WO2015053528A1

WO2015053528A1 - Rotation pre-coder based self-interference cancellation method and apparatus in wireless access system supporting full duplex radio scheme

Info

Publication number: WO2015053528A1
Application number: PCT/KR2014/009414
Authority: WO
Inventors: 김진민; 이해순; 정재훈; 김기태; 홍대식; 김동규
Original assignee: 엘지전자 주식회사; 연세대학교 산학협력단
Priority date: 2013-10-07
Filing date: 2014-10-07
Publication date: 2015-04-16
Also published as: KR20160067096A

Abstract

The present invention provides methods for cancelling a rotation pre-coder based self-interference in FDR system and apparatuses supporting the same. A method for cancelling a rotation pre-coder based self-interference by a terminal in a wireless access system supporting a full-duplex radio (FDR) scheme, as an embodiment of the present invention, may comprise the steps of: receiving a first reference signal from a base station; receiving, by a terminal, a second reference signal transmitted from the terminal; estimating a preferred channel on the basis of the first reference signal and a self-interference channel on the basis of the second reference signal; measuring a rotation angle on the basis of a first angle which is perpendicular to a detection axis with respect to the preferred channel and a second angle with respect to the interference channel; rotating the self-interference channel using a rotation angle; and cancelling an interference signal on the basis of the rotated self-interference channel. In this case, the first angle and the second angle may be a value measured from 0 degrees of real-number axis.

Description

【Specification】

[Name of invention]

Rotating Precoder-based Magnetic Interference Cancellation Method and Apparatus in Radio Access System Supporting Full Duplex Radio System

Technical Field

[1] The present invention relates to methods for eliminating magnetic interference based on a rotating precoder in a full duplex radio (FDR) system as one of wireless access systems and apparatuses for supporting the same.

Background Art

[2] Wireless access systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless access system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier SC-FDMA. frequency division, multiple access) systems.

[3] In other words, in a conventional radio access system, a base station or a terminal divides a radio resource for transmitting a signal into a frequency division duplex (FDD) scheme or a time division duplex (TDD). Communication is performed using a half duplex radio (HDR) scheme.

However, in this half duplex (HDR) communication scheme, the terminal and / or the base station cannot simultaneously receive and transmit within the same frequency / time resource. Therefore, the introduction of a full duplex radio (FDR) communication scheme for efficient use of resources has been proposed. In the FDR communication method, a base station and / or a terminal simultaneously transmits and receives different signals in the same frequency / time resource region.

[5] However, in the FDR communication environment, since the base station and / or the terminal perform data transmission and reception simultaneously through the same resource area, self-interference in which a signal transmitted by the base station is received through its reception antenna is used. This happens. In addition, when the FDR region is configured together with the HDR region, mutual interference may occur. Accordingly, there is a need for efficient methods for removing magnetic interference in a communication environment supporting the FDR scheme and devices supporting the same.

[Detailed Description of the Invention]

[Technical problem]

An object of the present invention is to provide a method for efficient communication.

Another object of the present invention is to provide methods for removing magnetic interference in an FDR system.

It is still another object of the present invention to provide a method of canceling magnetic interference based on a rotating precoder in an FDR system.

Another object of the present invention is to provide an apparatus supporting these methods.

[11] The technical objects to be achieved in the present invention are not limited to the above-mentioned matters, and other technical problems not mentioned above are common in the art to which the present invention belongs from the embodiments of the present invention described below. It can be considered by those who have knowledge. ·

Technical Solution

[12] The present invention provides methods for removing magnetic interference based on a rotating precoder in an FDR system and apparatuses for supporting the same.

According to an aspect of the present invention, in a wireless access system supporting a full dual radio (FDR) scheme, a method for removing self-interference based on a rotation precoder by a terminal includes: receiving a first reference signal from a base station; And receiving, by the terminal, the second reference signal transmitted from the terminal, estimating a preferred channel based on the first reference signal, estimating a self-interfering channel based on the second reference signal, and Measuring a rotation angle based on a first angle perpendicular to the detection axis and a second angle with respect to the interference channel, rotating the magnetic interference channel using the rotation angle, and interference based on the rotated magnetic interference channel And removing the signal. At this time, the first angle and the second angle may be a value measured from the angle 0 of the real axis. [14] The method includes retransmitting a second reference signal, acquiring information about an error angle using the second reference signal transmitted again, and compensating a rotation angle based on the information on the error angle. It may further include.

At this time, the remaining steps except for removing the interference signal may be repeatedly performed a predetermined number of times.

[16] In another aspect of the present invention, a terminal for eliminating rotational precoder-based self-interference in a radio access system supporting a full duplex radio (FDR) scheme controls a transmitter, a receiver, and the transmitter and the receiver, It may include a processor to support the elimination of interference based on the rotation precoder. At this time, the processor controls the receiver to receive the first reference signal from the base station, controls the receiver to receive the second reference signal transmitted from the transmitter, estimates the preferred channel based on the first reference signal, 2 Estimates the self-interference channel based on the reference signal, measures the rotation angle based on the first angle perpendicular to the detection axis for the preferred channel and the second angle for the interference channel, and uses the rotation angle for self-interference. The channel may be rotated and the interference signal may be canceled based on the rotated magnetic interference channel. In this case, the first angle and the second angle may be values measured from the angle 0 of the real axis.

The processor controls the transmitter to retransmit the second reference signal, and controls the receiver to obtain the information on the error angle by receiving the second reference signal transmitted again, and based on the information on the error angle. It can be further configured to compensate for the rotation angle.

In this case, the processor may repeatedly perform the interference canceling operation a predetermined number of times. [19] In the above aspects of the present invention, the error angle ^θ is calculated as shown in the following equation, where ^{0err = sm} (l ^ ll ^ l) ' ^s _sl indicates the rotated magnetic interference channel toward the detection axis. Means the projected value, / means the assumed self-interference channel, the terminal.

In this case, the first angle is an angle formed by the real axis and the rotated magnetic interference channel, and is composed of an angle at which symbols projected on the detection axis form an equal interval.

[21] The above-described aspects of the present invention are merely some of the preferred embodiments of the present invention, and various embodiments in which the technical features of the present invention are reflected will be described below by those skilled in the art. It can be derived and understood based on the detailed description of the invention. Advantageous Effects

According to the embodiments of the present invention, the following effects are obtained.

First, efficient communication can be performed in a wireless access system supporting FDR.

Second, magnetic interference, which is the biggest problem in FDR systems, can be eliminated.

Third, in the present invention, when the elimination of the necessary magnetic interference in a full-duplex communication environment is required, the magnetic interference channel can be rotated by using a precoder to increase the throughput of the system through the improvement of the magnetic interference cancellation performance. have. This can improve the self-interference cancellation gain and improve system throughput and BER, especially in environments with high SNR and high magnitudes of self-interference, such as low SIR environments.

