CN117062165A - Doppler measurement based handoff - Google Patents

Abstract

A method of operating a User Equipment (UE), a user equipment, and a wireless communication system are provided. The method comprises the following steps: transmitting user capability including reception performance information of the UE to the serving cell; receiving, from a serving cell, doppler parameters generated based on user capability and Radio Resource Control (RRC) configuration information; measuring a Reference Signal Received Power (RSRP) and a doppler shift of a reference signal with reference to RRC configuration information; and reporting to the serving cell an rsrp_doppler value, which is a signal metric calculated based on the measured RSRP, the measured Doppler shift, and the Doppler parameter.

Description

Doppler measurement based handoff

Cross Reference to Related Applications

The present application is based on korean patent application No.10-2022-0059171 filed in the korean intellectual property office at 2022, 5 and 13, and korean patent application No.10-2022-0108656 filed in 2022, 8 and 29, the disclosures of which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to handover in wireless communications.

Background

In order to meet the increasing demand for high-speed wireless data communication, fifth-generation (5G) communication technologies have recently been developed and commercialized. To achieve high data rates, 5G communication systems may be implemented to include millimeter wave bands (e.g., 60 gigabyte (60 GHz) bands). In order to mitigate path loss of radio waves in the millimeter wave band and increase propagation distance of radio waves, beam forming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beam forming, massive antenna technology, and the like have been implemented or proposed for 5G communication systems.

Further, in order to improve wireless networks, technologies such as evolved small cell (evolved small cell), advanced small cell, cloud radio access network (cloud RAN), ultra dense network, device-to-device (D2D) communication, wireless backhaul, mobile network (moving network), cooperative communication, cooperative multipoint (CoMP), interference cancellation, and the like have been implemented or proposed for 5G.

Furthermore, hybrid frequency shift keying and quadrature amplitude modulation (FQAM) as Advanced Code Modulation (ACM) schemes, as well as Sliding Window Superposition Coding (SWSC), filter Bank Multiplexing (FBMC) as advanced access technology, sparse Code Multiple Access (SCMA), and the like have been applied or proposed for 5G.

In a 5G wireless communication system, a User Equipment (UE) measures Reference Signal Received Power (RSRP) of a serving cell and/or a neighboring cell (a cell that is located near the UE and to which the UE is not connected), and transmits a measurement result to the serving cell (the cell to which the UE is connected) through a measurement report to perform handover. Further, the serving cell sends the received measurement report to a target cell (e.g., neighboring cell) or core network of the potential handover, and the target cell or core network may determine whether to approve the handover.

However, when the serving cell moves at a high speed like a Low Earth Orbit (LEO) cell, the reception performance of the UE may deteriorate during the handover procedure.

Disclosure of Invention

Embodiments of the inventive concept provide a User Equipment (UE), a communication system including the UE, and methods of operating the UE and the communication system, the UE measuring a Reference Signal Received Power (RSRP) and a Doppler shift of a reference signal and reporting an "rsrp_doppler" value calculated based on the measurement result to a serving cell.

According to an aspect of the inventive concept, there is provided a method of operating a User Equipment (UE), wherein the method comprises: transmitting user capabilities including reception performance information of the UE to the serving cell; receiving, from a serving cell, doppler parameters generated based on user capability and Radio Resource Control (RRC) configuration information; and measuring a Reference Signal Received Power (RSRP) and a doppler shift of the reference signal with reference to the RRC configuration information. The method further includes reporting an rsrp_doppler value to the serving cell, the rsrp_doppler value being a signal metric calculated based on the measured RSRP, the measured Doppler shift, and the Doppler parameter.

According to another aspect of the inventive concept, there is provided a User Equipment (UE) comprising: a memory storing reception performance information of the UE; and a processor configured to transmit a user capability including reception performance information of the UE to the serving cell, receive a Doppler parameter generated based on the user capability and RRC configuration information from the serving cell, measure an RSRP and a Doppler shift of the reference signal with reference to the RRC configuration information, and report an rsrp_doppler value calculated based on the measurement result and the Doppler parameter to the serving cell.

According to another aspect of the inventive concept, there is provided a wireless communication system including: a serving cell configured to be based on user capabilities and RRC

The Doppler parameters generated by the configuration information are sent to the UE; the UE is configured to measure RSRP and Doppler shift of a reference signal with reference to RRC configuration information and report rsrp_doppler values calculated based on the measurement results and Doppler parameters.

