scholarly journals On the Practical Implementation of VFDM-based Opportunistic Systems: Issues and Challenges

2012 ◽  
Vol 2 (1-2) ◽  
Author(s):  
Marco Maso ◽  
Leonardo S. Cardoso ◽  
Ejder Bastug ◽  
Nguyen Linh-Trung ◽  
Mérouane Debbah ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Null Space ◽  
Delay Spread ◽  
Practical Implementation ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Test Bed ◽  
Short Root ◽  
The Impact ◽  
Secondary Link

Vandermonde-subspace frequency division multiplexing (VFDM) is a physical layer technique for cognitive two-tiered networks, allowing for the coexistence of an orthogonal frequency division multiplexing (OFDM) legacy system and a cognitive secondary system in a time division duplex mode. It consists of a linear null-space precoder used by the secondary transmitter to effectively cancel the interference towards one or more primary receivers, while guaranteeing a non-negligible rate to a served secondary receiver. In this work, we propose an implementation of an experimental test-bed using the new SDR4All platform developed at the Alcatel-Lucent Chair on Flexible Radio (SUPELEC) to take a step towards a proof of concept of a VFDM-based system. We focus on the secondary link, where an opportunistic transmitter/receiver pair communicates over moderately frequency selective channels, characterized by very short root mean square (r.m.s.) delay spreads and non uniform power delay profiles (PDP). The obtained results show the practical feasibility of a VFDM transmission over a secondary link. However, a significant bit error rate (BER) loss with respect to the previously shown achievable theoretical performance is evident. A thorough analysis of the structure of the VFDM precoder is carried out and the impact of the channel characteristics on the performance of the opportunistic system is discussed. Numerical findings demonstrate that the potential BER drop can be addressed by designing a suitable flexible receiver able to deal with the effect induced by non uniform PDP and short r.m.s. delay spread channels.

scholarly journals Advantages of Spectrally Efficient Frequency Division Multiplexing Over Orthogonal Frequency Division Multiplexing

2020 ◽  
Vol 9 (8) ◽  
pp. 238-244
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Sphere Decoder ◽  
Symbol Rate ◽  
Transmission Length ◽  
Spectrally Efficient ◽  
The Impact

An analysis on Spectrally Efficient Frequency Division Multiplexing (SEFDM) is contrast with Orthogonal Frequency Division Multiplexing (OFDM) considering the impact on Peak to Average Power Ratio (PAPR) and nonlinearities within fibre. With respect to OFDM the sub-carriers in SEFDM signals are compressed adjacent to each other at a rate of frequency lesser than the symbol rate. At the receiver end we have utilized the Sphere Decoder which is used to recover the data to remunerate the Interference created by the compressed signals (ICI) faced in the system. This research shows the advantages by using SEFDM and evaluates its achievement. PAPR. when compared with OFDM, while effects of non-linear fibres are considered. The use of various formats of modulation going from 4-QAM to 32-QAM, shows that the SEFDM signals have a noteworthy increment in the transmission length with respect to ordinary signals.

scholarly journals 5G F-OFDM Waveform Based Software-Defined Radio Technology

2021 ◽  
Vol 20 ◽  
pp. 68-80
Author(s):  
Dia Mohamad Ali ◽  
Zhraa Zuheir Yahya
Keyword(s):  
Software Defined Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Hardware Implementation ◽  
Software Radio ◽  
Spectrum Efficiency ◽  
Practical Implementation ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Fifth Generation ◽  
Radio Technology

Filtered-orthogonal frequency division multiplexing (F-OFDM) is a quasi-orthogonal waveform candidate for the applications of the fifth generation (5G) communication system. In this study, an F-OFDM waveform with unequal sub-band sizes is proposed to improve the spectrum efficiency (SE) of the 5G system. The proposed waveform is modeled with the Blackman window-sinc filter and is developed based on the software-defined radio (SDR) technology for practical implementation. The result shows that the F-OFDM performance of the simulation and hardware implementation is approximately the same. The SE using the proposed F-OFDM waveform is 6% and 5.8% higher than the SE using the conventional OFDM waveform under the simulation in the LabVIEW NXG simulator and under the practical use in the universal software radio peripheral (USRP) platform, respectively.

scholarly journals Femtocell Number Influence to SINR and Throughput on Coexistence GSM and LTE Network

2020 ◽  
Vol 17 (2) ◽  
pp. 145
Author(s):  
Muhammad Yaser
Keyword(s):  
Radio Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Network Performance ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Throughput Performance ◽  
Lte Network ◽  
Femtocell Network ◽  
Gsm Network ◽  
The Impact

