The Sona NX611 uses SDIO 3.0 for Wi-Fi and HS-UART for Bluetooth.

The Sona NX611 is a 5.4 spec Dual-Mode Bluetooth radio. The primary Bluetooth features are:

• BDR + EDR + BLE (Classic + BLE)
• LE 2 Mbps PHY
• LE Coded (Long Range PHY)
• Adaptive Frequency Hopping (AFH)
• Secure Simple Pairing (SSP)
• UART baud rates upto 4 Mbps
• 7 x Classic Bluetooth links
• 16 x BLE links
• Secure connection (AES128 & ECC256)

The Sona-NX611 supports two different configurations to use the Bluetooth radio. Each of these methods require that the Wi-Fi firmware loads a specific Bluetooth firmware. The methods are as follows:

btattach

This method uses the traditional btattach implementation for the Bluetooth serial interface. For this method the Wi-Fi firmware must load the sduart_nx61x firmware.
modprobe moal fw_name=sduart_nx61x_v1.bin.se
After the Wi-Fi firmware has loaded the Bluetooth firmware, the btattach command may be issued.
Example:
/bin/nohup /usr/bin/btattach -B /dev/ttymxc0 -P h4 -S 3000000 2>&1 > /dev/null&

serdev

An alternative to btattach is serdev (available in kernel 4.2 or higher). This mechanism is configured in the device tree. Below is a sample device tree snippet that configures the serial port for use with the Sona-NX611 radio on an NXP i.mx 8M+ EVK.
Sample:
&uart1 {
bluetooth {
compatible = "nxp,88w8987-bt";
fw-init-baudrate = <3000000>;
};
};
For this method the Wi-Fi firmware must load the sd_w61x firmware
modprobe moal fw_name=sd_w61x_v1.bin.se

Note: The version numbers of the firmware files will change over time, please use the version that is loaded in your /lib/firmware/nxp directory on your device.

An Ezurio Wi-Fi module can be configured for AP-Sta mode with the following nmcli commands:

• iw dev wlan0 interface add wlan1 type __ap
• nmcli con add con-name myap ifname wlan1 type wifi ssid myapssid autoconnect yes 802.11-wireless.mode ap ipv4.method shared
• nmcli con add con-name mysta ifname wlan0 type wifi ssid mystassid

This is assumes that you have the iw and dnsmasq packages installed in your build.

Note: In the above configuration, the Access Point will follow the channel that the station associates to. Therefore it is reccomended that the client is configured to use a 2.4 GHz channel or the U-NII-1 channels in the 5 GHz band as the Ezurio radios will not work as DFS masters and do not support AP mode in the rest for the 5 GHz channels nor in the 6 GHz band.>

In HW part, need to wire PTA interface in between LTE and NX611. EXT_REQ and EXT_GNT are mandatory pins, EXT_PRI, EXT_STATE and EXT_FREQ are optional.

In SW part, coexistence arbitration mechanism is always operational and it's fixed in firmware. 

Yes, If you decide to use NetworkManager, then systemd-networkd should be removed from the system. We would recommend changing Yocto systemd PACKAGECONFIG to not build it into image.

One of the new features in Wi-Fi 6 is a longer guard interval. The guard interval is used to help mitigate multipath or overlapping transmissions. This is done by adding a delay between symbols (set of 0s and 1s). The shorter the guard interval theoretically the faster the throughput but you are more susceptible to multipath due to metal and other reflective surfaces.

Wi-Fi 4 and 5 supported two guard intervals:

• Short - 0.4 microseconds
• Long - 0.8 microseconds

Wi-Fi 6 supports 3 guard intervals:

• Normal - 0.8 microseconds
• Double - 1.6 microseconds
• Quadruple - 3.2 microseconds

In Wi-Fi 6 the 1024-QAM allows up to a 4x longer symbol duration than in Wi-Fi 5, so the efficiency is still similar to Wi-Fi 5 even with Quadruple guard interval.

What guard interval should I use for various use cases?

A general rule of thumb should be:

• Normal - Use this in a clean open area without a lot of metal. This would also best be used outdoors. Normal Guard Interval is the best choice when throughput is of the utmost importance.
• Double - This is a good compromise between Normal and Quadruple. It will not provide as good of throughput as Normal but will reduce the likelihood of multipath in areas that are smaller or have some metal.
• Quadruple - This would be used in small areas or areas with a lot of metal. This would also be the best choice in areas with a lot of clients to reduce the overhead of retrying packets.

All of the Wi-Fi 6 features are supported in the 2.4 GHz band in a Wi-Fi 6 radio.

This was not the case in Wi-Fi 5. It reverted back to Wi-Fi 4 in the 2.4 GHz channels.

Yes, Laird Wifi modules can be integrated with OpenWRT like with other Linux operating systems.

See Lairds "Guide" Section for an example:

https://www.ezurio.com/documentation/application-note-how-to-integrate-the-60-series-wifi-module-with-openwrt

In the Regulatory Tools package you receive there are many files. The filename structure is:

{radio-type}-{toolchain}-{version}.tar.bz2

For example, the file mfg60n-arm-eabihf-10.135.0.6.tar.bz2 would be for our 60 Series radio running on a system with a GNU Embedded Application Binary Interface (High Float) running version 10.135.0.6 of the Laird firmware. 

An easy way to determine your toolchain is to use the command:

ls -l /ld-linux*

For Regulatory Testing you will be required to load a special firmware to put the radio into "Test Mode". The code for our Wi-Fi modules is available-by-request by opening a case with our Support Team at https://www.ezurio.com/resources/support.