Report-free determination of time of flight and round trip time

Abstract

Embodiments of the present invention provide a transceiver configured to receive a first reference signal to transmit a second reference signal. The first reference signal is received by the transceiver at a second point in time, wherein the same reference signal is transmitted by another transceiver at a first point in time. A transceiver, also referred to as a responder, transmits a second reference signal (e.g., as a response to the first reference signal) where a first sample of the second reference signal is transmitted at a third point in time but modified by a cyclic shift defined by a cyclic shift value. The cyclic shift value is derived from a second point in time (measured time of arrival (ToA)) of the received first reference signal and time information associated with a fifth point in time.

Description

Technical Field

[0001] Embodiments of the present invention relate to a transceiver and a user equipment including the transceiver. Another embodiment relates to a system including a user equipment having a transceiver and another user equipment or a base station. Another embodiment relates to a method for exchanging reference signals and a corresponding computer program. Generally, embodiments of the present invention belong to the technical field of positioning of communication devices. Background Art

[0002] FIG. 1 is a schematic representation of an example of a terrestrial wireless network 100. As shown in FIG. 1(a), the network includes a core network 102 and one or more radio access networks RAN1, RAN2, … RAN N . FIG. 1(b) is a schematic representation of an example of a radio access network RAN n which may include one or more base stations gNB1 to gNB5, each base station serving a specific area around the base station schematically represented by the corresponding cells 1061 to 1065. Base stations are provided to serve users within the cells. One or more base stations may serve users in licensed and / or unlicensed frequency bands. The term base station (BS) refers to a gNB in a 5G network, an eNB in UMTS / LTE / LEA / LEA-Pro, or just a BS in other mobile communication standards. A user may be a fixed device or a mobile device. The wireless communication system may also be accessed by mobile or fixed IoT devices connected to the base station or the user. Mobile or fixed devices may include physical devices, ground vehicles (such as robots or cars), aerial vehicles (such as manned or unmanned aerial vehicles (UAVs), the latter also referred to as drones), buildings, and other items or devices in which electronics, software, sensors, actuators, etc. are embedded, and network connections enabling these devices to collect and exchange data over the existing network infrastructure. FIG. 1(b) shows an exemplary view of five cells. However, RAN n may include more or fewer such cells, and RAN nIt may also include only one base station. Fig. 1(b) shows two users, UE1 and UE2, also referred to as user devices or user equipment, which are located in cell 1062 and are served by base station gNB2. Another user UE3 is shown in cell 1064 served by base station gNB4. Arrows 1081, 1082, and 1083 schematically represent uplink / downlink connections for sending data from users UE1, UE2, and UE3 to base stations gNB2, gNB4, or for sending data from base stations gNB2, gNB4 to users UE1, UE2, UE3. This can be achieved on licensed or unlicensed frequency bands. In addition, Fig. 1(b) shows two other devices 1101 and 1102 in cell 1064, such as IoT devices, which can be fixed or mobile devices. Device 1101 accesses the wireless communication system via base station gNB4 to receive and send data, as schematically represented by arrow 1121. Device 1102 accesses the wireless communication system via user UE3, as schematically represented by arrow 1122. The corresponding base stations gNB1 to gNB5 can be connected to the core network 102 via, for example, the S1 interface, via the corresponding backhaul links 1141 to 1145, which are schematically represented by arrows pointing to "core" in Fig. 1(b). The core network 102 can be connected to one or more external networks. The external network can be the Internet, or a private network, such as an intranet or any other type of campus network, such as a private WiFi communication system or a 4G or 5G mobile communication system. In addition, some or all of the corresponding base stations gNB1 to gNB5 can be connected to each other via, for example, the S1 or X2 interface or XN interface in NR via the corresponding backhaul links 1161 to 1165, which are schematically represented by arrows pointing to "gNB" in Fig. 1(b). The sidelink channel allows direct communication between UEs, also known as device-to-device (D2D) communication. The sidelink interface in 3GPP is named PC5.

[0003] For data transmission, a physical resource grid can be used. The physical resource grid can include a set of resource elements to which various physical channels and physical signals are mapped. For example, physical channels can include physical downlink, uplink, and sidelink shared channels (PDSCH, PUSCH, PSSCH) that carry user-specific data, also known as downlink, uplink, sidelink payload data, physical broadcast channel (PBCH) and physical sidelink broadcast channel (PSBCH) that carry, for example, master information block (MIB) and one or more system information blocks (SIB), one or more sidelink information blocks (SLIB) (if supported), physical downlink, uplink, and sidelink control channels (PDCCH, PUCCH, PSSCH) that carry, for example, downlink control information (DCI), uplink control information (UCI), and sidelink control information (SCI), and physical sidelink feedback channel (PSFCH) that carries PC5 feedback response. The sidelink interface can support a two-level SCI, where the two-level SCI refers to a first control region that contains some parts of the SCI, also known as the first-level SCI, and optionally, a second control region that contains a second part of the control information, also known as the second-level SCI.

[0004] For the uplink, the physical channels can further include a physical random access channel (PRACH or RACH), which is used by the UE to access the network once the UE is synchronized and has obtained the MIB and SIB. Physical signals can include reference signals or symbols (RS), synchronization signals, etc. The resource grid can include a frame or radio frame that has a certain duration in the time domain and a given bandwidth in the frequency domain. The frame can have a certain number of subframes with a predetermined length (e.g., 1 ms). Each subframe can include one or more time slots of 12 or 14 OFDM symbols depending on the length of the cyclic prefix CP. The frame can also have a smaller number of OFDM symbols, for example, when using a shortened transmission time interval (sTTI) or a mini-slot / non-slot-based frame structure that includes only a few OFDM symbols.

[0005] A wireless communication system can be any single-tone or multi-carrier system that uses frequency-division multiplexing, such as an orthogonal frequency-division multiplexing (OFDM) system, an orthogonal frequency-division multiple access (OFDMA) system, or any other Inverse Fast Fourier Transform (IFFT)-based signal with or without a Cyclic Prefix (CP), such as Discrete Fourier Transform-spread-OFDM (DFT-s-OFDM). Other waveforms can be used, such as non-orthogonal waveforms for multiple access, such as filter-bank multicarrier (FBMC), generalized frequency division multiplexing (GFDM), or universal filtered multi-carrier (UFMC). The wireless communication system can operate, for example, according to the LTE-Advanced pro standard, or the 5G or New Radio (NR) standard, or the New Radio Unlicensed (NR-U) standard.

[0006] The wireless network or communication system depicted in FIG. 1 can be a heterogeneous network with different coverage networks. For example, a macrocell network, where each macrocell includes a macro base station, such as base stations gNB1 to gNB5, and a small cell base station network, not shown in FIG. 1, such as femto or pico base stations. In addition to the above-ground wireless networks, there are also non-terrestrial wireless communication networks (NTN), including spaceborne transceivers such as satellites and / or airborne transceivers such as unmanned aerial vehicle systems. The non-terrestrial wireless communication network or system can operate in a manner similar to the ground system described above with reference to FIG. 1, for example, according to the LTE-Advanced Pro standard or the 5G or New Radio (NR) standard.

[0007] In a mobile communication network, such as the network described above with reference to FIG. 1, such as an LTE or 5G / NR network, there may be UEs that communicate directly with each other through one or more sidelink (SL) channels, for example, using the PC5 / PC3 interface or Wi-Fi Direct. UEs that communicate directly with each other through the sidelink may include vehicles that communicate directly with other vehicles (V2V communication), and vehicles that communicate with other entities of the wireless communication network, such as roadside units (RSUs), roadside entities (such as traffic lights, traffic signs, or pedestrians) (V2X communication). Depending on the specific network configuration, an RSU may have the functions of a BS or a UE. Other UEs may not be vehicle-related UEs and may include any of the above devices. Such devices may also communicate directly with each other using the SL channel, that is, D2D communication.

[0008] When considering two UEs communicating directly with each other through the sidelink, the two UEs may be served by the same base station, such that the base station may provide sidelink resource allocation configuration or assistance for the UEs. For example, both UEs may be within the coverage area of the base station, such as one of the base stations depicted in FIG. 1. This is referred to as the "in-coverage" scenario. Another scenario is referred to as the "out-of-coverage" scenario. It should be noted that "out-of-coverage" does not mean that these two UEs are not within one of the cells depicted in FIG. 1, but rather means that these UEs

[0009] - may not be connected to the base station. For example, they are not in the RRC connected state, so the UEs do not receive any sidelink resource allocation configuration or assistance from the base station, and / or

[0010] - may be connected to the base station, but for one or more reasons, the base station may not provide sidelink resource allocation configuration or assistance for the UEs, and / or

[0011] - may be connected to a base station that may not support NR V2X services, such as a GSM, UMTS, or LTE base station.

[0012] When considering two UEs communicating directly with each other through the sidelink, for example, using the PC5 / PC3 interface, one of the UEs may also be connected to the BS and may relay information from the BS to the other UE through the sidelink interface and vice versa. The relaying may be performed in the same frequency band (in-band relaying), or another frequency band may be used (out-of-band relaying). In the first case, different time slots can be used to decouple the communication on the Uu and the sidelink, similar to a time division duplex (TDD) system.

[0013] Figure 2 is a schematic representation of a scenario within the coverage area, where two UEs communicating directly with each other are both connected to the base station. The coverage area of the base station gNB is schematically represented by the circle 200, which substantially corresponds to the cell schematically shown in FIG. 1. The UEs communicating directly with each other include a first vehicle 202 and a second vehicle 204, both of which are within the coverage area 200 of the base station gNB. Both vehicles 202, 204 are connected to the base station gNB, and, in addition, they are directly connected to each other via the PC5 interface. The gNB assists in the scheduling and / or interference management of V2V services via control signaling on the Uu interface, which is the radio interface between the base station and the UE. In other words, the gNB provides SL resource allocation configuration or assistance to the UE, and the gNB allocates resources for V2V communication via the sidelink. This configuration is also referred to as Mode 1 configuration in NR V2X and Mode 3 configuration in LTE V2X.

