Wi-Fi: 802.11 WLAN
Overview:
Users can design, model and simulate WiFi networks using devices such as Access Points (AP), Wireless Nodes (STA). A drag & drop GUI enables users to quickly create the network and set properties with a simple right click. The results of a simulation run are presented in a unified dashboard for convenient analysis. Graphics plots comprises of application throughputs, link throughputs, buffer occupancy and TCP congestion windows. The tabular presentation includes end-to-end delays, jitter, errors, packets generated / received / collided, route tables, TCP Acks, retransmissions etc.
WLAN Protocol Capabilities
MAC Layer:
- Rate Adaptation – Minstrel, Generic
- CSMA/CA - protocol with RTS / CTS exchange, DIFS, Backoff and collisions, SIFS and ACK
- Infrastructure - BSS mode and DCF mode
- MPDU aggregation in 802.11n and 802.11ac
- IEEE802.11e – Quality of Service based on EDCA
PHY Layer:
| Standard | Frequency | Bandwidth | Modulation | Data Rate |
|---|---|---|---|---|
| 802.11a | 5 GHz | 20MHz | OFDM | 54 Mbps |
| 802.11b | 2.4 GHz | 20MHz | DSSS | 11 Mbps |
| 802.11g | 2.4 GHz | 20MHz | OFDM | 54 Mbps |
| 802.11n (MIMO 4x4) | 2.4 and 5 GHz | 20 and 40MHz | HT | 600 Mbps |
| 802.11ac (MIMO 8x8) | 5 GHz | 20, 40, 80 and 160MHz | VHT | 6.933 Gbps |
| 802.11p | 5.9 GHz | 5, 10, 20MHz | OFDM | 54 Mbps |
| 802.11ax | Under Development | |||
SNR / BER / PER Calculation
- Received Signal strength (RSS) is calculated as transmit power less RF propagation losses. The propagation losses include pathloss, fading and shadowing.
- Interference is calculated by considering all co-channel transmissions occurring at the same time. Propagation models are again used to compute the powers of all interfering signals from all interfering transmitters.
- With the RSS and interference, we calculate the SINR
- The BER is then computed by looking up the SINR-BER curves for the given MCS.
- The packet error probability (PEP) is calculated from the BER
With the rate and PEP, we have an abstraction through which packets can be transmitted and received over the air. These computations are done for each packet since the channel can be time-varying. All radio parameters can be logged in a CSV file for each packet transmission.
Propagation Models:
Application 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
- HTTP
- Peer to Peer
- CBR
- Application encryption using AES, DES, XOR and TEA algorithms
Source Code: Protocol Source C code with DLL interfacing for simulation in the loop debugging.
Simulation Results
Results Dashboard
- 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
Packet Animation
- Animates packet flow over wired and wireless links, as well as node movement
- Colour 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.
WLAN Traffic - Wireshark Packet Capture
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
Unsupported features/limitations
- Association, probing, beaconing
- MSDU aggregation
- Directional Antennas
- Beamforming
- PLCP preamble reception