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ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING Peer Reviewed and Refereed Journal, ISSN NO. 2456-1037

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Vol. 06, Issue 07,July 2021 IMPACT FACTOR: 7.98 (INTERNATIONAL JOURNAL)

92

A REVIEW ON UNIVERSAL FILTERED MULTI-CARRIER MODULATION TECHNIQUE

Sonam Rathore M. Tech Scholar, BTIRT Sagar

Mr. Naveen Khare

Asstt. Prof. EC Deptt, BTIRT Sagar

Abstract - This paper describes a study over 5G technologies. Universal Filtered Multi- Carrier is a novel multi-carrier transmission technique that aims to replace the OFDM modulation technique for fifth generation wireless communication systems. This paper describes the aspects of Universal Filtered Multi-Carrier system and highlights the merits of new modulation method for emerging fifth generation Wireless Communication Systems.

Orthogonal Frequency Division Multiplexing is an excellent choice for fourth generation.

Side band leakage is another problem in OFDM. Our current 4G systems rely on the OFDM waveform, which is not capable of supporting the diverse applications 5G will offer. The traffic generated by 5G is expected to have very different characteristics and requirements when compared to current wireless technology. As result other multiple access schemes are being investigated. The way to overcome the known limitations of OFDM is UFMC technique. BER of UFMC system is less for 4QAM mapping method when compared to the other mapping methods but PAPR of UFMC is high when compared with OFDM. It is noted in the study of UFMC that for 5^th generation communication system this modulation technique may be a revolution in the whole communication world.

1 INTRODUCTION

4G communication systems such as LTE/LTE Advanced, Wi-Fi uses OFDM, as multi-carrier modulation technique.

Although it has efficient implementation and robustness to channel delays as highlights but this method suffers from high PAPR results low efficiency of power amplifier, increases the battery consumption. Moreover the OFDM spectrum has high out of band side lobes causing problem of low spectral efficiency.

To overcome some of these drawbacks new modulation techniques for 5G communication system are considered.

The applications which use 5G communication system require higher data rates, lower latency and efficient spectrum usage. The way to overcome the known limitations of OFDM is UFMC technique. UFMC is generalization of Filtered OFDM and FBMC modulations.

In OFDM the total band is filtered and in Filter Bank Multi-Carrier (FBMC) individual subcarriers are filtered where as a group of subcarriers (sub bands) are filtered in UFMC. Single carrier modulation uses one carrier to transmit overall data. This technique is widely used in GSM, CDMA 2000. The main goals to prefer this method are battery power and coverage extensions. Single carrier method requires equalizers to achieve high spectral efficiency.

Multicarrier modulation converts a

wideband carrier into multiple orthogonal narrowband carriers. For higher data transmission wireless communication systems required to incorporate Multicarrier modulation.

UFMC is considered one of the best and original multicarrier modulation methods for 5G and it is based on FBMC and OFDM. In this scheme, a filtering process is carried out on a group of subcarriers in contrast to self- subcarrier modulation in FBMC. The filter-length compared with the FBMC is reduced by subcarrier grouping and the modulation time is also reduced. The UFMC transmitter block diagram is demonstrated in fig. 3. In this scheme, the total bandwidth is initially disseminated into a number of sub-bands and is allocated to the number of subcarriers. Each sub-band has k subcarriers. The time-domain of the signal is changed to a frequency domain at the transmitter by the N-point IFFT operation. UFMC is the method that combines the advantages of OFDM and filter bank in FBMC. Instead of filtering each carrier individually like in FBMC, a block of carriers called sub-band is filtered. Each sub-band contains a number of carriers; filter length will be depending upon the width of sub-band.

In the UFMC system, the data symbols are converted to parallel stream, resulting

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ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING Peer Reviewed and Refereed Journal, ISSN NO. 2456-1037

93

in blocks of streams and given as input to

the IFFT block which transforms the input from frequency domain to time domain. The N point IFFT output will be serialized block-wise and the output will be filtered with a pulse shaping filter of length L. Finally, the filtered signals are combined together to form the transmitted signal.

