Uplink/Downlink Balance; Connecting Antennas To Remote Units - ZinWave UNITIVITY 5000 User Manual

UNItivity 5000
User Manual

7.2 Uplink/Downlink Balance

Care should be taken not to separate the two antennas by so much distance that the path difference
between Tx and Rx to the mobile affects system performance. Some services are more affected by
uplink/downlink path difference than others, especially those using high dynamic range mobile power-
control such as WCDMA.
There are two WCDMA system effects to be aware of when testing a separated antenna coverage
area:
•
When the mobile is close to the Tx antenna but some distance from the Rx antenna, the initial
call-setup power that the mobile transmits will be lower than expected by the BTS. It is likely
that the BTS will fail to receive the initial call-setup attempt, so the mobile will transmit again at
a higher power level. The mobile will continue to ramp up its power level until the BTS receives
and acknowledges the message. This effect can cause longer initial setup times close to the
Tx antenna and in extreme cases may cause the mobile to timeout during call setup. In order
to compensate for this effect, the balance of gain between uplink and downlink can be adjusted
to increase the uplink gain. This is usually done in the head-end by moving attenuation from
the uplink to downlink paths. However, in some case the UL/DL balance setting can also be
used within the UNItivity 5000 platform if the uplink gain is not already at maximum.
•
When the mobile is close to the Rx antenna but some distance from the Tx antenna, the initial
call-setup power that the mobile transmits will be higher than expected by the BTS. As long as
the mobile power does not overload either the Remote Unit or the BTS input then this should
not cause a call setup failure.
Note that the path difference between Tx and Rx at the edge-of-cell is likely to be much smaller than
near the antennas due to the effect of the indoor propagation conditions. Where there are no line-of-
sight differences between Tx and Rx the edge-of-cell path difference will be less than 3dB for most
services.

7.3 Connecting Antennas to Remote Units

The Remote Unit has separate connectors for transmit and receive antennas. The choice of antenna
depends on the RF coverage and planned designs for a building, you may need extension cables
depending in where the antennas are placed relative the Remote Unit.
To connect antennas to Remote Units:
1. Connect the N-type male connections into N-type female connectors on the top of the Remote
Unit. Note the markings on the unit for Rx and Tx.
2. If you have not already done so, feed the RF extension cables through from the Remote Unit
to the Antenna.
3. Connect the N-type female connections into N-type male connectors to the RF tails.
Pay attention to the mechanical stress placed on the connector if using large inflexible cable.
Use short flexible jumpers where appropriate.
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