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.

Description

CROSS REFERENCES

where SFN_i represents the SFN initialization time at the n^th eNodeB and may be reported under assistance information from the i^th eNodeB under the OTDOA cell info Information Element (IE), and δ_i represents the delay at the i^th base station between the respective time stamping module and the transmission cell site antenna.

Exemplary embodiments may determine the delay in the transmission path by using A-GNSS or A-GPS capable UEs, SETs or other mobile devices. Of course, A-GNSS and A-GPS are provided as non-limiting examples, as embodiments of the present subject matter may include other exemplary satellite systems such as, but not limited to, GLONASS, Galileo, Compass, BeiDou and the like.

For example, in one embodiment an E-SMLC or equivalent may initiate network assisted GNSS positioning procedures and/or an E-CID procedure to obtain measurements from the UE associated with the procedure. A delay in the transmission path may be determined based upon Timing Advance (TA) measurements from the E-CID procedure and/or a target location determined from any A-GNSS measurements. Thus, to determine the transmission path delay, the UE(s) position(s) determined by or at the E-SMLC may be paired or associated with respective TA measurements for the UE(s) obtained from the E-CID procedure.

In this embodiment of the present subject matter, both A-GPS/GNSS and E-CID positioning may be invoked from the E-SMLC or SLP. In one embodiment, E-CID positioning may be invoked through the control plane to provide better accuracy, and/or A-GPS/GNSS positioning may be invoked through the SLP to minimize messaging overhead in the control plane. Of course, embodiments of the present subject matter should not be so limited as both the control and user planes may be utilized in embodiments of the present subject matter.

If the position of the UE is determined using an exemplary A-GPS/GNSS positioning method, then the TA received using E-CID may be employed to estimate the delay occurring in the transmission path or of the eNodeB as illustrated in FIG. 3. Further information regarding TA is provided in 3GPP TS 36.214, the entirety of which is incorporated herein by reference. With reference to FIG. 3, using an exemplary uplink E-CID positioning method where measurements may be obtained by the eNodeB 310, an E-SMLC may receive measurement results from the serving eNodeB 310 containing TA for a target UE 320 as illustrated in Figure Ia. As described in 3GPP TS 36.455, the entirety of which is incorporated herein by reference, two types of TA information may be available from eNodeBs. According to 3GPP TS 36.214, TA may be determined at the transmission/receiver (Tx/Rx) antenna connector point of the eNodeB. The TA may account for both the propagation path delay and Rx/Tx path delay. Hence, if one assumes that the delay in the Tx and/or Rx path (i.e., the “transmission” path), 8, between the cell site antenna 330 and eNodeB 310 are both equal, then the following relationship may be obtained:
T_{ADV_type1}=2*(τ+δ)  (2)
where, τ represents the propagation delay. Equation (2) may then be rearranged to provide the transmission delay as:
δ=(T_{ADV_type1})/2−τ  (3)

It should be noted that the asymmetry of delay in the Tx and Rx path due to different size of filters in the RF front end may impact the actual delay but should not impact the relative timing of downlink signals as these asymmetries between the Tx and Rx path or chain may not vary significantly from one base station to the other. Further, in embodiments where an SLP invokes an E-CID positioning procedure, T_{ADV_type1} may be replaced by the TA received from a SET within an LTE LID.

The propagation delay τ between the cell site antenna 330 and UE 320 may be determined using knowledge of the position of the UE 320 and the location of the cell site; hence, an A-GPS/A-GNSS capable UE 320 may be used to determine the location of the UE 320. In the absence of TA Type 1, TA Type 2 may also be used. In this embodiment, the transmission delay may be determined using the following relationship:
δ=½(T_{ADV_type2})−τ  (4)

When an E-SMLC, SLP, or other management server or entity desires to characterize the delay in the transmission path or chain for a particular site, a number of GPS/GNSS capable UEs served by that cell may be selected. Thus, the E-SMLC or SLP may invoke A-GNSS and E-CID positioning procedures on the UEs and may retrieve positioning measurements from UE as outlined in 3GPP TS 36.305, 3GPP TS 36.455, and 3GPP TS 36.355, the entirety of each being incorporated herein by reference.