[0014] Figure 3 is a schematic representation of a scenario outside the coverage area, where the UEs communicating directly with each other are either not connected to the base station, although they may physically be within the cell of the wireless communication network, or some or all of the UEs communicating directly with each other are connected to the base station but the base station does not provide SL resource allocation configuration or assistance. Three vehicles 206, 208, and 210 are shown communicating directly with each other via the sidelink, for example using the PC5 interface. The scheduling and / or interference management of V2V services is based on an algorithm implemented between the vehicles. This configuration is also referred to as Mode 2 configuration in NR V2X and Mode 4 configuration in LTE V2X. As described above, Figure 3 the scenario in Figure 2a is a scenario outside the coverage area, which does not necessarily mean that the corresponding Mode 2 UEs in NR or Mode 4 UEs in LTE are outside the coverage area 200 of the base station, but rather means that the corresponding Mode 2 UEs in NR and Mode 4 UEs in LTE are not served by the base station, not connected to the base station in the coverage area, or connected to the base station but do not receive SL resource allocation configuration or assistance from the base station. Thus, it may be the case that within the Figure 2b coverage area 200 shown in

[0015] In addition to the NR Mode 1 or LTE Mode 3 UEs 202, 204, there are also NR Mode 2 or LTE Mode 4 UEs 206, 208, 210. In addition, Figure 2a and Figure 2bA vehicle UE is shown, but it is noted that the described in - coverage and out - of - coverage scenarios also apply to non - vehicle UEs. In other words, any UE that uses the SL channel to communicate directly with another UE, such as a handheld device, can be in - coverage and out - of - coverage.

[0016] Within the above - mentioned communication network, the accuracy can be determined or estimated by determining the so - called round - trip time (RTT). When performing an RTT measurement, a signal or a reference signal is exchanged between one device (e.g., a UE) and another device (such as another UE or a base station). RTT measurements are well - supported by 3GPP standards. The current process requires that the first UE can report to the network or another device, or if the ranging is calculated by the UE itself, the UE can receive a measurement report, e.g., from the network or from another UE (in the case of sidelink). Therefore, an improved method is needed. Summary of the Invention

[0017] The object of the present invention is to improve position determination, especially in terms of reporting requirements.

[0018] The subject matter of the independent claims solves this problem.

[0019] An embodiment of the present invention provides a transceiver configured to receive a first reference signal to transmit a second reference signal. The first reference signal is received by the transceiver at a second time point, where the same reference signal is transmitted by another transceiver at a first time point. The transceiver, also referred to as a responder, is set to transmit (send) the second reference signal (e.g., as a response to the first reference signal), where the transmission time of the second reference signal (represented by the start of an OFDM symbol (e.g., the first sample) or another reference point of the OFDM symbol such as the start of the primary symbol, etc.) is regarded as a third time point. However, the second reference signal is modified by a cyclic shift defined by a cyclic shift value. The cyclic shift value is derived from the second time point (measured time of arrival (ToA)) of the received first reference signal and time information associated with a fifth time point.

[0020] Another embodiment provides a user equipment including a transceiver. Here, another transceiver can be part of a base station or part of another user equipment (sidelink).

[0021] Another embodiment relates to a system including a user equipment and another user equipment or a base station.

[0022] Another embodiment provides a method for exchanging reference signals. The method includes the following steps:

[0023] - Receive a first reference signal and a second time point, where the first reference signal is sent by another transceiver at a first time point; and

[0024] - Transmit a second reference signal, where a first sample of the second reference signal is set to be transmitted or sent at a third time point, and the second reference signal is modified by a cyclic shift defined by a cyclic shift value. As described above, attention is drawn to the cyclic shift value.

[0025] According to an embodiment, the method may be computer-implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the present invention will subsequently be discussed with reference to the accompanying drawings, where:

[0027] Figure 1a and 1b shows a schematic representation of a terrestrial wireless network in different configurations to discuss the background of the embodiments;

[0028] Figure 2a shows a schematic representation of a scenario within the coverage area;

[0029] Figure 2b shows a schematic representation of a scenario outside the coverage area;

[0030] Figure 3 shows a schematic diagram illustrating the timing of the RTT signal;

[0031] Figure 4 shows a schematic diagram illustrating the RTT using cyclic shift according to an embodiment;

[0032] Figure 5a schematically illustrates an example of the structure (without cyclic shift) and correlation of an OFDM symbol to illustrate the embodiments;

[0033] Figure 5b schematically illustrates a cyclic-shifted OFDM symbol according to an embodiment and its resulting effects;

[0034] Figure 5c schematically illustrates a possible implementation of cyclic correlation. In this example, an implementation in the time domain is illustrated.

[0035] Figure 6 shows a schematic block diagram illustrating a method for position determination according to an embodiment;

[0036] Figure 7a shows a schematic application scenario with a roadside unit (RSU) according to an embodiment;

[0037] Figure 7b shows an illustration according to Figure 7aSchematic diagram of correlator outputs of three RSUs of an embodiment;

[0038] Figure 8 Schematically illustrates a method for location determination in a communication network with devices (here RSU, LMF, and gNB entities) according to an embodiment;

[0039] Figure 9 Schematically shows a configuration according to an embodiment, where one initiating UE communicates with one or more responding UEs;

[0040] Figure 10 Schematically shows a block diagram of different UEs for discussing the location determination principle according to an embodiment;

[0041] Figure 11a Schematically shows a flowchart of a process involving the LMF;

[0042] Figure 11b Schematically shows a flowchart of a process of a target UE according to an embodiment;

[0043] Figure 12 Schematically shows the principle of location calculation using sidelink and calculating the location by the UE;

[0044] Figure 13 Shows a schematic block diagram of a hardware implementation. Detailed implementation mode

[0045] Hereinafter, embodiments of the present invention will be discussed with reference to the accompanying drawings, where the same reference numerals are provided to objects having the same or similar functions, so that their descriptions are mutually applicable and interchangeable.

[0046] Before discussing the embodiments of the present invention, the principle of RTT measurement (round-trip time) will be discussed. The process for determining RTT can be characterized as follows: Here reference is made to Figure 3 .

[0047] In Figure 3 the lower row, the receiving and transmitting processes of the transceiver 12 (e.g., of the UE) will be discussed. The steps of receiving and transmitting are called downlink symbol @ UE (see RS1) and uplink symbol @ UE (see RS2). The communication established with another entity 12, here is Figure 3 the transmission point shown in the top row. The transmitting process and the receiving process are called DL symbol @ TRP and UL symbol @ TRP.

[0048] The steps performed by these two entities are as described below:

[0049] 1. The network (or in the case of sidelink, the UE) defines reference signals (RS1, RS2) useful for ToA (Time of Arrival) measurement and transmits the signals in the DL (or forward link). For simplicity, we only consider gNB / UE operations hereinafter. However, this concept is also fully applicable to sidelink.

[0050] 2. The network reports the RS configuration to UE 12.

[0051] 3. The network configures RS2 (usually SRS) for UL transmission. This configuration includes the time slots for UL signals, one or more positions in the time slots, OFDM symbol parameters, and RS sequence parameters.

[0052] 4. In addition, the network adjusts the timing advance (TA) and configures the power control for UL.

[0053] 5. The TA setting and RS signal configuration define the ToT (Time of Transmission) of the RS.

[0054] 6. For RTT measurement, the UE reports the time difference (t3 - t2) between the ToA and ToT with high time resolution.

[0055] 7. For reporting, the network must establish a communication link for the exchange of reports.

[0056] 8. The network measures the DL ToT of RS1 ( Figure 3 or Figure 4 t1 in

[0057] 9. From the 4 time values t1…t4, the ToF (Time of Flight) can be calculated by the following formula

[0058] ToF = ((t4 - t1) – (t3 - t2)) / 2

[0059] 10. The distance can be calculated from the ToF.

[0060] As described above or Figure 3 shown, the process usually uses (or requires) that the UE can report to the network (TRP 10), or if the ranging is calculated by the UE 12 itself, the UE 12 can receive the measurement port from the network or in the case of sidelink, from another UE.

[0061] For positioning, the following issues may be relevant: The report needs to be able to decode the signal without errors. This may require a higher UE TX power (to ensure that the signal arrives with sufficient SINR). The report may introduce additional latency. Triangulation-based positioning must establish several links. For positioning, even if the RS is received with a very low SINR due to the correlation gain corresponding to the sequence length, the RS can be processed. This allows:

[0062] ο Use a distant gNB (or UE) for measurements, even if the path loss is high and the UE cannot receive or send a report to this network entity.

[0063] ο Alternatively, the UE can transmit the signal only at a lower power to minimize interference to other devices (such as the gNB close to the UE). Only in the configuration phase, the UE (or another network entity) can use the transmission power sufficient to send the configuration information.

[0064] In the current process, it is assumed that reporting is possible (directly or indirectly) and latency is not critical.

[0065] In the context of the positioning reference signal design, we have shown that for positioning, it is sufficient to receive a reference signal with a very low SINR (e.g., -20 dB). This low SINR operation does not support communication. Therefore, the report must be established by other links (e.g., report to the nearest gNB or UE and exchange information between gNBs). Each UE sends or receives measurements from its "serving gNB", which is usually the gNB closest to the UE. Or configure a higher signal power for reporting, which may cause more interference or even overload to nearby gNBs.

[0066] The 5G network supports "multiple access" for each OFDM symbol. An OFDM symbol includes several resource elements (REs). Several UEs can use the same OFDM symbol for transmission, but can use different REs. Each RE can be mapped to a subcarrier of the OFDM symbol. To maintain orthogonality between subcarriers, the signals of different UEs must arrive at the receiver with a limited time offset. The allowed uncertainty depends on the cyclic prefix length. To ensure that the signals of different UEs arrive within this uncertainty, the network configures a time offset ("timing advance" = TA) relative to the symbol timing recovered from the downlink signal. For arrival time measurement, a correlator can be used. The input of the correlator can be the data received within a time interval ("window") and the reference signal. The correlator usually measures the time relative to the "window start". For a cyclic correlator, the window length is the same as the FFT length (= OFDM symbol without CP). The principle of the cyclic correlator is as Figure 5cAs depicted. If performed in the time domain, two copies of the signal with the main symbol length (equivalent to the FFT length) in the window can be combined into a vector of double length, and the cross-correlation with the reference signal can be performed. For other correlators, the window length may be different, but in this case, the subcarriers are no longer orthogonal, and ICI (Inter-Carrier Interference) may degrade the performance.

[0067] The window start can be selected according to the tolerance of the non-ideal TA setting and the expected "channel excess delay" (=delay of the latest (relevant) multipath component). For ideal TA, the optimal window position is the "end of the CP (Cyclic Prefix)". This minimizes ISI (Inter-Symbol Interference). But other positions are also possible. In Figure 5c the window covers a part of the CP and ignores a part at the end of the main symbol. The effective ToA and ToT ((Transmission Time) are usually the time offset of the OFDM symbol relative to the "OFDM window" plus the timestamp of the window start. For ideal symbol timing recovery and ideal TA setting, the uplink signal arrives in frame synchronization with the network, and the measured delay relative to the window start can be zero. For TDD, ideal symbol time recovery and ideal TA setting mean assuming that the TX and RX framing of the gNB are aligned (for FDD, the offset is not critical, but the framing can still be aligned, or at least the signals received from several UEs are aligned). The OFDM symbol framing of the UE is delayed by ToF (Time of Flight) relative to the gNB OFDM symbol framing. The TX framing of the UE is set relative to the recovered RX framing. To ensure that the UL signal arrives aligned with the gNB DL / UL framing, the nominal value (ideal value) of the TA is 2*ToF. The TA is configured by the gNB. Ideal symbol time recovery and ideal TA setting are considered infeasible (if feasible, the TA value would already be the same as the RTT, at least for TDD (for FDD, the gNB offset between TX and RX framing must be considered). The RTT process takes into account the non-ideal TA setting or non-ideal OFDM symbol timing recovery of the UE.

