doc: wifi: siwx91x: Add Wi-Fi features documentation
Added Wi-Fi specific documentation and linked it to the SiWx917 pages. Signed-off-by: Muzaffar Ahmed <muzaffar.ahmed@silabs.com>
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Benjamin Cabé
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boards/silabs/radio_boards/common/wifi.rst
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boards/silabs/radio_boards/common/wifi.rst
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.. _siwx917_wifi_features:
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SiWx917 Wi-Fi Features (Alpha)
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##############################
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Overview
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========
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This document provides an overview of the 917 Wi-Fi module's capabilities and
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features, focusing on its STA and Soft-AP modes.
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STA Mode Features
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=================
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The STA (Station) mode of the 917 Wi-Fi module provides robust functionality
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for connecting to wireless networks as a client. Below are the key features:
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Scan
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----
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The STA mode supports network scanning to identify available access points:
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- **Active Scanning**: Actively probes for nearby networks.
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- **Passive Scanning**: Listens for beacon frames to discover networks.
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- **Background (BG) Scanning**: Supports background scanning to identify
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better access points without interrupting the active connection.
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The module supports up to **11 scan results** at a time, ensuring efficient
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discovery of nearby access points.
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The module supports only one SSID that can be specified for SSID filtering.
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Active and Passive scanning are performed when the device is not in associated
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state.
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BG Scanning is performed when the device is in associated state.
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If channel is not provided, the device will scan all the valid channels.
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The default active dwell time is 100 ms.
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The default passive dwell time is 400 ms.
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Security
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--------
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The module incorporates advanced security measures to ensure a safe and
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reliable connection. It supports the following security modes:
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- **Open**: No encryption, suitable for unsecured networks.
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- **WPA (Wi-Fi Protected Access)**: Provides improved security over WEP.
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- **WPA2 (Wi-Fi Protected Access II)**: Industry-standard encryption for
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most networks.
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- **WPA3 (Wi-Fi Protected Access III)**: Enhanced encryption and protection
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against modern threats.
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- **WPA2-SHA256**: Enhanced WPA2 security using SHA256 for improved
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cryptographic strength.
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- **WPA3 Transition Mode (WPA2+WPA3)**: Ensures compatibility with networks
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that use both WPA2 and WPA3 security standards.
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These modes ensure that the module can connect securely to a wide range of
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networks while maintaining strong data protection.
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Link Modes
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----------
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To ensure compatibility with diverse networks, the module supports multiple
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Wi-Fi link modes:
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- **802.11b (Wi-Fi 0 and Wi-Fi 1)**: Legacy mode with speeds up to 11 Mbps.
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- **802.11g (Wi-Fi 3)**: Enhanced performance up to 54 Mbps.
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- **802.11n (Wi-Fi 4)**: High throughput with MIMO technology.
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- **802.11ax (Wi-Fi 6)**: Next-generation efficiency, capacity, and
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performance.
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Power Save
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----------
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The module implements power-saving mechanisms to optimize energy consumption.
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It supports the following legacy power-saving modes:
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- **DTIM (Delivery Traffic Indication Message) Based**: Reduces power
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consumption by using DTIM intervals to wake up only when buffered data is
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available at the access point.
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- **Listen Interval Based**: Allows the module to wake up periodically based
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on a defined listen interval to check for traffic. The Listen Interval
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will be in units of Beacon Interval.
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The device supports (Power save) Listen Interval ranging from 100 ms - 1000 ms.
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Accordingly, the Listen Interval needs to be configured in units of
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Beacon Interval. If the Listen Interval is configured more than 1000 ms, then
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it takes the value as 1000 ms. The Listen Interval based wakeup will take
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effect once the device is in connected state. If the Listen Interval is set to
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zero, the driver will automatically switch to DTIM wakeup. If power save is
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disabled by firmware than driver will take the previously configured
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Listen Interval when it is enabled.
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This (Power save) Listen Interval shall be less than the Listen Interval
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advertised in (Re)Association Request frame.
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It also supports the below modes to retrieve buffered packets:
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- **PS-Poll (Power Save Polling)**: Enables the device to retrieve buffered
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packets from the access point when it has entered power save mode.
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- **QoS Null Data**: Allows the device to send QoS Null frames to retrieve
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buffered packets from the access point in a power-efficient manner.
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The device enables its proprietary mode Enhanced Max PSP feature to retrieve
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buffered packets by default for improved performance.
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If this feature is disabled through disabling the config flag
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``CONFIG_WIFI_SILABS_SIWX91X_ENHANCED_MAX_PSP``, then QoS Null frame gets
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enabled. Both QoS Null frame and Enhanced Max PSP are mutually exclusive.
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After disconnection, PS gets disabled, thus, PS needs to be enabled again for
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new connection, if required.
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The Monitor Interval is defined as the time from the last packet received
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(except ACK). If there is no packet received till this interval, then the
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device goes to sleep. The default value of Monitor Interval is 50 ms if 0 is
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configured. This is used for QoS Null Data or Enhanced Max PSP. The device
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supports maximum value of Monitor Interval as 1000 ms.
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Currently, ``timeout_ms`` is not supported in the device.
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Management Frame Protection
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---------------------------
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Support for **802.11w** ensures protection for management frames, safeguarding
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against:
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- Deauthentication attacks.
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- Disassociation attacks.
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802.11w is enabled by default.
