KR101944926B1 - A method and apparatus for compensating frequency offset in a wireless communication system - Google Patents

Abstract

A method and apparatus for compensating for frequency offset in a wireless communication system are disclosed. Specifically, the method includes estimating a frequency offset based on a signal received from a base station, generating an oscillation frequency of the terminal by reflecting the estimated frequency offset according to a frequency offset compensation period, Determining whether or not an event triggering a change of the frequency offset compensation period is detected; and changing the frequency offset compensation period when the event is detected. have.

Description

Field of the Invention [0001] The present invention relates to a method and apparatus for compensating for frequency offset in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a method for compensating a frequency offset between a base station and a terminal and an apparatus for supporting the same.

The mobile communication system has been developed to provide voice service while ensuring the user 's activity. However, in the mobile communication system, not only the voice but also the data service are extended. At present, due to the increase of the explosive traffic, there is a shortage of resources and users require higher speed service, have.

The requirements of the next-generation mobile communication system largely depend on the acceptance of explosive data traffic, the dramatic increase in the rate per user, the acceptance of a significantly increased number of connected devices, very low end-to-end latency, Should be able to. For this purpose, a dual connectivity, a massive multiple input multiple output (MIMO), an in-band full duplex, a non-orthogonal multiple access (NOMA) wideband support, and device networking.

There arises a problem of deterioration of reception performance due to frequency offset between the base station and the terminal when the terminal rapidly consumes current or power.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for compensating for a frequency offset by predicting an event that abruptly increases consumption current or power consumption in a terminal in a wireless communication system.

In addition, the present invention proposes a method for compensating a frequency offset by using a message on a communication protocol for an event that abruptly increases consumption current or consumed power in a terminal.

In addition, the present invention proposes a method for compensating a frequency offset by measuring a current or power consumed in a terminal through a hardware configuration or a software configuration.

In addition, the present invention proposes a method for changing an update period of a frequency signal for compensating for a frequency offset by predicting an event that abruptly increases consumption current or consumed power in a terminal.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

A method for compensating for a frequency offset in a wireless communication system in an embodiment of the present invention includes estimating a frequency offset based on a signal received from a base station, Generating an oscillation frequency of the UE by reflecting the estimated frequency offset according to a frequency offset compensation period; generating an event triggering a change of the frequency offset compensation period; ), And changing the frequency offset compensation period when the event is detected.

In addition, in the method, the step of estimating the frequency offset based on the received signal from the base station may include calculating a signal-to-noise ratio (SNR) value of the received signal, And estimating the frequency offset when the calculated SNR value is greater than a preset threshold value.

The method may further include the step of maintaining the frequency offset compensation period when the event is not detected.

Also, in the method, the step of checking whether or not the event is detected may include the step of identifying the event using a preset event list, And information about a message on at least one communication protocol associated with at least one event that triggers a change.

In the method, the detecting the event using the preset event list may include receiving a message on the at least one communication protocol from the base station.

According to another aspect of the present invention, the step of changing the frequency offset compensation period comprises the steps of: accumulating the estimated frequency offset based on the reduced accumulation ratio; and calculating the frequency offset compensation period based on the accumulated frequency offset. .

In addition, in the method, the step of changing the frequency offset compensation period may include calculating at least one value of a current consumption current or a current consumption power of the terminal, and using at least one calculated value, Calculating a deviation value with respect to a current or consumed power; and changing the frequency offset compensation period when the calculated deviation value is greater than a predetermined threshold value.

The method may further include storing information on a message on a communication protocol related to a currently generated event in the event list if the event is not detected.

The method may further include the step of maintaining the frequency offset compensation period when the event is not detected and the calculated deviation value is less than or equal to a predetermined threshold value.

In the method, if the calculated deviation value is less than or equal to a predetermined threshold value, information on a message on a communication protocol related to the event is deleted from the event list. And the like.

The method may further include the step of maintaining the frequency offset compensation period when the calculated SNR value is less than or equal to a preset threshold value.

In addition, in a wireless communication system according to another embodiment of the present invention, a terminal that compensates for a frequency offset may include a transceiver for transmitting and receiving a radio signal and a processor functionally connected to the transceiver .

Here, the processor estimates a frequency offset based on a signal received from the base station, and calculates an oscillation frequency of the terminal based on the estimated frequency offset according to a frequency offset compensation period, And to check whether or not an event triggering the change of the frequency offset compensation period is detected and to change the frequency offset compensation period when the event is detected.

According to the embodiment of the present invention, in the case where the consumed current or the consumed power at the terminal suddenly increases, the frequency offset between the base station and the terminal can be efficiently compensated.

The effects obtained in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description .

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the technical features of the invention.
1 shows a structure of a radio frame in a wireless communication system to which the present invention can be applied.
2 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which the present invention can be applied.
3 illustrates a structure of a downlink subframe in a wireless communication system to which the present invention can be applied.
FIG. 4 illustrates a structure of a UL subframe in a wireless communication system to which the present invention can be applied.
5 shows an example of an apparatus for compensating for frequency offset according to various embodiments of the present invention.
6 illustrates an apparatus for compensating for frequency offset in accordance with an embodiment of the present invention.
7 is a flowchart illustrating an operation of a UE for compensating a frequency offset according to an embodiment of the present invention.
8 illustrates an apparatus for compensating for frequency offset according to another embodiment of the present invention.
9 is a flowchart illustrating an operation of a UE for compensating for a frequency offset according to another embodiment of the present invention.
10 illustrates an apparatus for compensating for frequency offset in accordance with another embodiment of the present invention.
11 is a flowchart illustrating an operation of a UE that compensates for a frequency offset according to another embodiment of the present invention.
12 shows an operation flowchart of a UE for correcting a frequency offset according to various embodiments of the present invention.
13A and 13B show graphs of quality and frequency for signals received at a terminal in accordance with various embodiments of the present invention.
14 illustrates a block diagram of a wireless communication apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention.

In this specification, a base station has a meaning as a terminal node of a network that directly communicates with a terminal. The specific operation described herein as performed by the base station may be performed by an upper node of the base station, as the case may be. That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an evolved NodeB (eNB), a base transceiver system (BTS), an access point (AP) . Also, a 'terminal' may be fixed or mobile and may be a mobile station (UE), a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS) Advanced Mobile Station (WT), Wireless Terminal (WT), Machine-Type Communication (MTC), Machine-to-Machine (M2M), and Device-to-Device (D2D) devices.

