Wi-Fi Modelling

Modules

  • Modelling and Simulation of Physical and MAC Layer for WLAN (2.4 GHz & 5 GHz) for IEEE 802.11n & 802.11ac.
  • MAC layer: Rate adaptation algorithms
  • Coexisting WLAN networks
  • Downlink Performance of OFDMA 802.11ax WLAN Networks in dense deployments.

Modeling and Simulation of Physical and MAC Layer for WLAN

Standards considered: 802.11n & 802.11ac at 2.4 GHz and 5 GHz

Performance metrics

–Throughput
–Latency
–Packet Error Rate
–Range

Models for various scenarios

–Scenario 1: Client at different distances from an Access Point
–Scenario 2: Client in motion WRT a single Access Point
–Scenario 3: Client in motion while covering multiple Access Points

Simulation Setup in MATLAB

Matlab_Sim

MAC layer: Rate adaptation algorithms

  • Rate adaptation is used to deal with variations in channel and interference
    • Transmitter adapts its modulation and coding scheme (MCS) to get different rates
  • A crucial algorithm that affects performance of Wi-Fi networks
  • Factors that affect throughput:
    • Dynamic nature of channel
    • Interference from other WiFi transmitters
    • Heterogeneous receiver capability
  • Goal: Maximize throughput while containing packet error rate

Comparison of DRCA, Ideal RAA, and Minstrel:

wi-fi-modelling (15)

Matlab’s Dynamic Rate Control Algorithm (DRCA):

wi-fi-modelling (2)

Ideal Rate Control Algorithm:

wi-fi-modelling (3)

Benchmarking: Ideal vs. DRCA (802.11ac):

wi-fi-modelling (4)

Minstrel-HT Rate Control Algorithm:

  • Evaluating the Matlab implementation of Minstrel-HT with a reference known as MinstrelHTWifiManager from NS3.
wi-fi-modelling (6)
  • Response of algorithm (MCS selection and MRR update) to packet failures/success given the same initialization and randomisations were matched.
wi-fi-modelling (7)

MAC layer: Rate adaptation algorithms

  • WLAN co-existence analysis inside a plane
    • Analysing throughput between interfering APs
wi-fi-modelling (8)
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  • Minstrel-HT integration with multi-node system-level simulations
wi-fi-modelling (10)
  • Simulated Rate adaptation in an increased number of WLAN networks

Downlink Performance of OFDMA 802.11ax WLAN Networks in dense deployments

  • Gain of the MU-OFDMA feature of the 802.11ax standard provide
  • 11ax vs 802.11n simulations: Implemented in Matlab
    • 11n vs. 802.11ax
    • Throughput-based scheduling for extreme fairness
wi-fi-modelling (11)
  • Scheduled access as opposed to contention-based access.
  • Different RUs for different STAs depending on channel conditions.
  • 11ax: OFDMA for MU transmissions
    • Compare per-node throughput and latency
wi-fi-modelling (12)
  • Round-robin vs. throughput-based OFDMA scheduler
wi-fi-modelling (13)
wi-fi-modelling (14)

Ongoing and future work:

  • Default round-robin scheduler in Matlab:
    • RUs allocated based on the number of previous transmissions.
    • STAs with the least number of transmissions at the start of each frame are allocated RUs.
  • Throughput-based scheduler:
    • RUs allocated based on the running value of throughput.
    • STAs with the least throughput at the start of each frame are allocated RUs.
  • Scheduled access vs. contention-based access:
    • Allocating RUs based on SINR per RU for each STA.

People

Shyam Sundar

Shyam Sundar

Nithish K Gnani

Nithish K Gnani

Other Team members: Amol Bhindwale, Rushabha Balaji, Sourav Mukherjee, Vinay U Pai