103 lines
2.4 KiB
Markdown
103 lines
2.4 KiB
Markdown
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# | Opportunistic ZigBee |
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## I. Overview
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This project aims to design and optimize a solution for an optimistic network using Arduino and [XBee](https://www.digi.com/xbee).
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The base scenario takes place in a mesh network of similar <u>nodes</u> ; each being subject to real-time motion. Every node has to transmit logging data (*i.e. periodically*) to a special node : the **well ** ; the well is unique in the network and is the only one that actually receives data, every other node has the same source code and behavior.
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**Main goals :**
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1. Optimize network usage : limit duplicates and retransmissions
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2. Maximize relative space-awareness throughout time : avoid losses and retransmissions
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3. [TODO]
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**Vocabulary**
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- **distance** - the relative distance to the well. The well has a distance of 0, its direct neighbors a distance of 1 and so on.
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- **wave** - a distance propagation of distances throughout the network that share a common source.
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----
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## II. File structure
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The code is split over 2 sub-projects :
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- the **well**, located inside `well/main/`.
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- **nodes**, located in the `node/main` folder.
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> The project bundles its required libraries - for compatibility purposes - inside the `libraries/` folder. Symbolic links make them available for each sub-project.
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----
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## III. Algorithm
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#### 1) Data structure
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Every communication follows a consistent data format which can be split into 2 types ; the first *byte* (*i.e. called opcode*) allows receivers to identity the data type.
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##### Discover Request
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The `discover` data format is used to propagate the relative distances throughout the network. The **well** is the only node that can initiate a discover request, other nodes only make sure of the propagation.
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```c++
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struct discover {
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uint8_t opcode; // opcode = 0
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uint8_t wave; // id de la wave
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uint8_t dist; // current node's distance
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};
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```
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##### Data Message
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The `data` format is sent by nodes to submit messagesca to the well.
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```c++
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struct data {
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uint8_t opcode; // opcode = 1
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uint8_t dist; // distance of the last sender
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uint8_t ttl; // time to live default = 10
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uint8_t size; // size of message in bytes
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uint8_t message[]; // actual message
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};
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```
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#### 2) Well
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The well features 2 routines :
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1. Send <u>[discover](#discover-request)</u> requests periodically
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2. Listen for incoming [data](#data-message).
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#### 3) Nodes
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[TODO]
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