KR102249990B1 - Appratus and method for grant-free transmission and demodulation in wireless communication system - Google Patents

Abstract

The present invention confirms the predetermined configuration information for a plurality of available resource blocks and a plurality of demodulation reference signal (hereinafter referred to as DMRS) indices, and K time slot intervals for repetitive transmission of uplink data K times according to the K repetition scheme Each resource block to be used to transmit uplink data is selected, and a mapping variable set to indicate the mapping relationship between the DMRS index and the number of resource blocks is used as the DMRS index to indicate the selected resource block for the previous time slot period. A non-approved transmission device, demodulation device, and non-approved transmission method for disapproving transmission of K uplink data during K time slot intervals by including the DMRS according to the configured DMRS index in the uplink data to be transmitted in the current time slot interval And a demodulation method.

Description

Unauthorized transmission and demodulation device of wireless communication system, unauthorized transmission and demodulation method {APPRATUS AND METHOD FOR GRANT-FREE TRANSMISSION AND DEMODULATION IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to an apparatus for unauthorized transmission and demodulation of a wireless communication system, and a method for unauthorized transmission and demodulation, wherein a plurality of wireless terminals in a cell attempt repetitive transmission and repetition in an environment in which massive Machine Type Communications (mMTC) is attempted. The present invention relates to an apparatus and method for unauthorized transmission of a wireless communication system capable of improving reception performance by applying a continuous interference cancellation technique.

In the 5G communication system, massive machine type communications (mMTC), which supports large-scale access of terminals, was set as one of the main target scenarios. In particular, an environment in which a large number of communication terminals exist, such as an Internet of Things (IoT) environment, and is expected to have various communication requirements for each terminal.

In the mMTC environment, uplink traffic of each terminal is transmitted sporadic in time, and there is a characteristic of a lot of bursty traffic with a small amount of data per transmission. In such an environment, when the uplink transmission scheme of the scheduling scheme used in the existing LTE/LTE-A and 5G NR (new radio) is used as it is, inefficiency due to signaling overhead is high.

1 shows a schematic procedure of a method for controlling an uplink transmission according to a scheduling method.

Referring to FIG. 1, in the scheduling scheme, when data to be transmitted in uplink is generated, a UE transmits a scheduling request to a base station NB. The scheduling request is transmitted to the base station (NB) using a dedicated physical uplink control channel (PUCCH) resource previously allocated for each terminal (S11).

When the scheduling request of the terminal is demodulated, the base station (NB) allocates a resource block, which is a radio resource, to transmit uplink data (S12). In addition, a scheduling grant including information on the allocated resource block is transmitted to the UE after a predetermined time from the time when the UE initially requested scheduling (S13). Here, the scheduling approval may be transmitted to the UE through a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH), and the time interval for transmitting the scheduling approval of the base station (NB) is a subcarrier spacing. It may be adjusted according to, for example, if the subcarrier interval is 15 kHz, it may be set to 8 ms.

When scheduling approval is transmitted, the UE demodulates the scheduling signal through a blind decoding process using a Cell-Radio Network Temporary Identifier (C-RNTI) indicating its identity in the cell, and the resource allocated to it The block is determined (S14). In addition, the UE transmits uplink data using a resource block allocated after a predetermined time from transmission of the initial scheduling request by performing processing as specified by the base station NB (S15).

As shown in FIG. 1, in a scheduling-based uplink transmission process, a base station (NB) controls uplink transmission of all of a plurality of terminals (UEs) in a cell, and all individual terminals (UEs) are scheduled with the base station (NB). The process of exchanging requests and scheduling approvals must be performed. The base station (NB) allocates an available resource block to the terminals that have transmitted the scheduling request, and the terminals allocated the resource block can transmit uplink data without collision with other terminals (UE) by using the resource block. have. However, in the case of an mMTC environment in which a large-scale terminal exists, there is an inefficiency in that signaling overhead becomes too large if all terminals undergo such a control signaling process each time a small amount of data is intermittently transmitted over time.

