Nortel Networks DCT1900 Base Station Planning, Total Area Coverage, Absorption and Reflection

Technical Product Manual - DCT1900

Configuration Directions, Base Station Planning

CHAPTER 3

Base Station Planning

The major task in configuring a DCT1900 system is defining the number of Base Stations required to cover an area to a satisfactory level. This Chapter describes how a Base Station plan can be made in order to gain full area coverage. Chapter 5, Paragraph 5.2 explains how traffic requirements additionally influence the number of Base Stations.

Another aspect of Base Station configuration is powering of Base Stations. The various ways of distributing power to the Base Stations and the requirements on the power supply are described in Chapter 4.

3.1Introduction

The radio environment or the cell that is covered by a Base Station is not a spherical shape as often suggested in drawings. If a snapshot could be taken of the cell, it would become clear that its shape is more of a cloud form. The momentary size and shape vary depending on the material of which walls and floors are made of, the position and material of furniture, machines, air– conditioning and the position of the Base Station in such an environment. Because of these unpredictable conditions it is not possible to give any hard rules for calculating the number of Base Stations in a given situation.

Base Station planning is not very difficult. However, size, architecture and the structure of buildings and their influence on the RF field pattern cannot be foreseen. The quickest and simplest way to do the Base Station Plan is by measuring. During a site survey, an average cell size can be determined, with the help of a Site Survey Tool. This forms the basis of Base Station planning. Experience is the best guide in making a Base Station plan.

The guide–lines listed below will help give a better view on the local situation when the placement of Base Stations is being planned. Paragraph 3.6 explains how a site survey can be done.

3.2Total Area Coverage

zThe in–house cell size in offices may be in a range of 30-200 ft. radius; see Figure 3–1.

zThe cell size in exhibition halls or production halls may go up to a 660 ft. radius when there is enough free space for radio signals to travel.

zThe cell size outdoors in free space may be up to 1000+ ft. radius.

zBase Stations should not be placed near the outer walls of the building as this reduces the effective coverage area, except of course when a parking area, for example, has to be covered.

zBase Stations may partially cover the floors immediately above and below as well. The useful range through floors and ceiling varies between a 0 and 26 ft. (2 floors) radius; see Figure 3–1.

3.3Absorption and Reflection

zThe cell size depends on the materials used in walls, ceilings and floors.

zPlain, light or reinforced concrete, wood and plaster all absorb and pass radio waves in different ways.

zMetal walls and large metal cabinet rows reflect all signals, resulting in greatly reduced coverage behind these areas.

Config-DCT1900/R8/mw	3-1
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