Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/0202—Channel estimation
  • H04L25/0212—Channel estimation of impulse response
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
  • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0205—Details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0205—Details
  • G01S5/0218—Multipath in signal reception
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0273—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves using multipath or indirect path propagation signals in position determination
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/0202—Channel estimation
  • H04L25/0224—Channel estimation using sounding signals
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/10—Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements, e.g. omega or decca systems

Definitions

• This disclosure relates to a 5G new radio (NR) mobile communication system and to options for accurate-to-extremely-accurate localization and positioning solutions in such a system, but it is not limited to such a system.
• NR new radio
• Fischer “Observed Time Difference of Arrival (OTDOA) Positioning in 3GPP LTE”, Qualcomm Technologies, Inc., June 6, 2014, Fischer provided an overview of the OTDOA concept as it is being standardized for 3GPP LTE. In particular, Fischer gives the limits of OTDOA to a best-case location accuracy of 32 ns, which, again, is equivalent to about ⁇ 5 m.
• gNB should be understood to mean “network node”.
• the term “gNB” is used to denote a network node in 5G.
• the present invention as described below, is not limited to 5G, but may be applicable to future generations yet to be developed.
• gNB should be understood more broadly as a network node.
• a method comprises receiving reference signals from at least one network node; sending at least one parameter relating to a measured channel impulse response back to said at least one network node; and repeating said receiving of reference signals and said sending of said at least one parameter relating to the measured channel impulse response M times for calculation of M single-trip intervals or N round-trip intervals, M and N being integers.
• an apparatus comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform: receive reference signals from at least one network node; send at least one parameter relating to a measured channel impulse response back to said at least one network node; and repeat said receive of reference signals and said send of said at least one parameter relating to the measured channel impulse response M times for calculation of M single-trip intervals or N round-trip intervals, M and N being integers.
• an apparatus comprises means for receiving reference signals from at least one network node; means for sending at least one parameter relating to a measured channel impulse response back to said at least one network node; and means for repeating said receiving of reference signals and said sending of said at least one parameter relating to the measured channel impulse response M times for calculation of M single-trip intervals or N round-trip intervals, M and N being integers.
• a computer program product comprises a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: receiving reference signals from at least one network node; sending at least one parameter relating to a measured channel impulse response back to said at least one network node; and repeating said receiving of reference signals and said sending of said at least one parameter relating to the measured channel impulse response M times for calculation of M single-trip intervals or N round-trip intervals, M and N being integers.
• a method comprises transmitting reference signals to a network entity B from a network entity A, wherein network entity A and network entity B are each one of a network node and a user equipment; receiving a measured channel impulse response back from the network entity B after a first round-trip time interval; sending the channel impulse response back to the network entity B; receiving the channel impulse response back from the network entity B after a second round-trip time interval; repeating the preceding sending and receiving to record N round- trip time intervals, N being an integer; calculating a total time for the N round-trip intervals; and dividing the total time by N to obtain an estimate of a single round-trip time more accurate by a factor of 2N.
• an apparatus comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform: transmit reference signals to a network entity B from the apparatus, wherein the apparatus and the network entity B are each one of a network node and a user equipment; receive a measured channel impulse response back from the network entity B after a first round-trip time interval; send the channel impulse response back to the network entity B; receive the channel impulse response back from the network entity B after a second round-trip time interval; repeat the preceding send and receive to record N round-trip time intervals, N being an integer; calculate a total time for the N round-trip intervals; and divide the total time by N to obtain an estimate of a single round-trip time more accurate by a factor of 2N.
• an apparatus comprises means for transmitting reference signals to a network entity B from the apparatus, wherein the apparatus and the network entity B are each one of a network node and a user equipment; means for receiving a measured channel impulse response back from the network entity B after a first round-trip time interval; means for sending the channel impulse response back to the network entity B; means for receiving the channel impulse response back from the network entity B after a second round-trip time interval; means for repeating the preceding sending and receiving to record N round-trip time intervals, N being an integer; means for calculating a total time for the N round-trip intervals; and means for dividing the total time by N to obtain an estimate of a single round-trip time more accurate by a factor of 2N.
