73 research outputs found
Final report on the evaluation of RRM/CRRM algorithms
Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin
๋น๋ฉดํ๋์ญ ์ ๋ฃฐ๋ผ ํต์ ์ ์ฑ๋ฅ ๋ถ์ ๋ฐ ์ฑ๋ฅ ํฅ์ ๊ธฐ๋ฒ ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ) -- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ์ ๊ธฐยท์ ๋ณด๊ณตํ๋ถ, 2021. 2. ๋ฐ์ธ์
.3GPP๋ LAA (licensed-assisted access)๋ผ๊ณ ํ๋ 5GHz ๋น๋ฉดํ ๋์ญ
LTE๋ฅผ ๊ฐ๋ฐํ์ต๋๋ค. LAA๋ ์ถฉ๋ ๋ฐฉ์ง ๊ธฐ๋ฅ์ ์ฌ์ฉํ๊ธฐ ์ํด Wi-Fi์ CSMA /
CA (Carrier Sense Multiple Access with Collision avoidance)์ ์ ์ฌํ LBT (Listen
Before Talk) ์์
์ ์ฑํํ์ฌ ๊ฐ LAA ๋ค์ด ๋งํฌ ๋ฒ์คํธ์ ํ๋ ์ ๊ตฌ์กฐ ์ค๋ฒ ํค๋๋
๊ฐ๊ฐ์ ์ข
๋ฃ ์๊ฐ์ ๋ฐ๋ผ ๋ฌ๋ผ์ง๋๋ค. ์ด์ LBT ์์
. ์ด ๋
ผ๋ฌธ์์๋ ๋น๋ฉดํ ๋์ญ
์
๋ฃฐ๋ฌ ํต์ ์ ๋ถ์ํ๊ธฐ์ํ ์์น ๋ชจ๋ธ์ ์ ์ํ๋ค. ๋ค์์ผ๋ก, ๋น๋ฉดํ ๋์ญ ์
๋ฃฐ๋ฌ
ํต์ ์ ๋ค์ ๋ ๊ฐ์ง ํฅ์๋ ๊ธฐ๋ฅ์ ๊ณ ๋ คํฉ๋๋ค. ๋์ญ ๋
๋ฆฝํ ์
๋ฃฐ๋ฌ ํต์ . ๊ธฐ์กด WiFi ๋ถ์ ๋ชจ๋ธ๋ก๋ LAA์ ์ฑ๋ฅ์ ํ๊ฐํ ์ ์๋ค๋ ์ ์ ๊ฐ์ํ์ฌ ๋ณธ ์์ ์์๋
์ฌ๋ฌ ๊ฒฝํฉ ์งํ ๋ NodeB๋ก ๊ตฌ์ฑ๋ LAA ๋คํธ์ํฌ์ ์ฑ๋ฅ์ ๋ถ์ํ๊ธฐ์ํ ์๋ก์ด
Markov ์ฒด์ธ ๊ธฐ๋ฐ ๋ถ์ ๋ชจ๋ธ์ ์ ์ํฉ๋๋ค. LAA ํ๋ ์ ๊ตฌ์กฐ ์ค๋ฒ ํค๋์ ๋ณํ.
LTE-LAA๋ LTE์์ ์์ ๋ ์๋ ์ ์ ์๊ณ ๋ฆฌ์ฆ์ ์ํด ์ ์ ๋ณ์กฐ ๋ฐ ์ฝ๋ฉ (AMC)
์ ์ฑํํฉ๋๋ค. AMC๋ ์งํ ๋ nodeB (eNB)๊ฐ ํ์ฌ ์ ์ก์ ์ฑ๋ ํ์ง ํ์๊ธฐ ํผ๋
๋ฐฑ์ ์ฌ์ฉํ์ฌ ๋ค์ ์ ์ก์์ํ ๋ณ์กฐ ๋ฐ ์ฝ๋ฉ ๋ฐฉ์ (MCS)์ ์ ํํ๋๋ก ๋์ต๋๋ค.
