D-Link's DWL-900AP+ wireless access point (AP) can increase 802.11b wireless LAN (WLAN) data transfer rates by about 20 percent when used with other D-Link products, such as the DWL-520+ PCI adapter and the DWL-659+ PC Card.

When installed as a wireless bridge with another 900AP+ device, data transfer rates can theoretically reach 11Mbit/s, according to D-Link. We could not reach this speed in IT Week Lab tests, however, though we did register a 7Mbit/s transfer rate between the PC/PCI cards and the access point - a 20 percent improvement in performance. The boost in throughput derives from an integral Texas Instruments chip which implements Packet Binary Convolutional Coding (PBCC), but can still communicate with standard 802.11b products when set to normal mode.

By implementing PBCC, along with Intersil's Complementary Code Keying-Orthogonal Frequency Division Multiplexing (CCK-OFDM), D-Link is anticipating the 802.11g specification, which is undergoing IEEE ratification. Both standards may be incorporated into the final 802.11g specification as optional modes.

We tested the access point by connecting it to a 3Com 4250T Fast Ethernet switch, installing the DWL-520+ PCI card in a standard desktop system and the DWL-650+ PC Card in a standard notebook PC, with both systems running Windows 2000.

Setting up the access point is simple and can be done through a JavaScript-enabled browser or D-Link's management tool, which also provides real-time indicators of signal strength, link quality and data transfer rate.

The test file was a 1GB .zip file, and the maximum transfer rates we obtained were 6.5Mbit/s from AP to PCI card; 7.0Mbit/s to the PC Card; and 6.8Mbit/s from PCI card to PC Card.

We also used a notebook PC equipped with a standard 802.11b Compaq W110 PC Card to transfer files. Transfer rates averaged about 5.0Mbit/s to the access point, 4.8Mbit/s to the PCI adapter, and 4.9Mbit/s to D-Link's PC Card. The D-Link card could also associate easily with our Compaq WL1510 enterprise access point. Enabling encryption resulted in slightly slower transfer rates.

The 900AP+ can operate in four modes: as an access point; as a wireless client, connected via a crossover cable to a PC; as an AP to-AP bridge; or as an AP-to-multi-point bridge.

To check the claim that throughput could almost double if D-Link products are used to create a bridged network, we set up a 900AP+ to bridge to another 900AP+. Using this setup we measured a maximum data transfer rate of 5Mbit/s between the two access points, nowhere near D-Link's claimed transfer rate of about 11Mbit/s.

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