全毫米波异构网络混合回程及缓存协助内容传递方案

Hybrid backhaul and cache assisted content delivery scheme in full millimeter wave heterogeneous networks

针对部分流行多媒体文件重复下载产生的额外流量消耗引起的网络阻塞问题,提出了一种混合自回程及缓存(hybrid self-backhaul and cache, HSBC)协助的内容传递方案。在同信道和全毫米波部署的异构网络中,基于配置因子η,部分小基站(small base station, SBS)配备缓存并按照流行度等级存储多媒体内容,而无缓存配备的SBS通过多天线宏基站的自回程为用户提供请求内容,毫米波技术的引入有效缓解了网络频谱稀缺问题。利用实际天线阵列方向图模型,研究了系统的覆盖概率、平均面积吞吐量和平均延迟。结果表明,HSBC协助系统相较传统自回程(traditional self-backhaul, TSB)协助系统获得的性能增益很大程度上取决于系统参数。据此,提出了一种自适应TSB-HSBC-SBS协助内容传递模型。当缓存SBS的当前比率因子小于阈值时,选择TSB-SBS协助模型;否则使用HSBC-SBS协助模型。

To reduce the network congestion caused by the extra traffic due to repeated downloads of some popular multimedia files,a hybrid self-backhaul and cache(HSBC)assisted content delivery scheme is proposed.In a co-channel and full millimeter wave deployed heterogeneous network,with a ratio factorη,some small base stations(SBSs)are equipped with cache storing multimedia content according to a popularity level,whereas the rest of SBSs without cache provide the requested content for user terminals with the self-backhaul assistance from the macro base station equipped with multiple antenna array.The introduction of millimeter wave technology effectively alleviated the shortage of network spectrum.Based on the realistic direction pattern of multiple antenna systems,the average coverage probability,average area throughput,and average delay of the system are studied comprehensively.The results show that the performance gain of the HSBC assisted system over the traditional self-backhaul(TSB)assisted system depends largely on the system parameters.Thereby,an adaptive TSB-HSBC-SBS assisted model is proposed for content delivery.When the current ratio factor of SBS caches is less than the threshold,the TSB-SBS assisted model is selected.otherwise,the HSBC-SBS assisted model is used.