely reducing the gained channel capacity (research gap). For this reason, the proposed OGFDM waveform aims to improve wireless channel capacity by investigating different levels of processing and carrier schemes. As such, three key levels called as filtration level, oversampling level, and modulation level are adopted for a variant range of OGFDM carriers like a single carrier, couple carrier, quadruple carrier, and multi-carrier system. Regarding the single carrier OGFDM system where the filtration level is developed, the orthogonality is attained between the non-orthogonal filters of the GFDM frequency subcarriers. The core idea behind this novel technique is increasing the efficiency of the applied BW which in turn can double the capacity of the channel at the acceptable level of the bit error rate (BER). Concerning the couple carrier OGFDM system where the oversampling level is developed, the double oversampling mode is applied side by side with the normal one. As a result, the OGFDM waveform can efficiently avoid the interference between adjacent frequency subcarriers improving the quality of service under bad transmission states. As regards the quadruple carrier OGFDM system where the modulation level is improved, a flexible modulation scheme is utilized rather than the fixed modulation formats. Consequently, multilevel modulation shapes are optimally assigned to gain an enhanced channel capacity in accordance with the realistic transmission state. To achieve a higher BW efficiency, the preliminary multi-carrier system that combines the three levels of processing in one uniformed physical platform is introduced. To demonstrate the main advantages of OGFDM waveform, the multicarrier system is further extended and compared with the GFDM (5G technology) and CP-OFDM (LTE Ericsson technology). Hence, the multi-carrier OGFDM can double, boost, and yet maximize the bit-rate of the transmission relative to the GFDM and CP-OFDM at the acceptable level of the BER. The MATLAB simulation and Visio tools are utilized to validate the results and represent them graphically.
OGFDM, GFDM, OFDM, LTE, Wireless Waveforms, 5G Mobile Networks, Physical Layer
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