WO2016163658A1

WO2016163658A1 - Unlicensed band lte data interference signal detection and decoding method

Info

Publication number: WO2016163658A1
Application number: PCT/KR2016/002596
Authority: WO
Inventors: 엄중선; 유성진; 정회윤; 박승근
Original assignee: 한국전자통신연구원
Priority date: 2015-04-09
Filing date: 2016-03-15
Publication date: 2016-10-13

Abstract

The present invention relates to a signal processing method in a spectrum sharing wireless communication system wherein, in an environment where, among UEs included in a licensed band (e.g., LTE) network, licensed band (e.g., LTE) data is transmitted/received by using an unlicensed band (e.g., WiFi), a zero powered resource element (ZPRE) pattern and an allocation method are proposed, and the existence or not of an unlicensed band (e.g., WiFi) interference signal is identified by using the ZPRE, and the interference strength, the number of licensed band (e.g., LTE) symbols affected by the interference are confirmed and processed, and thus a high interference signal impact by means of a short unlicensed band (e.g., WiFi) signal transmitted by an unlicensed band (e.g., WiFi) device adjacent to a UE is minimized, and decoding is made possible in order to enhance reception performance in an interference environment.

Description

Interference signal detection and decoding method of unlicensed band data

The present invention relates to a frequency common use wireless communication system in which a licensed band (e.g., LTE) system coexists with an unlicensed band system in an unlicensed band (e.g., WiFi) and jointly uses the unlicensed band. For example, unlicensed band LTE data used in the LTE system can detect interference signals by signals from the unlicensed band system, and can be decoded to improve reception performance in an interference environment. It is about a method.

LTE (Long Term Evolution) based mobile communication system has evolved into high-speed packet data communication to provide data services such as multimedia services such as internet and video stream, away from voice-oriented services. To this end, 3GPP has evolved the standard technology to LTE-A, which aggregates up to five carriers (CA, Carrier Aggregation) in LTE systems that used to provide services to cells using up to 20MHz bandwidth.

1 is a diagram illustrating an access network of a network architecture of a general LTE / LTE-A. LTE-based mobile communication system may be composed of a macro cell (macro cell) for accessing the core network through the base station (eNB), and a small cell using the relay of the small cell base station in the macro cell, the terminal (UE) can receive data from the eNB of each cell. The link connected to the UE in each cell may be one channel or five channels may be CA.

2 is a diagram illustrating a frame structure of a general LTE / LTE-A. In a time domain view, 10 subframes constitute one radio frame for 10 msec, and one subframe consists of two slots. Each slot is composed of a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols. Seven slots are used per slot when N_CP (Normal Cyclic Prefix) is used and six slots are used when Extended Cyclic Prefix (CP) is used. 2 shows an example of N_CP, and 14 symbols constitute one subframe. In terms of frequency domain, 12 subcarriers constitute one resource block (RB), and the number of RBs uses a value defined in the standard by the system bandwidth.

Recently, 3GPP is developing a standard technology for utilizing the LTE system operating in the licensed band in the unlicensed band of 5GHz. Scenarios for aggregating and operating carriers in the licensed and unlicensed bands are considered first. The duplex of the unlicensed band is a TDD (Frequency Division Duplex (FDD) mode in downlink or TDD considering both uplink and downlink links). Consider Time Division Duplex mode. 3GPP names standard items Licensed Assisted Access (LAA) in terms of offloading licensed band data based on CA. In the 5GHz unlicensed band, since WiFi (Wireless Fidelity) is a commercial service, technology for coexisting with WiFi is required.

3 is a diagram illustrating an example in which a general LTE and WiFi network operate by using the same channel in an adjacent location. Channel access by WiFi accesses the channel after checking channel occupancy status using the conventional CSMA / CA (Carrier Sense Multiple Access) / (Collion Avoid) method, and the channel access by LTE does not have such a function. Channels should be accessed in such a way as to ensure fair channel usage with WiFi, such as List-before-Talk (LBT). However, in the case of WiFi, if a non-WiFi signal of -62dBm or less is detected, the WiFi wireless device transmits a signal, thereby interfering with an LTE-U (LTE in Unlicensed Band) signal.

