多細胞合作式傳輸排程

在蜂巢式系統中，當頻率複用等於一時，來自其他細胞的干擾而使得系統效率下降的現象將會十分顯著，因此，我們將無法像傳統的單細胞系統一樣忽略來自其他細胞的干擾，特別是處在細胞邊緣的使用者們。多點合作式傳送是長期演進技術進化版系統中處理來自其他細胞干擾的候選技術之一。而合作是排程是多點合作是傳送的方案之一，在這個方案中，基地台們可以透過後端傳輸傳送信另和排程資訊，且不需要傳送資料資訊。在這篇論文中，我們在多細胞多輸出多出入的下行系統中提出合作式排程演算法，且在我們的演算法中，基地台間不需要為了排程而透過後端傳輸交換排程資訊。在本文中，我們著重受不同細胞的干擾最嚴重的細胞邊緣用戶，並且將排程演算法結合實體層演算法，在考慮細胞間干擾下，提高系統性能。一般來說，通道近乎正交的用戶較適合在同一時間做排程並傳送。由於多輸入多輸出的通道設置，我們所提出的排程演算法考慮多輸入多輸出通道間的角度距離度量的弦距離。在模擬中，我們在兩種不同的天線設置下，比較我們提出的演算法和幾個現有的排程方法。兩種天線設置分別是，接收天線的數量大於用戶接收到的數據流，和接收天線的數量等於用戶收到的數據流。前者有額外的自由度，但後者沒有。當接收端天線有額外的自由度去抑制干擾時，只需使用通道振幅導向的排程方法即可。但是，當接收端沒有額外的自由度時，除了通道振幅以外，我們發現必須要排程演算法裡進一步考慮弦距離。

關鍵字

多細胞；多用戶多輸入多輸出；多點合作式傳送；合作式排程；弦距離；細胞間干擾

並列摘要

In cellular system, the unavoidable inter-cell interference would dramatically degrade the system throughput when frequency reuse of one is considered, and then we can't ignore them anymore as traditional single cell,especially for cell-edge users. Coordinated multi-point (CoMP) transmission/reception is one of candidate techniques in LTE-Advanced (LTE-A) system to solve this problem and improve throughput. And Coordinated scheduling (CS) is one kind of schemes in CoMP. In this scheme, backhauls across BSs can transmit signaling and scheduling information. It means that BSs don’t have to transmit data across backhaul anymore in CS. Here, we propose coordinated scheduling algorithms under the multi-cell multi-input multi-output (MIMO) downlink system, and there are no additional backhaul between coordinated cells required for scheduling. In this thesis, we focus on cell-edge users, and then the user scheduling are designed by combining with the physical algorithms to improve performance with the consideration of inter-cell interference. In general, users whose channels are nearly orthogonal are suitable to be scheduled at the same time. Due to MIMO channel setting, our proposed scheduling employs the chordal distance as the distance metric between MIMO channels, which could serve as the angle between two channels. In the simulation, we compare with several existing scheduling strategies under two antenna settings, which one is that the number of receiver antenna is larger than the received data streams of a user, and the other is that the number of receiver antenna is equal to thereceived data streams. The former has additional degree of freedom, but the latter does not have. When receiver has additional degree of freedom to suppress interference, we could only adopt the proposed norm-oriented scheduling strategy. When the receiver does not have the additional degree of freedom, the scheduling needs to further consider the chordal distance in addition to channel norm.

並列關鍵字

Multi-cell ； Multi-user multi-input multi-output ； CoMP ； Coordinated Scheduling ； Chordal distance ； Inter-cell interference

參考文獻

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國際替代計量

多細胞合作式傳輸排程

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