[0068] Starting from this process, the RTT process can be described as follows: The gNB calculates the difference between t4 (Time of Arrival (ToA) of the UL signal) and t1 (Transmission Time (ToT) of the DL signal). The UE measures (or Set ) the difference between t3 (Transmission Time (ToT) of the UL signal) and t2 (ToA of the DL signal). "Measuring" means: measuring the difference between ToA,DL and ToT,UL with a resolution better than the sampling interval (TS). "Setting" means: measuring ToA,DL with a resolution better than TS. The difference can be quantized (e.g., quantized to T S value, where T Sis the sampling time interval according to the nominal sampling frequency). The resulting ToT, UL may no longer be aligned with the sampling grid and may require "resampling" of the uplink PRS. If (t3 - t2) is set, the TA must be considered. From these two values, the ToF (time of flight = distance / flight speed) can be calculated

[0069] ToF = ((t4 - t1) – (t3 - t2)) / 2

[0070] This principle also applies to non-ideal TA settings. The ToA (t 4,rel which is measured relative to the gNB framing (t4) can also be an indicator of non-ideal TA settings and the required TA adjustment. To ensure that the arrival of the UL signal is consistent with the gNB framing, an "ideal" TA setting (in this case, the measurement would be t 4,rel = 0), resulting in

[0071] t3 - t2 = k * t Sym – 2 * ToF

[0072] where k takes into account that the signal is sent in another time slot or OFDM symbol. Non-ideal TA settings result in t 4,rel being different from 0.

[0073] Starting from this process, the exchange of reference signals (the first reference signal sent from outside the UE and the second transmission signal sent from the UE to the outside) is improved according to the concepts of the embodiments. These improvements mainly focus on improvements in reporting or reporting requirements.

[0074] Embodiments of the present invention provide a transceiver, such as a transceiver UE, which exchanges reference signals externally (e.g., with a base station or another UE). In Figure 4 the schematic diagram, the steps performed by the UE 12 including the transceiver are shown in the lower row, where the external entity 10 and the corresponding steps are shown in the top row. The external entity 10 is referred to as a TRP (transmission point), where those skilled in the art interpret this term as a synonym for a UE ( / another UE) including a transceiver or a base station including a transceiver.

[0075] The UE 10 is configured to receive and send signals, in particular the reference signals RS1 and RS2. Here, the first reference signal RS1 is referred to as a DL symbol (downlink symbol), where the second reference signal RS2 is referred to as a UL symbol (uplink symbol).

[0076] UE 12 is configured to receive a first reference signal, also known as a DL symbol, at a second time point t2. This first reference signal RS1 / DL symbol is transmitted by transceiver 10 at a first time point t1. This means that the transceiver is configured to determine the second time point / arrival time. This can be done by measurements to determine the second time point.

[0077] In response to the reception of the first reference signal RS1 / DL symbol, transceiver 12 transmits a second reference signal RS2, also known as a UL symbol. The transmission is performed or starts at a third time point t3, but with a modified symbol. Specifically, the content of the original first sample (0123456) of the second reference signal RS2 is transmitted at a fifth time point, where the end of the sample is added to the beginning of the transmitted main symbol, and the cyclic prefix (CP) can now include different data. The modified symbol is transmitted at t3.

[0078] The modification of the RS2 content is done as follows: The second reference signal is modified by a so-called cyclic shift such that the transmission of the OFDM symbol 012345 can be postponed to the fifth time point, so that the correlation with this symbol order will determine the relevant peak of the postponement / delay / shift relative to t3. (See Figure 5c ). Thus, the fifth time point t5 may be later than the third time point t3. The cyclic shift CS is defined by a so-called cyclic shift value t cs defined.

[0079] According to an embodiment, the cyclic shift value t cs is derived from the second time point of the received first reference signal and the time information associated with the fifth time point t5. According to an embodiment, the second time point can be measured, for example, using a typical time of arrival (ToA) measurement. For example, the time information associated with the fifth time point may include the desired duration between the second time point and the fifth time point. This value can be set by the network or can be derived from other configuration parameters. For example, the duration of the time interval can be calculated based on the formula t5 = t2 + n * t Sym - TA. Here, TA is the timing advance value, which is usually set by the network or remains constant (semi-persistent) until updated. "n" can be derived from the scheduling of the OFDM symbols configured for the uplink signal relative to the OFDM symbols used for the downlink reference signal. Thus, the formula meets the requirement of deriving the cyclic shift value based on the second time point t2 of the received first reference signal and the time information associated with the fifth time point t5.

[0080] In other words: The third time point t3 can represent the time of the first sample of the modified OFDM symbol, where the modification results in a valid time point defined by the fifth time point t5. According to an embodiment, the transmitter is configured to calculate the fifth time point based on the second time point and a cyclic shift and / or based on the desired duration between the third time point and the second time point, where the third time point is set according to a synchronization requirement (TA setting).

[0081] Then, at the sixth time point t6, the correlation peak of the second reference signal RS2 / UL symbol transmitted by the user equipment 12 can be detected by another transceiver 10. Therefore, the TRP 10 determines t6 as the time of arrival (ToA). Note that this sixth time point is different from the fourth time point t4 representing the ToA, at which, if a signal without a cyclic shift is transmitted, the second signal would be detected (see the time point t4 discussed in the context of Figure 4 In the same way, the fifth time point is different from the third time point representing the time window in which the second signal would be transmitted without a cyclic shift, e.g., it is shifted and postponed relative to the third time point by a cyclic shift.

[0082] Applying a cyclic shift has two main advantages:

[0083] 1. For the example of two UEs (UE1 plus UE2 or TRP plus UE2), a low-power reference signal can be used and RTT measurements can be performed without any reporting because the time difference t5 to t2 can be kept constant. Therefore, according to an embodiment, considering the desired (constant, known, defined) duration between the second time point and the fifth time point, the time of flight and / or round-trip time can be calculated based on the difference between the sixth time point and the first time point.

[0084] 2. For the example of multiple UEs (UE1 plus UE2a, UE2b,... or TRP plus UE2a, UE2b,...),

[0085] different cyclic shifts can be used for different UEs to be able to distinguish them.

[0086] Regarding the reference symbol, it should be noted that the first reference symbol RS1 received at the second time point t2 can include an OFDM symbol with a cyclic prefix as a predetermined time reference point. As described above, the first reference signal can include an initiating signal for initiating position measurement.

[0087] Starting from this point, the following method can be summarized. According to an embodiment, the goal is to make the difference between the effective ToT (Transmission Time) related to positioning / ranging measurements independent of the set of ToTs set according to the network symbol timing requirements, where the effective ToT is considered the time related to the ToA (Time of Arrival) detected by the receiver, and the difference between ToT and ToA represents the Time of Flight (ToF). The following nomenclature is used hereinafter:

[0088] οt1 is the ToT of the DL signal transmitted by the first device

[0089] οt2 is the ToA measured by the second device (e.g., UE)

[0090] οt3 is the time set according to the network symbol timing requirements

[0091] οt4 is the time when the UL signal arrives at the first device.

[0092] οt5 is the effective ToT obtained by modifying the transmitted symbol by cyclic shift

[0093] οt6 is the ToA detected assuming the cyclic correlation of the received signal with the (unshifted) reference signal.

[0094] It should be noted that in the context of this application, examples for sidelink or Uu applications are provided. The proposed method is applicable to any two or more ranging devices, where, unless explicitly mentioned, the first device or one or more second devices can be a UE, TRP, BS, NTN BS, NTN-UE, RSU (Road Side Unit), PRU (Positioning Reference Unit), etc.

[0095] · This means

[0096] οt1, t4, and t6 are measured or set using the clock of the first device (network device or first UE)

[0097] οt2, t3, and t5 are measured or set using the clock of the second device (e.g., UE)

[0098] ο The second device can recover the clock by performing measurements (e.g., detection of synchronization signals) on the signals transmitted by the first device (e.g., gNB)

[0099] · To maintain the timing constraints of the network (or other receiving devices), t3 is set accordingly (e.g., by adjusting the TA)

[0100] · t5 is calculated based on the measured t2 and the desired (t5 - t2) difference.

[0101] · Using cyclic shift, the effective correlation peak shifts, but the TA can still be maintained. This allows t3 and t5 to be different

[0102] οt5 is used for reporting the difference t5 - t2 (instead of t5 - t2)

[0103] οt3 is set according to TA requirements

[0104] · This allows the difference (t5 - t2) to be set to a desired (constant) value.

[0105] · The difference between t3 and t5 is implemented as a cyclic shift.

[0106] t CS = t5 – t3

[0107] · If the difference t5 - t2 can be set to a desired value, the reporting of the difference can be simplified

[0108] ο A constant value is used and is configured, for example, together with the RS configuration.

[0109] ο The desired difference is derived from parameters that are known at both the UE and the gNB (such as OFDM symbol parameter settings).

[0110] For example, the proposed solution is applicable to many different scenarios, where the term responder is used for a device that responds according to t5. According to an embodiment, the network can configure the desired (t5 - t2) difference. For example, the UE derives t3 (= the time of the first sample of the OFDM symbol) from the recovered OFDM symbol timing and calculates the TA setting t5 based on the measured t2 and the desired (t5 - t2) difference. The difference between t3 and t5 is applied as a cyclic shift to the reference signal. For the selection of the desired t5 - t2 difference, different methods can be considered: Select a fixed value independent of TA. Select a value for the difference between t5 and t3 that is covered by the supported CS range. Otherwise, modulo arithmetic can be used as described below and may lead to ambiguity. In the case of the COMB structure, additional ambiguity may result. To avoid ambiguity, the preferred CS range may also depend on the COMB factor. If only one OFDM symbol is used, the CS range in samples is CS samples = FFTlength / COMB_factor, and in time is t CS,max = CS samples / fs. As described above, the nominal difference from the ideal TA is t3 - t2 = k*t Sym - 2*ToF. "k" is known from the scheduling of the signal transmission (= the position where the RS is configured in the frame), and 2*ToF can be replaced with the known TA, resulting in

[0111] t3 = t2 + k*t Sym – TA

[0112] Therefore, the difference t3 - t2 is k*tSym –TA, and is known at the UE and the gNB (assuming the TA is signaled as a value and is not adjusted through a cycle that is adjusted by the "increment / decrement" of the TA until the symbol reaches the desired time). In this case, the TA value can be known only by the UE. Additionally, it is not necessary to derive t3 from t2. t3 can also be derived from other synchronization signals (such as SSB).

