Changes between Version 4 and Version 5 of 802.11/wlan_exp/app_notes/ibss_multiple_flows

Timestamp:

Oct 1, 2014, 2:21:32 PM (10 years ago)

Author:

chunter

Comment:

--

802.11/wlan_exp/app_notes/ibss_multiple_flows

@@ -5 +5 @@
 The standard AP/STA flavors of 802.11 have a fundamental limitation: The AP is capable of transmitting to any of its association stations, but the STA devices can ''only'' directly transmit to the AP. STA devices cannot directly communicate with other STA devices on the BSS without first hopping through the AP.
 
-IBSS devices are different. The "Independent Basic Service Set" allows for any device to communicate to any other device, allowing for more general mesh configurations. Unlike the [wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows Investigating Physical Carrier Sensing in the DCF with Multiple Traffic Flows] application note, we are not limited to a total of 4 possible flows when using IBSS nodes. In this application note, we extend the network to a total of 6 flows while still only using 3 nodes.
+IBSS devices are different. The "Independent Basic Service Set" allows for any device to communicate to any other device, allowing for more general mesh configurations. Unlike the [wiki:802.11/wlan_exp/app_notes/dcf_with_multiple_flows Investigating Physical Carrier Sensing in the DCF with Multiple Traffic Flows] application note, we are not limited to a total of 4 possible flows. In this application note, we extend the network to a total of 6 flows while still only using 3 IBSS nodes.
 
 == Experiment Details ==
@@ -23 +23 @@
 
 [[Image(topology.png,width=600)]]
+
+
+= Tx/Rx Log Results =
+
+The 802.11 Reference Design experiments framework includes a [wiki:802.11/wlan_exp/log flexible logging system] that runs in real-time at every node. This system keeps a record of every Tx and Rx event at the node. For Tx events the log includes both the high-level MPDU Tx (as implemented in CPU High) and the low-level PHY Tx events for each MPDU. Each low-level Tx record includes the timestamp of the actual PHY transmission plus MAC parameters for the transmission (number of backoff slots, current contention window, re-transmission count, etc.). By retrieving the logs from every node following the experiment and analyzing them together, we can gain significant understanding of the behaviors of the nodes and how various parameters impact performance on short and long timescales.
+
+||=  '''Throughput vs. Time'''  =||=  '''Throughput Histogram'''  =||
+||  [[Image(xput_vs_time.png, width=500)]]  ||  [[Image(xput_hist.png, width=500)]]  ||
+
+The above figures show 300 seconds of data from the experiment. In the first figure, the black line shows the total sum throughput that was sustained in the network. The ~12.5Mbps that was achieved is just slightly below the [wiki:802.11/Benchmarks/Throughput#Throughputvs.PayloadLength theoretical max] throughput that can be achieved at the 14Mbps PHY rate. The slight reduction is due to the overhead of the DCF along with unavoidable collisions among the 6 traffic flows.