Patent Description:
Coordinated multipoint (CoMP) systems are being studied as an enhanced multiple input multiple output (MIMO) technique to increase performance, especially at the cell edge, within the evolution of Long-Term Evolution Advanced (LTE-A) for Release <NUM> or beyond. However, there are some challenges for user equipment (UE) positioning within CoMP scenarios. <CIT> describes a method in a user equipment for performing positioning measurement comprises receiving positioning assistance data from a positioning node. The positioning assistance data comprises a plurality of reference cells, wherein each reference cell may be associated with at least one respective frequency, and a set of neighbor cells comprising at least one neighbor cell. The method further comprises, for each reference cell comprised in the plurality of reference cells, identifying a respective associated set of neighbor cells, wherein the reference cell and the respective associated set of neighbor cells define a group. <CIT> describes a mobile device and/or other suitable device that can utilize positioning assistance messages received from a location server, a serving network cell, and/or other entities, to assist in position fixing based on reference signals (e.g., positioning reference signals (PRSs)) detected from nearby network cells. <NPL> discusses E-UTRA OTDOA measurement requirements and relevant effects of test times for RSTD measurements.

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

Various operations may be described as multiple discrete actions or operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed and/or described operations may be omitted in additional embodiments.

For the purposes of the present disclosure, the phrase "A, B, and/or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

Embodiments of the present disclosure describe the use of virtual identifiers that are associated with remote radio heads (RRHs) to facilitate measuring and/or estimating a position of a user equipment (UE) in coordinated multipoint (CoMP) systems.

<FIG> schematically illustrates a communication network <NUM> in accordance with various embodiments. The communication network <NUM> (hereinafter "network <NUM>") may be a 3rd Generation Partnership Project (3GPP) long-term evolution (LTE) network (or an LTE-Advanced (LTE-A) network). The network <NUM> may include a radio access network (RAN) <NUM> such as an evolved universal terrestrial radio access network (E-UTRAN) that provides wireless communication access to user equipment (UE). The network <NUM> may further include a core network <NUM> such as an Evolved Packet Core (EPC) that performs various management and control functions of the network <NUM> and further provides a communication interface between the access networks and other networks, e.g., Internet <NUM>.

The RAN <NUM> may include various UEs, e.g., UE <NUM>. The UE <NUM> is shown generally as a cellular phone but may be a variety of different wireless communication devices employed by a user in various embodiments. The RAN <NUM> may further include a number of eNBs, e.g., eNB <NUM> and eNB <NUM>. The eNBs may coordinate and participate in various access functions of the RAN <NUM>. In particular, for example the eNBs may provide wireless communication to the UEs of the RAN <NUM>.

The eNB <NUM> may be part of a coordinated multipoint (CoMP) system <NUM> that further includes a plurality of RRHs, e.g., RRH <NUM>, RRH <NUM>, and RRH <NUM>. The RRHs may provide remote transmission/reception capabilities to the eNB <NUM>. The RRHs may be communicatively coupled with the eNB <NUM> through high-speed communication links, for example, fiber-optic links.

Componentsof the RAN <NUM>, for example, eNBs <NUM> and <NUM>, may be coupled with components of the core network <NUM> through an S1/S2 interface <NUM> or through some other appropriate communication interface.

The core network <NUM> may include, for example, a mobility management entity (MME) that provides control-plane signaling related to mobility and security for components of the RAN <NUM>. In various embodiments, the MME may be responsible for the tracking and paging of UEs within the RANs. The MME may be the termination point of the Non-Access Stratum (NAS). The MME may support an S1 interface with eNBs of the RAN <NUM> and an S11 interface with a serving gateway (S-GW) <NUM> of the core network <NUM>. While various specific interfaces are discussed herein, it will be understood that suitable variances may be made within the scope of the described embodiments.

The S-GW may provide user-plane signaling to transport IP data traffic between the UEs and external networks, e.g., the Internet. In <FIG>, the MME and the S-GW may be combined in MME/S-GW <NUM>.

The S-GW may be logically connected with another gateway, e.g., packet data network gateway (P-GW) <NUM>. The P-GW <NUM> may also provide user-plane signaling and may serve as a point of interconnect between the core network <NUM> and other packet data networks (PDNs).

