【摘要】：無線Mesh網(wǎng)絡(luò)WMNs(Wireless Mesh Networks)能擴(kuò)展現(xiàn)有無線網(wǎng)絡(luò)的覆蓋范圍,是構(gòu)建寬帶無線接入網(wǎng)絡(luò)的關(guān)鍵組網(wǎng)類型,近年來受到了學(xué)術(shù)界和業(yè)界的廣泛關(guān)注。WMNs的網(wǎng)絡(luò)容量隨并行傳輸間干擾的增加而迅速下降。有效的路由與信道分配策略是提升網(wǎng)絡(luò)容量的有效方案,它們能顯著提升WMNs的整體性能。有效的信道分配方案能保證有通信需求的鄰近節(jié)點運行在相同信道上;有效的路由選擇策略從多條可行路徑中選擇出滿足端到端服務(wù)質(zhì)量要求的最優(yōu)路徑。信道分配決定了節(jié)點在通信過程中可能受到的干擾,也決定了源節(jié)點與目的節(jié)點之間的可行路徑集合。路由度量是路由計算與選擇的基礎(chǔ),其設(shè)計的優(yōu)劣直接決定了源節(jié)點與目的節(jié)點間通信路徑的好壞,進(jìn)而影響網(wǎng)絡(luò)整體性能。WMNs中節(jié)點間通信方式分為單播和多播兩種,路由與信道分配策略的設(shè)計要充分考慮單播與多播通信的特點,才能充分發(fā)揮WMNs的優(yōu)勢。目前針對WMNs路由與信道分配的研究,雖然取得了一定進(jìn)展,但是仍存在諸多問題。其中主要的問題有:為鄰近的傳輸節(jié)點分配正交信道,由此引入的同信道干擾會阻止節(jié)點的并行傳輸并引發(fā)網(wǎng)絡(luò)吞吐量下降;采用實測方法估計部分重疊信道POCs(Partially Overlapped Channels)干擾范圍,獲得的測量結(jié)果可移植性差;信道分配只考慮骨干鏈路,忽略接入鏈路,得到的信道分配結(jié)果無法應(yīng)用于端到端的數(shù)據(jù)流傳輸;路由度量設(shè)計考慮單一網(wǎng)絡(luò)業(yè)務(wù)類型、忽略網(wǎng)關(guān)節(jié)點的選擇、分開描述各類干擾導(dǎo)致引入可調(diào)參數(shù);多播路由與信道分配研究大多面向單個多播會話,只為一個會話優(yōu)化網(wǎng)絡(luò)資源使用,忽略網(wǎng)絡(luò)整體負(fù)載均衡。本文針對現(xiàn)有研究中存在的主要問題,提出使用頻譜上有交疊的信道即POCs來提升網(wǎng)絡(luò)性能的路由與信道分配方案。從單播路由度量設(shè)計與POCs信道分配、多播路由與POCs信道分配方面入手解決數(shù)據(jù)流的路由與信道選擇問題,提出了綜合考慮POCs WMNs特點的路由與信道分配策略,為單播和多播數(shù)據(jù)流選擇合理的傳輸路徑并為路徑上的鏈路分配合理的信道,實現(xiàn)高吞吐量數(shù)據(jù)傳輸。本文的主要創(chuàng)新工作可以總結(jié)為以下五方面:(1)使用理論推導(dǎo)方法獲取對應(yīng)不同信道間隔的POCs干擾范圍,解決實測方法估計干擾范圍的準(zhǔn)確性和可移植性問題。使用雙徑地面?zhèn)鞑ツＰ湍M開放空間環(huán)境中信號的路徑損耗,用歸一化的發(fā)送和接收端功率譜密度的卷積量化POCs干擾范圍的縮減,得出理想發(fā)送信號頻率模板下的POCs干擾范圍和使用不同滾降因子的升余弦滾降濾波器的POCs干擾范圍。由推導(dǎo)結(jié)果可以看到POCs干擾范圍隨信道間隔的增大而減小,這是POCs能夠得到應(yīng)用的基礎(chǔ)。(2)提出端到端POCs信道分配方案,實現(xiàn)有效的端到端數(shù)據(jù)流傳輸。使用綜合考慮鏈路位置、鏈路負(fù)載和干擾鄰居數(shù)的Rank值確定鏈路的信道分配次序,賦予擁塞可能性高的鏈路更高的信道分配優(yōu)先權(quán)。考慮骨干鏈路與接入鏈路使用同頻段信道和異頻段信道進(jìn)行通信的兩種情況,根據(jù)節(jié)點度或鏈路負(fù)載進(jìn)行鄰居—接口綁定,確定相鄰節(jié)點間通信使用的接口;以最小化網(wǎng)絡(luò)干擾為目標(biāo)進(jìn)行接口—信道綁定,確定相鄰節(jié)點間通信使用的信道。當(dāng)網(wǎng)絡(luò)中正交信道數(shù)量不足時,可以充分利用POCs增加骨干并行傳輸數(shù);當(dāng)網(wǎng)絡(luò)中有足夠的正交信道能消除骨干鏈路之間的干擾時,盡量避免使用POCs。(3)設(shè)計多網(wǎng)關(guān)POCs干擾統(tǒng)一描述路由度量,解決POCs WMNs中數(shù)據(jù)流的路由選擇問題。該路由度量使用等效帶寬準(zhǔn)確捕捉POCs WMNs中的物理干擾、邏輯流內(nèi)干擾和邏輯流間干擾對數(shù)據(jù)傳輸?shù)挠绊?簡化路由度量表達(dá)式;根據(jù)不同業(yè)務(wù)類型,使用不同的路由度量表達(dá)式計算并選擇路由,指導(dǎo)數(shù)據(jù)包通過最優(yōu)網(wǎng)關(guān)和去向最優(yōu)網(wǎng)關(guān)的最優(yōu)路徑進(jìn)行傳輸;考慮網(wǎng)關(guān)對路由選擇的影響,避免網(wǎng)關(guān)附近形成容量瓶頸制約網(wǎng)絡(luò)的整體服務(wù)能力。(4)提出多播加權(quán)沖突圖模型建模面向混合業(yè)務(wù)的POCs干擾。多播加權(quán)沖突圖模型將起始于同一節(jié)點的一組鏈路視為一次傳輸,充分考慮多播的無線廣播優(yōu)勢;使用鏈路權(quán)重衡量鏈路間的干擾程度,充分考慮POCs干擾特性。(5)提出面向混合業(yè)務(wù)的聯(lián)合多播路由與POCs信道分配的二進(jìn)制規(guī)劃構(gòu)建和啟發(fā)式求解方案,從業(yè)務(wù)管理角度均衡網(wǎng)絡(luò)負(fù)載、優(yōu)化整體網(wǎng)絡(luò)資源使用。將節(jié)點負(fù)載均衡和信道負(fù)載均衡引入聯(lián)合問題的規(guī)劃構(gòu)建中,避免了某些鏈路高度擁塞而其他鏈路利用率低下的情況。由規(guī)劃構(gòu)建得出的最優(yōu)解可以作為評價其他集中式或分布式方案性能的基準(zhǔn)。啟發(fā)式方案通過比較各尚未被覆蓋的多播接收端到源節(jié)點的所有可行路徑的代價,從中不斷尋找代價最小的路徑構(gòu)建多播樹并為路徑上的鏈路分配信道,直到將所有多播接收端與源節(jié)點連接起來。啟發(fā)式方案能在多項式時間內(nèi)找到逼近最優(yōu)網(wǎng)絡(luò)性能的路由與POCs信道分配結(jié)果,可以應(yīng)用于實際。本文通過對WMNs路由與POCs信道分配問題的深入研究,提出利用POCs提升網(wǎng)絡(luò)性能的單播、多播路由與信道分配方案,克服了現(xiàn)有研究的局限性,實現(xiàn)了高效的端到端通信。研究成果有助于提升網(wǎng)絡(luò)整體性能,推動POCs在WMNs中的應(yīng)用。
[Abstract]:Wireless Mesh Networks (WMNs) can expand the coverage of the existing wireless network, and it is the key networking type to construct the broadband wireless access network. In recent years, the wireless Mesh Networks has received extensive attention from the academic community and the industry. The network capacity of the WMNs decreases rapidly with the increase of the interference between the parallel transmission. The effective routing and channel allocation strategy is an effective solution to improve the network capacity, which can significantly improve the overall performance of the WMNs. The effective channel allocation scheme can ensure that the neighboring nodes with communication requirements run on the same channel; the effective route selection strategy selects an optimal path satisfying the