Hereinafter, a downlink (DL) means communication from a base station to a terminal, and an uplink (UL) means communication from a terminal to a base station. In the downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In the uplink, the transmitter may be part of the terminal and the receiver may be part of the base station.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

The following techniques may be used in various wireless communication systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC- (non-orthogonal multiple access), and the like. CDMA can be implemented with radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA can be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented with wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and evolved UTRA (E-UTRA). UTRA is part of the universal mobile telecommunications system (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (evolved UMTS) using E-UTRA, adopting OFDMA in downlink and SC-FDMA in uplink. LTE-A (advanced) is the evolution of 3GPP LTE.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, the steps or portions of the embodiments of the present invention which are not described in order to clearly illustrate the technical idea of the present invention can be supported by the documents. In addition, all terms disclosed in this document may be described by the standard document.

For clarity of description, 3GPP LTE / LTE-A is mainly described, but the technical features of the present invention are not limited thereto.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention.

In this specification, a base station has a meaning as a terminal node of a network that directly communicates with a terminal. The specific operation described herein as performed by the base station may be performed by an upper node of the base station, as the case may be. That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an evolved NodeB (eNB), a base transceiver system (BTS), an access point (AP) . Also, a 'terminal' may be fixed or mobile and may be a mobile station (UE), a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS) Advanced Mobile Station (WT), Wireless Terminal (WT), Machine-Type Communication (MTC), Machine-to-Machine (M2M), and Device-to-Device (D2D) devices.

Hereinafter, a downlink (DL) means communication from a base station to a terminal, and an uplink (UL) means communication from a terminal to a base station. In the downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In the uplink, the transmitter may be part of the terminal and the receiver may be part of the base station.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

The following techniques may be used in various wireless communication systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC- (non-orthogonal multiple access), and the like. CDMA can be implemented with radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA can be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented with wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and evolved UTRA (E-UTRA). UTRA is part of the universal mobile telecommunications system (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (evolved UMTS) using E-UTRA, adopting OFDMA in downlink and SC-FDMA in uplink. LTE-A (advanced) is the evolution of 3GPP LTE.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, the steps or portions of the embodiments of the present invention that are not described in order to clearly illustrate the technical idea of the present invention can be supported by the documents. In addition, all terms disclosed in this document may be described by the standard document.

For clarity of description, 3GPP LTE / LTE-A is mainly described, but the technical features of the present invention are not limited thereto.

System General

1 shows a structure of a radio frame in a wireless communication system to which the present invention can be applied.

3GPP LTE / LTE-A supports a Type 1 radio frame structure applicable to Frequency Division Duplex (FDD) and a Type 2 radio frame structure applicable to TDD (Time Division Duplex).

In FIG. 1, the size of the radio frame in the time domain is represented by a multiple of a time unit of T_s = 1 / (15000 * 2048). The downlink and uplink transmissions are composed of radio frames having intervals of T_f = 307200 * T_s = 10ms.

1 (a) illustrates the structure of a Type 1 radio frame. Type 1 radio frames can be applied to both full duplex and half duplex FDD.

A radio frame is composed of 10 subframes. One radio frame is composed of 20 slots having a length of T_slot = 15360 * T_s = 0.5 ms, and each slot is given an index from 0 to 19. One subframe consists of two consecutive slots in the time domain, and the subframe i consists of slots 2i and 2i + 1. The time taken to transmit one subframe is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms and the length of one slot may be 0.5 ms.

In the FDD, the uplink transmission and the downlink transmission are classified in the frequency domain. While there is no limit to full-duplex FDD, terminals can not transmit and receive simultaneously in half-duplex FDD operation.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain, and includes a plurality of resource blocks (RBs) in the frequency domain. Since 3GPP LTE uses OFDMA in the downlink, an OFDM symbol is intended to represent one symbol period. The OFDM symbol may be one SC-FDMA symbol or a symbol interval. A resource block is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot.

1 (b) shows a type 2 frame structure (frame structure type 2).

The Type 2 radio frame is composed of two half frames each having a length of 153600 * T_s = 5 ms. Each half frame consists of 5 subframes with a length of 30720 * T_s = 1 ms.

In the Type 2 frame structure of the TDD system, the uplink-downlink configuration is a rule indicating whether the uplink and the downlink are allocated (or reserved) for all the subframes.

Table 1 shows an uplink-downlink configuration.

Referring to Table 1, 'D' denotes a subframe for downlink transmission, 'U' denotes a subframe for uplink transmission, 'S' denotes a downlink pilot (DwPTS) A special subframe consisting of three fields: a time slot, a guard interval (GP), and an uplink pilot time slot (UpPTS).

The DwPTS is used for initial cell search, synchronization, or channel estimation in the UE. UpPTS is used to synchronize the channel estimation at the base station and the uplink transmission synchronization of the UE. GP is a period for eliminating the interference caused in the uplink due to the multi-path delay of the downlink signal between the uplink and the downlink.

Each subframe i is composed of a slot 2i and a slot 2i + 1 each having a length of T_slot = 15360 * T_s = 0.5 ms.

The uplink-downlink structure can be classified into seven types, and the positions and / or the numbers of the downlink subframe, the special subframe, and the uplink subframe are different for each structure.

The point of time when the downlink is changed to the uplink or the time when the uplink is switched to the downlink is referred to as a switching point. Switch-point periodicity refers to a period in which the uplink subframe and the downlink subframe are switched in the same manner, and both 5ms or 10ms are supported. The special sub-frame S exists for each half-frame when a 5-ms downlink-uplink switching point has a period, and exists only in the first half-frame when a 5-ms downlink-uplink switching point has a period.

In all configurations, the 0th and 5th subframes and the DwPTS are only for downlink transmission. UpPTS and subframes immediately following a subframe subframe are always intervals for uplink transmission.

The uplink-downlink configuration is system information, and both the base station and the terminal can know it. The base station can inform the terminal of the change of the uplink-downlink allocation state of the radio frame by transmitting only the index of the configuration information every time the uplink-downlink configuration information is changed. In addition, the configuration information may be transmitted as a kind of downlink control information through a physical downlink control channel (PDCCH) like other scheduling information, and may be transmitted to all terminals in a cell through a broadcast channel as broadcast information .

Table 2 shows the configuration (DwPTS / GP / UpPTS length) of the special subframe.

The structure of the radio frame according to the example of FIG. 1 is only one example, and the number of subcarriers included in a radio frame, the number of slots included in a subframe, and the number of OFDM symbols included in a slot are changed variously .

2 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which the present invention can be applied.

Referring to FIG. 2, one downlink slot includes a plurality of OFDM symbols in a time domain. Herein, one downlink slot includes 7 OFDM symbols, and one resource block includes 12 subcarriers in the frequency domain. However, the present invention is not limited thereto.

Each element on the resource grid is a resource element, and one resource block (RB) contains 12 × 7 resource elements. The number of resource blocks N DL included in the downlink slot is dependent on the downlink transmission bandwidth.

The structure of the uplink slot may be the same as the structure of the downlink slot.

