Psiber Data Systems RF3D manual Antennas

manual

Note that, in this cellular structure, channel overlap must be avoided not only within each floor of a building, but also between adjacent floors. In other words, access points above and below one another should not use the same channels.

Another important consideration is the security of a company-wide wireless network. Usually the operator wants to avoid WLAN transmission beyond the boundaries of the company’s premises in order to prevent unauthorized access from outside.Furthermore, in designing the network’s cellular structure,you should also consider what applications are to be transported over the network.If an application such as telephony is to be pro- vided over the WLAN,then each cell — that is,each access point — is usually supposed to support a specific number of simultaneous calls. This is usually not feasible in cells of the greatest possible size, so the network should be designed with smaller cells. Smaller cells can be achieved by reducing the transmitter power of specific access points. In this case, of course, more access points are required to cover a given area.

Another consideration in planning wireless cells is that the data rate depends in part on the signal power received at any given point. For applications with low data traffic, such as warehouse or logistics applications, it can be efficient to use the outer fringes of a cell in spite of weaker signal power.

2.4 Antennas

Antenna technology would take up a full chapter in a survey of WLAN fundamentals. For planning purposes, you need to know that cell shapes can be optimized by using appropriate antennas.In office floors,for example,signal radiation in a horizontal plane is very important, while vertical radiation is often undesirable, since it causes interfer- ence in the floors above and below. A highly directional antenna, such as a panel antenna, may be used to cover a long corridor.Yagi antennas have an even narrower beam and are used for point-to-point communications, such as radio links between two buildings.

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