If the application already knows the network SSID that it wants to join than it can set up a connection profile with that information and attempt to join the network. However, there are applications that first need to dynamically determine what infrastructure, adhoc or Wi-Fi Direct networks are in the area, and then decide which network to join. The scan API functions are used to gather this information.
There are 2 types of scan operations
- Active Scan
STA will transmit probe request frames and AP/routers will respond by transmitting probe response frames. For AP/Router with hidden SSID, active scan is used.
- Passive Scan
AP/router will continuously transmit beacon frames for every beacon interval (BI), any STAs may/will receive these beacons and know of existence of this AP/router.
Scanning operation is tied to channel list (MY_DEFAULT_CHANNEL_LIST).
For example,
#define MY_DEFAULT_CHANNEL_LIST {1, 3, 6}
specifies scanning operation will be conducted in channels 1, 3, 6.
In FCC regional domain, there are channels 1 to 11. And among these channels, channel 1, 6 and 11 are defined as social channels.
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Name |
Description |
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Scan operation and type of information contained in scan results | |
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Describes the factors influencing scan or connection duration | |
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Describes the use of macro #define MY_DEFAULT_CHANNEL_LIST | |
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Describes the maximum scan results supported by MRF24W RF modules | |
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Functions and variables accessible by the stack application |