[0113] In all cases, the required cyclic shift can be derived from the configured t5 - t2 difference and the calculated t3. t2, t3, and t5 are measured (or set) relative to the UE's clock. The UE's clock can be derived from the network clock and can have a (small) offset according to the limited synchronization accuracy.

[0114] If the UE responds to a gNB different from the serving gNB (adjacent gNB = n - gNB), the n - gNB may not know the TA setting relative to the s - gNB. For transmissions to the n - gNB, the UE can use the same framing as for transmissions to the s - gNB, or can re - adjust the frame according to the TA value applicable to the n - gNB or the default TA setting.

[0115] Regarding the second reference signal UL symbol, it should be noted that this second reference signal UL symbol is received by another transceiver 10, which can perform ToA measurements based on the cyclic (cross) - correlation with the configured (unmodified) transmitted reference signal, resulting in a sixth time point t6. Below, the correlation and other details of the above - mentioned method will be discussed in detail. Note that all details discussed below are optional features according to further embodiments. Figure 5 depicts the principle of arrival - time measurement of an OFDM signal with a cyclic prefix and cyclic correlation. We assume that the transmitted signal is an OFDM symbol with a cyclic prefix (CP). The CP is a copy of the last part of the transmitted signal. One possible implementation of cyclic correlation is:

[0116] ο The cyclic correlation uses the "main part" of the OFDM symbol as input. The OFDM symbol timing of the received signal is recovered, and a "window" is determined according to the FFT length. The samples within the window are used for further processing. In the absence of multipath propagation, the window can start from any position within the CP. In multipath propagation, the window typically starts from the end of the CP.

[0117] ο The samples within the window are transformed to the frequency domain using the FFT.

[0118] ο The receiver knows the transmitted reference signal (RS) or its FFT (the frequency - domain representation of the RS)

[0119] ο In the frequency domain, the received signal is multiplied by the complex conjugate of the transmitted RS. The result is the estimated frequency response of the channel.

[0120] ο The inverse FFT of the frequency response is the "circular correlation" in the time domain.

[0121] ο The circular correlation represents the convolution of the channel impulse response with the sin(x) / x function according to the used bandwidth of the RS.

[0122] ο If the RS has good autocorrelation properties, the position of the correlation peak represents the time of arrival (ToA) relative to the time of the first sample of the window. The ToA can be estimated together with the time of the first sample of the window.

[0123] ο In addition to the ToA of the first arrival path, the ToA of the multipath components can also be estimated.

[0124] Regarding Figure 5a and 5b comparison, it can be seen that the cyclic shift (CS) modifies the OFDM symbol with a cyclic prefix. Figure 5a shows the original OFDM symbol, which has a main symbol MS and a cyclic prefix that is the same as the "B" part of the main symbol. Starting from the cyclic shift (CS) defined by the cyclic shift value t cs , the main symbol MS is shifted, and a new CP is generated after the cyclic shift (CS) of the main symbol MS. The last part of the symbol, here the seventh part, is copied to the beginning and used as the cyclic prefix. The result of the circular correlation is shown in the corresponding second plot of Figure 5 ( Figure 5b ). According to Figure 5a , the circular correlation will determine the correlation peak related to the first arrival path at the position ToA (time of arrival). Starting from the modified OFDM symbol according to an embodiment of the present invention (see Figure 5b ), the output of the circular correlation will deliver different detected ToA', for example, delayed by t cs . Note that the correlation is performed with the unshifted reference signal.

[0125] The circular correlation can also be calculated in the time domain. In this case, two copies of the signal within the window are concatenated and cross-correlated with the reference signal ( Figure 5c ). Alternatively, two copies of the reference signal are concatenated and correlated with the signal received in the time window.

[0126] A cyclic shift can be applied to the RS before transmission. Before CP insertion, a cyclic shift is applied to the main symbol. If the cyclically shifted RS is correlated with the (unshifted) RS, the ToA rel) ToA (see Figure 5b ). The cyclic shift can also be negative. Due to the cyclic behavior of the cyclic correlation, the detected ToArel will be

[0127] ToA rel = ToA rel,Sym + mod(t CS , t Sym )

[0128] where

[0129] ToA rel,Sym is the ToA of the symbol without cyclic shift rel . This part covers the offset recovered from the non-ideal OFDM window

[0130] t CS is the cyclic shift applied to the RS

[0131] t Sym is the length of the main part of the symbol (symbol length without CP)

[0132] mod() is the modulo operation.

[0133] Combined with the timestamp of the first sample of the window, the ToA of the RS can be calculated

[0134] ToA = ToA rel + t WindowStart

[0135] As described above, this results in a situation where the second reference signal transmitted at the third time point and received at the fourth time point causes the ToA of the cyclic correlation to be measured at the sixth time point. In other words, this means that such a reference signal will be received by the receiver or another transceiver, and a ToA measurement is formed based on the cyclic (cross) correlation of the received signal with the configured (or modified) transmitted reference signal, thereby generating the sixth time point, and the difference between the sixth time point and the fifth time point represents the time of flight. Here, the first OFDM main symbol is transmitted at the time point t5 (the fifth time point). Note that the cyclic shift value derived from the second time point t2 is also derived from the time information associated with this fifth time point t5. For example, this time information can be represented by the value t csIt is described as follows. In other words, this means that at the sixth time point, assuming a cyclic relationship, the start of the OFDM symbol ToA’ of the reference signal RS is detected by the receiver or another transceiver, where the sixth time point is different from the fourth time point, and the fourth time point represents the time window at which the start of the OFDM symbol of the second reference signal will be received without cyclic shift. According to an embodiment, the difference between the fourth time point and the sixth time point depends on the applied cyclic shift, where this difference is unknown at the receiver and / or does not require further processing. Note that the difference between the sixth time point and the associated fifth time point represents the time of flight (ToF) between the transmitter and the receiver.

[0136] Refer to the above Figure 4 This relationship will be discussed in detail Figure 4 An example is shown of how to apply a cyclic shift to the RTT measurement to avoid reporting the difference "dt32" between t3 and t2.

[0137] · Assume that the UE is synchronized with the DL signal (the OFDM symbol timing is recovered with acceptable accuracy, and the frequency offsets of UL and DL are within the feasible tolerance), and the network has adjusted the required timing advance (TA). The timing advance adjustment may be suboptimal (e.g., adjusted only based on measurements with limited accuracy) or set to a default value.

[0138] · Based on the recovered OFDM framing, the configured resources (slot number and OFDM symbol index within the slot) and the TA setting, the UE can calculate t3, which represents the transmission time when the signal arrives at the gNB in accordance with the network synchronization requirements.

[0139] · If the UE receives a DL symbol (DL-RS) suitable for high-accuracy ToA measurement (e.g., DL-PRS), the UE can determine t2 by measuring the ToA of the DL-RS.

[0140] · The network can configure the desired difference dt between the effective transmission time (t5) and the estimated ToA (t2) of the DL-RA 52 .

[0141] t5 = t2 + dt 52

[0142] · t5 may be different from t3. A cyclic shift can be applied to the RS transmitted by the UE instead of readjusting t3, which may violate the network symbol timing requirements. This maintains t3. The required cyclic shift is

[0143] t CS = t5 - t3

[0144] · If the calculated t CS is greater than or equal to 0 and less than tSym , the difference between t5 and t3 can be compensated for by cyclic shift only, where t Sym is the duration of the main part of the OFDM symbol. If the calculated t CS exceeds this range, modulo arithmetic can be applied

[0145] t CS = mod(t5 - t3, t Sym )

[0146] In this case, the receiver should consider the ambiguity. Usually, the symbol duration is much larger than the ToF. Therefore, the ambiguity can be easily resolved.

[0147] · t3, t5, and t2 are measured relative to the UE clock. Only the differences between the values are relevant. Therefore, if the UE clock ("time") is offset from the network time, this concept also applies.

[0148] According to an embodiment, the second reference signal is modified by cyclic shift, i.e., in such a way that before the cyclic prefix is inserted, the OFDM symbol is cyclic shifted ( Figure 5a and Figure 5b shows the principle, i.e., the part "89AB" is copied to the beginning and the part "01234567" is moved to the end), where the cyclic prefix is a copy of the end of the OFDM symbol (see Figure 5b the digit 7 of the OFDM symbol in

[0149] According to an embodiment, the cyclic shift can be applied to the RS by different methods

[0150] · Applying the cyclic shift in the time domain (see Figure 5c )

[0151] · Applying the cyclic shift in the frequency domain

[0152] If the cyclic shift is an integer multiple of the sampling period used, the cyclic shift can be achieved by reordering the samples of the vector in the time domain. The calculated required cyclic shift is usually not an integer multiple of the sampling period. Therefore, applying the cyclic shift in the frequency domain may be more efficient. The cyclic shift in the frequency domain can be achieved as follows

[0153] S (n) = R (n) · e jαn

[0154] where

[0155]

[0156] wherein,

[0157] N is the FFT length

[0158] n is the index, n ∈ [0, (N - 1)]

[0159] R (n) is the frequency - domain representation of the RS without cyclic shift. R (n) = fft(r (n) ), where r (n) is the time - domain signal of the RS without CP

[0160] t CS is the target cyclic shift (in seconds)

[0161] T0 is the sampling period, in seconds

[0162] S (n) is the frequency - domain representation of the RS with cyclic shift.

[0163] According to the embodiment, as Figure 4 shown, the cyclic shift performed by the transceiver 12 can be carried out in two different ways, namely depending on whether the cyclic shift is applied in the frequency domain or the time domain.

[0164] In the frequency domain, for example, using FFT, two vectors of the same length are multiplied in the frequency domain. The result is information about the phase, where the edge steepness gives information about the delay between t4 and t6.

[0165] In the time domain, the signal used (here the received reference signal) is repeatedly concatenated ( Figure 5c ), so that by using cross - correlation, the start of the modified OFDM symbol (see reference numeral ToA’) can be easily determined.

[0166] As described above, the modification is performed based on the cyclic shift, where the cyclic shift is defined by a so - called cyclic shift value. This cyclic shift value can be derived from the time information associated with the fifth time point. According to the embodiment, this time information can include the desired duration between the fifth time point and the second time point, that is, this information includes t cs and the duration from t3 to t2. According to the embodiment, the difference between the fifth time point and the third time point directly represents the required cyclic shift value, where the third time point is selected according to the network synchronization requirements and the scheduling of the second reference signal. The synchronization requirements can be defined as relative DL synchronization signals such as SSB, DL - PRS, CSI - RS, and are adjusted by the network by configuring TA or using the default value of TA. It should be noted that according to the embodiment, the cyclic shift value can be set to zero, so that no cyclic shift is performed. When, according to the embodiment, the cyclic shift value is only defined as t cs , the third time point can be derived from the measured second time point

[0167] t3 = t2 + t TX – TA;

[0168] where t TX represents the scheduling of the OFDM symbol for transmitting the second reference signal relative to the scheduling of the first reference signal, and TA is set by the network or remains fixed ("semi-persistent") prior to an update.