Drawings

Embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:

fig. 1 is a diagram illustrating an environment of a terrestrial cell (terrestrial cell) and a Low Earth Orbit (LEO) cell according to an embodiment;

FIG. 2 is a diagram illustrating the environment of a Geostationary Earth Orbit (GEO) cell and a LEO cell, according to an embodiment;

FIG. 3 is a diagram illustrating LEO unit environments at different altitudes according to an embodiment;

fig. 4 is a block diagram illustrating a User Equipment (UE) according to an embodiment;

fig. 5 is a diagram of a signal exchange between a UE and a serving cell according to an embodiment;

fig. 6 is a flowchart illustrating Reference Signal Received Power (RSRP) and doppler shift measurement operations in accordance with an embodiment;

FIG. 7 is a flow chart illustrating an RSRP_Doppler reporting operation according to an embodiment;

FIGS. 8A and 8B are tables showing Delta Doppler according to Doppler shift; and

fig. 9 is a block diagram illustrating a wireless communication system according to an embodiment.

Detailed Description

Hereinafter, embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. Fig. 1 is a diagram illustrating an environment of a terrestrial cell 120 and a Low Earth Orbit (LEO) cell 130 according to an embodiment. User Equipment (UE) 110 may access the network of the wireless communication system by sending and receiving signals with terrestrial cell 120 or LEO cell 130. For example, the wireless communication system may also be referred to as a Radio Access Technology (RAT), and may be, for example, a wireless communication system using a network, such as a 5 th generation (5G) wireless communication system, a Long Term Evolution (LTE) communication system, an LTE advanced communication system, a Code Division Multiple Access (CDMA) communication system, a global system for mobile communications (GSM) communication system, etc., as well as a Wireless Local Area Network (WLAN) communication system or any other wireless communication system.

Hereinafter, the wireless communication system will be described as a 5G communication system, but some embodiments are not limited thereto, and it is apparent that some embodiments may also be applied to next-generation wireless communication systems.

A wireless communication network used in a wireless communication system may support communication for multiple wireless communication devices including UE110 by sharing available network resources.

For example, in a wireless communication network, information may be transmitted in various multiple access schemes such as CDMA, frequency Division Multiple Access (FDMA), time Division Multiple Access (TDMA), orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA, and the like.

Terrestrial cell 120 may generally refer to a fixed station that communicates with UE110 and/or other cells and exchanges data and control information by communicating with UE110 and/or other cells.

Although the terrestrial cell 120 is shown in fig. 1 as a next generation node B (gNB), the term "terrestrial cell" may be interpreted as having a comprehensive meaning that indicates an area or function covered by a node B, an evolved node B (eNB), a sector, a site, a Base Station Controller (BSC), a Base Transceiver System (BTS), an Access Point (AP), a relay node, a Remote Radio Head (RRH), a Radio Unit (RU), or the like.

LEO cell 130 is a non-terrestrial network (NTN) platform and may be different from a Geostationary Earth Orbit (GEO) cell (e.g., 220 in fig. 2). Here, the NTN platform may refer to a mobile communication network using artificial satellites, unlike the terrestrial cell 120. LEO unit 130 may refer to a satellite orbiting the earth at an altitude of 300km to 1500km above the ground. GEO cells orbit the earth at a poster height of 35,786km above the ground and thus may refer to satellites that are observed to be stationary by UEs 110 on the ground.

LEO unit 130 may orbit the earth at high speeds up to 7.56 km/s. Thus, LEO unit 130 may be more affected by doppler shift than ground unit 120. Here, the doppler shift (or doppler effect) may be understood as an effect in which the frequency of a signal transmitted/received between the UE110 and a cell changes when the UE110 or the cell moves. For example, as the distance between UE110 and the cell decreases, the frequency of signals transmitted/received between UE110 and the cell may increase. On the other hand, when the distance between the UE110 and the cell increases, the frequency of signals transmitted and received between the UE110 and the cell may decrease.

For wireless communication between terrestrial cell 120 and LEO cell 130 and UE110, frequency and time synchronization between terrestrial cell 120 and LEO cell 130 and UE110 may be required. Frequency and time synchronization between the terrestrial cell 120 and LEO cell 130 and the UE110 may be difficult as the impact of doppler shift increases. That is, frequency and time synchronization between LEO cell 130 and UE110 may be difficult due to the influence of doppler shift compared to terrestrial cell 120.