In another embodiment, a delay in the transmission path may be determined from measurements obtained from the A-GNSS positioning procedures and the SFN. Thus, the E-SMLC or equivalent may request the UE to report a GNSS-network-time association when returning A-GNSS signal measurement information. In this embodiment of the present subject matter, an A-GPS/A-GNSS positioning method may be invoked by the E-SMLC or SLP, and the E-SMLC or SLP may receive OTDOA cell information from the serving cell of the UE.

When initiating the A-GNSS method, an exemplary E-SMLC may request the target UE to report GNSS-network time association. The fineTimeAssistanceMeasReq field may be set as TRUE under the IE GNSS-PositioningInstructions as discussed in 3GPP TS 36.355, the entirety of which is incorporated herein by reference. It should be noted that, while not required, the UE may support fine time assistance measurements, as indicated by the field fta-MeasSupport, in the IE A-GNSS-Provide-Capabilities.

When the E-SMLC indicates fineTimeAssistanceMeasReq, then the UE may align the measurement point with a cellular frame boundary and include the same in the network time (e.g., SFN) so that the GNSS time reported may be the time occurs at the frame boundary. FIG. 4 provides an illustration of such an embodiment. With reference to FIG. 4, precise time may be available after position determination, so the E-SMLC may establish the final GNSS-network time relationship. From the positioning determination of the UE, precise GNSS/GPS time of the SFN boundary observed at the UE may be determined. Assuming that the determined GNSS/GPS time of SFN_n observed at the UE is UERx^Nth _SFN, one may determine the propagation delay τ from the cell site antenna to the UE as a function of the determined location of the UE and the cell site location. If transmission time of the downlink frame N from the i^th base station cell site antenna is represented as Tx_eNB_i^{Nth SFN}, where i represents the serving base station, the following relationship may be obtained:
Tx_eNB_i^{Nth SFN}=UERx^{Nth SFN}−τ  (5)

The E-SMLC may also obtain OTDOA cell information of the serving eNodeB including SFN initialization time. The SFN initialization time (in sec relative to 00:00:00 on 1 Jan. 1900) may be translated to GNSS/GPS reference time. Thus, assuming that the translated SFN time is represented as eNB_i^SFN_init, if both eNB_i^SFN_init and Tx_eNB_i^{Nth SFN} are expressed in GPS/GNSS time of day (TOD), then the transmission delay may be determined as provided in the relationship below:
δ=Tx_eNB_i^{Nth SFN}−eNB_i^NFNinit  (6)

To minimize measurement errors, the location of the UE may be obtained from A-GPS/A-GNSS methods by keeping the UE stationary and/or averaging the same over a predetermined number of iterations to minimize UE location error. Tx delay, δ, may thus be obtained by averaging over several times for a stationary UE location. This embodiment may also be repeated by placing UE(s) distributed over the cell area to minimize any bias from a particular location.

Thus, embodiments of the present subject matter may provide a method of determining delay using a mobile device's location and a respective signal's propagation delay. Such delay may include cable and/or other RF component delays. Further, the propagation delay may be either uplink and/or downlink paths and may be averaged for better accuracy.

FIG. 5 is a diagram of one embodiment of the present subject matter. With reference to FIG. 5, a method 500 of determining transmission delay in a communications system is provided. At step 510, the method may include receiving satellite positioning information for a mobile device. At step 520, E-CID positioning information may be received for the mobile device. In some embodiments, the received E-CID positioning information may include timing advance information of an uplink signal transmitted from the mobile device or timing advance information of a downlink signal received by the mobile device. In other embodiments, the E-CID positioning measurements may include timing advance type 1 or timing advance type 2. In yet another embodiment, step 520 may include invoking an E-CID positioning procedure from the UP or from the CoP.

