Interference - Free architecture

The Language of Limitations

The Wireless LAN industry has developed an entire vocabulary to describe the limitations of traditional WLAN; edge users, co-channel interference, black holes, hand-off delay, jitter, hidden nodes, mixed mode impact.

The 802.11 standard presents an environment characterized by a severe scarcity of channels, client-centric portability (rather than mobility), and unreliable bandwidth due to the shared medium and fair-access logic. But the WLAN standard is not at issue. It’s the way it has traditionally been implemented.

The traditional cell-based WLAN topology, while suited for a data-centric, portability model, is fundamentally challenged with its inability to cope with the scarcity of channels, delay-plagued AP-to-AP handoffs, and unpredictability of net system bandwidth, especially when multiple traffic types (voice and data) are introduced. The net result is a system that requires the designer to make a series of trade-offs between coverage, capacity, mobility, and security. And these trade-offs will only get worse in an era of 802.11n.

But trade-offs that might have been acceptable in data-only WLAN cannot be acceptable for a pervasive, multi-application wireless deployment.

Design Trade-Offs from Cell-Based WLAN

The Language of Pervasive Infrastructure

Guaranteed performance. Seamless mobility and security. Easy to own and scale. Complete coverage and maximum capacity. These are just some of the words that describe the enterprise WLAN created by Extricom. While staying compliant with the 802.11 standard, the Extricom system eliminates every traditional trade-off by rethinking the way APs and channels are controlled and exploited. In other words, it’s about a smarter deployment of the 802.11 standard, powered by new technology.

How It Works

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, MAC 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 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.

Wire-like connectivity with 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 function of the TrueReuse functionality.

In summary, the Extricom solution eliminates the traditional performance limitations caused by RF cell planning, co-channel interference, edge users, rate adaptation, mixed b/g devices, and frequent AP-to-AP handoffs. With that, a new language of wireless business value is born.

G4 Networks