Meanwhile, the terrestrial cell 120 and the LEO cell 130 may be connected to the UE110 through a wireless channel, and may provide various communication services to the UE110 through the connected wireless channel. In addition, all user traffic of both the terrestrial cell 120 and the LEO cell 130 may be serviced by a shared channel. Further, the terrestrial cell 120 and the LEO cell 130 may perform scheduling by collecting state information such as a buffer state, an available transmission power state, a channel state, etc. of the UE 110.

UE110 is a user equipment, which may be fixed or mobile, and may refer to any device capable of sending and receiving data and/or control information by communicating with terrestrial cell 120 and LEO cell 130.

For example, UE110 may be referred to as a wireless Station (STA), a Mobile Station (MS), a mobile user equipment (MT), a User Terminal (UT), a UE, a Subscriber Station (SS), a wireless device, a handheld device, and so on.

As such, a wireless communication system according to an embodiment may include satellites, such as LEO cell 130 and terrestrial cell 120. As described above, because LEO cell 130 may be affected by more doppler shift than terrestrial cell 120, the effect of doppler shift may be considered when determining whether to perform a handover of UE 110.

Fig. 2 is a diagram illustrating environments of GEO units and LEO units according to an embodiment.

In fig. 2, a description repeated with the description of fig. 1 may be omitted. Referring to fig. 2, a ue 210 may access a network of a wireless communication system by transmitting and receiving signals with a GEO cell 220 or a LEO cell 230.

As one of the criteria for determining handover of the UE 210, RSRP may be used. In the inventive concept, RSRP may represent a value obtained by the UE 210 measuring the power of a reference signal received from a cell. The higher the RSRP, the greater the strength of the reference signal, and thus, the RSRP may be used to determine whether to perform a handover of the UE 210.

Because GEO cell 220 orbits around the earth according to the orbital velocity of the earth, GEO cell 220 may appear as a fixed point relative to UE 210. Thus, the GEO cell 220 may use RSRP to determine a handover of the UE 210 because the effect of the doppler shift of the GEO cell 220 is insignificant.

However, the LEO unit 230 may orbit the earth at a speed different from the earth orbit speed, and the signal transmitted/received between the LEO unit 230 and the UE 210 may be greatly affected by the doppler shift.

When GEO cell 220 is compared to LEO cell 230 based on RSRP alone, LEO cell 230 may be larger than the RSRP of GEO cell 220 because it may be closer to UE 210. However, because the velocity of LEO cell 230 relative to UE 210 is greater than the velocity of GEO cell 220, LEO cell 230 may be more affected by doppler shift than GEO cell 220. Accordingly, when performing a handover from the GEO cell 220 to the LEO cell 230 without considering the influence of the doppler shift, the reception performance of the UE 210 may be deteriorated.

Fig. 3 is a diagram illustrating LEO unit environments of different altitudes according to an embodiment.

In fig. 3, a description repeated with the descriptions of fig. 1 and 2 may be omitted. Referring to fig. 3, a ue 310 may access a network of a wireless communication system by transmitting and receiving signals using a first LEO cell (LEO 1) 320 or a second LEO cell (LEO 2) 330 having different altitudes.

Because the second LEO cell 330 may orbit at a lower elevation than the first LEO cell 320, the RSRP value of the second LEO cell 330 measured by the UE 310 may be greater than the RSRP value of the first LEO cell 320. However, because the velocity of the second LEO cell 330 relative to the UE 310 may be greater than the velocity of the first LEO cell 320, the second LEO cell 330 may be more affected by doppler shift than the first LEO cell 320. That is, when handover from the first LEO cell 320 to the second LEO cell 330 is performed only with respect to RSRP, the reception performance of the UE 310 may be deteriorated.

Fig. 4 is a block diagram illustrating a UE according to an embodiment.

Referring to fig. 4, a ue 400 may include a plurality of antennas AT, a Radio Frequency (RF) Integrated Circuit (IC) 410, a baseband IC 420, a processor 430, and a memory 440. Note that in other embodiments, the implementation example of the UE 400 shown in fig. 4 may be modified to include more or fewer components.

