WMM Power Save increases the efficiency and flexibility of data transmission. Specifically, the client device can doze between packets to save power, while the access point buffers downlink frames. The application chooses the time to wake up and receive data packets to maximize power conservation without sacrificing Quality of Service.
FAQ
Multimedia
Wi-Fi Alliance estimates that WMM Power Save can provide from 15 to 40% improvement in battery life depending on the application characteristics.
If implemented correctly, WMM Power Save will activate automatically when a Wi-Fi CERTIFIED™ for WMM Power Save client device is communicating with a Wi-Fi CERTIFIED™ for WMM Power Save access point. There is no action needed from a user.
WMM Power Save uses mechanisms from the IEEE 802.11e standard.
WMM Power Save builds on the successful WMM (Wi-Fi Multimedia) program, which certifies a set of features for Wi-Fi networks to improve the user experience for voice, video, and audio applications. WMM Power Save is an optional component of the WMM program that targets power consumption when using those applications.
WMM Power Save is a more finely tuned power save mechanism which draws on a variety of tools to manage power consumption. In legacy power save, the driver decided when to transmit data, while in WMM Power Save, the application makes the determination about when to transfer data. This enables customization of the power mechanism to the particular application (e.g., Voice over Wi-Fi, video gaming, etc.). WMM Power Save is backwards-compatible with legacy power save.
Yes. WMM Power Save clients can be used in legacy mode without upgrading WMM Power Save. WMM Power Save Access Points support legacy power save clients simultaneously with WMM Power Save Clients.
Look for the Wi-Fi CERTIFIED™ logo or designation on product packaging, or check the interoperability certificate. Users can also find products that have been Wi-Fi CERTIFIED™ for WMM Power Save by using the product search tool at www.wi-fi.org.
Wi-Fi CERTIFIED™ for WMM (Wi-Fi Multimedia) provides multimedia enhancements for Wi-Fi® networks that improve the user experience for audio, video, and voice applications.
The Wi-Fi Alliance defined WMM as a profile of the IEEE 802.11e Quality of Service (QoS) extensions for 802.11 networks and started a certification program for WMM to satisfy the most urgent needs of the industry for a QoS solution for Wi-Fi networks. WMMprovides prioritized media access and is based on the Enhanced Distributed Channel Access (EDCA) method.
Yes. Devices that are Wi-Fi CERTIFIED™ for WMM also must pass baseline Wi-Fi certification and will interoperate with legacy devices.
WMM certification is required for all Wi-Fi CERTIFIED n products. For products Wi-Fi CERTIFIED for 802.11 a/b/g, the certification is optional, as not all devices need QoS capabilities.
Without Quality of Service (QoS), all applications running on different devices have equal
opportunity to transmit data frames. That works well for data traffic from applications such as web browsers, file transfers, or email, but it is inadequate for multimedia applications. Voice over Internet Protocol (VoIP), video streaming, and interactive gaming are highly sensitive to latency increases and throughput reductions, and require QoS. WMM defines four access categories (voice, video, best effort, and background) that are used to prioritize traffic to provide enhanced multimedia support.
WMM shortens the time between transmitting packets for higher priority traffic.
The comprehensive over-the-air testing program provides detailed measurements on key parameters, described in layperson terms below. The measurements are taken in a 360-degree environment in order to create “real-world” conditions:
- Measurements to provide information about the reach of a Wi-Fi radio signal sent by a converged phone or AP, called transmit power (TRP, or Total Radiated Power)
- Measurements to provide information about how well the Wi-Fi radio can detect an incoming signal in a converged phone or AP, called receive sensitivity (TIS, or Total Isotropic Sensitivity)
In addition, the program includes:
- Measurement of the signals ahead of the Wi-Fi antenna, called conducted power and sensitivity
- Measurement of the reduction in sensitivity (desensitization) of a Wi-Fi receiver caused by the presence of an active cellular transmitter, and to ensure that the performance of the Wi-Fi receiver is within acceptable limits
- Measurements of the desensitization of a cellular receiver caused by the presence of an active Wi-Fi transmitter, and to ensure that the performance of the cellular receiver is within acceptable limits
To complete the testing a device must also be Wi-Fi CERTIFIED™ for core Wi-Fi interoperability and WPA2™ security, and CTIA certified for cellular performance.
WMM-Admission Control used IEEE 802.11 management frames for the signaling between the AP and the client device. The AP evaluates the request frame from the client device against the network load and channel conditions. If the AP can accommodate the request, it accepts the request and grants the client the medium time for the traffic stream. If the request is rejected, the client device is not allowed to initiate the requested traffic stream, and may decide to either delay the traffic stream, associate with a different AP, or establish a best-effort traffic stream outside the operation of WMM-Admission Control.
On a Wi-Fi network with a dense Wi-Fi deployment designed to support heavy traffic loads, such as an enterprise campus, hospital or educational campus, WMM-Admission Control helps ensure that the network can support good quality voice calls before admitting the voice call traffic stream, and assigns it priority over other traffic, such as downloads, email, and other best effort traffic.
WMM-Admission Control further enhances the QoS introduced by WMM, with capabilities to support voice traffic by managing traffic streams depending on the availability of network resources. WMM-Admission Control is an optional certification, and is not required for WMM certification.
