End-to-end delay management for distributed communications networks

Abstract

A method for calculating delay in a distributed antenna system includes sending a ping initiation message from a remote node to a host node in a distributed antenna system. The ping initiation message uniquely identifies a first communication port of the remote node to the host node with a unique identification. The method also includes receiving a ping reply message at the remote node. The ping reply message corresponds to the ping initiation message and also uniquely identifies the first communication port of the remote node with the unique identification. The method also includes determining, at the remote node, whether the ping reply message corresponds to the first communication port of the remote node based on the unique identification. The method also includes, when the ping reply message corresponds to the first communication port of the remote node, calculating the round-trip time delay between sending the ping initiation message and receiving the ping reply message at the remote node.

The invention claimed is: 
     
         1 . A distributed antenna system comprising:
 a host node including a host node processor, the host node having a first communication port communicatively coupled to a base station of a mobile telephone network, the host node also having a second communication port;   a first remote node in communication with the host node, the first remote node including a first remote node processor, a third communication port communicatively coupled to the second communication port of the host node across a first distinct signal path, and a fourth communication port communicatively coupled to a first antenna;   a second remote node in communication with the host node, the second remote node including a second remote node processor, a fifth communication port communicatively coupled to at least one of a third communication port of the host node and a sixth communication port of the first remote node across a second distinct signal path, and a seventh communication port communicatively coupled to a second antenna;   wherein the first remote node processor comprises program instructions that:
 cause the first remote node to send a first ping initiation message to the host node across the first distinct signal path, wherein the first ping initiation message includes a first unique identification that uniquely identifies at least one of the third communication port and the fourth communication port of the first remote node to the host node; 
 cause the first remote node to determine whether a first ping reply message received from the host node corresponds to the at least one of the third communication port and the fourth communication port of the first remote node based on the first unique identification; and 
 when the first ping reply message received from the host node corresponds to the at least one of the third communication port and the fourth communication port of the first remote node, cause the first remote node to calculate a first elapsed time between sending the first ping initiation message and receiving the first ping reply message; 
   wherein the second remote node processor comprises program instructions that:
 cause the second remote node to send a second ping initiation message to the host node across the second distinct signal path, wherein the second ping initiation message includes a second unique identification that uniquely identifies at least one of the fifth communication port, the sixth communication port, and the seventh communication port of the second remote node to the host node; 
 cause the second remote node to determine whether a second ping reply message received from the host node corresponds to the at least one of the fifth communication port, the sixth communication port, and the seventh communication port of the second remote node based on the second unique identification; and 
 wherein the second ping reply message received from the host node corresponds to the at least one of the fifth communication port, the sixth communication port, and the seventh communication port of the second remote node, cause the second remote node to calculated a second elapsed time between sending the second ping initiation message and receiving the second ping reply message; and 
   wherein the host node processor comprises program instructions that:
 cause the host node to validate the first ping initiation message received from the first remote node; 
 when the first ping initiation message is validated, cause the host node to send the first ping reply message to the first remote node, wherein the first ping reply message corresponds to the first ping initiation message and also uniquely identifies the at least one of the third communication port and the fourth communication port of the first remote node; 
 cause the host node to validate the second ping initiation message received from the second remote node; and 
 wherein the second ping initiation message is validated, cause the host node to send the second ping reply message to the second remote node, wherein the second ping reply message corresponds to the second ping initiation message and also uniquely identifies the at least one of the fifth communication port, the sixth communication port, and the seventh communication port. 
   
     
     
         2 . The distributed antenna system of  claim 1 , wherein the first unique identification is a path code that identifies a first path between the at least one of the third communication port and the fourth communication port of the first remote node and at least one of the first communication port and the second communication port of the host node. 
     
     
         3 . The distributed antenna system of  claim 2 , wherein the path code uniquely identifies the host node, the at least one of the first communication port and the second communication port, the at least one of the third communication port and the fourth communication port, and the first distinct signal path between the host node and the first remote node. 
     
     
         4 . The distributed antenna system of  claim 1 , wherein the first remote node is separated from the host node by at least one additional remote node. 
     
     
         5 . The distributed antenna system of  claim 1 , wherein at least one of the first communication port and the fourth communication port is part of a radio frequency to digital interface that converts between radio frequency signals and digital signals. 
     
     
         6 . The distributed antenna system of  claim 1 , wherein a single bit in each timeslot of a data frame is used to transmit the first ping initiation message and the first ping reply message. 
     
