View of A REVIEW ON FILTERED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING FOR 5G

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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 10,October 2021 IMPACT FACTOR: 7.98 (INTERNATIONAL JOURNAL)

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A REVIEW ON FILTERED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING FOR

5G

Sanskriti Thakur M. Tech Scholar, BTIRT Sagar

Vikash Panthi

Faculty, EC Deptt, BTIRT, Sagar

Abstract - The filtered orthogonal frequency division multiplexing (F-OFDM) system has been recommended as a waveform candidate for fifth-generation (5G) communications. The suppression of out-of-band emission (OOBE) and asynchronous transmission are the distinctive features of the filtering-based waveform frameworks. Meanwhile, the high peak- to-average power ratio (PAPR) is still a challenge for the new waveform candidates. The underlying waveform has always been a shaping factor for each generation of the cellular networks, such as orthogonal frequency division multiplexing (OFDM) for the 4th generation cellular networks (4G). To meet the diversified and pronounced expectations upon the upcoming 5G cellular networks, here we present a comparative study between OFDM and F-OFDM. It is expected that for 5G F-OFDM can be a better technique. The study concludes that the F-OFDM performs better when compared with OFDM.

Keywords: OFDM, Filtered-OFDM, 5G, PAPR, OOBE, communication.

1 INTRODUCTION

Wireless communication system is a major need of the existing world. As it is well known that in such rapidly growing world, fast and efficient communication is required. Modulation is the process of converting data into radio waves by adding information to an electronic or optical carrier signal. A carrier signal is one with a steady waveform like constant height, or amplitude, and frequency.

Multicarrier modulation is a new step in the field of wireless communication to make the system faster and convenient.

Multicarrier modulation is a technique for transmitting data by sending the data over multiple carriers which are normally close spaced. Multicarrier modulation has several advantages including resilience to interference, resilience to narrow band fading and multipath effects. For fourth generation communication system OFDM was the best technology but it is not suited for 5G communication system.

F-OFDM is the one among the OFDM based candidate modulations for upcoming 5G systems. However, as in all multicarrier modulations (MCM), high PAPR is the main drawback of this modulation as the transmitted signals is the superposition of multiple independent and orthogonal sub-carriers. Lower PAPR is an essential waveform design principle for the 5G new waveforms to be capable of meeting the 5G requirements and of improving the power efficiency, so the PAPR should be reduced. It has become

imperative to have an adequate PAPR reduction technique with less computational and hardware complexity, consequently, propose a modified selective mapping using Discrete Sine Transform to lessen the PAPR of filtered-OFDM.

However, employing a single technique has disadvantages that may affect the performance of some other system parameters like Bit Error Rate, so applied the PSO algorithm that will advance the BER concert of the system.

Orthogonal Frequency Division Multiplexing (OFDM) has been the waveform of choice for 4G LTE and IEEE 802.11 WiFi based technologies. However, it still has certain drawbacks. Some of the most evident ones are high Peak-to- Average Power Ratio (PAPR), high out of band emission, and stringent synchronization requirements. Another major drawback in OFDM is that the entire bandwidth can be used only with common waveform parameters like the subcarrier spacing, cyclic prefix (CP) length and Transmission Time Interval length. Several new waveform candidates have been proposed to meet the requirements for 5G.

2 OFDM

In broadcast communications, OFDM is a kind of advanced modulation, a strategy for encoding computerized information on various transporter frequencies. OFDM has formed into a well-known plan for

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wideband advanced communication,

utilized in applications, for example, computerized TV and sound telecom, DSL web access, wireless systems, power line systems, and 4G portable interchanges.

OFDM is a frequency division multiplexing (FDM) conspire utilized as a computerized multi-carrier modulation method. In OFDM, various firmly divided orthogonal subcarrier signals with overlapping spectra are transmitted to convey information in parallel.

Demodulation depends on Fast Fourier Transform algorithms. Each subcarrier is modulated with a regular adjustment plot at a low symbol rate. This keeps up complete information rates like customary single-transporter regulation plans in a similar transfer speed.

The fundamental favorable position of OFDM over single-bearer plans is its capacity to adapt to serious channel conditions (for instance, lessening of high frequencies in a long copper wire, narrowband obstruction and recurrence specific blurring due to multipath) without complex adjustment channels.

