異構(gòu)網(wǎng)絡(luò)垂直切換技術(shù)研究
發(fā)布時間：2018-07-21 16:06
【摘要】：在過去的十幾年中,無線通信網(wǎng)絡(luò)技術(shù)得到了迅猛地發(fā)展,涌現(xiàn)出了許多制式各異的網(wǎng)絡(luò)。如已經(jīng)演進到第4代的蜂窩通信網(wǎng)絡(luò)、組網(wǎng)靈活的個域網(wǎng)、高帶寬的WLAN以及覆蓋范圍較廣的WiMAX,這些不同技術(shù)規(guī)格的網(wǎng)絡(luò)在空間中重疊覆蓋,構(gòu)成了一個異構(gòu)網(wǎng)絡(luò)環(huán)境。這些網(wǎng)絡(luò)在覆蓋范圍、性能指標(biāo)等方面各有不同,同時不同網(wǎng)絡(luò)在業(yè)務(wù)支持性方面各有側(cè)重。未來無線通信網(wǎng)絡(luò)技術(shù)必然是朝著異構(gòu)網(wǎng)絡(luò)融合的方向前進,下一代網(wǎng)絡(luò)將是各種不同網(wǎng)絡(luò)并存、協(xié)同、互補地工作,這樣才能滿足用戶越來越多樣化的需求,發(fā)揮不同網(wǎng)絡(luò)的長處為用戶提供更高質(zhì)量的服務(wù)。垂直切換作為異構(gòu)網(wǎng)絡(luò)融合的基礎(chǔ)性技術(shù),吸引了眾多的學(xué)者參與研究。本文介紹了垂直切換技術(shù)的研究背景和國內(nèi)外的研究現(xiàn)狀,并分析了基于RSS的切換策略、基于QoS的切換策略等現(xiàn)有垂直切換算法的優(yōu)缺點。在此基礎(chǔ)上,本文針對網(wǎng)絡(luò)發(fā)現(xiàn)、觸發(fā)時刻和網(wǎng)絡(luò)選擇提出了以下改進算法:(1)提出了基于預(yù)測RSS變化率的分級周期掃描機制。垂直切換包括網(wǎng)絡(luò)發(fā)現(xiàn)、切換觸發(fā)、網(wǎng)絡(luò)選擇和切換執(zhí)行四個階段。在網(wǎng)絡(luò)掃描階段,算法通過預(yù)測RSS變化率來估計網(wǎng)絡(luò)環(huán)境變化的趨勢,并分級調(diào)整網(wǎng)絡(luò)發(fā)現(xiàn)的掃描周期。(2)提出了基于預(yù)測駐留時間的切換觸發(fā)算法。在切換觸發(fā)階段,算法對終端在網(wǎng)絡(luò)中的駐留時間進行預(yù)測,并結(jié)合切換耗時決定切換的觸發(fā)時刻。(3)提出了基于活動業(yè)務(wù)的網(wǎng)絡(luò)選擇算法。在單業(yè)務(wù)場景下,算法根據(jù)不同業(yè)務(wù)對于網(wǎng)絡(luò)屬性的要求,利用模糊層次分析法為各個單業(yè)務(wù)制定了相適應(yīng)的屬性權(quán)值,并通過收益函數(shù)方法來確定最優(yōu)網(wǎng)絡(luò)。在多業(yè)務(wù)重疊的應(yīng)用場景下,算法在保證活動業(yè)務(wù)關(guān)鍵屬性的權(quán)值不變的基礎(chǔ)上,重新分配其他屬性的權(quán)值,再利用收益函數(shù)確定重疊業(yè)務(wù)場景下的最優(yōu)網(wǎng)絡(luò)。本文最后利用MATLAB仿真平臺對提出的改進算法進行模擬驗證:(1)終端以0.5m/s至10m/s速度移動時,分級周期掃描機制平均可以比傳統(tǒng)固定周期掃描機制減少66%的掃描次數(shù);(2)基于預(yù)測駐留時間的切換觸發(fā)算法的掉話率比基于RSS的切換策略低12%,比基于遲滯電平的切換策略低10%,與復(fù)雜度較高的基于位置感知的切換策略相同;(3)在多業(yè)務(wù)重疊場景下,本文基于活動業(yè)務(wù)的網(wǎng)絡(luò)選擇算法在語音業(yè)務(wù)和電子郵件業(yè)務(wù)分別作為最高優(yōu)先級業(yè)務(wù)的場景下優(yōu)于基于業(yè)務(wù)優(yōu)先級的算法。而在視頻業(yè)務(wù)作為最高優(yōu)先級業(yè)務(wù)時,兩個算法表現(xiàn)出相同的切換性能。
[Abstract]:In the past ten years, wireless communication network technology has developed rapidly, and many networks of different standards have emerged. For example, the cellular communication network has evolved to the 4th generation, the flexible personal area network, the high-bandwidth WLAN and the wimax with a wide coverage range. These networks with different technical specifications overlap in space and form a heterogeneous network environment. These networks have different coverage and performance indicators, and different networks have different emphasis on service support. The future wireless communication network technology is bound to move towards the direction of heterogeneous network convergence, the next generation network will be a variety of different networks co-exist, cooperate, complementary work, so as to meet the needs of users more and more diverse. Give play to the strengths of different networks to provide users with higher quality services. As the basic technology of heterogeneous network convergence, vertical handoff has attracted many scholars to participate in the research. This paper introduces the research background of vertical handoff technology and the research status at home and abroad, and analyzes the advantages and disadvantages of existing vertical handoff algorithms such as RSS based handoff strategy, QoS based handover strategy and so on. On this basis, this paper proposes the following improved algorithms for network discovery, trigger time and network selection: (1) A hierarchical periodic scanning mechanism based on prediction of RSS rate is proposed. Vertical handoff consists of four phases: network discovery, handoff trigger, network selection and handover execution. In the phase of network scanning, the algorithm estimates the trend of network environment change by predicting the rate of RSS change, and adjusts the scanning period of network discovery. (2) A switching trigger algorithm based on predictive residence time is proposed. In the phase of handoff trigger, the algorithm predicts the terminal residence time in the network, and decides the trigger time of handoff in combination with the handover time. (3) an active service-based network selection algorithm is proposed. In the single-service scenario, according to the requirements of different services for network attributes, the fuzzy analytic hierarchy process (AHP) is used to determine the appropriate attribute weights for each single service, and the optimal network is determined by the method of revenue function. In the multi-service overlapped application scenario, the algorithm reassigns the weights of other attributes on the basis of keeping the weights of the key attributes of the activity business unchanged, and then uses the income function to determine the optimal network in the overlapped service scenario. Finally, the improved algorithm is simulated and verified by MATLAB simulation platform: (1) when the terminal