Patent ID: 12232122

DETAILED DESCRIPTION

A network based trilateration solution, where the uplink transmission of the terminal is measured by at least three different measurement unit having an accurate time reference, offers reasonably good accuracy in city areas where the cell sizes are small and the uplink transmission may be detected by multiple measurement units (typically co-located with or even integrated to base stations). Thus, a hybrid solution combining multiple positioning techniques (e.g., network based trilateration and GPS) may meet the FCC emergency call requirements.

Uplink time difference of arrival (U-TDOA) is based on the reception of a transmission from a terminal by multiple sites (regardless of possible macro-diversity). In some systems, a signal processing means may be used to dig out the signal from the interference (e.g., using post-processing). There are a number of potential interference sources, for example other mobile devices.

In UTRAN LTE and SC-FDMA systems, an uplink resource may be controlled by one cell. The uplink resource allocation may vary both in time and frequency domains, e.g., a locationing measurement unit (LMU) may have difficulties in detecting signals from terminals. This may be due to: 1) There is no similar user identification based on the spreading (scrambling) code; and/or 2) There is no information outside the serving cell which allocated resources to the UE. Thus, the lack of proper information complicates the task of making location measurements.

In order to provide cellular network based trilateration positioning technique to a specific radio access technology two problems need to be overcome: 1) the uplink transmission characteristics of the terminal being positioned need to be known in advance by the participating LMUs; and 2) at least three LMUs must be able to detect the signal of the terminal being positioned and measure the received signal timing relative to a common (and accurate) time reference (e.g., a GPS time).

Based on the received time differences and the known locations of the LMUs the location of the terminal being positioned may be calculated.

Exemplary embodiments in accordance with this invention are related to the use of an uplink time difference of arrival (U-TDOA) location positioning method, for example as a part of eUTRAN. The U-TDOA may be based on an uplink measurements made in coordination with LMUs. Exemplary embodiments in accordance with this invention may make use of U-TDOA with uplink multiple access, e.g., SC-FDMA. Additionally, exemplary embodiments in accordance with this invention may be used in cooperation with enhanced observed time difference (E-OTD) techniques.

Before describing in further detail the exemplary embodiments of this invention, reference is made toFIG.2for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention.

InFIG.2a wireless network235is adapted for communication over a wireless link232with an apparatus, such as a mobile communication device which may be referred to as a UE210, via a network access node, such as a Node B (e.g., a base station), and more specifically an eNB220. The network235may include a network control element (NCE)240that may include the MME/S GW functionality shown inFIG.1, and which provides connectivity with a network235, such as a telephone network and/or a data communications network (e.g., the internet).

The UE210includes a controller, such as a computer or a data processor (DP)214, a computer-readable memory medium embodied as a memory (MEM)216that stores a program of computer instructions (PROG)218, and a suitable radio frequency (RF) transceiver212for bidirectional wireless communications with the eNB220via one or more antennas.

The eNB220also includes a controller, such as a computer or a data processor (DP)224, a computer-readable memory medium embodied as a memory (MEM)226that stores a program of computer instructions (PROG)228, and a suitable RF transceiver222for communication with the UE210via one or more antennas. The eNB220is coupled via a data/control path234to the NCE240. The path234may be implemented as the S1 interface shown inFIG.1. The eNB220may also be coupled to another eNB via data/control path236, which may be implemented as the X2 interface shown inFIG.1.

The NCE240includes a controller, such as a computer or a data processor (DP)244, a computer-readable memory medium embodied as a memory (MEM)246that stores a program of computer instructions (PROG)248.

At least one of the PROGs218,228and248is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail.

That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP214of the UE210; by the DP224of the eNB220; and/or by the DP244of the eNB240, or by hardware, or by a combination of software and hardware (and firmware).

The UE210and the eNB220may also include dedicated processors, for example processors215and processors225.

In general, the various embodiments of the UE210can include, but are not limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The computer readable MEMs216,226and246may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs214,224and244may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples.