• a computer program product comprises a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: transmitting reference signals to a network entity B from a network entity A, wherein network entity A and network entity B are each one of a network node and a user equipment; receiving a measured channel impulse response back from the network entity B after a first round-trip time interval; sending the channel impulse response back to the network entity B; receiving the channel impulse response back from the network entity B after a second round-trip time interval; repeating the preceding sending and receiving to record N round-trip time intervals, N being an integer; calculating a total time for the N round-trip intervals; and dividing the total time by N to obtain an estimate of a single round-trip time more accurate by a factor of 2N.
• FIG. 1 shows a simplified block diagram of certain apparatus in which the subject matter of the present disclosure may be practiced.
• Figures 2 and 3 show an example of New Radio (NR) architecture having the 5G core (5GC) and the NG-RAN.
• Figure 4 illustrates the simplest implementation of the proposed ping-pong concept for a line-of-sight (LOS) link with a single MPC and for a single gNB-UE link.
• LOS line-of-sight
• Figure 5 illustrates the main effects of the radio channel on the Tx- and Rx- signals and of the UE processing.
• Figure 6 illustrates the combined retransmission of received Dirac pulses from two gNBs.
• Figure 7 illustrates the combined processing of multiple gNB signals to overcome UE baseband processing non-idealities
• Figure 8 illustrates the proposed ping-pong time estimation over multiple steps including a time-alignment process.
• Figure 9 presents a message-sequence chart for the present ping-pong positioning method.
• Figure 10 is a flow chart illustrating a method performed in accordance with one aspect of the present disclosure.
• Figure 11 is a flow chart illustrating a method performed in accordance with another aspect of the present disclosure.
• FIG. 1 is a block diagram of one possible and non-limiting example in which the subject matter of the present disclosure may be practiced.
• a user equipment (UE) 110 radio access network (RAN) node 170, and network element(s) 190 are illustrated.
• the user equipment (UE) 110 is in wireless communication with a wireless network 100.
• a UE is a wireless device, typically mobile, that can access the wireless network.
• the UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127.
• Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133.
• the one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like.
• the one or more transceivers 130 are connected to one or more antennas 128.
• the one or more memories 125 include computer program code 123.
• the UE 110 includes a module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways.
• the module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120.
• the module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array.
• the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120.
• the one or more memories 125 and the computer program code 123 may be configured, with the one or more processors 120, to cause the user equipment 110 to perform one or more of the operations as described herein.
• the UE 110 communicates with RAN node 170 via a wireless link 111.
• the RAN node 170 in this example is a base station that provides access by wireless devices, such as the UE 110, to the wireless network 100.
• the RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR).
• the RAN node 170 may be an NG-RAN node, which is defined as either a gNB or an ng- eNB.
• a gNB is a node providing NR user plane and control-plane protocol terminations toward the UE, and connected via the NG interface to a 5GC, such as, for example, the network element(s) 190.
• the ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC.
• the NG-RAN node may include multiple gNBs, which may also include a centralized unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown.
• the DU may include or be coupled to and control a radio unit (RU).
• the gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs.
• the gNB-CU terminates the FI interface connected with the gNB-DU.
• the FI interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195.
• the gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or ng-eNB, and its operation is partly controlled by gNB-CU.
• One gNB-CU supports one or multiple cells.
• One cell is supported by only one gNB-DU.
• the gNB-DU terminates the FI interface 198 connected with the gNB-CU.
• the DU 195 is considered to include the transceiver 160, for example, as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, for example, under control of and connected to the DU 195.
• the RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.
• eNB evolved NodeB
• LTE long term evolution
• the RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157.
• Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163.
• the one or more transceivers 160 are connected to one or more antennas 158.
• the one or more memories 155 include computer program code 153.
• the CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory/memories and processor(s), and/or other hardware, but these are not shown.
• the RAN node 170 includes a module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways.
• the module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152.
• the module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array.
