Umaisaroh, Umaisaroh (2019) Capacity Improvement In HF Skywave Communications. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Sistem komunikasi yang terjangkau yang dapat diterapkan pada jarak jauh merupakan hal yang menantang bagi para peneliti. Sistem komunikasi High Frequency (HF) yang menempati frekuensi 3-30 MHz yang ditransmisikan melalui oleh lapisan ionosfer, dapat mencapai transmisi sinyal jarak jauh. Kemampuan ini telah membuat keuntungan untuk menyediakan layanan jarak jauh, khususnya bencana darurat, perawatan kesehatan, dan pendidikan. Namun, bandwidth saluran sistem komunikasi radio HF terbatas pada 3-20 kHz. Oleh karena itu, diperlukan lebih banyak kecerdikan untuk mencapai kapasitas saluran yang memadai,karena saluran radio ionosfer juga mengalami pemudaran multipath dan dispersi waktu dan frekuensi. Untuk mengatasi keterbatasan ini, sebagai kontribusi kami, kami berupaya meningkatkan kapasitas saluran dan memungkinkan komunikasi multi-pengguna dengan gangguan rendah dalam komunikasi radio digital HF. Penelitian ini melaporkan hasil inevestigasi mengenai karakteristik saluran HF 2 × 2 multiple-input multiple-output (MIMO) skywave terpolarisasi dengan menggunakan cross-dipole (sepasang dipol berorientasi horizontal yang terpolarisasi ortogonal) digunakan pada kedua ujungnya untuk mencapai saluran peningkatan kapasitas. Peran gelombang Ordinary (O) dan Extraordinary (X) yang terpolarisasi sirkuler secara inheren hadir dalam saluran, dengan jangkauan pemancar-penerima yang cukup dekat untuk memungkinkan perambatan hop tunggal tetapi juga cukup jauh untuk membuat lintasan miring. Artikel ini berupaya untuk menurunkan matriks saluran MIMO 2 × 2 yang dapat digunakan untuk memeriksa properti polarisasi silang dan Capacity Improvement Factor (CIF). Hasil menunjukkan bahwa karena adanya mode O dan X, kontribusi daya gelombang dari dua pemancar yang tiba di masing-masing penerima adalah sama. Evaluasi telah diamati untuk saluran MIMO dengan NVIS dan saluran miring melalui simulasi dan pengukuran ray-tracing. Dengan cara lain, untuk memungkinkan komunikasi multi-pengguna, efek dekat antara pengguna terjadi jika daya pancar identik digunakan untuk masing-masing pengguna tetapi terletak di lokasi yang berbeda dan jarak antara masing-masing pemancar dan hub. Dalam studi ini, mekanisme kontrol daya diusulkan untuk mengkompensasi daya pancar karena propagasi jarak.
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Affordable communication systems which are required in long distance area are a challenge for researchers. High frequency (HF) communication system occupying 3-30 MHz when propagated through the ionosphere, can achieve long distance signal transmission. These capabilities have made advantages to provide long-distance services, particularly emergency disaster, health care, and education. However, the channel bandwidth of HF radio communication systems is limited to 3-20 kHz typically. Therefore more ingenuity is required to achieve sufficiently channel capacity, the more as the ionospheric radio channel suffers from multipath fading and time and frequency dispersion. To overcome this limitation, as our contribution, we attempt to increase the channel capacity and to allow multi-user communications with low interference in HF digital radio communications. This research reports the investigation into characteristics of Hf skywave polarized 2×2 multiple-input multiple-output (MIMO) channels by employing cross-dipoles (a pair of orthogonally-polarized horizontally-oriented dipoles) are used at both ends to achieve the channel capacity improvement. It considers the role of orthogonal circularly-polarized Ordinary (O) and Extraordinary (X) waves inherently present in the channel, with the transmitter-receiver range being near enough to allow single-hop propagation but also distant enough to make the trajectory oblique. This article attempts to derive the 2×2 MIMO channel matrix that can be used to examine the cross-polarization property and the capacity improvement factor (CIF). The results suggest that due to the presence of the O and X modes, the power contribution of the waves from the two transmitters that arrive at each receiver is equal. The evaluation has been observed for MIMO channels with NVIS and oblique channels through ray-tracing simulation and measurement. In another way, to allow multi-user communications, the near-effect between users occurs if the identical transmit power used for each user but located in the different location and the range between each transmitter and relay. In this study, the power control mechanism is proposed to compensate for distance propagation loss.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | HF, ionosphere, MIMO, capacity, multi-user |
| Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5103.2 Wireless communication systems. Two way wireless communication T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101 Telecommunication |
| Divisions: | Faculty of Electrical Technology > Electrical Engineering > 20001-(S3) PhD Thesis |
| Depositing User: | Miss Umaisaroh Umaisaroh |
| Date Deposited: | 23 Jul 2026 06:39 |
| Last Modified: | 23 Jul 2026 06:39 |
| URI: | http://repository.its.ac.id/id/eprint/70461 |
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