Research Paper On Gateway Inc
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Other tasks Printer format Order by fax Currency converter. First Research, Inc. January, Single User License:. Evolution of these networks over time indicates the need for algorithms which can operate based on their dynamic nature. Wireless mesh networks provide Intranet and Internet access for different applications in various environments. It is expected that the traffic load will be high on these networks. As gateway nodes are responsible for the traffic load transmission, gateway selection is known as one of the important research issues in that it can lead to optimized use of the network capacity and reduce congestion effects.
In addition, utilizing multi-radio multi-channel archi- tecture is one of the promising methods for increasing performance and decreasing interference. Channel assignment determines the most appropriate channel-radio asso- ciations for transmitting and receiving data through different channels simultaneously. Taking into account this architecture, this paper was written to propose a distributed gateway selection algorithm along with a cross-layer concept which predicts envi- ronment dynamics by learning automata.
Experimental results demonstrate that the proposed method in various configurations on average improves packet delivery ratio Jahanshahi mjahanshahi iauctb. Parvanak et al. This network is organized in a three-level architecture, including application, infras- tructure and Internet. Mesh routers are usually immobile nodes without power constraint that form a multi-hop wireless infrastructure between mesh clients and Internet gateways. Each mesh router not only operates as a host but also as a router, forwards data packets on behalf of other mesh nodes that may not be within direct wire- less transmission range of their destinations [1, 2].
The issue of interference reduction in MRMC WMNs is typically dealt with by developing a channel assignment strategy which effectively specifies the most appropriate channel-radio associations. However, channel assignment brings about its own complications; in effect, an additional con- straint ought to be satisfied for network connectivity in MCMR WMNs as compared to the conventional wireless networks; more specifically, two nodes are considered neighbors only if: 1 they are located within the transmission range of each other and; 2 there exists a common channel assigned to the radios of both nodes [3, 4].
To increase the capacity and performance of WMNs, mesh routers can be equipped with multiple radios, each tuned on a different channel. Additionally, each mesh router is equipped with a control radio interface to exchange control packets in the net- work. Using the control radio interface separates the network traffic and also speeds up packet processing in the mesh nodes . Due to the limited number of channels supported by radios, network performance is highly impacted by frequency interfer- ences . Hence, it is necessary to propose an appropriate channel selection scheme to minimize interference and congestion, thereby reducing packet loss and delay. Gateway nodes are routers with additional features such as higher buffer size, wired and wireless interfaces, etc.
Gateway nodes usually are directly connected to a wired network. In many applications, most of the traffic load is conducted to the gateway Fig. Therefore, traffic aggregation occurs on paths leading to the gateway nodes and causes congestion. One of the most important considerations is selecting proper gate- way in these networks and sending traffic to them [1, 7]. Proper gateway selection has a considerable impact on the WMN efficiency and robustness. In this paper, the pro- posed LA based gateway selection algorithm LAGS selects the gateway nodes based on their performance impact on network traffic and controls which gateway nodes the traffic should be sent to.
The proposed method selects the gateway nodes by LA in a distributed fashion on each mesh router. In addition, LAGS selects the proper channel based on LA by determining the most appropriate channel-radio associations. There- fore, LAGS decreases interference and improves efficiency which results in desirable utilization of network capacity. Existence of two approaches, gateway selection in each router on the network layer and channel assignment in each radio on the MAC layer, is according to cross-layer concept.
Since the joint gateway selection and chan- nel assignment problem is known as NP-hard, use of operation research OR methods is not efficient for high dimensions of the given problem in polynomial time order; therefore it is reasonable to apply LA converging to sub-optimal solution. This paper is organized as follows: In Sect. The theory of LA along with its interaction with the stochastic environment is briefly reviewed in Sect. In Sect. Section 6 presents the conclusion of the paper. However, they have not considered MRMC architecture which is one of the promising methods for improving performance.
Therefore, these studies are not compared with the method proposed in this paper. Some studies  have just considered the dis- tance to gateway nodes which leads to performance reduction and the traffic load being unbalanced among gateway nodes as some gateway nodes have low load and others experience overload and congestion states. Hop count metric is not a desirable choice as it might be a shorter path between the source node and gateway node that have high interference and high packet loss.
In  a centralized gateway selection algorithm with a proactive approach in single-radio single-channel SRSC multi-hop wireless networks was introduced. In this study, wireless hosts had the same hop count to gate- ways. Each end host selected its default gateway by a predefined cost function based on load balancing. This study not only considered traffic intensity and load balancing, but also considered wireless channel interference around the gateways. The results of this study indicated that the proposed scheme, by considering two cost functions, increases gateway throughput. Although this scheme used hop count threshold and had limited gateway selection policy to a subset of gateway nodes, it used hop count metric for gateway selection, which may cause performance reduction and the traffic load being unbalanced.
In some studies, such as , gateway switching occurs heuristically and in a centralized fashion; it does not switch to a better gateway and path. Besides, these studies did not utilize learning approaches which consider the previous state of the network environment for proper gateway and path selection. In  proposed a link-state and distributed algorithm in MRMC, multi-tier wireless mobile ad-hoc networks MANET with a proactive approach for dynamic gateway selection in each sub-network.