๋ผ์ด์ ์ค ๋์ญ์์ ๋์ํ๋ ๊ธฐ์กด LTE์ ๊ฒฝ์ฐ ๋
ธ๋ ๊ฒฝํฉ ๋ฌธ์ ๊ฐ ์์ผ๋ฉฐ AMC ์ฑ๋ฅ
์ ๋ํ ์ฐ๊ตฌ๊ฐ ์ ์งํ๋๊ณ ์์ต๋๋ค. ๊ทธ๋ฌ๋ ๋น๋ฉดํ ๋์ญ์์ ๋์ํ๋ LTE-LAA
์ ๊ฒฝ์ฐ ์ถฉ๋ ๋ฌธ์ ๋ก ์ธํด AMC ์ฑ๋ฅ์ด ์ ๋๋ก ์ฒ๋ฆฌ๋์ง ์์์ต๋๋ค. ์ด ํธ์ง์์๋
AMC ์ด์์ ๊ณ ๋ คํ ํ์ค์ ์ธ ์ฑ๋ ๋ชจ๋ธ์์ LTELAA ์ฑ๋ฅ์ ๋ถ์ํ๊ธฐ์ํ ์๋ก
์ด Markov ์ฒด์ธ ๊ธฐ๋ฐ ๋ถ์ ๋ชจ๋ธ์ ์ ์ํฉ๋๋ค. ๋ฌด์ ๋คํธ์ํฌ ๋ถ์์ ๋๋ฆฌ ์ฌ์ฉ๋๋
Rayleigh ํ์ด๋ฉ ์ฑ๋ ๋ชจ๋ธ์ ์ฑํํ๊ณ ๋ถ์ ๊ฒฐ๊ณผ๋ฅผ ns-3 ์๋ฎฌ๋ ์ดํฐ์์ ์ป์ ๊ฒฐ๊ณผ
์ ๋น๊ตํฉ๋๋ค. ๋น๊ต ๊ฒฐ๊ณผ๋ ํ๊ท ์ ํ๋๊ฐ 99.5%๋ก ๋ถ์ ๋ชจ๋ธ์ ์ ํ๋๋ฅผ ๋ณด์ฌ์ค๋๋ค. ๋์ ๋ฐ์ดํฐ ์๋์ ๋ํ ์๊ตฌ ์ฌํญ์ผ๋ก ์ธํด 3GPP๋ LTE-LAA๋ฅผ์ํ ๋ค์ค
๋ฐ์กํ ์ด์์ ์ ๊ณตํ์ต๋๋ค. ๊ทธ๋ฌ๋ ๋ค์ค ๋ฐ์กํ ๋์์ OOBE์ ์ทจ์ฝํ๊ณ ์ ํ๋
์ ์ก ์ ๋ ฅ์ ์ฌ์ฉํ์ฌ ๋นํจ์จ์ ์ธ ์ฑ๋ ์ฌ์ฉ์ ์ด๋ํฉ๋๋ค. ๋ณธ ๋
ผ๋ฌธ์ ์ฑ๋ ํจ์จ์
๋์ด๊ธฐ์ํ ์๋ก์ด ๋ค์ค ๋ฐ์กํ ์ ๊ทผ ๋ฐฉ์์ ์ ์ํ๋ค. ์ฐ๋ฆฌ๊ฐ ์ ์ํ ๋ฐฉ์์ ์ ์ก
๋ฒ์คํธ๋ฅผ ์ฌ๋ฌ ๊ฐ๋ก ๋ถํ ํ๊ณ ์ ์ก ์ ๋ ฅ ์ ํ์ ์ถฉ์กฑํ๋ฉด์ ์งง์ ์๋ธ ํ๋ ์ ์ ์ก
์ ์ฌ์ฉํฉ๋๋ค. ๋ํ ์ฑ๋ ์ํ๋ฅผ ์ ํํ๊ฒ ํ๋จํ์ฌ OOBE ๋ฌธ์ ๋ฅผ ๊ทน๋ณต ํ ์์๋
์๋์ง ๊ฐ์ง ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํฉ๋๋ค. ์ํํธ์จ์ด ์ ์ ๋ผ๋์ค๋ฅผ ์ฌ์ฉํ๋ ํ๋กํ
ํ์
์ 99% ์ด์์ ์ ํ๋๋ก ์ฑ๋ ์ํ๋ฅผ ๊ฒฐ์ ํ๋ ์๋์ง ๊ฐ์ง ์๊ณ ๋ฆฌ์ฆ์ ์คํ
๊ฐ๋ฅ์ฑ๊ณผ ์ฑ๋ฅ์ ๋ณด์ฌ์ค๋๋ค. ns-3 ์๋ฎฌ๋ ์ด์
์ ํตํด ์ ์ ๋ ๋ค์ค ๋ฐ์กํ ์ก์ธ์ค
๋ฐฉ์์ด ๊ธฐ์กด LBT ์ ํ A ๋ฐ ์ ํ B์ ๋นํด ์ฌ์ฉ์์ธ์ง ์ฒ๋ฆฌ๋์์ ๊ฐ๊ฐ ์ต๋ 59%
