命名数据网络中面向移动用户的内容预取方法*

针对命名数据网络(Named Data Networking, NDN)移动性增强支持不足的问题，基于城区移动场景提出了一种基于移动预测的内容预取方法(Mobility-aware Prediction Approach for Content Prefetching, MAP-CP)及扩展方案(extended MAP-CP, eMAP-CP)。MAP-CP和eMAP-CP通过预测移动用户的下一接入点(Access Point, AP)，预取在当前AP下因切换AP不能获取到的Data并缓存到所预测的下一AP相关联的NDN节点中，为切换AP后的移动用户就近服务，达到降低内容获取延迟和提高响应率的目的。eMAP-CP在MAP-CP的基础上，可预取切换AP过程中请求的Data，能够进一步提高性能。基于ndnSIM的仿真实验表明，和NDN本身相比，MAP-CP和eMAP-CP具有更低的平均内容获取延迟和更高的响应率，而且eMAP-CP更优。在移动速度为20m/s，发包速率为200pps时，MAP-CP和eMAP-CP的平均内容获取延迟可分别降低约4.0%和38.7%，响应率可分别提高约1.2%和4.9%。

A content prefetching approach of mobility consumers in named data networking*

To solve the problem about supporting mobility enhancing in Named Data Network (NDN), this paper proposed a new mobility-aware prediction approach for content prefetching (MAP-CP) and an extended approach (extended MAP-CP, eMAP-CP) of mobile consumers in NDN for the city section mobility scenario. MAP-CP and eMAP-CP predicted the future access point (AP), then pre-fetched the data that could not be received under the current AP because of the handover process and cached them in the NDN node associated with the future AP predicted, to provide nearby service for the mobile consumers after the handover process, aiming to reduce the average latency from the Interest packet issued to the requested Data packet received and improve the ratio of the number of Data packets received on the total number of Interest packets issued. Based MAP-CP, eMAP-CP could improve performance further by pre-fetching the data requested during the handover process. The simulation experiment based on ndnSIM shows that MAP-CP and eMAP-CP have lower average latency and the higher ratio than original NDN, and eMAP-CP is better than MAP-CP. When the speed is 20 meters per second and the traffic is 200 packets per second, the average latency in MAP-CP and eMAP-CP can be reduced by 4.0% and 38.7% respectively, and the ratio can be increased by 1.2% and 4.9% respectively.