Wireless

Cisco Wireless Controllers can be organised into mobility groups to help with intercontroller roaming. If there are two controllers that are assigned to the same mobility group, clients will be able to quickly roam between them. Layer 2 and Layer 3 roaming is supported for Mobility Groups along with the assistance technologies for roaming: CCKM,…

Larger wireless networks may be supported by more than one wireless controller with access points distributed across them Clients can roam from one access point to another, but they may also roam from one controller to another dependant on the access point. Layer 2 Roaming When a client moves from one controller to another when…

Wireless access points are bound to a wireless controller in a Cisco wireless network. When a client roams between access points in a Cisco wireless controller network, it is not the access point that handles the roaming but the controller due to it’s split-MAC architecture. In a Cisco controller network not much changes when the…

A client can move between one basic service set and another by roaming between access points. The client continuously checks the connection quality to the wireless access point that is connected too. If the signal degrades too much, the client will search for a new access point to roam too that can offer a better…

A directional antenna has a higher gain than an omnidirectional antenna as they focus the radio frequency energy in a particular direction. A typical use for a directional antenna is down long highways or in the aisle of a warehouse. Directional antennas can be used outdoors for areas away from a building or to cover…

An omnidirectional antenna is one of two types of commonly available antennas for wireless devices. The omnidirectional antenna is normally made up of the shape of a cylinder. It usually tries to propagate a signal equally in all directions from the cylinder, resulting in a donut shape pattern that extended further in the H-plane rather…

When an alternating current is applied to an antenna, a wave is produced. The electromagnetic wave will leave the antenna in a certain orientation. A length of wire pointing upwards will produce a wave that oscillates up and down in a vertical direction as it moves through free space. Other types of antennas may move…

Beam width of an antenna gives an idea of the antennas focus. Beamwidth is listed in degrees for both planes in a polar point graph. The beam width is calculated by finding the strongest point on a plot, somewhere on the outer circle. The plot is followed in either direction until the value decreases by…

Antennas are passive devices that do not utilise any external power or circuitry to boost the signal. They amplify or gain the signal by focusing the RF energy and how it is propagated into open space The gain of the antenna is a measure of how effectively it focuses the RF energy in a certain…

Antennas come in all shapes and sizes with their own gain values and intended purposes. Antenna gain is a comparison of an antenna against a isotropic (perfect) antenna is measured in dBi. The isotropic antenna does not actually exist, as a perfect antenna can not be physically made. To visualise an isotropic antenna it can…