臺灣博碩士論文加值系統

全雙工的傳收機制(Full-duplex relaying)，也就是允許同時傳送訊號跟接收訊號，被認為是在5G(5th generation mobile networks)網路環境下提供較好的服務品質跟擴展長期演進技術(Long Term Evolution, LTE)基地台範圍的關鍵技術。由於對系統流量跟高速資料率的需求逐漸上升，設計一個確保產出(throughput)跟降低電量使用的中繼(relay)選擇就是一件非常重要的事情，希望可以做到在可以接受的低耗電量下提供服務。此外，防止行動用戶(cellular user)間的訊號干擾發生跟為更多使用者預留資源也是相當重要的。然而，先前的研究最多只允許一個D2D(Device-to-Device)連結去使用一個次通道(subchannel)，造成無法提供更多使用者服務。
在本篇論文中，我們著重在基於正交頻分多址(Orthogonal Frequency Division Multiple Access ,OFDMA)及全雙工的多個D2D使用者環境下。藉由非衝突的群組發現演算法(non-conflict group discovery algorithm)，以及D2D直接發現技術(D2D direct discovery technology)，像是信標幀(beacon frame)，我們可以先將成對D2D的裝置分配至不同的群組當中。我們將在同一個群組內的D2D對視為不衝突的。藉由建立一個D2D對透過中繼在傳送訊號時消耗電量的矩陣，我們基於匈牙利演算法(Hungarian method)，提出了一個以群組為導向選擇中繼的方法，在一個由中繼輔助傳送訊號的環境下，它允許子通道的重複利用。藉由這個方法，不同的D2D對只要在相同的群組中，就可以同時使用相同的子通道進行傳輸。相對於現有的中繼選擇上來說，允許次通道重複使用的方法可以獲得較佳的產出和頻道利用率。尤其在越來越密集的網路環境下，更多的D2D對要能被基地台容納，以及頻譜的資源可以更好的為蜂窩用戶預留資源。
模擬的結果顯示出我們提出的方法在D2D對分配的群組數量較少時，相較於現存不允許次通道重複使用的中繼選擇方法，可以增進35%整體產出。

Full-duplex relaying, which allows relays to transmit and receive signals simultaneously, is a key technique to provide better quality of service and to extend coverage of LTE base station(BS) service in 5th generation mobile networks(5G) networks. Due to the increasing demands for more system capacity and higher data rate, it is essential to design a throughput-guaranteed and power-aware relay selection mechanism so that services can be successfully accomplished within tolerable power consumption. It is also imperative to prevent cellular users from interfering and preserve resources for more user at the same time. However, previous works allowed one Device-to-device (D2D) link at most to access the same subchannel, which cannot provide more user accesses.
In this thesis, we concentrate on the environment of multiple D2D user pairs under full duplex relay communications based on orthogonal frequency division multiple access (OFDMA). Using the non-conflict group discovery algorithm, we firstly divide D2D pairs into different groups based on the neighbor lists of all devices. D2D pairs in the same group are considered non-conflictive. By building a matrix which represents the power consumption of D2D transmission peers through relays, we propose a group-oriented relay selection scheme based on Hungarian method allowing subchannel reuse over relay-assisted D2D networks. Applying this mechanism, different D2D pairs are able to transmit messages at the same subchannel, whenever they are in the same group. Better throughput and spectrum usage than currently available relay selection schemes without subchannel reusing can be obtained. Particularly, more D2D pairs in high dense networks can be accommodated and spectrum resources for cellular users can be better preserved.
Simulation results show that our proposed mechanism can improve the total throughput by up to 35% as compared to an existing relay selection scheme without subchannel reusing, called as PRS-D2D, when most D2D pairs are in few groups.

摘要 i
Abstract ii
Contents iv
List of Tables vi
List of Figures vii
1. Introduction 1
1.1. Motivation 1
1.2. Thesis Contributions 1
1.3. Thesis Structure 2
2. Related Work 3
2.1. D2D communications with relay-assisted 3
2.2. Neighbor List Report 4
2.3. Data Rate of User Pair 4
2.4. Literatures 5
3. Throughput-guaranteed Relay Selection with Subchannel Reusing 7
3.1. Problem Formulation 7
3.2. Non-Conflict Group Discovery 9
3.3. Bipartite Graph Construction 11
3.4. Throughput-guaranteed Relay Selection 13
4. Performance Evaluation 16
4.1. Simulation Environment 16
4.2. Simulation Results 18
5. Conclusions 23
References 24

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