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--- exploring_lora [2018/09/29 23:03] – [4.2. Coverage] samer
+++ exploring_lora [2018/09/30 10:28] – [3.1. Modifying the Radio Parameters] samer
@@ Line 71: / Line 71: @@
 Take a look at the source code in ''rf95_client.ino'' and ''rf95_server.ino''. Particularly, the ''setup'' function configures the radio parameters of your LoRa devices:
-  * Central frequency (freq)
+  * Central frequency
-  * Spreading Factor (SF)
+  * Spreading Factor
-  * Bandwidth (Bw)
+  * Bandwidth
-  * Coding Rate (CR)
+  * Coding Rate
-  * Transmit power (Pow)
+  * Transmit power
 <code c++>
@@ Line 145: / Line 145: @@
 ==== -. [Classroom activity] Collisions and Packet Delivery Ratio ====
-In this section, you will measure the impact of collisions on the network throughput using different transmission periods.
+In this section, you will measure the impact of the packet arrival rate on the collision rate and consequently the PDR.
 The setting for this experiment is unique:
@@ Line 151: / Line 151: @@
   * Only one server is required in the classroom. This server should compute the ratio of successfully delivered packets or PDR.
   * All groups are required to use the same frequency, spreading factor, and coding rate.
+  * On each client, packets will be generated following a Poisson process with the same average arrival rate for all groups.
 <WRAP center round help 100%>
-  * Draw the PER as a function of the transmission period. Analyze your results.
+  * Draw the PDR as a function of the average arrival rate. Analyze your results.
-  * What type of mathematical models enables to theoretically compute the PER?
+  * What type of mathematical model enables to theoretically compute the PDR? Verify the obtained results.
 </WRAP>
 ===== -. Coverage Challenge =====
-In this section, you will study the properties of the radio channel as used by the LoRa technology. For this, you should obtain a large set of RSSI values for different distances, preferably in a free space setting.
+In this section, you are required to establish a record of LoRa coverage. You can certainly unleash your scientific imagination, but some rules must be followed to validate the record:
+  * Direct transmission between the two devices is only considered.
+  * 3D distance is computed between devices.
+  * PDR must be higher than 10% as computed for 100 packets.
 <WRAP center round help 100%>
-  * Provide the expression of the link budget.
+  * Compute the Fresnel zone for your transmission.
-  * Draw the RSSI values as a function of the distance.
+  * Provide the expression of the link budget and compute the received power using two different pathloss models.
-  * What is the path loss exponent?
+  * Compare the received power obtained experimentally with the theoretical results.
-  * Using regressions, compute a value of the path loss exponent. Analyze the result.
+  * Write an article (blog, wiki, ...) to describe your experiment.
-  * Compare the obtained sensitivity with the theoretical results computed in the previous section.
 </WRAP>
-In order to compute distances in your experiment, you can get the GPS coordinates as recorded by your smartphone using an application such as [[https://play.google.com/store/apps/details?id=com.flashlight.lite.gps.logger&hl=en|Ultra GPS Logger]]. You can export the time-location correspondence in a CSV format from this application. As for the time-RSSI correspondence, you can use a {{ :log-windows.py.zip |logger file}} on your laptop. Finally, the time matching enables you to obtain the RSSI for each GPS location, hence for different distances.
 ===== -. Grading =====