Transport cable redundancy in a distributed antenna system using digital transport

Abstract

A redundancy system for a distributed antenna system is provided. The system includes a first communication link, a second communication link, a first communication node and a second communication node. The first communication link traverses first path. The second communication link traverses a second path. The second path is spatially separated from the first path. The first communication node is communicatively coupled to transmit the same signal through both the first communication link and the second communication link. The second communication node has a receiver system that is communicatively coupled to receive the signals transmitted through the first and second communication links. The receiver system is configured to synchronize delay and phase differences between the received signals and then combine the signals together to generate a single output.

1 . A redundancy system for a distributed antenna system, the system comprising:
 a first communication node;   at least one second communication node;   a communication link communicatively coupling the first communication node to the at least one second communication node in a ring topography, the communication link having a first portion that is spatially separated from a second portion;   at least one sensor configured to measure signal power level of communication signals in at least one of the first portion and the second portion of the communication link;   at least one switch positioned within at least one of the first portion and the second portion of the communication link to selectively communicatively couple communication signals between the first communication node and the at least one second communication node through one of the first portion and the second portion of the communication link; and   a controller in communication with the at least one sensor, the controller configured to activate the at least one switch upon the at least one sensor measuring a signal power level in one of the first portion and the second portion of the communication link below a threshold.   
     
     
         2 . The system of  claim 1 , wherein:
 the first communication node is a master unit; and   the at least one second communication node is at least one remote antenna unit.   
     
     
         3 . The system of  claim 1 , the first communication node comprising:
 a first wavelength division multiplier having an output communicatively coupled to the first portion of the communication link;   a second wavelength division multiplier having an output communicatively coupled to the second portion of the communication link;   at least one transmitter;   a splitter for each transmitter, each splitter having an input communicatively coupled to an output of an associated transmitter, each splitter having a first output commutatively coupled to an input of the first wavelength division multiplexer and a second output communicatively coupled to an input of the second wavelength division multiplexer;   at least one receiver; and   a combiner for each receiver, each combiner having an output communicatively coupled to an input of an associated receiver, each combiner having a first input coupled to an output of the first wavelength division multiplexer and a second input communicatively coupled to an output of the second wavelength division multiplexer.   
     
     
         4 . The system of  claim 1 , wherein the at least one second communication node includes at least two second communication nodes, the system further comprising:
 an add/drop multiplexer for each second communication node, each add/drop multiplexer communicatively coupled to the communication link, each add/drop multiplexer configured to pass communication signals in the communication link to an associated second communication node.   
     
     
         5 . A method of operating a redundancy system for a distributed antenna system having communication nodes selectively coupled in a ring topography via at least one switch, the method comprising:
 monitoring power levels of communication signals in a first portion of a communication link that communicatively couples the communication nodes in the ring topography; and   when a power level is detected below a threshold, activating the at least one switch to allow communications between the communication nodes through a second portion of the communication link that is spatially separated from the first portion of the communication link.   
     
     
         6 . The method of  claim 5 , wherein the communication components include at least one master unit and a plurality of remote antenna units, the method further comprising:
 combining downlink messages from the master unit to the first portion of the communication link with a first wave division multiplexer;   separating uplink messages to the maser unit from the first portion of the communication link with the first wave division multiplexer;   combining downlink messages from the master unit to the second portion of the communication link with a second wave division multiplexer; and   separating uplink messages to the maser unit from the second portion of the communication link with the second wave division multiplexer.   
     
     
         7 . The method of  claim 6 , further comprising:
 passing select signals to and from the communication link to a select remote antenna unit with an add/drop multiplexer.   
     
     
         8 . The method of  claim 6 , further comprising:
 splitting a signal from each transmitter in the master unit that is designed to communicate signals to an associated remote antenna unit to an input of each of the first and second wave division multiplexer;   combining an associated output of each of the first and second wave division multiplexer; and   coupling the combined outputs of each of the first and second wave division multiplexer to an associated receiver.