Autonomous transmit chain delay measurements

Abstract

A system and method for determining transmission delay in a communications system. In some embodiments, satellite positioning information having System Frame Number (SFN) information may be received for a mobile device and observed time difference of arrival (OTDOA) measurements may be received for a mobile device. A location of the mobile device may be determined as a function of the received satellite positioning information. A Global Positioning System (GPS) time estimate may be determined as a function of the determined location of the mobile device. Transmission delay between a node serving the mobile device and an antenna serving the mobile device may be determined as a function of the received OTDOA measurements and determined GPS time estimate.

We claim: 
     
       1. A method of determining transmission delay in a communications network having a plurality of nodes comprising the steps of:
 (a) receiving satellite positioning information for a mobile device, the received satellite positioning information including System Frame Number (SFN) information; 
 (b) receiving observed time difference of arrival (OTDOA) measurements for a mobile device from one or more of the plural nodes; 
 (c) determining a location of the mobile device as a function of the received satellite positioning information; 
 (d) determining a Global Positioning System (GPS) time estimate as a function of the determined location of the mobile device; and 
 (e) determining transmission delay between a node serving the mobile device and an antenna serving the mobile device as a function of the received OTDOA measurements and determined GPS time estimate. 
 
     
     
       2. The method of  claim 1  wherein the step of receiving satellite positioning information further comprises requesting the mobile device to report a GPS to network time relationship. 
     
     
       3. The method of  claim 1  wherein the serving node is an eNodeB. 
     
     
       4. The method of  claim 1  wherein the OTDOA measurements include SFN initialization time. 
     
     
       5. The method of  claim 1  further comprising the step of determining propagation delay between the serving antenna and the mobile device as a function of the determined mobile device location and location of the serving antenna, wherein the determined transmission delay is a function of the determined propagation delay. 
     
     
       6. The method of  claim 5  wherein the determined propagation delay is a function of a transmission path from the mobile device to the serving antenna or from the serving antenna to the mobile device. 
     
     
       7. The method of  claim 1  wherein the step of determining transmission delay further comprises determining cable delay and/or radio frequency component delay. 
     
     
       8. The method of  claim 1  further comprising the step of iteratively repeating step (c) and averaging the determined locations over the iteration. 
     
     
       9. The method of  claim 1  further comprising the step of determining a location of one or more other mobile devices using respective received satellite information, wherein the step of determining transmission delay comprises determining transmission delay as a function of the determined locations of the one or more other mobile devices to minimize bias. 
     
     
       10. The method of claim 1 wherein the serving node is a baseband processing unit. 
     
     
       11. The method of claim 10 wherein a radio frequency front end is positioned between the baseband processing unit and the serving antenna. 
     
     
       12. The method of claim 11 wherein the step of determining transmission delay further comprises determining cable delay or radio frequency component delay. 
     
     
       13. The method of claim 11 wherein the step of determining transmission delay further comprises determining cable delay and radio frequency component delay. 
     
     
       14. A communication system, comprising: 
       a plurality of nodes configured to provide wireless service to one or more mobile devices; 
       one or more processors coupled to a memory, wherein the one or more processors are configured to:
 receive satellite positioning information for a mobile device, the received satellite positioning information including System Frame Number (SFN) information; 
 receive observed time difference of arrival (OTDOA) measurements for the mobile device from one or more of the plural nodes; 
 determine a location of the mobile device as a function of the received satellite positioning information; 
 determine a Global Positioning System (GPS) time estimate as a function of the determined location of the mobile device; and 
 determine transmission delay between a node of the plurality of nodes serving the mobile device and an antenna serving the mobile device as a function of the received OTDOA measurements and determined GPS time estimate. 
 
     
     
       15. The communication system of claim 14, wherein the one or more processors are further configured to request the mobile device to report a GPS to network time relationship. 
     
     
       16. The communication system of claim 14, wherein the serving node is an eNodeB. 
     
     
       17. The communication system of claim 14, wherein the OTDOA measurements include SFN initialization time. 
     
     
       18. The communication system of claim 17, wherein the one or more processors are further configured to determine propagation delay between the serving antenna and the mobile device as a function of the determined mobile device location and location of the serving antenna, wherein the determined transmission delay is a function of the determined propagation delay. 
     
     
       19. The communication system of claim 18, wherein the determined propagation delay is a function of a transmission path from the mobile device to the serving antenna or from the serving antenna to the mobile device. 
     
     
       20. The communication system of claim 14, wherein the one or more processors are configured to determine transmission delay between the node serving the mobile device and the antenna serving the mobile device by determining cable delay and/or radio frequency component delay. 
     
     
       21. The communication system of claim 14, wherein the one or more processors are further configured to iteratively repeat determining a location of the mobile device as a function of the received satellite positioning information and average the determined locations over the iteration. 
     
     
       22. The communication system of claim 14, wherein the one or more processors are configured to determine a location of one or more other mobile devices using respective received satellite information;
 wherein the one or more processors are configured to determine transmission delay between the node serving the mobile device and the antenna serving the mobile device by determining transmission delay as a function of the determined locations of the one or more other mobile devices to minimize bias.   
     
     
       23. The communication system of claim 14, wherein the serving node is a baseband processing unit. 
     
     
       24. The communication system of claim 23, wherein a radio frequency front end is positioned between the baseband processing unit and the serving antenna. 
     
     
       25. The communication system of claim 24, wherein the one or more processors are configured to determine transmission delay between the node serving the mobile device and the antenna serving the mobile device by determining cable delay or radio frequency component delay. 
     
     
       26. The communication system of claim 24, wherein the one or more processors are configured to determine transmission delay between the node serving the mobile device and the antenna serving the mobile device by determining cable delay and radio frequency component delay.