As a method for solving the inefficiency of the request-approval method, research on a grant-free transmission method that performs uplink transmission without scheduling request and scheduling approval is in progress. The unauthorized uplink transmission scheme can be implemented in two ways. The first method is a contention-based method that randomly selects and transmits one of the available resources when uplink transmission data occurs, and the second method is a contention-free transmission method using dedicated resources. .

The contention-based disapproval transmission technology has a low signaling overhead in that transmission is possible without explicit control signaling, but there is a problem in that transmission reliability may be lowered due to collisions between terminals simultaneously transmitted on the same resource. In order to increase the transmission reliability due to such collision, hybrid automatic repeat request (HARQ) retransmission technology should be applied, but since HARQ retransmission also requires a control signaling procedure between a base station and an individual terminal, there is a problem that signaling overhead is greatly increased.

On the other hand, the contention-free method of disapproval transmission technology can obtain high transmission reliability by utilizing dedicated resources, but there is a problem of inefficient use of resources due to additional signaling for this and fixed resources for a specific terminal.

In the mMTC environment in which a large-scale terminal exists, the amount of physical resources is limited, so a contention-based non-approval transmission technology is used as a basic transmission method, not a contention-based method.

In particular, 3GPP (third generation partnership project), which is responsible for standardization of 5G communication, does not consider retransmission during initial transmission in order to avoid the signaling overhead problem due to retransmission for unauthorized transmission technology in the mMTC environment. We proposed a K repetition technique that repeatedly transmits the same data.

FIG. 2 shows a retransmission scheme in a contention-based disapproved transmission technique, and FIG. 3 shows a K repetition technique in a contention-based disapproved transmission technique.

Referring to FIG. 2, in the retransmission scheme, the UE uses a contention-based disapproval transmission scheme for initial transmission, and if the base station NB fails to demodulate due to collision between the UEs, the UE ) Does not receive an acknowledgment from the base station (NB) (NACK: negative acknowledgment), and subsequent retransmissions are transmitted in a scheduling-based manner.

As shown in FIG. 2, in the retransmission scheme, if the initial transmission fails, retransmission is performed based on scheduling, so retransmission can be performed without collision between terminals. However, in a large-scale access environment such as mMTC, there is a problem in that signaling overhead due to a control signaling procedure between a base station and an individual terminal is large.

Meanwhile, referring to FIG. 3, in the K repetition scheme, the UE performs repetitive transmission of the same data K times (here, as an example, K = 2) upon initial transmission. In addition, when the base station (NB) successfully demodulates one or more data among K transmissions, it transmits an acknowledgment signal (ACK) to the terminal (UE).

In FIGS. 2 and 3, both the UE transmitted data twice, but in the retransmission scheme of FIG. 2, a total of 12 time slots were consumed from the initial transmission to receiving the acknowledgment signal (ACK). , In the K repetition scheme of FIG. 3, it can be seen that a total of 5 time slots are consumed. In addition, in the K repetition scheme, since there is no additional scheduling signal exchanged between the UE and the base station, it is possible to achieve a lower delay time and lower signaling overhead compared to the retransmission scheme.

However, in an environment in which large-scale UEs simultaneously transmit uplink data, there is a problem that the K repetition technique can worsen the collision problem between UEs and degrade demodulation performance of the base station (NB).

Korean Patent Publication No. 10-2017-0123674 (published on November 8, 2017)

An object of the present invention is an unauthorized transmission and demodulation apparatus capable of solving the problem of deterioration of demodulation performance due to data collision in an environment in which a plurality of terminals perform K repetition-based uplink data transmission, such as an ultra-high volume connection (mMTC) environment. However, it is to provide an unauthorized transmission and demodulation method.

Another object of the present invention is a non-approved transmission and demodulation device that enables a base station to estimate a repetitive transmission pattern of a terminal using a demodulation reference signal (DMRS) to check a collision state, and a non-approved transmission. And a demodulation method.

Another object of the present invention is a non-approved transmission that enables a base station to normally demodulate data by removing an interfered signal using a successive interference cancellation (SIC) technique from a collision state determined using DMRS. It is to provide a demodulation apparatus, an unauthorized transmission and a demodulation method.

