Editor’s note: The following comes from the executive summary of the “Measuring Broadband America” report issued Tuesday by the FCC. (Read the news story here.)
Based on the foregoing, the major findings of this study include the following:
Actual versus advertised speeds.
For most participating broadband providers, actual download speeds are substantially closer to advertised speeds than was found in data from early 2009 and discussed in a subsequent FCC white paper, though performance can vary significantly by technology and specific provider.
Sustained download speeds.
The average actual sustained download speed during the peak period was calculated as a percentage of the ISP’s advertised speed. This calculation was done for different speed tiers offered by each ISP.
- Results by technology
On average, during peak periods DSL-based services delivered download speeds that were 82 percent of advertised speeds, cable-based services delivered 93 percent of advertised speeds, and fiber-to-the-home services delivered 114 percent of advertised speeds.
Peak period speeds decreased from 24-hour average speeds by .4 percent for fiber-to-the-home services, 5.5 percent for DSL-based services, and 7.3 percent for cable-based services.
- Results by ISP
Peak period download speeds varied from a high of 114 percent of advertised speed to a low of 54 percent of advertised speed.
Only three ISPs had speed decreases of 10 percent or greater during the peak period (as compared to 24-hour average speeds).
Sustained upload speeds.
Peak period performance results for upload speeds were similar to or better than those for download speeds.
Upload speeds were not significantly affected during peak periods, showing an average decrease of only 0.7 percent from the 24-hour average speed.
Results by technology: On average, DSL-based services delivered 95 percent of advertised upload speeds, cable-based services delivered 108 percent, and fiber-to-the-home services delivered 112 percent.
Results by ISP: Upload speeds among ISPs ranged from a low of 85 percent of advertised speed to a high of 125 percent of advertised speed.
Latency is the time it takes for a packet of data to travel from one designated point to another in a network. Since many communication protocols depend upon an acknowledgement that packets were received successfully, or otherwise involve transmission of data packets back and forth along a path in the network, latency is often measured by round-trip time. Round-trip time is the time it takes a packet to travel from one end point to another, and for an acknowledgement of successful transit to be received back. In our tests, latency is defined as the round-trip time from the consumer’s home to the closest server used for speed measurement within the provider’s network.
During peak periods, latency increased across all technologies by 6.5 percent, which represents a modest drop in performance.
- Results by technology
Latency was lowest in fiber-to-the-home services, and this finding was true across all fiber-to-the-home speed tiers.
Fiber-to-the-home services provided 17 milliseconds (ms) round-trip latency on average, while cable-based services averaged 28 ms, and DSL-based services averaged 44 ms.
- Results by ISP
The highest average round-trip latency among ISPs was 75 ms, while the lowest average latency was 14 ms.
Effect of burst speed techniques
Some cable-based services offer burst speed techniques, marketed under names such as “PowerBoost,” which temporarily allocate more bandwidth to a consumer’s service. The effect of PowerBoost is temporary—it usually lasts less than 15 to 20 seconds—and may be reduced by other broadband activities occurring within the consumer household.
Burst speed is not equivalent to sustained speed. Sustained speed is a measure of longterm performance. Activities such as large file transfers, video streaming, and
video chat require the transfer of large amounts of information over long periods
of time. Sustained speed is a better measure of how well such activities may be
supported. However, other activities such as web browsing or gaming often
require the transfer of moderate amounts of information in a short interval of
time. For example, a transfer of a web page typically begins with a consumer
clicking on the page reference and ceases when the page is fully downloaded.
Such services may benefit from burst speed techniques, which for a period of
seconds will increase the transfer speed. The actual effect of burst speed depends
on a number of factors explained more fully below.
Burst speed techniques increased short-term download performance by as much as 52 percent during peak periods for some offerings, and as little as 6 percent for other offerings.
Web Browsing, Voice over Internet Protocol (VoIP), and Streaming Video
- Web browsing
In specific tests designed to mimic basic web browsing— accessing a series of web pages, but not streaming video or using video chat sites or applications—performance increased with higher speeds, but only up to about 10 Mbps. Latency and other factors limited performance at the highest speed tiers.
For these high speed tiers, consumers are unlikely to experience much if any improvement in basic web browsing from increased speed–i.e., moving from a 10 Mbps broadband offering to a 25 Mbps offering.
VoIP services, which can be used with a data rate as low as 100 kilobits per second (kbps) but require relatively low latency, were adequately supported by all of the service tiers discussed in this Report.
However, VoIP quality may suffer during times when household bandwidth is shared by other services. The VoIP measurements utilized for this Report were not designed to detect such effects.
- Streaming Video
Test results suggest that video streaming should work well across all technologies tested, provided that the consumer has selected a broadband service tier that matches the quality of streaming video desired. For example, standard video is currently commonly transmitted at speeds below 1 Mbps, while high quality streamed video
might require 2 Mbps or more. Consumers should understand the requirements of the streaming video they want to use and ensure that their chosen broadband service tier will meet those requirements, including when multiple members of a household simultaneously want to watch streaming video on separate devices.
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