隨著MU-MIMO的技術發展日益蓬勃，在資料數量不超過接收天線數量的限制底下，AP可以允許同時與多個使用者傳輸，有效的增進傳輸效能。在WLANs中上傳的情況下，若有多個使用者都想要與AP傳輸資料，選擇哪些使用者同時傳輸將會大大影響傳輸效能，因為這些使用者是同時並使用同頻率與AP溝通，彼此會造成一定程度的干擾，我們設計了一個以競爭為基礎的傳輸機制，能夠兼顧傳輸效能與公平性，讓AP選擇對傳輸效能最有利的一群使用者來做傳輸。
為了公平性的考量，我們對傳統MAC protocol中RTS/CTS的機制做了一點修改，同時維持了以競爭為基礎的精神。而在傳輸效能的考量上，由於AP掌握了所有使用者的通道資訊，哪些使用者有傳輸資格將由AP來抉擇。模擬結果顯示，藉著這樣的傳輸機制，我們的方法能確實的提升傳輸效能並且保有一定的公平性。

The advent of multi-user multiple input multiple output (MU-MIMO) technology enables an access point (AP) to simultaneously communicate with multiple stations. Considering the fact that typically an AP has more antennas than a station has, uplink MU-MIMO, which allows multiple stations to concurrently send data to the AP in the uplink direction, can improve network performance. To maximize the total throughput, we consider the IEEE 802.11 family and design a contention-based protocol by taking transmission rate and fairness into consideration. In our protocol, the AP will choose a group of transmit antennas which can produce the maximum throughput. The simulation results indicate that our proposed mechanism improves total throughput and achieves fairness to some extent.

Abstract iv
中文摘要 vi
Table of Contents vii
List of Figures ix
Chapter 1 Introduction 1
1.1. Concept of MIMO 1
1.2. SNR Projection 3
Chapter 2 Related Work 7
2.1. Uplink Medium Access Protocol 7
2.2. User and Transmit Antenna Selection 8
2.3. Rate Adaptation 9
Chapter 3 Channel Model 10
Chapter 4 Protocol Description 12
4.1. Preliminary 12
4.2. Fairness and Starvation Issues 14
Chapter 5 Antenna Selection Strategy 17
5.1. Antenna Selection 17
5.1.1. Gram–Schmidt Process 19
5.1.2. Combine with The Protocol 20
Chapter 6 Simulation Results 22
6.1. Simulation Setup 23
6.2. Numerical Results 25
Chapter 7 Conclusion 32
Bibliography 33

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