wikiroute

networking recipes

User Tools

Site Tools

Trace:
exploring_lora

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
Next revisionBoth sides next revision
exploring_lora [2018/10/06 14:01] – [4.1. Time on Air] samerexploring_lora [2018/10/13 09:53] – [4.1. Time on Air] samer
Line 31: Line 31:
  
 Unzip the RadioHead library and copy it to your sketchbook library folder as detailed in [[https://www.arduino.cc/en/Guide/Libraries]]. Unzip the RadioHead library and copy it to your sketchbook library folder as detailed in [[https://www.arduino.cc/en/Guide/Libraries]].
 +
 +<WRAP center round tip 75%>
 +Make sure to restart your computer after the installation of Arduino IDE and run the software as administrator.
 +</WRAP>
 +
 +
 ==== -. Installation ==== ==== -. Installation ====
  
Line 42: Line 48:
  
 <WRAP center round tip 75%> <WRAP center round tip 75%>
-For Arduino Mega 2560, additional drivers for Microsoft Windows can be installed from [[http://wch.cn/download/CH341SER_ZIP.html]].+For Arduino Mega 2560, additional drivers for Microsoft Windows 7 or 8 can be installed from [[http://wch.cn/download/CH341SER_ZIP.html]]. 
 +For Arduino Duemilanove, additional drivers can be installed from  
 +[[https://www.ftdichip.com/Drivers/CDM/CDM21228_Setup.zip]] 
 </WRAP> </WRAP>
 ===== -. Theoretical Study ===== ===== -. Theoretical Study =====
Line 49: Line 58:
  
 <WRAP left round help 100%> <WRAP left round help 100%>
-  * What is the relation between processing gain and spreading factor in LoRa modulation? Explain.+  * What is the relation between processing gain and spreading factor in LoRa modulation?
   * How does the spreading factor impact the coverage of a LoRa transmitter?    * How does the spreading factor impact the coverage of a LoRa transmitter? 
   * What is the transmission bit rate for each of the following configurations of your LoRa device? Explain your computation.   * What is the transmission bit rate for each of the following configurations of your LoRa device? Explain your computation.
Line 107: Line 116:
 ==== -. Running Basic Sketches ==== ==== -. Running Basic Sketches ====
  
-Now you can compile and upload the client and server sketches on the two arduino devices, respectively. On the serial interfaces, you should obtain similar results as in Fig. 2 and Fig. 3. The client sends periodically a short message towards the server. The server outputs the RSSI (received power in dBm) for each received message.+Now you can compile and upload the client and server sketches on the two arduino devices, respectively. On the serial interfaces, you should obtain similar results as in Fig. 2 and Fig. 3. The client sends periodically a short packet towards the server. The server outputs the RSSI (received power in dBm) for each received packet.
  
 [{{ :client-iotlab1.png?direct&600 ||Figure 2. Client serial monitor}}] [{{ :client-iotlab1.png?direct&600 ||Figure 2. Client serial monitor}}]
Line 117: Line 126:
 ==== -. Time on Air ==== ==== -. Time on Air ====
  
-In this section, you will measure the Time on Air (ToA) that is given by the time necessary to transmit a message on the radio interface. You will assess the impact of the spreading factor, bandwidth, coding rate, and message size on the ToA.+In this section, you will measure the Time on Air (ToA) that is given by the time necessary to transmit a packet on the radio interface. You will assess the impact of the spreading factor, bandwidth, coding rate, and packet size on the ToA.
  
-Start by implementing a function on the client that measures the time necessary for sending a message. You can have recourse to the [[https://www.arduino.cc/en/Reference/Micros| micros()]] function available in the arduino libraries. Now, you can modify one of the parameters (spreading factor, bandwidth, coding rate, message size) and record the impact on the ToA. Note well that you may need to repeat the experiment multiple times in order to obtain the statistical distribution.+Start by implementing a function on the client that measures the time necessary for sending a packet. You can have recourse to the [[https://www.arduino.cc/en/Reference/Micros| micros()]] function available in the arduino libraries. Now, you can modify one of the parameters (spreading factor, bandwidth, coding rate, packet size) and record the impact on the ToA. Note well that you may need to repeat the experiment multiple times in order to obtain the statistical distribution.
  
-For example, the scenario for assessing the impact of the spreading factor on the ToA consists of sending 100 messages for three different spreading factors //e.g.,// 7, 9, and 10, and drawing the average ToA or the distribution in a boxplot for comparing the results.+For example, the scenario for assessing the impact of the spreading factor on the ToA consists of sending 100 packets for three different spreading factors //e.g.,// 7, 9, and 10, and drawing the average ToA or the distribution in a boxplot for comparing the results. 
 + 
 +As for the theoretical computation of the ToA, you can refer to the the following documents :  
 + 
 +  * The Semtech [[http://semtech.com/uploads/documents/DS_SX1276-7-8-9_W_APP_V5.pdf| specification]] (section 4.1.1.6)  
 +  * An explanatory video: https://www.youtube.com/watch?v=C_Rh5GSENA4  
 +  * Various calculation tools available online: https://www.loratools.nl/#/airtime, [[https://docs.google.com/spreadsheets/d/1voGAtQAjC1qBmaVuP1ApNKs1ekgUjavHuVQIXyYSvNc/edit?usp=sharing |Spreadsheet]] 
 + 
 +Note that all messages sent and received by the [[https://www.airspayce.com/mikem/arduino/RadioHead/classRH__RF95.html| RH_RF95 RadioHead]] driver we are using conform to this packet format: 
 + 
 +  * 8 symbol PREAMBLE 
 +  * Explicit header with header CRC (handled internally by the radio) 
 +  * 4 octets HEADER: (TO, FROM, ID, FLAGS) 
 +  * 0 to 251 octets DATA 
 +  * CRC (handled internally by the radio)
  
 <WRAP center round help 100%> <WRAP center round help 100%>
Line 146: Line 169:
  
 The setting for this experiment is unique: The setting for this experiment is unique:
- 
   * Only one server is required in the classroom. This server should compute the ratio of successfully delivered packets or PDR.   * 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.   * 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. +  * The average packet arrival rate is equal for all clients. The delay between two packets is drawn uniformly in a predefined interval.
  
