Packet-level network simulators such as ns-3 require accurate physical (PHY) layer models for packet error rate (PER) for wideband transmission over fading wireless channels. To manage complexity and achieve practical runtimes, suitable link-to-system mappings can convert high fidelity PHY layer models for use by packet-level simulators. This work reports on two new contributions to the ns-3 Wi-Fi module, which presently only contains error models for Single Input Single Output (SISO), additive white Gaussian noise (AWGN) channels. To improve this, a complete implementation of a link-to-system mapping technique for IEEE 802.11 TGn fading channels is presented that involves a method for efficient generation of channel realizations within ns-3. The runtimes for the prior method suffers from scalability issues with increasing dimensionality of Multiple Input Multiple Output (MIMO) systems. We next propose a novel method to directly characterize the probability distribution of the"effective SNR" in link-to-system mapping. This approach is shown to require modest storage and not only reduces ns-3 runtime, it is also insensitive to growth of MIMO dimensionality. We describe the principles of this new method and provide details about its implementation, performance, and validation in ns-3.
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Verification of ns-3 Wi-Fi Rate Adaptation Models on AWGN Channels
The performance of Wi-Fi networks depends on the ability of devices to adapt their transmissions to dynamic channel/network conditions. Hence, “Rate Adaptation Algorithms (RAAs)” have been devised to allow nodes to select appropriate modulation and coding schemes (and other parameters) in response to varying channel/network conditions. These algorithms are neither standardized nor typically divulged by vendors, and devising a ‘performance-optimal’ RAA for specific scenario remains an active topic that necessitates a complex, multi-parameter cross-layer (PHY/MAC) approach. The ns-3 network simulator offers detailed models of the Wi-Fi medium access control (MAC) layer, including three reference RAA implementations; however testing and validation of these RAA models has been very limited to date. This paper reports on initial test and validation for ns-3 RAA models via 802.11n/ac/ax simulations. After describing the RAA scope and implementations, we explore and summarize insights from test results as to a) whether the ns-3 RAAs are able to achieve the correct rates as configuration is varied and b) how they respond to step changes in the received signal-to-noise ratio (SNR) as a means for exploring their convergence properties.
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- Award ID(s):
- 2016379
- PAR ID:
- 10466274
- Editor(s):
- Henderson, Thomas; Imputato, Pasquale; Liu, Yuchen; Gamess, Eric
- Date Published:
- Journal Name:
- WNS3 '23: Proceedings of the 2023 Workshop on ns-3
- Page Range / eLocation ID:
- 109 to 114
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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