Channel equalization is rearranged on the grounds that OFDM might be seen as utilizing numerous gradually balanced narrowband signals as opposed to one quickly regulated wideband signal. The low symbol rate utilizes a guard interval between symbols reasonable, making it conceivable to take out inter-symbol interference (ISI) and use echoes and time-spreading (in simple TV noticeable as ghosting and obscuring, separately) to accomplish a decent variety gain, for example a sign to-commotion proportion improvement. This component additionally encourages the structure of single frequency networks (SFNs) where a few adjoining transmitters impart a similar sign all the while at a similar frequency, as the signs from different far off transmitters might be re-joined usefully, saving impedance of a conventional single-bearer framework.

Fig.1 Block Diagram of OFDM Architecture

3 F-OFDM

In F-OFDM, the allocated bandwidth could be split up as many the number of sub-bands; each one sub-band is independently modulated by means of classical OFDM modulation, Sub-band- based separating is then applied to stifle the between sub-band impedance, F- OFDM additionally gives noteworthy decreases on the gatekeeper band utilization, prompting progressively effective range usage. It is the augmentation of the exemplary OFDM with an extra sub-band channel and adaptability in changing the parameters like transmission time interval, length of cyclic prefix, and subcarrier spacing. The filter bandwidth is planned for an assured sub-band, but it is avoidably equal to 1 PRB. In this way, Filtered OFDM is proficient of surmount the drawbacks of OFDM while keep hold of the reward of it.

Simplified F-OFDM system model is shown in Fig. 2. Compared with the traditional OFDM system, F-OFDM will be the whole frequency band is divided into multiple sub-bands, the sub-band filter is added in transmitter and receiver. Each sub-band set different waveform parameters according to business scenarios demands, the parameters such as the subcarrier spacing, length of CP, FFT points, etc. The transmitter of each sub-bands data through the subcarrier number after mapped to different subcarrier, and the sub-band filter for filtering and inhibition of adjacent interference with frequency spectrum leakage. The receiver by match filter is used to implement each sub-band data of decoupling. In LTE system, Quadrature amplitude modulation (QAM) is used and here we also use QAM with different modulation orders. IFFT is performed on the modulated signal to make it into

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OFDM symbol and N is the IFFT/FFT size.

CP is added to avoid inter-symbol interference caused by the delay spread of wireless channels [11], while the CP size

varies with the different communication scenarios. The filter f (n) is the digital filter which can use different kinds of window functions to achieve F-OFDM.

Fig. 2: Block Diagram of F-OFDM Architecture 4 IMPORORTANCE OF 5G

As we all know that 5G is faster than 4G in all attributes. There are so many important applications ans advantages of 5G over the conventional communication technology. Some uses are discussed here as follows:

i. High-speed mobile network: 5G is an advancement on all the previous mobile network technologies, which offers very high speed downloading speeds 0 of up to 10 to 20 Gbps. The 5G wireless network works as a fiber optic internet connection. 5G is different from all the conventional mobile transmission technologies, and it offers both voice and high- speed data connectivity efficiently.

ii. Entertainment and multimedia: In one analysis in 2015, it was found that more than 50 percent of mobile internet traffic was used for video downloading. This trend will surely increase in the future, which will make video streaming more common. 5G will offer High-speed streaming of 4K videos with crystal clear audio, and it will make a high definition virtual world on your mobile.

iii. Internet of Things—connecting everything: the 5G mobile network plays a significant role in developing the Internet of Things (IoT). IoT will connect many things with the internet like appliances, sensors, devices, objects, and applications.

These applications will collect lots of data from different devices and sensors.

iv. Healthcare and mission-critical applications: 5G technology will bring modernization in medicine

where doctors and practitioners can perform advanced medical procedures. The 5G network will provide connectivity between all classrooms, so attending seminars and lectures will be easier. Through 5G technology, patients can connect with doctors and take their advice.

Scientists are building smart medical devices which can help people with chronic medical conditions.

v. Satellite Internet: In many remote areas, ground base stations are not available, so 5G will play a crucial role in providing connectivity in such areas. The 5G network will provide connectivity using satellite systems, and the satellite system uses a constellation of multiple small satellites to provide connectivity in urban and rural areas across the world.

5 CONCLUSION

The work study of OFDM and Filtered OFDM has been carried out. It is concluded that OFDM is well suited for 4^th generation communication. As there is a big amount of OOBE leakage in OFDM and hence it can’t perform as per the expectation in 5G. For 5^th generation communications an alternative candidate is needed. Here in this study it is found that Filtered OFDM can be a fit modulation technique to full fill the requirements of 5G criteria. The need of lower latency and asynchronous connectivity is also achievable by F- OFDM. Hence, it can be concluded that F- OFDM can be a better choice for 5th generation of mobile communication systems.

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