๋ฐ 21.5%์ ์ฑ๋ฅ ํฅ์์ ๋ฌ์ฑ ํจ์ ํ์ธํ์ต๋๋ค. ๋ ๊ฑฐ์ LAA์๋ ๋ฐฐํฌ ๋ฌธ์ ๊ฐ
์๊ธฐ ๋๋ฌธ์ 3GPP์ MulteFire ์ผ๋ผ์ด์ธ์ค๋ ๋น๋ฉดํ ๋์ญ ๋
๋ฆฝํ ์
๋ฃฐ๋ฌ ํต์ ์์ค
ํ
์ ์ ์ํ์ต๋๋ค. ๊ทธ๋ฌ๋, ์ข
๋์ ๋น๋ฉดํ ๋์ญ ๋
๋ฆฝํ ์
๋ฃฐ๋ฌ ํต์ ์์คํ
์ ์ํฅ
๋งํฌ ์ ์ด ๋ฉ์์ง์ ์ ์ก ํ๋ฅ ์ด ๋ฎ๋ค. ์ด ๋
ผ๋ฌธ์ Wi-Fi ๋ธ๋ก ACK ํ๋ ์์ ์
๋งํฌ
์ ์ด ๋ฉ์์ง๋ฅผ ๋ฃ๋ W ARQ : Wi-Fi ์ง์ HARQ๋ฅผ ์ ์ํฉ๋๋ค. ๋ํ W-ARQ์ ์ฒ
๋ฆฌ ์ฑ๋ฅ์ ํฅ์์ํค๊ธฐ ์ํด ๋ณ๋ ฌ HARQ ๋ฐ ํด๋ฌ์คํฐ๋ง ๋ Minstrel์ ์ ์ํฉ๋๋ค.
์ฐ๋ฆฌ๊ฐ ์ ์ํ ์๊ณ ๋ฆฌ์ฆ์ ๊ธฐ์กด MulteFire๊ฐ ๊ฑฐ์ ์ ๋ก ์ฒ๋ฆฌ๋ ์ฑ๋ฅ์ ๋ณด์ด๋ ๊ฒฝ์ฐ
๋์ ์ฒ๋ฆฌ๋ ์ฑ๋ฅ์ ๋ณด์ฌ์ค๋๋ค. ์์ฝํ๋ฉด ๋น๋ฉดํ ๋์ญ ์
๋ฃฐ๋ฌ ํต์ ์ ์ฑ๋ฅ์ ๋ถ์
ํฉ๋๋ค. ์ ์ ๋ ๋ชจ๋ธ์ ์ฌ์ฉํจ์ผ๋ก์จ ์ฐ๋ฆฌ๋ ๋ ๊ฑฐ์ ๋ค์ค ๋ฐ์กํ ๋์์ ์ฃผ์ฅํ๋ฉฐ
๋น๋ฉดํ ์
๋ฃฐ๋ฌ ํต์ ์ HARQ๋ ํจ์จ์ ์ด์ง ์๋ค. ์ด๋ฌํ ์ด์ ๋ก, ์ฐ๋ฆฌ๋ ์ต์ฒจ๋จ ๊ธฐ
์ ์ ๋นํด UPT ๋ฐ ์ฒ๋ฆฌ๋๊ณผ ๊ฐ์ ๋คํธ์ํฌ ์ฑ๋ฅ ํฅ์์ ๋ฌ์ฑํ๋ OOBE ์ธ์ ์ถ๊ฐ
์ก์ธ์ค ๋ฐ W-ARQ๋ฅผ ์ ์ํฉ๋๋ค.3GPP has developed 5 GHz unlicensed band LTE, referred to as licensed-assisted
access (LAA). LAA adopts listen before talk (LBT) operation, resembling Wi-Fis
carrier sense multiple access with collision avoidance (CSMA/CA), to enable collision
avoidance capability, while the frame structure overhead of each LAA downlink burst
varies with the ending time of each preceding LBT operation.
