計(jì)算機(jī)畢業(yè)設(shè)計(jì)外文翻譯---網(wǎng)絡(luò)體系結(jié)構(gòu)和關(guān)鍵的設(shè)計(jì)要素(文件)
【正文】 uting protocols can significantly improve the performance of WMNs. Broadband and QoS. Different from classical ad hoc works, most applications of WMNs are broadband services with heterogeneous QoS requirements. Thus, in addition to endtoend transmission delay and fairness, more performance metrics, such as delay jitter, aggregate and pernode throughput, and packet loss ratios, must be considered by munication protocols. Security. Although many security schemes have been proposed for wireless LANs in recent years, they are still not fully applicable for WMNs. For instance, there is no centralized trusted authority to distribute a public key in a WMN due to the distributed system architecture. The existing security schemes proposed for ad hoc works can be adopted for WMNs. However, most of the security solutions for ad hoc works are still not mature enough to be implemented practically. Moreover, the different work architectures between WMNs and ad hoc works usually render a solution for ad hoc works ineffective in WMNs. Ease of Use. Protocols must be designed to enable the work to be as autonomous as possible. In addition, work management tools need to be developed to efficiently maintain the operation, monitor the performance, and configure the parameters of WMNs. These tools, together with the autonomous mechanisms in working protocols, enable rapid deployment of WMNs. Compatibility and Interoperability. In WMNs it is a default requirement to support work access for both conventional and mesh clients. Therefore, WMNs need to be backward patible with conventional client nodes. This demands that mesh routers need to be capable of integrating heterogeneous wireless works. Conclusion Although WMNs can be built up based on existing technologies, field trials and experiments with existing WMNs prove that the performance of WMNs is still far below expectations. As explained throughout this article, there still remain many research problems. Among them, the most important and urgent ones are the scalability and the security. Scalability. Based on existing MAC, routing, and transport protocols, work performance is not scalable with either the number of nodes or the number of hops in the work. This problem can be alleviated by increasing the work capacity through using multiple channels/radios per node or developing wireless radios with higher transmission speed. However, these approaches do not truly enhance the scalability of WMNs, because resource utilization is not actually improved. Therefore, in order to achieve scalability, it is essential to develop new MAC, routing, and transport protocols for WMNs. Security. WMNs are vulnerable to security attacks in various protocol layers. Current security approaches may be effective to a particular attack in a specific protocol layer. However, there still exists a need for a prehensive mechanism to prevent or counter attacks in all protocol layers. Moreover, selforganization and selfconfiguration capability is a desired feature in WMNs. It requires protocols in WMNs to be distributive and collaborative. However, current WMNs can only partially realize this objective. Furthermore, current WMNs still have very limited capabilities of integrating heterogeneous wireless works, due to the difficulty in building multiple wireless interfaces and the corresponding gateway/bridge functions in the same mesh Router. In spite of these open research problems, we believe that WMNs will be one of the most promising technologies for nextgeneration wireless working. 無(wú)線 Mesh 網(wǎng)絡(luò)調(diào)查 IAN F.
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