Database cold backup using RMAN is consistent or inconsistent backup ?

 DB ver: 11.1.0.6 (Noachivelog mode)

I am taking database cold backup (including controlfile autobackup) using RMAN. Following are the rman commands I am using for backup and restore:

Backup:
--------
rman>startup mount;
run {
allocate channel t1 device type disk;
backup database;
release channel t1;
}

Retore:
--------
rman> startup nomount;
run {
allocate channel t1 device type disk;
restore controlfile from autobackup;
alter database mount;
restore database;
release channel t1;
}

After the restore when I am trying to open the database, I am getting following error:
 
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open