1.1 UFMC Trans-Receiving System The UFMC transmitter block diagram is demonstrated in fig. 3. In this scheme, the total bandwidth is initially disseminated into a number of sub-bands and is allocated to the number of subcarriers. Each sub-band has k subcarriers. The time-domain of the signal is changed to a frequency domain at the transmitter by the N-point IFFT operation. IFFT action confirms that the sub-band carriers don’t interfere

Fig. 1 UFMC transmitter block diagram The UFMC receiver block diagram is demonstrated in fig. 2. The information that is received from the channel is given to the sequential to parallel converter and furthermore 2N point FFT is performed by the UFMC receiver on the information to demodulate it. A guard interim of zeros is included between progressive IFFT streams. And hence due to Transmitter filter delay, the Inter-Symbol-Interference (ISI) is prevented.

Fig. 2: UFMC receiver block diagram

2 LITERATURE SURVEY

A novel hybrid PAPR reduction technique CC-UFMC for UFMC signals is studied [1]. Multiple companding methods were used and each was combined with clipping technique. Simulation results and analysis shows that the hybrid scheme is an efficient PAPR reduction technique for UFMC systems, and it can provide better PAPR reduction performance than the conventional companding and clipping schemes individually, for all applied companding methods. Moreover, it was shown through comparison that the proposed scheme has a greater PAPR reduction efficiency than other techniques that were proposed to solve the high PAPR level problem.

Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation technique, which is used as a dominant waveform for the 4G communication systems. But OFDM cannot meet the demands in 5G.

Universal filtered multicarrier (UFMC) has been paid more attention in the 5G communication system because of its low out of band emission (OOBE) and compatibility for multiple input multiple output (MIMO) communication. In this paper performance of UFMC is analyzed in terms of power spectral density (PSD), Bit error rate (BER) and peak to average power ratio (PAPR). Extensive comparison of UFMC and OFDM is included to illustrate the advantages of UFMC. PAPR performance of UFMC is evaluated for various design parameters including FFT size and side lobe attenuation [2].

The performance of UFMC signals is better than OFDM in terms of side lobe attenuation, BER for discrete narrow band networks. Smart Gradient Project Active Constellation Extension (ACE- SGP), Tone Reservation (TR) methods are used to reduce the PAPR values for FBMC/OQAM signals. UFMC does not have to use a cyclic prefix, although it can be used to improve the inter symbol interference (ISI) protection using special or unified structure of the frame [5].

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ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING Peer Reviewed and Refereed Journal, ISSN NO. 2456-1037

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3 SOME UFMC v/s OFDM RESULTS

Fig. 3: PSD of UFMC and OFDM Comparison of Power spectral density of UFMC and OFDM is shown in Fig. 3. It is apparent from the figure that UFMC has less OOBE than OFDM. With UFMC OOBE improves by 50dB. High OOBE in OFDM is because OFDM uses rectangular pulse in time domain. Fig. 4 shows comparison SNR versus BER plot UFMC and OFDM for 4-QAM modulation scheme in AWGN channel. BER graph can also be plotted for 16-QAM modulation. BER performance of UFMC is almost same as that of OFDM for the entire modulation scheme. As the modulation order increases spectral efficiency increases but BER performance decreases. From the graph it is clear that even though CP is not used in UFMC BER performance of UFMC is same as that of OFDM.

Fig. 4: BER vs SNR comparison of UFMC and OFDM

4 CONCLUSION

In general study of UFMC modulation technique it is concluded that UFMC is promising waveform candidate for 5G.

The way to overcome the known limitations of OFDM is UFMC technique.

In this paper our finding shed towards 5G technique and specially UFMC performance. UFMC is the better waveform candidate for 5G communication because it has better

spectral efficiency than OFDM and FBMC. QAM modulation used in UFMC makes it compatible with MIMO transmission. In this work fair comparison of UFMC and OFDM is made under a common frame work. BER performance of UFMC is almost same as that of OFDM. PAPR of UFMC is less than OFDM. Therefore UFMC waveform is expected to be used for asynchronous transmission in 5G cellular networks. The overall band in UFMC is distributed into sub-bands. As the total number of subcarriers that are added up in phase will be less in UFMC the most extreme power diminishes in UFMC and this results in better PAPR for UFMC.

REFERENCES

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