3 illustrates a structure of a downlink subframe in a wireless communication system to which the present invention can be applied.

3, a maximum of three OFDM symbols preceding a first slot in a subframe is a control region in which control channels are allocated, and the remaining OFDM symbols are allocated to a data region (PDSCH) to which a Physical Downlink Shared Channel data region). Examples of the downlink control channel used in the 3GPP LTE include a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), and a Physical Hybrid-ARQ Indicator Channel (PHICH).

The PCFICH is carried in the first OFDM symbol of the subframe and carries information about the number of OFDM symbols (i.e., the size of the control region) used for transmission of control channels in the subframe. The PHICH is a response channel for the uplink and carries an ACK (Acknowledgment) / NACK (Not-Acknowledgment) signal for HARQ (Hybrid Automatic Repeat Request). The control information transmitted through the PDCCH is referred to as downlink control information (DCI). The downlink control information includes uplink resource allocation information, downlink resource allocation information, or an uplink transmission (Tx) power control command for an arbitrary terminal group.

PDCCH includes resource allocation and transmission format (also referred to as downlink grant) of DL-SCH (Downlink Shared Channel), resource allocation information of UL-SCH (also referred to as uplink grant), PCH Resource allocation for an upper-layer control message such as paging information in a paging channel, system information in a DL-SCH, and a random access response transmitted on a PDSCH, A set of transmission power control commands for individual terminals in the group, and activation of VoIP (Voice over IP). The plurality of PDCCHs can be transmitted in the control domain, and the UE can monitor a plurality of PDCCHs. The PDCCH consists of a set of one or a plurality of consecutive control channel elements (CCEs). The CCE is a logical allocation unit used to provide a coding rate according to the state of the radio channel to the PDCCH. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of bits of the available PDCCH are determined according to the association between the number of CCEs and the coding rate provided by the CCEs.

The base station determines the PDCCH format according to the DCI to be transmitted to the UE, and attaches a CRC (Cyclic Redundancy Check) to the control information. The CRC is masked with a unique identifier (called a Radio Network Temporary Identifier (RNTI)) according to the owner or use of the PDCCH. If the PDCCH is for a particular UE, the unique identifier of the UE, e.g., C-RNTI (Cell-RNTI), may be masked in the CRC. Or a PDCCH for a paging message, a paging indication identifier, e.g., a Paging-RNTI (P-RNTI), may be masked to the CRC. System information identifier, SI-RNTI (system information RNTI) can be masked in the CRC if it is a PDCCH for system information, more specifically a system information block (SIB). A random access-RNTI (RA-RNTI) may be masked in the CRC to indicate a random access response that is a response to the transmission of the UE's random access preamble.

The enhanced PDCCH (EPDCCH) carries UE-specific signaling. The EPDCCH is located in a physical resource block (PRB) that is set to be terminal specific. In other words, as described above, the PDCCH can be transmitted in up to three OFDM symbols in the first slot in a subframe, but the EPDCCH can be transmitted in a resource region other than the PDCCH. The time (i.e., symbol) at which the EPDCCH starts in the subframe can be set in the terminal via higher layer signaling (e.g., RRC signaling, etc.).

The EPDCCH is a resource allocation (DL) associated with DL-SCH related transport format, resource allocation and HARQ information, UL-SCH related transport format, resource allocation and HARQ information, SL-SCH (Sidelink Shared Channel) and PSCCH Information, and so on. Multiple EPDCCHs may be supported and the terminal may monitor the set of EPCCHs.

The EPDCCH may be transmitted using one or more successive advanced CCEs (ECCEs), and the number of ECCEs per EPDCCH may be determined for each EPDCCH format.

Each ECCE may be composed of a plurality of enhanced resource element groups (EREGs). EREG is used to define the mapping of ECCEs to REs. There are 16 EREGs per PRB pair. All REs are numbered from 0 to 15 in the order in which the frequency increases, except for the RE carrying the DMRS in each PRB pair.

The UE can monitor a plurality of EPDCCHs. For example, one or two EPDCCH sets may be set in one PRB pair in which the terminal monitors the EPDCCH transmission.

Different coding rates can be realized for the EPCCH by merging different numbers of ECCEs. The EPCCH may use localized transmission or distributed transmission, and thus the mapping of the ECCE to the RE in the PRB may vary.

FIG. 4 illustrates a structure of a UL subframe in a wireless communication system to which the present invention can be applied.

Referring to FIG. 4, the uplink subframe can be divided into a control region and a data region in the frequency domain. A PUCCH (Physical Uplink Control Channel) that carries the uplink control information is allocated to the control region. A data area is assigned a physical uplink shared channel (PUSCH) for carrying user data. To maintain a single carrier characteristic, one UE does not transmit PUCCH and PUSCH at the same time.

A resource block (RB) pair is allocated to a PUCCH for one UE in a subframe. RBs belonging to the RB pair occupy different subcarriers in each of the two slots. It is assumed that the RB pair assigned to the PUCCH is frequency hopped at the slot boundary.

As a wireless communication system develops, a service provider and / or a user of a terminal (or a service user) require a high data transmission rate and / or high throughput .

Accordingly, Multiple Carrier Aggregation, 4x4 Multiple Input Multiple Output (MIMO) and Wi-Fi (Wireless Fidelity) aggregation techniques have been introduced to achieve the required rate and / or throughput.

Further, in a next generation communication system (e.g., a 5G (Generation) communication system), technologies requiring a large number of operations in a very short unit time (e.g., 1 ms) are being considered.

However, at a point in time when the above-described technologies requiring a large number of operations or having a high complexity are activated, the terminal may abruptly consume current or power.

The present invention relates to hardware (HardWare, H / W) (e.g., a radio frequency integrated circuit (RFIC), a radio frequency integrated circuit (For example, Signal to Noise Ratio (SNR)) due to degradation of a baseband chip, a baseband chip, and the like, .

More specifically, the present invention proposes a method and apparatus for detecting the occurrence time of a frequency offset due to deterioration of H / W and compensating (or correcting) the detected frequency offset.

In wireless communication systems, due to their robust nature in multipath fading channel environments, Orthogonal Frequency Division Multiplexing (OFDM) systems (or schemes) are widely used.

However, in the OFDM system, in order to increase the efficiency of the frequency, the interval between subcarriers (subcarriers) may be set to a minimum value under the condition that orthogonality between subcarriers is satisfied.

In this case, since there is no gap margin for maintaining the orthogonality between the subcarriers, the orthogonality of the subcarriers can be destroyed by the frequency offset.

More specifically, the performance of the OFDM system can be changed according to the Doppler frequency generated by the movement of the transmitting / receiving end and / or the frequency offset generated by the oscillator of the transmitting / receiving end.

