wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows

Version 39 (modified by chunter, 10 years ago) (diff)

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Investigating Physical Carrier Sensing in the DCF with Multiple Traffic Flows

The purpose of the 802.11 Distributed Coordination Function (DCF) is to allow multiple flows of traffic to contend for a shared wireless medium. In this application note, we investigate how the 802.11 Reference Design behaves when subjected to multiple traffic flows. This note provides a case study on how the WLAN Experiment Framework can be used to control and analyze the performance of the 802.11 Reference Design.

Requirements

To run the code provided in this note, the following requirements must be met:

Experimental Setup

Experimental Setup

We use 4 traffic flows in our experiments:

  • Flow 1: Backlogged constant bit-rate (CBR) traffic from AP to STA_1
  • Flow 2: Backlogged CBR traffic from AP to STA_2
  • Flow 3: Backlogged CBR traffic from STA_1 to AP
  • Flow 4: Backlogged CBR traffic from STA_2 to AP

The colors in the figure above correspond to the colors used in per-flow plots below.

Experiment 1: Enabled Physical Carrier Sensing

Experiment Details

  • Packet Length: 1400 byte payloads (1428 bytes OTA with MAC header and FCS)
  • PHY Rate: 18 Mbps
  • Tx Power: -5 dBm
  • Trial Duration: 300 seconds
  • Channel 1
  • Physical Carrier Sensing Threshold: 250/1023

Results

Throughput vs. Time Throughput Histogram
Rx Power vs. Time
Rx Power vs. Time
Collisions (Zoomed) Collisions (1 second)

Experiment 2: Disabled Physical Carrier Sensing

Experiment Details

  • Packet Length: 1400 byte payloads (1428 bytes OTA with MAC header and FCS)
  • PHY Rate: 18 Mbps
  • Tx Power: -5 dBm
  • Trial Duration: 300 seconds
  • Channel 1
  • Physical Carrier Sensing Threshold: 1023/1023

Results

Throughput vs. Time Throughput Histogram
Rx Power vs. Time
Rx Power vs. Time
Collisions (Zoomed) Collisions (1 second)

Resources

Links to the data sets and experiment scripts used to perform this study will be posted shortly.

Attachments (1)

Download all attachments as: .zip