use strict;
use warnings;

my $text = "Signal\nLTE-FDD 4; Channel 2175";
my $band = "";
my $channel = "";
my $temp = "";
if($text =~ /Signal\nLTE-FDD [\d]{1,2}; Channel [\d]{3,4}/i)
{
      $temp = $&;       #store regex match
      $temp =~ /LTE-FDD [\d]{1,2};/i;   
      $& =~ /[\d]{1,2}/i;
      $band = $&;       #store regex match
      $temp =~ /Channel [\d]{3,4}/i;
      $& =~/[\d]{3,4}/i;
      $channel = $&;    #store rege match
}
print "$band\t$channel\n";