Optimize WLAN Design for Wi-Fi Video Transmission

From iptv to FaceTime video, enterprise video applications are growing rapidly. These videos are usually sent and received by mobile devices connected to the enterprise's wireless LAN. Now the network administrator must implement a new WLAN design to optimize Wireless Video Transmission to avoid performance degradation.

The challenges faced by the video WLAN design far exceed the bandwidth limit

When establishing a wireless lan wlan that supports video applications, capacity is obviously a factor to consider, but capacity is not just a simple bandwidth problem. The bandwidth requirements of video applications are affected by the resolution, frame rate, and decoder. For example, a 264 p or P surveillance camera needs to record 6-10 FPS) and uses H.264 encoding, it requires 1 to 2 Mbps bandwidth. However, it may take up to 30 Mbps bandwidth to watch a 72 inch-120 fps hd video.

The decoder can reduce the throughput at the cost of quality, but it supports multi-network TV IPTV) channels. In addition, the image data will also use up the available AP or RF capacity. The popularity of videos in high-density environments, such as classrooms and dormitories, has intensified the competition for online time. Worse, many video streams use multicast to reduce the load on the wired network. However, through Wi-Fi, multicast reduces the distance between the weakest, oldest, and oldest) the data ratio of the client. In a hall filled with various consumer electronic devices, the problem of poor quality must still exist unless further measures are taken to optimize and prioritize video transmission.

Define capacity requirements for wireless video applications

The first step to ensure Wireless Video performance is to establish the network capacity and performance requirements required for video and multimedia applications in WLAN. The Aruba network wireless network supplier recommends the following video categories:

◆ Broadcast IPTV through Wi-Fi. This requires many high-bandwidth 1 to 4 Mbps SD or 6 to 10 Mbps HD) channels for each channel of users to transmit a single row of traffic that is not sensitive to latency.

◆ Live video streaming media broadcast through Wi-Fi ). This requires one-way downstream delivery latency of non-sensitive traffic, especially for all users watching channels that exceed a single high bandwidth of 1-4 Mbps.

◆ IP monitoring video through Wi-Fi. This requires that the uplink or downlink transmission delay is not sensitive to traffic, and a small number of viewers use many channels to deliver videos of different quality from 500 Kbps to 2 Mbps.

◆ Interactive video conferencing. This is a two-way delivery of traffic affected by traffic delay and jitter up to 150 to 200 milliseconds), but both sides need low symmetric bandwidth of 1 Mbps ).

◆ VOD training and pre-recorded programs ). This requires non-sensitive traffic for one-way downlink delivery latency. Each channel has multiple users consuming 1 to 4 Mbps SD channels with high bandwidth or 6 to 10 Mbps HD channels at the same time ).

These examples illustrate the transformation of all video and multimedia WLAN deployment: directionality, throughput, latency and jitter tolerance, as well as the number of channels and users. Another key indicator is the Failover rate. Low packet error rate is usually present, but it can also cause problems for UDP multicast.

Design Considerations: 802.11n Wireless LAN for Wireless Video Delivery

Fortunately, enterprise WLAN products are mature enough to provide a solid foundation for video and other multimedia applications. Video WLAN should use 802.11n to increase capacity, density, and reliability. In terms of functions and Design of 802.11n, the following elements need to be taken into account:

Channel binding and space multiplexing through multi-input, multi-output MIMO) antennas, increase the capability of each radio to 450 Mbps3X3) or 600 Mbps4 × 4) rate, enable each AP to support more video users.

◆ The available throughput of each user will be limited by the Wi-Fi client capability, especially for smartphones and smart phones with 1x1 MIMO up to 65 Mbps, which will decrease with distance) technical tablet. This may be sufficient for a single video stream, but it is important to note that a slow client may pull down the performance of each user's video. This low data rate should be taken into account when designing a WLAN.

◆ Use 802.11n standard options, such as A-MPDUMAC protocol data unit) and block validation to further increase the data throughput of delayed, insensitive unidirectional video streams.

◆ The 802.11n device can support 2.4 GHz and/or 5 GHz. The 5 GHz channel must be fully utilized when higher throughput is required. For example, use the coverage designed by the prediction WLAN planner to replace the AP to meet the throughput, user density, and user rate upstream and downstream bandwidth needs. However, do not think that a strong signal will produce high-quality videos. You must always verify the performance.

◆ Use Wi-Fi multimedia WMM) priority to give videos more online time than data, but it does not consume all available bandwidth. Applications with latency and jitter, such as VoIP and video conferencing, have higher priority than unidirectional data streams. WMM access control may help avoid excessive load on one AP.