Therefore, in order to prevent deterioration of reception performance due to frequency offset and to establish a system of high reliability, a receiver estimates a frequency offset at a receiving end (or a terminal), compensates an estimated frequency offset )Needs to be.

5 shows an example of an apparatus for compensating for frequency offset according to various embodiments of the present invention. FIG. 5 is merely for convenience of description, and does not limit the scope of the present invention.

5, the terminal includes an RF unit 502, a baseband unit 504, and a crystal oscillator 506.

Here, the RF unit 502 is used to receive a radio signal from the base station. Thus, the RF unit 502 may be referred to as an RFIC, a communication module, or an RF module.

The baseband unit 504 may convert a high frequency signal received from the base station into a baseband signal or convert a baseband signal into a high frequency signal. Accordingly, the baseband unit 504 may be referred to as a baseband modem.

In addition, the baseband unit 504 can estimate a frequency offset (or estimate an estimated frequency offset) generated between the terminal and the base station. Here, the frequency offset may mean the difference between the frequency used in the base station and the frequency used in the terminal. To estimate the frequency offset, the baseband unit 504 may include a frequency offset estimation module.

In this case, the baseband unit 504 calculates an estimated frequency offset value (or estimated frequency offset value) from a reference sequence received from the base station by using an algorithm that estimates a frequency offset generated between the terminal and the base station can do.

Also, the baseband unit 504 can accumulate the estimated frequency offset values calculated for each processing unit in consideration of the reliability of the calculated frequency offset values. Here, the processing unit may mean a unit by which the baseband unit 504 performs an operation for correcting the frequency offset.

Here, baseband unit 504 may calculate the length (or accumulation length) at which the estimated frequency offset is accumulated. The baseband unit 504 may accumulate the estimated frequency offset according to the calculated accumulated length.

In this case, the baseband unit 504 may use a scheme of applying an accumulation window to the calculated estimated frequency offset. Alternatively, the baseband unit 504 may accumulate the estimated frequency offset by applying a scheme that takes into account the accumulation ratio with previously calculated values (e.g., a Loop filter).

In addition, the baseband unit 504 may calculate an update period to reflect the accumulated estimated frequency offset. Here, the update period may mean a frequency modification update period for correcting the frequency offset.

If the estimated frequency offset values are accumulated through the above procedure, the baseband unit 504 can convert the accumulated value to a value (e.g., a DAC (Digital to Analog Converter) level) capable of controlling the crystal oscillator 506 .

Accordingly, the baseband unit 504 can control to compensate for the frequency offset using a crystal oscillator.

The crystal oscillator 506 may be updated using the value converted by the baseband unit 504. The updated crystal oscillator 506 can oscillate (or generate a frequency signal) the changed frequency, and compensate (or correct) the frequency offset generated between the terminal and the base station.

Herein, the crystal oscillator 506 may mean a VCTCXO (Voltage Controlled Temperature Compensated Crystal Oscillator). In this case, the value set to update the VCTCXO may be 'VCTCXO control DAC (VCRCXO control DAC)'.

5, an increase in abrupt consumption current or power consumption may cause deterioration in the operation of the baseband unit 504 and the crystal oscillator 506 as well as the operation of PLL (Phase Locked Loop) and power included in the RF unit 502 ≪ / RTI > Here, the consumed current or consumed power may mean current or power consumed in the terminal (or RF unit, crystal oscillator, baseband unit, etc.).

In this case, since the apparatus shown in Fig. 5 can not predict a time point at which the consumed current or consumed power sharply increases, the frequency update period for compensating the frequency offset can not be variably applied. In other words, the apparatus described in Fig. 5 can not change the frequency update period in accordance with a sudden change in consumed current or consumed power.

Accordingly, even when an abrupt consumption current or an increase in power consumption occurs, the frequency is updated according to a previously set period, so that the terminal can not secure optimal reception performance in which the frequency offset is compensated from the viewpoint of SNR reception. Particularly, when a high order operation such as 64QAM (Quadrature Amplitude Modulation) or 256QAM is performed, deterioration of reception performance of the UE can be caused to a large extent.

In order to solve the above problems, the present invention proposes a method for predicting a change point in a system (or environment) in which a consumed current or a consumed power is abruptly changed and a cumulative length of an estimated frequency offset (or frequency estimation offset) And a method and an apparatus capable of optimizing an update period of a frequency value.

In order to compensate the frequency offset according to the change of the consumed current or the consumed power, the present invention provides a method of using a communication protocol message between a base station and a terminal, b) hardware for measuring consumption current or consumed power, A method of using a configuration or a software configuration (or a configuration loop), and c) a method of using a combination of the methods of a) and b).

Method for compensating for frequency offset using communication protocol messages

6 illustrates an apparatus for compensating for frequency offset in accordance with an embodiment of the present invention. Fig. 6 is merely for convenience of description and does not limit the scope of the present invention.

Referring to FIG. 6, RF unit 602, baseband unit 604, and crystal oscillator 606 are each similar (or corresponding) to RF unit 502, baseband unit 504, and crystal oscillator 506 described in FIG.

However, unlike the baseband unit 504 of FIG. 5, the baseband unit 604 of FIG. 6 may utilize a message (or communication protocol message) on the communication protocol 608 to determine the occurrence of abrupt consumption current or power consumption. have.

The communication protocol 608 includes a Radio Resource Control (RRC) protocol, a Packet Data Convergence Protocol (PDCP), a Radio Link Control (RLC) protocol, a Medium Access Control, MAC) protocol, and a physical layer (PHY) protocol.

In this case, the baseband unit 604 may include a scheduling module that manages the scheduling of the UE.

In addition, to utilize the communication protocol message, the baseband unit 604 may utilize the event list 610. Here, the event list 610 may be referred to as a triggering event list. The event list 610 includes message event items (a first event, a second event, a third event, and a nth event) that cause a sudden change in consumption current or power consumption on the communication protocol 608.

Accordingly, the baseband unit 604 can predict that the consumed current or consumed power will change drastically as a message corresponding to the event included in the event list 610 is detected.

For example, the event list 610 may include a secondary cell (SCell) activation / deactivation flag, an uplink Carrier Aggregation (CA) uplink grant, A flag, an idle / connected state, and the like.

More specifically, when data of a terminal supporting the CA function is requested, the base station can allocate data to the terminal through the SCELL as needed. At this time, before allocating data to the SCell, the BS transmits a signaling for activating the SCell to the UE using a L2 (Layer 2) MAC Control Element (CE). Accordingly, the terminal receiving the signaling assumes reception of data to be performed after a predetermined time (or anticipates that consumption current or consumed power will increase sharply in order to receive data), and can prepare accordingly have. Accordingly, in this case, the signaling for activating the SCell may correspond to the event message included in the event list 610 of the present invention.