As a non-approved transmission device according to an embodiment of the present invention to achieve the above object, the terminal checks predetermined configuration information for a plurality of available resource blocks and a plurality of demodulation reference signals (hereinafter, DMRS) indices, and repeats K. Select a resource block to be used to transmit the uplink data in each of the K time slot intervals for repetitive transmission of uplink data K times according to the scheme, and to indicate the mapping relationship between the DMRS index and the number of resource blocks. The set mapping variable is set as the DMRS index to indicate the resource block selected for the previous time slot period, and the DMRS according to the set DMRS index is included in the uplink data to be transmitted in the current time slot period. Unauthorized transmission of uplink data.

The terminal checks a plurality of available DMRS indexes from the configuration information, and the initial DMRS index for selecting a DMRS included in the uplink data transmitted in the first time slot interval is transferred to the mapping variable for the remaining time slot intervals. It is possible to select from DMRS indexes that are not set in the DMRS index set according to the resource block used in the time slot period.

The terminal is an equation among the indexes of a plurality of DMRSs

(Where α _i is the mapping variable, d _i is the DMRS index, N _R is the number of available resource blocks (RBs), N _D is the number of DMRS indexes, and mod is the remainder operator.) _{The index (d i} ) of the DMRS in the current time slot may be set so that (α _i ) represents the resource block used in the previous time slot period among the plurality of resource blocks.

The terminal may set one of the DMRS indexes of the plurality of DMRS indexes such that the value of the mapping variable α _{i becomes 0 as the initial DMRS index.}

The terminal may check a plurality of available resource blocks from the configuration information, and randomly select a resource block to be used in each of K time slot intervals among the confirmed plurality of resource blocks.

As a demodulation apparatus according to another embodiment of the present invention for achieving the above object, a base station broadcasts configuration information including information on an available resource block and a demodulation reference signal (hereinafter, DMRS) index, and from at least one terminal. When uplink data is repeatedly received K times during K time slot intervals using a plurality of resource blocks according to the K repetition scheme, it is determined whether at least one of the uplink data repeatedly received K times is demodulated normally, When at least one uplink data is normally demodulated, the DMRS index, which is the index of the demodulation reference signal (DMRS) determined from the demodulated uplink data, is checked, and the mapping relationship between the DMRS index and the number of resource blocks from the confirmed DMRS index The resource block index for the resource block used in the previous time slot interval is calculated by calculating the value of the mapping variable set based on, and the uplink data transmitted in the previous time slot interval is sequentially obtained using the identified resource block index. Demodulate.

In order to achieve the above object, an unauthorized transmission method of a wireless communication system according to another embodiment of the present invention checks predetermined configuration information for a plurality of available resource blocks and a plurality of demodulation reference signals (hereinafter, DMRS) indices. step; Selecting a resource block to be used for transmitting the uplink data in each of K time slot intervals for repeatedly transmitting uplink data K times according to a K repetition scheme; Setting a mapping variable set to indicate a mapping relationship between a DMRS index and the number of resource blocks as the DMRS index to indicate a resource block selected for a previous time slot period; And disapproving transmission of K uplink data during K time slot intervals by including the DMRS according to the set DMRS index in uplink data to be transmitted in the current time slot interval.

In order to achieve the above object, an unauthorized transmission data demodulation method of a wireless communication system according to another embodiment of the present invention broadcasts configuration information including information on an available resource block and a demodulation reference signal (hereinafter, DMRS) index. The step of doing; When uplink data is repeatedly received K times during K time slot intervals using a plurality of resource blocks according to the K repetition scheme from at least one terminal, at least one of the uplink data repeatedly received K times is normally Determining whether it is demodulated; If at least one uplink data is normally demodulated, checking a DMRS index, which is an index of a demodulation reference signal (DMRS) determined from the demodulated uplink data; And the value of the mapping variable set based on the mapping relationship between the DMRS index and the number of resource blocks from the confirmed DMRS index, and check the resource block index for the resource block used in the previous time slot period, and the identified resource block And sequentially demodulating the uplink data transmitted in the previous time slot period by using the index.

