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1.10.Which of the following statements are correct for “multiplexing” ?
下列哪些對於”多工”敘述是正確的?
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| (a)Multiplexing is method usually used by a switch to transmitting multiple logical flows over a single physical link. 多工通常是交換機用來在一個實體鏈路上傳送多個邏輯資料流是的方法。 | |
| (b)In TDM (Time-Division-Multiplexing), data are transmitted in predetermined frequency. 分時多工技術將資料安排在預先規畫好的頻譜中進行傳送。 | |
| (c)In FDM (Frequency-Division-Multiplexing), data are transmitted in predetermined time slots. 分頻多工技術會將資料安排在預先規畫好的時段中進行傳送。 | |
| (d)One of the drawbacks of TDM is that a flow can use only the time slots allocated to it. 一個資料流只能使用分配好的時段進行傳送是分時多工的缺點之一。 | |
| (e)The link utilization for TDM and FDM may not good when some flows are overloaded and some are lightly loaded. 當部分資料流的負擔很重而部分資料流的負擔很輕時, 分時多工及分頻多工的鏈路使用率可能不太好。 |
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1.11.Which of the following statements are correct for “statistical multiplexing” ?
下列哪些對於”統計多工”敘述是正確的?
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| (a)Data are transmitted based on demand of each flow. 資料的傳輸是依據每個資料流的不同需求。 | |
| (b)Data are transmitted based on the arrival time of each flow. 資料的傳輸是依據每個資料流的抵達交換器的時間。 | |
| (c)The bandwidth used by different flows may be different. 不同資料流使用的頻寬可能也不同。 | |
| (d)The statistical multiplexing is fair due to the bandwidth used by different flows are the same. 統計多工技術是公平的, 因為每個資料流所使用的頻寬是相同的。 | |
| (e)It provides better link utilization than TDM (Time-Division-Multiplexing) and FDM (Frequency-Division-Multiplexing). 統計多工的鏈結使用率比分時多工與分頻多工更好。 |
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1.12.Which of the following scheduling policies are usually used in “statistical multiplexing” to select flows for transmitting ?
”統計多工” 通常使用下列哪些排程原則來選擇要傳輸的資料流 ?
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| (a)分時多工法 | |
| (b)Round-Rabin 循環法 | |
| (c)Priority-based (based on flow priority) 優先權法(資料流的優先權) | |
| (d)FIFO (first-in-first-out) 先進先出法 | |
| (e)FDM 分頻多工法 |