exploring_lora
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exploring_lora [2018/09/29 23:42] – [5. Coverage Challenge] samer | exploring_lora [2018/10/22 15:18] – [5. Coverage Challenge] samer | ||
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In order to design and implement experiments with LoRa, you will use the following devices: | In order to design and implement experiments with LoRa, you will use the following devices: | ||
- | * Arduino Mega (x2). | + | * Arduino Mega or Arduino Duemilanove |
* LoRa shields from [[http:// | * LoRa shields from [[http:// | ||
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* Give the main characteristics of the LoRa shield from Dragino (www.dragino.com). | * Give the main characteristics of the LoRa shield from Dragino (www.dragino.com). | ||
* What type of Antenna are you using? Explain the corresponding characteristics. | * What type of Antenna are you using? Explain the corresponding characteristics. | ||
- | * Give an estimated cost of your platform. | + | * Give an estimated cost of your devices. |
</ | </ | ||
- | |||
==== -. Software Tools ==== | ==== -. Software Tools ==== | ||
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<WRAP center round tip 75%> | <WRAP center round tip 75%> | ||
- | Note well the location | + | Make sure to restart your computer after the installation |
</ | </ | ||
+ | |||
+ | |||
==== -. Installation ==== | ==== -. Installation ==== | ||
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Connect the two Arduino devices to USB ports on your computer. If this is the first time you use Arduino IDE, make sure to install the necessary USB drivers by selecting '' | Connect the two Arduino devices to USB ports on your computer. If this is the first time you use Arduino IDE, make sure to install the necessary USB drivers by selecting '' | ||
- | Now, you have to choose the '' | + | Now, you have to choose the '' |
<WRAP center round tip 75%> | <WRAP center round tip 75%> | ||
- | For Arduino Mega 2560, additional drivers for Microsoft Windows can be installed from [[http:// | + | For Arduino Mega 2560, additional drivers for Microsoft Windows |
- | </WRAP> | + | For Arduino Duemilanove, |
+ | [[https:// | ||
+ | </ | ||
===== -. Theoretical Study ===== | ===== -. Theoretical Study ===== | ||
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<WRAP left round help 100%> | <WRAP left round help 100%> | ||
- | * What is the relation between processing gain and spreading factor in LoRa modulation? | + | * 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? | ||
- | * For each of the three possible | + | * What is the transmission bit rate for each of the following |
+ | * Configuration 1: channel bandwidth = 125 kHz, spreading factor = 7, coding rate = 4/5 | ||
+ | * Configuration 2: channel bandwidth = 500 kHz, spreading factor = 7, coding rate = 4/5 | ||
+ | * Configuration 3: channel bandwidth = 125 kHz, spreading factor = 12, coding rate = 1/2 | ||
* Compute the receiver sensitivity, | * Compute the receiver sensitivity, | ||
* Compare the computed sensitivity to that provided by the {{ : | * Compare the computed sensitivity to that provided by the {{ : | ||
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==== -. Modifying the Radio Parameters ==== | ==== -. Modifying the Radio Parameters ==== | ||
- | Download the {{ : | + | Download the {{ : |
- | Take a look at the source code in '' | + | Take a look at the source code in '' |
- | * Central frequency | + | * Central frequency |
- | * Spreading Factor | + | * Spreading Factor |
- | * Bandwidth | + | * Bandwidth |
- | * Coding Rate (CR) | + | * Coding Rate |
- | * Transmit power (Pow) | + | * Transmit power |
<code c++> | <code c++> | ||
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</ | </ | ||
- | In order to reduce collisions, configure the central frequency of your LoRa devices as indicated below: | + | In order to reduce collisions |
^ Group Number | ^ Group Number | ||
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| | | | ||
| | | | ||
- | |||
==== -. 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 | + | 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 |
[{{ : | [{{ : | ||
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==== -. 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 | + | In this section, you will measure the Time on Air (ToA) that is given by the time necessary to transmit a packet |
- | Start by implementing a function on the client that measures the time necessary for sending a message. For example, you can use the [[https:// | + | Start by implementing a function on the client that measures the time necessary for sending a packet. You can have recourse to the [[https:// |
+ | |||
+ | 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:// | ||
+ | * An explanatory video: https:// | ||
+ | * Various calculation tools available online: https:// | ||
+ | |||
+ | Note that all messages sent and received by the [[https:// | ||
+ | |||
+ | * 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%> | ||
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In this section, you will measure the coverage of LoRa under different radio configurations. | In this section, you will measure the coverage of LoRa under different radio configurations. | ||
- | Start by identifying a set of five geographical locations or Test Points (TP). These TPs should be astutely chosen to explore the limits of LoRa coverage. Then, you should implement a function on the server that measures the ratio of successfully delivered packets or PDR. Now, you should run the experiment for three different radio configurations: | + | Start by identifying a set of five geographical locations or Test Points (TP). These TPs should be astutely chosen to explore the limits of LoRa coverage. Then, you should implement a function on the server that measures the ratio of successfully delivered packets or PDR (Packet Delivery Ratio). Now, you should run the experiment for three different radio configurations: |
<WRAP center round help 100%> | <WRAP center round help 100%> | ||
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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 |
<WRAP center round help 100%> | <WRAP center round help 100%> | ||
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* Direct transmission between the two devices is only considered. | * Direct transmission between the two devices is only considered. | ||
- | * 3D distance is computed between devices. | + | * 3D distance is computed between devices. You can get the elevation from this [[ http:// |
- | * PDR must be higher than 10% as computed for 100 packets. | + | * PDR must be higher than 10% as computed for 100 packets. |
+ | * Supporting live video and screen capture should be used to authenticate the record. | ||
+ | |||
+ | You can use the following online service [[https:// | ||
<WRAP center round help 100%> | <WRAP center round help 100%> | ||
- | * Compute the Fresnel zone for your transmission. | + | * Compute the Fresnel zone for your transmission. Comment the result. |
- | * Provide the expression of the link budget and compute the received power using two different | + | * Provide the expression of the link budget and compute the received power using two different |
* Compare the received power obtained experimentally with the theoretical results. | * Compare the received power obtained experimentally with the theoretical results. | ||
- | * Write an article | + | * Prepare a short presentation |
+ | </ | ||
+ | |||
+ | <WRAP center round important 75%> | ||
+ | This challenge and the corresponding grading is considered as a part of the final project. | ||
</ | </ | ||
===== -. Grading ===== | ===== -. Grading ===== | ||
- | | ^ Exemplary | + | | |
- | ^ Answer | + | ^ Techniques for Engineering Practice |
- | ^ Design experiments | + | ^ Skills for Engineering Practice |
- | ^ Analyse results | + | ^ Engineering tools | Students showed advanced ability |
+ | ^ Problem solving | ||
+ | ^ Results and analysis | ||
+ | ^ Motivation, initiative, and creativity | ||
+ | ^ Written communication skills | ||
+ | ^ Scientific referencing |
exploring_lora.txt · Last modified: 2021/10/20 12:52 by samer