The RFIC 410 may perform functions of transmitting and receiving signals over a wireless channel using a plurality of antennas AT, such as frequency band conversion and amplification of signals. Specifically, the RFIC 410 may up-convert a baseband signal provided from the baseband IC 420 into an RF band signal, then transmit the RF band signal through the antenna AT, and down-convert the RF band signal received through the antenna AT into a baseband signal. For example, the RFIC 410 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like. The RFIC 410 may adjust the phase and amplitude of each signal transmitted and received through the antenna AT for beamforming. Further, the RFIC 410 may perform Multiple Input Multiple Output (MIMO), and may receive multiple layers when performing MIMO operations.

The baseband IC 420 may perform conversion operations between baseband signals and bit streams according to the physical layer standard of the system. For example, baseband IC 420 may generate complex symbols by encoding and modulating a transmission bit stream during data transmission. Further, the baseband IC 420 may reconstruct the received bit stream by demodulating and decoding the baseband signal provided from the RFIC 410 during data reception.

The RFIC 410 and baseband IC 420 may transmit and receive signals as described above. Each of the RFIC 410 and the baseband IC 420 may be referred to as a transmitter, receiver, transceiver, or communicator. Further, at least one of the RFIC 410 and the baseband IC 420 may include a plurality of communication modules that support a plurality of different radio access technologies. Further, at least one of the RFIC 410 and the baseband IC 420 may include different communication modules to process signals of different frequency bands. For example, the different radio access technologies may include New Radio (NR) technologies, LTE technologies, and so on. Further, the different frequency bands may include an ultra-high frequency band, a millimeter wave frequency band, and the like. UE 400 may communicate with a cell using RFIC 410 and baseband IC 420.

The processor 430 may control the overall operation of the UE 400. In an embodiment, the processor 430 may include a measurement/reporting circuit 431. To perform handover and/or for other communication operations, the UE 400 may transmit user capability information (interchangeably, "user capability") including the reception performance information 441 to the serving cell. The UE 400 may measure RSRP and Doppler Shift (interchangeably, "Doppler Shift") of the reference signal with reference to Radio Resource Control (RRC) configuration information received from the serving cell. Further, UE 400 may receive "doppler parameters" from the serving cell. The Doppler parameters may be used in combination with measured RSRP and Doppler shift to calculate "rsrp_doppler values" (interchangeably, only "rsrp_doppler") from RRC configuration information. The rsrp_doppler value is a signal metric reported to the serving cell where it is used to determine whether a handover should occur. By reporting rsrp_doppler to the serving cell, the UE 400 may reduce feedback overhead compared to reporting RSRP and Doppler shift alone.

In some embodiments, the RRC configuration information may be configured according to standards defined in NR 3gpp TS 38.331. For example, RRC configuration information for measuring RSRP and doppler shift of the reference signal may be set as shown in table 1 below. The parameter rsrp-doppler may be reported periodically or aperiodically with reference to ReportConfigNR, which indicates the reporting type in table 1. However, in contrast to embodiments of the present disclosure, the parameter may not depend on user capabilities and/or Doppler parameters. In embodiments of the present disclosure, RSRP-Doppler may be replaced by rsrp_doppler. Further, in embodiments herein, measreportquality indicating the measurement quantity to report may include rsrp_doppler. Further, in embodiments herein, the NR-RS-Type indicating the Type of reference signal to be measured may include a Synchronization Signal Block (SSB), a channel state information-reference signal (CSI-RS), and a Tracking Reference Signal (TRS) and/or a physical downlink shared channel demodulation reference signal (PDSCH-DMRS) having a relatively short period.

TABLE 1

Table 2 indicates RRC configurations for generating measurement events. In particular, table 2 may indicate an RRC configuration for generating a measurement event when the report type of table 1 is eventTriggered. In the examples herein, RSRP-Doppler may be replaced by rsrp_doppler in table 2.

TABLE 2

According to the present embodiment, table 3 may indicate RRC configuration of UE 400 to measure and report a level 3 (L3) value. More specifically, fi lterconfig, which represents the filter coefficients for L3 measurement, may include Fi lterCoefficientRSRP _doppler.

TABLE 3

Table 4 may indicate RRC configuration of UE 400 to measure and report a level 1 (L1) value. When cri-RSRP-Doppler and ssb-Index-RSRP-Doppler are set to 1, in this embodiment, UE 400 may report rsrp_doppler to the serving cell using CSI.

