Sum distance, Product distance and Euclidean Distance

[Alam88]

Hi
As euclidean distance between two points is sqrt((x2-x1)^2+(y2-y1)^2 ) i.e distance between two points.
What is "product distance" and "sum distance" ? what these terms means and how to calculate product distance of a QAM constellation?

Thanks

 

[D.A.(Tony)Stewart]

I recall these terms are used different channel models for different fading types from self interference or multipath or Ricean or Raleigh, or block type low SNR channels, so that redundancy and forward error correction can be optimized for maximum code space distance of unexpected xy values are balanced or optimized with consecutive symbols distance. Of course the Euclid term is a product-sum, or matrix determinant types for longer patterns of consecutive codes.

More research required to specify requirements such as various Trellis Code implementations.