User Manual

4 Introduction to the Extricom Wireless LAN System
The Extricom solution is based on a fully centralized WLAN architecture, in which the switch
makes all of the decisions for packet delivery on the wireless network. In this configuration, the
access points (APs) simply function as radios, with no software, storage capability, or IP address.
Even the basics of connecting are different: clients associate directly with the switch, not with the
AP. The AP acts as an “RF conduit” to rapidly funnel traffic between the clients and the switch. The
Extricom architecture has essentially centralized the 802.11 logic in the switch, while distributing
the wireless electronics in the APs.
Centralization of the Wi-Fi environment enables enterprises to deploy 802.11a/b/g/n channels at
every AP, creating multiple overlapping “Channel Blankets” that leverage each of the radios in the
multi-radio UltraThin AP. Each channel’s bandwidth is delivered across the blanket’s service area
(i.e. the combined coverage of all APs connected to the switch), with interference-free operation and
consistent capacity throughout.
As the client moves throughout the blanket, different APs will be in the best position to serve the
client at different times. The switch always uses the uplink and downlink path that is optimal to
serve the client. While this is going on “behind the scenes,” the client never experiences an AP-to-
AP handoff (i.e. de-association and re-association), resulting in seamless mobility.
Within each Channel Blanket, the switch avoids co-channel interference by permitting multiple APs
to simultaneously transmit on the same channel only if they won’t interfere with each other. This is
the essence of the TrueReuse™ functionality.
Extricom supports the 802.11n standard. 802.11n builds upon existing 802.11 standards. 802.11n
can be used in both the 5 GHz and 2.4 GHz frequency bands, introduces enhancements to the MAC
and the PHY layer, and makes use of multiple-input multiple-output (MIMO) technology. MIMO is
a technology that employs multiple transmitter and receiver antennas to support simultaneous data
streams. Such technology is capable of increasing data throughput via enhancements such as spatial
multiplexing (data streams), 40MHz channel bonding, Block Acknowledgment and frame
aggregation, and use of spatial diversity to increase range.
Features and Benefits
Extricom’s WLAN system solution offers the following features:
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 Ease of deployment - No cell planning
Extricom’s architecture requires no cell planning and experiences no constraints due to RF
interference or channelization. Consequently, Extricom APs can be deployed wherever needed,
in any density or even varying density, to meet the desired end-client service level (stipulated in
terms of connection rate). The traditional site survey is therefore reduced to just physical
equipment installation planning.
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 Multi-Layer WLAN
Using multiple radio Access Points, a single set of APs enables deployment of multiple high-
data-rate Channel Blankets with overlapping coverage, resulting in multiplied aggregate
capacity. Separate Channel Blankets also offer the unique ability to guarantee Quality of
Service by physically segregating different user types, traffic, and roles onto different channels.