4.6Link budget

In order to verify either quality or unavailability requirements, a link budget for each cell (or sector) has to be calculated on the basis of system features and propagation condition. In particular it is necessary to know the following parameters:

-receiver power threshold level;

-transmitter output power;

-feeder attenuation;

-cable attenuation;

-co-channel and adjacent channel sensitivity curve;

-propagation environment;

-antenna gains and RPEs.

4.6.1Quality requirements

Taking into account ITU-R recommendation F.697-2 [2], which is applicable to the local grade portion of an ISDN connection at a bit rate below the primary rate, requirements on error performance can be summarized as follows:

-the SESR should not exceed 0,015 % in any month;

-the ESR should not exceed 1,2 % of any month. Where:

-SESR represents the ratio between the SES (as defined in ITU-T Recommendation G.821 [3] and the overall number of measured seconds;

-ESR represents the ratio between the ES (as defined in ITU-T Recommendation G.821 [3] and the overall number of measured seconds.

It is worth noting that the SES requirement is equivalent to former requirement

(see ITU-R Recommendation F.697-1) [1] recommending that the BER should not exceed 10-3 for more than 0,015 % of any month with an integration time of 1 s. For this reason in the present document we will refer to the former requirement.

In order to verify the last requirements, a general expression for link budget calculation has to be considered:

ETSI