【摘要】：認知無線網(wǎng)絡（Cognitive Radio Network, CRN）允許認知用戶（也稱作次用戶）使用主用戶的頻譜資源。一般來說，認知無線網(wǎng)絡有三種工作模式：重疊模式（UnderlayParadigm），覆蓋模型（Overlay Paradigm）和交織模式（Interweave Paradigm）。當采用重疊模式時，從主用戶（Primary User）的角度來看，允許次用戶（Secondary User）與主用戶同時傳輸數(shù)據(jù)，只要它對主用戶的干擾在主用戶容忍的范圍之內；而從次用戶的角度來看，次用戶必須合理地控制它的發(fā)射功率，在保證不對主用戶產(chǎn)生有害干擾的同時，盡可能得到較高的傳輸速率。因此動態(tài)資源分配（Dynamic ResourceAllocation，DRA）變得至關重要。次用戶利用它所獲得的信道狀態(tài)信息（Channel State Information, CSI）動態(tài)調整發(fā)射功率、傳輸速率、帶寬甚至天線波束等參數(shù)來獲得最好的性能，同時保證主鏈路的服務質量。 近些年隨著無線網(wǎng)絡的飛速發(fā)展及提供的業(yè)務不斷多樣化，例如基于Internet協(xié)議的語言、視頻等無線業(yè)務不斷增加。這些業(yè)務對網(wǎng)絡傳輸時延都非常敏感，需要滿足一定的時延服務質量（Quality of Service, QoS）。因此滿足不同業(yè)務時延QoS需求成為目前無線網(wǎng)絡研究的熱點。尤其是認知無線網(wǎng)絡，由于頻譜共享及干擾功率約束，滿足不同時延QoS需求更具有挑戰(zhàn)性。因此在認知網(wǎng)絡中研究具有時延約束的功率控制策略具有重要意義。 本論文基于有效容量模型，，研究了認知無線網(wǎng)絡基于時延約束的功率控制策略，深入分析了不同衰落環(huán)境下優(yōu)化參數(shù)（有效容量或干擾功率）與時延約束之間的關系。提出了利用分集接收在保證次用戶時延約束的同時提高認知無線系統(tǒng)的容量性能；利用OFDM多子載波傳輸減小次用戶對主用戶產(chǎn)生的干擾。主要研究工作內容如下： (一)首先研究了單天線認知無線系統(tǒng)具有時延QoS約束的最優(yōu)功率控制策略。提出的功率控制策略以最大化認知無線系統(tǒng)有效容量為目標，受限于平均干擾溫度門限。推導出時延約束最嚴格和最寬松兩種極限情況下功率控制表達式，以及最優(yōu)功率控制下Nakagami衰落信道的有效容量閉合解。研究了非對稱衰落信道（包括不同的衰落類型及信道增益）不同時延約束條件下認知無線系統(tǒng)的容量性能。結果表明當時延約束較寬松時，干擾信道（次用戶發(fā)射端與主用戶接收端之間）特性對認知系統(tǒng)容量性能起決定性作用；當時延約束較嚴格時，干擾信道特性對認知無線系統(tǒng)容量性能的影響逐步減小，而認知信道（次用戶發(fā)射端與次用戶接收端之間）特性對認知無線系統(tǒng)容量將起決定性作用。在上述研究的基礎上，將主用戶數(shù)從一個擴展到n個，研究了認知無線系統(tǒng)滿足不同時延QoS需求時系統(tǒng)容量與n之間的關系。結果表明當時延約束較寬松時，有效容量隨n的增加而降低；而當時延約束變得越來越嚴格，這種影響逐漸減小。 其次研究了多天線認知無線系統(tǒng)配置多個分集支路，有效容量與時延約束之間的關系。其中次用戶接收端采用最大比合并（Maximum Ratio Combining, MRC）接收。結果表明增加天線分集支路可以提高認知信道的容量性能。特別是當時延約束較嚴格時，有效容量增益得到顯著提高。因此多天線配置更適合于時延敏感業(yè)務。 (二)首先研究了單載波認知無線系統(tǒng)具有時延QoS約束的最優(yōu)功率控制策略。提出的功率控制策略在保證到達業(yè)務流所需時延QoS約束的同時，最小化主用戶接收端平均干擾功率。推導出Nakagami衰落環(huán)境下平均干擾功率的閉合解。分析了不同衰落條件下時延約束與干擾功率之間的關系。結果表明時延約束與干擾功率之間存在固有的折中。當次用戶的時延約束要求越嚴格，它對主用戶產(chǎn)生的干擾越大。尤其是當認知信道處于深衰落時，干擾功率隨時延約束指數(shù)θ的增大而急劇增加；而當認知信道質量較好時，干擾功率隨時延約束指數(shù)θ的增大而增加的速率明顯放緩。 其次研究了OFDM多載波認知無線系統(tǒng)具有時延QoS約束的最優(yōu)功率分配方案。提出的功率分配方案在保證次用戶時延QoS約束的同時，最小化所分配子信道總的平均干擾功率之和。從頻域角度分析，此功率分配策略按照認知子信道與干擾子信道功率之比從大到小的順序以注水方式分配功率。而從時域角度分析，此策略又依賴于時延QoS約束指數(shù)。分析了不同子信道數(shù)情況下干擾功率與時延約束之間的關系。結果表明當時延約束要求較嚴格時，可以通過增加子信道數(shù)目來降低次用戶對主用戶的干擾。因此在滿足干擾溫度門限的前提下，基于多載波CR的功率分配比基于單載波CR的功率控制允許時延要求更嚴格的次用戶接入主用戶網(wǎng)絡。 (三)研究了非理想信道狀態(tài)信息（Imperfect CSI）認知無線系統(tǒng)有效容量性能。其中次用戶接收端部署MRC分集，利用最小均方誤差準則（Minimum Mean Square Error,MMSE）估計信道誤差。得到了非理想CSI基于平均干擾功率約束的功率控制策略及有效容量表達式。結果表明信道估計誤差導致認知無線系統(tǒng)容量降低，尤其是時延約束較寬松時影響更大。而增加分集支路不僅可以提高容量增益；同時還可以補償信道估計誤差導致的容量損失。 分析了非理想CSI基于干擾中斷約束的有效容量增益。得到了滿足最嚴苛干擾中斷約束條件下的功率控制策略及對應的有效容量下界表達式。分析了有效容量與干擾中斷門限、估計誤差之間的關系。結果表明基于干擾中斷約束與嚴格峰值干擾功率約束相比，即使很小的干擾中斷都可以帶來較大的容量增益。特別是時延約束較寬松時，容量增益更顯著。另外對于非理想CSI，只要允許一定程度的干擾中斷，基于峰值干擾中斷約束與基于平均干擾功率約束所得到的容量性能差別不大。
[Abstract]:A cognitive radio network (CRN) allows a cognitive user, also known as a secondary user, to use the spectrum resources of the primary user. In general, the cognitive radio network has three modes of operation: the Underlay Paradigm, the Overlay Paradigm, and the Internetwork Paradigm. when the overlay mode is used, the secondary user is allowed to transmit data at the same time as the primary user, as long as it is within the range of the primary user tolerance, as long as it is within the range of the primary user's tolerance; and from the secondary user's perspective, The secondary user must reasonably control its transmit power to obtain a higher transmission rate as much as possible while ensuring that harmful interference is not generated for the primary user. Dynamic resource allocation (DRA) is therefore critical. The secondary user dynamically adjusts the transmission power, the transmission rate, the bandwidth, and even the antenna beam to obtain the best performance by using the channel state information (CSI) obtained by the secondary user, and at the same time, the service quality of the main link is ensured. In recent years, with the rapid development of the wireless network and the continuous diversification of the services, such as the Internet