I must have unlocked bootloader to update at & t 4.0.4 to 4.1.1 official with rds lit

to install official 4.1.1 rom android at & t with rsd lite booloader I must have unlocked? I have no root andrpid 4.0.4.

if necessary unlocked bootloader which guide I must follow to be root and have booloader unlocked android 4.0.4

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