WMM-Admission Control certification is required for the Voice-Enterprise certification program.
To benefit from WMM-Admission Control functionality, both the AP and client device need to be Wi-Fi CERTIFIED WMM-Admission Control. Any Wi-Fi CERTIFIED client devices in a WMM-Admission Control network that do not support WMM-Admission Control will operate as usual in WMM mode, but won’t use the access categories for which admission control is mandated by the AP.
Look for the Wi-Fi CERTIFIED™ WMM®-Admission Control designation on product packaging or check the interoperability certificate. Users can also find products that have been Wi-Fi CERTIFIED for WMM-Admission Control by using the product search tool at www.wi-fi.org.
Wi-Fi CERTIFIED TDLS devices implement technology enabling them to link directly to one another when connected to a traditionanl Wi-Fi network. Wi-Fi CERTIFIED TDLS devices can set up secure links and transfer data directly between them. TDLS-linked devices benefit from an optimized connection to do things such as streaming video or synching content, without burdening the network as a whole.
TDLS operates in the background of a Wi-Fi network to optimize performance, while Wi-Fi Direct-certified devices can quickly connect to one another while on the go, even when a Wi-Fi network is unavailable. Many devices will be certified for both solutions and use them in different situations.
No. Two client devices that are Wi-Fi CERTIFIED TDLS can set up a direct connection after linking to the Wi-Fi network, regardless of the technology found in the AP. The two devices will negotiate to operate at the highest level of performance and security common to both devices.
Two Wi-Fi CERTIFIED TDLS devices will automatically form a direct connection after linking to the Wi-Fi netowork. No user interaction is required.
Miracast is an interoperability test program for products that provide seamless wireless display of content, including graphical, video and audio content, across Wi-Fi devices—anywhere, at any time, without cables or even a connection to a Wi-Fi network. Equipment that passes the testing is designated “Wi-Fi CERTIFIED Miracast.”
Miracast is the brand for the certification program operated by the Wi-Fi Alliance. Devices that pass this certification testing can be referred to as “Miracast devices”. Miracast certification is based on the Wi-Fi Alliance Wi-Fi Display Specification. This is the underlying technological specification developed by Wi-Fi Alliance members, and is copyrighted and owned by the Wi-Fi Alliance.
Miracast is an optional certification program for video-capable devices, such as TVs, handsets, tablets, laptops, over-the-top set-top boxes, cameras and projectors.
To enjoy Miracast, both the display and the source devices must be certified for Miracast. Miracast may be used on devices without embedded Wi-Fi through the use of a Miracast-certified adapter that supports an interface such as High-Definition Multimedia Interface (HDMI) or Universal Serial Bus (USB).
Miracast certification testing ensures that devices interoperate across vendors, provide simplified discovery and setup, and implement content protections if premium content is supported. Miracast devices are also tested for implementation of WPA2™ security.
Miracast uses many of the building blocks that, over the years, have enriched the user experience and increased their trust in Wi-Fi, including Wi-Fi CERTIFIED n (improved throughput and coverage), Wi-Fi Direct™ (device-to-device connectivity), Wi-Fi Protected Access® 2 (WPA2™) (security), Wi-Fi Multimedia™ (WMM®) (traffic management) and Wi-Fi Protected Setup™. Some Miracast devices will also support Tunneled Direct Link Setup (TDLS), which allows them to connect via an infrastructure network.
Miracast is expected to directly benefit from continuous advances in Wi-Fi performance, such as those offered by the upcoming 5 GHz program, based on 802.11ac.
Wi-Fi Direct allows devices to connect directly to each other, without the need for a Wi-Fi AP, and often requiring just the push of a button. Wi-Fi Direct allows source and display devices to discover one another and provides the underlying device-to-device connectivity for Miracast. Miracast builds upon Wi-Fi Direct with mechanisms to negotiate video capabilities, setup content protection (if needed), stream content, and maintain the video session.
For video, Miracast supports the ITU-T H.264 video codec (AKA Advanced Video Coding [AVC]) for high-definition video. It supports the Constrained Baseline Profile (CBP) and the Miracast-specific Constrained High Profile (CHP), at levels ranging from 3.1 to 4.2. Supported display resolutions include common Consumer Electronics Association (CEA) formats, Video Electronics Standards Association (VESA) formats, and handheld formats.
For audio, Miracast supports a number of Linear Pulse-Code Modulation (LPCM), Advanced Audio Coding (AAC), and Dolby Advanced Codec 3 (AC3) modes.
Miracast supports High-bandwidth Digital Content Protection (HDCP) 2.0/2.1. HDCP 2.x is a wireless adaptation of the same trusted content protection mechanisms widely used for cabled interfaces, providing diversity in premium content options. This feature is designed to protect the digital rights of content owners and to encourage their efforts to make their content available.
Audio-only devices are not part of the Miracast certification program.
The term “Wi-Fi CERTIFIED Miracast™” designates products that have been certified. The underlying specification or technology is called “Wi-Fi Alliance Wi-Fi Display Specification”. Only products which have completed and passed Wi-Fi certification to the Wi-Fi Display test plan may use the Miracast name. Never use Wi-Fi Display, WFD, or other variants. On second instance, you may refer to “Miracast” products (dropping the term Wi-Fi CERTIFIED). There is no special logo or visual indicator for Miracast.