Overshooting

you missed the most important 🙂

1. type of antenna (V aperture and H aperture, gain, backlobe)
2. height
3. tilt
4. power

The power is mostly used when it appears that you are covering the intended area with a very strong signal. There is no need to provide -60dBm in average in the cell, with -70dBm at the cell border.
By decrease the power by 10dB, you have -70dBm in average and -80dBm at cell border, which is acceptable. Of course, you must ensure the indoor coverage is not impacted (check TCH traffic after power reduction)

You can also decrease power of indoor sites, because you can’t play around with tilt or height. To avoid exposing surrounding people too much and to avoid overshooting outdoors.

Regards,

To be more clear….
the case being discussed here is of outdoor BTS sites. My vendor engineer(Nokia)has attenuated the power of BTS sites ranging from 4dB to 8dB. The cells(where power is attenuated) had poor indoor coverage.
The excuse given by Nokia is to prevent overshooting.
My theory is..if you are having overshooting then increase the tilt.And if the problem still persists then ask the vendor to reduce height. And this time he has no excuse as he is the one who has planned the height.
Prevention of overshooting at the cost of indoor coverage is NO.

Another point of view to consider…

Depending on your antennas it can be difficult to perform antenna tilting. If you do not have remote tilting on your antenna (even just remoted to the base of your cell site tower or base station equipment room) and you need to get an elevated platform/crane/cherry picker to the site to make the change, it can be expensive to do so. Motorised remote tilt makes such optimisation manipulations much easier (very important in a WCDMA or CDMA based network). You may if a situation is bad enough consider down powering a site as a short term measure until the antenna tilt can be changed – but typically that is only for short term situations.

Having said that, I still would not advocate for power reduction as an optimisation technique unless it was last resort.

Indeed there are instances where overshoot may be acceptable, particularly if you have to tollerate it to achieve your coverage objectives – but it is a careful tradeoff between how much overshoot to tolerate verses overall network performance. A balance needs to be struck and only sites covering areas where no other coverage can really be achieved any other way should be considered for up-tilting and hence acceptance of overshoot situations. If you are running a GSM network, it may be possible to work around an overshooting cell through careful frequency planning – leaving the cell it overshoots as an embedded cell operating on a different frequency. If it is a CDMA based network then that option most likely doesnt exist.

Hi,
Congestion, Interference …
Regards,

Hi,
cell with wide coverage could lead to sdcch and tch congestion because of big coverage, then sdcch assignment failure, sdcch drop, they all could be the consequencies of that. To much area covered, possibility to interfer and to be interfered is high. To far MSs may camp to that cell, so, possibility for sdcch congestion for MSs near the site, assignment failure for MSs far from the site etc. This is only my assumption, it depends from number of subscribers in the area, number of sites, frequencies etc.
Regards,

And some time you need to use power reduction to create a power balance of the TRXs at the same cell if dividing the cell TRXs between 2 combiners or duplexers when you have NO. of TRXs higher than the combiner capacity; 5, 6, 7 TRXs,

regards

Hi MKT,

Well definitely reducing power to avoid overshooting is not a preferable solution to the problem.
A step-wise approach need to be adapted to overcome this problem.

1. A slight tilt needs to be given to the RF antenna.

2. Thorough drives to be done at the cell coverage, especially at the border areas and check for interference.

3. If still problem exists and no further tilt can be given, then power optimization comes to picture.