• module 150 may be implemented as module 150-2, which is implemented as computer program code 153 executed by the one or more processors 152.
• the one or more memories 155 and the computer program code 153 are configured, with the one or more processors 152, to cause the RAN node 170 to perform one or more of the operations as described herein.
• the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.
• the one or more network interfaces 161 communicate over a network such as via the links 176 and 131.
• Two or more gNBs 170 may communicate using, e.g., link 176.
• the link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.
• the one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like.
• the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH/DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a centralized unit (CU), gNB-CU) of the RAN node 170 to the RRH/DU 195.
• Reference 198 also indicates those suitable network link(s).
• each cell performs functions, but it should be clear that equipment which forms the cell will perform the functions.
• the cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360° area so that the single base station’s coverage area covers an approximate oval or circle.
• each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120° cells per carrier and two carriers, then the base station has a total of 6 cells.
• the wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and/or a data communications network (e.g., the Internet).
• a further network such as a telephone network and/or a data communications network (e.g., the Internet).
• core network functionality for 5G may include access and mobility management function(s) (AMF(S)) and/or user plane functions (UPF(s)) and/or session management function(s) (SMF(s)).
• AMF(S) access and mobility management function(s)
• UPF(s) user plane functions
• SMF(s) session management function
• Such core network functionality for LTE may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality. These are merely exemplary functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported.
• the RAN node 170 is coupled via a link 131 to a network element 190.
• the link 131 may be implemented as, for example, an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards.
• the network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W I/F(s)) 180, interconnected through one or more buses 185.
• the one or more memories 171 include computer program code 173.
• the one or more memories 171 and the computer program code 173 are configured, with the one or more processors 175, to cause the network element 190 to perform one or more operations.
• the wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network.
• Network virtualization involves platform virtualization, often combined with resource virtualization.
• Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.
• the computer-readable memories 125, 155, and 171 may 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 computer-readable memories 125, 155, and 171 may be means for performing storage functions.
• the processors 120, 152, and 175 may 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 multi-core processor architecture, as nonlimiting examples.
• the processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, and other functions as described herein.
• the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, 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, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.
• Figures 2 and 3 show an example of New Radio (NR) architecture having the 5G core (5GC) and the NG-RAN.
• the base stations gNB are coupled to the 5GC by the interface to Core NGs, and the gNBs are coupled to each other by the inter-base stations interface Xn.
• NR New Radio
• the main idea of the present disclosure is to realize multiple back-and- forth, or ping-pong, measurements for estimating multi-path component (MPC) delays of a time-domain channel impulse response (CIR) between one or more gNBs and a UE.
• MPC multi-path component
• CIR time-domain channel impulse response
• Dt represents a deterministic limit for the measurement accuracy of the system setup without using any ping pong operation.
• it is taken to be an absolute delay value with respect to the MPC delay.
• the limited measurement accuracy may have one of a number of underlying causes, such as a delay offset between cooperating gNBs, a limited quantization of the time estimation in the UE, or, for example, the best possible resolution of the profiling delay estimation for the given SINR, and the profiling algorithm being used.
• a delay offset between cooperating gNBs such as a delay offset between cooperating gNBs, a limited quantization of the time estimation in the UE, or, for example, the best possible resolution of the profiling delay estimation for the given SINR, and the profiling algorithm being used.
• Dirac pulse 402 represented for convenience by an upstanding arrow
• the position accuracy can be improved from ⁇ 5 m to about + 0.25 m, which is one twentieth of + 5 m.
• the present disclosure is concerned with deterministic errors, such as those from delay offsets at the gNB and quantization errors of the measurement device.
• deterministic errors can be reduced by a factor of 2N.
• the UE is, in one embodiment, just receiving the signal from the gNB and retransmitting it in the next possible subframe without - or, more accurately, with minimum - processing.
• the mirror operation is without any delay estimation at the UE.
• the measurement device quantization error is assumed to be 32 ns, which is equivalent to ⁇ 5 m. This is the deterministic error.
• small deviations from the quantization raster add up to a large value, so that, after division by 2N, the final inaccuracy is reduced (ideally) by a factor of 2N.