In this dissertation, we propose numerical model to analyze unlicensed band cellular communication. Next, we consider the following two enhancements of unlicensed band cellular communication: (i) out-of-band emission (OOBE) aware additional carrier access, and (ii) Wi-Fi assisted hybrid automatic repeat request (H-ARQ)
for unlicensed-band stand-alone cellular communication.
Given that, existing analytic models of Wi-Fi cannot be used to evaluate the performance of LAA, in this letter, we propose a novel Markov chain-based analytic model
to analyze the performance of LAA network composed of multiple contending evolved
NodeBs by considering the variation of the LAA frame structure overhead. LTE-LAA
adopts adaptive modulation and coding (AMC) for the rate adaptation algorithm inherited from LTE. AMC helps the evolved nodeB (eNB) to select a modulation and
coding scheme (MCS) for the next transmission using the channel quality indicator
feedback of the current transmission. For the conventional LTE operating in the licensed band, there is no node contention problem and AMC performance has been
well studied. However, in the case of LTE-LAA operating in the unlicensed band,
AMC performance has not been properly addressed due to the collision problem. In
this letter, we propose a novel Markov chain-based analysis model for analyzing LTELAA performance under a realistic channel model considering AMC operation. We
adopt Rayleigh fading channel model widely used in wireless network analysis, and
compare our analysis results with the results obtained from ns-3 simulator. Comparison results show an average accuracy of 99.5%, which demonstrates the accuracy of
our analysis model.
Due to the requirement for a high data rate, the 3GPP has provided multi-carrier
operation for LTE-LAA. However, multi-carrier operation is susceptible to OOBE and
uses limited transmission power, resulting in inefficient channel usage. This paper proposes a novel multi-carrier access scheme to enhance channel efficiency. Our proposed
scheme divides a transmission burst into multiple ones and uses short subframe transmission while meeting the transmission power limitation. In addition, we propose an
energy detection algorithm to overcome the OOBE problem by deciding the channel status accurately. Our prototype using software-defined radio shows the feasibility
and performance of the energy detection algorithm that determines the channel status with over 99% accuracy. Through ns-3 simulation, we confirm that the proposed
multi-carrier access scheme achieves up to 59% and 21.5% performance gain in userperceived throughput compared with the conventional LBT type A and type B, respectively.
Since the legacy LAA has deployment problem, 3GPP and MulteFire alliance proposed unlicensed band stand-alone cellular communication system. However, conventional unlicensed band stand-alone cellular communication system has low transmission probability of uplink control messages. This disertation proposes W-ARQ: Wi-Fi
assisted HARQ which put uplink control messages into Wi-Fi block ACK frame. In
addition we propose parallel HARQ and clustered Minstrel to enhance throughput
performance of W-ARQ. Our proposed algorithm shows high throughput performance
where conventional MulteFire shows almost zero throughput performance.
In summary, we analyze the performance of unlicensed-band cellular communication. By using the proposed model, we insist the legacy multi-carrier operation and HARQ of unlicensed cellular communication is not efficient. By this reason, we propose
OOBE aware additional access and W-ARQ which achievee enhancements of network performance such as UPT and throughput compared with state-of-the-art techniques.Abstract i
Contents iv
List of Tables vii
List of Figures viii
1 Introduction 1
1.1 Unlicensed Band Communication System . . . . . . . . . . . . . . . 1
1.2 Overview of Existing Approaches . . . . . . . . . . . . . . . . . . . 2
1.2.1 License-assisted access . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 Further LAA . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.3 Non-3GPP Unlicensed Band Cellular Communication . . . . 6
1.3 Main Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.1 Performance Analysis of LTE-LAA . . . . . . . . . . . . . . 6
1.3.2 Out-of-Band Emission Aware Additional Carrier Access for
LTE-LAA Network . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.3 W-ARQ: Wi-Fi Assisted HARQ for Unlicensed Band StandAlone Cellular Communication System . . . . . . . . . . . . 8
1.4 Organization of the Dissertation . . . . . . . . . . . . . . . . . . . . 8
2 Performance Analysis of LTE-LAA network 10