Therefore, in the disapproved transmission and demodulation apparatus and the disapproval transmission and demodulation method according to an embodiment of the present invention, a base station, which is a demodulation apparatus, is repeatedly transmitted K times using a plurality of resource blocks selected in a predetermined manner by each of a plurality of terminals. When at least one of the uplink data among the uplink data is demodulated, a resource block used in a previous time slot may be sequentially estimated by analyzing a DMRS index included in a demodulation reference signal (DMRS) of the demodulated uplink data, It is possible to demodulate previously transmitted uplink data based on information on the estimated resource block. In addition, by using the continuous interference cancellation technique, the demodulated uplink data and data transmitted from another terminal in which collision has occurred can be demodulated together. Therefore, it is possible to prevent deterioration of the demodulation performance of the base station.

1 shows a schematic procedure of a method for controlling an uplink transmission according to a scheduling method.
2 shows a retransmission scheme in a contention-based disapproved transmission technology.
3 shows a K repetition technique in a contention-based disapproval transmission technique.
4 shows a process of intensifying collision between terminals due to the K repetition scheme.
5 shows an example of a resource block configuration in a wireless communication system according to an embodiment of the present invention.
6 is a diagram for explaining a concept of selecting a resource block and setting a demodulation reference signal index according to the selected resource block in a wireless communication system according to an embodiment of the present invention.
7 is a diagram for explaining a process of demodulating uplink data according to a continuous interference cancellation technique when a large-scale collision occurs in the present embodiment.
8 schematically shows an unauthorized transmission method in a wireless communication system according to an embodiment of the present invention.
9 is a diagram showing in detail the operation of the base station in the disapproved transmission method of FIG.
10 is a diagram showing in detail the operation of a terminal in the disapproved transmission method of FIG. 8.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the implementation of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by describing a preferred embodiment of the present invention with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and is not limited to the described embodiments. In addition, in order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals in the drawings indicate the same members.

Throughout the specification, when a certain part "includes" a certain component, it means that other components may be further included, rather than excluding other components unless specifically stated to the contrary. In addition, terms such as "... unit", "... group", "module", and "block" described in the specification mean a unit that processes at least one function or operation, which is hardware, software, or hardware. And software.

4 shows a process of intensifying collision between terminals due to the K repetition scheme.

As described above, in the K repetition scheme, the terminals UE1 and UE2 attempting to access the base station (NB) repeatedly transmit uplink data a designated K number of times regardless of whether or not the base station (NB) successfully demodulates. At this time, the uplink data may be transmitted using a predetermined number of resource blocks (RBs) classified based on frequency, and a resource block (RB) is repeatedly selected for K number of repeated transmissions, and the selected resource block It can be transmitted using (RB).

Although a plurality of terminals (UE1, UE2) each select a resource block (RB) and transmit uplink data using the selected resource block (RB), as shown in FIG. 4, during repeated transmission K times Data collision may occur by selecting the same resource block (RB) in the same time slot and transmitting data (in FIG. 4, for example, n+1 and n+3 time slots).

If the number of selectable resource blocks (RBs) is more than a certain level compared to the number of terminals (UE1, UE2), collisions are difficult to occur frequently, but massive machine type communications (mMTC) environments In an environment in which large-scale terminals simultaneously transmit uplink data, collisions may occur very frequently because the number of resource blocks (RBs) is generally set to be very small compared to the number of terminals (UE1, UE2). Nevertheless, since the number of resource blocks (RBs) that can be used in the wireless communication system is predetermined, the number of resource blocks (RBs) cannot be freely expanded.

That is, in the case of using the K repetitive transmission scheme in the mMTC environment, multiple terminals (UE1, UE2) repeatedly transmit the same data K times, resulting in an increase in the probability of collision, and the base station (NB) transmits uplink It becomes more difficult to demodulate the data. In the worst case, the K repetitive transmission scheme is based on the UE1, because the base station (NB) cannot demodulate the uplink data repeatedly transmitted K times due to collision, despite inefficient operation of the resource for repeatedly transmitting the same data K times. A problem in which UE2) retransmits uplink data may occur frequently.