Fourth, it is possible to optimize the performance of the SP-SIC technique by considering the complexity and system throughput by setting the number of iterations according to the channel environment.

Effects obtained in the embodiments of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are described in the following description of the embodiments of the present invention. It can be clearly derived and understood by those skilled in the art. In other words, unintended effects of practicing the present invention can also be derived by those skilled in the art from the embodiments of the present invention.

[Brief Description of Drawings]

It is included as part of the detailed description to help understand the present invention, and the accompanying drawings provide various embodiments of the present invention. In addition, the accompanying drawings are used to describe embodiments of the present invention with a detailed description.

FIG. 1 is a diagram for explaining physical channels and a signal transmission method using the same.

2 shows the structure of a radio frame.

3 illustrates a resource grid for a downlink slot.

4 shows a structure of an uplink subframe.

5 shows a structure of a downlink subframe. 6 shows a subframe structure of an LTE-A system according to cross carrier scheduling.

7 is a layout diagram illustrating an example of a wireless access system supporting FDR.

8 is a diagram illustrating a conceptual diagram of self-interference in an FDR system.

FIG. 9 is a diagram illustrating an example of a method of rotating a magnetic interference channel through RP-SCI. FIG.

FIG. 10 is a diagram illustrating an example of a method of detecting each symbol on a detection axis using a quadrature phase shift keying (QPSK) symbol. FIG. 1 is a diagram summarizing an example of a method of eliminating interference based on a rotating precoder in a terminal.

12 is a diagram illustrating the average processing performance of a terminal according to embodiments of the present invention according to a channel estimation error.

FIG. 13 shows a comparison of performance when a 12-bit ADC is used without modeling channel estimation errors as random variables through variance.

The apparatus described with reference to FIG. 14 is a means in which the methods described with reference to FIGS. 1 to 13 may be implemented.

[Form for implementation of invention]

The present invention described in detail below defines a structure of an FDR region in a full duplex radio (FDR) system as one of wireless access systems. The present invention also provides methods and apparatuses for transmitting allocation information on a configured FDR region.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments It may be included in other embodiments, or may be substituted for the constitution or features of other embodiments.

In the description of the drawings, procedures or steps that may obscure the subject matter of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Embodiments of the present invention have been described with reference to data transmission / reception relations between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. Certain operations described as being performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a mobile station in a network composed of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.

Further, in embodiments of the present invention, a terminal may be a user equipment (UE), a mobile station (MS), a subscriber station (SS), or a mobile subscriber station (MSS) Mobile. It may be replaced with terms such as Subscriber Station, Mobile Terminal, or Advanced Mobile Station (AMS).

In addition, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station can be a transmitting end and a base station can be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.

[50] Embodiments of the present invention provide at least one of an IEEE 802.xx system, a 3rd Generation Partnership Project (3GPP) system, a 3GPP LTE system, and a 3GPP2 system, which are wireless access systems. In particular, embodiments of the present invention may be supported by 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321 and 3GPP TS 36.331 documents. That is, obvious steps or portions not described among the embodiments of the present invention may be described with reference to the above documents. In addition, all terms disclosed in this document may be described by the above standard document.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

In addition, specific terms used in the embodiments of the present invention are provided to aid the understanding of the present invention, and the use of the specific terms may be changed to other forms without departing from the technical spirit of the present invention. Can be.

For example, in embodiments of the present invention, the magnetic interference signal may be used in the same meaning as the interference signal. In particular, unless otherwise stated, the interference signal is a self-interference signal, and means a signal in which a signal transmitted from a transmission antenna of a specific terminal or a base station is received by its reception antenna.

The following techniques are code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). It can be applied to various wireless access systems such as).

CDMA may be implemented by radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may 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 is IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-21, E-UTRA (Evolved UTRA) and the like can be implemented in a wireless technology.

[56] UTRA is a part of Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. The LTE-A (Advanced) system is an improved system of the 3GPP LTE system. In order to clarify the description of the technical features of the present invention, embodiments of the present invention will be described based on the 3GPP LTE / LTE-A system, but can also be applied to IEEE 802.16e / m system and the like.

[57] 1. 3GPP LTE / LTE_A System

In a wireless access system, a terminal receives information from a base station through downlink (DL) and transmits information to a base station through uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist according to the type / use of the information they transmit and receive.

[59] 1.1 General

FIG. 1 is a diagram for explaining physical channels that can be used in embodiments of the present invention and a signal transmission method using the same.

In the state in which the power is turned off, the terminal is powered on again or enters a new cell, and performs an initial cell search operation such as synchronizing with the base station in step S1. To this end, the UE receives a Primary Synchronization Channel (P-SCH) and a Secondary Synchronization Channel (S-SCH) from the base station, synchronizes with the base station, and obtains information such as a cell ID. Thereafter, the terminal may receive a physical broadcast channel (PBCH) signal from the base station to obtain broadcast information in a cell.

Meanwhile, the UE may check a downlink channel state by receiving a downlink reference signal (DL RS) in an initial cell search step.

After completing the initial cell discovery, the UE receives a physical downlink control channel (PDCCH) and a physical downlink control channel (PDSCH) according to physical downlink control channel information in step S12. By doing so, more specific system information can be obtained.

Subsequently, the terminal may perform a random access procedure such as step S13 to step S16 to complete the access to the base station. To this end, the UE transmits a preamble through a physical random access channel (PRACH) (S13), and through a physical downlink control channel and a physical downlink shared channel thereto, The answer message may be received (S14). In case of contention-based random access, the UE may perform contention resolution such as transmitting additional physical random access channel signals (S15) and receiving physical downlink control channel signals and physical downlink shared channel signals (S16). Procedure).

After performing the above-described procedure, the UE can receive a physical downlink control channel signal and / or a physical downlink shared channel signal (S) and a physical uplink shared channel (A) as a general uplink / downlink signal transmission procedure. A PUSCH (physical uplink shared channel) signal and / or a physical uplink control channel (PUCCH) signal may be transmitted (S18).

The control information transmitted from the terminal to the base station is collectively referred to as uplink control information (UCI). UCI includes HARQ-ACK / NACK (Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK), SR (Scheduling Request), Channel Quality Indication (CQI), Precoding Matrix Indication (PMI), and Rank Indication (RI) information.

In the LTE system, UCI is generally transmitted periodically through a PUCCH, but may be transmitted through a PUSCH when control information and traffic data are to be transmitted at the same time. In addition, the UCI may be aperiodically transmitted through the PUSCH by the network request / instruction.

2 shows a structure of a radio frame used in embodiments of the present invention.

2 (a) shows a frame structure type 1. The type 1 frame structure can be applied to both a full duplex Frequency Division Duplex (FDD) system and a half duplex FDD system.

