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Home Networking - Wi-Fi Evaluation

Introduction

These pages describe the tests we have conducted in our home of many generations of "Wi-Fi" wireless networking products, starting in 2000 with the original 802.11 equipment. We wanted to develop a sense for how these products work in a real home -- especially to estimate the throughput users can expect through the walls and floors of their homes. Higher speeds will become especially important as wireless networking is used to carry video as well as data and voice throughout the home.

We have published the results of three rounds of formal product tests:

• Round One (early 2003): draft 802.11g access points with 802.11g and 802.11b notebook adaptors at 19 locations
• Round Two (early 2004): 802.11a, 802.11g and 802.11b access points and notebook adaptors at a single location
• Round Three (early 2005): 802.11g and early MIMO access points and notebook adaptors at 19 locations

Our overall conclusion is that the improvement during this period—with respect to both throughput and range—has been spectacular. Short-range throughput has improved from about 1 Mbps to nearly 40 Mbps. While many locations in our house received no signal at all with earlier equipment, we now get a workable signal everywhere—and with MIMO, very good throughput as well.

With these latest improvements, especially the advent of MIMO technology, wireless video networking is on the horizon.

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Round One

Between February and June 2003, we tested then-current Wi-Fi equipment. We wanted to see how well Wi-Fi worked in our home, how it compared with powerline networking, and to what extent the faster versions of Wi-Fi would be suitable for "whole home" networking including video.

We tested two Wi-Fi access points and three notebook adapters in our home the same way we had tested HomePlug earlier. We measured range and speed for the 11b and 11g versions of Wi-Fi at nineteen locations in and around our home (seven shown on the diagram on the right, and all on the test locations page). At the time of our tests, the 802.11g standard had just been approved, and all the tested devices were based on preliminary drafts of the standard.

In summary:

• 802.11g and 802.11b worked at all nineteen locations we tested, a substant improvement over first-generation 802.11b equipment.
• The measured file transfer speed of 802.11g averaged a little more than twice as fast as 802.11b.
• 802.11g speeds varied considerably more than those of 802.11b.
• These early implementations of 11g would not provide satisfactory video networking in many houses.

These tests are summarized in "Wireless Is Magic" -- Our Evaluation of 802.11g Wi-Fi (BBHR June 17, 2003) and described in detail in the following web pages.

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Round Two

In February 2004, we followed up with a more extensive series of tests to compare the throughput of products based on the 802.11b and 802.11g standards, and to see if 11g products performed better than they had in Round One. Many older products had been upgraded to full compliance with the 802.11g standard; lots of new 802.11g products had come to the market, some with Wi-Fi certification. We also performed a few tests of 802.11a, which had also started reaching the consumer market.

To establish a "baseline" measurement for further tests, we measured maximum throughput with the notebook adapter close to the access point in the same room.

These tests covered all three flavors of 802.11. They included five access points (802.11b, 802.11g/b and 802.11a/b) and six notebook adapters (802.11b, 802.11g/b, 802.11a/b and 802.11a/g/b)1.

These tests are summarized in Wi-Fi Evaluation Round Two (BBHR February 16, 2004) and covered in detail in the Round Two Wi-Fi Baseline Tests pages in this section of our web site.

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Round Three

In January through March 2005, we completed the 802.11g testing we had started almost a year earlier. By this time, early MIMO technology had appeared on the market. MIMO will form the tchnological basis for 802.11n--the next generation of Wi-Fi. While some of these MIMO products are marketed as "Wireless Pre-N", they are really MIMO extensions of 802.11g. We decided to extend the test to compare the performance of MIMO/11g with "standard" 11g. See MIMO/802.11n -- An Interview with Airgo (BBHR 2/24/2005) for more about MIMO and 802.11n.

Since vendors claim MIMO improves both throughput and range, we measured throughput at each of 19 locations in our house, examining how the maximum throughput is degraded by distance, walls, floors and other obstacles. This was a rerun of our Round One tests with updated and newer equipment.

The Belkin Wireless Pre-N Router looks very distinctive, with three antennas pointing straight up in front. These antennas, and the digital signal processing inside the box, are what differentiate MIMO from standard "diversity" antennas.

Here's a summary of what we found:

• MIMO/11g showed impressive improvement in both throughput and range over standard 11g.
• Standard 802.11g showed considerable throughput improvement over our earlier 11g tests.
• Combining MIMO/11g with standard 11g worked but gave mixed results.
• For the first time in our Wi-Fi testing, we feel that wireless video networking is on the horizon.

These tests are summarized in Wi-Fi's Leap Forward: Adding MIMO To The Mix (BBHR March 10, 2005) and covered in detail in the Round Three Wi-Fi Tests pages in this section of our web site.

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Web Pages

The following web pages provide a context for the summarized reports, describe the equipment we tested and our test procedures, and report our test results and conclusions:

• Wi-Fi Standards describes the primary standards—802.11b, 802.11g and 802.11a—and the new ancillary standards for security and QoS known as WPA and WMM. It also describes the emerging 802.11n standard and MIMO technology.
• Wi-Fi Context discusses the many variables in Wi-Fi performance, and what we did to attempt to manage these variables throughout our testing.
• Wi-Fi Products Tested describes the products we tested: wireless access points and notebook adapters from five different companies.
• Wi-Fi Test Procedure describes our testing procedures. The test locations page shows each location where we made test measurements.
• Wi-Fi Test Results: Round One reports the results of our Round One tests including our measurements of network speed for each combination of access point and notebook adapter at each location.
• Wi-Fi Conclusions presents our conclusions from Round One.
• Round Two Wi-Fi Baseline Tests reports the results of our baseline tests from Round Two.
• Round Three Wi-Fi Tests reports the results of our most recent Round Three tests including our new measurements of network speed for each combination of access point and notebook adapter at each location.
• HONEST: HOme NEtworking Speed Test describes and provides the source code for the program we wrote to evaluate and compare the performance of Wi-Fi and other home networking technologies. We have published the source code of the program as a service to the broadband home community. (We used an updated version of this program for our later tests, and expect to post the updated version soon.)

Thanks to

• Airgo Networks, Buffalo Technology, Linksys and SMC Networks for providing access points and notebook adapters to test
• AirMagnet for providing the AirMagnet Laptop software
• Symbol Technologies for providing 802.11 and 802.11b access points and notebook adaptors for several years

( www.airgowireless.com ) ( www.buffalotech.com/wireless ) ( www.linksys.com ) ( www.smc.com ) ( www.airmagnet.com ) ( www.symbol.com )

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