<p><em>Coexistence GSM network and LTE femto relies on the number of femtocell deployment position. In the earlier study, the impact of macrocell size, femtocell deployment position, and coexistence LTE femtocell network integrated with GSM macrocell had been discussed. LTE femtocell used Orthogonal Frequency Division Multiplexing (OFDM) technology for its operation. In coexistence networks, LTE femtocells operate with OFDM technology so that they can utilize several radio frequency fractions without disturbing other parts of the frequency located between them. Unfortunately, the impact of femtocell number on the coexistence network had not been discussed. SINR and femtocell throughput performance are mathematically analyzed. The result showed that femtocell number had an effect on the coexistence network performance. SINR GSM, SINR femtocell and femtocell throughput significantly degraded as the femtocell number increased. The increasing femtocell number from M =0 to M =20 on each GSM cell cause around 14 dB degradation in SINR GSM, 3 dB decline in SINR Femto, approximately 1.7% decline in throughput for K = 4. Meanwhile for K = 7, the increasing femtocell number cause 17 dB decline in SINR GSM 6,5 dB decline in SINR Femto and 3.2 % decline in throughput. Those happened since the LTE femtocell interference went up. So femtocell number greatly influences the Coexistence GSM Network and LTE femtocell.</em></p><p><em><br /></em></p><p><em>Jaringan koeksistensi GSM dan LTE Femto sangat tergantung pada kondisi sebaran femtocell, di</em><em> </em><em>antaranya jumlah femtocell. Pada studi sebelumnya telah dibahas mengenai pengaruh ukuran macrocell dan posisi penyebaran femtocell dan jaringan koeksistensi LTE femtocell yang diintegrasikan dengan GSM macrocell. Dalam jaringan koeksistensi, LTE femtocell beroperasi dengan teknologi Orthogonal Frequency Division Multiplexing (OFDM) sehingga dapat memanfaatkan beberapa fraksi frekuensi radio tanpa mengganggu bagian lain dari frekuensi yang terletak di antaranya Namun studi sebelumnya belum membahas pengaruh jumlah femtocell pada jaringan koeksistensi ini. Kinerja kedua sistem yang dalam hal ini SINR dan femtocell throughput dianalisis secara matematis. Hasil simulasi menunjukan bahwa jumlah femtocell memiliki efek pada kinerja jaringan koeksistensi. SINR GSM, SINR femtocell dan femtocell throughput semakin menurun seiring dengan peningkatan jumlah femtocell</em><em>.</em><em> Peningkatan jumlah femtocell dari M = 0 ke M = 20 pada setiap sel GSM menyebabkan penurunan sekitar 14</em><em> </em><em>dB SINR GSM, penurunan 3</em><em> </em><em>dB SINR Femto, sekitar1, 7% penurunan throughput untuk K = 4. Sementara itu untuk K = 7, peningkatan junlah femtocell menyebabkan penurunan 17</em><em> </em><em>dB SINR GSM, penurunan 6.5</em><em> </em><em>dB SINR Femtocell dan penurunan 3, 2% dalam throughput. Hal ini disebabkan oleh peningkatan interferensi dari LTE femtocell. Maka jumlah LTE femtocell sangat mempengaruhi sistem koeksistensi LTE femtocell dengan jaringan GSM</em><em>.</em><em></em></p><p><em><br /></em></p>

scholarly journals KINERJA SISTEM COFDM (CODED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING) PADA KANAL RADIO MOBILE

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
Hendra Winata ◽  
Heroe Wijanto ◽  
Suyatno Suyatno
Keyword(s):  
Wireless Lan ◽  
Orthogonal Frequency Division Multiplexing ◽  
Delay Spread ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Coding Gain ◽  
Video Broadcasting ◽  
Forward Error ◽  
Inter Symbol Interference

Komunikasi data berkecepatan tinggi memerlukan teknik modulasi yang dapat mengatasi terjadinya ISI (Inter-Symbol Interference) dan respons frekuensi kanal yang tidak rata. OFDM (Orthogonal Frequency Division Multiplexing) merupakan teknik transmisi multicarrier dengan periode simbol relatif lebih lebar dibandingkan nilai delay spread kanal. Dengan subcarrier spektral yang lebih sempit dari lebar-pita frekuensi koheren, OFDM diharapkan memiliki ketahanan terhadap gangguan kanal yang tidak rata. FEC (Forward Error Correcting) masih dibutuhkan untuk meminimumkan efek kesalahan akibat dari beberapa subcarrier yang mengalami fading lebih kuat dibandingkan lainnya. FEC dengan teknik pengkodean konvolusional dan interleaver banyak dipakai pada standar OFDM seperti Wireless LAN 802.11a dan Direct Video Broadcasting. Hasil simulasi menunjukkan pengkodean konvolusional [133 171] memberikan nilai coding gain maksimal 6 dB untuk modulasi subcarrier QPSK dan 7 dB untuk 16-QAM. Pada kanal radio mobile dengan frekuensi doppler 0, 9, 56 dan 130 Hz, diperoleh coding gain 7 dB. Penggunaan matriks interleaver 32?18 (IS�95) bekerja kurang optimal dengan perbaikan daya kurang dari 1dB. Ketika frekuensi doppler 130 Hz, matriks interleaver 100?96 mampu memperbaiki kinerja sistem secara siginifikan, BER di sekitar 10-6 dicapai pada SNR = 16 dB.Kata kunci: OFDM, interleaver, delay spread, frekuensi doppler, coding gain, IFFT-FFT