[0169] Note that the expected duration between the fifth time point and the second time point is constant or semi-constant (constant for a configurable number of transmissions or duration), or derived from another parameter such as the transmitter ID. According to an embodiment, the designed duration is configured or pre-configured. According to a further embodiment, the (required) cyclic shift value is calculated from the difference between the fifth time point and the third time point

[0170] t CS = t5 - t3

[0171] or if the difference t5 - t3 is less than 0 or greater than or equal to t Sym ,

[0172] t CS = mod(t5 - t3, t Sym )

[0173] where t Sym is the duration of the OFDM symbol without the cyclic prefix.

[0174] According to a further embodiment, the transceiver may be configured with a second cyclic shift value, or the second cyclic offset value is derived from other configuration parameters such as the antenna port, where the second cyclic shift value is added to the first cyclic shift value; and / or where the second cyclic shift value is encoded differently compared to the first cyclic shift value. For example, if different second reference signals are to be sent to different or other transceivers, different cyclic shifts are applied to these signals. Refer to Figure 7aDiscuss its background where multiple transceivers (e.g., roadside units (RSUs)) exchange communication signals / reference signals with another transceiver (such as a vehicle). The vehicle may be the initiator and the RSU may be the responder. Thus, this means that according to an embodiment, several transceivers (responders) can use the same resources in time and frequency, and the desired difference between the fifth time point and the second time point is configured differently. For example, different cyclic shifts are configured for different transceivers among several transceivers, resulting in several correlation peaks that represent the sixth time point of each signal sent to a corresponding one of the several transceivers. Note that the selected configuration values allow the assignment between the correlation peaks and the associated transceivers. According to an embodiment, several transceivers can respond to a first reference signal sent by another transceiver that forms the initiator. The cyclic shift depends on responder-specific information or responder / anchor ID information. Thus, the cyclic shift value can also be derived from the first reference signal.

[0175] According to an embodiment, the UE is configured to receive a configuration message, for example, from the network or another device (in the case of sidelink). Based on this configuration message, the cyclic shift value is set. For example, the configuration includes information for selecting a CS value or a range / interval. The CS value may depend on responder-specific information or responder / anchor ID. The configuration includes information for verifying the required CS value estimated. According to an embodiment, the UE may receive this configuration in a first step, so that it can receive an RS signal from another device in a second step. After that, the configuration message is applied to derive the CS value. Note that this configuration message represents time information associated with a time point. As described above, considering the measured second time point (measured time of arrival) as a reference, the signature value is derived from this configuration message / time information associated with the fifth time point. As described above, this reference signal may also include information that affects the CS value. After that, RS2 is sent together with the selected CS value.

[0176] Note that according to an embodiment, different reference signals can be used as the first reference signal. For example, synchronization or reference signals such as SSB, CSI-RS, or DM-RS can be used.

[0177] Note that according to an embodiment, the third time point and the desired duration are derived from parameters (i.e., pre-configured parameters) known at the transceiver and another transceiver. Information related to the difference between the fifth time point and the second time point is also available at the transceiver and another transceiver. According to an embodiment, the time information associated with the fifth time point includes configuration information for selecting a (second) cyclic shift. This second cyclic shift can be used by another transceiver.

[0178] Regarding the information related to the fifth time point, it should be noted that this information includes the definition of two values, specifically the timing advance value and the OFDM symbol timing, to maintain the time constraint. Note that this is the information used to determine the third time point. According to an embodiment, the information related to determining the third time point can be pre-configured or received from the network, gNB, or location server. Note that the third time point depends on the system timing constraint or is set according to the timing advance constraint. According to an embodiment, the third time point is derived from the recovered OFDM symbol timing and the timing advance setting.

[0179] According to an embodiment, a positioning node is provided, such as a location server, a location management function (LMF), or a local location function at a transceiver (10), BS, or RSU. It is configured to: request a measurement report from the transceiver (10); receive information about the arrival time measurement of the second reference signal (RS2) from the transceiver (10); and calculate the ranging between the transceiver (10) and the transceiver (12) based on the measured arrival time received from the transceiver (10) and the information about the third or fifth time point (t5).

[0180] According to a further embodiment, the transceiver (10) is configured to calculate the arrival time of the second reference signal (RS2) based on measurements performed by another transceiver (10), or perform a measurement of the arrival time of the second reference information (RS2); and calculate and / or report the ranging based on the calculated or measured arrival time and the information about the third time point or the fifth time point (t5), without receiving or accessing a measurement report from the transceiver (12) that transmits the second reference signal (RS2).

[0181] According to an embodiment, the first and / or second reference symbols are configured by the network or the transceiver with respect to one of the following factors: position in the frame, slot number and OFDM symbol position in the slot, number of OFDM symbols for the RS, RS sequence type and RS sequence parameters, bandwidth, center frequency, COMB factor, sequence ID, etc.

[0182] Regarding Figure 6 , device-to-device round-trip measurements (one initiator and one responder) can be discussed. These devices are labeled with reference numerals 10 and 12, where 10 is the initiator and 12 is the responder. Both communicate with the gNB, for example, to receive a configuration, where the configuration can be "semi-static" or valid for a configurable duration. The gNB is labeled with reference numeral 14.

[0183] Two devices 10 and 12 perform RTT measurements by sending an RS from the first device (initiator) to the second device, and the second device responds with an RS sent to device 1.

[0184] · The network (or the first device in the case of sidelink operation) configures the position of the RS in the frame (slot number and OFDM symbol position in the slot, number of OFDM symbols), and the RS parameters (bandwidth, center frequency, COMB factor, number of symbols, sequence ID, etc.).

[0185] The configuration can be

[0186] ο semi-persistent, or

[0187] ο pre-configured, and the RS is activated by a trigger, or

[0188] ο pre-configured and activated when a predefined condition becomes effective (e.g., the responder detects a signal from the initiator)

[0189] · The configuration information can include TA settings. This TA defines the transmission time t3 framed relative to the recovered OFDM symbols.

[0190] · The network configures a constant response time for device 2

[0191] · The initiator sends a reference signal

[0192] · The responder performs a ToA measurement on the signal received from the initiator

[0193] · From the measured ToA, the responder calculates the effective transmission time t5

[0194] · Using the transmission time (t3) according to the TA settings, the responder calculates the cyclic shift t CS = t5 - t3, and applies this cyclic shift to the configured RS before transmitting the RS at time t3.

[0195] According to a further embodiment, one initiator and several responders can be used. As Figure 7a shown.

[0196] The initiator UE is labeled with reference numeral 10, where the responder UEs are labeled with reference numerals 12a, 12b, and 12c. Note that the UEs here can be model UEs, such as cars or general RSUs (roadside units). Therefore, each transmitter sends a signal (equivalent to "spatial multiplexing"), where CS-MOX is used for answering. This embodiment is characterized by the following steps:

[0197] · One initiator (e.g., a mobile device)

[0198] · The signal sent by the initiator is received by several (k) "responders"

[0199] · Each responder can use the same resources for responding, or use different resources (e.g., different COMB offsets or different OFDM symbols).

[0200] · If the signals use the same resources, the signals of the responders are distinguished as follows

[0201] ο Use different cyclic shifts ("cyclic shift multiplexing" = CS multiplexing (CS mux)).

[0202] ο Alternatively: Use different sequences ("code division multiplexing").

[0203] · Each responder calculates the CS (second CS in the case of CS mux) to adjust the effective ToT (t 5,k )

[0204] · The initiator receives multiple responses and can calculate the distance to each responder.

[0205] · If the location of the RSU is known, the initiator may be able to calculate its location or ranging relative to the RSU or several RSUs.

[0206] According to an embodiment, this means that the first reference signal transmitted by the initiator 10 includes the initiator signal for initiating position measurement. In addition, the transceiver (responder) can use differential cyclic shifts for the response signals (second reference signal, third reference signal...).

[0207] Regarding Figure 6 and the embodiment discussed in FIG. 7 shows that the principles discussed can be used for sidelink communication and thus for position determination in the sidelink. Preferably, but not necessarily, configuration information from the gNB or the positioning server can be used. However, according to a further embodiment, this configuration information can also be pre-configured.

[0208] According to an embodiment, all the RSUs 12a, 12b, and 12c can use the same resources (same RE) and transmit using the same OFDM symbol at almost the same time. Each RSU also selects the same sequence but applies a different cyclic shift (CS) to the symbol. If the sequence is related to the (unshifted) sequence, this shifts the correlation peak in time.

[0209] If the RSUs use the same RE, the signals will be superimposed and the correlator output includes several peaks.

[0210] This is shown in Figure 7b In Figure 7b 's example, it is assumed that three roadside units with different distances to the UE 10 are used (see Figure 7a) Assume that the RSU is synchronized with the network and sends signals almost at the same time, but each RSU uses a different CS. The signals will arrive with a time offset according to different distances d1, d2, and d3. Assume that multipath propagation exists. Therefore, after the first arrival path (FAP), several multipath components may arrive. The correlator output will include correlation peaks associated with each RSU and associated multipath components (indicated as triangles and additional correlation peaks in the figure). The parts of the correlation functions associated with different RSUs are marked with different colors. The position of the correlation peak depends on the distance and the CS configured for each RSU. There are two possible implementations:

[0211] · Each RSU k reports the difference of t5–t2. This is not within the scope of the present invention.

[0212] · Each RSU k is configured with a first CS1 and calculates a second CS2 based on the measured t 2,k and the desired t 5,k

[0213] · t CS2,k = t 5,k – t 2,k – t CS1,k – dt const

[0214] where

[0215] t 2,k is the measured ToA of RSU k

[0216] t CS1,k is the configured CS1 of RSU k

[0217] dt const is the configured time offset (e.g., n*t Sym – TA).

[0218] Alternatively, t CS2,k can be calculated by

[0219] t CS2,k = t 5,k – t 3,k + t CS1,k

[0220] where

[0221] t 3,k is the transmission time configured according to the network symbol timing requirement.

[0222] Due to the CAZAC (Constant Amplitude Zero Auto - Correlation) property of the Zadoff - Chu sequence for SRS, signals can be distinguished even if the received signals have a high level difference. To evaluate the feasibility and signal requirements, we considered numerical examples.

[0223]

[0224] In particular, in this embodiment, the RSU may be configured with a sequence number on which the RSU will provide a response. For example, the UE receives auxiliary data about the initiating signal to which the RSU should respond.

