Redundancy of distributed antenna systems

A distributed antenna system connected to a first base station and a second base station which provide a duplication-based service and configured to support high availability, the distributed antenna system comprising:

• a first headend unit configured to receive a mobile communication signal from the first base station, generate and transmit a downlink frame, and configure and manage topology information of the distributed antenna system;
• a second headend unit configured to receive a mobile communication signal from the second base station, generate and transmit a downlink frame, and configure and manage topology information of the distributed antenna system;
• and
• a third branch group and a fourth branch group each comprising a plurality of remote units branched from and connected to the first headend unit and the second headend unit, configured to restore a mobile communication signal from a downlink frame received from the first headend unit or the second headend unit and transmit the mobile communication signal through an antenna in a wireless manner, and connected to one another in cascade,
• wherein
• one of the first headend unit or the second headend unit is in an active state, the other headend unit is in a standby state, and each headend unit adds a state bit indicating a duplication state to a control field of the downlink frame and then transmits the downlink frame, and
• the remote unit of the third branch group or the fourth branch group that has received the downlink frame delivers only a frame received from an active headend unit to a sub-node connected to a cascade port.

A duplication method for a distributed antenna system, the duplication method comprising:

• an operation in which a hub unit or a remote unit directly connected to a first headend unit and a second headend unit performs quality measurement on a received downlink;
• an operation in which the hub unit or the remote unit adds a bit error rate (BER) value obtained by the quality measurement to a control field of an uplink frame and transmits the uplink frame to the first headend unit and the second headend unit;
• an operation in which an active headend unit compares the BER value to a predetermined BER threshold value and determines whether to perform switching;
• and
• an operation in which the active headend unit performs the switching according to the switching determination.

A duplication method for a distributed antenna system, the duplication method comprising:

• an operation in which an active headend unit detects an error having occurred in a frame transmission path;
• an operation in which the active headend unit determines a redundancy path to be activated and a hub unit or a remote unit for which a frame transmission path is to be changed on the basis of stored topology information and redundancy link connection information;
• an operation in which the active headend unit blocks a downlink port for the frame transmission path in which the error has occurred;
• and
• an operation in which the active headend unit requests the activation of a redundancy link from a hub unit or a remote unit at one end to which the redundancy link is connected from a branch group in which the error has occurred.

A duplication method for a distributed antenna system, the duplication method comprising:

• an operation in which an active headend unit detects a recovery of an error having occurred in a frame transmission path;
• an operation in which the active headend unit determines a hub unit or a remote unit for which a frame transmission path needs to be changed to switch to a normal frame transmission path on the basis of stored topology information and redundancy link connection information;
• an operation in which the active headend unit requests a path setting change from a hub unit or a remote unit for which the frame transmission path is determined to be changed;
• and
• an operation in which the active headend unit requests the blocking of the redundancy link from a hub unit or a remote unit at one end to which the redundancy link is connected from a branch group in which the error is recovered.