[71] A radio frame has a length of = 30 ⁷ 200.7 = 10 ms, iot ⁼ 15360 · ^τ ₅ ^{= 0} '20 equal lengths of ^{5 ms} and indexed from 0 to 19 It consists of a slot. One subframe is defined as two consecutive slots, and the i-th subframe includes slots corresponding to 2i and 2i + l. That is, a radio frame is composed of 10 subframes. The time taken to transmit one subframe is called a transmission time interval (TTI). Here, T _s represents a sampling time and is represented by TV = l / (15kHzx2048) = 3.2552xl0- ⁸ (about 33ns). The slot includes a plurality of OFDM symbols or SC-FDMA symbols in the time domain and a plurality of resource blocks in the frequency domain.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. Since 3GPP LTE uses OFDMA in downlink, the OFDM symbol is for representing one symbol period. The OFDM symbol may be referred to as one SC-FDMA symbol or symbol period. A resource block is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot. In a full-duplex FDD system, 10 subframes may be used simultaneously for downlink transmission and uplink transmission during each 10 ms period. At this time, uplink and downlink transmission are separated in the frequency domain. On the other hand, in the case of a half-duplex FDD system, the terminal cannot simultaneously transmit and receive.

The structure of the radio frame described above is just one example, and the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of OFDM symbols included in the slot may be variously changed. have.

2 (b) shows a frame structure type 2. Type 2 frame structure is applied to the TDD system. One radio frame (radio frame) 7 = ³⁰ 0, ⁷² has a length of 7 = 10 ms, consists of _two half-frames (half-frame) with a 1 ⁵³⁶ 00 '7 = ⁵ ms long. Each half frame consists of five subframes having a length of ^{3 () 72} 0 = 1 ms. the i-th sub-frames is 2, and _{i +} composed of each _ot ₌ 15 ³ 60 _s = coming from the _two slots having a length of ⁵ ms for the _1. Here, T _s represents a sampling time and is represented by T _s = l / (15kHzx2048) = 3.2552x10-8 (about 33ns).

The type 2 frame includes a special subframe consisting of three fields: a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). Here, the DwPTS is used for initial cell search, synchronization or channel estimation in the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

The following Table 1 shows the structure of the special frame (the length of DwPTS / GP / UpPTS).

[78] [Table 1]

3 is a diagram illustrating a resource grid for a downlink slot that may be used in embodiments of the present invention.

Referring to FIG. 3, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, one downlink slot includes seven OF VI symbols and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element is a resource element on the resource grid, and one resource block includes 12 × 7 resource elements. The number NDL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth. The structure of the uplink slot may be the same as the structure of the downlink slot.

4 shows a structure of an uplink subframe that can be used in embodiments of the present invention.

4, an uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is allocated a PUCCH carrying uplink control information. The data area is allocated with a PUSCH carrying user data. In order to maintain a single carrier characteristic, one UE does not simultaneously transmit a PUCCH and a PUSCH. The PUCCH for one UE is allocated an RB pair in a subframe. RBs belonging to an RB pair have different portions in each of the two slots. Occupies a carrier. This RB pair allocated to the PUCCH is said to be frequency hopping at the slot boundary (slot boundary).

5 shows a structure of a downlink subframe that can be used in embodiments of the present invention.

Referring to FIG. 5, in the first slot of a subframe, OF is a control region in which up to three OFDM symbols are allocated control channels from VI symbol index 0, and the remaining OFDM symbols are data to which a PDSCH is allocated. This is a data region. An example of a downlink control channel used in 3GPP LTE includes a Physical Control Format Indicator Channel (PCFICH), a PDCCH, and a Physical Hybrid-ARQ Indicator Channel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols (ie, the size of the control region) used for transmission of control channels in the subframe. PHICH is a male answer channel for the uplink, and carries an ACK (Acknowledgement) / NACK (Negative-Acknowledgentent) signal for a hybrid automatic repeat request (HARQ). Control information transmitted through the PDCCH is called 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 a certain terminal group.

[87] 2. Carrier Aggregation (CA) Environment

[88] 2.1 General CA

389. 3GPP LTE (3rd Generation Partnership Project Long Term Evolution; Rel-8 or Rel-9) system (hereinafter, LTE ^' system) is a multi-carrier that uses a single component carrier (CC) by dividing it into multiple bands. Multi-Carrier Modulation (MCM) is used. However, 3GPP LTE- Advanced systems (eg, Rel-10 or Rel-11; hereinafter, In LTE-A system, a method such as carrier aggregation (CA) may be used in which one or more component carriers are combined and used to support wider system bandwidth than the LTE system. Carrier aggregation may be replaced with the words carrier aggregation, carrier matching, multi-component carrier environment (Multi-CC) or multicarrier environment.

In the present invention, the multi-carrier means the aggregation of carriers (or carrier aggregation), wherein the aggregation of carriers means not only merging between contiguous carriers but also merging between non-contiguous carriers. . In addition, the number of component carriers aggregated between downlink and uplink may be set differently. The case where the number of downlink component carriers (hereinafter referred to as 'DL CC') and the number of uplink component carriers (hereinafter referred to as 'UL CC') is equal is called symmetric merging. It is called asymmetric merging.

Such carrier aggregation may be commonly used with terms such as carrier aggregation, bandwidth aggregation, spectrum aggregation, and the like. In LTE-A system, carrier aggregation, in which two or more component carriers are combined, aims to support up to 100 MHz bandwidth. When combining one or more carriers having a bandwidth smaller than the target band, the bandwidth of the combining carrier may be limited to the bandwidth used by the existing system to maintain backward compatibility with the existing IMT system.

For example, the existing 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHz bandwidth, and the 3GPP LTE-advanced system (ie, LTE-A) is not compatible with the existing system. In order to support the bandwidth larger than 20MHz by using only the above bandwidth. In addition, the carrier aggregation system used in the present invention may support carrier aggregation by defining a new bandwidth regardless of the bandwidth used in the existing system. In addition, the carrier aggregation may be divided into an intra-band CA and an inter-band CA. Intra-band carrier coalescing means that a plurality of DL CCs and / or UL CCs are located adjacent to or adjacent in frequency. In other words, it may mean that the carrier frequencies of the DL CCs and / or UL CCs are located in the same band. On the other hand, an environment far from the frequency domain may be referred to as an inter-band CA. In other words, it may mean that the carrier frequencies of the plurality of DL CCs and / or UL CCs are located in different bands. In this case, the terminal may use a plurality of radio frequency (RF) terminals to perform communication in a carrier aggregation environment.

[94] The LTE-A system uses the concept of a cell to manage radio resources. The aforementioned carrier aggregation environment may be referred to as a multiple cells environment. A cell is defined as a combination of a downlink resource (DL CC) and an uplink resource (UL CC), but the uplink resource is not an essential element. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources.