     
         7 . The distributed antenna system of  claim 1 , wherein the first remote node processor program instructions further cause the first remote node to:
 verify whether the fourth communication port of the first remote node is compatible with a first type of the first communication port of the host node based on the first ping reply message received from the host node.   
     
     
         8 . The distributed antenna system of  claim 7 , wherein the first remote node processor program instructions further cause the first remote node to at least one of:
 mute the fourth communication port of the first remote node when it is determined that the fourth communication port of the first remote node is not compatible with the first type of the first communication port of the host node; and   trigger an alarm to indicate a mismatch between the first type of the first communication port of the host node and the fourth communication port of the first remote node.   
     
     
         9 . The distributed antenna system of  claim 1 , wherein the host node processor program instructions cause the host to validate the first ping initiation message received from the first remote node by validating at least one of a message type, a host base station interface type, a host node ID number, a host base station ID number, and a cyclic redundancy check code. 
     
     
         10 . The distributed antenna system of  claim 1 , wherein the host node processor program instructions further cause the host node to:
 trigger an alarm if certain items in the first ping initiation message received from the first remote node are not validated by the host node.   
     
     
         11 . The distributed antenna system of  claim 1 , wherein at least one of the host node processor and the first remote node processor is at least one of a programmable processor, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a field-programmable object array (FPOA), and a programmable logic device (PLD). 
     
     
         12 . A method for calculating delay in a distributed antenna system comprising:
 sending a first ping initiation message from a first remote node in the distributed antenna system to a host node in the distributed antenna system across a first distinct signal path coupling the first remote node to the host node, wherein the first ping initiation message uniquely identifies a first communication port of the first remote node to the host node with a first unique identification;   receiving a first ping reply message at the remote node from the host node, the first ping reply message transmitted from the host node to the first remote node across the first distinct signal path coupling the first remote node to the host node;   determining, at the first remote node, whether the first ping reply message uniquely identifies the first communication port of the first remote node with the first unique identification;   when the first ping reply message uniquely identifies the first communication port of the first remote node, calculating a first round-trip time delay between sending the first ping initiation message and receiving the first ping reply message at the first remote node;   sending a second ping initiation message from a second remote node in the distributed antenna system to the host node in the distributed antenna system across a second distinct signal path coupling the second remote node to the host node, wherein the second ping initiation message uniquely identifies a second communication port of the second remote node to the host node with a second unique identification;   receiving a second ping reply message at the remote node from the host node, the second ping reply message transmitted from the host node to the second remote node across the second distinct signal path coupling the second remote node to the host node;   determining, at the second remote node, whether the second ping reply message uniquely identifies the second communication port of the second remote node with the second unique identification; and   when the second ping reply message uniquely identifies the second communication port of the second remote node, calculating a second round-trip delay between sending the second ping initiation message and receiving the second ping reply message at the second node.   
     
     
         13 . The method of  claim 12 , wherein the first unique identification is a path code that identifies a first path between the first communication port of the remote node and a third communication port of the host node. 
     
     
         14 . The method of  claim 13 , wherein the path code uniquely identifies the host node, the first communication port, the third communication port, and the first distinct signal path between the host node and the first remote node. 
     
     
         15 . The method of  claim 12 , further comprising:
 calculating a first signal path delay at the first remote node based on the first round-trip delay.   
     
     
         16 . The method of  claim 15 , wherein calculating the first signal path delay includes:
 dividing the first round-trip delay by a number to determine a one-way delay between at least one of sending and receiving the first ping initiation message and sending and receiving the first ping reply message.   
     
     
         17 . The method of  claim 15 , wherein calculating the first signal path delay includes:
 factoring intrinsic processing delays into the calculation of the first signal path delay.   
     
     
         18 . The method of  claim 17 , wherein the intrinsic processing delays are pre-determined processing delays associated with internal processing occurring at least one of the host node and the first remote node. 
     
     
         19 . The method of  claim 15 , wherein the first signal path delay approximates at least one of:
 a forward path time delay between radio frequency spectrum being received at a radio frequency port of the host node and being output at a radio frequency port of the first remote node; and   a reverse path time delay between radio frequency spectrum being received at the radio frequency port of the first remote node and being output at the radio frequency port of the host node.   
     
     
         20 . The method of  claim 12 , further comprising forwarding the first ping initiation message received from the first remote node toward the host node at a third remote node positioned between the first remote node and the host node; and
 forwarding the first ping reply message received from the host node toward the first remote node at the third remote node positioned between the first remote node and the host node.   
     