[0225] Regarding Figure 8 , CS - Mux for answering will be discussed. Figure 8 The initiating UE 10 is shown, here it is the roadside unit, which sends signals to several other UEs 12a, 12b, and 12c. The signals sent by the initiator are received by several (k) "responders" (e.g., UEs in cars)

[0226] · Each responder uses the same resources for response

[0227] · The signals of the responders are distinguished by

[0228] ο Using different cyclic shifts ("Cyclic Shift Multiplexing" = CS mux)

[0229] ο Alternatively: Using different sequences ("Code Division Multiplexing")

[0230] · Each responder can be configured with a different CS1

[0231] · Each responder calculates CS2 (the second CS in the case of CS mux) to adjust the effective ToT (t 5,k )

[0232] · The initiator (e.g., RSU) calculates ranging and can report the ranging to the network (LMF)

[0233] This means that, according to the embodiment, the first reference signal is sent as the initiating signal, here sent by the transceiver 10, where multiple transceivers receiving the first reference signal use different cyclic shifts defined by different cyclic shift values to send their corresponding second reference signals. Thus, by using CS - Mux for answering, the response consists of the sum of several signals that only have different cyclic shifts. Alternatively, different sequences or resources are used as the response of the initiator.

[0234] Regarding the LMF entity, it should be noted that, according to the embodiment, the LMF / Localization Server can calculate the location as follows:

[0235] · Request a measurement report from at least one initiator; and

[0236] · Receive ToA (or Rx-Tx time difference) measurements from the initiator,

[0237] · Do not receive a measurement report from the responder;

[0238] · And calculate the ranging based on the measured ToA and the information of the responder's transmission time.

[0239] Similarly, the position determination can be performed by the initiator entity as follows:

[0240] · Calculate the ToA (or Rx-Tx time difference) measurements of the initiator,

[0241] · Do not receive a measurement report from the responder;

[0242] · And calculate the ranging based on the measured ToA and the information of the responder's transmission time.

[0243] The common point of both is that the position can be calculated without a measurement report from the responder, which means that they do not receive a measurement report from the responder (i.e., the transceiver that implies the cyclic shift value). This advantageously enables the transponder applying the cyclic shift value to use a very low-power reference signal because only the signal itself is sent without sending the content of the signal. This enables large ranging to be determined due to the power limitation of the signaling, especially because there is no need to exchange reports.

[0244] When the UE is in the RRC connected state, the configuration of the resources for sending the reference signal to the UE can be sent unicast or broadcast to the UE, or the configuration can be pre-configured in the UE itself. The configuration can be provided to the UE by a network entity (such as the LMF or the NG-RAN node), or the configuration can be exchanged between UEs in the sidelink mode.

[0245] According to an embodiment, the transmission between the target UE and the NG-RAN / network node can be as follows. The initiator is the network node and the responder is the UE. Here, the UE can be configured with one or more resources, where the UE listens to the downlink reference signal sent by the network node. The UE may be able to use the configuration to obtain at least the time and / or frequency resources at which the UE expects to receive the downlink reference signal. The UE may additionally be able to obtain additional information about the downlink reference signal, such as the transmission comb, the transmission comb offset, the information describing the reference signal (such as the ID for generating the sequence, etc.), the ARFCN, the position of the network node, and so on.

[0246] According to a further embodiment, the initiator is a UE, where the responder is one or more network nodes. Here, the UE or a group of UEs can be configured with resources for the UE to send uplink resources, and the UE is provided with a configuration where it can expect to find a downlink response. In response to the uplink signal sent by the UE, the network sends a downlink signal on the downlink resources mapped to the uplink resources. The downlink signal can be cyclically shifted in response to the reception time of the uplink signal detected at the TRP.

[0247] The UE can be configured with one or more resources where it is expected that the UE searches for a response from a network node.

[0248] As already described above, the above method can also be applied to sequential transmission. Figure 9 An initiator 10 and three responder UEs 12a, 12b, and 12c are shown, all communicating via sidelink. According to an embodiment, the UEs (responders 12a, 12b, 12c) are configured with one or more resources where the UEs listen for sidelink reference signals sent by another UE (initiator 10). When the sidelink UE is in the RRC connected state with a network node, the configuration can be provided by the network node, or the configuration can be a default configuration pre-configured by the network for use in certain scenarios (e.g., when the UE is out of coverage or in a partial coverage area). Additionally, the UEs are configured with a second resource where the responder UEs 12a, 12b, 12c respond to the reference signals received from the initiating UE.

[0249] Here, different cases can be distinguished according to different embodiments.

[0250] Case 1: One initiating UE, one or more responding UEs

[0251] In one example, the UE is provided with at least one resource configuration where the initiator transmits a reference signal. The reference signal can be received by one or more UEs. Regarding the configuration of the resources where the UE should expect a response from one or more responding UEs, the UE can be configured by the network within coverage, or can be pre-configured by the network before going out of coverage.

[0252] A typical use case is a scenario where an LCS client resides in a UE and the responders may be time-fixed UEs. The location of the responders is available to the target UE (initiator). The responders can cyclically shift their reference signals based on the configuration information and the time they receive the signal sent by the initiator.

[0253] According to an example, the resource configuration for transmitting the initiating reference signal can be mapped to the resource configuration for receiving the response signal. In this example, one or more UEs can be separated by sequences, resources, or cyclic shift values. The initiating UE can identify the responding UE by the sequence used. The sequence can be derived based on the identifier of the responding UE. Alternatively or additionally, the responding UE can be identified by the time or frequency resources used by the UE for the response, which can also be based on an identifier used to identify the UE or the UE's location or a region in the network. For example, the time / frequency resources used by the UE for the response can be derived based on the RNTI or the serving cell or some identifier that the initiator can associate with the responding UE. Additionally, the network can provide additional information related to the responding UE in one or more messages sent to the initiating UE. Alternatively, such messages can be exchanged between the involved UEs in the sidelink (e.g., using the PC5 interface or using one or more high-layer signaling protocols conveyed via the PC5 interface). Such messages can include one or more information about the responding UE, such as its location, whether it is a fixed UE or a mobile UE, its transmission characteristics, such as antenna location, antenna orientation, antenna pattern, etc.

[0254] Responding UEs can be separated from each other by any combination of sequences, time, and frequency. For example, a group of UEs located in a given V2X area can use the same time or frequency resources, and each individual UE can use a different sequence to identify itself.

[0255] Furthermore, if the responding UE receives an initiating signal with certain characteristics, it can respond only to the transmission received from the initiator. According to this example, if the following conditions are met, the UE can respond to a downlink signal sent by the network

[0256] 1) The RSRP measured on the downlink resource is higher than a certain threshold.

[0257] 2) The RSRP measured on the downlink resource is higher than a certain threshold and lower than a second threshold.

[0258] 3) The reception time measured on the downlink resource is higher than a certain configured time offset from a reference time point.

[0259] 4) The reception time measured on the downlink resource is higher than a certain value and lower than a certain value relative to the reference time point.

[0260] 5) One of the combinations of the above conditions.

[0261] Case 2: One responding UE, one or more initiating UEs

[0262] In one example, both the initiating UE and the responder may be in an in-coverage scenario. In another example, the initiating UE may be in an in-coverage scenario while the responder may be in a partially in-coverage scenario. When at least the initiator is in an in-coverage scenario, the initiating UE may transmit the ranging between the initiator and the responder to a network entity to calculate the Position

[0263] Multiple initiating UEs within the network coverage may perform ranging on a responder UE (which may be in-coverage, out-of-coverage, or partially in-coverage) and send the ranging between the initiator and the responder UE to a network entity. The network entity may use the ranging obtained from different initiators to locate the UE.

[0264] According to an embodiment, in the case where one or more fixed nodes (such as RSU) as shown in Figure 10 send an initiator request to the target UE, the scenario as shown in Figure 9 may be enhanced.

[0265] The initiating UEs are labeled with reference numerals 10a, 10b, and 10c, where the target UE / responder UE is labeled with reference numeral 12. The target UE (UE1) to be located may be in a partially in-coverage scenario or an out-of-coverage scenario. For other UEs, the location may be known. If the location is known, the UE may act as an "anchor" to determine the location of other devices. Multiple (anchors 10a, 10b, 10c) UEs with a signaling connection to the LMF may perform ranging on UE1 12 and send the ranging between the anchor UEs 10a, 10b, 10c and UE1 12 to the LMF. In addition, the anchor UE may signal to the LMF any one of the following: anchor location, timestamp, antenna direction, antenna pattern, RSRP measurement, motion profile of the anchor, etc.

[0266] The process is shown in FIG. 11. According to Figure 11a the embodiment, four steps 102, 104, 112, and 114 may be performed.

[0267] 102 refers to obtaining a reference signal configuration (transmission and reception) for arrangement to the target UE / responder UE.

[0268] 104 refers to transmitting an initiator reference signal on a resource configured for initiating the reference signal (reference signal 1).

[0269] At the responder UE, the next step 112 is performed. Step 112 involves receiving a cyclically shifted reference signal from the target UE and determining the target ranging to the target UE. Note that between steps 104 and 112, the target UE / responder UE may perform its steps of receiving the reference signal and sending the cyclically shifted reference signal. In the final step 114, information is provided to the LMF, which may include at least the ranging to the target UE.

[0270] Step 116 is optional and is to provide additional information (such as location) about the anchor UE to the LMF.

[0271] At the target UE / responder UE, a method including steps 105, 107, and 109 is performed. The method is as Figure 11b shown. As indicated by the reference numerals, step 105 is arranged between steps 104 and 112.

[0272] In step 105, a reference signal configuration for arranging with the anchor UE is obtained (sent and received). This step is equivalent to step 102. In the next step 107, the initiator reference signal (first reference signal) is received on the resource for initiating the reference signal configuration.

[0273] In the final step 109, the step of sending a cyclically shifted reference signal (reference signal 2) to the anchor UE on the configured resource is performed, where the cyclic shift is based on a predefined response time and the time of receiving the initiator reference signal from the anchor UE. This step is marked by reference numeral 105.

[0274] Alternatively, one of the UEs may process the ranging information to determine the UE location and provide the UE location to the LCS client. The UE that processes the ranging information between the target UE and one or more anchor UEs may be one of the anchor UEs itself or may be a separate node. If one of the anchor nodes or another UE having a signaling connection with the anchor node is configured to calculate the location, one of the anchor nodes may calculate the UE location.

[0275] Figure 12 This principle is shown, Figure 12 showing a combination of three initiator UEs 10a, 10b, and 10c and a responder UE 12. In Figure 10 , all three UEs 10a, 10b, and 10c can communicate with the LMF 15.