The core network <NUM> may further include a location-based services (LBS) server <NUM>. The LBS server <NUM> may be coupled with other components of the core network <NUM> such as, for example, MME/S-GW <NUM>, and may operate to determine locations of, and provide location-based services to, UEs disposed in the various RANs of network <NUM>. The location-based services may include services such as, but not limited to, emergency services, advertising/marketing services, mapping services, etc. In some embodiments, the LBS server <NUM> may provide UEs of various RANs with information regarding positioning reference signal (PRS) configurations of assistance data reference and neighbor cells. This may facilitate the positioning measurements conducted by the UEs.

While certain of the components of the core network <NUM> are shown together, for example, the MME/S-GW <NUM>, and others are shown separately, for example, the P-GW <NUM>, it is to be understood that various modifications may be made within the scope of the embodiments of the present disclosure. For example, the MME and the S-GW may be disposed in separate devices, the P-GW and the S-GW may be disposed in one device, etc..

As discussed above, CoMP systems may improve various performance metrics of network communication; however, in the realm of positioning measurements, present CoMP systems may inject ambiguity. This may be due to current positioning measurement operations being based on parameters that are identified by a cell ID of reference cell and neighbor cells. A UE performing positioning measurements based on PRSs transmitted from RRHs having a common cell ID may distort positioning measurements such as observed time difference of arrival (OTDOA), enhanced cell ID (ECID), etc. Therefore, embodiments of the present disclosure introduce the use of virtual identifiers that are associated with the various RRHs to improve the accuracy and reliability of positioning measurements performed by UEs served by, or neighbors to, CoMP-system cells.

<FIG> is a diagram <NUM> of a message flow between various components of the network <NUM> described above with respect to <FIG>. The LBS server <NUM> may provide neighbor cell information, for example, information about eNB <NUM>, to the UE <NUM> in a neighbor cell IE, for example, an OTDOA-NeighborCellInfoListIE. <FIG> illustrates an OTDOA-NeighborCellInfoListIE <NUM> in accordance with some embodiments. The OTDOA-NeighborCellInfoListIE <NUM> may include a list of positioning parameters of a number of neighbor cells. In some embodiments, the list may be arranged in a decreasing order of priority for measurement to be performed by a target device, with the first cell in the list being the highest priority for measurement. Other embodiments may include other list sortings. The target device may provide the available measurements in an order that corresponds to the sorting of the list within the OTDOA-NeighborCellInfoListIE <NUM>.

The OTDOA-NeighborCellInfoListIE <NUM> may include a virtual RRH identifier, virtualRRHID, that corresponds to each RRH in the list of neighbor cells. The virtualRRHID may be an integer value that uniquely identifies an RRH from other RRHs associated with a common eNB. The virtualRRHID may be used to encode and decode a PRS transmitted by a corresponding RRH. The OTDOA-NeighborCellInfoListIE <NUM> may further include other positioning parameters such as, but not limited to, a cell identifier of the neighbor cell, PRS-info (for example, antenna port configuration, slot number offset, PRS subframe offset, etc.).

The LBS server <NUM> may provide assistance data reference cell information, for example, information about a cell provided by eNB <NUM>, to the UE <NUM> in an OTDOA-ReferenceCellInfoIE. <FIG> illustrates an OTDOA-ReferenceCellInfoIE <NUM> in accordance with some embodiments. The OTDOA-ReferenceCellInfoIE <NUM> may include a list of positioning parameters of a reference cell, which may or may not be a serving cell of the UE. Similar to the OTDOA-NeighborCellInfoListIE <NUM>, OTDOA-ReferenceCellInfoIE <NUM> may include one or more virtualRRHIDs that respectively correspond to RRHs of the reference cell, for example, a cell provided by CoMP system <NUM>.

The OTDOA-NeighborCellInfoList and OTDOA-ReferenceCellInfoIEs may be disposed in an LTE positioning protocol (LPP) message generated by the LBS server <NUM>. The LBS server <NUM> may transmit the LPP message to the UE <NUM>. In some embodiments, generation and/or transmission of the LPP message may be performed by upper layers such as an LPP layer within the LBS server <NUM>.

In some embodiments, the LBS server <NUM> may provide the LPP message to the MME/S-GW <NUM>, which may package the LPP message as a NAS message and deliver it to the eNB <NUM>. Upon receipt, the eNB <NUM> may package the LPP message as a radio resource control (RRC) message and deliver it to the UE <NUM>.

