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MERITS OF FBMC AND UFMC OVER OFDM: A REVIEW
Ravindra Chaudhary M.Tech. Scholar, JEC Jabalpur
Prashant Kumar Jain Prof.Deptt. of EC, JEC Jabalpur
ABSTRACT
This paper portrays the parts of Universal Filtered Multi-Carrier (UFMC) and Filter Base Multi- Carrier (FBMC) system and features the benefits of new modulation techniques for rising fifth generation Wireless Communication Systems.
Orthogonal Frequency Division Multiplexing (OFDM) is a magnificent decision for 4G. some limitations are there with the 4G communication technologies.
UFMC and FBMC are solutions for those limitations like, PAPR, SNR and BER. 4G modulation techniques experience the ill effects of the issue of high PAPR.
Side band lobe is another issue in4G communication system utilizing OFDM. Current 4G framework depends on the OFDM waveform, which is not equipped for supporting the various applications. The traffic produced by 5G is relied upon to have altogether different qualities and prerequisites when compared with current wireless technology. As result other different access plans are being explored. The best
approach to conquer the known restrictions of OFDM is Multicarrier techniques. UFMC and FBMC are the techniques, which overcomes the limitations of OFDM communication systems.It is noted that UFMC and FBMC performs better in 5G communication system.
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.
2 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.
1.1 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 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. The presentation of a gatekeeper interval, giving better orthogonality in transmission channels influenced by multipath propagation.Each subcarrier (signal) is modulated with a regular
adjustment plot, (for example, quadrature adequacy balance or stage move scratching) at a low symbol rate. This keeps up complete information rates like customary single-transporter regulation plans in a similar transfer speed.
The fundamental favourable 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 guardinterval 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
3 from different far off transmitters might be re-joined usefully, saving
impedance of a conventional single-bearer framework.
Fig.1: Block Diagram of OFDM 1.2 UFMC
UFMC is a speculation of Filtered OFDM and FBMC (Filter Bank Multi-bearer) modulations. The whole band is filtered in separated OFDM and individual subcarriers are filtered in FBMC, while gatherings of subcarriers (sub- groups) are filtered in UFMC.
This subcarrier gathering permits one to diminish the filter length (when compared with FBMC).
Additionally, UFMC can in any case use QAM as it holds the complex orthogonality (when compared with FBMC), which works with existing MIMO plans.
The full band of subcarriers (N) is isolated into sub-groups. Each
sub-band has a fixed number of subcarriers and not all sub-groups should be utilized for a given transmission. A N-point IFFT for each sub-band is registered, embedding zeros for the unallocated transporters. Each sub-band is sifted by a channel of length L, and the reactions from the diverse sub-groups are added.
The separating is done to lessen the out-of-band otherworldly outflows. Various channels per sub-band can be applied, in any case, right now, same channel is utilized for each sub-band. A Chebyshev window with parameterized side-flap weakening is utilized to filter the IFFT yield per sub-band
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Fig.2: Block Diagram of UFMC transmitter The sub-band filtering extends
the receive time window to the next power-of-two length for the FFT operation. Every alternate frequency value corresponds to a subcarrier main lobe. In
typical scenarios, per- subcarrier equalization is used for equalizing the joint effect of the channel and the sub-band filtering.
Fig.3: Block Diagram of UFMC receiver 1.3 FBMC
FBMC filters each subcarrier modulated sign in a multicarrier framework. The model channel is the one utilized for the zero frequency carrier and is the reason for the other subcarrier filters. The filters are described by the overlapping factor, K which is the quantity of multicarrier symbols that overlap in the time domain.
The model filter request can be picked as 2*K-1 where K = 2, 3, or 4 and is chosen according to the PHYDYAS project.
The current FBMC usage utilizes frequency spreading. It utilizes a N*K length IFFT with symbols overlapped with a postponement of N/2, where N is the quantity of subcarriers. This structure decision makes it simple to investigate FBMC and compare with other modulation strategies.
To accomplish full capacity, offset quadrature amplitude modulation (OQAM) preparing is utilized. The genuine and fanciful pieces of a complex information symbol are not transmitted at the same time,
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as the imaginary part is delayed by half the symbol duration.
Fig.4: Block Diagram of FBMC Transmitter The example implements a basic
FBMC demodulator and measures the BER for the chosen configuration in the absence of a channel. The processing includes matched filtering followed by OQAM separation to form the received data symbols. These are
de-mapped to bits and the resultant bit error rate is determined. In the presence of a channel, linear multi-tap equalizers may be used to mitigate the effects of frequency-selective fading.
Fig.5: Block Diagram of FBMC Receiver 2. UFMC V/S OFDM
OFDM, as a multi-carrier modulation technique, has been broadly received by 4G communicationnetworks, for example, LTE and Wi-Fi. It has numerous focal points: heartiness to channel delays, single-tap frequency domain equalization, and productive execution. What is regularly not featured are its costs, for example, the misfortune in otherworldly effectiveness because of higher side-lobes and the exacting synchronization necessities. New modulation
strategies are, in this manner, being considered for 5G communication systems to beat a portion of these components.
For instance, a LTE framework at 20 MHz channel bandwidth capacity utilizes 100 resource blocks of 12 subcarriers each, at an individual subcarrier dividing of 15 kHz. This uses just 18 MHz of the dispensed range, prompting a 10 percent misfortune. Also, the cyclic prefix of 144 or 160 examples for every OFDM symbol prompts another 7 percent spectral efficiency, for a general 17 percent
6 misfortune in conceivable otherworldly effectiveness. With the now characterized ITU prerequisites for 5G networks, applications require higher information rates, lower latency and increasingly proficient range use. This model spotlights on the new tweak system known as Universal Filtered Multi-Carrier (UFMC) and contrasts it and OFDM inside a nonexclusive structure.
3. FBMC V/S OFDM
This paper compares Filter Bank Multi-Carrier (FBMC) with Orthogonal Frequency Division Multiplexing (OFDM) and highlights the merits of the candidate modulation scheme for Fifth Generation (5G) communication systems. This paper compares Filter Bank Multi- Carrier (FBMC) modulation with generic OFDM modulation.The power spectral density of the FBMC transmit signal highlights the low out-of-band leakage.FBMC has lower side lobes, this allows a higher utilization of the allocated spectrum, leading to increased spectral efficiency. FBMC offers ways to overcome the known limitations of OFDM of reduced spectral efficiency and strict synchronization requirements.
These advantages have led it to being considered as one of the
modulation techniques for 5G communication systems.
4. CONCLUSION
FBMC is considered advantageous in comparison to OFDM by offering higher spectral efficiency. Due to the per subcarrier filtering, it incurs a larger filter delay (in comparison to UFMC) and also requires OQAM processing, which requires modifications for MIMO processing.
UFMC is considered advantageous in comparison to OFDM by offering higher spectral efficiency. Sub- band filtering has the benefit of reducing the guards between sub- bands and also reducing the filter length, which makes this scheme attractive for short bursts. The latter property also makes it attractive in comparison to FBMC, which suffers from much longer filter length.
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