 <WRAP center round help 100%> <WRAP center round help 100%>
Line 167: Line 189:
   * Provide the expression of the link budget and compute the received power using two different pathloss models.   * Provide the expression of the link budget and compute the received power using two different pathloss models.
   * Compare the received power obtained experimentally with the theoretical results.   * Compare the received power obtained experimentally with the theoretical results.
-  * Write an article (blog, wiki, ...) to describe your experiment.+  * Prepare a short presentation to describe your experiment. 
 +</WRAP> 
 + 
 +<WRAP center round important 75%> 
 +This challenge and the corresponding grading is considered as a part of the final project.
 </WRAP> </WRAP>
 ===== -. Grading ===== ===== -. Grading =====
  
-|                          ^ Exemplary            ^ Accomplished       ^ Developing         ^ Beginning          ^ +|                                         ^ Exemplary                                                                                                                                                                                  ^ Accomplished                                                                                                                                                      ^ Developing                                                                                                                                                  ^ Beginning                                                                                                                                                   ^ 
-^ Answer to questions      |                      |                    |                    |                    | +^ Techniques for Engineering Practice     | Students showed proper and justified use of techniques necessary for engineering practice (such as numerical methods, stochastic processes, statistical analysis, etc.).                   | Students used techniques necessary for engineering practice without justification (such as numerical methods, stochastic processes, statistical analysis, etc.).  | Students improperly used some techniques necessary for engineering practice (such as numerical methods, stochastic processes, statistical analysis, etc.).  | Students improperly used some techniques necessary for engineering practice (such as numerical methods, stochastic processes, statistical analysis, etc.).  | 
-^ Design experiments       |                      |                    |                    |                    | +^ Skills for Engineering Practice         | Students showed advanced skills necessary for engineering practice (such as programming, drawing and manipulating equipment).                                                              | Students showed skills necessary for engineering practice of the Labs (such as programming, drawing and manipulating equipment).                                  | Students showed limited skills necessary for engineering practice (such as programming, drawing and manipulating equipment).                                | Students showed no skills necessary for engineering practice (such as programming, drawing and manipulating equipment).                                     | 
-^ Analyse results          |                      |                    |                    |                    |+^ Engineering tools                       | Students showed advanced ability to properly use modern engineering tools that are necessary for the Labs, such as simulators, software or computer tools.                                 | Students showed limited use of modern engineering tools that are necessary for the Labs, such as simulators, software or computer tools.                          | Students showed improper use of modern engineering tools that are necessary for the Labs, such as simulators, software or computer tools.                   | Students showed no use of modern engineering tools that are necessary for the Labs, such as simulators, software or computer tools.                         | 
 +^ Problem solving                         | Students solved an engineering problem by choosing appropriate tools and applying engineering skills with proper justification.                                                            | Students solved an engineering problem by choosing appropriate tools and applying engineering skills.                                                             | Students solved an engineering problem but tools were not appropriate and engineering skills not applied.                                                   | Students did not solve the engineering problem.                                                                                                             | 
 +^ Results and analysis                    | Students presented the Labs results and performed analysis, assessment, and comparison with theoretical results.                                                                           | Students presented the Labs results and performed analysis and assessment.                                                                                        | Students presented the Labs results without analysis.                                                                                                       | Students did not present the Labs results.                                                                                                                  | 
 +^ Motivation, initiative, and creativity  | Students were motivated during the Labs. They took initiative, made their own decisions, and came up with new and creative ideas, propositions, and solutions.                             | Students showed motivation for their Labs. They were able to take initiatives to make their work advance.                                                         | Students showed little/unstable motivation. Little initiative has been taken.                                                                               | Students were passive with no motivation. They did not take any initiative in their work.                                                                   | 
 +^ Written communication skills            | Students provided an organized and thouroughly proof-read document with appropriate structure and formatting (figure labels, headings, references, graphs, etc.), and relevant semantics.  | Students provided an organized document with appropriate structure, and relevant semantics, containing minor misspellings and/or grammatical errors.              | Students provided a document with appropriate structure, and poor semantics, containing minor misspellings and/or grammatical errors.                       | Students provided a document with inappropriate structure and formatting, and poor semantics, containing major misspellings and/or grammatical errors.      | 
 +^ Scientific referencing                  | Original work. Proper referencing of material (parts/sentences/figures) quoted from relevant sources.                                                                                      | Original work. Proper referencing of material (parts/sentences/figures).                                                                                          | Proper referencing of quoted material (parts/sentences/figures) but over-reliance on external sources.                                                      | All copied material (parts/sentences/figures) from other sources is not referenced. Reports cannot be submitted as is and must be rewritten.                |
exploring_lora.txt · Last modified: 2021/10/20 12:52 by samer