在一个大型的网络信息应用系统中,存在着各种各样的资源和应用.不同的用户对于不同的资源,访问权限是不一样的,目前,对于这个问题的解决,主要是通过不同的访问控制机制来实现的,从而导致了管理、应用复杂,且成本高.针对这一问题,提出了...在一个大型的网络信息应用系统中,存在着各种各样的资源和应用.不同的用户对于不同的资源,访问权限是不一样的,目前,对于这个问题的解决,主要是通过不同的访问控制机制来实现的,从而导致了管理、应用复杂,且成本高.针对这一问题,提出了基于LDAP和R ad ius的统一资源访问控制机制,可以对不同的资源、不同的应用及使用者进行统一的管理.同时作者结合实际开发,提出了一个基于开放源代码系统的、可行的、稳定的认证平台及其所涉及的相关技术及方案,具有很强的实践性.展开更多
A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) i...A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) in a cluster, which is revealed by formulating resource allocation as a network utility maximization problem. Then, by maximizing the total network utility with constrains of minimizing collision probability, the optimal value of CW (Wopt) can be computed according to the number of sensor nodes. The new backoff algorithm uses the common optimal value Wopt and leads to fewer collisions than binary exponential backoff algorithm. The simulation results show that the proposed algorithm outperforms standard 802.11 DCF and S-MAC in average collision times, packet delay, total energy consumption, and system throughput.展开更多
文摘在一个大型的网络信息应用系统中,存在着各种各样的资源和应用.不同的用户对于不同的资源,访问权限是不一样的,目前,对于这个问题的解决,主要是通过不同的访问控制机制来实现的,从而导致了管理、应用复杂,且成本高.针对这一问题,提出了基于LDAP和R ad ius的统一资源访问控制机制,可以对不同的资源、不同的应用及使用者进行统一的管理.同时作者结合实际开发,提出了一个基于开放源代码系统的、可行的、稳定的认证平台及其所涉及的相关技术及方案,具有很强的实践性.
基金Project(60772088) supported by the National Natural Science Foundation of China
文摘A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) in a cluster, which is revealed by formulating resource allocation as a network utility maximization problem. Then, by maximizing the total network utility with constrains of minimizing collision probability, the optimal value of CW (Wopt) can be computed according to the number of sensor nodes. The new backoff algorithm uses the common optimal value Wopt and leads to fewer collisions than binary exponential backoff algorithm. The simulation results show that the proposed algorithm outperforms standard 802.11 DCF and S-MAC in average collision times, packet delay, total energy consumption, and system throughput.