TABLE 4

Table 5 may list RRC configurations indicating measurements reported by the UE 400. According to the present embodiment, the measurement values reported by the UE 400 may include rsrp_doppler. (RSRP_Doppler may replace RSRP-Doppler in this embodiment.)

TABLE 5

The Doppler parameter may be defined as a parameter for calculating rsrp_doppler. As previously described, rsrp_doppler is a value that considers both RSRP and Doppler shift.

In some embodiments, the doppler parameter may refer to an offset coefficient α, where α is a real number greater than zero. In this regard, rsrp_doppler may be calculated as in equation 1 below. As shown in equation 1, rsrp_doppler may have a value that varies according to the value of Doppler Shift (doppler_shift) measured by the UE 400.

< equation 1>

RSRP _{_} Doppler＝RSRP-α*Doppler_shift

In another embodiment, the Doppler parameter is a parameter referred to herein as "Delta_Dopple" (or "Delta Doppler"), which may be one of a plurality of values corresponding to different ranges of Doppler frequency shifts. For this, rsrp_doppler can be calculated according to the following equation 2. As shown in equation 2 and fig. 8A and 8B, rsrp_doppler and delta_doppler may each have a value that varies according to the range of Doppler shift measured by the UE 400.

< equation 2>

RSRP _{_} Doppler＝RSRP-Delta_Doppler

The memory 440 may store data such as basic programs, application programs, and setting information for the operation of the UE 400. Further, according to an embodiment, the memory 440 may store a program executed when the processor 430 performs operations related to measurement and reporting in the form of a code. In an embodiment, the memory 440 may store reception performance information 441 of the UE 400 for determining the doppler parameter value.

The reception performance information 441 of the UE 400 may indicate the capability of the UE 400 to perform frequency and time synchronization with the serving cell. For example, the reception performance information 441 of the UE 400 may indicate the reception performance capability of the first level or the second level higher. A UE having the second level of reception performance information 441 may mean that the UE has better frequency and time synchronization capability than a UE having the first level of reception performance information 441. Additional levels may be defined and applied.

UE 400 may provide reception performance information 441 to the serving cell. The serving cell may set the doppler parameter value based on the reception performance information 441. For example, when the reception performance information 441 of the UE 400 indicates the reception performance of the second level, the doppler parameter may be set to a low value. On the other hand, when the reception performance information 441 of the UE 400 indicates the reception performance of the first level, the doppler parameter may be set to a higher value.

Referring to equation 1 above, the offset coefficient α when the reception performance information 441 of the UE 400 is the second level may be set to be smaller than the offset coefficient α when the reception performance information 441 of the UE 400 is the first level. The smaller the offset coefficient α, the greater the influence of RSRP on rsrp_doppler and the smaller the influence of Doppler offset on rsrp_doppler. That is, when the reception performance information 441 of the UE 400 is of the second level, the frequency and time synchronization capability of the UE 400 is high, and thus, in rsrp_doppler, the influence of Doppler shift can be considered to be small and the influence of RSRP can be considered to be large. Equation 1 has been described as an example, but in addition, in the case of equation 2, when the reception performance information 441 of the UE 400 is of the second level, delta doppler may be set to be smaller than that when the reception performance information 441 of the UE 400 is of the first level.

Fig. 5 is a diagram of a signal exchange between a UE and a serving cell according to an embodiment. Fig. 5 may be described with reference to fig. 1 to 4 described above.

In operation S110, the UE 510 may transmit reception performance information of the UE 510 to the serving cell 520. To this end, the UE 510 may transmit user capabilities including reception performance information to the serving cell 520.

In operation S120, the UE 510 may receive doppler parameters and RRC configuration information from the serving cell 520. Here, the doppler parameter may have a value generated based on reception performance information of the UE or user capability including the reception performance information. In some embodiments, the doppler parameter is provided to the UE as an offset coefficient α, as shown in equation 1. In another embodiment, the Doppler parameters are provided to the UE 510 as Delta Doppler, for example in the form of a table corresponding to equation 2 and as shown in FIGS. 8A and 8B.

In operation S130, the UE 510 may measure RSRP and doppler shift of the reference signal with reference to RRC configuration information received from the serving cell 520. Further, the UE 510 may calculate rsrp_doppler based on the measured RSRP, the measured Doppler shift, and the Doppler parameter α or Delta Doppler based on equation (1) or equation (2).