FIG.3illustrates further detail of an exemplary UE in both plan view (left) and sectional view (right), and the invention may be embodied in one or some combination of those more function-specific components. AtFIG.3the UE210has a graphical display interface320and a user interface322illustrated as a keypad but understood as also encompassing touch-screen technology at the graphical display interface320and voice-recognition technology received at the microphone324. A power actuator326controls the device being turned on and off by the user. The exemplary UE210may have a camera328which is shown as being forward facing (e.g., for video calls) but may alternatively or additionally be rearward facing (e.g., for capturing images and video for local storage). The camera328is controlled by a shutter actuator330and optionally by a zoom actuator332which may alternatively function as a volume adjustment for the speaker(s)334when the camera328is not in an active mode.

Within the sectional view ofFIG.3are seen multiple transmit/receive antennas336that are typically used for cellular communication. The antennas336may be multi-band for use with other radios in the UE. The operable ground plane for the antennas336is shown by shading as spanning the entire space enclosed by the UE housing though in some embodiments the ground plane may be limited to a smaller area, such as disposed on a printed wiring board on which the power chip338is formed. The power chip338controls power amplification on the channels being transmitted and/or across the antennas that transmit simultaneously where spatial diversity is used, and amplifies the received signals. The power chip338outputs the amplified received signal to the radio-frequency (RF) chip340which demodulates and downconverts the signal for baseband processing. The baseband (BB) chip342detects the signal which is then converted to a bit-stream and finally decoded. Similar processing occurs in reverse for signals generated in the apparatus210and transmitted from it.

Signals to and from the camera328pass through an image/video processor344which encodes and decodes the various image frames. A separate audio processor346may also be present controlling signals to and from the speakers334and the microphone324. The graphical display interface320is refreshed from a frame memory348as controlled by a user interface chip350which may process signals to and from the display interface320and/or additionally process user inputs from the keypad322and elsewhere.

Certain embodiments of the UE210may also include one or more secondary radios such as a wireless local area network radio WLAN337and a Bluetooth® radio339, which may incorporate an antenna on-chip or be coupled to an off-chip antenna. Throughout the apparatus are various memories such as random access memory RAM343, read only memory ROM345, and in some embodiments removable memory such as the illustrated memory card347. The various programs218are stored in one or more of these memories. All of these components within the UE210are normally powered by a portable power supply such as a battery349.

The processors338,340,342,344,346,350, if embodied as separate entities in a UE210or eNB220, may operate in a slave relationship to the main processor214,224, which may then be in a master relationship to them. Any or all of these various processors ofFIG.3access one or more of the various memories, which may be on-chip with the processor or separate therefrom. Similar function-specific components that are directed toward communications over a network broader than a piconet (e.g., components336,338,340,342-345and347) may also be disposed in exemplary embodiments of the access node220, which may have an array of tower-mounted antennas rather than the two shown atFIG.3.

Note that the various chips (e.g.,338,340,342, etc.) that were described above may be combined into a fewer number than described and, in a most compact case, may all be embodied physically within a single chip.

In an exemplary embodiment in accordance with this invention, an eNode B sends (e.g. via the LE) information to an LMU regarding a resource pattern (e.g., in time, frequency and/or code domains) for a particular terminal. Alternatively, the LMU may be given the time slots when the terminal scheduled. The LE may use this information to coordinate additional LMUs for determining the location of the terminal.

When an eNB is made aware of the fact that a particular terminal is being positioned, for example by a locating entity (LE), the eNB orders the terminal to transmit a signal with assigned time and frequency characteristics (e.g., TTI, etc.). The signal characteristics the eNB assigns the terminal are also made known to LMUs trying to position the terminal.

In addition the eNB could instruction the terminal to boost the uplink transmission power in order to increase the probability that a sufficiently large number of LMUs detect and measure the timing of the terminal's uplink transmission.

