Sector splitting

[snabeel03]

Guys,

Any idea what is sector splitting? Why it is useful?

[romagdinio]

Sector splitting is to add new sector to the site with the same SC of other sector in the same site (by adding a splitter to split the power between the two antennas of the sector). the splitting is useful to solve coverage problems as it is similar to adding a new sector.

[wireless.com]

Is very useful when you need to use antennas wall mounted (e.g. church towers) and, therefore, you need an extra antenna...

[Resistor]

Sector splitting is to add new sector to the site with the same SC of other sector in the same site (by adding a splitter to split the power between the two antennas of the sector). the splitting is useful to solve coverage problems as it is similar to adding a new sector.

While the above explanation is undoubtedly correct and accurate, in many cases people would use the term "Sector Splitting" in the place of "Cell Splitting", in which case it gets an entirely different meaning: it means that we split an existing sector on a given carrier, say currently with a 90- or 105-degree antenna, into two sectors, each with 45- or 60-degree antenna. This, naturally means that the two sectors are two separate cells with different PSC. The advantage gained is that using a narrower-beam antenna reduces the extra-cell interference and thus immediately increases the pole capacity in the uplink (Why? Because the narrower the antenna beam, the smaller portion of the horizon it covers and thus the smaller part of total available interference is received.) Using a narrower-beam antenna means that it will have higher gain, which immediately increases the power-limited capacity in the downlink (Why? Because with higher antenna gain the same TX power will result in higher RSCP and possibly even higher Ec/Io and Eb/No when the interference in Io and No is mainly extra-cell; this may require adding downtilt to prevent increasing the interference generated by the sectors in question to their neighbours).

Currently both in US and Europe the sector-splitting is one of the items on the operators menu, mainly done by using antennas, which integrate two 45-degree antennas into one box. The two antennas inside the box have azimuths of -23.5 and +23.5 degrees relative to the direction in which the box faces. Thus an existing 3-sector site is converted into a 6-sector site simply by replacing the existing antenna boxes and pulling up the tower a second set of feeders (the wind load of the tower remains almost the same, it looks like a 3-sector tower from outside, but has twice the number of feeders). The same approach works well when the site is on a building, but care is taken to avoid the two beams of the integrated antenna box to be deformed by being at a too close angle to the walls of the building.

There are advantages to be had when the antennas are not integrated into a single box, such as applying independent mechanical tilt. In cities, like those typical for US (think of Seattle, Boston, Chicago, Los Angeles, Atlanta or any city with skyscrapers) splitting sectors and using 6-sector sites allows to choose the sector azimuths and downtilts in such a way as to avoid specular reflections from skyscrapers (Why? Because with three 90-degree antennas on a site it may be difficult to choose the azimuths in such a way as to not point one of them to a nearby skyscraper, and reflections will be unavoidable. But with with six 45-degree antennas we can choose the azimuths in a such a way as to point only one of them to the nearby skyscraper and downtilt it significantly, or even reduce the CPICH power significantly for that sector.) For Europe this is less of a problem, since skyscrapers are relatively fewer, limited mainly to Docklands in London, La Defence in Paris, some newly-developed areas of Madrid, and such. So there the main motivation for sector-splitting is improved capacity and coverage in historic cities, where building new sites is very expensive due to conservation laws.

Resistor