Hands On Wireless Access Points
News IQ, a Carlsbad, Calif.-based laboratory, tested five different access points for VARBusiness. We looked at Actiontec Electronics' Wireless-Ready Cable/DSL Router R3010SUW, D-Link Systems' 2.4-GHz Wireless Broadband Router DI-713P, Siemens' SpeedStream 4-Port Wireless Cable/DSL Router SS2624, Linksys' Wireless Access Point Router with 4-PortSwitch BEFW11S4 v. 2 and Netgear's 11-Mbps Cable/DSL 802.11b Wireless Router MR314.
We tested the most important technical aspects of a wireless access point: radio-signal quality, data throughput and actual range of use.
Radio-signal quality is where it all begins. The better the signal quality, the longer the range of the access point. Signal quality is important for optimizing the transmit/receive signal-to-noise ratio (SNR) and for reducing radio frequency adjacent channel interference. Raising the SNR by transmitting a quality signal is essential for minimum data loss. The products were tested inside a radio-frequency isolation enclosure with a direct coaxial cable connection to an Agilent 89640a Vector Signal Analyzer to minimize radio frequency interference and radio frequency path losses.
Data throughput and switching speeds of the products are also critical and determine the ultimate perceived speeds of the units and how the access points perform under load. Those were tested with the Spirent Smart Bits SMB-600 and sent a constant-load data stream. Although it is rare to encounter a steady-state constant-load on a network device in the real world, measurement of steady-state constant-load performance may be useful in evaluating competing devices. Finally, range of use was tested using the Spirent TAS-4500 FLEX5 RF Channel Emulator. This test piece simulates real-world reflections from walls, moving the device around in an environment similar to what office users experience.
We were interested in comparing the performance of these products to a fixed 10 Base-T wired-Ethernet connection and measuring the throughput with different network packet sizes to see the difference. The smaller packet size allows us to observe how the products perform when they have more overhead to process the same amount of data, and can simulate conditions such as when these products are used for Web browsing or in interactive applications. We also measured the router-switching speed to determine how quickly the router performed the basic wired-router switching function.
For all of our over-the-air tests, we used the same PC-client configuration, based on Lucent Technologies' Orinoco PCMCIA Type II Extended PC Card with Orinoco Client Manager Diagnostic Wireless Link software and running Windows 2000 Professional. We also examined the performance of the various products at different data rates, since all of these access points can operate between 1 Mbps and 11 Mbps. All of the access points are able to adjust their data rates to maintain radio-channel integrity, and our tests measured how good each product was at making those rate adjustments.
Here's what our tests revealed.
1st Place: Siemens SpeedStream SS2624
This unit outperformed all the others in the wired RF signal clarity and range tests. This unit had the highest percentage of 11-Mbps delivery in the long-range test when the packet loss rate was factored in. While this unit had a single antenna, it was a solid performer: We measured a gain of approximately 4 dB to 6 dB compared with the only other single antenna unit,the Netgear MR314. Siemens offers a free, extended one-year warranty for a total of two years by simply signing up on its Web site. The unit has four switched-Ethernet ports, along with support for a print server.
2nd Place: D-Link DI-713P
This unit came in second place in the long-range testing and third in the medium-range testing. It includes both bi-directional print-server support and serial DB-9 modem support. However, it only has three switched Ethernet ports.
The DI-713P has two diversity antennas for improved signal multipath performance and includes Reverse-SMA connectors so the antennas can be removed for testing or alternative configurations. The downloads of large files were consistent over time with low standard deviations, reflecting a stable Layer 1 and antenna system.
The quick start guide was helpful and the unit was up and running without encountering any problems. The users' manual was full of detail and well-written. The DI-713P supports 128-bit encryption, VPN support with PPTA, IPSec and L2TP protocols. Specific ports can be opened to support games and other Internet applications that require access through the firewall.
3rd Place: Netgear MR314
This unit has excellent throughput in the near-medium (<++500 feet) range, but suffers from low antenna gain and antenna directionality. The Netgear was never able to obtain service in the long-range test. The antenna pattern is directional toward the front of the unit and does not perform nearly as well as it could with an improved antenna system. The antenna pattern was not an attribute that was tested, but was observed in every effort to allow the unit to perform in the long-range test.
This unit has an excellent heavy-duty metal cabinet construction, but a limited Web-filtering capability with a timer and four switched-Ethernet ports. It comes with a strong five-year, parts-and-labor warranty and 24/7 customer support.
4th Place: Linksys BEFW11S4 v. 2
This unit had RF signal noise fluctuation on the transmit signal. The fluctuation is periodic and seems to average at around a 23-second period. The net results are that the SNR fluctuates periodically between 18 dB and 36 dB during the long-range test, and++/-1 dB during the near-range test. This fluctuation caused loss of link during the download test and Windows file-handling errors, and caused the download speed to vary more than any of the other units.
Setup was exceptionally simple, and the universal plug-and-play feature worked very well. As soon as the network was plugged in, the router configured the IP DHCP addressing almost immediately, and networked PCs did not have to reboot. This unit also has four switched-Ethernet ports.
Pictorials in the user guide show the antennas turned at a 45-degree angle, and it appears the photographer may have done this to lower them to fit into the picture. That could possibly lead someone to configure the antennas in this position, resulting in a loss of range.
5th Place: Actiontec
Actiontec was the overall worst performer in the "Signal Clarity" tests, exhibiting poor error vector magnitude. What the Actiontec lacks in signal quality, however, it makes up with signal power and antenna performance. It came in third in the long-range and fourth in the medium-range tests.