高頻（High Frequency， HF）通訊因具備長距離傳播與無需依賴地面基礎設施之特性，在軍事通訊、緊急通訊及偏遠地區通訊中具有重要應用價值。其中，近垂直入射（Near Vertical Incidence Skywave， NVIS）傳播模式可提供中短距離之區域性穩定覆蓋，有效填補直射波與低仰角天波之間的通訊盲區。而HF NVIS 通道具有高度時間變動性，並易受到多徑效應、都卜勒頻移及外部干擾影響，導致通訊品質不太穩定。 為提升 HF NVIS 系統之抗干擾能力，本研究提出一套結合自適應頻率跳頻（Adaptive Frequency Hopping， Adaptive FH）與到達方向估測（Direction of Arrival， DOA）及波束成形（Beamforming）之聯合抗干擾架構。於頻率域方面，Adaptive FH 透過通道感知與通道評分機制，動態選擇高品質頻道進行傳輸，有效避免受干擾頻道；於空間域方面，DOA 與波束成形技術可估測訊號入射方向並抑制干擾方向之訊號，進一步提升接收訊號品質。 本研究建立一套 HF NVIS 通道模擬環境，考慮多徑傳播、都卜勒效應、通道衰落及動態干擾等因素，並比較 No FH、Conventional FH 與 Adaptive FH（結合 DOA）三種機制之效能。模擬結果顯示，Adaptive FH + DOA 在各訊雜比（SNR）條件下均能有效降低位元錯誤率（Bit Error Rate， BER）與中斷機率（outage probability），並顯著提升系統可靠度（reliability）。此外，該聯合架構在動態干擾環境中展現出良好之穩定性與適應能力，顯示其具備實際應用潛力。 本研究證實結合頻率域與空間域之聯合抗干擾機制，可有效提升 HF NVIS 通訊系統之整體效能與穩定性，並為未來高可靠度無線通訊系統提供可行之設計方向。;High Frequency (HF) communication plays a crucial role in long-range and infrastructure-independent communication scenarios， such as military operations， emergency communications， and remote area connectivity. Among various HF propagation modes， Near Vertical Incidence Skywave (NVIS) propagation provides reliable regional coverage for medium- and short-range communication， effectively bridging the coverage gap between ground wave and low-elevation skywave propagation. However， HF NVIS channels are highly time-varying and are severely affected by multipath fading， Doppler shifts， and external interference， leading to performance degradation. To enhance the anti-jamming capability of HF NVIS systems， this study proposes a joint anti-interference framework that integrates Adaptive Frequency Hopping (Adaptive FH) with Direction of Arrival (DOA) estimation and beamforming techniques. In the frequency domain， Adaptive FH dynamically selects high-quality channels based on real-time channel sensing and scoring mechanisms， thereby avoiding heavily interfered channels. In the spatial domain， DOA estimation combined with beamforming enables directional signal enhancement and interference suppression， improving the received signal quality. A comprehensive HF NVIS channel simulation environment is developed in this work， incorporating multipath propagation， Doppler effects， channel fading， and dynamic jamming scenarios. The performance of three schemes—No FH， Conventional FH， and Adaptive FH with DOA—is evaluated and compared. Simulation results demonstrate that the proposed Adaptive FH + DOA approach significantly reduces the Bit Error Rate (BER) and outage probability while improving system reliability across all Signal-to-Noise Ratio (SNR) conditions. Furthermore， the joint approach exhibits superior stability and adaptability under dynamic interference environments. In conclusion， the integration of frequency-domain and spatial-domain anti-jamming techniques effectively enhances the overall performance and robustness of HF NVIS communication systems， providing a promising solution for future reliable wireless communication systems.