A central entity, such as a locationing entity (LE) (e.g., a locationing server) instructs an eNB serving a terminal to be located to instruct the terminal to start transmitting a signal used in location measurements. The LE informs at least three LMUs to start seeking for and, if detected, measure the receive timing of the signal. The LMUs will report the measurements (e.g., the received timing relative to a common time reference, for example, GPS time) to a location calculation entity (e.g., the LE). The locations of the LMUs may be known and thus the position of the terminal being located can be calculated based on the time difference of the terminal's signal as observed by the LMUs.

Signal characteristics to be used for the signal to be detected by the LMUs may be pre-negotiated, assigned from the LE, or decided by the serving eNB and subsequently informed (e.g. via the LE) to the LMUs.

The resources (e.g., time-frequency resources) to use for positioning may be to communicate the parameters used in the configuration of the SRS or PRACH (using dedicated RRC signaling, broadcast signaling, etc.). If positioning based on a dynamically scheduled PUSCH or DM RS transmission is used, the exact frequency allocation, subframes as well as the DM RS cyclic shift may be signaled explicitly or use a predetermined value, in addition to the relevant serving eNB related parameters which may include, e.g., cell identity and parameters related to DM RS sequence group hopping, sequence hopping and sequence-shift pattern. The signaling of the parameters between eNBs could be done over the X2 air interface or via the backhaul network.

The serving eNB may command a UE to transmit a signal that is detectable, occurs relatively often and is of sufficient energy and duration for the LMUs to detect and measure its timing. That may be done by using uplink sounding reference symbols (UL SRS), which may be ordered to be sent periodically over a specific time duration sufficient for the LMUs to measure. Periodic UL SRS may be commanded on once, and off once, between these commands the terminal may autonomously transmit using known time and frequency characteristics. Alternatively, the eNB may indicate a duration for the transmission, avoiding transmitting an off command later.

If needed, the eNB could configure UL SRSs or simply turn UL SRSs off for other UEs in order to release sufficient UL SRS resources for the positioning. The UL SRS resources for the positioning may also be pre-determined.

Another possibility may be the usage of a dedicated PRACH preamble. The eNB may repeatedly order the UE to transmit a dedicated PRACH preamble on a PRACH channel (or channels). The eNB would send the dedicated PRACH preamble orders to the UE at times known to the LMUs. Also, other dedicated preamble parameters could be pre-negotiated with other LMUs (e.g., during initial setup).

The terminal may instead be scheduled to transmit a message at a predetermined time and frequency location. This message may include scheduling information or some other useful information, e.g., an aperiodic CQI report, a Buffer status report (BSR), a demodulation reference signal (DM RS) of a PUSCH transmission, etc.

In another exemplary embodiment in accordance with this invention, a new signal type could be defined for the locationing signal, e.g., on a pre-determined set of sub-frequency/frequencies. The signal could also be an existing signal that is reserved or re-defined solely for positioning. For example, the UE could send, when ordered, a predetermined PRACH preamble at a predetermined PRACH format using predetermined frequency resources and periodicity over a specific time duration. The relevant parameters could be predetermined relative to the PRACH parameters of the cell or assigned in a signal using absolute terms. A combination of the signaling mechanisms could also be utilized: e.g. with dedicated PRACH preambles and wideband SRS transmission allowing for a precise positioning estimate. Further, angle, or direction of arrival measurement of the UE signal at the LMU could also be utilized as a way to improve the positioning accuracy. This measurement could be used either alone or as a complementary mechanism with the U-TDOA methods to further improve positioning accuracy.

Semi-persistent scheduling (SPS) which defines a deterministic time and frequency transmission pattern may be used by the uplink transmission.

The serving eNB could also boost the uplink transmission power of the transmitted signal to enhance the probability that at least three LMUs can detect the signal. The uplink power control commands under the eNBs discretion may be used for this purpose.