4 is an exemplary diagram of a scenario for LTE signal interference by a general WiFi signal. Carrier sensing / Back-off (CS / BO) result for downlink of LTE-U LTE NB (Node B) transmits data while there is no WiFi signal, and this signal is WiFi Access Point (AP) If the receiver receives less than -62dBm, the WiFi AP also transmits data (Tx, Transmission). In this case, the UE generates interference by the WiFi signal from the WiFi AP during the reception of the LTE signal (Rx, Reception) from the LTE NB. In particular, when the WiFi AP is far from the NB but close to the UE, the strength of the interference signal becomes very large.

In the LTE standard, various types of reference signals (RSs) are transmitted to estimate downlink channel estimation or channel state. FIG. 5 is an exemplary diagram showing the location of an RE to which reference signals (RSs) can be transmitted in an RB in a typical LTE downlink. The CRS (Cell Specific Reference Signal, or Common Reference Signal) is used for channel estimation for coherent decoding of all downlink physical channels except PDSCH (Physical Downlink Shared Channel) using transmission modes 7, 8, and 9. The demodulation reference signal (DMRS) is used for channel estimation for PDSCH using transmission modes 7,8, 9, and 10 as a signal specific to each terminal. Channel State Information-Reference Signal (CSI-RS) is used so that the UE can acquire Channel State Information (CSI) when DMRS is used for channel estimation. The CSI-RS is not transmitted in every subframe, but at a very low time / frequency density. The control channel (CC) for the control signal transmission and the PDSCH for the shared channel transmission are arranged at the positions of the remaining REs. In addition, a multimedia broadcast multicast service single frequency network (MBSFN) RS used before a multicast channel (MCH) and a positioning RS (PRS) used for position estimation may be configured in downlink.

The UE of the LTE network measures downlink channel estimation or channel state based on the above signals and feeds them back to the NB, thereby enabling the NB to manage resources according to channel conditions. In this case, the UE acquires channel quality indicator (CQI) information with a value such as RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) using reference signals of CRS or CSI-RS that can be allocated as shown in FIG. 6.

However, since CRS or CSI-RS used for channel state estimation is not allocated to every symbol, it may not be detected when a WiFi signal exists as an interference source. In addition, the existing channel state estimation method uses RSRP or RSRQ of average signal strength, making it difficult to detect the instantaneous WiFi signal.

Another method for channel state estimation is to utilize CSI-IM. The LTE standard includes CSI-IM (Interference Measurement), which transmits one or several subsets of CSI-RS to Zero-power CSI-RS to accurately estimate CoMP (Coordinated Multi-Point) operation and inter-cell interference. It is defined. However, CSI-IM also has a limitation in measuring interference signals at every OFDM symbol since CSI-RS is transmitted with different periods within a range of at least 5ms to 80ms.

Accordingly, the present invention has been made to solve the above-described problem, an object of the present invention is to use a licensed band (eg, using a license-free band (eg, WiFi) of the UEs belonging to the licensed band (eg, LTE) network In the environment of transmitting / receiving LTE data, we present a Zero-Powered Resource Element (ZPRE) pattern and an allocation method, and determine the presence or absence of an unlicensed band (eg WiFi) interference signal using ZPRE. By identifying and processing the number of affected licensed band (e.g., LTE) symbols, it minimizes the impact of high interference signals caused by short unlicensed (e.g., WiFi) signals transmitted by unlicensed band (e.g. WiFi) devices adjacent to the UE. In addition, the present invention provides a signal processing method in a common frequency wireless communication system to enable decoding to improve reception performance in an interference environment.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following descriptions.

First, to summarize the features of the present invention, a signal processing method for coexisting with the unlicensed band system in the wireless communication system using a licensed band according to an aspect of the present invention for achieving the above object to use the unlicensed band as a secondary In the licensed band first system, some resource elements RE of at least one resource block RB constituting the data frame of the licensed band are allocated as zero power resource elements ZPRE, and the data frame including the ZPRE is unlicensed. Transmitting using the band; And receiving the data frame in a licensed band second system, measuring the strength of an unlicensed band interference signal in the ZPRE period, and performing channel decoding.

The ZPRE is a total of predetermined REs in which a downlink physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) of an uplink is disposed. Or some REs.

In this case, the ZPRE may be allocated to an RE of all subcarrier regions of one of the predetermined REs. The ZPRE may be assigned to one or more REs in each of two or more subcarrier regions of the predetermined REs. The ZPRE may be allocated to all REs of a subcarrier region in which a reference signal exists among the predetermined REs, and may be allocated to an RE adjacent to an up or down relative to the RE in which the reference signal exists.