In operation S140, the UE 510 may report the rsrp_doppler calculated in operation S130 to the serving cell 520. In some embodiments, UE 510 may report rsrp_doppler as an L1 value using CSI. In another embodiment, the UE 510 may report rsrp_doppler as an L3 value using RRC measurement reporting.

In operation S150, the serving cell 520 may determine whether to perform handover of the UE 510 considering rsrp_doppler received from the UE 510. For example, if rsrp_doppler for the serving cell is below a first predetermined threshold and rsrp_doppler for the neighboring cell is above a second predetermined threshold, a handoff process may be initiated. When the handover process is initiated, both the serving cell 520 and the UE 510 may cooperate to perform conventional handover operations with respect to the target cell.

Fig. 6 is a flowchart illustrating RSRP and doppler shift measurement operations according to an embodiment. The operation of fig. 6 may be an example of a portion of operation S130 of fig. 5.

In operation S131, the UE 510 may identify the type of the reference signal included in the RRC configuration information. In some embodiments, the reference signal may be SSB, CSI-RS, TRS, or the like.

In another embodiment, the reference signal may be a signal having a shorter period than the SSB or CSI-RS, e.g., TRS, PDSCH, DMRS, etc. When the serving cell 520 is an LEO cell, measuring a reference signal having a short period may improve measurement accuracy because doppler shift of a signal transmitted/received between the UE 510 and the serving cell 520 is large.

In operation S132, the UE 510 may measure RSRP and doppler shift of the reference signal. For example, when the reference signal included in the RRC configuration information is a TRS, the UE 510 may measure RSRP and doppler shift of the TRS.

Fig. 7 is a flowchart illustrating an rsrp_doppler reporting operation according to an embodiment. The operation of fig. 7 may correspond to the embodiment of operation S140 of fig. 5.

In operation S141, the UE 510 may determine whether a report triggering criterion is satisfied. Here, the reporting triggering criteria may mean a specific condition that causes the UE 510 to report rsrp_doppler to the serving cell 520. For example, the report triggering criteria may be satisfied when rsrp_doppler (with respect to the neighboring cell) calculated in operation S130 of fig. 5 is equal to or greater than a predetermined threshold. When the report trigger criteria is satisfied, the UE 510 may perform operation S142. On the other hand, when the report trigger criteria is not satisfied, the UE 510 may repeatedly perform operation S141.

In operation S142, the UE 510 may report rsrp_doppler to the serving cell 520. In some embodiments, operation S142 may be an L1 reporting operation using CSI. In another embodiment, operation S142 may be an L3 reporting operation using RRC measurement reporting.

Fig. 8A and 8B are tables showing examples of Delta doppler according to doppler shift.

Fig. 8A and 8B may represent the relationship between the doppler shift and Delta doppler of equation 2 above. Fig. 8A may correspond to a case where the reception performance information of the UE is of a first level, and fig. 8B may correspond to a case where the reception performance information of the UE is of a second level. For example, the predetermined range of doppler shifts corresponds to different respective values of Delta doppler, wherein the range may be different for different reception performance levels. For example, when the UE measured doppler shift is 15Hz (in the range of 10 to 20 Hz), the first level UE may set the Delta doppler value to 2. On the other hand, when the UE measured doppler shift is 15Hz, the UE of the second level may set the Delta doppler value to 1. Referring to equation 2 above, a UE of a first class having lower reception performance than a UE of a second class may set a larger Delta doppler value to more exacerbate the effect of doppler shift.

Fig. 9 is a block diagram illustrating a wireless communication system according to an embodiment.

For example, the wireless communications apparatus 1100 of fig. 9 can be applied to a UE (e.g., 110 of fig. 1) implemented in accordance with some embodiments. Further, in some embodiments, the wireless communications apparatus 1100 of fig. 9 can operate in a Standalone (SA) mode or a non-standalone (NSA) mode.

As an example, a wireless communications apparatus 1100 implemented in a network environment 1000 is illustrated in fig. 9.

The wireless communication device 1100 may include a bus 1140, a processor 1110, a memory 1120, an input/output interface 1150, a display module 1160, and a communication interface 1170. The wireless communication device 1100 may omit at least one of the components or additionally include at least one other component. However, for ease of description, in an embodiment, the wireless communication apparatus 1100 including components will be described as an example.

