發(fā)布時間：2018-11-05 16:50

【摘要】：隨著信息科學技術(shù)的蓬勃發(fā)展,一種新的無線網(wǎng)絡(luò)技術(shù)  無線Mesh網(wǎng)絡(luò)(Wireless Mesh Networks,WMNs)受到了眾多用戶的青睞,它擁有更高的吞吐率、更低的時延以及更好的可靠性。然而,由于無線網(wǎng)絡(luò)帶寬資源的緊缺,如何更加合理的用較少的帶寬為更多的用戶服務(wù),已經(jīng)成為無線領(lǐng)域研究的重要方向。本文對WMNs中的組播路由(Multicast Routing)和時隙分配(Time Slot Assignment)兩個問題進行了深入分析研究,提出了考慮無線干擾的組播路由算法和時隙分配算法,以降低網(wǎng)絡(luò)時延,提高系統(tǒng)吞吐量。本文首先研究了WMNs中的組播路由問題。隨著網(wǎng)絡(luò)規(guī)模的膨脹,網(wǎng)絡(luò)帶寬資源緊缺,需要設(shè)計性能優(yōu)異的路由算法來增大吞吐量,降低時延,從而節(jié)省帶寬資源。然而由于無線網(wǎng)絡(luò)的干擾的存在,數(shù)據(jù)傳輸時延可能有好有壞,因此需要找出具有最小時延的路徑。本文首先對計算組播樹最小端到端時延的問題進行建模,將其抽象成一個整數(shù)線性規(guī)劃模型;由于整數(shù)線性規(guī)劃模型是NP問題,本文又提出了一種組播樹時延的估算方法,以保證在多項式時間復(fù)雜度內(nèi)求出組播樹的時延;之后提出了一種基于最小時延的組播路由算法;最后進行了大量的仿真,將本文提出的新的路由算法和傳統(tǒng)算法進行了對比,證明了本文介紹的算法較之傳統(tǒng)算法更加有效。隨著網(wǎng)絡(luò)規(guī)模的不斷增長,網(wǎng)絡(luò)中分組傳輸所需的時隙數(shù)目急劇增加,從而導致網(wǎng)絡(luò)時延變大,系統(tǒng)吞吐量降低。為了解決無線網(wǎng)絡(luò)中時隙分配不公平而導致的數(shù)據(jù)傳輸效率下降問題,本文提出了一種基于置信度傳輸(Belief Propagation,BP)實現(xiàn)網(wǎng)絡(luò)時隙分配的算法。首先建立因子圖模型,再通過BP算法來計算邊緣概率,之后舉例對算法進行了詳細說明;最后進行了仿真驗證,仿真中可以看出本文提出的算法能夠有效實現(xiàn)時隙復(fù)用,并滿足公平性。本文提出的兩種算法均能提升網(wǎng)絡(luò)性能,具有實踐意義。
[Abstract]:With the rapid development of information science and technology, a new wireless network technology, wireless Mesh network (Wireless Mesh Networks,WMNs) is favored by many users. It has higher throughput, lower delay and better reliability. However, due to the shortage of bandwidth resources in wireless networks, how to use less bandwidth to serve more users has become an important research direction in wireless field. In this paper, two problems of multicast routing (Multicast Routing) and slot allocation (Time Slot Assignment) in WMNs are deeply analyzed and studied. The multicast routing algorithm and slot allocation algorithm considering wireless interference are proposed to reduce the network delay. Improve system throughput. In this paper, we first study the multicast routing problem in WMNs. With the expansion of network scale and the shortage of network bandwidth resources, it is necessary to design excellent routing algorithms to increase throughput and reduce delay, thus saving bandwidth resources. However, due to the interference of wireless networks, the data transmission delay may be good or bad, so it is necessary to find out the path with the minimum delay. Firstly, the problem of computing the minimum end-to-end delay of multicast tree is modeled and abstracted into an integer linear programming model. Since the integer linear programming model is a NP problem, this paper proposes a method to estimate the delay of multicast tree in order to solve the delay of multicast tree within polynomial time complexity, and then proposes a multicast routing algorithm based on minimum delay. Finally, a large number of simulations are carried out, comparing the new routing algorithm proposed in this paper with the traditional algorithm, which proves that the algorithm presented in this paper is more effective than the traditional algorithm. With the increasing of network scale, the number of time slots needed for packet transmission in the network increases dramatically, which leads to the increase of network delay and the decrease of system throughput. In order to solve the problem of data transmission efficiency decline caused by unfair slot allocation in wireless networks, this paper proposes an algorithm based on confidence degree transmission (Belief Propagation,BP) to implement slot allocation in wireless networks. Firstly, the factor graph model is established, then the edge probability is calculated by BP algorithm, and then the algorithm is explained in detail by an example. Finally, the simulation results show that the proposed algorithm can effectively realize slot multiplexing and meet the fairness. The two algorithms proposed in this paper can improve the network performance and have practical significance.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN929.5

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