Filtered orthogonal frequency division multiplexing for improved 5G systems

Abstract

Wireless communications became an integrated part of the human life. Fifth generation (5G) is the modern communication which provides enhanced mobile broadband (eMBB), ultra reliable low latency communications (URLLC), and massive machine type communication (mMTC). Thus, 5G have to provide coverage to multi-numerology devices, therefore, modulation and access schemes are suggested in the literature such as cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) and filtered OFDM (f-OFDM). CP-OFDM suffers from the high out of band emission which limited the multi-numerology applications. In f-OFDM, the out of band emission can be suppressed to an accepted extent such that different numerologies can be coexisting. On the other hand, f-OFDM can be more improved by using a proper filtering approach. In this paper three different filters are suggested based windowed-sinc function; Hanning, Hamming, and Blackman. Simulation results show that the proposed filters are promising for high spectral efficiency and out of band emission rejection. Furthermore, the bit error rate, error vector magnitude, and power spectral density are further improved with respect to CP-OFDM scheme but some trade-off is present. Overall, the suggested windowed-sinc filters are outperforming the traditional CP-OFDM. As a conclusion, the suggested windnowed-sinc filters have no limitations on the modulation order or the number of subcarriers utilized in the system.

Enhanced 5G contender based flat top weighted window communication systems

“…It is feasible to integrate the function blocks shown in Figure 1 by using the settings provided in Table 3. That is, the Invers/FFT size, N, is set to 1024, the filter length, L=N/2-1, is 511-points [6], [8], [29]. Further, the constellation mapping, M, will be 256, in other words, 256-QAM.…”

“…Methods such as the windowed-sinc approach [28] are straightforward to use, methodical, and may be implemented online. As a matter of fact, this filter design approach has a number of clearly defined windows [29], [30]. This can be described mathematically as:…”

“…As a direct consequence, data throughput increases. There are several window types described in the literature [29], [30], each with its own set of pros and drawbacks. For example, the most basic type is the rectangular-window.…”

PAPR Reduction in Cyclic Prefix OFDM (5G) System using Group Codeword Shifting Technique

“…Beside that the CP-OFDM, out of band (OOB) emission is highly efficient in the time domain, resulting in the need for time and frequency synchronizations, since the OOB emission created interference with neighbor channels. Due to the fact that restrained synchronization adds additional time (latency) to the system's operation, this higher latency needs increased power consumption [27].…”

PAPR reduction in CP-OFDM (5G) using hybrid technique

“…Apart from CP-OFDM, the outof-band (OOB) emission is extremely efficient in the time domain, necessitating time, and frequency synchronisations due to interference with neighbouring channels caused by the OOB emission. Because the constrained synchronisation adds additional time (latency) to the functioning of the system, this increased latency requires increased power usage [22].…”