FIG.4illustrates a simplified diagram of a location determining system400which includes various exemplary electronic devices that are suitable for use in practicing the exemplary embodiments of this invention. As shown, UE210is the mobile device which is having its location determined. LMUs410,420and430(some of which may be integrated into eNBs) may detect signals in their respective areas (LMU410in area415, LMU420in area425, and LMU430in area435). As show, UE210may transmit a signal which may be detected by LMUs410,420and430. LMUs410,420and430may send the detected signal (and additional information, e.g., the location information for the LMU) to LE440. LE440may be part of a LMU (including LMUs410,420and430), an eNB, an MME, etc.

FIG.5depicts a simplified transmission diagram of an exemplary embodiment of this invention. As shown, UE210is served by eNB220. At time510, LE440instructs the eNB220to order the UE210to transmit a signal for LCS. These instructions may include an assignment of signal characteristics. Alternatively, eNB may determine the signal characteristics for the signal and inform the LE accordingly (not shown).

At time520, the eNB220transmit orders to the UE210. These orders may include an assignment of signal characteristics (e.g., specific parameters, reference to a predetermined signal characteristics, etc.).

At time530, the LE440instructs at least three LMUs (e.g.,410,420,430) to search for a signal from the UE210. These instructions may include the assigned signal characteristics.

Additionally, eNB220may also search for the signal from the UE210(e.g., using an LMU located in eNB220). The signaling performed at times520and530may occur in any timed order (e.g.,530may occur before520).

In response to receiving orders the UE210begins transmitting a signal at time540. If signal characteristics are provided, then the signal may conform to those characteristics. LMU1410, LMU2420. . . LMUn430(and even eNB220) may then detect the signal from UE210. Upon receiving the signal, the associated LMU may determine a U-TDOA based upon the assigned transmit time and the time of reception.

At time550, LMU1410, LMU2420. . . LMUn430(and even eNB220) transmit information regarding the received signal (e.g., the U-TDOA information) to the LE440. Additional location information or LMU identifying information may be sent at this time. Based upon the received signal information, the LE440may determine the location of the UE210(e.g., using geometric triangulation, A-FLT, etc.). Alternatively, a separate device may receive this information and determine the location of the UE210.

Based on the foregoing it should be apparent that the exemplary embodiments of this invention provide a method, apparatus and computer program(s) to determining location information for a wireless device.

FIG.6is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention. In accordance with these exemplary embodiments a method performs, at block610, instructions comprising an indication of signal characteristics of a locating signal from a first device (e.g., UE210) are sent to a plurality of signal receiving devices (e.g., LMU1410, LMU2420, LMUn430, etc.). Locating signal information is received from at least three of the signal receiving devices at block620. At block630, a location of the first device is determined based at least in part on the received locating signal information. Additionally, the location may be determined at least in part on the signal characteristics (e.g., allocated time domain characteristics). The location of the first device is output at block640.

FIG.7is a logic flow diagram that illustrates the operation of another method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention. In accordance with these exemplary embodiments a method performs, at block710, instructions comprising an indication of signal characteristics of a locating signal from a first device (e.g., UE210) are received. The locating signal from the first device is received at block720. At block730, locating signal information based at least in part on the received locating signal is determined. Additionally, the location may be determined at least in part on the signal characteristics (e.g., allocated time domain characteristics). The locating signal information is sent to a second device (e.g., LE440) at block740.

The various blocks shown inFIGS.6and7may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s).

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this invention.

For example, while the exemplary embodiments have been described above in the context of the EUTRAN (UTRAN-LTE) system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system, and that they may be used to advantage in other wireless communication systems such as for example (UTRAN, GSM, WCDMA, etc.).

It should be noted that the terms “connected,” “coupled,” or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are “connected” or “coupled” together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be “connected” or “coupled” together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples.

Further, the various names used for the described parameters (e.g., CQI, etc.) are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. Further, the formulas and expressions that use these various parameters may differ from those expressly disclosed herein. Further, the various names assigned to different channels (e.g., PRACH, etc.) are not intended to be limiting in any respect, as these various channels may be identified by any suitable names.

Furthermore, some of the features of the various non-limiting and exemplary embodiments of this invention may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.