It is a well-known fact that a small percentage of mobile data users use a disproportionate amount of network resources. In Europe, 6 percent of Vodafone subscribers generate 54 percent of traffic, while the 75 percent of lower-usage subscribers only account for 17 percent (Figure 1). In the US, the situation is comparable with 5 percent of users accounting for 68 percent of traffic, according to Sandvine (Figure 2).
It is equally well understood that wireless capacity is a finite resource that increasingly is insufficient to meet demand at the highest-traffic locations. Vodafone--which provides very valuable data on network utilization--recently stated that 7 percent of their base stations run at capacity, and presumably most are where traffic demand is highest and thus congestion affect a substantial percentage of their users.
At the locations where traffic demand exceeds supply, all subscribers suffer equally from congestion, but only the few of them that generate most of the traffic are responsible for that, if they all have equal access to the cellular network. This results in an unfair situation in which low-usage subscribers, who often pay just as much as heavy users, have access to a smaller portion of the key resources--i.e., capacity at peak hour.
Mobile operators understand this very well, and tools are available to manage traffic either to allocate network resources more evenly, if they want to keep the mobile broadband experience even among their subscribers, or to assign subscribers to different level of service, if the operator uses tiered services.
Most mobile operators prefer to delay the introduction of active traffic management to relieve congestion as much as possible because it is still unclear how subscribers will react to it. Even though traffic management benefits most subscribers, it can be seen as a big-brother intrusion from the mobile operator. At the current rate of data traffic increase, mobile operators cannot cope with congestion by simply adding a few base stations and have to resort to monitor and manage traffic, and to encourage off-peak or Wi-Fi usage (e.g., in the UK, Orange offers additional allowances for non-peak hour traffic from midnight to 4:00pm, and unlimited use of Wi-Fi hotspots.)
What do subscribers know about how their traffic is managed? Are they all treated equally, or do mobile operators try to balance network resources among subscribers? If so, how? Disclosure on how traffic is handled is usually--and understandably--kept confidential by mobile operators, but, in this case, shouldn't the subscribers benefit from knowing what the tradeoffs are (e.g., they could limit their data usage to avoid throttling, if this is something that may happen to them)? Also, couldn't the operators use their network management strategy as a differentiator from the competition?
To address these questions, I looked at what some mobile operators disclose on their websites--I did not talk to operators directly or use any knowledge from work on these topics--driven by the recent disclosure by Verizon Wireless as to how it manages traffic from the top 5 percent of their subscribers by data traffic volume.
Verizon's statement goes straight to the problem, with clarity and detail--in fact, maybe too much detail for most subscribers, but the information is there for those who want it. It is worth citing from the Terms and Conditions (T&C):
"We are implementing optimization and transcoding technologies in our network to transmit data files in a more efficient manner to allow available network capacity to benefit the greatest number of users. These techniques include caching less data, using less capacity, and sizing the video more appropriately for the device. The optimization process is agnostic to the content itself and to the website that provides it. While we invest much effort to avoid changing text, image, and video files in the compression process and while any change to the file is likely to be indiscernible, the optimization process may minimally impact the appearance of the file as displayed on your device. [...]
"If you use an extraordinary amount of data and fall within the top 5% of Verizon Wireless data users we may reduce your data throughput speeds periodically for the remainder of your then current and immediately following billing cycle to ensure high quality network performance for other users at locations and times of peak demand."
Further information as to how the optimization and transcoding technologies operate is available here. While Verizon Wireless describes in detail the tools used, they still does not provide much information on the circumstances in which they plan to use them.
Do other operators in the U.S. or elsewhere provide comparable disclosure on how they manage data traffic--or whether they do use traffic management tools at all? Not surprisingly, it turns out that the subscribers generally have very little information on how the mobile operators handle the traffic, although the level of disclosure is increasing.
In the U.S., most mobile operators do not provide any specific information on their websites and their T&Cs are typically vague enough to include pretty much any action from the operator. Virgin Mobile, for instance, states: "We may place restrictions on accessing certain Content, impose separate charges, limit the amount of data you can access or transfer, or otherwise limit or terminate services." T-Mobile provides a bit more information on its website because it offers an unlimited data plan with speed reduced after the subscriber crosses the 5 GB threshold:
"To provide a good experience for the majority of our customers and minimize capacity issues and degradation in network performance, we may take measures including temporarily reducing data throughput for a subset of customers who use a disproportionate amount of bandwidth. If your total usage exceeds 5GB ... during a billing cycle, we may reduce your data speed for the remainder of that billing cycle."
In Europe, there is an overall higher level of disclosure. Vodafone UK, for instance, acknowledges that it uses application-aware tools: "If your usage is excessively high, we will get in touch to discuss how you can reduce your usage - for example disabling peer to peer or other high bandwidth applications. If your usage continues to be excessive, we may limit the speed of your service to reduce your impact on other users, charge you for excess usage or terminate your account." Also, Vodafone UK details its fair-usage policy, which varies depending of the type of service plan (i.e., for some plans the fair-usage policy is enforced only after a traffic threshold is crossed.)
Italian operators Vodafone and Telecom Italia specify the action taken during congestion. Vodafone limits individual connections to 64 kbps in the downstream, and 64 kbps in the upstream. Telecom Italia throttles subscribers that are beyond the 1 GB traffic usage during the billing cycle to 128 kbps downstream and 64 kbps upstream from 5:00pm to midnight when needed.
The most user-friendly notice I have seen comes from 3UK:
"We carefully manage the traffic on our Mobile Broadband network so that everyone has a fair share of the service. So in an area with a particularly high number of people using the internet (and during busy times like 6pm to midnight) we may manage the speed of things like file sharing, software updates and some download activity which can slow down our service. This activity might feel slower than usual during these times. The majority of our customers, who are simply browsing the internet, won't be affected."
Verizon Wireless has set a good model for the industry to follow, along with some of the simple, but easy to understand messages that European operators have started to include in their websites, possibly due to the higher level of competition in their wireless domestic markets. The trend towards greater disclosure is welcome--and possibly an unavoidable one in the long term given the challenging increases in data traffic and consequent need for mobile operators to manage traffic more tightly. Clear and detailed information on how mobile operators manage traffic during peak hours will benefit both subscribers--who will be able to understand and better manage their data usage--and mobile operators--which can show how they optimize the use of network resources for the benefit of their subscribers.
Monica Paolini, Ph.D., is the founder and president of Senza Fili Consulting and can be contacted at [email protected] Senza Fili Consulting provides expert advisory services on wireless data technologies and services.