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**Recommended MFP Values for different security modes:**
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+---------------+-------------+-------------+--------------+
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| Security Mode | MFP Disable | MFP Capable | MFP Required |
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+===============+=============+=============+==============+
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| Open | Yes | | |
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+---------------+-------------+-------------+--------------+
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| WPA | Yes | | |
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+---------------+-------------+-------------+--------------+
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| WPA + WPA2 | | Yes | Optional |
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+---------------+-------------+-------------+--------------+
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| WPA2 | | Yes | Optional |
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+---------------+-------------+-------------+--------------+
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| WPA2 + WPA3 | | Yes | No |
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+---------------+-------------+-------------+--------------+
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| WPA3 | | Yes | Yes |
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+---------------+-------------+-------------+--------------+
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BG Scan and Roaming
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-------------------
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Roaming enables a Wi-Fi STA (Station) to seamlessly transition from one
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Access Point (AP) to another within the same network without losing its
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connection. This ensures uninterrupted connectivity as the STA moves across
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different AP coverage areas.
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The device support **Legacy Roaming**, which comprises the following procedures:
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1. **Background (BG) Scan**:
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- A standard scanning procedure executed while the STA remains connected
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to the network.
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- Triggered when the Received Signal Strength Indicator (RSSI) falls
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below a predefined threshold.
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2. **Roaming**:
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- Initiated when the RSSI crosses the threshold and a roaming hysteresis
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condition is met.
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- The roaming process can be carried out using either an
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**NDP (Null Data Packet)** or a **Deauthentication frame**. The default
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configuration is to use NDP. The configuration can be changed using
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Kconfig ``CONFIG_WIFI_SILABS_SIWX91X_ROAMING_USE_DEAUTH`` to use a
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deauthentication frame for Roaming.
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**Challenges**:
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- The **Zephyr API** does not currently provide an API for Legacy Roaming.
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While APIs for **802.11r roaming** are defined, they do not apply to
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Legacy Roaming.
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**Current Design**:
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- **BG Scan**: Performed using the Scan API.
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- **Roaming Configuration**: Configured during the first BG Scan. Roaming
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parameters are managed through **Kconfig** options.
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Roaming is enabled by default, but BG Scan needs to be performed to initiate
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and configure the Roaming parameters. Roaming can be disabled by disabling the
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config flag ``WIFI_SILABS_SIWX91X_ENABLE_ROAMING``.
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BG Scan stops when the STA gets disconnected. This BG Scan command again needs
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to be given to enable BG Scan and Roaming.
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The device support multi-probe in BG Scan where it can also scan APs with
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different SSID. This configuration can be disabled using Kconfig.
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Target Wake Time (TWT)
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----------------------
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The module supports **Individual Target Wake Time (TWT)** in compliance with
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Wi-Fi 6 standards:
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- **Individual TWT**: Allows the module to negotiate wake times with the
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access point, optimizing power consumption for the device. It supports
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only as a requester.
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- Does not support broadcast TWT.
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This feature is ideal for IoT devices requiring periodic connectivity with
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minimal energy use.
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The device does not support Explicit TWT. It does not support
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TWT Information element.
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The device does not support TWT quick setup. It does not support configuring
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parameters like TWT interval, TWT wake ahead duration and dialog token.
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Bugs and Limitations
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--------------------
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- The default configuration complies with US regulatory domain. Thus, it
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supports Channels 1-11 only, ensuring operation within permitted
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frequencies for the US region.
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- For WPA3 (SAE), our device has a limitation of 64 characters on the
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password.
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- EAP security modes are not supported.
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- The link mode in Wi-Fi status is always ``WIFI_LINK_MODE_UNKNOWN``.
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- The device supports bandwidth of 20 MHz only and 1 spatial stream.
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- 802.11r is not supported.
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- WMM power save mode is not supported.
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Soft-AP Mode Features
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=====================
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In Soft-AP (Software Access Point) mode, the 917 Wi-Fi module can act as an
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access point, allowing other devices to connect to it. Below are the key
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features:
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Security
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--------
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The module provides secure connections for devices connecting to the Soft-AP.
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It supports the following security modes:
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- **Open**: No encryption, suitable for unsecured networks.
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- **WPA (Wi-Fi Protected Access)**: Provides improved security over WEP.
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- **WPA2 (Wi-Fi Protected Access II)**: Industry-standard encryption for
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most networks.
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- **Mixed Mode (WPA+WPA2)**: Ensures compatibility with networks that use
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both WPA and WPA2 security standards.
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These modes allow flexible configurations for devices connecting to the Soft-AP.
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Link Modes
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----------
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Soft-AP mode supports the following link modes:
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- **802.11b (Wi-Fi 0 and Wi-Fi 1)**: Legacy mode for basic connectivity.
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- **802.11g (Wi-Fi 3)**: Enhanced speeds for modern devices.
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- **802.11n (Wi-Fi 4)**: High-speed connectivity for demanding applications.
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Hidden SSID
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-----------
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Allows the network name (SSID) to be concealed from broadcasting. This enhances
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privacy by preventing the SSID from being visible to unauthorized users.
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Bugs and Limitations
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--------------------
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- The default configuration complies with US regulatory domain. Thus, it
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supports Channels 1-11 only, ensuring operation within permitted
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frequencies for the US region.
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- The link mode in Wi-Fi status is always ``WIFI_LINK_MODE_UNKNOWN``.
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- The device supports bandwidth of 20 MHz only and 1 spatial stream.
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- Although STA and BLE can coexist simultaneously, AP and BLE cannot operate
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together.
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@ -34,11 +34,15 @@ Supported Features
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.. zephyr:board-supported-hw::
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Refer to the :ref:`siwx917_wifi_features` page for a list of supported Wi-Fi features.
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Programming and Debugging
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*************************
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.. zephyr:board-supported-runners::
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Flashing
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========
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@ -30,6 +30,9 @@ Supported Features
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.. zephyr:board-supported-hw::
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Refer to the :ref:`siwx917_wifi_features` page for a list of supported Wi-Fi features.
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Programming and Debugging
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*************************
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