The section of the website is an introduction to how networks operate.
The networks that allow smooth communications are the most critical component of a telehealth setup. Networks can be extremely complex so most large organisations will have specialist IT support to ensure the correct network architecture is in place. Even with smaller-scale use of telehealth, seeking specialist IT advice is advisable.
In its simplest form a network is a collection of linked computers. Networks can be of any size, from two computers at home, to a small business such as a medical centre, to a large DHB with thousands of computers. Networks can be private, only able to be accessed by approved users, or public where there is free access to the network. The internet is an example of a very large public network.
The internet – upload and download
During a video call, video, audio and other information is exchanged. This information has to be uploaded by one participant then downloaded by the other. This happens simultaneously in both directions with little delay.
Many internet connections are asynchronous, meaning upload and download speeds are different. For example, an ADSL connection may have a download (receive) speed of 8Mb/s but an upload (send) speed of only 0.7Mb/s. This uneven distribution is a challenge for video as generally participants are unable to upload/send at sufficient speed for video. The upload speed will always be a limiting factor.
It is important to remember the public internet is drawn on by a very large number of people, so performance can be good at certain times and poorer at others.
Types of internet connection:
|Dial Up||Not acceptable for video.|
|ADSL & ADSL2||Generally poor quality video.|
|ADSL 2||Generally OK quality for non-clinical situations. Quality will be variable and unreliable.|
|VDSL||Generally excellent quality, 720 pixel resolution HD video.|
|Fibre||Excellent quality, up to 1080 pixels, HD video, with smooth motion.|
Wireless or wired connection?
While WiFi access is extremely convenient, a wired connection is recommended for telehealth whenever possible. This is especially important in clinical applications. The graphic below shows the connection speed achieved on a wired VDSL connection. The green section shows that the connection speed was very consistent.
A WiFi connection will produce a more variable connection speed, that will decrease the further you are from the WiFi access point. In the graphic below, this download was achieved on the same computer and network but using a WIFI connection. The connection speed is a lot lower, and, as can be seen with the peaks and troughs, the connection is extremely variable.
Testing connection speed
It is important to thoroughly test any connection before introducing a telehealth service. This should be done at different times of day and over several days. Completing a speed test is simple using a website such as www.speedtest.net.
Private networks are restricted to specific users – for example, a hospital or a wider DHB network. Part of a public network may also be restricted for an individual or organisation, this is called a Virtual Private Network (VPN).
A private network is controlled, meaning connection speeds for telehealth are more predictable and reliable. However, if you need to have a telehealth session with someone outside the private network, connection speeds will be less reliable.
Connected Health is a network governed by the Ministry of Health and was established for the safe sharing of health information. It is a standards-based, commercial model for the delivery of universal connectivity across the New Zealand health sector. Registered users must connect to the network via a certified supplier.
The cost of using this network will generally be determined by the connection speed required. Connected Health is evolving as the central network for many larger health organisations' telehealth setup.
The three main managed network providers for health-related video conferencing are Dimension Data, Spark Digital and Vivid Solutions. Other commercial providers are also able to provide private networks and this number is expected to grow over time.
Hardware and software continue to evolve and faster networks are becoming more readily available. This evolution, combined with decreasing costs, positions telehealth for rapid growth over the next few years. Below is an introduction to some emerging technologies which will further support this growth.
H.265 video encoding
Video must be encoded before it is transmitted, and then decoded when it is received. This process is most commonly completed by a CODEC (code and decode) using the H.264 video compression standard. While this is an extremely efficient standard, a new standard H.265 has been developed which is said to double the compression ratio compared at the same level of video quality.
This will allow better videoconferencing sessions where there is limited bandwidth available – for example in rural and remote areas and also on mobile devices. Although it will take some time for hardware to support this new standard, so it can become widely available, it was demonstrated by Cisco in 2012 (see below and watch here: http://youtu.be/PZP75PEQo6E?t=49s).
VP9 video encoding
Another next generation CODEC is VP9, developed by Google. It has very similar performance improvements to the H.265 standard, but is a free, open source standard – unlike H.265.
It is unclear which standard will be most widely adopted – some manufacturers may support both standards.
Web real-time communication (WebRTC)
Currently, to place audio or video calls from a computer, users need to download proprietary software and create user accounts.
WebRTC is an emerging standard that enables web browsers to support browser-to-browser applications for voice calling, video chat, and file sharing without plugins. In the same way as web pages can have chat sessions initiated on web pages, WebRTC will enable audio and video calls to be made from the browser, with no additional software needing to be installed. At present this standard is supported by Chrome and Firefox, but not Internet Explorer or Safari.
For further information or specific answers to questions about networks, contact us at firstname.lastname@example.org.