Interference of Simulated IEEE 802.11 Links with Directional - - PowerPoint PPT Presentation

Interference of Simulated IEEE 802.11 Links with Directional Antennas

Michael Rademacher, Karl Jonas

first.last@h-brs.de

Hochschule Bonn-Rhein-Sieg

March 30, 2017, IEEE Wireless Days, Porto, Portugal

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Table of Content

Introduction Network Architecture Related Work Methodology Results Conclusion and Future Work

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A Different Technology for Broadband in Rural Areas

Commercial

• ff-the-shelf

(COTS) WiFi/802.11 transmitter and directional antennas ...

◮ Inexpensive (low CAPEX) ◮ Free-to-use band (low OPEX) ◮ Low energy consumption (low OPEX) ◮ Well developed and documented

... used in a controlled Multi-Radio Multi-Channel Wireless Mesh Network (WMN)1

◮ Our main research fields:

• Channel Allocation [1]
• MAC-layer optimization [2–4]
• Propagation modeling [5, 6]
• Wireless-SDN [7]

1WiFi-based Long Distance networks (WiLD) [8] or Coordinated Wireless Backhaul Network (WBN) [9].

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WiLD Architecture and Motivation

Example of a WiLD Rhein-Sieg testbed ◮ The nodes imply a static placement (vs. MANET) ◮ The nodes are equipped with multiple mesh-radios (vs. SR/DR-WMN) ◮ ≈ 3000 of these networks in the US [10]. Vendors: Ubiquity, Cambium or Mimosa [11–13].

Motivation: Multiple self-interference effects despite high gain antennas in our long-distance testbed.

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Related Work: Three Types of Interference

a) b) c) 1 2 2 3 1 1 E

Different types of interference a) Intra-flow b) Inter-flow c) External Interference [14].

2 3 1

Cone (3D) / pie-slice (2D) model of interference. A transmission from 0 to 1 does not interfere with a transmission from 2 to 3. Widely used [15–18]. ◮ Based on testbed observations, this model seems idealistic [19]. ◮ Interference measurement in the testbed are challenging -> Simulation

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Methodology - ns-3 Simulation

◮ Based on a recent ns-3 module

called SpectrumWiFiPhy [20]

Selected NS-3 parameters

Parameter Choice Standard 802.11n Freq./Width 5180/20 MHz MAC-Layer AdhocWifiMac Station Manager ConstantRate Data Rate MCS7 Control Rate MCS3 A-MPDU-Size 8192 Bytes RTS/CTS Disabled TxPower 5 dBm Simulation Time 30 s Traffic UDP, saturated Distance 1 km Payload Size 1450 Bytes Routing IPv4 Static Delay Model ConstantSpeed Error-Rate Model Nist Propagation Model Friis MAC-Layer timings Depended

◮ New ’File-Antenna’ model: (a) Antenna diagram data-sheet based on .ant file (b) Verification of the antenna diagram with ns-3

Antenna: Ubiquity PowerBridge M5

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Methodology - Setup

◮ All antennas are perfectly aligned. Same channel everywhere. ◮ Trace signals directly before the radio (SpectrumWiFiPhy module) ◮ Energy Detection Threshold (EDT):

◮ A signal < EDT = noise. Carrier sensing reports idle medium.

◮ Notation for interference: source-node → interference-node.

Intra-Flow

◮ α = 0...180◦ ◮ n0 → n2. n0 to n1 interferes at n2. ◮ n0 → n3. n0 to n1 interferes at n3.

Inter-Flow

◮ ∆y = 5...1250 m ◮ n1 → n3. n1 to n0 interferes at n3. ◮ n1 → n2. n1 to n0 interferes at n2.

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Results - Intra-Flow - One Stream

20 40 60 80 100 120 140 160 180 Angle, α[°] 10 20 30 40 50 Throughput [Mbps] −110 −96 −82 −68 −54 −40 Signal [dBm] 20 40 60 80 100 120 140 160 180 Angle, α[°] 10 20 30 40 50 Throughput [Mbps] n0 ⇒ n3 n0 → n2 n0 → n3

UDP: n0 ⇒ n3 via n1 and n2 ! n0 → n2, n0 → n3: wave form according to the side-lobes of the antenna. ! Fluctuating throughput. 1 At α ≈ 11◦: ◮ n0 → n3 > EDT: n3 is vulnerable to the transmission from n0. ◮ n0 → n2 < EDT: n2 is not able to detect a transmission from n0 to n1. ◮ n0 and n2 are const.

