In both shows the son/daughter of the main lead are killed.
The main leads both go above and beyond to catch the criminal

Full of action
Male lead is a detective in both
Team bulldog is lighthearted and more comical compared to bad guys
Both male leads are obsessed over catching a person who potentially committed a big crime for a very long time
Both shows don't have only detectives working to catch criminals

-Both male leads go prison when they were innocent
-Both escape from prison with someone's help .
Although with rugal its an ally, but doubtful victory its enemy.

-Both male lead go to prison although falsely charged, because of threats of harming someone close to them, if they don't admit the crime
-Both escape from prison after years

Both female leads are single mother cops,
both showing the difficulty of keeping promises to their daughters, and the fear of the girls getting into danger.

Both have the theme of revenge for murder, in 'the guardian' its of the daughter, in 'mrs cop' its the father

Whilst 'mrs cop' is more lighthearted, 'the guardians' is more thrilling.

Both mysterious and thrilling.
Both have a way of changing the future, where in 'Signal' is through communicating in to the past through a walky talky, and '365: repeat the year' is by going back exactly one year.
There are also detectives as leads in both shows.

If you like the thriller, the suspense and the cliffhangers like in 'circle', then '365: repeat the year' should be your next destination.