| 摘要: | 本論文內容主要探討三個密切相關之主題：對展頻通訊系統之同時多重干擾器/截收器評估、有效之跟隨式干擾機率模型研究，及其於感知無線電通訊之調適運用等。然於步入主題之前，將先進行與本論文研究相關之內容探討，如研究動機、目的、先前相關論文及工作回溯，以及許多與本論文論述相關之基本技術背景基礎，如TRANSEC傳輸安全性概念、展頻技術基礎、傳輸效應模型、天線場型模型，及供分析模擬之想定等；此外，有關DS直接序列及FH跳頻信號之干擾反制及其之涵蓋、偵測、截收，及探究反制等亦進行探討之。三項研究主題敘述如下: 第一個主題係經由可用之方法及衡量指標，提供同時之單一及多重之干擾器/截收器之AJ抗干擾及LPD/I/E低偵測/截收/探究率之評估。吾人發展出一系統化方法，藉由歸整許多與系統相關或幾何位置相關之參數，用以評估一俱同時AJ抗干擾及LPD/I/E低偵測/截收/探究率能力之安全通訊系統性能。吾人基於所提之運用想定，並特針對一典型FHMA跳頻多工及BFSK二元頻率位移鍵入調變方式，探討對於單一及多重之同時干擾器/截收器之安全性之評估及擇優。第二研究主題係以兩種不同之幾何觀察模型及平均式及循序式之兩種掃描方法，分析此有趣之跟隨式干擾模型，用以發展評估此種跟隨式干擾之有效跟隨機率。針對一俱及時掃描(偵測)及傳輸(干擾)之跟隨式干擾進行研究，藉由估算此有效干擾(追隨)機率(h)數值，以驗證其傳輸安全性之FH跳頻展頻性能。第三項主題係有關以”合作式”之CRU感知單元取代先前所提之共位置干擾器/截收器之CR感知無線電調適運用，其係一經由CPR感知機率比以評估即時通訊資源之有效及嶄新模型。基本之DF測向及EL定位技術亦可整合進入吾人所提之感知無線電單元模型，以提供更精確之傳輸延遲預估及時間估算。所提之CRU模型及CPR感知比等對感知無線電網路而言係創新之研究貢獻。 In this thesis, we emphasize on three main topics of concurrent multiple jammer/interceptors evaluations for spread spectrum communication systems, investigations of effective FOJ probability model, and its adaptation to cognitive radio communications, which seem to be different but, in fact, closely related. Before stepping into these main topics, the research motivation, purpose, and previous work survey will be stated first, then some fundamental backgrounds for this thesis, e.g., TRANSEC concept, spread spectrum fundamentals, basic propagation effects model, antenna patterns model, adopted scenarios for analysis and simulations, and etc. will be followed. Hereafter, two countermeasures issues will be examined, which include the countermeasures to jam both DS and FH communication signals and the countermeasures to cover, detect, intercept, or even exploit both DS and FH signals. The three main topics are stated as follows. The first main topic is the AJ and LPD/I/E evaluations for concurrent single and multiple jammer/interceptors via schemes and metrics available. We develop a systematic method for evaluation of a secure communication system with simultaneous AJ and LPD/I/E capabilities by coordinating with many system-dependent and geometric-dependent parameters. For a typical communications system with FHMA and BFSK modulation, single and multiple concurrent jammer/interceptors are examined based on the proposed operation scenarios for security evaluations and trade-offs. The second main topic is the analysis of an interesting FOJ model with two different geometric observation models with elliptic and hyperbolic contours, respectively, and both uniform and sequential scanning schemes, to develop an approach for evaluating the FOJ effective probability. A FOJ model with both real-time scanning (detection) and transmission (jamming) capabilities is examined to verify the FH spread spectrum performance of transmission security by estimating effective jamming probability (h). The last main topic is the adaptation to cognitive radio communication by replacing the collocated jammers/interceptors with “cooperative” cognitive radio units (CRUs), which would be an effective and novel model for evaluating the real time communication resources through cognitive probability ratio (CPR). Fundamental direction finding (DF) and emitter location (EL) techniques are incorporated with proposed cognitive radio unit (CRU) and models for more accurate propagation delay prediction and estimation. The proposed CRU model and CPR is innovative for cognitive radio network evaluations. |