For example, when a specific UE has only one configured serving cell, it may have one DL CC and one UL CC, but when a specific UE has two or more configured serving cells. Has as many DL CCs as the number of cells and the number of UL CCs may be less than or equal to that. Or, conversely, DL CC and UL CC may be configured. That is, when a specific UE has a plurality of configured serving cells, a carrier aggregation environment in which a UL CC has more than the number of DL CCs may be supported.

In addition, carrier merge (CA) may be understood as a merge of two or more cells, each having a different carrier frequency (center frequency of the cell). Here, the term 'cell' should be distinguished from 'cell' as a geographic area covered by a commonly used base station. Hereinafter, the above-described intra-band carrier merging is referred to as intra-band multi-cell, and inter-band carrier merging is referred to as inter-band multi-cell. The cell used in the LTE-A system includes a primary cell (PCell) and a secondary cell (SCell). P cells and S cells can be used as a serving cell (Serving Cell). For RRC, but a _"CONNECTED state does not have a carrier is set or combined supporting carrier combined terminal, a serving cell configured only with the cell P is present only one. On the other hand, in case of a UE in RRC_CONNECTED state and carrier aggregation is configured, one or more serving cells may exist, and the entire serving cell includes a P cell and one or more s cells.

The serving cells (P cell and S cell) may be configured through an RRC parameter. PhysCellld is the cell's physical layer identifier and has an integer value from 0 to 503. SCelllndex is a short identifier used to identify an SCell and has an integer value from 1 to 7. ServCelllndex is a short identifier used to identify a serving cell (P cell or S cell) and has an integer value from 0 to 7. A value of zero applies to P cells, and SCelllndex is pre-assigned to apply to S cells. That is, the cell having the smallest cell ID (or cell index) in ServCelllndex becomes a P cell.

A P cell refers to a cell operating on a primary frequency (or primary CC). The UE may be used to perform an initial connection establishment process or to perform a connection re-establishment process and may also refer to a cell indicated in the handover process. In addition, the P cell refers to a cell serving as a center of control-related communication among serving cells configured in a carrier aggregation environment. That is, the UE can receive and transmit a PUCCH only in its P SAL and use only the P SAL to obtain system information or change a monitoring procedure. E-UTRAN (Evolved Universal Terrestrial Radio Access) changes only the Pcell for the handover procedure by using an RRC ConnectionReconfigutaion message of a higher layer including mobility control information to a UE supporting a carrier aggregation environment. It may be. A 1001 S cell may refer to a cell operating on a secondary frequency (or secondary CC). Only one P sal is allocated to a specific terminal, and more than one S sal may be allocated. The S cell is configurable after the RRC connection is established and may be used to provide additional radio resources. PUCCH does not exist in the remaining cells except the P cell, that is, the S cell, among the serving cells configured in the carrier aggregation environment.

When the E-UTRAN adds the S cell to the UE supporting the carrier aggregation environment, the E-UTRAN may provide all system information related to the operation of the related cell in the RRC_CONNECTED state through a dedicated signal. The change of the system information may be controlled by the release and addition of the related S cell, and at this time, an RRC connection reconfigutaion message of a higher layer may be used. The E-UTRAN may perform dedicated signaling having different parameters for each terminal, rather than broadcasting in the related S cell.

After the initial security activation process is started, the E-UTRAN may configure a network including one or more s cells in addition to the P cell initially configured in the connection establishment process. In a carrier aggregation environment, the P cell and the S cell can operate as respective component carriers. In the following embodiments, the primary component carrier (PCC) may be used in the same sense as the P cell, and the secondary component carrier (SCC) may be used in the same meaning as the SCell. [103] 2.2 Cross Carrier Scheduling

In a carrier aggregation system, there are two types of a self-scheduling method and a cross carrier scheduling method in terms of scheduling for a carrier (or carrier) or a serving cell. Cross carrier scheduling may be referred to as Cross Component Carrier Scheduling or Cross Cell Scheduling. [105] Self-scheduling is a UL in which a PDCCH (DL Grant) and a PDSCH are transmitted on the same DL CC, or a PUSCH transmitted according to a PDCCH (UL Grant) transmitted on a DL CC is linked to a DL CC that has received an UL Grant. Means to be transmitted through the CC.

In cross-carrier scheduling, a PDCCH (DL Grant) and a PDSCH are transmitted to different DL CCs, or a PUSCH transmitted according to a PDCCH (UL Grant) transmitted from a DL CC is linked to a DL CC having received an UL grant. This means that it is transmitted through a UL CC other than the UL CC.

Whether or not cross-carrier scheduling may be activated or deactivated UE-specifically and may be known for each UE semi-statically through higher layer signaling (eg, RRC signaling). .

When cross-carrier scheduling is activated, a carrier indicator field (CIF: Carrier Indicator Field) indicating a PDSCH / PUSCH indicated by the corresponding PDCCH is transmitted to the PDCCH. For example, the PDCCH may allocate PDSCH resource or PUSCH resource to one of a plurality of component carriers using CIF. That is, CIF is set when a PDSCH or PUSCH resource is allocated to one of DIJUL CCs in which a PDCCH on a DL CC is multi-aggregated. In this case, the DCI format of LTE Release-8 may be extended according to CIF. In this case, the configured CIF may be fixed as a 3 bit field or the position of the configured CIF may be fixed regardless of the DCI format size. In addition, the PDCCH structure (same coding and resource mapping based on the same CCE) of LTE Release-8 may be reused.

On the other hand, CIF is not configured when the PDCCH on the DL CC allocates PDSCH resources on the same DL CC or PUSCH resources on a single linked UL CC. In this case, the same PDCCH structure (same coding and resource mapping based on the same CCE) and DCI format as in LTE Release-8 may be used.

When cross-carrier scheduling is possible, the UE provides PDCCHs for a plurality of DCIs in the control region of the monitoring CC according to a transmission mode and / or bandwidth for each CC. It is necessary to monitor. Therefore, the structure of the search space that can support this

PDCCH monitoring is required.

In the carrier aggregation system, the terminal DL CC set represents a set of DL CCs scheduled for the terminal to receive a PDSCH, and the terminal UL CC set represents a set of UL CCs scheduled for the UE to transmit a PUSCH. In addition, the PDCCH monitoring set represents a set of at least one DL CC that performs PDCCH monitoring. The PDCCH monitoring set may be the same as the UE DL CC set or may be a subset of the UE DL CC set. The PDCCH monitoring set may include at least one of DL CCs in the terminal DL CC set. Alternatively, the PDCCH monitoring set may be defined separately regardless of the UE DL CC set. The DL CC included in the PDCCH monitoring set may be configured to always enable self-scheduling for the linked UL CC. The UE DL CC set, the UE UL CC set, and the PDCCH monitoring set may be configured UE-specifically, UE group-specifically, or cell-specifically.