Obviously, hop count and interference have a trade-off. This study is trying to compromise between them. To enhance network responsibility in critical situations, gateway nodes are categorized in two classes of active and backup gate- ways. However, adding, removing or replacing a gateway node disrupts the network until nodes reconfigure successfully and paths converge again. In addition, by adding backup gateway nodes over time, proper sub-optimal solution cannot be achieved. This list has been ranked according to a combination of link costs and congestion costs with inspired by enhanced interior gateway routing protocol EIGRP.
On the other hand, the gateways cost is determined in this list for allocating them to sub-networks in the future. Some studies [17, 19, 20] did not take path state between the wireless routers and gateway nodes into account and only considered traffic load. The aim is to achieve load balancing among different gateway nodes. Considering the gateway load as the sole metric for selecting the best route is not a good idea.
In fact, there are some cases in which the gateway load is low, however, the interference and packet loss on the paths leading to the gateway is high. Some other studies  examined a distributed algorithm, including gateway discovery, route selection and gateway selection with a proactive approach in SRSC WMNs. Best gateway selection BGS algorithm pre- sented in this study used a combination of metrics including gateway load and ETX.
In addition, this study calculated a logical estimate of the interference and link quality in order to select the path to gateway nodes. However, it measured the approximate expected link quality ELQ just according to ETX without considering other effective parameters on the link quality. Expected transmission time ETT and ETX [21, 22] are routing metrics that only consider delivery ratio without concerning about inter- ference among links. It led to load imbalance, because these metrics do not have true perception of traffic load.
In this study, gateway current load was approximated based on previous estimates and processing traffic volume. Besides, this algorithm ensured that the hosts did not switch among the gateway nodes quickly. When a host receives an advertisement from gateway j with lower load, it can adjust gateway j as its new gateway if it uses gateway i at least for a while. Moreover, in the aforementioned conditions, a node just switches the gateway nodes with a specific gateway-switching probability to avoid switch fluctuations among gateway nodes.
Some studies [6, 23] on gateway selection problem only attended to load balancing and did not consider inter-channel interference and advertisements overhead. In this study, a cost function was presented to minimize total traffic among gateways in order to reduce congestion. Plus, to avoid interference, gateway selection and optimization of gateway placement and channel assignment algorithms were evaluated. In this scheme, a simple algorithm was used to select a number of gateway nodes; however, communication patterns in a real network and the method of using selected gateways were not considered.
In particular, this study used the hop count metric and the number of under-service hosts for all gateways. These metrics do not consider the interference among different gateways and hosts traffic loads demands difference. This scheme considers gateway load, ETX and interference metrics to select the best path in terms of path quality calculation and the best gateway selection with proper load index LI. It not only distributes the traffic load among gateway nodes, but also reduces traffic passing through each gateway. However, due to only considering traffic load and inattention to distance hop count from the gateway nodes, it caused reduced total network per- formance.
In some studies such as  proposed a distributed meta-heuristic method in MRMC WMNs for solving the gateway placement problem and load balancing. This study presented a genetic algorithm to divide WMN into limited-to-the radius clusters, under relay load and cluster size constraints. It maintains service quality parameters such as delay and bandwidth. Within each cluster, the cluster head serves as a gateway.
A spanning tree rooted at the gateway is used for traffic forwarding. Each node is associated with a tree and can be connected to another tree as an alter- native path in case of path failure. The RLBPR algorithm learns a proper gateway selection and routing policy depending on various optimization metrics such as packet loss ratio, interference and gateway load. This method was inspired from BP2BG  and learns the best neighbor and best gateway for sending incoming data packets to them by gateway selection and next hop selection algorithms as well as a learning agent in each router.
In  presented the conflict graph CG concept for channel assignment problems in a multi-radio infrastructure and used it to model the interference among mesh routers. In this scheme, a multi-radio conflict graph MCG forms based on interference among links, then channels were initially assigned to radios greedily via breadth-first search BFS. The search begins with links emanating from the gateway node by giving channel assignment priority to links starting from the gateway and then in decreasing levels of priority to links fanning outward towards the edge of the network.
It is the first algorithm that has considered inter-flow interference. Recently, a cross-layer concept optimization framework has been proposed for joint channel assignment and multicast throughput maximization in MCMR WMNs. Then, the resultant channel assignment scheme was utilized in the second phase for throughput maximization within an iterative optimization framework based on Lagrange relaxation and primal problem decomposition . This study uses LA in order to select the appropriate gateway node to send traffic. The strategy of this paper is to associate nodes with a particular gateway, therefore a domain of nearest gateways will be created for each router.
Every time that a router wants to send data, it will choose a gateway from its domain by using its LA to send data. In general, the proposed algorithm associates each router with a domain of its nearest gateways. Resume writing agencies an essay about computer science , essay on pigeons in hindi popular paper editing site for school. Essay of marriage and single life the resume ru, buy math dissertation bellow essay sample latex thesis template sylvia plath poetry essay introduction, create thesis statement descriptive essay. Cheap analysis essay editor websites usa research paper topics about country music sample resume handyman how to write alphabets in chinese alphabet symbols example company overview business plan: introduction on global warming essayWords to use when writing a compare and contrast essay professional writing courses cheap admission essay on hillary clinton.
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