The ZPRE is a predetermined number of M (natural numbers) at the symbol index (i) according to the equation "ZPRE_Index (i, k) = (Q (i) mod G + P (k) mode G) + (G * k)" ZPRE may be assigned to the subcarrier position ZPRE_Index (i, k) of the z-th ZPRE, where G is a period in which ZPRE is assigned, and Q (i) is determined by a symbol index (i) or randomly determined in a random permutation. The zero or positive integer, P (k), may be zero or a positive integer determined by the ZPRE position k at the symbol index i or arbitrarily determined in a random permutation.

The ZPRE may be allocated to one RE or a plurality of REs of the predetermined REs in each of a plurality of consecutive RBs.

The location on the subcarrier to which the ZPRE is allocated may be notified to the counterpart system by using downlink control information (DCI) of the PDCCH or by using another predetermined message or indication signal.

Confirming the number of REs that can transmit the actual data except for the location on the subcarrier to which the ZPRE is allocated in the licensed band 2 system and transmitting data to be transmitted according to a corresponding modulation scheme

Measuring the strength of the interference signal and performing channel decoding may include calculating the number of licensed band symbols affected by the interference signal and performing channel decoding based on the strength of the interference signal and the number of symbols. Determining a step.

Measuring the strength of the interference signal and performing channel decoding may include determining whether to perform channel decoding by receiving a hybrid automatic repeat and request (HARQ) response and combining a retransmitted signal with a signal received before the HARQ. It further comprises a step.

According to a signal processing method in a common frequency wireless communication system according to the present invention, licensed band (eg, LTE) data is transmitted using unlicensed band (eg, WiFi) among UEs belonging to a licensed band (eg, LTE) network. In the environment of transmitting and receiving, according to the Zero-powered Resource Element (ZPRE) pattern and the allocation method, it is possible to check the interference section by detecting a short unlicensed band (eg WiFi) interference signal using ZPRE, The number of affected licensed band (eg, LTE) symbols can be identified and processed.

Accordingly, it is possible to minimize the effect of high interference signals caused by short unlicensed band (eg WiFi) signals transmitted by unlicensed band (eg WiFi) devices adjacent to the UE, and decoding may be performed to improve reception performance in an interference environment. It is possible to improve decoding performance by combining the previously received signal with the retransmission signal via HARQ.

1 is a diagram illustrating an access network of a network architecture of a general LTE / LTE-A.

2 is a diagram illustrating a frame structure of a general LTE / LTE-A.

3 is a diagram illustrating an example in which a general LTE and WiFi network operate by using the same channel in an adjacent location.

4 is an exemplary diagram of a scenario for LTE signal interference by a general WiFi signal.

FIG. 5 is an exemplary diagram showing the location of an RE to which reference signals (RSs) can be transmitted in an RB in a typical LTE downlink.

6 is an exemplary diagram of reference signals (CRS, CSI-RS) that can be allocated in a general LTE downlink.

7 is a view for explaining an environment of a frequency shared wireless communication system according to an embodiment of the present invention.

8 illustrates an example in which all subcarrier regions of one of REs in which a PDSCH is arranged are allocated to ZPRE in the frequency coexistence wireless communication system according to the present invention.

FIG. 9 illustrates an example in which ZPRE is distributedly allocated to a plurality of subcarrier regions among REs in which PDSCHs are arranged in the frequency coexistence wireless communication system according to the present invention.

FIG. 10 illustrates an example in which ZPRE is allocated to two adjacent subcarrier regions while avoiding other reference signals RS among REs in which PDSCHs are arranged in the frequency coexistence wireless communication system according to the present invention.

FIG. 11 illustrates an example in which a ZPRE is allocated to one of the REs in which PDSCHs of one resource block (RB) are arranged in the frequency coexistence wireless communication system according to the present invention.

12 illustrates an example in which a ZPRE is allocated to one RE in each of a plurality of consecutive resource blocks (RBs) in a frequency coexistence wireless communication system according to the present invention.

FIG. 13 shows an example in which ZPREs are allocated to two REs in each of a plurality of consecutive resource blocks (RBs) in the frequency coexistence wireless communication system according to the present invention.

14 is a view for explaining a configuration example in which all PDSCHs are allocated to ZPRE and an example of DCI designation through a PDCCH in the frequency coexistence wireless communication system according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present invention, if it is determined that the detailed description of the related well-known configuration or function interferes with the understanding of the embodiments of the present invention, the detailed description thereof will be omitted.

In describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

7 is a view for explaining the environment of the frequency-shared wireless communication system 100 according to an embodiment of the present invention.

As shown in FIG. 7, the common frequency use wireless communication system 100 according to an exemplary embodiment of the present invention is a base station (NB) as a licensed band wireless communication system interworking on a network, and user terminal (s) as another licensed band wireless communication system. (UE, User Equipments), and an unlicensed band wireless local area network (WLAN) system according to a protocol such as WiFi.

Here, the NB may be in the form of a mobile communication base station Node B, an eNB, a home-eNB, a relay station, a remote radio head (RRH), an access point (AP), or the like. The NB relays a UE in a macrocell to a mobile communication service through a backhaul in a licensed band according to a mobile communication protocol such as Long Term Evolution (LTE).

In addition, the WLAN system may be in the form of an access point (AP) that forms a small cell such as a pico cell, a femto cell, and the like. The WLAN system relays a UE in a small cell to receive a WLAN communication service such as the Internet through a sidehaul by connecting to a UE in a small cell using an unlicensed band (eg, 5GHz band) such as WiFi according to a protocol such as WLAN.

In such a common frequency use wireless communication system 100 of the present invention, that is, in a wireless communication licensed band (eg, LTE) system operating as a secondary in an unlicensed band (eg, WiFi), mutually with the unlicensed band wireless communication WLAN system In LTE-U service, which coexists and jointly uses an unlicensed band to serve between licensed band (eg, LTE) systems, the licensed band (eg, LTE) systems use a licensed band (eg, WiFi) for a licensed band (eg, LTE). In the case of data transmission / reception, the present invention proposes a method for recognizing an interference situation caused by an unlicensed band (eg, WiFi) signal of an adjacent WLAN system and not using a symbol that causes performance degradation in a reception decoding process.

When the base station (NB) or the user terminal (UE) determines that the channel of the unlicensed band is idle, data can be transmitted.In the case of WiFi, data transmission can be started when a non-WiFi signal of -62dBm or less is detected. have. If LTE and WiFi simultaneously transmit signals in the unlicensed band, reception errors due to mutual interference may occur. Unlike WiFi, LTE can retransmit through HARQ (Hybrid Automatic Repeat and Request), so that the decoding performance can be improved by combining the previously received signal with the retransmitted signal. In this case, in order to effectively decode, it is recommended that a Log Likelihood Ratio (LLR) of a symbol that causes a problem in channel decoding performance be zero or not included.

8 to 13 illustrate examples of downlink reference signals (RSs) and Zero Power (Punctured) Resource Element (ZPRE) in the frequency common wireless communication system 100 of the present invention. Here, an example in which a base station (NB) configures ZPRE with reference signals (RSs) in a downlink resource block (RB) will be described based on a licensed band (eg, LTE) data frame configuration as shown in FIG. 2.

8 to 13, as described above, a cell specific reference signal (CRS) or a common reference signal (CRS) transmitted by a base station (NB) may indicate a transmission mode (eg, LTE transmission mode) 7, 8, and 9. Used for channel estimation for coherent decoding of all downlink physical channels except the physical downlink shared channel (PDSCH).

The DMRS (Demodulation Reference Signal) is used for channel estimation for PDSCH using transmission modes 7,8, 9, 10 as signals specific to each UE.

A control channel (CC) for transmitting control signals such as a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) for transmitting a shared channel are disposed at the remaining REs.

In addition, a multimedia broadcast multicast service single frequency network (MBSFN) RS used before a multicast channel (MCH) and a positioning RS (PRS) used for position estimation may be configured in downlink. In addition, the CSI-RS (Channel State Information-Reference Signal) may be used so that the UE can obtain Channel State Information (CSI) when the DMRS is used for channel estimation. The CSI-RS may not be transmitted in every subframe but may be transmitted at a fairly low time / frequency density.

In the network of the common frequency wireless communication system 100 as shown in FIG. 7, the user terminal UE measures downlink channel estimation or channel state based on the signals and feeds it back to the base station NB. This enables resource management appropriate to the channel situation. In this case, the user terminal (UE) may obtain CQI information by using values such as RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) using the above-described RSs and ZPRE. Can be.

