Bandwidth Needed to Work from Home

The pandemic made it clear that the millions of homes with no broadband or poor broadband were cut off from taking the office or the school home. But the pandemic also showed many additional millions of homes that their current ISP connection isn’t up to snuff for working or doing schoolwork from home. Families often found that multiple adults and students couldn’t share the bandwidth at the same time.

The simplest explanation for this is that homes were suddenly expected to connect to a school or work servers, use new services like Zoom, or make telemedicine connections to talk to doctors. These new requirements have significantly different bandwidth needs when a home’s big bandwidth need was watching multiple video streams at the same time.  Consider the following bandwidth needs listed by Zoom:

Zoom says that a home should have a 2 Mbps connection, both upload and download to sustain a Zoom session between just two people. The amount of download bandwidth increases with each person connected to the call, meaning Zoom recommends 6 Mbps download for a meeting with three other people.

Telemedicine connections tend to be even larger than this and also require the simultaneous use of both upload and download bandwidth. Connections to work and schools servers vary in size depending upon the specific software being used, but the VPNs from these connections are typically as large or larger than the requirements for the Zoom.

Straight math shows fairly large requirements if three or four people are trying to do make these same kinds of 2-way simultaneous connections at the same time. But houses are also using traditional bandwidth during the pandemic like watching video, gaming, web browsing, and downloading large work files.

The simplistic way to look at bandwidth needs is to add up the various uses. For instance, if four people in a home wanted to have a Zoom conversation with another person the home would need a simultaneous connection of 8 Mbps both up and down. But bandwidth use in a house is not that simple, and a lot of other factors contribute to the quality of bandwidth connections within a home. Consider all of the following:

  • WiFi Collisions. WiFi networks can be extremely inefficient when multiple people are trying to use the same WiFi channels at the same time. Today’s version of WiFi only has a few channels to choose from, and so the multiple connections on the WiFi network interfere with each other. It’s not unusual for the WiFi network to add a 20% to 30% overhead, meaning that collisions of WiFi signals effectively waste usable bandwidth. A lot of this problem is going to be fixed with WiFi 6 and 6 GHz bandwidth which together will add a lot of new channels inside the home.
  • Lack of Quality of Service (QoS). Home broadband networks don’t provide quality of service, which means that homes are unable to prioritize data streams. If you were able to prioritize a school connection, then any problems inside the network would affect other connections first and would maintain a steady connection to a school. Without QoS, a degraded bandwidth signal is likely to affect everybody using the Internet. This is easily demonstrated if somebody in a home tries to upload a giant data file while somebody else is using Zoom – the Zoom connection can easily drop temporarily below the needed bandwidth threshold and either freeze or drop the connection.
  • Share Neighborhood Bandwidth. Unfortunately, a home using DSL or cable modems doesn’t only have to worry about how other in the home are using the bandwidth, because these services used shared networks within neighborhoods, and as the demand needs for the whole neighborhood increase, the quality of the bandwidth available to everybody degrades.
  • Physical Issues. ISPs don’t want to talk about it, but events like drop wires swinging in the wind can affect a DSL or cable modem connection. Cable broadband networks are also susceptible to radio interference – your connection will get a little worse when your neighbor is operating a blender or microwave oven.
  • ISP Limitations. All bandwidth is not the same. For example, the upload bandwidth in a cable company network uses the worse spectrum inside the cable network – the part that is most susceptible to interference. This never mattered in the past when everybody cared about download bandwidth, but an interference-laden 10 Mbps upload stream is not going to deliver a reliable 10 Mbps connection. There are a half dozen similar limitations that ISPs never talk about that affect available bandwidth.

The average home experiencing problems when working at home during the pandemic is unlikely to be able to fully diagnose the reasons for the poor bandwidth. It is fairly obvious if you are having problems with having multiple zoom connections if the home upload speed isn’t fast enough to accommodate all of the connections. But beyond the lack of broadband capacity, it is not easy for a homeowner to understand any other local problems affecting their broadband experience. The easiest fix for home broadband problems is for an ISP to offer and deliver faster speed, since excess capacity can overcome many of the other problems that might be plaguing a given home.

How Much Bandwidth Does a Home Need?

cheetah-993774If there is any one question that I am asked the most it is this: how much bandwidth do customers really need? Of course, what most carriers are really asking me is how fast they should make their data products. It’s a very good question.

The glib answer is that every family is different. But it is possible to talk about the kind of bandwidth that various common activities require and to make some generalizations about the average home. You might recall this is what the FCC did back when they reset the definition of broadband at 25 Mbps download. They looked at expected broadband usage for homes of two, three and four people and used that as a way to justify increasing the definition of broadband.

Since video is now the largest use of data for most home that’s the natural place to start any calculation of needed bandwidth. The problem is that there is no standard size of a transmitted video and the size of a video stream is going to depend upon the compression techniques used by the company sending the signal. Rather than a standard size of a video stream there is instead a pretty wide range.

The speed at which an ISP might see video just got a lot more complicated to predict by Netflix. They have always tried to send an HD video at 5.6 Mbps. If the customer’s broadband connection was not good enough to support that speed, then Netflix cut the quality of the video stream and sent it at a much lower rate. Netflix announced that they are now going to be more dynamic in the way they size and send video. They will send high action HD video, for example, at a higher data rate than a low-action movie. They will also have more than one option for downsizing the video so that it doesn’t have to drop all the way to SD. This means a whole array of different speeds of video from Netflix.

While video is the primary way that households currently use bandwidth, you can’t ignore all of the other uses, most of which are growing quickly. For example, there is now a significant amount of data used automatically in the background without direction from the user. Programs update automatically or constantly communicate in both directions with the cloud. One big and growing use of household data is cellphone data offloading. People tend to forget that their cellphone on WiFi is busily using their home bandwidth. There is a lot of talk in the industry of migrating away from cellphone apps and running more cellphone programs directly in the cloud, and that will mean a significant increase in cellphone data usage.

It’s also important to recognize that the Internet is not perfect and that every bit that is sent to us doesn’t arrive perfectly the first time. Depending upon the quality of the connection with the ISPs at both end of a transmission, there can be anywhere from a few to a relatively large number of bits that must be sent multiple times to complete a file download. For example, it might really require 1.2 gigabits of bandwidth to download a gigabit file. One measure of this is latency, and while not a perfect predictor of the amount of re-sent bit packets, we know that the higher the latency the more packets that must be sent multiple times.

Another thing to consider is that you can’t use every bit of your Internet connection at one time. For example, if you have a 10 Mbps connection you can’t view two 5 Mbps video streams at the same time. This is due to what the industry calls overhead, which is the background processes that enable your device to communicate with the Internet. The amounts of overhead can vary, but it’s not usual to see 10% to 20% overheads in a home network – bandwidth that is used by your router and the ISP to communicate in the background or to provide buffers between different data streams. The more things you do at the same time, the greater the overhead becomes, which to engineers is called contention.

I’ve used my own home as an example before. We are two adults and a teen who don’t have traditional cable TV. We all have cellphones and we work and play using bandwidth a lot. There have been a few times when our Internet connection from Comcast slows down. We see that anytime that it hits about 25 Mbps that we start having trouble doing things if we are all trying to use the Internet. So for our household, for right now, 25 Mbps  seems to be our magic number. But that number constantly grows and I would expect our threshold to get higher month after month as more and more parts of our lives use the web.