802.11-WLAN

Overview:

Users can design, model and simulate wireless networks using Access Point, Wireless Node, Router, Wired Node, Switch.
A drag & drop GUI enables users to quickly create the network and set properties with a simple right click & edit.

WLAN Protocol Capabilites

MAC Layer protocols:

  • IEEE802.11e – Quality of Service based EDCA
  • Rate Adaptation – Minstrel, Generic
  • CSMA/CA - protocol with RTS / CTS exchange
  • Infrastructure - BSS mode and DCF mode
  • MPDU aggregation in 802.11n and 802.11ac
  • MAC States: MAC_IDLE, WF_NAV, Wait_DIFS, BACKING_OFF,TXing_MPDU, Txing_BroadCast, TXing_ACK, TXing_RTS, TXing_CTS, Wait_DATA, Wait_CTS, Wait_ACK, Wait_BlockACK, OFF

PHY Layer protocols:

  • IEEE802.11a
    • Transmission Type – OFDM
    • Bandwidth – 20MHz
    • Frequency Band – 5GHz, supporting standard channels
    • Base Rate (Control Rate) – 6Mbps
    • PHY Rates - 9Mbps,12Mbps,18Mbps,24Mbps,36Mbps, 48Mbps and 54Mbps
  • IEEE802.11b
    • Transmission Type – DSSS
    • Bandwidth – 20MHz
    • Frequency Band – 2.4GHz, supporting standard channels
    • Base Rate (Control Rate) – 1Mbps
    • PHY Rates - 2 Mbps, 5.5 Mbps and 11 Mbps
  • IEEE802.11g
    • Transmission Type – OFDM
    • Bandwidth – 20MHz
    • Frequency Band – 2.4GHz, supporting standard channels
    • Base Rate (Control Rate) - 6Mbps
    • PHY Rates - 9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps and 54Mbps
  • IEEE802.11n
    • Transmission Type – HT, supports packet aggregation and MIMO with upto 4*4 transmitting and receiving antennae
    • Bandwidth – 20/40MHz
    • Frequency Bands – 2.4/5GHz, supporting standard channels
    • Base Rate (Control Rate) – 7.2Mbps
    • PHY Rates - upto 288.8Mbps for 20MHz bandwidth and 600Mbps for 40MHz bandwidth
    • Guard Interval – 400/800ns
  • IEEE802.11ac
    • Transmission Type – VHT, supports packet aggregation and MIMO with upto 8*8 transmitting and receiving antennae
    • Bandwidth – 20/40/80/160MHz
    • Frequency Band – 5GHz, supporting standard channels
    • Base Rate (Control Rate) – 7.2Mbps
    • PHY Rates - upto 346.8Mbps for 20MHz bandwidth, 800Mbps for 40MHz bandwidth, 1733.2Mbps for 80MHz bandwidth and 3466.8Mbps for 160MHz bandwidth
    • Guard Interval – 400/800ns
  • IEEE802.11p
    • Transmission Type – OFDM
    • Bandwidth – 10MHz
    • Frequency Band – 5GHz, supporting standard channels

PHY States: RX_OFF, RX_ON_IDLE, RX_ON_BUSY, TRX_ON_BUSY, SLEEP

SNR / BER / PER Calculation
Each packet received is probabilistically evaluated for successful or failed reception. The probability depends on the modulation, on the signal to noise (and interference) ratio for the packet, and on the state of the physical layer (e.g. reception is not possible while transmission is taking place);

The interference noise variable keeps tracks of all other received signals so that the correct interference power for each packet can be computed when a reception decision has to be made.

SNR is calculated (at the start and end of each packet) by using the formula below

The bit error rate (BER) is the number of bit errors divided by the total number of transferred bits during a studied time interval. The BER calculation is calculated using as SNR – BER tables for different modulation schemes.

Rx Power Calculation
Received power is calculated (at the start and end of each packet) by using the formula below

Path Loss Models:

  • Friis Free Space
  • Log Distance
  • COST231 HATA Suburban
  • COST231 HATA Urban
  • HATA Urban
  • HATA Suburban
  • Indoor Office
  • Indoor Factory
  • Indoor Home

Fading Models

  • Rayleigh,
  • Nakagami

Shadowing Models

  • Log-Normal
  • Constant

Not Supported / Limitations

  1. Association, probing, beaconing
  2. MSDU aggregation
  3. Directional Antennas
  4. Beamforming
  5. PLCP preamble reception
  6. Propagation model source codes are not open to user
  7. SNR – BER modulation tables source codes are not open to user

Source Code: Protocol Source C code with DLL interfacing for simulation in the loop debugging.

Traffic Generator

  • File Transfer Protocol (FTP)
  • Database Application
  • Voice Traffic
  • Video Traffic
  • Custom Model: Users can develop custom application model based on Packet size and inter-arrival time available in the following probability distributions
  • Email
  • HTTP
  • Peer to Peer
  • CBR
  • Application encryption using AES and DES algorithms

Background: Grid / Map

Simulation Results

Network Metrics, Link metrics Application metrics, Protocol Specific metrics for each protocol, and Forwarding tables.

Metrics include throughputs, Delays, Data & control packet information and protocol specific Results

Graphical plots over time for link and application throughputs and TCP congestion window

Detailed Packet Trace (All Components)

  • All protocols have detailed packet level trace generated in a tab ordered .txt, .xlsx format.
  • Packet trace contains the details of packet like packet number, source, destination, arrival time, payload, overheads etc.

Detailed Event Trace (All Components)

  • All protocols have detailed event level trace generated in a tab ordered .txt, .xlsx format.
  • Event trace contains the details of event like Event Time, Event Type, Device Type, Application ID etc.

Dynamic Metrics: Dynamic metrics allows users to monitor the value of a parameter over simulation time.

Command Line Interface – CLI

  • CLI mode of running for more concise and powerful means of control
  • Facilitates use of automated scripts for running batch simulations
  • Model network configurations using XML based configuration files

Packet Animation

  • Animates packet flow over wired and wireless links, as well as node movement
  • Color variation for data, control and error packets
  • Animation settings via play, pause and time-slide
  • 25+ info fields now available with packet animator.
  • Wide range of animation options including plots, battery level, graphs, tables and more.
  • Visualization with inbuilt graphs for link and application throughput.
  • Graph controls with Colouring, XY Axis settings, Grid Settings, Zoom and more.

Wireless network in NetSim:
Example screen shot showing an in-flight wi-fi system analysis

ACL Configuration:

External Interfacing:
Interfacing with Wireshark and MATLAB

Additional Resources:
YouTube videos
R & D Projects:
Knowledge base (Answers on WLAN)
Example Application: Simulation and analysis of in-flight Wifi network capacity