The event list 610 can be defined in advance (or in advance), and can be stored in a database (DataBase, DB). In addition, the event list 610 may be updated or changed according to a predetermined period or a certain condition. Also, the event list 610 may be updated or changed according to the user's input.

A specific procedure for predicting the consumed current or consumed power of the terminal using the protocol message on the communication and compensating for the frequency offset between the base station and the terminal will be described below with reference to FIG.

7 is a flowchart illustrating an operation of a UE for compensating a frequency offset according to an embodiment of the present invention. Fig. 7 is merely for convenience of description and does not limit the scope of the present invention.

7, when a preset (or defined) message (or communication protocol message) event occurs, the terminal (or the baseband unit included in the terminal) updates the cumulative period and frequency value of the estimated frequency offset value (Or change) period is adaptively determined.

In step S705, the terminal can calculate the SNR value for the received signal. Here, the terminal may calculate a value (or index) indicating the degree of interference (degree or level) with respect to the received signal in addition to the SNR. Also, in this case, the terminal operates in an idle state (e.g., RRC idle mode) or in a connected state (e.g., RRC connected mode).

When the SNR value is calculated, the UE can determine (or determine) whether the calculated SNR value is greater than (or is greater than) a preset threshold value. Here, the threshold value may be determined by a service provider, a service user (e.g., a user of the terminal), or a manufacturer of the terminal. The threshold value may also be set based on the current network environment.

If the UE determines that the SNR value is not greater than the threshold value, the UE can maintain a frequency offset accumulation ratio and a frequency update ratio in step S710.

In other words, in this case, the terminal determines that the received signal is good and can maintain the current setting accordingly.

Here, the cumulative ratio of frequency offsets may correspond to the cumulative length of the estimated frequency offsets described in the section for FIG. Also, maintaining the frequency update rate may mean maintaining a frequency change period to compensate for the frequency offset between the base station and the terminal.

In addition, the frequency offset accumulation ratio may mean an automatic frequency control (AFC) accumulation ratio. In this case, maintaining the frequency offset accumulation ratio may mean maintaining the existing AFC accumulation algorithm.

In addition, the frequency update rate may mean the update rate of the crystal oscillator. For example, the frequency update rate may refer to the update (or change) rate of the frequency oscillated in the VCTCXO. In this case, maintaining the frequency update rate may mean maintaining the refresh cycle of the VCTCXO.

On the other hand, if the terminal determines that the SNR value is larger than the threshold value, the terminal can check the triggering event list in step S715.

Here, the triggering event list may correspond to the event list 610 described in FIG. In other words, the terminal can identify information about events (or messages on the communication protocol) that are expected to drastically increase consumption current or power consumption.

In this case, the terminal may obtain (or collect) or manage a preset protocol message item and / or an updated (or changed) protocol message item. At this time, the terminal can collect or manage information using information previously stored in the DB.

After the terminal confirms the triggering event list, in step S720, the terminal can detect whether an event causing (or causing) abrupt consumption current or consumed power is generated. In this case, the terminal can determine whether or not the event is generated according to whether or not message signaling on the communication protocol is detected.

Here, an event causing abrupt consumption current or consumed power may be referred to as a current drain triggering event.

For example, if the terminal receives a message related to SCell activation from the base station via the MAC protocol, the terminal may predict (or detect) that an event triggering the current drain will occur.

If the UE fails to detect the occurrence of the event, the UE can maintain the frequency offset accumulation ratio and the frequency update ratio according to step S710.

On the other hand, if the UE detects the occurrence of the event, the UE decreases the frequency offset accumulation ratio and increases the frequency update rate in step S725. Here, the decrease in the frequency offset accumulation ratio may mean that the length in which the UE accumulates the estimated frequency offset is reduced. For example, the UE can accumulate the estimated frequency offset using an algorithm in which the AFC accumulation ratio is reduced.

Also, increasing the frequency update rate may mean that the frequency at which the UE changes the frequency to compensate for the frequency offset is shortened. For example, the terminal may increase the update rate of the crystal oscillator (or VCTCXO), i.e., reduce the update period of the crystal oscillator.

After step S710 and step S725, the terminal can confirm the triggering event list again in step S715. Accordingly, the terminal can perform the procedures described in FIG. 7 repeatedly.

Accordingly, the terminal can more accurately compensate the frequency offset by changing the frequency more repeatedly (or frequently) when the occurrence of abrupt consumption current or consumed power is predicted. In other words, the terminal can more quickly track the frequency offset between the base station and the terminal and compensate for the frequency offset accordingly.

According to the above procedure, the UE can adaptively determine (or control) the cumulative ratio of the estimated frequency offset and the period (or frequency update rate) to which the frequency compensation is applied.

In the case of FIGS. 6 and 7, it is possible to predict the abrupt consumption current or consumed power by using the protocol message on the communication, thereby compensating the frequency offset.

Alternatively, a method of predicting abrupt consumption current or power consumption by adding a separate hardware configuration (or device) or a software configuration and compensating accordingly frequency offset will be described in FIGS. 8 and 9 below.

A method of compensating for frequency offset using a hardware configuration or software configuration that measures power consumption or power consumption

8 illustrates an apparatus for compensating for frequency offset according to another embodiment of the present invention. Fig. 8 is merely for convenience of explanation and does not limit the scope of the present invention.

8, RF unit 802, baseband unit 804, and crystal oscillator 806, respectively, correspond to RF unit 502, baseband unit 504, and crystal oscillator 506 of FIG.

However, unlike Figures 5 and 6, the apparatus shown in Figure 8 further includes a current / power measurement unit 808. The current / power measurement unit 808 may measure the current or power value (or amount) consumed at the RF unit 802 and / or the baseband unit 804, i.e., the terminal. Thus, the terminal can measure the change amount (change value) of the consumed current or the consumed power. Accordingly, the terminal can predict that abrupt consumption current or consumed power will be generated.

Here, the current / power measurement unit 808 may be constituted by a measurement sensor or a measurement element.

In FIG. 8, a hardware configuration (or current / power measurement unit 808) for efficient frequency offset compensation is shown, but a terminal can measure consumption current or power consumption using a software configuration. For example, the terminal can measure the consumed current or consumed power of the terminal using a current measuring loop or a power measuring loop. In addition, the terminal can measure the consumed current or the consumed power through the post-processing operation in the baseband unit 804. [

A specific procedure for predicting the consumed current or consumed power of the terminal using the hardware configuration and / or the software configuration and compensating the frequency offset accordingly will be described below with reference to FIG.

9 is a flowchart illustrating an operation of a UE for compensating for a frequency offset according to another embodiment of the present invention. Fig. 9 is merely for convenience of explanation and does not limit the scope of the present invention.