• OTDOA Observed Time Difference of Arrival
• the synchronization level of the transmission points such as gNBs
• the present method can in fact reduce the uncertainty level of factors 1, 3, and 5 above.
• section 8.7 (“Exemplary Error Budget”) of Sven Fischer, “Observed Time Difference of Arrival (OTDOA) Positioning in 3GPP LTE”, Qualcomm Technologies, Inc., June 6, 2014, noted above, provides a nice summary.
• the benefit of the present method is that it tackles deterministic errors, such as constant bias errors on measurements, which cannot be averaged out by simple averaging.
• An inventive step of the present disclosure is to apply ping-pong retransmissions and to estimate the delay and/or path length for a gNB-UE link based on the length of the combined path over multiple retransmissions.
• Relevant are the specific means for implementing the present invention in a mobile radio system, so that the best possible estimation quality may be achieved.
• the method allows an accurate path-length estimation having a relatively lower measurement resolution (Dt) with UEs and gNBs of limited capabilities to be made.
• Dt measurement resolution
• N ping-pong transmissions the estimation accuracy can ideally be improved to a value of Dt/2N, that is, the measurement resolution would be improved (reduced) by a factor of 2N.
• Dt 32 ns
• the position accuracy would improve from ⁇ 5 m to about ⁇ 0.25 m.
• Figure 5 is an extension of Figure 4 and includes the main effects of the radio channel on the Tx- and Rx- signals and the main effects of the UE processing: ⁇
• the UE will typically not be an ideal reflector, but will have to do an active retransmission of the Rx-signal together with some baseband processing. This baseband processing will add some delay and may add some jitter in case the internal UE clock has some time-varying frequency offsets.
• a first approach is to maximize the bandwidth so that the SI functions become as narrow as possible, that is, more like Dirac pulses.
• massive multiple-input multiple-output (MIMO) beamforming may be used to suppress a large part of the multi-path components, with the exception of the strongest one, by appropriately chosen beamformers. This assumes that the reflected multi-path components have typical angles of arrival (AoA), and that only the strongest multi-path component is received with high power at the center of the narrow beamformer.
• MIMO multiple-input multiple-output
• CIR profiling permits multi-path component parameters, like delay, amplitude and phase, to be identified with high accuracy. Even for a relatively limited RF bandwidth of 20 MHz, for example, for a real-world outdoor non-line-of-sight (NLOS) channel, the multi-path component delays could be estimated with an accuracy of about 0.1 ns or, equivalently, 100 ps. See the finer SI curves 506, 508 in Figure 5.
• the multi-path component delay parameters are estimated from the received channel impulse response to identify the strongest or the intended multi-path component, which should be used for the delay measurement, and to generate a new artificial Tx signal, which contains only the relevant multi-path component.
• This can be achieved by a super-resolution technique, in which the multi-path component parameters are estimated for each multi-path component. Then, all multi-path components, with the exception of the strongest one, are subtracted from the combined channel impulse response. In that way, only the strongest multi-path component is maintained.
• the benefit of this proposal is that, despite a potentially rich scattering environment, each back-and-forth transmission always uses a clean Tx signal containing only the multi-path component of interest. Otherwise, the received multi-path components of the first transmission will be retransmitted from the UE over the rich scattering radio channel, so that the gNB will receive a channel impulse response with an exponentially increasing number of superposed multi-path components per retransmission.
• the received channel impulse response is estimated, and a rising slope of the received channel impulse response above a threshold is identified, for example, to identify and differentiate the transmitted signal first autocorrelation value above the noise.
• the time value above the threshold represents the shortest path of the propagation environment and is used for delay measurement and to generate a new artificial Tx signal (with reference to the preceding paragraph).
• a simple thresholding for doing the delay estimation may be used instead of a more complex ‘profiling’ operation.
• the now quite simple estimated delay is used to generate an artificial
• Tx-signal with one MPC using the estimated delay value Note that such a simplified operation might work quite well in case there is only one strong MPC for all gNB-UE links.
