What a Mesh!

Wireless meshing is nothing new. 

A wireless LAN mesh is made up of a group of cooperating APs, only some of which are directly attached to an Ethernet - the rest are merely plugged into a power source.

The APs form a wireless topology to route client traffic between any member of the mesh and the wired network. Ideally, a mesh WLAN is self-forming, self-optimizing and self healing, much like a router network; but unlike a router network, mesh WLANs must cope with two uniquely challenging variables - interference and media sharing - that have largely contributed to its uncertain viability in the enterprise.

While the concept is quite appealing for many environments like hotels, schools, warehouses, airports and public access areas, poor performance, complexity and reliability have made meshing a non-starter in the enterprise. 

A packet consumes bandwidth at every hop on a mesh path. Because Wi-Fi is a shared medium, it creates a delay for other clients and backhaul connections contending for bandwidth in the same frequency channel. Multiplied by the number of hops the packet must traverse within the contention domain, this depletion of capacity greatly limits the scale of the mesh WLAN.

Regardless of meshing, enterprises have been frustrated with the limited range and unpredictable performance of WLANs. Meshing only compounds the problem - more APs are involved in completing a client transmission, more traffic competes for wireless bandwidth and there is higher exposure to the possibility of interference. 

A new approach, dubbed SmartMesh, looks to overcome this crap. SmartMesh combined directional beam steering and forming with 802.11n to provide 300Mbps of access and backhaul capacity.  Backwards compatible with existing Wi-Fi clients, a 802.11n SmartMesh reduces the packet delay per mesh hop by as much as FIVE times over an equivalent 802.11g/a mesh, and a three fold increase in UDP measured throughput at two hops away from the root AP.

Moreover, the directionality of the embedded Smart antenna array gives SmartMesh APs 50% more range (at a given throughput) over conventional 802.11n APs so fewer of them are required to cover a given area.   This in turn reduces hop count and backhaul traffic load, further enhancing systems performance.

Confronted with interference, conventional APs either drop packets or respond by lowering the transmit data rate which reduces system throughput.  Smart Wi-Fi selects a signal path that avoids the interference, thereby preventing packet loss and preserving the higher transmit rate. Should it fail to find a quality signal path, auto-topology software in the downstream SmartMesh APs will reroute their wireless backhauls automatically when they detect a drastic decrease in the potential performance of the AP in trouble.

Detection algorithms that rely on SNR (Signal to Noise Ratio) statistics reported by the Wi-Fi chipset are often flawed because most chipsets cannot distinguish nearby interference, a simultaneous transmission by a client at close range to another AP, for example, from a strong signal.  Even when a mesh AP senses the interference, its response, such as re-routing or changing of the power and channel settings, typically requires actions on multiple nodes.  By the time the network converges, the interference may have transpired.   In the worst case, this can lead to “flapping” which de-stabilizes the mesh. 

Ultimately, by combining 802.11 with intelligent RF controls, Wi-Fi meshing can fundamentally change the traditional economics of wireless LAN deployment - reducing the cost of a WLAN by 50 percent, slashing deployment time by 50 percent while delivering three times the performance of a conventional 802.11g WLAN.

Now that's interesting!