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Proposed Markov-Chain Model . . . . . . . . . . . . . . . . . . . . . 14
2.3.1 Markov Property . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.2 Markov Chain Model for EPS Type Variation . . . . . . . . . 16
2.3.3 LAA Network Throughput Estimation . . . . . . . . . . . . . 18
2.4 Model Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3 Out-of-Band Emission Aware Additional Carrier Access for LTE-LAA
Network 35
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2 Related work and Background . . . . . . . . . . . . . . . . . . . . . 37
3.2.1 Related work . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2.2 Listen Before Talk . . . . . . . . . . . . . . . . . . . . . . . 38
3.2.3 Out-of-Band Emission . . . . . . . . . . . . . . . . . . . . . 39
3.3 Multi-carrier Operation of LTE-LAA . . . . . . . . . . . . . . . . . . 39
3.4 Carrier Sensing considering Out-of-Band Emission . . . . . . . . . . 47
3.4.1 Energy Detection Algorithm . . . . . . . . . . . . . . . . . . 49
3.4.2 Nominal Band Energy Detection . . . . . . . . . . . . . . . . 50
3.4.3 OOBE-Free Region Energy Detection . . . . . . . . . . . . . 51
3.5 Additional Carrier Access Scheme . . . . . . . . . . . . . . . . . . . 52
3.5.1 Basic Operation . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.5.2 Transmission Power Limitation . . . . . . . . . . . . . . . . 53
3.5.3 Dividing Transmission Burst . . . . . . . . . . . . . . . . . . 54
3.5.4 Short Subframe Decision . . . . . . . . . . . . . . . . . . . . 54
3.6 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.6.1 Performance of Energy Detection considering OOBE . . . . . 57
3.6.2 Simulation Environments . . . . . . . . . . . . . . . . . . . . 57
3.6.3 Performance of Proposed Carrier Access Scheme . . . . . . . 58
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4 W-ARQ: Wi-Fi Assisted HARQ for Unlicensed Band Stand-Alone Cellular Communication System 66
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.4 W-ARQ: Wi-Fi assisted HARQ for Unlicensed Band Stand-Alone Cellular Communication System . . . . . . . . . . . . . . . . . . . . . . 69
4.4.1 Parallel HARQ . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.4.2 Clustered Minstrel . . . . . . . . . . . . . . . . . . . . . . . 72
4.5 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5 Concluding Remarks 80
5.1 Research Contributions . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Abstract (In Korean) 90
๊ฐ์ฌ์ ๊ธ 93Docto
DESIGN AND DEVELOPMENT OF CARRIER ASSIGNMENT AND PACKET SCHEDULING IN LTE-A AND Wi-Fi
The highly competitive environment in today's wireless and cellular network industries is making the management of systems seek for better and more advance techniques to keep masses of data, complexity of systems and deadline constrains under control with a lower cost and higher efficiency. Therefore, the management is getting significant attentions by researchers in order to increase the efficiency of the resource usage to provide high quality services. Two of the cornerstones of the management system in wireless and cellular network are carrier assignment and packet scheduling. Therefore, this work focuses on analysis and development of carrier assignment and packet scheduling methods in multi-band Wi-Fi and LTE-A networks. First, several existing carrier assignment methods which are developed by considering different strategists in LTE and LTE-A are analyzed. Secondly, a new technique for the carrier assignment methods for LTE and LTE-A is developed to improve the efficiency of carrier assignment methods. Thirdly, a novel carrier assignment method is proposed by considering the behaviors of mobile users for LTE and LTE-A. Then, a novel architecture with packet scheduling scheme is proposed for next generation mobile routers in multi-band Wi-Fi environment as similar to LTE-A. Finally, the scheme is improved based on energy awareness. Results show that the developed methods improve the performance of the systems in comparison to existing methods. The proposed methods and related analysis should help network engineers and service providers build next generation carrier assignment and packet scheduling methods to satisfy users in LTE, LTE-A and Wi-Fi
EVEREST IST - 2002 - 00185 : D23 : final report
Deliverable pรบblic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version
A comprehensive simulation analysis of LTE Discontinuous Reception (DRX)
In an LTE cell, Discontinuous Reception (DRX) allows
the central base station to configure User Equipments for
periodic wake/sleep cycles, so as to save energy. DRX operations
depend on several parameters, which can be tuned to achieve optimal
performance with different traffic profiles (i.e., CBR vs.