     
         21 . The method of  claim 12 , wherein validating the first ping initiation message includes at least one of performing a cyclic redundancy check on the first ping initiation message, validating a message type, validating a host base station interface type, validating a host node ID number, and validating a host base station ID number. 
     
     
         22 . The method of  claim 12 , further comprising:
 determining, at the first remote node, whether the first ping reply message is received before a predefined timeout period elapses since the first ping initiation message was sent before determining whether the first ping reply message uniquely identifies the first communication port of the first remote node with the first unique identification; and   wherein determining whether the first ping reply message uniquely identifies the first communication port of the first remote node with the first unique identification only occurs when the first ping reply message is received before the predefined timeout period elapses since the first ping initiation message was sent;   when the first ping reply message is not received before the predefined timeout period elapses, determining whether a predefined number of unsuccessful attempts at sending the first ping initiation message has been reached;   when the predefined number of unsuccessful attempts at sending the first ping initiation message has been reached, resending the first ping initiation message when a next ping trigger occurs.   
     
     
         23 . The method of  claim 22 , wherein the next ping trigger occurs at a pseudo-random time determined using a pseudo-random back-off algorithm to minimize the chance of a collision between other upstream messages. 
     
     
         24 . The method of  claim 12 , further comprising:
 determining, at the first remote node, whether the first ping reply message has been successfully received a predefined number of times; and   wherein calculating the first round-trip time delay between sending the first ping initiation message and receiving the first ping reply message at the first remote unit only occurs when the first ping reply message has been successfully received a predefined number of times; and   when the first ping reply message has not been successfully received a predefined number of times, resending the first ping initiation message when a next ping trigger occurs.   
     
     
         25 . The method of  claim 24 , wherein the next ping trigger occurs at a pseudo-random time determined using a pseudo-random back-off algorithm to minimize the chance of a collision between other upstream messages. 
     
     
         26 . The method of  claim 12 , further comprising:
 when the first ping reply message received at the first remote node does not correspond to at least one communication port of the first remote node, ignoring the first ping reply message at the first remote node.   
     
     
         27 . The method of  claim 12 , further comprising:
 determining, at the first remote node, whether a predefined number of unsuccessful attempts at sending the first ping initiation message has been reached; and   when the predefined number of unsuccessful attempts at sending the first ping initiation message has been reached, reporting a path integrity alarm.   
     
     
         28 . The method of  claim 12 , further comprising:
 converting messages received from an antenna connected to the first remote node from first radio frequency signals to first digital signal; and   converting messages to be transmitted via the antenna from second digital signals to second radio frequency signals.   
     
     
         29 . The method of  claim 12 , further comprising:
 receiving the first ping initiation message at the host node;   validating the first ping initiation message at the host node; and   when the first ping initiation message is validated, sending the first ping reply message to the first remote node.   
     
     
         30 . The method of  claim 29 , further comprising:
 when a third message received at the host node is not validated at the host node, ignoring the third message.   
     
     
         31 . The method of  claim 29 , further comprising:
 converting messages received from an antenna connected to the host node from first radio frequency signals to first digital signals; and   converting messages to be transmitted via the antenna from second digital signals to second radio frequency signals.   
     
     
         32 . The method of  claim 12 , wherein a single bit in each timeslot of a data frame is used to transmit the first ping initiation message and the first ping reply message. 
     
     
         33 . The method of  claim 12 , further comprising:
 after calculating the first round-trip time delay between sending the first ping initiation message and receiving the first ping reply message at the first remote node, resetting an attempts count and a message received count, wherein the attempts count tracks how many unsuccessful attempts have been made at pinging the host node, wherein the message received count tracks how many times the message has been successfully received.   
     
     
         34 . The method of  claim 12 , further comprising:
 waiting for a next ping trigger;   once the next ping trigger has occurred, sending a third ping initiation message from the first remote node to the host node, wherein the third ping initiation message uniquely identifies a third communication port of the first remote node to the host node with a third unique identification;   receiving a third ping reply message at the first remote node;   determining, at the first remote node, whether the third ping reply message uniquely identifies the third communication port of the first remote node with the third unique identification; and   when the third ping reply message uniquely identifies the third communication port of the first remote node, calculating a third round-trip time delay between sending the third ping initiation message and receiving the third ping reply message at the first remote node.   
     