end-to-end service quality requirement from a plurality of feasible paths. The channel assignment determines the possible interference of the node in the communication process and also determines a set of feasible paths between the source node and the destination node. The routing metric is the basis of the route calculation and selection, and the design of the routing metric directly determines the communication path between the source node and the destination node, thereby affecting the overall performance of the network. The inter-node communication method in WMNs is divided into two types: unicast and multicast. The design of the routing and channel allocation strategy should take full account of the characteristics of unicast and multicast communication, so as to give full play to the advantages of WMNs. At present, the research on the route and channel assignment of WMNs, although some progress has been made, there are still many problems. The main problem is that the orthogonal channel is allocated to the adjacent transmission nodes, the co-channel interference introduced by the method can prevent the parallel transmission of the nodes and cause the network throughput to drop, and the interference range of the partially overlapped channels POCs is estimated by the measured method. the obtained measurement result is poor in portability; only the backbone link is considered in the channel allocation, the access link is ignored, the obtained channel allocation result cannot be applied to the end-to-end data flow transmission, the routing metric design takes into account the single network service type, and the selection of the gateway node is ignored, Separate description of various interference results in the introduction of tunable parameters; most of the multicast routing and channel allocation studies face a single multicast session, only one session optimizes network resource usage, and ignores the overall network load balance. In this paper, aiming at the main problems existing in the existing research, a routing and channel allocation scheme is proposed to improve the network performance using the overlapping channels, i.e., POCs. From the aspects of unicast route metric design and POCs channel allocation, multicast routing and POCs channel allocation, the problem of routing and channel selection of data flow is solved, and the strategy of routing and channel allocation considering the characteristics of POCs WMNs is proposed. A reasonable transmission path is selected for the unicast and multicast data streams and a reasonable channel is allocated for the links on the path, and high-throughput data transmission is realized. The main innovative work of this paper can be summarized in the following five aspects: (1) the theoretical derivation method is used to obtain the interference range of the POCs corresponding to different channel intervals, and the accuracy and the portability of the interference range are estimated by the measured method. the path loss of a signal in an open space environment is simulated by using a double-diameter ground propagation model, and the reduction of the interference range of the POCs is quantified by the convolution of the normalized transmission and receiving end power spectral density, It is concluded that the POCs interference range under the ideal transmission signal frequency template and the POCs interference range of the raised cosine roll-down filter using different roll-off factors are obtained. The result of the derivation can see that the interference range of the POCs decreases with the increase of the channel spacing, which is the basis for the application of the POCs. (2) An end-to-end POCs channel allocation scheme is proposed, and the effective end-to-end data stream transmission is realized. The channel allocation order of the link is determined using the Rank value combining the link position, the