Changes between Version 60 and Version 61 of 802.11/wlan_exp/app_notes/dcf_with_multiple_flows

Timestamp:

Apr 22, 2014, 3:43:40 PM (10 years ago)

Author:

chunter

Comment:

--

802.11/wlan_exp/app_notes/dcf_with_multiple_flows

@@ -72 +72 @@
 ||  '''Physical Carrier Sensing Enabled'''  ||  '''Physical Carrier Sensing Disabled'''  ||
 
-These plots clearly demonstrate the low-mobility, mid-to-high SNR propagation environment for our experiments. And, as expected, the physical carrier sensing threshold does not impact Rx power. 
+These plots clearly demonstrate the low-mobility, mid-to-high SNR propagation environment for our experiments. And, as expected, the physical carrier sensing threshold has no substantial impact on Rx power. 
 
 ----
@@ -81 +81 @@
 ||||=  '''Throughput vs. Time  Per Flow'''  =||
 ||  [[Image(wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows/figs:cs_xput_vs_time.png, width=500)]]  ||  [[Image(wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows/figs:no_cs_xput_vs_time.png, width=500)]]  ||
-||  '''Physical Carrier Sensing Enabled'''  ||  '''PhysicalCarrier Sensing Disabled'''  ||
+||  '''Physical Carrier Sensing Enabled'''  ||  '''Physical Carrier Sensing Disabled'''  ||
 
 These plots show the throughput of each flow as a function of time. Each throughput curve is computed as a 1 second rolling window of bytes received by each node for each flow. This 1 second window is rolled over the full 300 second log in steps of 1 msec. This calculation is based on the [wiki:802.11/wlan_exp/examples/txrx_log_analysis#LogProcessThroughputvsTime log throughput analysis] example script.
@@ -132 +132 @@
 ||  [[Image(wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows/figs:cs_coll_flow_4.png, width=300)]]  || [[Image(wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows/figs:no_cs_coll_flow_4.png, width=300)]]  ||
 
+As you can see from the plots above, when physical carrier sensing is enabled, the only collisions we see are when the time offset between the nodes is essentially zero (i.e. both transmissions were started in the same slot).  However,  when carrier sensing is disabled, we can see that not only were there more collisions, we have collisions with varying time offsets meaning that the nodes failed to sense the collision.
 
 = Resources =