Bus 1140 may connect processor 1110, memory 1120, input/output interface 1150, display module 1160, and communication interface 1170 to each other. Accordingly, exchange and transfer of signals (e.g., control messages and/or data) between processor 1110, memory 1120, input/output interface 1150, display module 1160, and communication interface 1170 may be performed via bus 1140.

The processor 1110 may include one or more of a Central Processing Unit (CPU), an Application Processor (AP), and a Communication Processor (CP). In addition, the processor 1110 may perform operations or data processing related to, for example, control and/or communication of other components in the wireless communication device 1100. For reference, the processor 1110 may have a configuration including the functions of the measurement/reporting circuit 431 of fig. 4.

Memory 1120 may include volatile memory and/or nonvolatile memory. In addition, the memory 1120 may store commands or instructions or data related to other components in the wireless communication device 1100, for example.

Further, memory 1120 may store software and/or programs 1130. Programs 1130 may include, for example, a kernel 1135, middleware 1134, application Programming Interfaces (APIs) 1133, application programs 1132 (also referred to as "applications"), network access information 1131, and the like.

For reference, at least some of the kernel 1135, middleware 1134, and APIs 1133 may be referred to as an Operating System (OS). In addition, the memory 1120 may be a configuration including the functions of the memory 440 of fig. 4.

The input/output interface 1150 may transmit commands or instructions or data, for example, input from a user or another external device to other components of the wireless communication device 1100. In addition, the input/output interface 1150 may output commands or instructions or data received from other components of the wireless communication device 1100 to a user or other external device.

The display module 1160 may comprise, for example, a Liquid Crystal Display (LCD), a Light Emitting Diode (LED) display, an Organic Light Emitting Diode (OLED) display, a microelectromechanical system (MEMS) display, or an electronic paper display.

In addition, the display module 1160 may display various content (e.g., text, images, video, icons, or symbols) to a user, for example. In addition, the display module 1160 may include a touch screen and may receive, for example, touch, gesture, proximity touch, or hover input through the use of an electronic pen or a portion of the user's body.

Communication interface 1170 may establish communication between wireless communication device 1100 and external devices, such as electronic devices 1200 and 1300 or server 1500. For example, the communication interface 1170 may be connected to the network 1400 by wireless communication or wired communication to communicate with an external device (e.g., the electronic device 1300 or the server 1500). In addition, the communication interface 1170 may communicate with external devices (e.g., the electronic device 1200) via wireless communication.

In addition, the network 1400 may be a telecommunications network and may include, for example, at least one of a computer network (e.g., LAN or WAN), the internet, and a telephone network.

Meanwhile, each of the external electronic devices 1200 and 1300 may be the same type as the wireless communication device 1100 or a different type. In addition, server 1500 may include a group of one or more servers.

For reference, all or some of the operations performed by the wireless communication device 1100 may be performed by other external devices (e.g., the electronic devices 1200 and 1300 or the server 1500).

In addition, when the wireless communication device 1100 needs to perform a function or service automatically or upon request, the wireless communication device 1100 itself may perform the function or service, or some functions or services may be requested from an external device (e.g., the electronic devices 1200 and 1300 or the server 1500). In addition, other external devices (e.g., electronic devices 1200 and 1300 or server 1500) may perform the requested function or service and transmit the execution result to the wireless communication device 1100. In this case, the wireless communication apparatus 1100 may perform a function or service by processing the received result as it is or additionally.

For such mechanisms, for example, cloud computing, distributed computing, or client-server computing techniques may be applied to the wireless communication device 1100.

As described above, in various embodiments of the inventive concept, by reporting the rsrp_doppler value to the serving cell, feedback overhead may be reduced compared to the case of reporting RSRP and Doppler shift, respectively. In addition, the network environment may determine whether to perform handover considering rsrp_doppler in which RSRP and Doppler bias are reflected.

While the present inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.

Claims (20)

1. A method of operation of a user device, the method of operation comprising:

transmitting user capability including reception performance information of the user equipment to a serving cell;

receiving doppler parameters generated based on the user capabilities and radio resource control configuration information from the serving cell;

measuring a reference signal received power and a doppler shift of a reference signal with reference to the radio resource control configuration information; and

reporting an rsrp_doppler value to the serving cell, the rsrp_doppler value being a signal metric calculated based on the measured reference signal received power, the measured Doppler shift, and the Doppler parameter.