• the UEs may identify the peak of the profiled channel impulse response, which is close to the intended strongest multi-path component, as can be concluded from
• the UE stores the profiled CIR for each reflection process and reports the profiled CIR to the gNB, either directly or at the end of the entire ping-pong process. This enables the gNB to carry out the complex processing for the parameter estimation based on the profiled CIR offline after the ping-pong process has been completed.
• the gNB can apply relevant delay corrections for all of the active UE reflections, as well as for all of the gNB reflections.
• Many positioning use cases have only moderate latency requirements, so that there will be some time available for the corresponding offline processing for doing the profiling for multiple reflections.
• the overall baseband processing for the active reflection has to be considered conventionally. For example, for a 20-MHz bandwidth, the UE will use a 33-ns sample-time grid, which is too coarse by far for present purposes. Therefore, it is proposed to calculate the artificial CIR with the estimated delay, for example, in the frequency domain by adding the appropriate phase slope representing the estimated delay of the MPC relative to the coarse tap delays.
• the UE receives the transmit signals 602, 604 from gNBl and gNB2 simultaneously (two Diracs in ideal illustration) and retransmits (broadcasts) these simultaneously received Dirac signals 602, 604 after a certain baseband processing delay (not shown) back to gNBl and gNB2.
• the main issue for the “mirror” operation is then that the UE does not try to estimate the delays of the Diracs and to retransmit after a certain time (identified by a UE clock timer) the estimated delay values for both Diracs to the gNBs as it is done in prior art. Instead, the UE more or less retransmits as accurately as possible what has been received.
• gNBl has to delete the Dirac from gNB2 and vice versa as otherwise after multiple reflections the number of Diracs will increase exponentially making a proper evaluation challenging.
• Figures 7 and 8 illustrate some aspects of a mirror operation in greater detail.
• a Dirac pulse 701 is transmitted at gNB 1 with a certain delay ti
• a Dirac pulse 702 is transmitted at gNB 2 with delay ti + At x , where At x is an artificial extra delay to ensure good separability of the channel impulse responses of gNBl and gNB2.
• the UE simultaneously receives the Dirac pulses 701, 702 from gNB 1 and 2.
• the UE retransmits the combined CIR including the Dirac pulses 701, 702 received from gNBl and gNB2 at the next possible scheduling opportunity.
• This retransmission of the combined CIR may be seen as an active mirror operation as the relative delays between gNBl and gNB2 are maintained in the combined channel impulse response.
• gNB 1 and gNB2 receive the retransmitted combined channel impulse response with an extra delay T1 (for gNBl) and T2 (for gNB2), so that, for gNBl, Dirac pulse 701 has an extra delay of Dti.
• Dirac pulse 702 is also received, but is deleted from the channel impulse response, as indicated by the overlying “X”, so that it will not be retransmitted in a subsequent step.
• the deletion of Dirac pulse 702 at gNBl was the reason to add the artificial delay At x , so that it would be separated from Dirac pulse 701.
• Figure 8 mainly illustrates the same operation as that of Figure 7, but with a focus on how the delays add up and how the time alignment procedure affects the result.
• the above cancellation of the received part of the channel impulse response is executed at the Location Management Function (LMF), which is placed at the core network.
• LMF Location Management Function
• the LMF obtains a replica of the received channel impulse responses corresponding to the multiple gNBs (two in the example of Figure 7).
• the LMF can filter only the relevant channel impulse response in each case, thereby obtaining multiple independent responses - in the example of Figure 7, two independent responses, one per gNB - from which only the relevant information per gNB is extracted.
• This embodiment corresponds to an implementation example aligned with the conventional positioning architecture where the estimation of the position of the UE is carried out at the LMF at the core network.
• the above cancellation of the received part of the channel impulse is executed at the RAN.
• the gNBs aiming at canceling the non-relevant channel impulse response coordinate among themselves.
• the gNBs communicate via the Xn interface such that a replica of the channel impulse response per gNB is available at the other participating gNB.