Zero Power (Punctured) Resource Element (ZPRE)

The base station (NB) or the user terminal (UE) may utilize a Signal-to-Interference plus Noise Ratio (SINR) estimated by RS to confirm the existence of the WiFi interference signal. Furthermore, in the present invention, when the base station (NB) downlinks, all or some REs (refer to 810 of FIG. 8) among the resource elements (REs) in which the PDSCH is arranged in one or more resource blocks (RBs) are zero-powered. ZP) (or Puncturing) can be used to transmit the frame. By allowing the downlink signal to be zero power in RE (ZPRE) set to Zero Power (ZP) (or Puncturing), it is easy to detect an unlicensed band (eg WiFi) interference signal in the UE. can do.

Hereinafter, a case in which ZPRE is allocated to an RE where a PDSCH is arranged will be described as an example. However, the ZPRE may also be allocated to an RE where a downlink PDCCH is arranged. In addition, in a RE for which a control channel such as a physical uplink control channel (PUCCH) is arranged for use by the user terminal (UE) during uplink, or a RE for a data channel such as a physical uplink shared channel (PUSCH), ZPRE can be assigned as above.

According to the ZPRE allocation and the frame transmission using the unlicensed band from the base station (NB), the receiver of the user equipment (UE) estimates the interference strength by measuring the level of the unlicensed band (eg, WiFi) interference signal in the ZPRE period. can do. Accordingly, when the UE uses the unlicensed band, the UE may determine whether to decode the channel by checking the number of licensed band (eg, LTE) symbols affected by the interference, and determines whether to perform channel decoding. The uplink data (eg, LTE signal) of the unlicensed band can be processed at the same time as the back signal. Therefore, in the unlicensed band, reception errors due to mutual interference occurring when licensed band (eg, LTE) systems (NB, UE) and unlicensed band (eg, WiFi) WLAN systems simultaneously transmit signals can be prevented. Similarly, when a transmitter of a UE transmits an uplink signal using a ZPRE allocated to a PUCCH or a PUSCH, the base station NB measures a level of an unlicensed band (eg, WiFi) interference signal of a ZPRE interval. The interference intensity can be estimated.

FIG. 8 illustrates an example in which all subcarrier regions 810 of one of REs in which PDSCHs are arranged are allocated to ZPRE in the frequency coexistence wireless communication system 100 of the present invention. For example, all REs in which PDSCHs are arranged in one subcarrier region among 12 subcarriers of a resource block RB may be selected and allocated to ZPRE.

FIG. 9 illustrates an example in which ZPRE is distributedly allocated to a plurality of subcarrier regions 910 among REs in which PDSCHs are arranged in the frequency-shared wireless communication system 100 of the present invention. For example, REs in which PDSCHs are arranged in at least two subcarrier regions among 12 subcarriers of a resource block RB may be selected, and ZPRE may be allocated to at least one RE in each selected subcarrier region.

FIG. 10 illustrates an example in which ZPRE is allocated to two adjacent subcarrier regions while avoiding other reference signals RS among REs in which PDSCHs are arranged in the frequency co-use wireless communication system 100 of the present invention. For example, in the subcarrier region in which the reference signal RS exists among the 12 subcarriers of the resource block RB, all REs in which the PDSCH is disposed may be selected and allocated to the ZPRE. For REs where RS) exists, adjacent REs up or down (frequency direction) may be selected and allocated to ZPRE.

By assigning ZPRE to all resource blocks (RB), ZPRE can be configured for all resources used by all different UEs. In addition, the ZPRE is allocated only to a predetermined specific resource block (RB) so that the channel environment is relatively good, and thus a user terminal (UE) capable of using higher performance modulation (UE) or a small amount of data to be transmitted (buffer) The ZPRE may be configured only in a resource used by a UE (UE) having a small amount of data to be transmitted waiting for the UE.

At this time, the ZPRE allocation to the RE where the PDSCH is arranged may be set by a specific equation or a predefined pattern. For example, the subcarrier position ZPRE_Index (i, k) of the kth ZPRE among the M (natural numbers) ZPREs predetermined in the symbol index (i) is calculated as shown in [Equation 1], and ZPRE is assigned to the corresponding position. Can be. G is a period (eg, the number of resource blocks or subframes) in which ZPRE is allocated. Q (i) may be determined numerically by the symbol index i, and is a zero or positive integer that may be arbitrarily determined in other random permutations. P (k) may be determined mathematically by the ZPRE position k at symbol index i, and is a zero or positive integer that may be arbitrarily determined in a random permutation.