When cross carrier scheduling is deactivated, it means that the PDCCH monitoring set is always the same as the UE DL CC set. In this case, an indication such as separate signaling for the PDCCH monitoring set is not necessary. However, when cross-carrier scheduling is activated, the PDCCH monitoring set is preferably defined in the terminal DL CC set. That is, in order to schedule the PDSCH or the PUSCH for the terminal, the base station transmits the PDCCH through only the PDCCH monitoring set.

FIG. 6 shows a subframe structure of an LTE-A system according to cross carrier scheduling used in embodiments of the present invention.

Referring to FIG. 6, three DL component carriers (DL CCs) are combined in a DL subframe for an LTE-A terminal, and DL CC 'A' is a PDCCH monitoring DL. The case is set to CC. If CIF is not used, each DL CC may transmit a PDCCH for scheduling its PDSCH without CIF. On the other hand, when the CIF is used through higher layer signaling, only one DL CC 'A' may transmit a PDCCH for scheduling its PDSCH or PDSCH of another CC using the CIF. At this time, DL CCs 'B' and 'C' that are not configured as PDCCH monitoring DL CCs do not transmit the PDCCH.

[115] 3. FDR system

The FDR system can be applied to the LTE / LTE-A system described above. That is, the frame structure defined in the LTE / LTE-A system, the control signal transmission / reception method, and the support for the carrier coupling scheme may all be applied to the FDR system.

An FDR means a system that simultaneously supports data transmission and reception using the same resource (that is, the same time and the same frequency) in one UE. FDR may be a new type of wireless access system. However, in the embodiments of the present invention, it is assumed that the FDR system operates based on the LTE / LTE-A system described with reference to FIGS. 1 to 6.

[118] 3.1 General FDR System

7 is a layout diagram illustrating an example of a wireless access system that supports FDR.

Referring to FIG. 7, a radio access system supporting FDR includes a macro base station (eNB) managing a normal cell, a small base station managing a small cell, and a terminal (ie, a wireless unit). In this case, the small base station includes a micro base station (micro eNB), a femto base station (Femto eNB) and a pico base station (Pico eNB).

In the situation as shown in FIG. 7, three types of interference may exist.

[122] (1) Intra-Device Interference (IDI) IDI means that a signal transmitted from a transmitting antenna of a base station or a terminal is received by the receiving antenna and acts as an interference due to the FDR characteristic. The signal transmitted from the transmission antenna of the specific device is transmitted with a greater power than the signal to receive. This is because the signal transmitted from the transmitting antenna is received by the receiving antenna with little attenuation since the distance between the transmitting antenna and the receiving antenna of the specific device is short. Therefore, the transmission signal transmitted by the transmission antenna of the specific device is received with a power much greater than the desired signal (desired signal) that the specific device expects to receive from the other party.

[124] (2) UE to UE Inter-link Interference

The link interference between terminals means that an uplink signal transmitted by a specific terminal is received by another terminal located adjacent to act as interference.

[126] (3) BS to BS Inter-link Interference

Link interference between base stations means that signals transmitted between heterogeneous base stations between base stations or HetNet situations are received by receiving antennas of other base stations and act as interference.

Among these three interferences, the magnetic interference in the device (hereinafter, magnetic interference) is the first problem to be solved in order to operate the FDR due to the influence of the interference occurring only in the FDR.

8 is a diagram illustrating a concept of self-interference in an FDR system.

Although FIG. 8 illustrates a case in which data communication is performed between terminals for convenience of description, the same applies to data communication between a terminal and a base station.

Referring to FIG. 8, in a FDR environment, a transmission signal transmitted by a transmission antenna of a first terminal UE1 to a second terminal UE2 is received by a reception antenna of a first terminal to serve as an interference signal. This self-interference is unique unlike other interferences. First, the first terminal can be regarded as a signal that perfectly knows the interference signal acting as interference. This is because the self-interference signal coming into the reception antenna of the first terminal is a transmission signal transmitted by the first terminal.

[133] The second is that the power of the interference signal acting as interference is much higher than the power of the preferred signal that the first terminal is to receive. This is because the distance between the transmitting antenna and the receiving antenna of the first terminal is very small compared to the distance between the first terminal and the second terminal. This is a factor that can not completely remove the interference signal from the receiving antenna of the terminal even if the terminal completely knows the signal acting as interference.

In the receiving antenna of the terminal, an analog to digital converter (ADC) may be used to convert the received signal into a digital signal. In general, the ADC measures the power of a received signal, adjusts the power level of the received signal, and then quantizes it to convert it into a digital signal. However, since the interference signal is received at a much higher power than the desired signal, the signal characteristic of the preferred signal may be buried at the quantization level and may not be restored.

FDR is a technology that can improve the capacity of the system compared to the existing half-duplex communication by simultaneously transmitting and receiving at one node. FDR suffers from strong self-interference due to its simultaneous transmission and reception over the same resource. Early studies have shown performance under completely canceled magnetic interference, assuming complete channel state information (CSI).

However, in an actual wireless communication system, there is a channel estimation error, which makes it difficult to obtain complete channel information. This uncertain channel information is a cause of the complete elimination of magnetic interference in the conventional scheme. In this situation, methods for eliminating magnetic interference have been proposed and implemented in software and hardware to improve the performance of the FDR. The magnetic interference cancellation technology studied so far is largely Passive self-interference cancellation and active self-interference cancellation can be distinguished.

Hereinafter, a specific interference cancellation method occurring in the FDR system will be described in detail.

[138] 3.1 Elimination of Interference in FDR Systems

The passive magnetic interference cancellation method uses an antenna to reduce magnetic interference, and thus, the best combination of the magnetic interference cancellation performance can be found by a method of various combinations of positions of a transmitting antenna and a receiving antenna. The concern about the antenna position is to maximize the path loss of the magnetic interference channel and to reduce the line of sight (LOS) component. Thus, the performance of passive interference cancellation depends on the distance between the antennas, the direction of the antennas, and the FDR device on which the antenna is mounted. As a result, magnetic interference cancellation performance of about 65dB was obtained in the environment where the receiving antenna is located perpendicular to the transmitting antenna.

If the passive interference elimination scheme is applied to the communication infrastructure other than the user terminal, there is an advantage that a wider space can be utilized. Therefore, RF absorbers, cross polarization, and directional antennas, which are difficult to use in a user terminal, can be applied, and when the three methods operate simultaneously, a performance of about 95 dB can be obtained.

In addition, a method of using a single transmission antenna in a terminal to locate at a half wavelength distance in consideration of a communication frequency so that signals of two transmission antennas cancel each other's signals is also studied. However, there is a disadvantage that the correct position and frequency must be matched and the offset effect only occurs for the center frequency component.