However, if the base station (NB) can demodulate the uplink data transmitted by each terminal (UE1, UE2) despite collision, the number of retransmissions can be reduced, and thus the efficiency of the K repetitive transmission scheme can be greatly improved. Accordingly, in this embodiment, when the base station (NB) successfully demodulates at least one of the uplink data repeatedly transmitted K times from the terminals (UE1, UE2), a demodulation reference signal included in the uplink data (DeModulation Reference Signal: DMRS) to determine the resource block (RB) used for previous transmission, and to demodulate the uplink data previously transmitted by the terminal (e.g., UE1) based on the determined resource block (RB). I can. In addition, by removing a signal interfered by the uplink data demodulated using a successive interference cancellation (SIC) technique, it is possible to demodulate uplink data in which collision occurs in another terminal UE2. Therefore, it is possible to alleviate the problem that reception performance deterioration occurs in the base station (NB) in the K repetition scheme.

5 shows an example of a resource block configuration in a wireless communication system according to an embodiment of the present invention.

5 shows the configuration of n symbols in a resource block. In a wireless communication system, each of the plurality of resource blocks (RBs) may be composed of m (here, 12 as an example) subcarriers and n (here, 14 as an example) symbols. In the present embodiment, as shown in FIG. 5, p symbols (here, as an example, two) of n symbols of a resource block (RB) may be used as a DMRS.

The DMRS is generally used for estimating a resource block (or channel) used by the UE to transmit uplink data, and may transmit a Zadoff-Chu (ZC) sequence code as an example. Since the ZC sequence has a constant amplitude zero auto-correlation (constant Amplitude Zeor Auto-Correlation: hereinafter CAZAC), if a plurality of terminals select different ZC sequence indexes, the base station (NB) is the ZC transmitted from each of the plurality of terminals. The sequence index can be classified and detected. If a wireless communication system applies a cyclic shift and an orthogonal cover code (OCC) when generating a ZC sequence, the available ZC sequence index, that is, the number of ZC sequences, is greatly increased. do.

In addition, in this embodiment, when at least one of the uplink data repeatedly transmitted K times from the terminal (UE) is demodulated, the DMRS is a resource so that the index of the resource block (RB) used in the previous time slot interval can be checked. It is used to provide block (RB) information. In particular, it may indicate the index of the resource block (RB) used in the previous time slot.

In the K repetition scheme, each of a plurality of terminals (UE1, UE2) selects a number of resource blocks (RBs) to be used during the _{K time slots (t 0} ~ t _{K-1 ), and uses the selected resource blocks (RBs).} Transmit uplink data. In this case, the DMRS of each resource block (RB) includes a ZC sequence index, that is, DMRS index information, selected in correspondence with the index for the resource block (RB) used in the previous time slot.

Accordingly, the base station (NB) is based on the DMRS index information included in the DMRS of the demodulated uplink data among the K uplink data transmitted during the _{K time slots (t 0} to t _{K-1 ).} The used resource block (RB) can be determined.

Therefore, in this embodiment, the DMRS is a reference signal provided to allow the base station (NB) to classify data according to the ZC sequence index as well as to estimate the resource block (RB) used by the terminals (UE1, UE2). (NB) is a resource used by each terminal (UE) with a high probability even if a plurality of terminals (UE1, UE2) select the same ZC sequence index when the resource block (RB) used by the terminals (UE1, UE2) is estimated from the DMRS. Data can be detected by successfully separating the blocks RBs. Accordingly, the base station can demodulate uplink data by classifying it according to not only the ZC sequence index but also the used resource block (RB).

Accordingly, in this embodiment, if the base station (NB) can demodulate at least one of the uplink data repeatedly transmitted K times from the specific terminal (UE1), all of the uplink data transmitted before the demodulated uplink data is It can demodulate, and by applying the demodulated uplink data to the SIC scheme, uplink data that has been transmitted from another terminal (UE2) and generated collision can also be demodulated by removing interference.

A technique for demodulating by removing interference of collided data using the SIC technique is a known technique, and thus a detailed description thereof is omitted here.

In this embodiment, a plurality of terminals UE1 and UE2 may be referred to as non-approved transmission devices, and the base station NB may be referred to as a demodulation device.