In various embodiments, the LBS server 152may also transmit LPP messages to the eNBsof the reference and neighbor cells to enable subsequent generation and transmission of PRSs from the various transmission points of the RAN <NUM>.

Upon receiving the LPP message, the UE <NUM> may configure positioning measurement circuitry with the positioning parameters of the LPP message. Thereafter, the UE <NUM> may be capable of processing PRSs received from various transmission points of the RAN <NUM>. For example, the UE <NUM> may receive a PRS from a neighboring eNB, for example, eNB <NUM>, and from RRHs <NUM> and <NUM>. Upon receiving the PRSs, the UE may perform positioning measurements, for example,reference signal time difference (RSTD), based on the PRSs, with the resulting positioning measurement data (e.g., RSTD data) reported, in a measurement report, to an enhanced serving mobile location center (ESMLC) in the eNB <NUM>, for example. The ESMLC may use these RSTDs, and knowledge of the locations of the transmission points (e.g., the RRHs and eNBs) within the RAN <NUM>, to estimate a location of the UE <NUM>.

In some embodiments, the UE <NUM> may perform at least preliminary location estimates based on the positioning measurements and transmit the estimates in the measurement report.

<FIG> illustrates various components of the network <NUM> in further detail in accordance with some embodiments of the present disclosure. For example, the UE <NUM> is shown with configuration circuitry <NUM> coupled with positioning measurement circuitry <NUM>. Both the configuration circuitry <NUM> and the positioning measurement circuitry <NUM> may be coupled with a wireless transceiver <NUM> that is configured to facilitate over the air communication via one or more antennas <NUM>.

The RRH <NUM> may include control circuitry <NUM> coupled with a wireless transceiver <NUM> and further coupled with a remote radio transceiver <NUM>. The wireless transceiver <NUM> may be configured to facilitate over the air communication with the UE <NUM> via one or more antennas <NUM> of the RRH <NUM>. The remote radio transceiver <NUM> may be configured to communicate with the eNB <NUM> over a high-speed communication link, for example, a fiber-optic link. The control circuitry <NUM> may be responsible for various transmission/reception operations. In some embodiments, the control circuitry <NUM> may generate and transmit PRSs to UEs of the RAN <NUM>.

The eNB <NUM> may include control circuitry <NUM> coupled with a remote radio transceiver <NUM> and a communication transceiver <NUM>. The remote radio transceiver <NUM> may be configured to facilitate communication with the RRH <NUM> over the high-speed communication link. Similarly, the communication transceiver <NUM> may be configured to facilitate communication with one or more elements of the core network <NUM> such as, for example, LBS server <NUM>. The control circuitry <NUM> may control various communication aspects of the RAN <NUM> including, for example, operation of the RRHs of the CoMPsystem <NUM>. In some embodiments, the control circuitry <NUM> may include an ESMLC that may be used for various positioning services such as, but not limited to, forwarding the LPP message to the UE <NUM>, receiving the measurement report, and estimating a location of the UE <NUM>.

The LBS server <NUM> may include control circuitry <NUM> that may be configured to perform various LPP-layer operations. The control circuitry <NUM> may be coupled with a communication transceiver <NUM> and may be configured to perform various positioning and location-based services.

The communication links, shown generally as block bidirectional arrows in <FIG>, may be direct or indirect communication links. For example, the high-speed communication link coupling the RRH <NUM> with the eNB <NUM> may be a direct communication link; while the communication link coupling the eNB <NUM> with the LBS server <NUM> may be an indirect communication link that includes, for example, MME/S-GW <NUM>.

Referring also to <FIG>, the control circuitry <NUM> may determine a virtual identifier associated with RRH <NUM>. This determination may be as a result of the virtual identifier being generated locally by the LBS server <NUM> and assigned to the RRH or, alternatively, the LBS server <NUM> may be provided with an indication of the virtual identifier from another component in the network <NUM>. The control circuitry <NUM> may then generate an LPP message that includes, among other positioning parameters, an indication of the virtual identifier. The control circuitry <NUM> may then transmit the LPP message via the communication transceiver <NUM> to the UE <NUM>.