[0276] An embodiment relates to a user equipment, which includes one of the above responder transceivers, where the other transceiver is part of a UE (sidelink communication) or part of a base station.

[0277] Another embodiment relates to a system that includes at least a user equipment forming a responder UE and another user equipment and / or a base station that includes another transceiver and forms an initiator UE.

[0278] Further embodiments will be discussed below.

[0279] The main embodiment relates to a device that supports RTT measurement. The device can be defined as follows:

[0280] · A first device (“responder”) is configured to measure the ToA of a received signal transmitted by a second device (“initiator”)

[0281] · The first device is configured to transmit a reference signal (RS) useful for the ToA measurement in response to the signal received from the second device

[0282] · The device determines a first ToT (t3) based on the recovered OFDM symbol timing of the received signal and the desired TA value

[0283] · The device determines a second ToT (t5).

[0284] · The device calculates the difference t CS = t5 – t3

[0285] · Based on the calculated t CS , CS is applied to the configured RS before the transmission at time t3

[0286] Optional functions of this device include:

[0287] · According to an embodiment, the responder receives the configuration to be applied and generates a constant delay t5 – t2 (the responder can receive the configuration from a location server / LMF or serving BS or coordinating UE)

[0288] · According to an embodiment, the desired constant delay is derived from parameters known at the entity (such as NW) that determines the ranging and the responder device (UE).

[0289] For example, t3 - t2 = n * t Sym – TA

[0290] where

[0291] οn is derived from the scheduling of the signal (the time slot and the symbols in the time slot)

[0292] οTA is set by the network (and can remain constant before an update (“semi-persistent”)

[0293] · According to an embodiment, in addition to the CS derived from the difference t5 – t3, the network can also configure additional CS to distinguish responders using the same RE

[0294] Another embodiment relates to a system including an initiating UE and a responding UE, wherein within the system, the initiating UE includes a ranging determination device or is connected to a ranging determination device. This embodiment can be defined as follows: Initiator: The initiator transmits and its Tx signal is used as a reference for one or more responders. The responder adjusts its timing according to the main method. The ranging determination entity is the entity that determines ranging using the known round-trip time. This can be the initiator, but not necessarily the initiator (for example, there may be a scenario where the initiator and other devices measure the responder's signal).

[0295] As described above, multiple responding UEs can respond to the initiator's request. It should be noted that this also implies sequential operation (initiator request-response sequence and / or several responders respond in sequence). The responding UE can use the CS-Mux described above. This combination helps to avoid interference due to possible collisions from different responders. For example, the responder generates a response for each initiator and adds these responses before transmission.

[0296] General

[0297] The embodiments of the present invention have been described in detail above, and the corresponding embodiments and aspects can be implemented individually, or two or more embodiments or aspects can be implemented in combination.

[0298] According to an embodiment, a wireless communication system can include a terrestrial network or a non-terrestrial network, or a network or network segment using an airborne vehicle or a spaceborne vehicle as a receiver, or a combination thereof.

[0299] According to an embodiment, the user equipment UE described herein can be one or more of a power-constrained UE or a handheld UE, such as a UE used by a pedestrian, and is referred to as a vulnerable road user VRU or a pedestrian UE (P-UE), or a portable or handheld UE used by public safety personnel and first responders, also referred to as a public safety UE (PS-UE) or an IoT UE. For example, a sensor, an actuator, or a UE provided in a campus network to perform repetitive tasks and receive inputs from a gateway node at periodic intervals, or a mobile terminal, a fixed terminal, a cellular Internet of Things IoT-UE, a vehicle UE or a vehicle group leader (GL) UE or IoT, or a narrowband IoT device, or a WiFi non-access point station (non-AP STA), such as 802.11ax or 802.11be, or a ground vehicle, or an air vehicle, or a drone, or a mobile base station, or a roadside unit, or a building, or any other item or device equipped with a network connection that enables the item / device to communicate using a wireless communication network, such as a sensor or an actuator, or any other item or device provided with a network connection that enables the item / device to communicate using a sidelink wireless communication network, such as a sensor or an actuator, or any network entity with sidelink capabilities.

[0300] The base station BS described herein can be implemented as a mobile or non-mobile base station and can be a macrocell base station, or a small cell base station, or a central unit of a base station, or a distributed unit of a base station, or an Integrated Access and Backhaul (IAB) node, or a roadside unit, or a UE, or a group leader GL, or a relay, or a remote radio head, or an AMF, or an SMF, or a core network entity, or a mobile edge computing entity, or a network slice in the NR or 5G core context, or a WiFi AP STA (such as 802.11ax or 802.11be) or any transmission / reception point (TRP) such that an item or device can communicate using a wireless communication network, and the item or device is provided with a network connection to communicate using a wireless communication network.

[0301] Although some aspects of the described concepts have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of method steps also represent a description of the corresponding block or item or feature of the corresponding apparatus.

[0302] The various elements and features of the present invention can be implemented in hardware using analog and / or digital circuits, in software, by executing instructions with one or more general or special-purpose processors, or as a combination of hardware and software. For example, embodiments of the present invention can be implemented in the environment of a computer system or another processing system. Figure 13 An example of a computer system 600 is shown. These units or modules and the steps of the methods performed by these units can be executed on one or more computer systems 600. The computer system 600 includes one or more processors 602, such as a dedicated or general-purpose digital signal processor. The processor 602 is connected to a communication infrastructure 604, such as a bus or a network. The computer system 600 includes a main memory 606, such as a random access memory RAM, and an auxiliary memory 608, such as a hard disk drive and / or a removable storage drive. The auxiliary memory 608 can allow computer programs or other instructions to be loaded into the computer system 600. The computer system 600 can also include a communication interface 610 to allow software and data to be transferred between the computer system 600 and external devices. The communication can be electronic, electromagnetic, optical, or other signals that can be processed by the communication interface. The communication can use wires or cables, optical fibers, telephone lines, cellular phone links, RF links, and other communication channels 612.

[0303] The terms "computer program medium" and "computer-readable medium" generally refer to tangible storage media, such as a removable storage unit or a hard disk installed in a hard disk drive. These computer program products are devices for providing software to the computer system 600. The computer program, also known as computer control logic, is stored in the main memory 606 and / or the auxiliary memory 608. The computer program can also be received via the communication interface 610. When the computer program is executed, it enables the computer system 600 to implement the present invention. In particular, when the computer program is executed, the computer program enables the processor 602 to implement the processes of the present invention, such as any of the methods described herein. Therefore, such a computer program can represent the controller of the computer system 600. In the case of implementing the present disclosure using software, the software can be stored in a computer program product and loaded into the computer system 600 using a removable storage drive, an interface (such as the communication interface 610).

[0304] Implementations in hardware or software can be performed using digital storage media, such as cloud storage, floppy disks, DVDs, Blu-rays, CDs, ROMs, PROMs, EPROMs, EEPROMs, or flash memories, on which electronically readable control signals are stored, which cooperate or are capable of cooperating with a programmable computer system to perform the corresponding methods. Therefore, the digital storage media can be computer-readable.

[0305] Some embodiments according to the invention include a data carrier having an electronically readable control signal, which is capable of cooperating with a programmable computer system to perform one of the methods described herein.

[0306] Generally, embodiments of the invention may be implemented as a computer program product having program code for performing one of the methods when the computer program product is run on a computer. The program code may be stored, for example, on a machine-readable carrier.

[0307] Other embodiments include a computer program stored on a machine-readable carrier for performing one of the methods described herein. In other words, thus, embodiments of the method of the invention are a computer program having program code for performing one of the methods described herein when run on a computer.

[0308] Thus, further embodiments of the method of the invention are a data carrier, or a digital storage medium or a computer-readable medium, on which a computer program for performing one of the methods described herein is recorded. Thus, further embodiments of the method of the invention are a data stream or a signal sequence representing a computer program for performing one of the methods described herein. The data stream or signal sequence may be configured, for example, to be transmitted via a data communication connection (such as via the Internet). Further embodiments include a processing device, such as a computer or a programmable logic device, which is configured or adapted to perform one of the methods described herein. Further embodiments include a computer on which a computer program for performing one of the described methods is installed.

[0309] In some embodiments, a programmable logic device, such as a field programmable gate array, may be used to perform some or all of the functions of the methods described herein. In some embodiments, the field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. Generally, these methods are preferably performed by any hardware device.

[0310] The above embodiments are only used to illustrate the principle of the invention. It should be understood that modifications and variations of the arrangements and details described herein will be apparent to other technicians in the art. Therefore, the intention is only limited by the scope of the upcoming patent claims, and not by the specific details presented by the description and interpretation of the embodiments herein.

Claims

1. A transceiver (12), configured to: Receive a first reference signal (RS1) at a second time point (t2), the first reference signal (RS1) being transmitted by another transceiver (12) at a first time point (t1); and Transmit a second reference signal (RS2), where the second reference signal (RS2) is set to be transmitted at a third time point, wherein, Modify the second reference signal by means of a cyclic shift (CS) defined by a cyclic shift value (T CS ); wherein, the cyclic shift value (t CS ) is derived from a second time point (t2) (measured time of arrival (ToA)) of a received first reference signal (RS1) and time information associated with a fifth time point (t5).

2. The transceiver (12) according to claim 1, wherein a second reference signal (RS2) will be received by a receiver or another transceiver (12), and the receiver or another transceiver performs a ToA measurement based on the cyclic (cross) - correlation of the received signal with a configured (unmodified) transmitted reference signal, thereby generating a sixth time point (t6); wherein the difference between the sixth time point (t6) and a fifth time point (t5) represents the time - of - flight (ToF).

3. The transceiver (12) according to claim 1 or 2, wherein, The receiver or the second transceiver is able to derive the sixth time point (t6) from the transmitted signal, at which sixth time point (t6), assuming cyclic correlation, the second reference signal (RS2) can be detected by the receiver or another transceiver (12), wherein the sixth time point (t6) is different from a fourth time point (t4), and the fourth time point (t4) represents the time window of the start of the OFDM symbol at which the second reference signal (RS2) is received without cyclic shift; and / or wherein the difference between the fourth time point (t4) and the sixth time point (t6) depends on the applied cyclic shift, and the difference is unknown and / or does not require further processing at the receiver; and / or wherein the difference between the sixth time point (t6) and the associated fifth time point represents the time - of - flight (ToF) between the transmitter and the receiver; wherein if no cyclic shift is applied or if the cyclic shift value is set to zero, the fourth time point and the sixth time point are the same.

4. The transceiver (12) according to any one of the preceding claims, wherein the second reference signal (RS2) modified by cyclic shift is modified such that the OFDM symbol is cyclically shifted before cyclic prefix insertion; wherein, The cyclic prefix is a copy of the end of the OFDM symbol.

