计算机毕业设计外文翻译---网络体系结构和关键的设计要素(编辑修改稿)

计算机毕业设计外文翻译---网络体系结构和关键的设计要素(编辑修改稿)内容摘要：

nd configuration, which significantly decreases the load of mesh clients and other end nodes. • Mobility of end nodes is supported easily through the wireless infrastructure. •Mesh routers integrate heterogeneous works, including both wired and wireless. Thus, multiple types of work access exist in WMNs. •Powerconsumption constraints are different for mesh routers and mesh clients. •WMNs are not standalone and need to be patible and interoperable with other wireless works. Therefore, WMNs diversify the capabilities of adhoc works instead of simply being another type of ad hoc additional capabilities necessitate new algorithms and design principles for the realization of WMNs. Critical Design Factors The critical factors influencing the performance of WMNs are summarized as follows. Radio Techniques. Many approaches have been proposed to increase capacity and flexibility of wireless systems in recent years. Typical examples include directional and smart antennas, multiple input multiple output (MIMO) systems,and multiradio/multichannel systems. To further improve the performance of a wireless radio and control by higher layer protocols, more advanced radio technologies, such as reconfigurable radios, frequency agile/cognitive radios, and even software radios, have been used for wireless munication. Although these radio technologies are still in their infancy, they are expected to be the future platform for wireless works due to their dynamic control capability. These advanced wireless radio technologies all require a revolutionary design in higherlayer protocols,especially MAC and routing protocols. Scalability. Scalability is a critical requirement of support of this feature, the work performance degrades significantly as the work size increases. For example, routing protocols may not be able to find a reliable routing path, transport protocols may loose connections, and MAC protocols may experience significant throughput reduction. To ensure the scalability in WMNs, all protocols from the MAC layer to the application layer need to be scalable. Mesh Connectivity. Many advantages of WMNs originate from mesh connectivity. To ensure reliable mesh connectivity,work selforganization and topology control algorithms are needed. Topologyaware MAC and routing 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 paramet。