6 is a diagram for explaining a concept of selecting a resource block and setting a demodulation reference signal index according to the selected resource block in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 6, the UE selects a resource block (RB) to be used during K time slot periods. Here, the UE may randomly select a resource block (RB) to be used in each time slot period, for example.

And the terminal (UE) is based on the mapping variable (α _i ) set according to the mapping relationship between the number of resource blocks (RB) (N _R ) and the DMRS index, the DMRS index is the resource block (RB) used in the previous time slot. Select a DMRS index in each time slot to indicate the index of ).

When the number of indexes of the entire DMRS is N _D and the number of all resource blocks (RBs) is N _R , the index set (Φ) of the DMRS is Φ = (d ₁ , d ₂ ,… , d _ND }, and d _i represents the i (1 ≤ i ≤ N _D )-th DMRS index.

The DMRS index d _i may be selected to indicate the index of the resource block RB used in the previous time slot according _{to the mapping variable α i} according to Equation 1, for example.

According to Equation 1, the mapping variable α _i is set according to the mapping relationship between the DMRS index and the number of resource blocks RB (N _{R) based on a modulo operation, and the corresponding resource block RB} You can express the index of ).

Accordingly, when the UE repeatedly transmits uplink data by repeating K times according to the K repetition technique, the mapping variable α _i obtained according to Equation 1 is the index of the resource block RB used in the previous time slot. _{The index (d i} ) of the DMRS to be included in the uplink data transmitted in each time slot may be selected to represent.

In FIG. 6, as an example, it is assumed that the _{number of DMRS indexes (N D} ) is 32 and the number of resource blocks (RBs), that is, the number of indexes (N _{R) of resource blocks is 4.}

_{In the second time slot period t 1} in the 4 time slot periods shown in FIG. 6, the UE has an index of the resource block RB used in the previous time slot period t _{0, so 32} Among the DMRS indexes, _{the index (d i} ) of the DMRS such that the _{mapping variable (α i} ) is 3 is selected. Here, since it is assumed that the number of resource blocks (RBs) is 4, the UE may select a DMRS index remaining by dividing by 5 among the DMRS indices from 1 to 32. That is, one of the DMRS indexes (d ₃ , d ₈ , d ₁₃ , d ₁₈ , d ₂₃ , d ₂₈ ) (here, as an example, d ₁₈ ) may be selected. Then, the DMRS according to the selected DMRS index is included in the uplink data and transmitted to the base station (NB).

In addition, since the index of the resource block (RB) used in the previous time slot period (t ₁ ) in the third time slot period (t _{2 ) is 2, the mapping variable (α i} ) among 32 DMRS indices is Select one of the DMRS indexes to be 2 (d ₂ , d ₇ , d ₁₂ , d ₁₇ , d ₂₂ , d ₂₇ , d ₃₂ ) (here, d ₂₇ as an example), and the selected DMRS index (d _i ) DMRS according to may be included in uplink data and transmitted.

Here, as described above, the DMRS may be a ZC sequence, and the DMRS index may be an index of a ZC sequence.

Meanwhile, in the case of the first time slot (t ₀ ) among uplink data repeatedly transmitted K times, there is no resource block (RB) used in the previous time slot. Accordingly, the UE _{transmits the uplink data transmitted in the initial time slot t 0} including the DMRS according to the separately selected initial DMRS index (d _{i, t 0 ).} Here, the index of the initial DMRS (d _{i, t0 ) is by selecting one of the indexes (d i} ) of the DMRS that cannot be selected in the remaining time slot period, so that the base station (NB) is the index of the initial DMRS (d _{i, t0} ). Can be made to discriminate.

In addition, in the remaining time slots (t ₁ to t ₃ ) excluding the first time slot (t ₀ ), the mapping variable (α _i ) must indicate the index of the resource block (RB) used in the previous time slot, so it cannot be 0. . Accordingly, in this embodiment, the index of the initial DMRS (d _{i, t0} ) is the index of the DMRS (d ₀ , d ₅ , d ₁₀ , d ₁₅ , d ₂₀ , d ₂₅ , d) so that the mapping variable α _{i becomes 0. It} is assumed that ₃₀ ) is selected as one of (here, as an example, d 30 ).