     
         35 . A plurality of remote nodes in a distributed antenna system comprising:
 a first remote node having:
 a first communication port communicatively coupled to a first antenna; 
 a second communication port communicatively coupled to a host node; and 
 a first remote node processor, wherein the first remote node processor comprises program instructions that:
 cause the first remote node to send a first ping initiation message to the host node across a first communication link established across a first distinct signal path between the second communication port and the host node, wherein the first ping initiation message includes a first unique identification that uniquely identifies at least one of the first communication port and the second communication port of the first remote node to the host node; 
 cause the first remote node to determine whether a first ping reply message received from the host node corresponds to the at least one of the first communication port and the second communication port of the first remote node based on the first unique identification; and 
 when the first ping reply message received from the host node corresponds to the at least one of the first communication port and the second communication port, cause the first remote node to calculate the elapsed time between sending the first ping initiation message and receiving the first ping reply message 
 
   a second remote node having:
 a third communication port communicatively coupled to a second antenna; 
 a fourth communication port communicatively coupled to the host node; and 
 a second remote node processor, wherein the second remote node processor comprises program instructions that:
 cause the second remote node to send a second ping initiation message to the host node across a second communication link established across a second distinct signal path between the fourth communication port and the host node, wherein the second ping initiation message includes a second unique identification that uniquely identifies at least one of the third communication port and the fourth communication port of the second remote node to the host node; 
 cause the second remote node to determine whether a second ping reply message received from the host node corresponds to the at least one of the third communication port and the fourth communication port of the second remote node based on the second unique identification; and 
 when the second ping reply message received from the host node corresponds to the at least one of the third communication port and the fourth communication port, cause the second remote node to calculate the elapsed time between sending the second ping initiation message and receiving the second ping reply message. 
 
   
     
     
         36 . The plurality of remote nodes of  claim 35 , wherein the first unique identification is a path code that identifies a path between the at least one of the first communication port and the second communication port of the first remote node and at least one communication port of the host node. 
     
     
         37 . The plurality of remote nodes of  claim 36 , wherein the path code uniquely identifies the host node, the at least one communication port of the host node, the at least one of the first communication port and the second communication port of the remote node, and the first distinct signal path between the host node and the first remote node. 
     
     
         38 . The plurality of remote nodes of  claim 35 , wherein the first remote node is separated from the host node by at least one additional remote node in the distributed antenna system. 
     
     
         39 . The plurality of remote nodes of  claim 35 , wherein the first communication port is part of a radio frequency to digital interface that converts between radio frequency signals and digital signals. 
     
     
         40 . The plurality of remote nodes of  claim 35 , wherein a single bit in each timeslot of a data frame is used to transmit the first ping initiation message and the first ping reply message. 
     
     
         41 . The plurality of remote nodes of  claim 35 , wherein the first remote node processor program instructions further cause the first remote node to:
 verify whether the first communication port of the first remote node is compatible with a first type of at least one communication port of the host node based on the first ping reply message received from the host node.   
     
     
         42 . The plurality of remote nodes of  claim 41 , wherein the first remote node processor program instructions further cause the first remote node to at least one of:
 mute the first communication port of the first remote node when it is determined that the first communication port of the first remote node is not compatible with the first type of the at least one communication port of the host node; and   trigger an alarm to indicate a mismatch between the first type of the at least one communication port of the host node and the first communication port of the first remote node.   
     
     
         43 . The plurality of remote nodes of  claim 35 , wherein at least one of the first remote node processor and the second remote node processor is at least one of a programmable processor, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a field-programmable object array (FPOA), and a programmable logic device (PLD). 
     
     
         44 . A program product comprising program instructions, embodied on a non-transitory storage medium, the program instructions cause at least one programmable processor in each of a plurality of remote nodes within a distributed antenna system to:
 cause a particular remote node to send a ping initiation message to a host node across a communication link established across a distinct signal path between the remote node and the host node, wherein the ping initiation message includes a unique identification that uniquely identifies at least one communication port of the remote node to the host node;   cause the particular remote node to determine whether a ping reply message received from the host node corresponds to the at least one communication port of the remote node based on the unique identification; and   when the ping reply message received from the host node corresponds to the at least one communication port of the remote node based on the unique identification, calculate the elapsed time between sending the ping initiation message and receiving the ping reply message.   
     
