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    what is zero forcing

    I am working on MIMO BC, can any body help me for following.

    What is Zero Forcing (ZF) in Wireless Communications?

    Arif Khan

    •   Alt20th March 2007, 03:12

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    zero forcing

    Hi Arif,

    ZF means when u have mutiple users and ur transmission is intended for one particular user and zero transmission (ideally) for others. But in practice there is interference for other users when u considering BC.

    I hopw this will help u.

    BR,
    Oz.


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    •   Alt20th March 2007, 03:14

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    Re: What is Zero Forcing (ZF) in Wireless Communications?

    ZF is just a detector, which has the property that it inverts the channel (which introduces cross-talking) and consequently from each user's perspective, there is on interference from others, namely forcing interference to zeros.

    Turn to MIMO BC, I knew A.Goldsmith from Stanford has series of paper on this topic.



    •   Alt29th March 2007, 05:19

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    Re: What is Zero Forcing (ZF) in Wireless Communications?

    The fundamental behind the zero forcing lies in the ZERO FORCING Filters used in Wireless communication.

    Zero forcing filters are used to minimize Inter Symbol Interference (ISI) to avoid cross talk between users. When the input pulses are not properly pulse shaped they may overlap with each other and this my result in ISI.

    Popular pulse shaping techniques are Raised cosine Pulse shaping, Gaussian Pulse shaping , Duo-binary pulse shaping etc...

    In Raised cosine pulse shaping the pulse shape attains zero at every multiples of 1/T (T=Bit Duration). So if another adjacent pulse with its maximum is made to sit at this point then two pulses are sent with out much ISI.

    Normally there is some amount of noise at the zero point that will be added due to the channel. So the value at zero point is essentially not zero now . Zero forcing filters are used to make NULL the value at zero point there by introducing the possibility of sending another pulse with its maximum places at this point, thereby increasing the transmission rate.


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    Re: What is Zero Forcing (ZF) in Wireless Communications?

    the word zero forcing in communiction particularly digital communication means that u have an equilizer that takes an input signal comming from a distant place contaminated with noise and distortion and ir u process this signal without passing it through this equilizer ur system is not go no work , one of the many reasons is that the signal strength is deteriorated....so when we pass a digital signal through a zero forcing equilier it detects the zero crossing of the incomming signal and in this way get and information about the phase , frequency of the incomming signal...and if there is a regenerative repeater also after as is in digital communication it would use the information provided by zero forcing equilizer and generate new pulses


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