Performance evaluation of WiFi networks

1. UW ns-3 Wi-Fi activities
Tom Henderson
Presentation to NS3W group
December 15, 2020

2. History
> Started ns-3 project in 2005, with INRIA and Georgia
Tech.
> Helped to define the initial ns-3 802.11abg Wi-Fi model,
ported from the YANS simulator
– Mathieu Lacage and Thomas R. Henderson. 2006. Yet another
network simulator (YANS). In Proceeding from the 2006
workshop on ns-2: the IP network simulator (WNS2 '06).
Association for Computing Machinery, New York, NY, USA,
> University of Washington ns-3 Consortium provides
financial and steering committee support for the open
source project
– https://www.nsnam.org/consortium/

3. Areas of interest at UW
Past/ongoing topics
> LTE LAA/Wi-Fi coexistence
> Link-to-system mapping
> Improved PHY abstractions
> Bianchi validation
> 11ax/11be model development
Future topics
> Wi-Fi scalability
> Testbed alignment?

4. LAA Wi-Fi Coexistence project
> To support coexistence studies on an openly available
platform, Wi-Fi Alliance funded a joint University of
Washington/CTTC project to extend ns-3
> Methodology defined in 3GPP Technical Report
TR36.889
– L. Giupponi, T. Henderson, B. Bojovic and M. Miozzo. Simulating
LTE and Wi-Fi Coexistence in Unlicensed Spectrum with ns-3.
https://arxiv.org/abs/1604.06826. Jul. 2016.
– Published code: https://www.nsnam.org/wiki/LAA-WiFi-
Coexistence
> Analytical work is ongoing (S. Roy, M. Ghosh, Y. Gao,
and others)

5. Recent coexistence publications
> M. Mehrnoush, V. Sathya, S. Roy and M. Ghosh, "Analytical
Modeling of Wi-Fi and LTE-LAA Coexistence: Throughput and
Impact of Energy Detection Threshold," in IEEE/ACM Transactions
on Networking, vol. 26, no. 4, pp. 1990-2003, Aug. 2018, doi:
10.1109/TNET.2018.2856901.
> M. Mehrnoush, S. Roy, V. Sathya and M. Ghosh, "On the Fairness
of Wi-Fi and LTE-LAA Coexistence," in IEEE Transactions on
Cognitive Communications and Networking, vol. 4, no. 4, pp. 735-
748, Dec. 2018, doi: 10.1109/TCCN.2018.2867032.
> Y. Gao and S. Roy, “Achieving Proportional Fairness for LTE-LAA
and WiFi Coexistence in Unlicensed Spectrum,” IEEE Trans.
Wireless Commn., 2020.

6. Link-to-system mapping
> Following (and extending) IEEE TGn/ac methodology,
develop packet error rate models based on link
simulations
> Collaboration with Mathworks
> Being transitioned to ns-3-dev mainline code

7. Link-to-system mapping publications
> H. Safavi-Naeini, F. Nadeem and S. Roy, “Investigation and
Improvements to OFDM Wi-Fi Physical Layer Abstraction in ns-3,”
Workshop on ns-3, Seattle, Jun. 2016
> R. Patidar, S. Roy, T. Henderson and A. Chandramohan. Link-to-
System Mapping for ns-3 Wi- Fi OFDM Error Models. (Best Paper
Award) In Proceedings of the 9th Workshop on ns-3, WNS3’17,
New York, NY, USA, 2017. ACM.
> W. Jiang, S. Roy and C. McGuire. Efficient Link-to-System
Mappings for MU-MIMO Channel D Scenarios in 802.11ac WLANs.
In Proceedings of the 11th Workshop on ns-3, WNS3 ’19, New York,
NY, USA, 2019. ACM.
> Sian Jin, Sumit Roy, Weihua Jiang, and Thomas R. Henderson.
2020. Efficient Abstractions for Implementing TGn Channel and
OFDM-MIMO Links in ns-3. In Proceedings of the 2020 Workshop
on ns-3 (WNS3 2020). Association for Computing Machinery, New
York, NY, USA, 33–40.

8. Improved PHY abstractions
> Addressed the lack of multi-stage reception models
– Was no support for frame capture effect
– Did not explicitly model preamble success/failure and header
decoding
– Extended to support 11ax spatial reuse scenarios
> Collaboration with Leonardo Lanante (visiting faculty)
– L. Lanante, S. Roy, S.E. Carpenter and S. Deronne. Improved
Abstraction for Clear Channel Assessment in ns-3 802.11 WLAN
Model. In Proceedings of the 11th Workshop on ns-3, WNS3 ’19,
New York, NY, USA, 2019. ACM.

9. Bianchi validation
> As part of PHY abstraction work, validated ns-3
802.11a/n models against a Bianchi analytical model for
saturation
– https://depts.washington.edu/funlab/wp-
content/uploads/2015/03/ns3-TR.pdf
> Ongoing work with S. Roy, S. Deronne, and H. Yin
(validating across all standards, and other variations)

10. 11ax/11be model development
> Cisco and Intel have been funding development of 11ax
and 11be models since 2017-18 timeframe
– S. Carpenter, S. Deronne, and S. Avallone have been creating
the implementations
– 11ax is in the process of migration to the ns-3 mainline

11. Future directions: NSF CRI award
> Three year award to address wireless scalability in ns-3
(with Georgia Tech.)
– Continued work on PHY abstractions (link-to-system mapping)
– Parallel wireless simulations
– Event clipping
– Interference abstractions

12. Alignment with emerging NSF wireless
testbeds
> Align ns-3 models and workflows with PAWR
equivalents, to allow users to migrate more easily
between two environments
Distill experimental traces
into ns-3 trace-based models
Testbed
user may
conduct some
testbed expts.
Runs on a
single machine
or partitioned
across a cluster
provide similar
software/documentation
support to allow user to more
easily instantiate ns-3-based
experiments related to PAWR
ns-3
Figure source: Christos Siaterlis et al., On the Use of
Emulab Testbeds for Scientifically Rigorous Experiments