     
       45. A distributed antenna system comprising:
 a host node circuitry comprising a first programmable processor, a first signal interface communicatively coupled to a base station via a first signal interface connection, and a first transport interface;   a first remote node circuitry in communication with the host node circuitry, the first remote node circuitry comprising a second programmable processor, a second transport interface communicatively coupled to the first transport interface of the host node circuitry across a first distinct transport connection having a first end at the first transport interface of the host node circuitry and a second end at the second transport interface of the first remote node circuitry, and a second signal interface communicatively coupled to a first antenna;   a second remote node circuitry in communication with the host node circuitry, the second remote node circuitry comprising a third programmable processor, a third transport interface communicatively coupled to the first transport interface of the host node circuitry across a second distinct transport connection having a third end at the first transport interface of the host node circuitry and a fourth end at the third transport interface of the second remote node circuitry, and a third signal interface communicatively coupled to a second antenna;   wherein the first remote node circuitry is configured to:
 send a first initiation message to the host node circuitry across the first distinct transport connection as part of a process to determine signal delay, wherein the first initiation message includes a first unique identification that uniquely identifies the second end of the first distinct transport connection at the first remote node circuitry; 
 determine whether a first reply message, received from the host node circuitry as part of the process to determine signal delay, corresponds to the second end of the first distinct transport connection based on the first unique identification; and 
 when the first reply message received from the host node circuitry corresponds to the second end of the first distinct transport connection, calculate a first elapsed time between sending the first initiation message and receiving the first reply message; 
   wherein the second remote node circuitry is configured to:
 send a second initiation message to the host node circuitry across the second distinct transport connection as part of the process to determine signal delay, wherein the second initiation message includes a second unique identification that uniquely identifies the fourth end of the second distinct transport connection at the second remote node circuitry; 
 determine whether a second reply message, received from the host node circuitry as part of the process to determine signal delay, corresponds to the fourth end of the second distinct transport connection based on the second unique identification; 
 when the second reply message received from the host node circuitry includes the second unique identification, calculate a second elapsed time between sending the second initiation message and receiving the second reply message, wherein calculation of the first elapsed time and the second elapsed time enables synchronization of delays between the host node circuitry and the first remote node circuitry and the second remote node circuitry; and 
   wherein the host node circuitry is configured to:
 send the first reply message to the first remote node circuitry, wherein the first reply message corresponds to the first initiation message and also uniquely identifies the second end of the first distinct transport connection at the first remote node circuitry; and 
 send the second reply message to the second remote node circuitry, wherein the second reply message corresponds to the second initiation message and also uniquely identifies the fourth end of the second distinct transport connection at the second remote node circuitry.  
   
     
     
       46. The distributed antenna system of  claim 45 , wherein the first unique identification is a path code that identifies a first path between the second end of the first distinct transport connection at the second transport interface of the first remote node circuitry and the first end of the first distinct transport connection at the first transport interface of the host node circuitry.  
     
     
       47. The distributed antenna system of  claim 46 , wherein the path code uniquely identifies the first remote node circuitry, the second transport interface of the first remote node circuitry, the first distinct transport connection, the first transport interface of the host node circuitry, and the host node circuitry.  
     
     
       48. The distributed antenna system of  claim 45 , wherein the first remote node circuitry is separated from the host node circuitry by at least one additional remote node circuitry in the distributed antenna system.  
     
     
       49. The distributed antenna system of  claim 45 , wherein a single bit in each timeslot of a data frame is used to transmit the first initiation message and the first reply message.  
     
     
       50. The distributed antenna system of  claim 45 , wherein the first remote node circuitry is further configured to:
 verify whether the second transport interface of the first remote node circuitry is compatible with a first type of the first transport interface of the host node circuitry based on based on the first reply message received from the host node circuitry.    
     
     
       51. The distributed antenna system of  claim 50 , wherein the first remote node circuitry is further configured to at least one of:
 mute the second transport interface of the first remote node circuitry when it is determined that the second transport interface of the first remote node circuitry is not compatible with the first type of the first transport interface of the host node circuitry; and   trigger an alarm to indicate a mismatch between the first type of the first transport interface of the host node circuitry and the second transport interface of the first remote node circuitry.    
     
     
       52. The distributed antenna system of  claim 45 , wherein at least one of the first programmable processor, the second programmable processor, and the third programmable processor include at least one of a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a field-programmable object array (FPOA), and a programmable logic device (PLD).  
     