link load, and the interference neighbor number, and the channel allocation priority that is higher than the link with which the congestion probability is high is given. considering the two cases of communication between the backbone link and the access link using the same frequency band channel and the different frequency band channel, the neighbor base interface binding is carried out according to the node degree or the link load, the interface used by the communication among the adjacent nodes is determined, A channel used for inter-node communication is determined. When the number of orthogonal channels in the network is not enough, the POCs can be fully utilized to increase the number of parallel transmission of the backbone; when there is enough orthogonal channel in the network to eliminate the interference between the backbone links, the use of the POCs is avoided as much as possible. And (3) designing the multi-gateway POCs interference to uniformly describe the route metric and solving the routing problem of the data flow in the POCs WMNs. the route metric uses the equivalent bandwidth to accurately capture the physical interference in the POCs WMNs, the interference between the logic flow and the logical inter-flow interference on the data transmission, simplifies the routing metric expression, calculates and selects the route using different route metric expressions according to different service types, The guide data packet is transmitted through the optimal gateway and the optimal path to the optimal gateway; the influence of the gateway on the route selection is taken into account, and the capacity bottleneck of the gateway near the gateway is avoided to restrict the overall service capability of the network. And (4) a multicast weighted collision graph model is proposed to model the POCs interference for the mixed service. The multicast weighted collision graph model considers a group of links starting from the same node as one transmission, and fully considers the radio broadcast advantages of the multicast; the interference degree between the links is measured by using the link weight, and the interference characteristics of the POCs are fully taken into account. And (5) putting forward a binary plan construction and a heuristic solution scheme for the combined multicast routing and the POCs channel allocation for the mixed service, and balancing the network load from the service management angle and optimizing the use of the whole network resource. The node load balancing and the channel load balancing are introduced into the planning construction of the joint problem, and the situation that some link is highly congested and other link utilization rate is low is avoided. The optimal solution derived from the planning can be used as a benchmark for evaluating the performance of other centralized or distributed schemes. The heuristic scheme constructs the multicast tree and assigns a channel to the link on the path by comparing the cost of all possible paths to the source node that have not yet been covered, until all the multicast receiving ends are connected to the source node. The heuristic scheme can find the route to the optimal network performance and the POCs channel assignment result in the polynomial time, and can be applied to the practical application. In this paper, through the deep study of the distribution of the WMNs route and the POCs channel, a unicast, multicast routing and channel allocation scheme using the POCs to improve the network performance is proposed, and the limitation of the existing research is overcome, and the high-efficiency end-to-end communication is realized. The research results help to improve the overall performance of the network and promote the application of the POCs in the WMNs.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN929.5
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本文編號：2507633