[142] The active interference cancellation scheme is further divided into analog cancellation scheme and digital cancellation scheme. In the case of the analog cancellation method, the reception signal operates in the analog domain before the received signal passes through the analog-to-digital converter (ADC). Considering the application of the passive interference cancellation scheme in a node to which OFDM MIMO is applied, the magnetic interference reception signal of the k-th subcarrier coming into the antenna _n of node i may be expressed by Equation 1 below.

[144] [Equation 1]

Here, denotes a signal transmitted from antenna m of node i to k-th subcarrier. In this case, the node i may be a terminal. The analog interference cancellation scheme is implemented to remove magnetic interference by subtracting the estimated ^{y [fe]} value from the received signal coming into the nth antenna. A signal connected to the reception antenna n of the terminal to remove the k-th subcarrier signal may be expressed by Equation 2 below.

[146] [Equation 2]

In Equation 2, ^] represents the magnitude and phase of the k-th subcarrier signal to the antenna n of the node i is affected by the wire characteristics inside the circuit. And [denotes a cancellation coefficient of the k-th subcarrier signal to antenna _m of node i. Using this definition, the magnetic interference of the k-th subcarrier signal coming into antenna n after analog interference cancellation is represented by the following equation.

[148] [Equation 3] m = l

[149] Referring to Equation 3, values of m and _n [ ^k may be satisfied for perfect magnetic interference cancellation. However, the value of ^h ', m value / _k] in the system is not known exactly and uses the estimated value obtained through channel estimation. This estimate is close to the actual value, allowing accurate magnetic interference cancellation and residual self-interference approaching zero. Once this rejection coefficient is determined, a signal is generated through the analog circuitry and added to the received signal coming into the receive antenna. In this regard, published papers (M. Jainy, JI Choi, TM Kim, D. Bharadia, S. Seth _: K. Srinivasan, P. Levis, S. Katti, P. Sinha, "Practical, Real-time, Full Duplex) Wireless, "Mobicom 2011, Nov. 2010." For example, the self-interference cancellation is implemented by adding a signal going to the transmitting antenna of the terminal to an inverted signal through the Balun circuit and correcting the attenuation and delay values calculated therein, and adding the signal to the receiving antenna of the terminal.

[150] In the case of digital interference cancellation, a technique for removing residual magnetic interference remaining after analog interference cancellation. Conceptually, the residual magnetic interference is estimated and its value is removed from the received signal in the digital domain. ^In order to estimate ^y '-" ^[k] , after the analog interference cancellation is applied to each antenna, the pilot signal is transmitted again to estimate the residual magnetic interference of each antenna.

[151] The system using the analog interference cancellation method operates as follows.

(1) First, the terminal periodically estimates each channel through a pilot signal.

(2) When the UE estimates the channel, the UE estimates the magnetic interference channel and the channel through which the signal is transmitted from the base station. At this time, the removal coefficient according to the channel value

⁶ ', "] is determined. W denotes the magnitude and phase of the _k- th subcarrier signal going to the antenna _n of the i-th terminal (that is, the node i) is affected by the wire characteristics inside the circuit.

A system using the digital interference cancellation method operates as follows.

[1] (1) First, all the processes of analog interference cancellation are performed. If you do not use analog interference cancellation, perform manual interference cancellation.

[2] To estimate the residual self-interference remaining after (2), This process works by first applying the interference cancellation scheme to each antenna and then sending a pilot signal to estimate the residual magnetic interference of each antenna.

However, the above-described self-interference cancellation techniques can completely remove the magnetic interference only if the channel information is accurate. Therefore, many performance decreases may occur due to channel estimation errors occurring during channel estimation in a real environment. For example, an error occurs in each value of and due to the channel estimation error, which generates an incomplete rejection factor ⁶ '. "[], Which may result in residual magnetic interference.

Therefore, the following describes a self-interference cancellation method that can reduce the performance decrease caused by the channel estimation error in the real environment.

[159] 3.2 Magnetic Interference Cancellation Using Rotating Precoder

For an example of the FDR system used in the embodiments of the present invention, see FIG. 8. In this case, a channel through which an interference signal is transmitted is defined as h _SI and a channel through which a preferred signal is transmitted is defined as ^. . In addition, it is assumed that the second terminal is a base station.

For example, assuming that two antennas exist in a base station, the antenna of the base station completely eliminates magnetic interference between the transmitting antenna and the receiving antenna through a signal isolating technique and a powerful passive interference technique. This assumes an environment in which full-duplex communication can be used. The active interference cancellation method described in Section 3.1 operates by canceling an interference signal from a received signal by calculating a cancellation coefficient based on channel information obtained through channel estimation in the terminal.

On the other hand, Rotated Precoder Based Self-Interference Cancellation (RP-SIC) of the present invention is performed so that the self-interference channel ^hsi is perpendicular to the detection direction of the preferred signal. Interference can be eliminated by rotating the magnetic interference channel using a coder. 9 is a diagram illustrating an example of a method of rotating a magnetic interference channel through RP-SCI.

Referring to FIG. 9, the channel information on the actual self-interference channel obtained by the terminal may be as including a channel estimation error. In the present invention, self-interference can be eliminated using a including a real channel estimation error. That is, the terminal can obtain an angle ^ that makes the estimated channel including the direction of detection of the preferred signal and the actual error vertical. If you feed back this value to the precoder ^, the value of ^ is determined to reflect ^. Hereinafter, for convenience of description, the actual self-interference channel ^h s' is described, but the object of the present invention can be achieved even by using the estimated channel.

[165] Meanwhile, the concept of RP-SIC is to rotate the self-interference channel ^h s' so that the preferred signal is perpendicular to the detection axis where the detection signal is detected. Therefore, interference is too large for the axis of Z, which is a rotated magnetic interference channel, so that the receiving end cannot detect it. The RP-SIC consumes one dimension in a two-dimensional signal space of a received signal in order to remove magnetic interference.

Accordingly, as shown in FIG. 10, a method of detecting a QAM symbol using one detection axis using a rotated quadrature amplitude modulation (QAM) signal may be applied. FIG. 10 is a diagram illustrating an example of a method of detecting each symbol with a detection axis using quadrature phase shift keying (QPSK) symbols. In FIG. 10, a black dot represents a reception symbol mapped on the constellation, ^ represents a rotated self-interference channel, and ^h s' represents a self-interference channel. In this case, when using the rotated QAM symbol in FIG. 10, the angle 0 is a specific angle formed by ^, which is the real axis and the rotated magnetic interference channel, and this angle may be determined so that the projected QAM symbols are equally spaced apart. In this case, the precoder ^ and the rotation angle are expressed as in Equation 4 below.