     
       53. A remote node circuitry for use within a distributed antenna system having a plurality of remote node circuitries, the remote node circuitry comprising:
 a first signal interface communicatively coupled to an antenna;   a first transport interface communicatively coupled to a second transport interface of a host node circuitry across a distinct transport connection having a first end at the first transport interface of the remote node circuitry and a second end at the second transport interface of the host node circuitry; and   a programmable processor, wherein the programmable processor causes the remote node circuitry to:
 send an initiation message to the host node circuitry using the first transport interface and across the distinct transport connection as part of a process to determine signal delay, wherein the initiation message includes a unique identification that uniquely identifies the first end of the distinct transport connection at the remote node circuitry; 
 receive a reply message from the host node circuitry across the distinct transport connection and via the first transport interface as part of the process to determine signal delay, wherein the reply message includes the unique identification that uniquely identifies the first end of the distinct transport connection at the remote node circuitry; 
 determine whether the reply message corresponds to the first end of the distinct transport connection at the remote node circuitry based on the unique identification; 
 calculate elapsed time between sending the initiation message and receiving the reply message when the reply message corresponds to the first end of the distinct transport connection at the remote node circuitry; and 
 wherein calculation of the elapsed time enables synchronization of delays between the host node circuitry and the remote node circuitry and other remote node circuitries of the plurality of remote node circuitries.  
   
     
     
       54. The remote node circuitry of  claim 53 , wherein the unique identification is a path code that identifies a path between the first end of the distinct transport connection at the first transport interface of the remote node circuitry and the second end of the distinct transport connection at the second transport interface of the host node circuitry.  
     
     
       55. The remote node circuitry of  claim 54 , wherein the path code uniquely identifies the remote node circuitry, the first transport interface of the remote node circuitry, the distinct transport connection, the second transport interface of the host node circuitry, and the host node circuitry.  
     
     
       56. The remote node circuitry of  claim 53 , wherein the remote node circuitry is separated from the host node circuitry by at least one additional remote node circuitry of the plurality of remote node circuitries in the distributed antenna system.  
     
     
       57. The remote node circuitry of  claim 53 , wherein a single bit in each timeslot of a data frame is used to transmit the initiation message and the reply message.  
     
     
       58. The remote node circuitry of  claim 53 , wherein the programmable processor further causes the remote node circuitry to:
 verify whether the first transport interface of the remote node circuitry is compatible with a first type of the second transport interface of the host node circuitry based on the reply message received from the host node circuitry.    
     
     
       59. The remote node circuitry of  claim 58 , wherein the programmable processor further causes the remote node circuitry to at least one of:
 mute the first transport interface of the remote node circuitry when it is determined that the first transport interface of the remote node circuitry is not compatible with the first type of the second transport interface of the host node circuitry; and   trigger an alarm to indicate a mismatch between the first type of second transport interface of the host node circuitry and the first transport interface of the remote node circuitry.    
     
     
       60. The remote node circuitry of  claim 53 , wherein the programmable processor is at least one of a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a field-programmable object array (FPOA), and a programmable logic device (PLD).  
     
     
       61. A program product comprising computer-readable program instructions, embodied on a non-transitory storage medium, that when executed by at least one programmable processor in a remote node circuitry of a plurality of remote node circuitries within a distributed antenna system, cause the remote node circuitry to:
 send an initiation message to a host node circuitry across a distinct transport connection established between a first transport interface of the remote node circuitry and a second transport interface of the host node circuitry of the distributed antenna system as part of a process to determine signal delay, wherein the distinct transport connection includes a first end at the first transport interface of the remote node circuitry and a second end at the second transport interface of the host node circuitry, wherein the initiation message includes a unique identification that uniquely identifies the first end of the distinct transport connection at the remote node circuitry, wherein the distinct transport connection is used for data communication;   receive a reply message from the host node circuitry across the distinct transport connection and via the first transport interface as part of the process to determine the signal delay, wherein the reply message includes the unique identification that uniquely identifies the first end of the distinct transport connection at the remote node circuitry;   determine whether the reply message corresponds to the first end of the distinct transport connection at the remote node circuitry based on the unique identification;   calculate elapsed time between sending the initiation message and receiving the reply message when the reply message corresponds to the first end of the distinct transport connection at the remote node circuitry; and   wherein calculation of the elapsed time enables synchronization of delays between the host node circuitry and the remote node circuitry and other remote node circuitries of the plurality of remote node circuitries.    
     
     
       62. The program product of  claim 61 , wherein the unique identification is a path code that identifies a path between the first end of the distinct transport connection at the first transport interface of the remote node circuitry and the second end of the distinct transport connection at the second transport interface of the host node circuitry.  
     
     
       63. The program product of  claim 61 , wherein the remote node circuitry is separated from the host node circuitry by at least one additional remote node circuitry of the plurality of remote node circuitries in the distributed antenna system.  
     
     
       64. The program product of  claim 61 , wherein a single bit in each timeslot of a data frame is used to transmit the initiation message and the reply message.