bursty, periodic vs. sporadic, etc.). This work investigates how to
configure these parameters and explores the trade-off between
power saving, on one side, and per-user QoS, on the other. Unlike
previous work, chiefly based on analytical models neglecting key
aspects of LTE, our evaluation is carried out via simulation. We
use a fully-fledged packet simulator, which includes models of all
the protocol stack, the applications and the relevant QoS metrics,
and employ factorial analysis to assess the impact of the many
simulation factors in a statistically rigorous way. This allows us
to analyze a wider spectrum of scenarios, assessing the interplay
of the LTE mechanisms and DRX, and to derive configuration
guidelines
Contention techniques for opportunistic communication in wireless mesh networks
Auf dem Gebiet der drahtlosen Kommunikation und insbesondere auf den tieferen Netzwerkschichten sind gewaltige Fortschritte zu verzeichnen. Innovative Konzepte und Technologien auf der physikalischen Schicht (PHY) gehen dabei zeitnah in zellulรคre Netze ein. Drahtlose Maschennetzwerke (WMNs) kรถnnen mit diesem Innovationstempo nicht mithalten. Die Mehrnutzer-Kommunikation ist ein Grundpfeiler vieler angewandter PHY Technologien, die sich in WMNs nur ungenรผgend auf die etablierte Schichtenarchitektur abbilden lรคsst. Insbesondere ist das Problem des Scheduling in WMNs inhรคrent komplex. Erstaunlicherweise ist der Mehrfachzugriff mit Trรคgerprรผfung (CSMA) in WMNs asymptotisch optimal obwohl das Verfahren eine geringe Durchfรผhrungskomplexitรคt aufweist. Daher stellt sich die Frage, in welcher Weise das dem CSMA zugrunde liegende Konzept des konkurrierenden Wettbewerbs (engl. Contention) fรผr die Integration innovativer PHY Technologien verwendet werden kann. Opportunistische Kommunikation ist eine Technik, die die inhรคrenten Besonderheiten des drahtlosen Kanals ausnutzt. In der vorliegenden Dissertation werden CSMA-basierte Protokolle fรผr die opportunistische Kommunikation in WMNs entwickelt und evaluiert. Es werden dabei opportunistisches Routing (OR) im zustandslosen Kanal und opportunistisches Scheduling (OS) im zustandsbehafteten Kanal betrachtet. Ziel ist es, den Durchsatz von elastischen Paketflรผssen gerecht zu maximieren. Es werden Modelle fรผr รberlastkontrolle, Routing und konkurrenzbasierte opportunistische Kommunikation vorgestellt. Am Beispiel von IEEE 802.11 wird illustriert, wie der schichtรผbergreifende Entwurf in einem Netzwerksimulator prototypisch implementiert werden kann. Auf Grundlage der Evaluationsresultate kann der Schluss gezogen werden, dass die opportunistische Kommunikation konkurrenzbasiert realisierbar ist. Darรผber hinaus steigern die vorgestellten Protokolle den Durchsatz im Vergleich zu etablierten Lรถsungen wie etwa DCF, DSR, ExOR, RBAR und ETT.In the field of wireless communication, a tremendous progress can be observed especially at the lower layers. Innovative physical layer (PHY) concepts and technologies can be rapidly assimilated in cellular networks. Wireless mesh networks (WMNs), on the other hand, cannot keep up with the speed of innovation at the PHY due to their flat and decentralized architecture. Many innovative PHY technologies rely on multi-user communication, so that the established abstraction of the network stack does not work well for WMNs. The scheduling problem in WMNs is inherent complex. Surprisingly, carrier sense multiple access (CSMA) in WMNs is asymptotically utility-optimal even though it has a low computational complexity and does not involve message exchange. Hence, the question arises whether CSMA and the underlying concept of contention allows for the assimilation of advanced PHY technologies into WMNs. In this thesis, we design and evaluate contention protocols based on CSMA for opportunistic communication in WMNs. Opportunistic communication is a technique that relies on multi-user diversity in order to exploit the inherent characteristics of the wireless channel. In particular, we consider opportunistic routing (OR) and opportunistic scheduling (OS) in memoryless and slow fading channels, respectively. We present models for congestion control, routing and contention-based opportunistic communication in WMNs in order to maximize both throughput and fairness of elastic unicast traffic flows. At the instance of IEEE 802.11, we illustrate how the cross-layer algorithms can be implemented within a network simulator prototype. Our evaluation results lead to the conclusion that contention-based opportunistic communication is feasible. Furthermore, the proposed protocols increase both throughput and fairness in comparison to state-of-the-art approaches like DCF, DSR, ExOR, RBAR and ETT
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