[Equation 1]

ZPRE_Index (i, k) = (Q (i) mod G + P (k) mode G) + (G * k)

Meanwhile, FIG. 11 illustrates an example in which a ZPRE is allocated to one of the REs in which PDSCHs of one resource block (RB) are arranged in the frequency common-use wireless communication system 100 of the present invention.

12 illustrates an example in which ZPRE is allocated to one RE in each of a plurality of consecutive resource blocks (RBs) in the frequency shared wireless communication system 100 of the present invention.

FIG. 13 illustrates an example in which ZPREs are allocated to two REs in each of a plurality of consecutive resource blocks RBs in the frequency shared wireless communication system 100 of the present invention. This is exemplary, and ZPRE may be allocated to three or more REs in each of a plurality of consecutive resource blocks (RBs).

The ZPRE configuration as shown in FIGS. 11, 12, and 13 may be formed by Equation 1, or may be configured by a corresponding RE position predefined in advance. RE may not be configured in all RBs in each OFDM symbol according to G value or system characteristics of Equation (1).

As described above, ZPREs may be allocated to one or more REs among the REs in which PDSCHs are arranged in each of the plurality of resource blocks (RBs), and only one or more subcarriers in each of the plurality of resource blocks (RBs) are shown in FIGS. 8 and 9. In addition, ZPRE may be allocated by combining the ZPRE allocation methods mentioned in 10.

FIG. 14 is a diagram for explaining a configuration example in which all PDSCHs are allocated to ZPRE and an example of DCI designation through a PDCCH in the frequency-shared wireless communication system 100 according to the present invention.

As described above, the ZPRE may be allocated only to a specific resource block (RB) set according to the resource block (RB) configuration allocated to each user terminal (UE), the number, or the transmission rate. The ZPRE may be entirely assigned to the RE where the PDSCH of the block RB is arranged.

The location ZPRE_Index (i, k) of the ZPRE is a DCI (Downlink Control) of a physical downlink control channel (PDCCH) included in a section in which a control channel (CC) for transmitting a control signal is arranged in a resource block (RB). Information), and the user equipment (UE) may measure a short unlicensed band (eg, WiFi) interference signal for a corresponding section designated by the DCI with reference thereto.

[Rate Matching]

In the common frequency wireless communication system 100, when a second license is transmitted / received from an unlicensed band (eg, WiFi) data, the receiver of the user terminal (UE) according to the frame including the ZPRE transmitted from the base station (NB) is a ZPRE interval. The interference intensity may be estimated by measuring the level of the unlicensed band (eg, WiFi) interference signal of the UE, and the transmitter of the UE may be assigned a ZPRE interval (ZPRE) with reference to DCI (or other message or signal). Check the number of REs that can actually transmit data, excluding the location on the subcarrier, and select the corresponding modulation scheme such as Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) through predetermined rate matching. The data to be transmitted can be encoded and transmitted using the selected modulation scheme.

[Pattern Acquisition]

A base station such as an eNB may notify the user equipments (UE) of the pattern of the ZPRE to be used through a system information block (SIB) such as downlink control information (DCI) of a physical downlink control channel (PDCCH). In addition, in order to inform whether a ZPRE is included in a corresponding downlink or uplink subframe, an information bit of a PDCCH may be used.

In addition, the base station (NB) or the user terminal (UE) may notify each other of the presence and location of the ZPRE pattern by using another predetermined message or indication signal to allow the counterpart system to obtain the corresponding information. It may be.

Also, the base station (NB) or the user terminal (UE) blind-decodes a signal received in an uplink or a downlink (for example, if a multiple demodulator is provided and demodulates without information of a modulation scheme) and includes ZPRE. You can also check.

[Incoming decoding]

The receiver of the base station (NB) or the user terminal (UE) may estimate the interference strength by measuring the level of the unlicensed band (eg, WiFi) interference signal of the ZPRE period from the ZPRE of the uplink or downlink frame. Accordingly, when the base station (NB) or the user terminal (UE) uses the unlicensed band, the base station (NB) or the user terminal (UE) may calculate the number of licensed band (eg, LTE) symbols affected by the interference signal (eg, the interference signal is larger than a threshold). .