5. The transceiver (12) according to any one of the preceding claims, wherein the cyclic shift is applied in the time domain or in the frequency domain; Among them, Applying the cyclic shift in the frequency domain using the following formula S (n) = R (n) · e jαn , where where N is the FFT length n is an index, n ∈ [0, (N - 1)] R (n) is the frequency-domain representation of RS without cyclic shift, where R (n) = fft(r (n) ), and r (n) is the time-domain signal of RS without CP t CS is the target cyclic shift (in seconds) T0 is the sampling period in seconds S (n) is the frequency-domain representation of RS with cyclic shift.

6. The transceiver (12) according to any one of the preceding claims, wherein, The time information associated with the fifth time point (t5) includes the expected duration between the fifth time point (t5) and the second time point (t2); and / or wherein the difference between the fifth time point (t5) and the third time point (t3) represents the required cyclic shift value, and the third time point (t3) is selected according to network synchronization requirements and the scheduling of the second reference signal (RS2).

7. The transceiver (12) according to any one of the preceding claims, wherein the third time point (t3) can be derived from the measured second time point (t2) t3 = t2 + t TX – TA; Among them, t TX Indicates the scheduling of the OFDM symbol for transmitting the second reference signal (RS2) scheduled relative to the first reference signal (RS1), and the TA is set by the network or remains constant ("semi-persistent") until updated.

8. The transceiver (12) according to any one of the preceding claims, wherein, The third time point (t3) is derived from other synchronization or reference signals, such as SSB, CSI - RS, DM - RS, PRS, SRS, SL - PRS, sidelink synchronization signal (SLSS); and / or wherein the reference signal includes synchronization signals, such as SSB, CSI - RS, DM - RS, PRS, SRS, SL - PRS, sidelink synchronization signal (SLSS).

9. The transceiver (12) according to any one of the preceding claims, wherein the desired duration between the fifth time point (t5) and the second time point (t2) is constant or semi-constant (constant for a configurable number of transmissions or duration), or is derived from other parameters such as the transmitter ID; and / or wherein the desired duration is configured or pre-configured.

10. The transceiver (12) according to any one of the preceding claims, wherein, (The required) cyclic shift value is calculated from the difference between the fifth time point (t5) and the third time point (t3) t CS = t5 - t3 or if the difference t5 - t3 is less than 0 or greater than or equal to t Sym , t CS = mod(t5 - t3, t Sym ) where t Sym is the duration of an OFDM symbol without a cyclic prefix.

11. The transceiver (12) according to any one of the preceding claims, wherein, The transceiver (12) is configured with a second cyclic shift value, or the second cyclic offset value is derived from other configuration parameters such as the antenna port, wherein the second cyclic shift value is added to the first cyclic shift value; and / or wherein the second cyclic shift value is encoded differently compared to the first cyclic shift value; and / or wherein different cyclic shifts (CS) are used to send different second reference signals (RS2) to different other transceivers.

12. The transceiver (12) according to any one of the preceding claims, wherein, A plurality of transceivers (12) use the same resources in time and frequency and use the desired difference between the fifth time point (t5) and the second time point (t2); and / or wherein different cyclic shifts are configured for a plurality of transmitters, thereby generating a plurality of correlation peaks, representing a sixth time point (t6) for each transmitted signal; and / or wherein the configured values are selected to allow the distribution between the correlation peaks to the associated transceivers.

13. The transceiver (12) according to any one of the preceding claims, wherein, A plurality of transceivers (12) respond to a first reference signal (RS1) transmitted by another transceiver (10) (initiator), and the cyclic shift (CS) depends on responder-specific information or responder / anchor ID information.

14. The transceiver (12) according to any one of the preceding claims, wherein, The third time point (t3) and / or the desired duration are derived from parameters known at the transceiver (12) and at another transceiver (12); and / or wherein information related to the difference between the fifth time point and the second time point (t2) is available at the transceiver (12) and at another transceiver (12).

15. The transceiver (12) according to one of the preceding claims, wherein, The time information associated with the fifth time point (t5) includes configuration information for selecting the (second) cyclic shift; and / or wherein the desired duration depends on the configuration information, and the configuration information includes information for calculating or selecting the cyclic shift (CS) or ranging / interval; and / or wherein the information related to the fifth time point and / or the third time point (t3) includes the definition of two values, in particular the value for timing advance and the OFDM symbol timing for maintaining timing constraints; and / or wherein the information related to determining the third time point (t3) or the third time point (t3) is pre-configured or received from the network, gNB or positioning server; and / or wherein the third time point (t3) depends on system timing constraints, or wherein the third time point (t3) is set according to timing advance constraints, or wherein the configured third time point (t3) is derived from the recovered OFDM symbol timing and timing advance setting.

16. The transceiver (12) according to any one of the preceding claims, wherein, The first reference signal and / or the second reference signal (RS2) is configured by the network or the transceiver (12) with respect to one of the following factors: position in a frame, slot number and OFDM symbol position in a slot, number of OFDM symbols, RS sequence type and RS sequence parameters, bandwidth, center frequency, COMB factor, sequence ID, etc.

17. The transceiver (12) according to any one of the preceding claims, wherein, The third time point (t3) represents the time of the first sample of the modified OFDM symbol, where the modification results in a valid time point defined by the fifth time point (t5); and / or wherein the transmitter is configured to calculate the valid third time point (t3) based on the second time point (t2) and the cyclic shift (CS) and / or based on the desired duration between the valid third time point (t3) and the second time point (t2).

18. The transceiver (12) according to any one of the preceding claims, wherein, The transceiver (12) is configured to determine the (valid) second time point (t2).

19. The transceiver (12) according to claim 18, wherein, The transceiver (12) is configured to perform measurements to determine the second time point (t2), or wherein the determination of the third time point uses pre-configured information (e.g., system timing boundary).

20. The transceiver (12) according to any one of the preceding claims, wherein, Considering the desired duration between the second time point and the fifth time point (t5), the time of flight and / or the round-trip time is computable based on the difference between the sixth time point and the first time point (t1).

21. The transceiver 12 according to any one of the preceding claims, wherein the first reference signal (RS1) received at the second time point (t2) includes a predetermined time reference point or an OFDM symbol with a cyclic prefix.

22. The transceiver (12) according to any one of the preceding claims, wherein, The first reference signal (RS1) includes an initiating party signal for initiating position measurement; and / or wherein the first reference signal (RS1) is sent as an initiating party signal to several transceivers using different cyclic shift (CS) values of the second reference signal (RS2).

23. The transceiver (12) according to any one of the preceding claims, wherein, The transceiver (12) (responding party) uses a different cyclic shift for the third reference signal of the second other transceiver (12) (initiating party).

24. A transceiver (10) configured to: calculate the arrival time of the second reference signal (RS2) based on measurements performed by another transceiver (10), or perform measurements of the arrival time of the second reference signal (RS2); and calculate and / or report ranging based on the calculated or measured arrival time, based on information regarding the third time point or the fifth time point (t5), without receiving or accessing a measurement report from the transceiver (12) that transmits the second reference signal (RS2).

25. A user equipment, comprising a transceiver (10, 12) according to any one of the preceding claims, wherein, Another transceiver (10, 12) is part of a base station (14).

26. A user equipment, comprising a transceiver (10, 12) according to any one of claims 1 to 24, wherein, Another transceiver (12) is part of another user equipment, where the user equipment and the other user equipment communicate with each other using sidelink communication.

27. A user equipment, comprising a transceiver (12) according to any one of claims 1 to 24, wherein, The user equipment belongs to a group including: - User Equipment, UE, - Power-constrained UE, - Handheld UE, such as a UE used by a pedestrian and referred to as a Vulnerable Road User VRU, or a Pedestrian UE, P-UE, or a wearable or handheld UE used by public safety personnel and first responders and referred to as a Public Safety UE, PS-UE, - IoT UEs, such as sensors, actuators, or UEs provided in a campus network, to perform repetitive tasks and requiring inputs from the gateway node at periodic intervals, - Mobile terminals, - Fixed terminals, - Cellular IoT-UEs, - Vehicle UEs, - Group Leader GL, UE, - IoT, or Narrowband IoT, NB-IoT, devices, or WiFi Non-Access Point Stations, non-AP STAs, such as 802.11ax or 802.11be, - Ground vehicles or aerial vehicles, - Base stations (14), such as e gNBs or eNBs, - Drones or mobile base stations (14), - Road Side Units or buildings, or any other item or device provided with a network connection enabling the item / device to communicate using a wireless communication network, such as sensors or actuators, - Any other item or device provided with a network connection enabling the item / device to communicate using a sidelink wireless communication network, such as sensors or actuators, or any network entity supporting sidelink.

28. A system comprising a user equipment according to claim 25 and another user equipment according to claim 26 or a base station (14), wherein, Another user equipment of the base station (14) includes other transceivers.

29. The system according to claim 28, further comprising an additional user equipment according to claim 25 or 26, wherein both the user equipment and the additional user equipment receive a first reference signal (RS1).

30. A positioning node, particularly a location server, location management function (LMF), or local location function at a transceiver (10) or BS or RSU, configured to: Request a measurement report from the transceiver (10); Receive information about the time-of-arrival measurement of a second reference signal (RS2) from the transceiver (10); Calculate the ranging between the transceiver (10) and the transceiver (12) based on the measured time-of-arrival received from the transceiver (10), the known or measured transmission time of RS1, and the difference between the known or configured second time point and the fifth time point.

31. A method for performing positioning, comprising: Calculating the time-of-arrival of a second reference signal (RS2) based on measurements performed by another transceiver (10), or performing a measurement of the time-of-arrival of the second reference signal (RS2); And Calculating the ranging based on the calculated or measured time-of-arrival, without receiving or accessing a measurement report from the transceiver (12) that transmits the second reference signal (RS2), based on the known or measured transmission time of RS1 and the difference between the known or configured second time point and the fifth time point.

32. A method for performing positioning, comprising: Requesting a measurement report from another transceiver (10); Receiving information about the time-of-arrival measurement of a second reference signal (RS2) from another transceiver (10); Calculating the ranging based on the measured time-of-arrival, the known or measured transmission time of RS1, and the difference between the known or configured second time point and the fifth time point.

33. A method for exchanging reference signals, comprising the steps of: Receive a first reference signal (RS1) at a second time point (t2), the first reference signal being transmitted by another transceiver (10) at a first time point (t1); and Transmit a second reference signal (RS2), wherein the second reference signal (RS2) is set to be transmitted at a third time point (t3), and wherein the second reference signal (RS2) is modified by a cyclic shift defined by a cyclic shift value; wherein the cyclic shift value is derived from the second time point (t2) (measured time of arrival (ToA)) of the received first reference signal (RS1) and time information associated with a fifth time point (t5).

34. A computer program for performing the method according to claim 31, 32 or 33 when run on a computer.

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