The eNB <NUM> may receive the LPP message from the LBS server <NUM> via the communication transceiver <NUM>. The control circuitry <NUM> may then configure various RRHs controlled by the eNB <NUM> with appropriate positioning parameters such as, but not limited to, virtual RRH IDs. With respect to RRH <NUM>, the eNB <NUM> may transmit the LPP message to the RRH <NUM> via the remote radio transceiver <NUM>. The LPP message may also be transmitted to the UE <NUM> by the RRH <NUM>, the eNB <NUM>, or another RRH.

In some embodiments, the control circuitry <NUM> may configure PRS bandwidth, for example the number of resource blocks used for transmission of a PRS signal, and the period at which a PRS is transmitted.

The control circuitry <NUM> of the RRH <NUM> may receive the LPP message from the eNB <NUM> via the remote radio transceiver <NUM>. The control circuitry <NUM> may store the positioning parameters, including the virtual RRH ID, for later generation of PRSs.

The control circuitry <NUM> may include apseudo-random sequence generator (PRSG) <NUM> and a reference signal generator (RSG) <NUM>. The PRSG <NUM> may be initialized with an initialization sequence based on the virtual identifier of the RRH <NUM> to generate a pseudo-random sequence. In some embodiments, the initialization sequence may be defined by: <MAT> where nsis a number of a slot within a radio frame, l is an orthogonal frequency division multiplexing (OFDM) symbol number within the slot, <MAT> is a function of a cell identifier, <MAT>, and the first virtual identifier, <MAT>, and <MAT>.

In some embodiments, the pseudo-random sequence may be defined by a link-<NUM> Gold sequence. The output sequence c(n) of length MPN, where n = <NUM>, <NUM>,. , MPN-<NUM>, is defined by: <MAT> where Nc = <NUM> and the first m-sequence may be initialized with x<NUM>(<NUM>) = <NUM>, x<NUM>(n) = <NUM>, n = <NUM>, <NUM>,. Initialization of the second m-sequence may be denoted by <MAT> with the value depending on the application of the sequence.

The pseudo-random sequence c(n) generated by the PRSG <NUM> may be provided to the RSG <NUM>, which may generate a PRS based on the pseudo-random sequence. In some embodiments, the PRS may be defined in the physical layer by: <MAT>.

The control circuitry <NUM> may transmit the PRS via the wireless transceiver <NUM> according to the PRS bandwidth and periodicity configurations provided by the eNB <NUM>. In some embodiments, the PRS may be transmitted on antenna port <NUM> using a configurable number of consecutive subframes.

In some embodiments, some or all of the functions of the control circuitry <NUM> may be employed in control circuitry <NUM>. In such embodiments, the RRH <NUM> may be used primarily for operations provided by wireless transceiver <NUM> and antennas <NUM>.

The configuration circuitry <NUM> of the UE <NUM> may receive the LPP message from the eNB <NUM>, for example. The configuration circuitry <NUM> may configure the positioning parameters based on the LPP message.

The positioning measurement circuitry <NUM> may observe the PRS sent from the RRH <NUM> (and other transmission points in the RAN <NUM>). Observation of the PRS sent from the RRH <NUM> may be facilitated by prior configuration of the positioning parameters including the virtual RRH ID. This may allow the positioning measurement circuitry <NUM> to uniquely identify a PRS as coming from RRH <NUM> as opposed to coming from RRH <NUM>, for example. The positioning measurement circuitry <NUM> may perform measurements based on the observed PRSs. In various embodiments, the measurements may include, but are not limited to, OTDOA measurements such as RSTD.

The positioning measurement circuitry <NUM> may then generate a measurement report and transmit the measurement report to an eNB of a serving cell, for example, eNB <NUM>.

As discussed above, in some embodiments, the positioning measurement circuitry <NUM> may simply perform measurements based on the PRSs with the measurement results being fed back to the eNB. At that point, the eNB may estimate a location of the UE. In other embodiments, the positioning measurement circuitry <NUM> may perform at least preliminary estimations of the UE location.

Transmitting PRSs from RRHs based on virtual identities of the RRHs may facilitate positioning operations in a number of ways. For example, a UE with knowledge of the virtual IDs of the RRHs may be capable of identifying the individual PRSs with less interference from other PRSs. Further, the measurement results may be associated with a higher degree of accuracy given that a larger number of distinct PRSs may be used in the calculations.