[168] [Equation 4]

W = cos 6 _w + i-sin Θ _ψ ，

θ _ψ ^ Θ-Θ _Μ ,

In Equation 4, denotes an angle that the terminal already knows, and is an angle formed by the magnetic interference channel ^h s' and the real axis. The reference real axis is determined from the preferred channel. That is, the detection axis is determined based on the real axis in which the preferred channel is detected. For example, when projecting symbols mapped to constellations based on the real axis to one axis, an axis in which the intervals of the projected symbols are equally spaced may be determined as the detection axis. As described above, it is difficult to obtain complete channel information in a real environment. For this reason, the performance of RP-SICs tends to be reduced by angular errors, which requires additional operation to reduce these angular errors. The rotation angle of the precoder operates to receive and update the information on the angle error. Since the self-interference channel is an environment in which the channel environment between the transmitter and the receiver is fixed, assume a slow fading situation in which the self-interference channel does not change rapidly. Accordingly, the terminal may estimate the angle at which the detection axis and the estimated self-interference channel are vertical through iterative feedback. In this case, the error angle ^θ is given by Equation 5 below.

[172] [Equation 5]

Referring to FIG. 9, ^S s' means a value projecting ^Wh s! Toward the detection axis. In this case, when a large error component occurs due to the random nature of the self-interfering channel, a value entering the sin inverse function may be greater than 1 or less than -1. In this case, the result of the inverse sin function has a large error.

Therefore, before performing the sin inverse function, it is confirmed that the input value is smaller than the absolute value 1, and if the value is larger than this value, the error is large in the channel estimation.

The RP-SIC method gives a condition when performing repetitive feedback and estimates a channel again until it satisfies it. However, it is necessary to set the repetition of the estimation up to n times in case the power of the channel is very small instantaneously and the repetition of several times does not satisfy this range. In this case, the maximum number of repetitions _n can be appropriately determined according to the environment of the system.

[176] If an attempt is made until the maximum number of iterations is n, the desired value is needed. In this situation, the terminal applies m predefined angle samples and feeds back the best performing angle to the base station. For example, if m is 5, the receiver creates a precoding matrix W for -72 degrees, -36 degrees, 0 degrees, 36 degrees, and 72 degrees, and selects the best performing W.

In addition, when additionally repeating the channel estimation by the maximum number of repetitions, other values are changed, but since information on the estimated channel amplitude is continuously accumulated, it is necessary to use this information efficiently. In embodiments of the present invention, a more accurate value can be obtained by designing to take and use an average value of the estimated channel amplitude through information obtained by repeating channel estimation.

The above is summarized. Initially, the terminal receives a pilot signal (or reference signal) from the base station to obtain preferred channel information. Next, the transmitter of the terminal generates a pilot signal to obtain information on the magnetic interference channel. The terminal is such Based on the information, the angle to rotate through the precoder is obtained and transmitted to the precoder of the terminal. The terminal generates a pilot signal once again when the precoder configured based on the information on the rotation angle operates, and the receiver of the terminal measures the amount of residual magnetic interference. Based on this value, the angle of rotation is recalculated and this value is reflected to the precoder through feedback. By repeating this process, the angle error can be reduced.

FIG. 11 is a diagram summarizing an example of a method of eliminating interference based on a rotating precoder in a terminal.

A signal transmitted from the terminal to the base station is defined as an interference signal, and a signal transmitted from the base station to the terminal is defined as a preferred signal.

In this case, the terminal may estimate the preferred channel by receiving the first reference signal transmitted from the base station. In addition, the terminal may estimate the interference channel by receiving the second reference signal transmitted by the terminal. In this case, the second reference signal may be a dedicated reference signal transmitted for the purpose of self-interference cancellation (S1 110 and S1 120).

The terminal may specify the detection axis of the preferred channel based on the preference signal and / or the first reference signal. Thereafter, the terminal calculates a first angle 0 (angle from the real axis) that is 90 degrees from the detection axis. In addition, the terminal may obtain the rotation angle by subtracting the second angle ^θ '"for the known interference channel from the first angle ^ (S1130).

In addition, the UE may be closer to the angle at which the detection axis and the estimated interference channel are perpendicular through repetitive feedback on the angle error. That is, the first rotation angle is also obtained by obtaining an angle at which the detection axis and the estimated interference channel are perpendicular to each other. However, there may be an error since this is also a result of the terminal estimation. Therefore, the terminal may transmit and receive the second reference signal again to feed back information about the angle error (S1140). The terminal may compensate for the rotation angle based on the information about the feedback angle error. Thereafter, the UE can obtain the compensated self-interference channel Wh ' _SI ^ by rotating the interference channel in a precoding matrix having a rotation angle (S1 150).

The terminal may remove the interference signal by projecting the received interference signal and the preferred signal on the detection axis.

[186] 3.3 RP-SIC Performance

12 is a diagram illustrating average processing performance of a terminal according to embodiments of the present invention according to a channel estimation error. In order to verify the performance of the proposed RP-SIC scheme, Monte Carlo simulation was performed while varying the variance of the channel estimation error ° ^"£ . To compare the performance of the RP-SIC scheme, A self-interference cancellation (SIC) technique in which a channel is estimated using a conventional technique and subtracted from a received signal is used as a control group [189] FIG. The graph shows the repetitive feedback for each of the existing SIC and RP-SIC techniques.

Comparing the technique between 1 and 2 performances, the SIR values representing the magnitude of the magnetic interference show -20dB and -50dB. First, in the case of -50dB where the magnitude of magnetic interference is relatively high, the RP-SIC technique shows better performance than the conventional SIC technique in all regions.

This is the result of the interference cancellation performance of the proposed RP-SIC method better than the existing SIC method in the environment where the interference cancellation ability greatly affects the performance of the user due to the large amount of magnetic interference. On the other hand, in a -20dB environment where the amount of magnetic interference is relatively small, there is an area where the conventional SIC technique performs better than the RP-SIC technique in a region where the channel estimation error is small. In environments where the channel estimation error is small and the amount of magnetic interference is about 20 dB smaller than the desired signal, Even the SIC technique can achieve the effect of eliminating self-interference. In the case of the RP-SIC technique, this reversal interval occurs due to the performance loss due to the reduction of the signal size caused by the projection of the rotated QAM symbol to detect the signal using the detection axis.

[191] Finally, for each technique, the performance degradation that decreases as the magnitude of the magnetic interference increases. It can be seen that the RP-SIC technique has a significantly smaller performance drop compared to the conventional technique. These results show that the proposed scheme has stronger characteristics for magnetic interference than the existing scheme, and shows better performance in the environment where the channel estimation is not accurate and the magnitude of magnetic interference is large.

FIG. 13 is a diagram illustrating performance when a 12-bit ADC is used without modeling channel estimation errors as random variables through variance. Compared to the case of analyzing the channel estimation error with a random variable, the performance is measured by using a 12-bit ADC and the performance is decreased while the larger error occurs during angle calculation and channel estimation. Compared to the better performance.