2. The method of operation of claim 1, wherein the Doppler parameter comprises an offset coefficient a and the rsrp_doppler value is calculated according to:

RSRP _{_} Doppler＝RSRP-α*Doppler_shift。

3. the method of operation of claim 1, wherein,

the Doppler parameter includes a "Delta_Doppler" parameter having one of a plurality of values corresponding to respective different ranges of Doppler frequency shift, an

The rsrp_doppler value is calculated according to the following equation:

RSRP _{_} Doppler＝RSRP-Delta_Doppler。

4. the method of operation of claim 1, wherein the radio resource control configuration information comprises information regarding aperiodic reporting of the rsrp_doppler value.

5. The method of operation of claim 1, wherein the reference signal comprises at least one of a tracking reference signal and a physical downlink shared channel demodulation reference signal.

6. The method of operation of claim 1, wherein,

the radio resource control configuration information includes channel state information-reference signals, and

the reporting the rsrp_doppler value to the serving cell includes: reporting the rsrp_doppler value to the serving cell by using channel state information generated based on the channel state information-reference signal.

7. The method of operation of claim 1, wherein

The radio resource control configuration information includes L3 filter coefficients, and

the reporting the rsrp_doppler value to the serving cell includes: reporting the rsrp_doppler value generated by applying the L3 filter coefficients to the serving cell.

8. The method of operation of claim 1, wherein reporting of the rsrp_doppler value occurs when the user equipment detects a measurement event.

9. A user equipment, comprising:

a memory configured to store reception performance information of the user equipment; and

a processor configured to transmit a user capability including reception performance information of the user equipment to a serving cell, receive a Doppler parameter generated based on the user capability and radio resource control configuration information from the serving cell, measure a reference signal reception power and a Doppler shift of a reference signal with reference to the radio resource control configuration information, and report an rsrp_doppler value to the serving cell, the rsrp_doppler value being a signal metric calculated based on the measured reference signal reception power, the measured Doppler shift, and the Doppler parameter.

10. The user equipment of claim 9, wherein the radio resource control configuration information comprises information regarding aperiodic reporting.

11. The user equipment of claim 9, wherein the reference signal comprises at least one of a tracking reference signal and a physical downlink shared channel demodulation reference signal.

12. The user equipment of claim 9, wherein

The radio resource control configuration information includes channel state information-reference signals, and

the processor is configured to report the rsrp_doppler value to the serving cell by using channel state information generated based on the channel state information-reference signal.

13. The user equipment of claim 9, wherein

The radio resource control configuration information includes L3 filter coefficients, and

the processor is configured to report the rsrp_doppler value generated by applying the L3 filter coefficients to the result of the measurement to the serving cell.

14. The user equipment of claim 9, wherein the processor is configured to report the rsrp_doppler value to the serving cell when the user equipment detects a measurement event.

15. A wireless communication system, comprising:

a serving cell configured to send doppler parameters generated based on user capabilities and radio resource control configuration information to a user equipment; and

the user equipment is configured to measure a reference signal received power and a Doppler shift of a reference signal with reference to the radio resource control configuration information, and report an rsrp_doppler value to the serving cell, the rsrp_doppler value being a signal metric calculated based on the measured reference signal received power, the measured Doppler shift, and the Doppler parameter.

16. The wireless communication system of claim 15, wherein the serving cell is a near-earth orbit cell.

17. The wireless communication system of claim 15, wherein the user equipment is configured to report the rsrp_doppler value to the serving cell when the rsrp_doppler value is equal to or greater than a threshold level.

18. The wireless communication system of claim 15, wherein

The Doppler parameter includes a shift coefficient alpha, an

The rsrp_doppler value is calculated according to the following equation:

RSRP _{_} Doppler＝RSRP-α*Doppler_shift。

19. the wireless communication system of claim 15, wherein

The Doppler parameter includes a "Delta_Doppler" parameter having one of a plurality of values corresponding to respective different ranges of the Doppler shift, an

The rsrp_doppler value is calculated according to the following equation:

RSRP _{_} Doppler＝RSRP-Delta_Doppler。

20. the wireless communication system of claim 19, wherein the serving cell and the user equipment are configured to: a handover to the target cell is cooperatively performed when the rsrp_doppler value for the serving cell is below a first predetermined threshold and the rsrp_doppler value for a neighboring cell is above a second predetermined threshold.