Technologies for Wi-Fi Video Acceleration - Mobile World Live

Technologies for Wi-Fi Video Acceleration

26 FEB 2020

PARTNER FEATURE: In the 5G era, fixed networks enter the gigabit deployment stage, and video becomes a basic service as well as an important filler of bandwidth for operators. Data shows that more than 80 percent of traffic generated by home broadband users comes from Wi-Fi services, with video accounting for the bulk of it. As their industry chain and applications mature, 4K/8K Ultra High Definition (UHD) video services become the core means for operators to build core competitiveness and conduct value-oriented operations of gigabit networks. Because users demand to view content on multiple screens and from anywhere in the home, Wi-Fi will be the main mode of carrying 4K/8K video services in households. Mainstream smart mesh Wi-Fi networking solutions currently on the market can provide the bandwidth required by UHD video services. However, 4K/8K services also have strict requirements for latency, jitter, and packet loss ratio. Technologies such as real-time retransmission of lost Real-time Transport Protocol (RTP) packets, Wi-Fi Quality of Service (QoS) assurance, inter-channel interference reduction, power control optimization, and visual management and fault location are needed to ensure the quality of these services and deliver the best experience for home users.

A mini Content Distribution Network (CDN) can be built into a home gateway to enable video packet caching and Automatic Repeat Request (ARQ) retransmission, resulting in a 90 percent decrease in the packet loss ratio and improving the experience of Over The Top (OTT) video. Streaming requires a packet loss ratio of less than 10-5 to achieve the optimum viewing experience, but Wi-Fi usually incurs 10-4 or more loss because of environmental and other factors. A mini-CDN built in the home gateway can cache the RTP packets of streaming video of a certain duration. When the Set Top Box (STB) discovers that an RTP packet is lost, it sends a re-transmission request to the home gateway. When re-transmitting the packet, the home gateway elevates its priority to shrink latency. See Figure 1.



Figure 1 Mini-CDN Reduces Packet Loss and Enhances Streaming Experience

TCP booster technology avoids out-of-order Wi-Fi transmission and packet loss to accelerate OTT video. This technology divides the TCP connection between the STB and the Internet server into two sections. The section between the home gateway and the Internet server and that between the STB and the home gateway are separately maintained, while packets are sequenced and cached, to prevent video stalling caused by out-of-order Wi-Fi transmission and packet loss. See Figure 2 for details.

Figure 2 TCP Booster Accelerates OTT Video

Different services are intelligently identified and tagged with different priorities to ensure that services are carried over Wi-Fi in a differentiated fashion. When services like web surfing, downloading and gaming are concurrently performed, users’ streaming experience will not be affected. For different service flows, the home gateway can use Deep Packet Inspection (DPI) to identify and tag their priorities. It can also analyze the balance of the network load based on both the service flows and the home network topology. The Wi-Fi Multimedia (WMM) parameters of the services are intelligently configured, and the Airtime Fairness (ATF) mechanism is used to dynamically adjust the airtime of different devices according to the current channel utilization. This guarantees enough airtime for the STB and restricts airtime for the other wireless terminals so that the streaming service is not affected.

Admission control boosts the priority of the upstream packets of the STB to guarantee fast response of the Electronic Program Guide (EPG). A family often needs to watch multiple channels of video at the same time. In a home with multiple Access Points (APs), one AP should carry two channels of 4K/8K video over Wi-Fi. The AP needs to not only provide at least 200Mbsp bandwidth (redundancy included) but also accommodate the competition and balance between multiple wireless terminals. Admission control is enabled on the APs to boost the priority of the upstream packets of the STB to guarantee fast response of the Electronic Program Guide (EPG).

Artificial Intelligence (AI)-based dynamic power optimization and intelligent multi-scenario power adaptation improves video service experience. Wi-Fi signals, especially those in the 5GHz band, attenuate greatly and the packets are prone to error after passing through a wall. The modulation rate is dynamically adjusted, and the power between AP and STB is adapted, to enhance the wall penetration of Wi-Fi signals. In a modern home, there are a large number of wireless devices emitting strong signals. The energy detected in the channel can easily exceed the Clear Channel Assessment (CCA) threshold so that data cannot be sent. The CCA threshold is dynamically adjusted to increase the interference tolerance of the system. The CCA thresholds of the AP and STB can be elevated according to indicators such as channel interference and bit error rate to boost the probability of data being sent. Meanwhile, the APs support using the Transmit Power Control (TPC) technique to control the power of each packet. The signal strength of every terminal is detected in real time and the transmit power of the APs is adjusted dynamically to reduce the interference between the APs and improve the overall throughput of the system.

Channels are monitored and measured in real time or periodically so that their bandwidth can be dynamically adjusted or channel switchover can be performed in the face of interference from a neighboring AP(s). Wi-Fi interference is a major problem currently affecting home networks. The interference mainly comes from a neighboring AP(s). The busy/idle status of every 20M subchannel is monitored in real time. Bandwidth is dynamically adjusted to avoid the interfered-with subchannels. A list of channels currently in the best status is produced through periodic measurement and analysis. When the channel utilization is too high and it affects services, the AP can require that the STB also switch channels. During a channel switchover, the AP and STB keep being associated and do not stop receiving/sending packets. After the switchover, they do not need to establish the association all over again and can continue receiving/sending packets. As a result, channel switchovers can be conducted with zero packet loss, and interference from a neighboring AP(s) becomes a non-issue.

The Aggregate MAC Service Data Unit (A-MSDU) technology is disabled to reduce the probability of aggregate frames being transmitted and improve the video service experience. A Wi-Fi chip aggregates packets before sending the aggregated packet to improve transmission efficiency. When a transmission error occurs, the A-MSDU frame needs to retransmit the entire packet, which is especially the case in an interference-heavy environment and will greatly impair transmission efficiency. Homes have a high concurrency of services including video, web surfing, and gaming. In this scenario, the A-MSDU function can be disabled to decrease the probability of aggregating big packets (video) and small ones (other services), reduce the retransmission of video packets caused by lost small packets, and significantly enhance video transmission efficiency.

Smart self-service installation and maintenance is achieved through a TV and a remote. With the press of a key, the STB can be easily added to the home network, and the STB’s configurations can be automatically delivered. With the press of a key, the home network can be fast scanned and detected. An intelligent diagnosis of the home network can be conducted both locally and in the cloud to address Wi-Fi issues including coverage, interference and load. With the press of a key, the user can optimize the home network.

From Standard Definition (SD) and High Definition (HD) to UHD 4K/8K and VR, user requirements for video quality and experience keep increasing. The technology of carrying 4K/8K over Wi-Fi can comprehensively guarantee services by enabling easy installation and maintenance, efficient deployment, superior experience, and so on. It can help operators upgrade home networks from being bandwidth-centric to being experience-centric and make a strategic transformation.



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