Usage of different modulation applications in OFDM systems and performance comparison

Öz

OFDM (orthogonal frequency division multiplexing) systems are the most efficient use of today's radio frequency spectrum. The system is the simultaneous splitting of a signal into small signals and sending them to the receiver. It is mainly a need in high-capacity data transfer and multi-user systems. Depending on the usage purpose, the OFDM method provides a data transmission with maximum accuracy at the highest speed as long as an appropriate and high-performance modulation type is used. This study performed an FDM communication simulation primarily for multiple data transmissions over a single line. After selecting the carrier frequencies used in FDM, the necessity of the OFDM communication method is proved when considering the high quality of the communication. In the next phase, performance comparisons were made by calculating the BER (Bit error rate) value at different SNR (signal to noise ratio) and multipath fading values of the modulations used in the OFDM method. Specific variable values that the modulation type providing the highest accuracy data transmission has been determined in this study. As a result of the comparison, the best BER value at 8-way communication and 0 SNR was found at 0.28 in the BPSK modulation type. In 8-way transmission and 30 SNR measurements, the lowest BER value was 0.016. In all comparisons made among the used modulation types 'BPSK, QPSK, 8PSK, 16QAM, 32QAM, 64QAM', the lowest BER values were determined in the BPSK modulation type.

Anahtar Kelimeler

• OFDM
• Digital Communication
• BER

OFDM sistemlerinde farklı modülasyon uygulamalarının kullanımı ve performans karşılaştırması

Öz

Öz: OFDM (ortogonal frekans bölmeli çoğullama) sistemleri günümüz radyo frekans spektrumunun en verimli kullanımıdır. Sistem, bir sinyalin eş zamanlı olarak küçük sinyallere bölünerek alıcıya gönderilmesidir. Özellikle yüksek kapasiteli veri iletimi ve çok kullanıcılı sistemlerde ihtiyaç duyulmaktadır. OFDM yöntemi, kullanım amacına bağlı olarak, uygun ve yüksek performanslı bir modülasyon tipi kullanıldığı takdirde en yüksek hızda maksimum doğrulukla veri iletimi sağlamaktadır. Bu çalışmada, öncelikle tek bir hat üzerinden çoklu veri iletimi için bir FDM haberleşme simülasyonu gerçekleştirilmiştir. FDM'de kullanılan taşıyıcı frekansları seçildikten sonra, haberleşmenin yüksek kalitesi de göz önüne alındığında OFDM haberleşme yönteminin gerekliliği kanıtlanmıştır. Bir sonraki aşamada, OFDM yönteminde kullanılan modülasyonların farklı SNR (sinyal gürültü oranı) ve çok yollu sönümlenme değerlerinde BER (Bit hata oranı) değeri hesaplanarak performans karşılaştırmaları yapılmıştır. Bu çalışmada, en yüksek doğrulukta veri iletimini sağlayan modülasyon tipinin belirli değişken değerleri belirlenmiştir. Karşılaştırma sonucunda 8 yollu haberleşme ve 0 SNR'da en iyi BER değeri 0,28 olarak BPSK modülasyon tipinde bulunmuştur. 8 yollu iletim ve 30 SNR ölçümünde ise en düşük BER değeri 0,016 olmuştur. Kullanılan modülasyon tipleri 'BPSK, QPSK, 8PSK, 16QAM, 32QAM, 64QAM' arasında yapılan tüm karşılaştırmalarda en düşük BER değerleri BPSK modülasyon tipinde belirlenmiştir.

Anahtar Kelimeler

• OFDM
• Sayısal Modülasyon
• BER

Kaynakça

1. S. Kumar and Payal, Enhancing Performance of Coherent Optical OFDM FSO Communication Link Using Cascaded EDFA, Wirel. Pers. Commun., no. 0123456789, 2021, DOI: 10.1007/s11277-021-08506-z.
2. J. Zhou et al., 256-QAM Interleaved Single Carrier FDM for Short-Reach Optical Interconnects, IEEE Photonics Technol. Lett., vol. 29, no. 21, pp. 1796–1799, 2017, DOI: 10.1109/LPT.2017.2752215.
3. K. Elango and K. Muniandi, VLSI implementation of an area and energy-efficient FFT/IFFT core for MIMO-OFDM applications, Ann. des Telecommun. Telecommun., vol. 75, no. 5–6, pp. 215–227, 2020, DOI: 10.1007/s12243-019-00742-6.
4. K. A. Balaji and K. Prabu, BER analysis of relay assisted PSK with OFDM ROFSO system over Malaga distribution including pointing errors under various weather conditions, Opt. Commun., vol. 426, no. May, pp. 187–193, 2018, DOI: 10.1016/j.optcom.2018.05.027.
5. R. Hema, S. Sudha, and K. Aarthi, Performance studies of MIMO based DCO-OFDM in underwater wireless optical communication systems, Journal of Marine Science and Technology (Japan), vol. 26, no. 1. pp. 97–107, 2021, DOI: 10.1007/s00773-020-00724-7.
6. W. S. Jung, K. W. Lim, and Y. B. Ko, Utilising partially overlapped channels for OFDM-based 802.11 WLANs, Comput. Commun., vol. 63, no. 1, pp. 77–86, 2015, DOI: 10.1016/j.comcom.2015.02.013.
7. C. Baquero Barneto et al., Full-Duplex OFDM Radar with LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements, IEEE Trans. Microw. Theory Tech., vol. 67, no. 10, pp. 4042–4054, 2019, DOI: 10.1109/TMTT.2019.2930510.
8. H. Paz Penagos, OFDM comparison with FFT and DWT processing for DVB-T2 wireless channels, Inge Cuc, vol. 14, no. 2, pp. 97–105, 2018, DOI: 10.17981/ingecuc.14.2.2018.09.