A location of the mobile device may then be determined at step 530 as a function of the received satellite positioning information. At step 540, 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 E-CID positioning information and the determined location of the mobile device. In an alternative embodiment, step 540 may include determining cable delay and/or radio frequency component delay. In one embodiment, the serving node is an eNodeB. In a further embodiment, the method may include 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, where the determined transmission delay is a function of the determined propagation delay. In such a method, the determined propagation delay may be a function of a transmission path from the mobile device to the serving antenna or from the serving antenna to the mobile device. In additional embodiments, the method may include the step of iteratively repeating step 530 and averaging the determined locations over the several iterations. In an alternative embodiment, the method may include the step of determining a location of one or more other mobile devices using respective received satellite information, whereby step 540 would include determining transmission delay as a function of the determined locations of the one or more other mobile devices to minimize bias from any single location determination.

FIG. 6 is a diagram of another embodiment of the present subject matter. With reference to FIG. 6, a method 600 of determining transmission delay in a communications network having a plurality of nodes is provided. The method may include receiving satellite positioning information for a mobile device, the received satellite positioning information including SFN information at step 610 and receiving OTDOA measurements for a mobile device from one or more of the plural nodes at step 620. In one embodiment, step 610 includes requesting the mobile device to report a GPS to network time relationship. In another embodiment, the OTDOA measurements may include SFN initialization time.

A location of the mobile device may be determined as a function of the received satellite positioning information at step 630. At step 640, a GPS time estimate may be determined as a function of the determined location of the mobile device. At step 650, 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. In one embodiment, the serving node is an eNodeB. In a further embodiment, the method may include 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, where the determined transmission delay is a function of the determined propagation delay. In such a method, the determined propagation delay may be a function of a transmission path from the mobile device to the serving antenna or from the serving antenna to the mobile device. In additional embodiments, the method may include the step of iteratively repeating step 630 and averaging the determined locations over the several iterations. In an alternative embodiment, step 650 may include determining cable delay and/or radio frequency component delay. In an alternative embodiment, the method may include the step of determining a location of one or more other mobile devices using respective received satellite information, whereby step 650 would include determining transmission delay as a function of the determined locations of the one or more other mobile devices to minimize bias from any single location determination.

While the discussion above has referenced certain exemplary networks such as UMTS networks, the disclosure herein should not be so limited. For example, the principles discussed herein are equally applicable to other networks such as, but not limited to, a TDMA network, CDMA network, a WiMax network, a WiFi network, networks utilizing EDVO, a CDMA2000 network, and 1×RTT standards or another equivalent networks or other networks that may include a system clock or equivalent. Such exemplary system clocks may thus be utilized by embodiments of the present subject matter to determine timing relationships relevant herein.

The present disclosure may be implemented by a general purpose computer programmed in accordance with the principals discussed herein. It may be emphasized that the above-described embodiments, particularly any “preferred” or exemplary embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present subject matter. Many variations and modifications may be made to the above-described embodiments of the present subject matter without departing substantially from the spirit and principles of the present subject matter. All such modifications and variations are intended to be included herein within the scope of this present subject matter.

Embodiments of the subject matter and the functional operations described herein may be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Embodiments of the subject matter described herein may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible program carrier for execution by, or to control the operation of, data processing apparatus. The tangible program carrier may be a computer readable medium. The computer readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, or a combination of one or more of them.

The term “processor” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The processor may include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program may be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described herein may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more data memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer may be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, to name just a few.

Computer readable media suitable for storing computer program instructions and data include all forms data memory including nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subject matter described herein may be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user may provide input to the computer. Other kinds of devices may be used to provide for interaction with a user as well; for example, input from the user may be received in any form, including acoustic, speech, or tactile input.

Embodiments of the subject matter described herein may be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user may interact with an implementation of the subject matter described herein, or any combination of one or more such back end, middleware, or front end components. The components of the system may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet.

The computing system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

While this description may contain many specifics, these should not be construed as limitations on the scope thereof, but rather as descriptions of features that may be specific to particular embodiments. Certain features that have been heretofore described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and may even be initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings or figures in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products.

The present subject matter may thus provide a method and system for determining the delay in the transmission path to allow for appropriate deployments of an exemplary OTDOA system.

As shown by the various configurations and embodiments illustrated in FIGS. 1-6, various embodiments for autonomous transmit chain delay measurements have been described.

While preferred embodiments of the present subject matter have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence, many variations and modifications naturally occurring to those of skill in the art from a perusal hereof.

Claims

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:

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.