Diversity Repeaters

In addition to the centralized CellEnhancer solution, there may be ‘Dark Spots’ that lack much more in Ec/Io than several dB’s; these areas, once identified and ordered in a prioritized list, may be treated by adding High-Power Repeaters. The main benefit here is the intensified coverage due to shorter distances between the Repeater and the target coverage area, as well as free line-of-sight, resulting in low path-loss. In case of flat fading (due to reflections around the subscriber unit from short ranges) transmit and receive diversities provide additional improvement in performance.

The Repeaters pick up additional traffic (Erlangs) from the dark spot areas. The cell site in this case would support the extra Erlangs gained by the introduction of the Repeaters.

The convenient remote monitoring and control of these Repeaters introduces an important aspect for their successful operability and maintainability. It is crucial that the operator will be able to set the Repeater parameters optimally, or else he may degrade the base-station performance in an unacceptable way, or use inefficiently the Repeaters.

The drawing below demonstrates dark spot coverage in a Cell using three Repeaters. The Repeater installed in sector ? is a two-lobe repeater, the Repeater on the boarder of alpha and beta is high-power single lobe, and the Repeater in alpha is a single lobe low-power unit.

How to provide improved indoors coverage by Celletra Repeaters?

The Figure to the right presents a typical scenario where a base-station, that may be only several hundred meters away from a building with many users, does not penetrate the windows and/or walls at high enough levels, even if the street RSSI levels are quite good. By locating a Repeater across the street, with the donor BTS signal boosted by ~75dB, it is possible to raise the RSSI levels at the building by ~45dB.

Applying transmit and receive diversities (in one case by employing a single cross-polarized antenna, reduced fade margin and smoother indoor levels (by some 5dB) have been demonstrated.