ADSL2/2+ INP

I have been told that with ADSL2 there is a thing called Impulse Noise Protecion.

I have a ST585v6, what i want to know is how can i see if this is on and if it is how can i turn it off?

At ieee

"Summary: Impulse noise in multicarrier communication systems behaves effectively as a modulating signal that controls the first moment of the background Gaussian noise. The composite noise, which is the aggregate of the Gaussian noise and impulse noise, has a probability density function that is conditionally Gaussian with non-zero average, hence referred to as biased-Gaussian. The BER-equivalent power of the composite noise source is defined as the power of a pure Gaussian noise source that yields the same bit-error rate (BER). The BER-equivalent noise for a biased-Gaussian noise is simply the amplified version of the underlying Gaussian noise source. The amplification factor is derived from the characteristics of the impulse interference. Any bit-loading algorithm designed for Gaussian noise sources is also applicable to biased-Gaussian noise sources provided that the BER-equivalent SNR is used in place of the measured SNR."

Says it all really.

sounds like time to download and read the CLI manual.

It's usually implemented at the DSLAM and not something that can be enabled / disabled on the router
My DG838GT shows the INP as being 2.0 - not sure if it displays on the Speedtouches - don't remember seeing it anywhere on the 780WL at least

I've never heard of INP before, and frankly I do not understand the ieee explanation. Is it a useful feature?

been there done that and found nothing

the 2Wire looks to have some reference to INP on G.dmt too.

Googling around I found "A significant portion of the end-to-end delay in high-rate DSL systems is due to the impulse noise protection scheme employed in order to shield those systems against random, non-stationary noise bursts of high energy that appear on the copper lines. Systems are protected from impulse noise using a combination of interleaving and Reed-Solomon codes. In order to lower the end-to-end delay without reducing the data rate that is available to the user, one needs to decrease the interleaver depth. This paper presents a way to achieve this reduction without compromising neither the robustness to noise bursts nor the data rate of the system. The proposed algorithm relies on the inner code used by many DSL systems and uses the metric provided by the inner code decoder at the receiver."

I've certainly seen Reed-Solomon options on some modems.

A Billion router mentions INP http://www.billion.uk.com/product/wireless/7402gl.htm even has an icon for it !

Reed Solomon is the algorithm used to correct corrupted interleaved ADSL data packets (as also used on CDs).

Hi

I think INP is just another form of interleaving, or works along side it by changing how interleaving works.

Broadcom chips in today's routers work with all values of INP as I think originally it was Broadcom that bettered how INP works and got an extension to the ADSL spec. Other modem chips may not work with the higher INP values (above 1).

On BE turning of interleaving also turns of INP, the two go hand in hand.

I'm not sure but I think the better version of INP is more intelligent and automatically varies the interleaving depth in order to reduce latency when a line doesn't require huge amounts of it. I could see this happening by the interleaving depth varying on each sync when I had INP2 and interleaving on BE.

Regards

Phil

Thanks for that. I couldn't understand the ieee explanation.