9. A. Al-Dweik and F. Xiong, Frequency-hopped multiple-access communications with noncoherent M-ary OFDM-ASK, IEEE Trans. Commun., vol. 51, no. 1, pp. 33–36, 2003, DOI: 10.1109/TCOMM.2002.807620.
10. J. Marti and J. Capmany, Laser Linewidth Impairment on Thean Performance of OFDM-FSK Systems Employing Single-Cavity Fabry-Perot Demultiplexers, IEEE Photonics Technol. Lett., vol. 7, no. 5, pp. 561–563, 1995, DOI: 10.1109/68.384544.
11. H. Huh, F. Lu, and J. V. Krogmeier, Exact intersymbol interference analysis for upsampled OFDM signals with symbol timing errors, IEICE Trans. Commun., vol. E100B, no. 8, pp. 1472–1479, 2017, DOI: 10.1587/transcom.2016EBP3433.
12. S. Ertürk, Sayısal Haberlesme, Birsen Yayınevi 2005.
13. S. Sharma and R. Gupta, Performance Comparison of OFDM System with Different Modulation Methods, Commun. Appl. Electron., vol. 5, no. 2, pp. 18–21, 2016, DOI: 10.5120/cae2016652222.
14. S. Thai Le et al., comparison of bit error rate estimation methods for QPSK CO-OFDM transmission, IEEE Photonics Technol. Lett., vol. 26, no. 22, pp. 2244–2247, 2014, DOI: 10.1109/LPT.2014.2352460.
15. J. Hoxha, S. Shimizu, and G. Cincotti, On the performance of all-optical OFDM based PM-QPSK and PM-16QAM, Telecommun. Syst., vol. 75, no. 4, pp. 355–367, 2020, DOI: 10.1007/s11235-020-00687-5.
16. B. Peng, X. Wang, and S. Ten Brink, On Receive Window Design for UF-OFDM Signals over Multipath Channels, IEEE Commun. Lett., vol. 24, no. 10, pp. 2349–2352, 2020, DOI: 10.1109/LCOMM.2020.3005996.
17. Shoayb Mohammed, Orthogonal Frequency Division Multiplexing (OFDM). https://www.slideshare.net/shoaybmohammed/orthogonal-frequency-division-multiplexing-ofdm-69596792 (accessed May 16, 2021).
18. S. Kamal, H. Kang, C. A. Azurdia Meza, and D. S. Kim, Improved dual sync pulses to reduce ICI power and PAPR in OFDM-based systems, KSII Trans. Internet Inf. Syst., vol. 14, no. 12, pp. 4930–4948, 2020, doi: 10.3837/tiis.2020.12.017.
19. J. Street, ofdm_sim, 2015. https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/67156/versions/1/previews/OFDM_Channel_Estimation/html/ofdm_sim.html (accessed Apr. 26, 2021).
20. A. G. Bolaji and T. Shongwe, Performance comparison of modified BPSK-OFDM and QFSK-OFDM in PLC channel noise, Int. J. Electron. Telecommun., vol. 66, no. 4, pp. 499–605, 2020, doi: 10.24425-ijet.2020.134017/740.
21. A. H. A. Kareem, Performance evaluation of PSK all optical OFDM system based on arrayed waveguide grating under different weather conditions, Int. J. Microw. Opt. Technol., vol. 15, no. 1, pp. 85–94, 2020.
22. C. Xiang, X. Yang, X. Zhou, X. Zhu, J. Xu, and Q. He, Improved Training Sequence Channel Estimation Scheme in 16QAM MB-OFDM UWBoF System, Adv. Condens. Matter Phys., vol. 2020, 2020, doi: 10.1155/2020/6273892.
23. M. F. Huang et al., EDFA-only WDM 4200-km transmission of OFDM-16QAM and 32QAM, IEEE Photonics Technol. Lett., vol. 24, no. 17, pp. 1466–1468, 2012, doi: 10.1109/LPT.2012.2205378.
24. Z. Zhou, L. Liu, and G. Wang, 2.03 Gbps visible light communication system with 64-QAM-OFDM utilizing a single flip-chip blue GaN-LED, J. Mod. Opt., vol. 66, no. 21, pp. 2114–2118, 2019, doi: 10.1080/09500340.2019.1695974.
25. Louis E. Frenzel Jr., Principles of Electronic Communication Systems, vol. 28, no. 10. 2015