9, the terminal (or the baseband unit included in the terminal) adaptively determines the update period of the accumulation period and the frequency value of the estimated frequency offset value based on the consumed current or consumed power of the measured terminal Case is assumed.

In step S905, the terminal can determine whether the calculated SNR value is greater than a preset threshold value.

Also, if the UE determines that the SNR value is not greater than the threshold value, the UE can maintain the frequency offset accumulation ratio and the frequency update rate in step S910.

Here, the operation of the terminal in steps S905 and S910 is similar to that of the terminal in steps S705 and S710 in FIG. 7, and thus a detailed description thereof will be omitted.

On the other hand, if the terminal determines that the SNR value is larger than the threshold value, the terminal can measure (or calculate) the consumed current or consumed power in step S915. Here, the terminal can use the current / power measurement unit 808 or the software configuration in Fig.

In this case, the terminal can measure the consumed current or the consumed power in a predetermined time unit. Here, the constant time unit may mean a time unit (or a measurable unit) in which the terminal can measure the consumed current or consumed power.

If the terminal measures the consumed current or the consumed power, the terminal can calculate the deviation value of the consumed current or the consumed power in step S920. For example, the terminal may calculate the deviation value by comparing the measured value of the consumed current or the consumed power with the previously measured value in the measurable unit.

More specifically, the difference (positive value or negative value) between the previously measured consumed current or consumed power value and the currently measured consumed current or consumed power value can be calculated as a deviation value.

Here, the deviation value may mean a gradient value of measured values for each measurable unit.

Using the calculated deviation value, the terminal can predict that the consumed current or consumed power of the terminal will increase sharply.

After the terminal calculates the deviation value of the consumed current or the consumed power, the terminal can compare the calculated deviation value with a predetermined threshold value in step S925. Here, the predetermined threshold may be determined by a service provider, a service user (e.g., a user of the terminal), or a manufacturer of the terminal. Also, the preset threshold may be set based on the current network environment.

If the terminal determines that the calculated deviation value is not greater than a predetermined threshold value, the terminal can maintain the frequency offset accumulation ratio and the frequency update ratio in step S910.

On the other hand, if the terminal determines that the calculated deviation value is larger than a predetermined threshold value, the terminal decreases the frequency offset accumulation ratio and increases the frequency update ratio in step S930. In this case, the operation of the terminal in step S930 is similar to the operation of the terminal in step S725 of FIG. 7, so a detailed description thereof will be omitted.

After step S910 and step S930, the terminal can measure the consumed current or consumed power of the terminal in step S915. Accordingly, the terminal can perform the procedures described in FIG. 9 repeatedly.

Accordingly, when a sudden consumption current or consumed power is predicted to be generated, the terminal can more accurately compensate the frequency offset by changing the frequency more frequently. In other words, the terminal may track the frequency offset between the base station and the terminal more quickly, thereby compensating for the frequency offset.

According to the above procedure, the UE can adaptively determine (or control) the cumulative ratio of the estimated frequency offset and the period (or frequency update rate) to which the frequency compensation is applied.

In various embodiments of the present invention, the performance of compensating the frequency offset may vary depending on the setting of the threshold in step S925.

For example, if the threshold value of step S925 is set to a large value, the terminal performs the operation of step S910 more than the operation of step S930. Accordingly, the performance for compensating for the frequency offset can be enhanced. In this case, however, the overhead of the UE for compensating for the frequency offset may be increased.

For example, if the threshold value of step S925 is set to a small value, the terminal performs the operation of step S930 more than the operation of step S910. Accordingly, the performance of compensating for the frequency offset can be lowered. In this case, however, the overhead of the UE for compensating for the frequency offset can be reduced.

The two methods described above can predict sudden power consumption or power consumption using hardware configuration or software configuration, respectively, or using messages on communication protocols.

Alternatively, a method in which the terminal combines (or concatenates and merges) the above two methods to predict a sudden consumption current or consumed power, and thereby compensate for the frequency offset will be described with reference to FIGS. 10 and 11. FIG.

A method of compensating a frequency offset by combining the above two methods

10 illustrates an apparatus for compensating for frequency offset in accordance with another embodiment of the present invention. Fig. 10 is merely for convenience of explanation and does not limit the scope of the present invention.

10, the RF unit 1002, the baseband unit 1004, the crystal oscillator 1006, the communication protocol 1010, and the event list 1012 are respectively coupled to the RF unit 602, the baseband unit 604, the crystal oscillator 606, the communication protocol 608, Corresponding to the event list 610. Also, the current / power measurement unit 1008 corresponds to the current / power measurement unit 808 in Fig.

8, the current / power measurement unit 1008 can be replaced with a software configuration that measures the consumed current or consumed power of the terminal.

In addition, a method of compensating for frequency offset using a communication protocol message and a method of compensating for frequency offset using a hardware configuration or software configuration may be performed simultaneously or separately.

10, the terminal can update (or manage) the event list 1012 based on the consumed current or the consumed power measured by the current / power measurement unit 1008. [ Thus, the terminal can increase the accuracy of the method using the communication protocol message.

A specific procedure for predicting the consumed current or consumed power of the terminal using the apparatus shown in FIG. 10 and compensating the frequency offset accordingly will be described with reference to FIG.

11 is a flowchart illustrating an operation of a UE that compensates for a frequency offset according to another embodiment of the present invention. Fig. 11 is merely for convenience of explanation, and does not limit the scope of the present invention.

Referring to FIG. 11, operations of the terminals in steps S1105, S1110, S1125, S1130, and S1140 are performed in steps S705, S710, S715, S720, The detailed description thereof will be omitted.

The operations of the terminal in steps S1115 and S1120 are similar to those of the terminal in steps S915 and S920 of FIG. 9, respectively, so that a detailed description thereof will be omitted.

In the case of FIG. 11, steps S1115, S1120, and S1125 are sequentially performed, but the order in which the three steps are performed may be changed. For example, after the operation of step S1125 is performed first, steps S1115 and S1120 may be performed.

If the terminal determines in step S1130 that the deviation value is larger than the threshold value, the terminal can determine whether an occurrence of an event (or an event occurrence message) is detected in step S1135.

In this case, the terminal may use message signaling associated with the event included in the event list 1012 of FIG. For example, the terminal can determine that an event occurrence has been detected when a message related to the event included in the event list 1012 is received from the base station.

If the UE determines that the calculated deviation value is larger than the threshold value and detects the occurrence of the event, the UE decreases the frequency offset accumulation ratio and increases the frequency update ratio in step S1140. In this case, the terminal determines whether or not the detected event (or the currently generated event) is an event (a triggering event list or an event list 1012) that rapidly increases (or validates) It can be confirmed that it is included.

On the other hand, if the terminal determines that the calculated deviation value is larger than the threshold value and does not detect the occurrence of the event, the terminal stores the information on the currently generated event in step S1145, Can be added. For example, the terminal may store the message signaling information for the currently generated event in the event list.

