Radio Coverage Properties; Radio Coverage Overlap - Nortel 7430 Deployment Manual

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3.0 Radio Coverage Properties

The deployment of Base Stations and Repeaters is a critical aspect of the Digital Mobility
solution. If the Digital Mobility Controller installation is to be successful, the deployment concepts
explained here must be followed.
To determine the permanent installation location of Base Stations within a given installation, a
deployment survey must be taken to discover the optimal location and total quantity of Base
Stations required for the installation.
It is extremely important to keep in mind that radio coverage is dependent on construction
materials, method of construction and environment. These factors will always be involved in
every installation. Therefore, it is not possible to relate one installation to another insofar as
number of Base Stations or positioning of Base Stations. Each site is relatively unique.
While an extensive guide to effective RF coverage planning is outside the scope of this manual,
the following points should be taken into consideration when planning the site, prior to installation.
•
The Deployment Base Station provides a typical coverage radius similar to that of a
regular Base Station and propagates in all directions.
•
Wireless handsets can move between coverage areas of different Base Stations while
receiving continuous service and maintaining conversations in progress.
•
For efficient handover of conversations between Base Stations, deploy multiple Bases
with sufficient overlap of coverage between them (i.e. plan for some areas to be covered
by more than one Base). Overlaps are necessary to allow handsets the time necessary
to handover to a Base from which a better signal quality is received.
•
Avoid placing Base Stations near other electronic equipment, large machinery, metal
constructions etc as the range can be severely affected.
•
Base Stations should be placed between 6- 12feet/1.8-3.6m in height on a wall or up to
30 feet/10m when suspended from a ceiling. If they are placed any lower, persons
walking around could interfere with the radio signal. Antennas should always be
mounted in a vertical orientation utilizing the supplied mounting bracket. Coverage area
can be adversely affected if the Base Stations is mounted improperly.

3.1 Radio Coverage Overlap

Other factors involved in a deployment relate to radio coverage overlap. A radio coverage
overlap is required between adjacent cells to allow for the handover of active conversations from
Base Station to Base Station or Repeater.
A coverage overlap occurs when the radio fields of multiple Base Stations overlap each other.
Base Stations must be placed in such a way that the radio coverage from one Base Station
to another overlaps by 30 to 45 feet/10-15m. An overlap is required so that as the handset
moves about the various coverage zones Base Stations have time to hand the call off to another
Base Station.
If the overlap area is not enough - less than 30 – 45 feet/10-15m there is a risk dropping the
connection while moving from one coverage area to another. However, too much overlap results
in a wasted coverage area.
In order to support the handover of calls from one base station to another, a maximum traveling
speed for the handset of 3mph (5km/h) is allowed relative to the size of the overlap.
NN40110-304 1.1