Wi-Fi devices are operating in increasingly congested bands, whether in homes, enterprises, stadiums or hotspots. Neighboring Wi-Fi devices create interference, which causes a significant drop in network capacity and user experience. The problem is likely to worsen because by 2020 it is expected that there will be more than 20 Wi-Fi devices per home. There is also demand to increase the performance of Wi-Fi over larger spaces indoors and outdoors and to deploy such networks with the least amount of upfront and ongoing effort. Unfortunately, Wi-Fi 802.11ac (11ac) was not originally designed to tackle these interference issues so it must evolve to increase capacity in dense environments. Further, new Wi-Fi receivers are needed to deal with interference introduced by devices competing for the same channel which leads to massive throughput reduction. New features in self-organizing networks further enhance user experience by seamlessly managing signal de-confliction to ensure maximum network capacity performance.
Key Research Areas:
Qualcomm Research, a division of Qualcomm Technologies, Inc., continues to lead the industry with designs for Wi-Fi deployments and is highly involved in IEEE 11ac, 11ax, and WFA (Wi-Fi Alliance) standardization and continue to work within the standard to design and develop technical proposals for AX, where our goal is to achieve 4x throughput improvement in dense environments which have many access points and numerous clients.
In designing the earlier AC standard, we led the design for increasing single link performance and introducing downlink multi-user MIMO. As we move towards the future, we recognize the need for a new breed of Wi-Fi that can accommodate hundreds of devices seamlessly and are completing that work now.
Unlike AC, where devices contend for channel access, uplink transmissions in AX are scheduled by the AP (Access Point) so there will no longer be collision even when many devices are served by the same AP. This ensures uplink transmissions increases network throughput, significantly improving QoS (Quality of Service) and network efficiencies, in comparison to the legacy CSMA-based access protocols. A key technology innovation we introduced was the Uplink (UL) Multi-user protocol, which enabled multiple devices to simultaneously transmit to the AP.
Improving Single Link Throughput
The AX standard is also designed for better single-link performance than AC. By modifying the waveform's parameters, AX has a higher peak throughput and is more efficient and robust when operating in outdoor environment.
Enabling Multi-User Transmissions: An Innovation Breakthrough
While scheduling helps to reduce collisions and increase throughput, the true game changer is being able to conduct multi-user transmissions, which greatly increases capacity. AX introduces multiple uplink simultaneous transmissions, delivering significantly higher network throughput. This involves changes to the PHY and MAC layer standard. To implement such a feature, challenges such as timing synchronization must be overcome. Qualcomm Research's vision has enabled hundreds of devices to be connected to a single AP, allowing multiple simultaneous uplinks.
At the 2016 Mobile World Congress (MWC), Qualcomm Research demonstrated a live over-the-air (OTA) prototype, proving the performance of UL multi-user protocol. We showed robust operation of power control, timing synchronization, and advanced receiver processing, leading to a 4x improvement in UL throughputs using a 4 AP antenna system.
In dense Wi-Fi deployment scenarios, hidden nodes and collisions can create a tremendous amount of interference which causes a significant drop in network throughput. Leveraging our significant cellular experience, Qualcomm Research is developing our Advanced Receiver to mitigate interference and improve device performance, enabling high throughputs to be achieved.
Proving Our Advanced Receivers' Capabilities
During the 2017 MWC, we showed a dense residential scenario where a user device uploaded data to an Access Point (AP) in the same apartment, while it faced interference from multiple hidden neighboring devices, leading to a significant drop in user throughput. To counter this, we then activated our Wi-Fi Advanced Receiver at the AP to suppress the interference and deliver an incredible 2x - 3x throughput improvement, restoring a significant bulk of the original throughput before the interference was introduced.
Previous work done by Qualcomm Research in the area of Wi-Fi SON is easing the deployment of such networks and making them more robust, especially in large and/or dense environments. Many AP (Access Point) products on the market now include Wi-Fi SON.
We are developing a comprehensive set of innovations that greatly simplifies home Wi-Fi networking, providing much improved user experience and optimized whole home connectivity. Qualcomm® Wi-Fi SON solution from Qualcomm Technologies, Inc., uses Wi-Fi APs and plug-and-play Range Extenders (REs) to intelligently utilize all available radio resources using algorithms such as smart band steering, AP steering and adaptive path selection (APS). We designed Wi-Fi SON to ensure that a Wi-Fi device seamlessly connects to the best possible AP or RE for varying network conditions resulting in the best possible user experience. While some the features have already been commercialized, more are being developed. The latest addition to the Wi-Fi SON feature suite are Interference Avoidance Steering and Single AP Smooth Channel Switching.
As the penetration of Wi-Fi increases, the likelihood of having other Wi-Fi networks operating on the same channel, and thus causing interference to a Wi-Fi client, increases. When the source of such interference is hidden from the AP, the Wi-Fi client may see degraded performance in spite of the strong signal from its serving AP. Interference Avoidance Steering preserves the performance of the client in such scenario by taking into account its performance metrics to determine when it is optimal to steer the client to another channel or band with less interference.
In the above scenario, the AP helps a single client subject to avoid interference by steering it to a clean channel. When multiple clients served by an AP suffer from interference, the Single AP Smooth Channel Switching algorithm goes one step further and changes the operating channel of the AP. All the clients are subsequently switched to the new clean channel.
These algorithms run continuously to ensure fast response to changes in interference. The channel or band switching happens without causing any noticeable interruption in service.
If you find the work we're doing in Wi-Fi to be exciting, and you have a technical background in Wi-Fi design, standardization, interference mitigation, receivers, or Wi-Fi SONs, we'd love to hear from you. Please visit us at www.qualcomm.com/company/careers to submit your resume'.
Wi-Fi Advanced Receiver demo video
Feb 22, 2017
11ax Uplink Multi-User Performance
Feb 17, 2016
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Wi-Fi Advanced Airbrush Overview
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