Multi-link 802.11n wireless mesh

On February 10, 2010, Xirrus announced its multi-link 802.11n wireless mesh. The advent of the 802.11n standard has enabled unprecedented data capacity over Wi-Fi networks. Combining this with the unique, multi-radio architecture of the Xirrus XN Wi-Fi Arrays, a Wi-Fi mesh backbone can now be accomplished with a level of performance previously only possible with dedicated, expensive, point-to-point systems . . . or wire itself.

A Wireless Distribution System, or WDS, is a system that uses Wi-Fi to connect multiple Access Points together in a daisy chain or mesh configuration. In the past, Wi-Fi has not been very effective for deploying high performance WDS because of legacy Wi-Fi bandwidth limitations and the limited number of radios used in standard products. A traditional Access Point typically has only two radios, with one radio allocated to the WDS or a repeated mesh link and one radio servicing local Wi-Fi stations. There are several fundamental limitations with this design:

• A single 802.11n radio in the Access Point limits the wireless backbone link to a maximum 300Mbps data rate. This single radio's bandwidth is typically shared among multiple APs in a meshed fashion that significantly reduces the effective bandwidth even further.
• The second 802.11n radio remaining in the AP is used for station connectivity and must operate in only one of the two available Wi-Fi bands, 2.4GHz or 5GHz, limiting performance and flexibility of the network.
• A single radio backhaul link creates a bottleneck for all traffic and a single point of failure.
• The limitations mentioned above can be alleviated in part by dedicated wireless backbone / backhaul devices, but this means additional components and cost added to the network.

Xirrus has overcome these limitations with its enhanced WDS implementation in the 802.11n XN Wi-Fi Arrays. Up to 3 802.11n radios can be dedicated and aggregated into a single wireless link, and up to 4 such links can be created per Array. The radio density of Xirrus' new XN12 and XN16 Arrays provides the flexibility to create multiple wireless links in one device to create a Wi-Fi backbone as an element of an all wireless network, while at the same time servicing up to hundreds of 2.4GHz and 5GHz Wi-Fi clients - all in one device.

Key advantages of the XN Array for WDS include:

• Aggregation of up to 3 radios per WDS connection, providing near gigabit speeds of up to 900Mbps Wi-Fi bandwidth in a single link
• Up to 4 links per Array, each providing a dedicated mesh link with dedicated Wi-Fi bandwidth:
• The Xirrus Array uses multiple radios for backhaul capability, allowing full-duplex operation with traffic sent in both upstream and downstream directions simultaneously. This increases the performance, scalability, and reliability of the entire wireless network.
• The Xirrus Array uses multiple radios for backhaul capability to provide interference immunity. Unlike legacy APs where interference on a single channel (radio) can degrade or stop the link, Xirrus Arrays have multiple radios operating on different channels that allow for continuous robust operation even in the presence of interference.
• Internal high gain, directional antennas in the Array that can be directly used for WDS, or connections for external antennas an option.
• Both 2.4Ghz and 5Ghz bands can be serviced with multiple radios available for both frequencies.

Multi-radio 802.11n WDS is now available on all Xirrus XN Array models.