protocol-based language, video and other wireless services Add. These services are very sensitive to network transmission time delay and need to meet certain time-delay quality of service (QoS) therefore, meeting the QoS requirement of different service time delay becomes the heat of the current wireless network research Point. In particular, cognitive wireless networks, which are more challenging to meet different time-delay QoS requirements due to spectrum sharing and interference power constraints Therefore, it is important to study the power control strategy with time delay constraint in the cognitive network In this paper, based on the effective capacity model, the power control strategy based on time delay constraint of cognitive radio network is studied, and the optimization parameters (effective capacity or interference power) and time delay constraint in different fading environments are analyzed. According to the invention, the capacity performance of the cognitive radio system is improved while the time delay of the secondary user is guaranteed by the diversity reception, and the generation of the primary user by the secondary user is reduced by using the OFDM multi-subcarrier transmission, The main research work The results are as follows: (1) The optimal work of the single-antenna cognitive radio system with time-delay QoS constraint is first studied. Rate control strategy. The proposed power control strategy is to maximize the effective capacity of the cognitive radio system and is limited to the average dry In this paper, the power control expression and the effective control of the Nakagami fading channel under the optimal power control are derived. The paper studies the cognitive radio system under different time delay with different fading channels (including different fading types and channel gains). The results show that the characteristics of the interference channel (the secondary user transmitting end and the receiving end of the main user) play a decisive role in the capacity performance of the cognitive system when the delay constraint is more relaxed; when the delay constraint is more strict, the effect of the interference channel characteristics on the capacity performance of the cognitive radio system in response to step-by-step reduction, that characteristic of the cognitive channel (between the secondary-user-transmitting end and the secondary-user-receiving end) will play a role in the capacity of the cognitive radio system, On the basis of the above-mentioned research, the main number of users is extended from one to n, and the system capacity and n when the cognitive radio system meets the requirements of different time-delay QoS is studied. The results show that the effective capacity decreases with the increase of n when the time-delay constraint is looser, and the time-delay constraint becomes more and more strict, In addition, that multi-diversity branch, the effective capacity and the time delay of the multi-antenna cognitive radio system are studied. The relationship between the constraints. Maximum Ratio combining is used for the secondary user receiving end The results show that the increase of the antenna diversity branch can improve the cognition. The capacity performance of the channel. In particular, when the delay constraint is more strict, the effective capacity is increased. the benefits are significantly improved, so the multi-antenna configuration is more suitable In this paper, the time-delay QoS constraint of the single-carrier cognitive radio system is studied firstly. the proposed power control strategy minimizes the primary user while ensuring the time delay qos constraints required to reach the traffic flow, The average interference power of the receiving end is derived. The lower level of the Nakagami fading environment is derived. The closed solution of the average interference power is analyzed. The time-delay constraints under different fading conditions are