Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Power Control

Viewing 9 posts - 1 through 9 (of 9 total)
  • Author
  • #53669

    Hi all,

    What is the difference between DTX and Power Control.

    Both features works in DL + UL.

    How does the behaviour of BTS and MS differs to each other and with respect to self in case of DTX and PwrCtrl.

    Discussion is appreciated.



    DTX : in case no useful speech is to be sent on the radio interface, the burst(s) is (are) sent almost empty –> no speech = no usage of the radio resource. This radio resource cannot be used by someone else though. Only benefit is a lower usage of the frequency.

    Power control : in case the receiver measures a strong signal from the emitter, then the emitter decreases its TX Power.
    In case the receiver measures a weak signal, the emitter increases its TX Power (if possible).
    The goal is for the receiver to measure an average signal, because
    1) if the signal is too strong –> emitter might interfer with other emitted signals (high frequency usage = higher interference probability)
    2) if the signal is too weak, okay, it’s good to avoid interfering other signals, but the receiver might loose the connection.

    other benefits of PC and DTX : less battery consumption and less electromagnetic waves traveling in your brain.


    There is also a kind of relation between DTX and Power Control. DTX is, in a certain sense, a kind of PC: the “no speech” and “no data” frames (during the silent descriptor – SID) are transmitted (both on MS and BTS side) at idle power (minimum power) in order to reduce interference and save MS battery and reduce BTS power consumption.


    hello michelle,

    what do you mean by “idle power” ?
    As far as i know, the few bursts containing “comfort noise” that are transmitted while DTX is active are sent with standard tx power (as defined by power control algorithms), isn’t it ?

    the relation between PC and DTX, as you pointed out, is only the benefits of these features. They both serve the same purposes.


    Thanks for replies!

    One i.e. DTX works on the basis of presence/absence of speech.

    while the other PC works on the distance.

    Both effects the Tx Power of MS/BTS.

    DTX just reduces the power to a default/threshold while PC has a “range”.

    One thing i wonders if both these features have such a wide range of benefits then with what objective the vendor or standard have provided the options of ” Disable” for them.



    I’m not sure abt any situation where we need to disable DTX. But we may like to disable power control when we have severe interference issue. Lets say in an area you have very high external interference due to a jammer or something else and interference level suddenly increases. In this case you will like to transmit at maximum power always to achieve best possible C/I. Of course PC algorithm takes into account the quality but increasing the power in poor quality conditions still takes some time during which call can be dropped.


    Hi Pix,
    you make reference to SID frames (SID FIRST, SID UPDATE and SID ONSET, sent respectively at the beginning of silent period, refreshed every 8-9 frames, and at the end of the silent period) containing information about comfort noise. They are transmitted with the standard power commanded by PC algorithm. During the silence period however empty frames (NO DATA, NO SPEECH frames) are sent with a very low power, near to 0 dBm (on BTS side).

    I refer to Siemens BSS.



    Many thanks for the explanations, I never really dug into the DTX “inner” mechanism but now it seems much clearer.


    Please NEVER forget what i’m going to tell you :

    The power control does NOT take into account the distance. It is just based on RXLEV and RXQUAL. RxLev & RxQual are not correlated to the distance (just think about indoor coverage, or line of sight coverage).

    Pranay Sharma


    DTX is enabled from BSC and MSC side and same can be observed in BSC lever 3 traces. All RF related parameter is also enabled for DTX but in DT tool (TEMS) DTX is showing always 0 value (not working), kindly suggest.

    But AT BSL level trace in channel activation-Channel mode UL and DL DTX is showing working (DTX is applied).

    But at MS (DT TOOL) dtx is showing not working.

Viewing 9 posts - 1 through 9 (of 9 total)
  • The forum ‘Telecom Design’ is closed to new topics and replies.