[193] 4. Implementation device

The apparatus described with reference to FIG. 14 is a means in which the methods described with reference to FIGS. 1 through 1 may be implemented.

A UE may operate as a transmitting end in uplink and a receiving end in downlink. In addition, an e-Node B (eNB) may operate as a receiving end in uplink and a transmitting end in downlink.

That is, the terminal and the base station may include a transmitter (1440, 1450) and a receiver (receiver: 1450, 1470) to control the transmission and reception of information, data and / or messages, respectively, the information, Or one or more antennas 1400 and 1410 for transmitting and receiving data and / or messages. In FIG. 14, the transmitter and the receiver are shown to share an antenna, but as shown in FIG. 8, separate antennas may be provided in the transmitter and the receiver. In addition, although three antennas are illustrated in each device in FIG. 14, a plurality of antennas may be provided instead of three.

In addition, the terminal and the base station each of the processor (Processor 1420, 1430) for performing the above-described embodiments of the present invention and the memory (1480, 1490) that can temporarily or continuously store the processing of the processor Each may include.

Embodiments of the present invention can be performed using the components and functions of the above-described terminal and base station apparatus. For example, the processor of the base station or the terminal may estimate and remove the self-interfering channel using the RP-SIC method by combining the methods described in Sections 1 to 3 described above. In addition, the processor may include a precoder for the RP-SIC scheme. Of course, the precoder may be configured in the terminal separately from the processor.

The transmission modules and the reception module included in the terminal and the base station include a packet modulation and demodulation function, a high speed packet channel coding function, an orthogonal frequency division multiple access (OFDMA) packet scheduling, and a time division duplex Time Division Duplex (TDD) packet scheduling and / or channel multiplexing may be performed. In addition, the UE and the base station of FIG. 14 may further include low power radio frequency (RF) / intermediate frequency (IF) models. In this case, the transmitting module and the receiving module may be called a transmitter receiver, respectively, and may be called a transceiver when used together.

Meanwhile, in the present invention, the terminal is a personal digital assistant (PDA), a cell phone, a personal communication service (PCS) phone, a GSM (Global System for Mobile) phone, a WCDMA (Wideband CDMA). A phone, a mobile broadband system (MBS) phone, a hand-held PC, a notebook PC, a smart phone, or a multi-mode multi-band (MM-MB) terminal can be used. have. Here, a smartphone is a terminal that combines the advantages of a mobile communication terminal and a personal portable terminal, and includes a terminal integrating a data communication function such as schedule management, fax transmission and reception, which are functions of a personal portable terminal, in a mobile communication terminal. Can mean. In addition, a multimode multiband terminal has a built-in multi-mortem chip that can operate in both portable Internet systems and other mobile communication systems (e.g., code division multiple access (CDMA) 2000 systems, wideband CDMA (WCDMA) systems, etc.). Speak the terminal.

Embodiments of the present invention may be implemented through various means. For example, embodiments of the present invention may be implemented by ^one such hardware, firmware (firmware), software, or a combination thereof.

In the case of implementation by hardware, the method according to the embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), and programmable PLDs. logic devices), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of modules, procedures, or functions that perform the functions or operations described above. For example, the software code may be stored in the memory units 1480 and 1490 and driven by the processors 1420 and 1430. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. Also, in the claims Embodiments may be constructed by combining claims that do not have an explicit citation or may be incorporated into new claims by post-application correction.

Industrial Applicability

Embodiments of the present invention can be applied to various wireless access systems. Examples of various radio access systems include 3rd Generation Partnership Project (3GPP), 3GPP2 and / or IEEE 802.XX (Institute of Electrical and Electronic Engineers 802) systems. Embodiments of the present invention can be applied not only to the various radio access systems, but also to all technical fields that use the various radio access systems.

Claims

【Scope of Claim】

【Claim 11

In a method for a terminal to remove rotation precoder-based self-interference in a wireless access system supporting full duplex radio (FDR),

Receiving a first reference signal from a base station;

Receiving, by the terminal, a second reference signal transmitted from the terminal;

estimating a preferred channel based on the first reference signal and estimating a self-interference channel based on the second reference signal;

measuring a rotation angle based on a first angle perpendicular to the detection axis for the preferred channel and a second angle for the interference channel;

rotating the self-interference channel using the rotation angle; And removing the interference signal based on the rotated self-interference channel,

The first angle and the second angle are values measured from the angle 0 of the real axis.

【Claim 2】

According to clause 1,

retransmitting the second reference signal;

acquiring information about the error angle using the retransmitted second reference signal; and

Self-interference removal method further comprising compensating the rotation angle based on information about the error angle.

[Claim 3]

In paragraph 2,

A self-interference removal method in which the remaining steps, except for the step of removing the interference signal, are repeated a predetermined number of times.

【Claim 4】

The method of claim 2, wherein the error angle ^θ > is calculated as follows,

[Equation]

^Ss 'means a value projected from the rotated self-interference channel toward the detection axis, and _11'31 means the estimated self-interference channel. A self-interference removal method.

【Claim 5】

In clause 1,

The first angle is the angle between the real axis and the rotated self-interference channel,

A self-interference removal method in which the symbols projected onto the detection axis are at equal intervals.

【Claim 6】

A terminal for removing rotation precoder-based self-interference in a wireless access system supporting full duplex radio (FDR) method,

transmitter;

receiving set;

A processor for controlling the transmitter and the receiver to support removal of magnetic interference based on the rotation precoder,

The processor:

Controlling the receiver to receive a first reference signal from a base station;

Controlling the receiver to receive a second reference signal transmitted from the transmitter;

measure a rotation angle based on a first angle perpendicular to the detection axis for the preferred channel and a second angle for the interference channel;

rotating the self-interference channel using the rotation angle;

A terminal configured to remove an interference signal based on the rotated self-interference channel, wherein the first angle and the second angle are values measured from angle 0 of the real axis.

【Claim 7】

According to clause 6, The processor:

Control the transmitter to retransmit the second reference signal;

Obtain information about an error angle by controlling the receiver to receive the retransmitted second reference signal; and

The terminal is further configured to compensate for the rotation angle based on information about the error angle.

【Claim 8】

According to clause 7,

A terminal in which the processor repeatedly performs an interference cancellation operation a predetermined number of times.

【Claim 9】

According to clause 7,

The error angle ^ is calculated as follows,

[Equation]

= ^—' (| |/|¾ |), Ss' refers to a value projected from the rotated self-interference channel toward the detection axis, and 11' ₅₁ refers to the estimated self-interference channel, terminal.

【Claim 10】

According to clause 6,

The first angle is the angle formed by the real axis and the rotated self-interference channel,

A terminal at which the symbols projected onto the detection axis are at equal intervals.