As wireless networking has proliferated homes and offices around the world, and network vendors keep releasing with new devices on a regular basis, you now have so many options that it's hard to make a choice. The truth of the matter is, regardless of how many things a wireless router or access point can do, the two most important things about them are their speed and their range. Our tests are designed to evaluate these variables.

Test environment

We test throughput and range in a multiple-node network environment consisting of a 3.4GHz Pentium 4 550-based desktop system and two Dell Precision M4300 laptops. All three computers run Windows XP professional. We typically test a router or an access point with a PC Card adapter from the same manufacturer; if no PC Card adapter is provided by the manufacturer, we use a Linksys WPC600N card. The reason this card is chosen is because it's one of a few that support all wireless specifications and both 5GHz and 2.4GHz wireless bands.

Before we conduct our performance tests, we analyze the local RF spectrum to confirm that the environment is conducive to wireless testing and to identify the ideal channels to use for the tests. We perform this analysis using an AirMagnet Spectrum Analyzer. We select channels based on the best available combination of minimal interference, minimal number of devices, and the least amount of utilization. Each of these three criteria also must meet minimal thresholds--we will not conduct testing if thresholds are exceeded. This ensures that we test every networking device under ideal conditions.

Configuration

Because 802.11b, 802.11g, 802.11n, HomeRF, and Bluetooth adapters, not to mention appliances such as microwave ovens and cordless phones, all operate in the same 2.4GHz spectrum (although some operate in the 5GHz spectrum), we test in an area free of any RF interference--to achieve maximum signal strength and reflect a best-case scenario. As signal strength fades, many devices negotiate with the clients to transmit at slower speeds. Generally, throughput speeds will decrease as range increases.

Range and throughput tests

CNET Labs performs its range and throughput tests in a real-world office environment; therefore, our tests do not represent range and throughput capabilities across all environments. You may get better results in an open-air environment, a spacious facility without walls, or the outdoors. An area such as ours, divided by numerous walls, leads to decreased range and throughput capabilities. Our tests, therefore, provide a benchmark for estimating the range and throughput of wireless networking devices in an indoor setting, with a relatively limited number of RF obstacles.

Our throughput tests involve timing the process of transmitting 500MB of data over the wireless connection to determine the throughput rates. The results are most of the time much lower than the theoretical ceiling of a wireless specification but, nonetheless, the actual sustained rate that you would get in real-world usage. Performance results for all throughput tests are reported in megabits per second (Mbps). We did three throughput tests:

• Maximum Throughput Test (aka "Throughput Test"): We place the wireless 15 feet away from the router with settings of both devices tuned to be in favor of the best possible transmission speed. For example, we set a Wireless-N product to run in Wireless-N only mode to minimize interference from legacy 802.11g devices.
• Range Throughput Test (aka "Range Test"): We place the wireless client 100 feet away from the router with the same settings.
• Mixed Mode Throughput Test (aka "Mixed Mode Test"): The wireless router is set to work in mixed mode, where it supports all wireless specification including Wireless-N (802.11n), Wireless-G (802.11g), and Wireless-b (802.11b). We connect a Wireless-N test client and another legacy Wireless-G client to the router. We place the test clients 15 feet away from the router.

In addition to throughput speed, we try to determine the best range of the router. For our maximum range tests, we gradually increase the distance between the client and the router in 25 foot intervals until we can no longer receive a signal. The result of the test is the last distance where we could maintain a steady signal.

During the testing process, we also look at issues including the amount of heat and noise a product generate, whether its signal is stable, and so on. This helps us provide a full picture of the product in question.