學位論文

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    使用前序樹有效率的辨識已註冊的RFIDs
    (2007) 黃勝宏; Sheng-Hung Huang
    以往，每件商品都需一件一件的朝讀取機掃描。現在，我們為了節省大量的掃描時間，想要在一次掃描時間內辨識出所有的商品，這就是我們所採用的RFID無線射頻技術。 為了達到以上的目的，所要保證的一項重點就是不能有商品的辨識遺漏，滿足了這個條件，接下來的要求是增快辨識速率，以目前捷運悠遊卡為例，讀取一張卡片所需的時間為0.4秒，如果商品移動速度快就可能發生有商品遺漏的情況，因此要降低辨識所需時間。 我們所採用的Protocol是由EPC所以訂製的900MHz Class 0標準，此標準所採取的防止辨識遺漏的方式為binary tree方法。這個方法必須對每一個商品皆須完整讀取其條碼才能做出辨識。 在不影響其標準架構下，我們修改其演算方法，以達到我們所要加快辨識速率的目的，我們將原先的binary tree改進為prefix-tree。首先我們將所需的辨識的條碼註冊於我們所建造的prefix-tree，接著這些條碼需要被辨識時，便在我們所事先建造的prefix-tree做辨識。我們的作法不需完整讀取其條碼即能做出辨識，其效能顯而易見的可比較出。
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    Streaming with Real Bitrates and Solving Bandwidth Competition on Bottleneck in DASH
    (2016) 王明宇; Wang, Ming-Yu
    HTTP adaptive streaming is increasingly popular in multimedia delivery nowadays. The nature of HTTP provides easy deployment to content provider and chunk-based delivery enables dynamic adaption of video quality to varying network bandwidth. In this paper, we address two topics in HTTP adaptive streaming. First is the impact of bitrate disparity. In the previous work, it shows that the advertised bitrates by manifest file and the actual bitrates are significantly different. The result of inaccurate estimation causes buffer oscillations or even buffer underrun because clients frequently select higher bitrates than the network bandwidth. To employ the extensibility feature of DASH syntax, we present a systematic method for selecting the segment which real bitrate is the closest one to the given estimated throughput. The second topic is the well-known bandwidth competition on the bottleneck. We adopt logistic function to estimate bandwidth while using it to detect occurrences of bandwidth oscillations due to competition. We propose an algorithm written on client side to stabilize the requested bitrates in competition interval. The experiments show that our solutions stabilize client behavior in competition state and streaming with real bitrates improves buffer oscillations.