Cell Type in Schedule
- Tengfei Chang
In OpenWSN, there are 5 types of cell as shown in the table below briefly. In this page, we detail the usage of 5 different types of cell.
Cell Type Introducation
| CellType | Description |
|---|---|
| CELLTYPE_OFF | slot that doesn't do anything |
| CELLTYPE_TX | slot for sending packet |
| CELLTYPE_RX | slot for receiving packet |
| CELLTYPE_TXRX | slot for sending/receiving |
| CELLTYPE_SERIALRX | slot for listening data from serial port |
Type Off
The cell with type off basically is only for sending status data. Besides that, Off type cell also used for sending the packet to DAGroot if necessary. Because of this feature, there must be always at least one Off type cell in the schedule.
DAGroot in OpenWSN
Type Tx/Rx
The cell with type Tx/Rx is used for sending dedicated packet to one of its neighbor. The cell with this type associated with a 64-bit address of its neighbor and only allows the packet with the address as receiver address for transmission.
Type TxRx
The cell with type TxRx is used for CSMA communication. The cell with this type associated with any-cast type address and allows any type packet transmission through this type cell.
Type SerialRx
The cell with type SerialRx is used for receiving the data/command coming from the DAGroot. For example, the DAGroot, (openvisualizer part) send DAGroot toggle command to change the status of DAGroot of mote; forwarding the packet from the internet to the mote in the network.
Definition of number of slots in OpenWSN
In OpenWSN, there are several definition about the number of different type of cells. For better utilizing those parameters, we will describe them here.
| Parameter | description | |
|---|---|---|
SCHEDULE_MINIMAL_6TISCH_ACTIVE_CELLS | The number of active cells defined by 6tisch minimal draft. This is the initial number active slot for the network. | |
NUMSERIALRX | The number of cells for receiving serial data from openvisualizer. By default it's set to 3. | |
NUMSLOTSOFF | The number of available slot entries. Those slots can be used as any other type of cells. At initial of the network, those slots are off type. | |
SLOTFRAME_LENGTH | The length of slotframe. |
At the initial of openwsn network, the schedule looks like the table below:
| Cell Type | Cell Number |
|---|---|
| CELLTYPE_TXRX | NUMSERIALRX |
| CELLTYPE_SERIALRX | NUMSERIALRX |
| CELLTYPE_TX | 0 |
| CELLTYPE_RX | 0 |
| CELLTYPE_OFF | SLOTFRAME_LENGTH - NUMSERIALRX - NUMSERIALRX |
After the network is running, NUMSLOTSOFF cells will be used as other type of cells. And the type of those cells depending on the algorithm user implemented. For example, when more bandwidth is required for the entwork. Those OFF cells will be used as TXRX or TX/RX type cells.