More specifically, the terminal can identify that the currently generated event is not included in the event list even though it is a sudden increase (or valid) event of consuming current or consumed power. Accordingly, the terminal may add information about the event to the event list in case the event occurs again in the future.

After the terminal adds information on the event to the event list, the terminal decreases the frequency offset accumulation ratio and increases the frequency update rate in step S1140.

On the other hand, if the UE determines that the calculated deviation value is not greater than the threshold value and does not detect the occurrence of the event, the UE can maintain the frequency offset accumulation ratio and the frequency update rate in step S1110. In this case, the terminal can confirm that the currently generated event is not included in the event list as an event that does not abruptly increase (or invalidate) the consumption current or consumed power of the terminal.

On the other hand, if the terminal determines that the calculated deviation value is not greater than the threshold value and detects the occurrence of the event, the terminal stores the information about the currently generated event in step S1155, Can be deleted. For example, the terminal may delete the message signaling information for the currently generated event from the event list.

More specifically, the terminal can identify that the currently generated event is included in the event list even though it is not a sudden increase (or valid) event of consumption current or power consumption. Accordingly, the terminal can delete information on the event from the event list in case the event occurs again in the future.

After the UE deletes the information on the event from the event list, the UE can maintain the frequency offset accumulation ratio and the frequency update rate in step S1110.

After step S1110 and step S1140, the terminal can measure the consumed current or consumed power of the terminal according to step S1115. Accordingly, the terminal can perform the procedures described in FIG. 11 repeatedly.

Accordingly, when a sudden consumption current or consumed power is predicted to be generated, the terminal can more accurately compensate the frequency offset by changing the frequency more frequently. In other words, the terminal may track the frequency offset between the base station and the terminal more quickly, thereby compensating for the frequency offset.

According to the above procedure, the UE can adaptively determine (or control) the cumulative ratio of the estimated frequency offset and the period (or frequency update rate) to which the frequency compensation is applied. Also, through the above-described procedure, the terminal may manage (or update) the event list so that it contains only information on valid events.

12 shows an operation flowchart of a UE for correcting a frequency offset according to various embodiments of the present invention. Fig. 12 is merely for convenience of explanation and does not limit the scope of the present invention.

Referring to FIG. 12, it is assumed that a frequency offset occurs between a base station and a terminal based on a signal received from the base station.

In step S1205, the UE can estimate the frequency offset between the BS and the UE. Here, the terminal can calculate the estimated frequency offset based on the signal received from the base station. In this case, the UE can estimate the frequency offset using the baseband unit described in FIGS.

Further, in various embodiments of the present invention, the terminal may estimate the frequency offset based on the SNR value for the signal received from the base station. For example, a UE can estimate a frequency offset between a Node B and a UE when the SNR value is greater than a preset threshold value. In this case, the operation of the terminal is similar to the operation of the terminal described in step S705 of FIG.

After the UE estimates the frequency offset, in step S1210, the UE can generate an oscillation frequency according to a frequency offset compensation period.

Here, the generated oscillation frequency may refer to a frequency at which the frequency offset estimated in step S 1205 is reflected. Also, the frequency offset compensation period may mean a period in which the oscillator updates the oscillation frequency to compensate for the frequency offset.

The UE can compensate the estimated frequency offset using the oscillation frequency. Here, the oscillation frequency may refer to a frequency generated by the crystal oscillator (for example, VCTCXO) described above.

Thereafter, in step S1215, the UE can confirm whether or not an event triggering the change of the frequency offset compensation period is detected.

Here, an event that triggers a change in the frequency offset compensation period may mean an event that abruptly increases the current or power consumed in the terminal.

Also, the terminal can use a preset event list to confirm the event. Here, the event list may include information on a message on at least one communication protocol associated with at least one event that triggers a change in the frequency offset compensation period. The event list is similar to the event list 610 of FIG. 6 and / or the event list 1012 of FIG.

Also, in this case, the terminal can confirm the event as it receives the message on the at least one communication protocol from the base station.

The operation of the terminal in step S1210 is similar to the operation of the terminal in step S720 of FIG. 7 and / or the operation of the terminal in steps S1135 and S1150 of FIG.

After the terminal confirms the event, if the event is detected in step S1215, the terminal can change the frequency offset compensation period in step S1205.

For example, the terminal may accumulate the estimated frequency offset based on the reduced accumulation ratio, and may reduce the frequency offset compensation period based on the accumulated frequency offset. Here, the reduced accumulation ratio may mean that the rate at which the currently estimated frequency offset value is reflected is compared with the previously estimated frequency offset values.

The operation of the terminal in step S1215 is similar to the operation of the terminal in step S725 of FIG. 7 and / or step S1140 of FIG.

Further, in various embodiments of the present invention, in order to change the frequency offset compensation period, at least one value of current or power currently consumed in the terminal may be calculated. In this case, the terminal can use a hardware configuration or a software configuration. Also, in this case, the terminal can calculate the deviation value for current or power using the calculated value, and compare the two values.

In this case, the terminal can perform operations similar to those described in Figs. 9 and 11.

Also, in various embodiments of the present invention, if an event is not detected in step S1215, the UE can maintain a frequency offset compensation period. In this case, the operation of the terminal is similar to the operation in step S1110 of FIG.

Also, in various embodiments of the present invention, if the calculated deviation value is greater than the threshold value, but the event is not detected in step 1215, the terminal transmits information on a message on the communication protocol related to the currently generated event to the event list (Or add) it. In this case, the operation of the terminal is similar to the operation in step S1145 of FIG.

Also, in various embodiments of the present invention, if the event is not detected in step S1215 and the calculated deviation value is less than or equal to the threshold value, the terminal can maintain the frequency offset compensation period. In this case, the operation of the terminal is similar to the operation in step S1110 of FIG.

Also, in various embodiments of the present invention, if an event is detected in step S1215, but the calculated deviation value is less than or equal to the threshold, the terminal may delete information about the message on the communication protocol associated with the detected event from the event list have. In this case, the operation of the terminal is similar to the operation in step S1155 in Fig.

In addition, in various embodiments of the present invention, if the SNR value calculated for the signal received from the base station by the terminal is less than or equal to the threshold, the terminal can maintain the frequency offset compensation period. In this case, the operation of the terminal is similar to the operation in step S1105 in Fig.

13A and 13B show graphs of quality and frequency for signals received at a terminal in accordance with various embodiments of the present invention. 13A and 13B are merely for convenience of description and do not limit the scope of the present invention.

13A and 13B, it is assumed that a terminal supporting a CA receives a signal from a primary cell (PCell) and a secondary cell (SCELL). In addition, the graphs shown in Figs. 13A and 13B are determined based on the measured values at the terminal, and the horizontal axis (x axis) of the graphs shown in Figs. 13A and 13B means time.