A UE, RRH, eNB,and/or LBS server as described herein may be implemented into a system using any suitable hardware and/or software to configure as desired. <FIG> illustrates, for one embodiment, an example system600 comprising interface circuitry <NUM> (which may include radio frequency (RF) circuitry <NUM> and baseband circuitry <NUM> in some embodiments), application circuitry <NUM>, memory/storage <NUM>, display <NUM>, camera <NUM>, sensor <NUM>, and input/output (I/O) interface <NUM>, coupled with each other at least as shown.

The application circuitry <NUM> may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors may be coupled with memory/storage <NUM> and configured to execute instructions stored in the memory/storage <NUM> to enable various applications and/or operating systems running on the system <NUM>.

Interface circuitry <NUM> may include circuitry such as, but not limited to, one or more single-core or multi-core processors designed to provide suitable communication interfaces for respective device and networking applications. While the interface circuitry <NUM> is shown in <FIG> with baseband and RF circuitry, these components may not be included in a device that does not participate directly in wireless transmission/reception.

The processor(s) may include a baseband processor. The baseband circuitry <NUM> may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry <NUM> may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry <NUM> may support communication with an E-UTRAN and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), or a wireless personal area network (WPAN).

In various embodiments, baseband circuitry <NUM> may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry <NUM> may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the RF circuitry <NUM> may include switches, filters, amplifiers, etc., to facilitate the communication with the wireless network.

In various embodiments, RF circuitry <NUM> may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry <NUM> may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In some embodiments, some or all of the constituent components of the baseband circuitry <NUM>, the application circuitry <NUM>, and/or the memory/storage <NUM> may be implemented together on a system on a chip (SOC).

In an embodiment in which the system <NUM> represents an eNB, for example, eNB <NUM>, the remote radio transceiver <NUM>, the communication transceiver <NUM>, and the control circuitry <NUM> may be implemented in the interface circuitry <NUM> and/or application circuitry <NUM>.

In an embodiment in which the system <NUM> represents a UE, for example, UE <NUM>, the configuration circuitry <NUM>, positioning measurement circuitry <NUM>, and/or wireless transceiver <NUM> may be implemented in the RF circuitry <NUM>, the baseband circuitry <NUM>, and/or the application circuitry <NUM>.

In an embodiment in which the system <NUM> represents anRRH, for example, RRH <NUM>, the control circuitry <NUM>, the wireless transceiver <NUM>, and the remote radio transceiver <NUM> may be implemented in the interface circuitry <NUM> and/or the application circuitry <NUM>.

In an embodiment in which the system <NUM> represents an LBS server, for example, LBS server <NUM>, the control circuitry <NUM> and the communication transceiver <NUM> may be implemented in the application circuitry <NUM> and/or the interface circuitry <NUM>.

Memory/storage <NUM> may be used to load and store data and/or instructions, for example, for system <NUM>. Memory/storage <NUM> for one embodiment may include any combination of suitable volatile memory (e.g., dynamic random access memory (DRAM)) and/or non-volatile memory (e.g., Flash memory).

In various embodiments, the I/O interface <NUM> may include one or more user interfaces designed to enable user interaction with the system600 and/or peripheral component interfaces designed to enable peripheral component interaction with the system600. User interfaces may include, but are not limited to, a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments,sensor628 may include one or more sensing devices to determine environmental conditions and/or location information related to the system600. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry608 and/or RF circuitry604 to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

In various embodiments, the display620 may include a display (e.g., a liquid crystal display, a touch screen display, etc.).

Claim 1:
A method performed by one or more device processors in a cellular communications network, the method comprising:
receiving, by a user equipment, UE, in the cellular communications network, a positioning protocol message that includes an observed time difference of arrival, OTDOA cell information list data information element, the information element, IE including a cell identifier of a cell in the cellular communications network and virtual identifiers of one or more transmission points, TPs, in the cellular communications network, the virtual identifiers associating the one or more TPs with the cell;
receiving, by the UE, a positioning reference signal, PRS from a first TP of the one or more TPs, wherein the PRS is generated using an initialization sequence that is based on at least the virtual identifier of the first TP and the cell identifier of the cell, a slot number within a radio frame, an OFDM symbol number within the slot, and one of a normal cyclic prefix, CP or an extended CP corresponding to the OFDM symbol;
obtaining, by the UE from the IE in the positioning protocol message, the cell identifier and the virtual identifier of the first TP; and
processing, by the UE, the PRS using the cell identifier and the virtual identifier of the first TP obtained from the IE in the positioning protocol message.