Browse

Improving MIMO Performance in Wi-Fi Networks by using Collision Resolution and User Selection

DC Field Value Language
dc.contributor.advisor김종권-
dc.contributor.author이규행-
dc.date.accessioned2017-07-13T07:09:25Z-
dc.date.available2017-07-13T07:09:25Z-
dc.date.issued2015-08-
dc.identifier.other000000028739-
dc.identifier.urihttps://hdl.handle.net/10371/119089-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 김종권.-
dc.description.abstractMultiple-Input Multiple-Output (MIMO) technologies have emerged as a key component to increase the capacity of wireless networks. The MIMO scheme either simultaneously transmits to multiple users at a time or focuses energy towards a single user to enhance the data rate. A number of Wi-Fi standards based on MIMO technology have been developed, and recently, several commercial products have been successfully deployed on the market. Unfortunately, many commercial MIMO-based Wi-Fi products fail to fully exploit the advantages of the MIMO technology, even though the MIMO technology could play a key role in improving the wireless network performance. MIMO nodes cannot provide their higher data rates, especially when they coexist with SISO nodes. Meanwhile, in Wi-Fi networks, significant Channel State Information (CSI) feedback overhead has been obstacle to the performance of MU-MIMO transmission and user selection. Most of these problems are observed to root in the inefficient PHY and MAC design of current MIMO based Wi-Fi systems: the MAC simply abstracts the advancement of PHY technologies as a change of data rate. Hence, the benefit of new PHY technologies are either not fully exploited, or they even may harm the performance of existing network protocols.
In this dissertation we introduce three co-designs of PHY/MAC layers for MIMO based Wi-Fi networks, in order to overcome the intrinsic limitations of the current MIMO based Wi-Fi network and improve the network capacity. First, we show the Interference Alignment and Cancelation (IAC) based collision resolution scheme for heterogeneous MIMO based Wi-Fi systems. Second, we present a practical user selection scheme for MU-MIMO Wi-Fi networks. Finally, we improve the proposed user selection scheme by exploiting a frequency domain signaling scheme and using a capacity gain as a selection metric. We have validated the feasibility and performance of our designs using extensive analysis, simulation and USRP testbed implementation.
-
dc.description.tableofcontentsABSTRACT i
CONTENTS iii
LIST OF FIGURES vi
LIST OF TABLES ix
CHAPTER I: Introduction 1
1.1 Background and Motivation 1
1.2 Goal and Contribution 8
1.3 Thesis Organization 9
CHAPTER II: MIMO based Collision Resolution 10
2.1 Introduction 10
2.2 Related Work 12
2.3 Background 14
2.3.1 Packet Collision Problems in MIMO Networks 14
2.3.2 IAC 15
2.4 802.11mc 17
2.4.1 Protocol Overview 17
2.4.2 Packet Collision Resolution via IAC 19
2.4.3 Collisions between Multiple CTSs 22
2.4.4 Optimal p 23
2.4.5 Discussion 28
2.5 USRP Experiments 33
2.5.1 Micro Benchmark 33
2.5.2 Macro Benchmark 39
2.6 NS-2 Simulations 43
2.6.1 Setting 43
2.6.2 Packet Loss Rate due to Collision 44
2.6.3 CWMin 45
2.6.4 Data Size 46
2.6.5 Number of Node Pairs (N) 49
2.6.6 Proportion of MIMO Receivers (q_2) 50
2.6.7 Postamble Probability (p) 52
2.6.8 Performance in Dynamic Network Configurations 54
2.7 Conclusion 55
CHAPTER III: User Selection for MU-MIMO Transmission 56
3.1 Introduction 56
3.2 Related Work 58
3.3 Background 60
3.3.1 System Model 60
3.3.2 User Selection 61
3.4 802.11ac+ 62
3.4.1 Overview 62
3.4.2 Channel Hint Broadcasting 63
3.4.3 Active CSI Feedback 66
3.5 Fair Scheduling 72
3.5.1 RR-11ac+ 72
3.5.2 PF-11ac+ 73
3.5.3 Summary 73
3.6 Performance Evaluation 75
3.6.1 Setting 75
3.6.2 802.11ac+ Performance 76
3.6.3 Fair Scheduling Protocol Performance 79
3.7 Conclusion 82
CHAPTER IV: Distributed Frequency Domain User Selection 83
4.1 Introduction 83
4.2 Motivation 84
4.3 DiFuse 88
4.3.1 Protocol Overview 88
4.3.2 Distributed Feedback Contention 89
4.3.3 Slot Threshold Design 95
4.3.4 Proportional Fair Selection 97
4.3.5 Discussions 98
4.4 Performance Evaluation 101
4.4.1 Micro Benchmark 101
4.4.2 System-Level Performance 105
4.5 Conclusion 113
CHAPTER V: Conclusion 114
BIBLIOGRAPHY 115
초 록 122
-
dc.formatapplication/pdf-
dc.format.extent5509770 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectMU-MIMO-
dc.subjectMAC-
dc.subjectCollision-
dc.subjectChannel State Information-
dc.subjectUser Selection-
dc.subject.ddc621-
dc.titleImproving MIMO Performance in Wi-Fi Networks by using Collision Resolution and User Selection-
dc.typeThesis-
dc.description.degreeDoctor-
dc.citation.pages123-
dc.contributor.affiliation공과대학 전기·컴퓨터공학부-
dc.date.awarded2015-08-
Appears in Collections:
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Electrical and Computer Engineering (전기·정보공학부)Theses (Ph.D. / Sc.D._전기·정보공학부)
Files in This Item:
  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse