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標題: 3GPP中的先佔式通道碼配置演算法之研究
Channelization code allocation with preemption for 3GPP
作者: 吳志炫
Wu, Zhi-Xuan Jason
Contributors: 陳文賢
Wen-Shyen E.Chen
關鍵字: Channel Code Allocation;Preemption;IMT-2000;3GPP
日期: 2000
Issue Date: 2012-09-11 09:18:49 (UTC+8)
Publisher: 資訊科學研究所
摘要: IMT-2000 使用 DS-CDMA 技術,每個 UE (User Equipment) 都使用不同且彼此之間具有正交性 (orthogonality) 的通道碼 (channelization code)。在 3GPP 所提議的規格書中,channelization code 的產生是使用 OVSF (Orthogonal Variable Spreading Factor) 的code tree 架構。因為 OVSF code tree 在配置 channel code 時的一些限制,使得系統資源的使用效率並不理想。因此在使用 OVSF 的技術上,有效率的配置 channel code 與系統資源的管理是一個重要的議題。
3GPP 的規格書中通道碼的配置並沒有提出先佔式 (preemption) 的觀念。當 UTRAN系統沒有足夠的資源可以滿足 UE 所提出的頻寬需求時,這個新的頻寬需求將被拒絕或阻斷 (blocking)。
Algorithm LR 與 algorithm EFT [12]是一個 competitive 的演算法,且 competitiveness 只與單一 call 可允許的最大頻寬與系統總頻寬的比值 (δ) 相關。
在本篇論文中分別針對頻寬需求的不同狀況應用了兩種有效率的先佔式通道碼演算法:algorithm LR 與 algorithm EFT,提升 UTRAN access network 與 UE 間的使用效率,以滿足更多 UE 所提出的服務需求。本論文的觀念是以考慮提出 new call 時,應用 algorithm LR 與 algorithm EFT的觀念以決定是否該接受或拒絕這個新提出的 call。最後我們是以模擬的方式,假設持續時間已經事先知道,並針對不同的δ值驗證所提出的演算法。
關鍵字:IMT-2000、3GPP、Preemption、Channel Code Allocation、通道碼配置、先佔式。
The proposal for IMT-2000 employs DS-CDMA technology that each physical channel of the UE may use different channelization codes on the same frequency band. From the proposal of 3GPP, the channelization code is generated by OVSF the Orthogonal Variable Spreading Factor (OVSF) code tree. Due to the limitation of OVSF code assignment, the performance of the system can be improved.
Channelization code allocation proposed by the 3GPP does not support call preemption. When a new call is requested and if the UTRAN system does not have enough available bandwidth for the new call, it will be rejected or blocked; hence results in less flexibility.
Algorithms LR and EFT [12] are efficient competitive call preemption algorithms. The two algorithms depend only on the ratio (δ), which is the fraction of the maximum capacity used by a single call to the overall system capacity.
In order to improve the utilization and throughput of the system, we apply the two different preemption algorithms upon the ratioδ to deal with the new requested calls.
Our simulation results show that overall throughput can be improved with the introduced preemption when the call duration is known in advance. We validate the algorithms' competitiveness with respect to different values ofδ.
Appears in Collections:[依資料類型分類] 碩博士論文

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