• the estimation of the location of the UE then takes place at the respective RAN network element responsible for positioning activities, known as the “local” LMF placed at the RAN.
• This embodiment represents an alternative implementation example to the previous one, involving the alternative positioning architecture where the location management functionality is executed at the RAN, targeting low latency positioning applications.
• Figure 9 provides a simplified message-sequence chart for some possible embodiments for the proposed novel ping-pong positioning methods, and highlights a number of novel implementation and reporting steps. For a proper interaction of the gNBs and the UE, these steps have to be standardized and controlled by corresponding downlink control information (DCI) messages adapted to the method used.
• DCI downlink control information
• messages made between UE 902 and gNBl 904 and gNB2 906 in accordance with various embodiments of the present invention are illustrated.
• gNBl 904 transmits to UE 902 a CSI RS signal #1 or a specific PRS signal #1.
• gNB2 906 transmits to UE 902 a CSI RS signal #2 or a specific PRS signal #2.
• the UE 902 may perform combined base band (BB) processing, as indicated in block 912, to identify the delay of the strongest multi-path component for messages 908, 910 from gNBl 904 and gNB2 906; to remove the weaker multi-path components of those messages; and to retransmit the strongest multi-path components of the messages 908, 910 from gNBl 904 and gNB2906 with a fixed delay relative to the delay of the strongest multi-path component received.
• UE 902 transmits (multicasts) a combined channel impulse response to gNBl 904 and gNB2 906 in messages 914, 916, respectively.
• BB base band
• gNBl 904 removes weak multi-path components and multi-path components of gNB2 906 from message 914 in block 918. Similarly, gNB2 906 removes weak multi-path components and multi-path components of gNBl 904 from message 916 in block 920.
• gNBl 904 transmits a clean channel impulse response to UE 902
• gNB2 906 transmits a clean channel impulse response to UE 902.
• message 926 UE 902 reports to gNBl 904 a profiled channel impulse response.
• N is a number, such as ten (10).
• gNBl 904 may estimate a combined delay over all retransmissions; may estimate a base-band processing delay for UE 902; may use profiling for fine tuning the estimated delay; and/or may divide the delay by N to obtain single path delay estimates, as indicated in block 928.
• Figure 10 is a flow chart illustrating a method performed in accordance with one aspect of the present disclosure.
• reference signals are received from at least one network node.
• at least one parameter relating to a measured channel impulse response is sent back to the at least one network node.
• Channel impulse response is quite general; the response may also be “channel transfer function” or some other CSI-related function.
• the receiving of reference signals and the sending of the at least one parameter relating to the measured channel impulse response is repeated M times for calculation of M single-trip intervals or N round-trip intervals, M and N being integers.
• the parameter relating to a measured channel impulse response to the reference signals may be, for example, the amplitude, phase, delay, or AoA (angle of arrival) of the measured channel impulse response.
• the sending and receiving may occur between two UEs, either using SideLink or without using SideLink. This may also apply to V2V (vehicle-to-vehicle). This is potentially independent timing without explicit control from a gNB.
• V2V vehicle-to-vehicle
• Figure 11 is a flow chart illustrating a method performed in accordance with another aspect of the present disclosure.
• reference signals are transmitted to a network entity B from a network entity A, wherein network entity A and network entity B are each one of a network node and a user equipment.
• a measured channel impulse response is received back from the network entity B after a first round-trip time interval.
• the channel impulse response is sent back to the network entity B.
• the channel impulse response is received back from the network entity B after a second round-trip time interval.
• the preceding sending and receiving is repeated to record N round-trip time intervals, N being an integer.
• a total time for the N round-trip intervals is calculated. And, in block 1114, the total time is divided by N to obtain an estimate of a single round-trip time more accurate by a factor of 2N.
• the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
• 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.
• 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.
• SINR Signal to Interference and Noise Ratio Tx Transmitter UE User Equipment V2V Vehicle-to-Vehicle 3 GPP 3 rd Generation Partnership Project 5G 5 th Generation

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• 2019
  • 2019-10-31 EP EP19809245.4A patent/EP4052516A1/de active Pending
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