moves from 0.5m/s to 10m/s, The hierarchical periodic scanning mechanism can reduce the scanning times by 66% compared with the traditional fixed period scanning mechanism. (2) the handoff trigger algorithm based on predictive residence time is 12% lower than the RSS based handoff strategy and lower than that based on hysteresis level. The handoff strategy is 10% lower than that of the high complexity location-aware handoff strategy. (3) in the multi-service overlapping scenario, In this paper, the network selection algorithm based on active services is superior to the one based on service priority in the scenario where voice service and email service are respectively the highest priority services. However, when video traffic is the highest priority service, the two algorithms exhibit the same handoff performance.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN92
[Abstract]:In the past ten years, wireless communication network technology has developed rapidly, and many networks of different standards have emerged. For example, the cellular communication network has evolved to the 4th generation, the flexible personal area network, the high-bandwidth WLAN and the wimax with a wide coverage range. These networks with different technical specifications overlap in space and form a heterogeneous network environment. These networks have different coverage and performance indicators, and different networks have different emphasis on service support. The future wireless communication network technology is bound to move towards the direction of heterogeneous network convergence, the next generation network will be a variety of different networks co-exist, cooperate, complementary work, so as to meet the needs of users more and more diverse. Give play to the strengths of different networks to provide users with higher quality services. As the basic technology of heterogeneous network convergence, vertical handoff has attracted many scholars to participate in the research. This paper introduces the research background of vertical handoff technology and the research status at home and abroad, and analyzes the advantages and disadvantages of existing vertical handoff algorithms such as RSS based handoff strategy, QoS based handover strategy and so on. On this basis, this paper proposes the following improved algorithms for network discovery, trigger time and network selection: (1) A hierarchical periodic scanning mechanism based on prediction of RSS rate is proposed. Vertical handoff consists of four phases: network discovery, handoff trigger, network selection and handover execution. In the phase of network scanning, the algorithm estimates the trend of network environment change by predicting the rate of RSS change, and adjusts the scanning period of network discovery. (2) A switching trigger algorithm based on predictive residence time is proposed. In the phase of handoff trigger, the algorithm predicts the terminal residence time in the network, and decides the trigger time of handoff in combination with the handover time. (3) an active service-based network selection algorithm is proposed. In the single-service scenario, according to the requirements of different services for network attributes, the fuzzy analytic hierarchy process (AHP) is used to determine the appropriate attribute weights for each single service, and the optimal network is determined by the method of revenue function. In the multi-service overlapped application scenario, the algorithm reassigns the weights of other attributes on the basis of keeping the weights of the key attributes of the activity business unchanged, and then uses the income function to determine the optimal network in the overlapped service scenario. Finally, the improved algorithm is simulated and verified by MATLAB simulation platform: (1) when the terminal moves from 0.5m/s to 10m/s, The hierarchical periodic scanning mechanism can reduce the scanning times by 66% compared with the traditional fixed period scanning mechanism. (2) the handoff trigger algorithm based on predictive residence time is 12% lower than the RSS based handoff strategy and lower than that based on hysteresis level. The handoff strategy is 10% lower than that of the high complexity location-aware handoff strategy. (3) in the multi-service overlapping scenario, In this paper, the network selection algorithm based on active services is superior to the one based on service priority in the scenario where voice service and email service are respectively the highest priority services. However, when video traffic is the highest priority service, the two algorithms exhibit the same handoff performance.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN92
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