Performance investigation of free space optics link employing polarization division multiplexing and coherent detection-orthogonal frequency division multiplexing under different link parameters

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Tanu Shri ◽  
Anita Suman ◽  
Parveen Kumar
Keyword(s):  
Free Space ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Capacity ◽  
Coherent Detection ◽  
Free Space Optics ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Test Bed ◽  
Space Optics ◽  
Polarization Division Multiplexing

AbstractFree space optics (FSO) is a novel transmission technique capable of providing high-capacity links with large bandwidth and robustness against electromagnetic waves interference. In this work, we demonstrate the development of a 100 Gbps FSO link which employs the hybridization of polarization division multiplexing technique and coherent detection-orthogonal frequency division multiplexing technique. Further, we have investigated the system performance by varying different parameters like the input power, the size of the receiver antenna, wavelength of laser beam, the angle of beam divergence, and the additional losses. The proposed system has been modeled and analyzed over Optisystem test bed.

scholarly journals Hardware Implementation of MISO on Orthogonal Frequency Division Multiplexing Platform with the Help of Alamouti Algorithm

2017 ◽  
Vol 63 (2) ◽  
pp. 137-143
Author(s):  
Seetaiah Kilaru
Keyword(s):  
Field Programmable Gate Array ◽  
Orthogonal Frequency Division Multiplexing ◽  
Hardware Implementation ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Test Bed ◽  
System Generator ◽  
Field Programmable ◽  
Simulation Results ◽  
Half Decade

Abstract Many software based OFDM techniques were proposed from last half decade to improve the performance of the system. This paper tried to implement the same with Hardware implementation. We created Hardware based MISO platform with OFDM. We implemented Alamouti algorithm on this test bed. The test bed is implemented with the help of Field Programmable Gate Array (FPGA). The test bed is functionalized with the help of FPGA through Xilinx based system generator for DSP. In this paper we considered the 2×1 MISO implementation with Alamouti algorithm. The simulation results showed that BER and SNR are considerably high for MISO than SISO. The results also proved that proposed OFDM based Alamouti implementation for MISO is excellent in all performance criterions.

Performance analysis of GFDM in various fading channels

2016 ◽  
Vol 35 (1) ◽  
pp. 225-244 ◽  
Author(s):  
Shravan Kumar Bandari ◽  
V.V. Mani ◽  
A. Drosopoulos
Keyword(s):  
Fading Channels ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cellular Systems ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Test Bed ◽  
Ultra Low Power ◽  
Content Type ◽  
Analytical Expressions

Purpose – The purpose of this paper is to study the performance of generalized frequency division multiplexing (GFDM) in some frequency selective fading channels. The exact symbol error rate (SER) expressions in Hoyt (Nakagami-q) and Weibull-v fading channels are derived. A GFDM transceiver simulation test bed is provided to validate the obtained analytical expressions. Design/methodology/approach – Modern cellular system demands higher data rates, very low-latency transmissions and sensors with ultra low-power consumption. Current cellular systems of the fourth generation (4G) are not able to meet these emerging demands of future mobile communication systems. To address this requirement, GFDM, a novel multi-carrier modulation technique is proposed to satisfy the future needs of fifth generation technology. GFDM is a block-based transmission method where pulse shaping is applied circularly to individual subcarriers. Unlike traditional orthogonal frequency division multiplexing, GFDM transmits multiple symbols per subcarrier. The authors have used the probability density function approach in solving the final analytical expressions. Findings – Detailed analysis of GFDM performance under Hoyt-q, Weibull-v and Log-Normal Shadowing fading channels. Exact analytical formulae were derived which support the simulations carried out by authors and other authors. The exact dependence of SER on fading parameters and roll-off factor α in the raised cosine pulse shape filter was determined. Practical implications – Development and fabrication of high-performance GFDM systems under fading channel conditions. Originality/value – Theoretical support to simulated system performance.

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