• transm. Interference at n3.

2 At α ≈ 21◦: ◮ n0 → n2, n0 → n3 < EDT. ◮ No interference

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Results - Intra-Flow - Two Streams

20 40 60 80 100 120 140 160 180 Angle, α[°] 10 20 30 40 50 Throughput [Mbps] −110 −96 −82 −68 −54 −40 Signal [dBm] 20 40 60 80 100 120 140 160 180 Angle, α[°] 10 20 30 40 50 Throughput [Mbps] n0 ⇒ n3 n3 ⇒ n0 n0 → n2 n0 → n3

Two UDP streams: n0 ⇒ n3 and n3 ⇒ n0 ◮ Similar results compared to the one stream case. Including the interesting angles α ≈ 11◦ and α ≈ 21◦.

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Results - Inter-Flow - Same Direction

200 400 600 800 1000 1200 ∆ y [m] 10 20 30 40 50 Throughput [Mbps] −110 −96 −82 −68 −54 −40 Signal [dBm] 12 24 36 48 60 Average Backoff [Slots] 200 400 600 800 1000 1200 ∆ y [m] 10 20 30 40 50 Throughput [Mbps] n1 ⇒ n0 n3 ⇒ n2 n1 → n3 n1 → n2

• avg. Backoff

Two UDP streams, n1 ⇒ n0 and n3 ⇒ n2 (same direction). ◮ n1 → n3 decreases, n1 → n2 wave form 1 At ∆y ≈ 180 m ◮ n1 → n3 > EDT ◮ n1 → n2 < EDT ◮ If n3 & n1 choose the same backoff slot there is no collision at n0 & n2. 2 At ∆y ≈ 385−405 m or ∆y ≈ 570−690 m: ◮ n1 → n3, n1 → n2 < EDT 3 At ∆y ≈ 405−575 m or ∆y ≈ 690−940 m: ◮ n1 → n3 < EDT ◮ n1 → n2 > EDT ◮ avg. backoff slots at n1/n3 increase

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Results - Inter-Flow - Different direction

200 400 600 800 1000 1200 ∆ y [m] 10 20 30 40 50 Throughput [Mbps] −110 −96 −82 −68 −54 −40 Signal [dBm] 12 24 36 48 60 Average Backoff [Slots] 200 400 600 800 1000 1200 ∆ y [m] 10 20 30 40 50 Throughput [Mbps] n1 ⇒ n0 n2 ⇒ n3 n1 → n3 n1 → n2

• avg. Backoff

Two UDP streams, n1 ⇒ n0 and n2 ⇒ n3 (different direction). ◮ The DCF works for all distances: Average Backoff. 1 At ∆y ≈ 180 m ◮ n1 → n3 > EDT ◮ n1 → n2 < EDT ◮ Remarkable difference: One flow dominates the other. Further analysis is needed.

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Conclusion and Future Work

Done: Results for interference of (simple) WiFi links with directional antennas Load real-world antenna diagrams in ns-3 ! Side-lobes of antennas have a significant impact on interference

◮ The widely used cone model would lead to significantly different results

not reflecting real-world build-ups.

◮ Source code, logs, and high-quality images free available online2

Current work and next steps:

◮ Load larger topologies based on Google-Earth .kmz format ◮ Calculate propagation based on satellite data (incl. hills) ◮ Evaluate different Channel Allocation algorithms for WiLD

2http://mc-lab.inf.h-brs.de/wild.xml

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Thank you very much!

Are there any questions?

www.h-brs.de M.Sc. Michael Rademacher Fachbereich Informatik Grantham-Allee 20 53757 Sankt Augustin

• Tel. +49 2241 865 151

Fax +49 2241 865 8151 michael.rademacher@h-brs.de

Acknowledgment: This work has been funded by the Federal Ministry of Education and Research of the Federal Republic of Germany (Foerderkennzeichen 16KIS0332).