13A and 13B, a graph 1301 and a graph 1302 show graphs of Received Signal Strength Indicator (RSSI) of a signal (e.g., a reference signal (RS)) received from a PCell.

Graph 1303 and graph 1304 also show graphs of SNRs of signals received from PCell.

Graph 1305 and graph 1306 also show graphs for AFC reports on signals received from PCell.

Graph 1307 and graph 1308 also show graphs for RSSI for signals received from SCell.

Graphs 1309 and 1310 also show graphs of SNRs of signals received from SCell.

13A and 13B show values (e.g., RSSI, SNR, AFC report) for a certain period of time from the time when the SCell is activated. Here, the time point at which the SCell is activated may indicate a time point at which the terminal consumes current or power consumption sharply increases.

13A shows graphs for compensating the frequency offset without using the method of predicting the abrupt consumption current or consumed power described above.

Referring to FIG. 13A, at the box (or at the time SCell is activated), the quality (e.g., RSSI, SNR) of the signal received from PCell and SCell is lowered.

More specifically, as shown in the graph 1305, since the terminal does not control (change or update) the frequency (or compensate the frequency offset) by predicting that the terminal will rapidly increase the consumed current or consumed power, The SNR value of the signal received from the SCell is reduced to about 24 dB from about 28 decibels (dB).

On the other hand, FIG. 13B shows graphs for compensating the frequency offset using a method of predicting the abrupt consumption current or consumed power described above.

13B, the quality (e.g., RSSI, SNR) of the signal received from PCell and SCell is lowered at the box (or at the time SCell is activated).

However, as shown in the graph 1306, since the terminal estimates that the consumed current or consumed power will increase rapidly, the SNR value of the signal received from the SCell changes from about 28dB to about 26dB .

Therefore, according to the graphs of FIGS. 13A and 13B, when the control of the frequency (or the compensation of the frequency offset) is anticipated in advance of the occurrence of the abrupt consumption current or the consumption power as proposed in the present invention, It can be confirmed that the quality is higher.

Apparatus to which the present invention may be applied

14 illustrates a block diagram of a wireless communication apparatus according to an embodiment of the present invention.

Referring to FIG. 14, a wireless communication system includes a network node 1410 and a plurality of terminals (UE) 1420.

The network node 1410 includes a processor 1411, a memory 1412, and a communication module 1413. Processor 1411 implements the functions, processes, and / or methods previously suggested in FIGS. 1-13. The layers of the wired / wireless interface protocol may be implemented by the processor 1411. The memory 1412 is coupled to the processor 1411 and stores various information for driving the processor 1411. The communication module 1413 is connected to the processor 1411 to transmit and / or receive a wired / wireless signal. In particular, when the network node 1410 is a base station, the communication module 1413 may include a radio frequency unit for transmitting / receiving radio signals.

The terminal 1420 includes a processor 1421, a memory 1422 and a communication module (or RF section) 1423. Processor 1421 implements the functions, processes, and / or methods suggested earlier in FIGS. 1-13. The layers of the air interface protocol may be implemented by the processor 1421. The memory 1422 is coupled to the processor 1421 to store various information for driving the processor 1421. Communication module 1423 is coupled to processor 1421 to transmit and / or receive wireless signals.

The memories 1412 and 1422 may be internal or external to the processors 1411 and 1421 and may be coupled to the processors 1411 and 1421 in various well known means. Also, the network node 1410 (if a base station) and / or the terminal 1420 may have a single antenna or multiple antennas.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in memory and driven by the processor. The memory is located inside or outside the processor and can exchange data with the processor by various means already known.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. Accordingly, the foregoing detailed description is to be considered in all respects illustrative and not restrictive. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

In the wireless communication system of the present invention, the method of compensating the frequency offset between the base station and the terminal has been described with reference to an example applied to the 3GPP LTE / LTE-A system. However, the present invention is applicable to various wireless communication systems other than the 3GPP LTE / LTE- It is possible.

Claims (12)

A method of compensating for a frequency offset in a wireless communication system, the method being performed by a terminal,
Estimating a frequency offset based on a signal received from a base station;
Generating an oscillation frequency of the UE by reflecting the estimated frequency offset according to a frequency offset compensation period;
Determining whether an event triggering a change of the frequency offset compensation period is detected;
And changing the frequency offset compensation period when the event is detected. The method according to claim 1,
Estimating the frequency offset based on the received signal from the base station,
Calculating a signal-to-noise ratio (SNR) value for the received signal;
And estimating the frequency offset if the calculated SNR value is greater than a preset threshold value. The method according to claim 1,
And maintaining the frequency offset compensation period if the event is not detected. The method according to claim 1,
The process of determining whether the event is detected includes:
And identifying the event by using a preset event list,
Wherein the preset event list includes information about a message on at least one communication protocol associated with at least one event that triggers a change in the frequency offset compensation period. 5. The method of claim 4,
The method of claim 1, wherein the detecting of the event using the preset event list comprises:
And receiving a message on the at least one communication protocol from the base station. 6. The method of claim 5,
Wherein the step of changing the frequency offset compensation period comprises:
Accumulating the estimated frequency offset based on the reduced accumulation ratio;
And decreasing the frequency offset compensation period based on the accumulated frequency offset. 5. The method of claim 4,
Wherein the step of changing the frequency offset compensation period comprises:
Calculating at least one value of a current consumption current or a current consumption power of the terminal;
Calculating a deviation value with respect to consumed current or consumed power by using the calculated at least one value;
And changing the frequency offset compensation period if the calculated deviation value is greater than a predetermined threshold value. 8. The method of claim 7,
If the event is not detected, storing information on a message on a communication protocol related to a currently generated event in the event list. 8. The method of claim 7,
And if the event is not detected and the calculated deviation value is less than or equal to a predetermined threshold value, maintaining the frequency offset compensation period. 8. The method of claim 7,
Deleting information on a message on a communication protocol related to the event from the event list if the calculated deviation value is less than or equal to a predetermined threshold value;
And maintaining the frequency offset compensation period. 3. The method of claim 2,
And maintaining the frequency offset compensation period if the calculated SNR value is less than or equal to a preset threshold value. A terminal for compensating a frequency offset in a wireless communication system,
A transmission / reception unit for transmitting / receiving a radio signal,
And a processor operatively connected to the transceiver,
The processor comprising:
Estimating a frequency offset based on the signal received from the base station,
Generates an oscillation frequency of the terminal by reflecting the estimated frequency offset according to a frequency offset compensation period,
Whether or not an event triggering a change of the frequency offset compensation period is detected,
And to change the frequency offset compensation period when the event is detected.

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