In addition, based on the strength of the interference signal measured as described above and the number of licensed band (eg, LTE) symbols affected by the interference, whether the base station (NB) or the user terminal (UE) will decode the corresponding channel in the channel decoder. It is possible to determine whether or not to transmit uplink / downlink data (eg, LTE signal) of the unlicensed band at the same time as the WiFi signal of the WLAN system. For example, when the interference signal is larger than the threshold, the reception error due to the interference is large and thus channel decoding may not be performed.

The base station (NB) or the user terminal (UE) responds to a hybrid automatic repeat and request (HARQ) response based on the strength of the interference signal measured as described above and the number of licensed band (eg, LTE) symbols affected by the interference. Receive and determine whether to combine the retransmitted signal and the received signal prior to HARQ, and combine the retransmitted signal and the previously received signal in a predetermined manner to perform channel decoding. By correcting the decoding performance can be improved.

As described above, in the common frequency use wireless communication system 100 according to the present invention, licensed band (eg, LTE) data is obtained using an unlicensed band (eg, WiFi) among user equipments (UE) belonging to an LTE network. In the environment of transmitting and receiving, according to the Zero-powered Resource Element (ZPRE) pattern and the allocation method, it is possible to check the interference section by detecting a short unlicensed band (eg WiFi) interference signal using ZPRE, The number of affected licensed band (eg, LTE) symbols can be identified and processed. Accordingly, it is possible to minimize the effect of high interference signals caused by short unlicensed band (eg WiFi) signals transmitted by unlicensed band (eg WiFi) devices adjacent to the UE, and decoding may be performed to improve reception performance in an interference environment. It is possible to improve decoding performance by combining the previously received signal with the retransmission signal via HARQ.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

A signal processing method for coexisting with an unlicensed band system in a wireless communication system using a licensed band and using the unlicensed band as a secondary,

In the licensed first system, some resource elements RE of at least one resource block RB constituting the data frame of the licensed band are allocated as zero power resource elements ZPRE, and the data frame including the ZPRE is unlicensed band. Transmitting using; And

Receiving the data frame in a licensed band 2 system, measuring the strength of an unlicensed band interference signal in the ZPRE interval, and performing channel decoding

Signal processing method comprising a.
The method of claim 1,

The ZPRE is a total of predetermined REs in which a downlink physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) of an uplink is disposed. Or some REs.
The method of claim 2,

The ZPRE is allocated to the REs of all subcarrier regions of one of the predetermined REs.
The method of claim 2,

And the ZPRE is assigned to one or more REs in each of two or more subcarrier regions of the predetermined REs.
The method of claim 2,

The ZPRE is allocated to all REs in a subcarrier region in which a reference signal exists among the predetermined REs, and is allocated to an RE adjacent to an up or down relative to the RE in which the reference signal exists.
The method of claim 1,

The ZPRE is a predetermined number of M (natural numbers) at the symbol index (i) according to the equation "ZPRE_Index (i, k) = (Q (i) mod G + P (k) mode G) + (G * k)" Assigned to the subcarrier position ZPRE_Index (i, k) of the kth ZPRE of the ZPRE,

Where G is the period in which ZPRE is assigned, Q (i) is a zero or positive integer determined by the symbol index i or randomly determined in a random permutation, and P (k) is the ZPRE at symbol index i. A zero or positive integer determined by position k or randomly determined in a random permutation.
The method of claim 2,

And the ZPRE is allocated to one RE or one of a plurality of REs in each of a plurality of consecutive RBs.
The method of claim 1,

The location on the subcarrier to which the ZPRE is allocated is signaled to the counterpart system using Downlink Control Information (DCI) of the PDCCH or another predetermined message or indication signal.
The method of claim 8,

Confirming the number of REs that can transmit the actual data except for the location on the subcarrier to which the ZPRE is allocated in the licensed band 2 system and transmitting data to be transmitted according to a corresponding modulation scheme

Signal processing method further comprising.
The method of claim 1,

Measuring the strength of the interference signal and performing channel decoding,

Calculating the number of licensed band symbols affected by the interference signal, and determining whether to perform channel decoding based on the strength of the interference signal and the number of symbols;

Signal processing method comprising a.
The method of claim 10,

Measuring the strength of the interference signal and performing channel decoding,

Determining whether to perform channel decoding by combining a signal that is retransmitted with a hybrid automatic repeat and request (HARQ) response and a signal received before the HARQ.

Signal processing method further comprising.