A Differential Feedback Scheme Exploiting the Temporal and Spectral Correlation

Channel state information (CSI) provided by limited feedback channel can be utilized to increase the system throughput. However, in multiple input multiple output (MIMO) systems, the signaling overhead realizing this CSI feedback can be quite large, while the capacity of the uplink feedback channel is typically limited. Hence, it is crucial to reduce the amount of feedback bits. Prior work on limited feedback compression commonly adopted the block fading channel model where only temporal or spectral correlation in wireless channel is considered. In this paper, we propose a differential feedback scheme with full use of the temporal and spectral correlations to reduce the feedback load. Then, the minimal differential feedback rate over MIMO doubly selective fading channel is investigated. Finally, the analysis is verified by simulations

Social Media Communication by Local Governments and Its Implications for Urban Planning

Social media has altered traditional communication and enriched traditional social networks. In addition to its use for personal communication and business marketing, social media has also been proved to be a valuable tool for urban planners and managers. However, there are relatively few studies about how social media communication may inform the design of urban master plans. The objectives of the thesis are to understand how the city governments have used social media to engage with the general public on urban planning issues, and assess if social media contents can be used to inform urban planning. The 10 top digital cities with mid-range population size rated by the Center for Digital Government (CDG) were selected as study sites. A combination of statistical analyses and manual topic classification were used to reveal the patterns of the social media discussion. The outputs were then compared with the comprehensive plans of these cities. The results showed that (1) social media contents encompass a broad range of planning issues, and have been used as supplemental information to improve the comprehensive plans; (2) there is no statistical difference between Facebook and Twitter discussion on planning issues percentage-wise; and (3) Overall, the comprehensive plan provides more detailed and structured visions and strategies to address planning issues compared with fragmented social media discussion. Adviser: Zhenghong Tan