WLAN Linux driver development as per WiFi-6 standard (IEEE 802.11ax)

Introduction:

WiFi6 is the latest in series of WLAN standards developed as per IEEE 802.11ax specification. The 802.11ax defines PHY and MAC layer specifications. It supports 2.4 GHz, 5 GHz and 6 GHz (supported by WiFi 6E) frequency bands. WiFi-6 is successor to WiFi5 (IEEE 802.11ac) and wifi4 (IEEE 802.11n) standards. The article describes wifi6 features, WiFi6 benefits, WiFi6 driver development guidelines etc.

Features of WiFi6: Following are the major features introduced in IEEE 802.11ax standard.

· 8X8 MU-MIMO (DL/UL)

·?OFDMA DL/UL

·?Uplink resource scheduling

·?Long OFDM Symbol

·?1024 QAM modulation support

·?BSS coloring

·?1024/2048 FFT sizes with support for higher channel BWs

Benefits of WiFi6: There are several benefits of WiFi6 compare to previous wifi standards as follows.

·?It offers higher speeds using advanced modulation techniques and efficient use of available BW (Bandwidth). It supports maximum theoretical throughput of 9.6 Gbps.

·?It supports a greater number of client devices simultaneously using advanced technologies such as MU-MIMO, OFDMA and BSS coloring.

·?It performs better in high density environments (stadiums, airports, malls) using spatial reuse and BSS coloring.

·?It uses TWT (Target Wake Time) technique which makes it possible for wifi devices to schedule their usage and hence reduces power consumption. This increases battery life for client devices.

·?It offers enhanced security using WPA3 security algorithm.

·?It is backward compatible with previous WiFi standards.

·?It offers improvement in range with reduction in interference using BSS coloring technique.

WiFi6 Driver development: Following section describes generic steps following during wifi-6 driver development.

• mac80211/softmac: This is the lower layer, and the most associated to hardware offloading. In fact, by definition, whatever code needed here is not provided by the hardware, or is preferred in software to give better control for developers. In short, the 802.11 protocol state machine lives here, for every type of frame mentioned earlier. It is also called as "Soft MAC" module as opposed to "Hard MAC" in which the device's firmware performs all the functionalities.
• cfg80211: This is the middle-layer which handles everything configurable for your WLAN adapters contrary to mac80211. It is mandatory for drivers to interface with this layer. This module acts as a bridge between the kernel and user space.?

• nl80211: This layer acts as API between user-space and kernel-space. It relies on the netlink protocol to exchange messages between these two spaces. It is basically acts as front-end for cfg80211. This helps to generate appropriate events and messages which are required to be listened by the consumers. Netlink is a Linux-specific socket type used for events requiring to cross the kernel-user border. Netlink the program that manages device hot plug and relays hardware events.?
• Hostapd: Hostapd (Host access point daemon) is a user space software access point capable of turning normal network interface cards into access points and authentication servers. The current version supports Linux (Host AP, MADWIFI, mac80211-based drivers) and FreeBSD (net80211).

Aumraj contribution:

We have carried out following activities for one of our prestigious clients.

MAC80211 based softmac driver development:

· Developed/modified pre-patched WLAN driver source code as per IEEE802.11ax

·?Performed driver level testing and functionality validation

Performed openWRT changes:

·?Added a new platform ?

·?Added new WLAN module packages

·?LuCi wifi script customisation

?About Aumraj Design Systems Pvt. Ltd.?

Aumraj is specialized in Embedded hardware, Embedded firmware, Linux device drivers and?Chip design and verification services. ?Our Linux programmers along with WLAN domain knowledge can provide best solutions and deliverables as per customized client requirements. We provide skilled manpower to the clients across the globe and undertakes project execution as per client requirements?in VLSI and embedded domain.

For more information visit https://aumraj.com/?

For specific requirements, be in touch with our business team at [email protected].

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