volterra series symbol

[Julian18]

Hi, there
In volterra series literatures, the symbol ° can be found everywhere, such as in
V = B(w)°vs + B(w1,w2)°vs^2 + ....

what does this symbol mean?


TIA.

Added after 3 hours 48 minutes:

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[Julian18]

anyone has some ideas about this symbol?

 

[fanshuo]

it is very complicated in form
please referred the book
"VLSI for wireless communication" by B.Leung
there is some introduction

 

[Julian18]

it is very complicated in form
please referred the book
"VLSI for wireless communication" by B.Leung
there is some introduction

Thanks fanshuo
but I cannot get this book, any link to download that or any other reference papers?

 

[fanshuo]

you can find it in the ebook sector of this forum

cheers!

 

[mileoung]

sometimes this symbol is used to represent the low-pass equivalent kernels related to baseband Volterra models

Reference
Principles of Digital Transmission: With Wireless Applications
S Benedetto, E Biglieri