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References and Acronyms I

[1]

• M. Rademacher et al. “Towards Centralized Spectrum Allocation Optimization for Multi-Channel Wireless Backhauls”. In:

e-Infrastructure e-Services Dev. Ctries. Ed. by J. Nungu, Amos and Pehrson, Bjorn and Sansa-Otim. Springer International Publishing, 2015, pp. 74–83. [2]

• M. Rademacher, M. Kretschmer, and K. Jonas. “Exploiting IEEE802.11n MIMO Technology for Cost-Effective Broadband

Back-Hauling”. In: 5th Int. IEEE EAI Conf. on e-Infrastructure and eServices for Developing Countries. 2013. [3]

• M. Rademacher.

Performance estimation and optimization of the IEEE802.11 MAC layer for long distance point-to-point links. Tech. rep. Hochschule Bonn-Rhein-Sieg, 2015, p. 109. [4]

• M. Rademacher, M. Chauchet, and K. Jonas. “A Token-Based MAC For Long-Distance IEEE802.11 Point-To-Point

Links”. In: VDE ITG-Fachbericht Mobilkommunikation (2016). [5]

• M. Rademacher and M. Kessel. “An Empirical Evaluation of the Received Signal Strength Indicator for fixed outdoor

802.11 links”. In: VDE ITG-Fachbericht Mobilkommunikation 20 (2015), pp. 62–66. [6]

• M. Rademacher et al. “Experimental Results For the Propagation of Outdoor IEEE802.11 Links”. In:

VDE ITG-Fachbericht Mobilkommunikation 22 (2016). [7]

• M. Rademacher et al. “Experiments with OpenFlow and IEEE802.11 Point-to-Point Links in a WMN”. In:

ICWMC - Twelfth Int. Conf. Wirel. Mob. Commun. IARIA, 2016, pp. 99–105. isbn: 978-1-61208-514-2. [8]

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[9]

• C. Mannweiler. “Context-Enabled Optimization of Energy-Autarkic Networks for Carrier-Grade Wireless Backhauling”.

PhD thesis. TU Kaiserslautern, 2015, p. 259. 14

References and Acronyms II

[10] Interisle Consulting Group. The Essential Role of Fixed Wireless in Universal Broadband Coverage. 2015. [11] Ubiquiti Networks, Inc. 2016. url: https://www.ubnt.com/broadband/technology/ (visited on 07/25/2016). [12] Mimosa Networks, Inc. 2016. url: https://www.mimosa.co/technology/ (visited on 07/25/2016). [13] Cambium Networks, LTD. 2016. url: http://www.cambiumnetworks.com/resources/type/white-paper/ (visited on 07/25/2016). [14]

• F. Shzu-Juraschek. “Distributed channel assignment for multi-radio wireless mesh networks”. PhD Thesis. Humboldt

University of Berlin, 2014. [15]

• S. M. Das et al. “DMesh: Incorporating practical directional antennas in multichannel wireless mesh networks”. In:

IEEE J. Sel. Areas Commun. 24.11 (2006), pp. 2028–2039. issn: 07338716. doi: 10.1109/JSAC.2006.881631. [16]

• N. Sadeghianpour, T. C. Chuah, and S. W. Tan. “Joint channel assignment and routing in multiradio multichannel

wireless mesh networks with directional antennas”. In: Int. Journal of Commun. Systems 28.9 (2015), pp. 1521–1536. issn: 10745351. doi: 10.1002/dac.2731. [17]

• W. Zhou, X. Chen, and D. Qiao. “Practical Routing and Channel Assignment Scheme for Mesh Networks with Directional

Antennas”. In: IEEE Int. Conf. on Commun. IEEE, 2008, pp. 3181–3187. isbn: 978-1-4244-2075-9. doi: 10.1109/ICC.2008.599. [18]

• Q. Liu, X. Jia, and Y. Zhou. “Topology control for multi-channel multi-radio wireless mesh networks using directional

antennas”. In: Wireless Networks 17.1 (2011), pp. 41–51. issn: 1022-0038. doi: 10.1007/s11276-010-0263-1. [19]

• M. Rademacher and K. Jonas. “Interference of Simulated IEEE 802.11 Links with Directional Antennas”. In:

IEEE Wireless Days. IEEE, 2017. 15

References and Acronyms III

[20]

• L. Giupponi et al. Simulating LTE and Wi-Fi Coexistence in Unlicensed Spectrum with ns-3. 2016. url:

http://arxiv.org/abs/1604.06826.

WBN Coordinated Wireless Backhaul Network WiLD WiFi-based Long Distance networks

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