analyzed. The relationship between the interference power and the interference power. The results show that the time delay and the interference power there is an inherent trade-off. the more stringent the time delay constraint requirements of the secondary user, it will the larger the interference power generated by the user, especially when the cognitive channel is in deep fading, the interference power is greatly increased by the increase of the constraint index value at any time; and when the quality of the cognitive channel is good, the interference power can delay the increase of the constraint index value at any time, In this paper, the time-delay QoS of the OFDM multi-carrier cognitive radio system is studied. the proposed power distribution scheme minimizes the allocated sub-mail while ensuring the secondary user's time-delay qos constraints, The sum of the total average interference power of the channel. From the frequency domain angle analysis, the power distribution strategy is from large to small according to the ratio of the cognitive sub-channel to the interference sub-channel power The power is assigned in a water-injection manner. From the time-domain angle analysis, this policy is based on The time delay QoS constraint index is analyzed. The interference work in the case of different sub-channel numbers is analyzed. The relationship between the rate and the delay constraint. The results show that the number of sub-channels can be reduced by increasing the number of sub-channels when the time-delay constraint is more stringent. and therefore, the power distribution based on the multi-carrier CR is more strict than that of the single-carrier CR based on the power control of the single-carrier CR, The secondary user accesses the primary user network. (3) the non-ideal channel state information (Imperuse CSI) is studied ) The effective capacity performance of the cognitive radio system. The secondary user receives the MRC diversity at the receiving end and uses the minimum mean square error criterion (Minimum Mean Square Erro). R, MMSE) estimation of channel error. The work of non-ideal CSI based on average interference power constraint is obtained. The results show that the channel estimation error leads to a decrease in the capacity of the cognitive radio system, especially In addition, that increase of the diversity branch not only can improve the capacity gain, but also can also be compensated. Capacity loss due to channel estimation error. Non-ideal CSI is analyzed The effective capacity gain based on the interference interruption constraint is obtained. The power control under the most severe interference interruption constraints is obtained. The lower bound expression of the strategy and the corresponding effective capacity. The effective capacity and the dry capacity are analyzed. The relationship between the interference interrupt threshold and the estimated error is estimated. The results show that the interference-based interrupt constraint is very small compared with the strict peak-interference power constraint. a disturbance can result in a larger capacity gain, in particular, The capacity gain is more significant when the delay constraint is more relaxed. In addition, for non-ideal CSI, only a certain degree of interference interruption is allowed, and based on the peak interference interruption constraint and the average interference power,
【學位授予單位】：華南理工大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN92

【參考文獻】

相關期刊論文 前4條

1 劉爽;朱凱;董宸;;基于PLC一維極軸自動控制的對日跟蹤系統(tǒng)[J];工業(yè)控制計算機;2010年01期

2 XU Ding;FENG ZhiYong;ZHANG Ping;;Effective capacity of delay quality-of-service constrained spectrum sharing cognitive radio with outdated channel feedback[J];Science China(Information Sciences);2013年06期

3 魏急波;王杉;趙海濤;;認知無線網(wǎng)絡:關鍵技術與研究現(xiàn)狀[J];通信學報;2011年11期

4 徐勇軍;趙曉暉;;基于QoS和干擾溫度約束的多用戶認知無線電網(wǎng)絡最優(yōu)功率分配(英文)[J];中國通信;2013年10期

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