As a result, in this embodiment, the UE is _{based on the mapping variable α i} indicating the mapping relationship between the _{DMRS index and the number of resource blocks RBs (N R} ), and the resource block used in the previous time slot ( _{A DMRS index (d i} ) corresponding to the index of RB) may be selected, and _{a DMRS according to the selected DMRS index (d i} ) may be included in uplink data and transmitted.

The relationship between equation (1) in the mapped variable (α _i) has been described as being obtained using a modulo operation, the mapping parameters (α _i) the DMRS index (d _i) and the number of resource blocks (RB) (N _R) It may be obtained according to another operation that allows the index of the resource block RB to be estimated from.

7 is a diagram for explaining a process of demodulating uplink data according to a continuous interference cancellation technique when a large-scale collision occurs in the present embodiment.

The base station (NB) analyzes the DMRS of the demodulated uplink data when demodulation is normally performed because a collision does not occur in at least one of the uplink data that is repeatedly transmitted K times.

In FIG. 7, a specific terminal UE1 includes a sixth resource block (RB6), a fourth resource block (RB4), a second resource block (RB2), a fifth resource block (RB5), a third resource block (RB3), and a third resource block (RB3). Uplink data is repeatedly transmitted 6 times in the order of 1 resource block (RB1), and uplink data other than the uplink data transmitted to the first resource block (RB1) is simultaneously uplink data from a plurality of UEs. A case in which a large-scale collision occurs by transmitting is illustrated.

In this case, the base station NB may normally demodulate uplink data in which no collision has occurred by using the first resource block RB1 in the _{time slot t 5. In addition, the DMRS index (d i} ) is checked by analyzing the DMRS included in the normal demodulated uplink data. And determine the DMRS index (d _i) from the mapping parameters (α _i) to calculate the previous time slot (t ₄₎ to the base index of the resource blocks to determine the index, and determines a resource block (RB) used in the previous By repeating the process of analyzing the DMRS by demodulating the uplink data transmitted in the time slot t ₄ , it is possible to demodulate all of the previous uplink data up to the _{initial time slot t 0.} At this time, the base station (NB) determines whether the analyzed DMRS index (d _i ) is the initial DMRS index (d _{i, t0} ), and if it is determined as the initial DMRS index (d _{i, t0} ), the previously transmitted uplink data does not exist. It is determined not to perform an additional demodulation process.

In addition, the base station (NB) may demodulate uplink data in which collision occurs according to the SIC scheme by simultaneously transmitting the other UE2 among the demodulated uplink data using the same resource block (RB).

As a result, when at least one of the uplink data repeatedly transmitted K times from one terminal (UE1) is normally demodulated by the base station (NB), all previously transmitted uplink data can be demodulated, and the demodulated uplink data is transmitted. Uplink data transmitted from another terminal (UE2) that caused a collision in the process of becoming a collision may also be demodulated according to the SIC scheme. Therefore, even if a collision occurs in all of the uplink data transmitted by the other terminal (UE2) repeatedly K times, the base station (NB) allows the base station (NB) to demodulate at least one of the uplink data transmitted by the other terminal (UE2), so that the other terminal (UE2) does not need to retransmit uplink data. In addition, this enables the UE2 to demodulate again the uplink data transmitted from another terminal causing a collision with the uplink data repeatedly transmitted K times.

Here, the number of cases for a pattern in which each of a plurality of terminals (UE1, UE2) selects a resource block (RB) is (N _R ) ^K, and the pattern in which two different terminals select a resource block (RB) coincide. The probability of doing is (1/N _R ) ^K. And in this embodiment, the base station (NB) can demodulate all of the uplink data previously transmitted from the corresponding terminal (UE1) even if only one of the uplink data that is repeatedly transmitted K times is normally demodulated, and collides with the demodulated uplink data. The uplink data transmitted from the other terminal UE2 generated can also be demodulated using the SIC scheme.

That is, even when a very large number of terminals transmit uplink data to the base station (NB), such as in an mMTC environment, the base station (NB) demodulates the uplink data transmitted from multiple terminals (UE1, UE2) with a very high probability. can do. Accordingly, it is possible to prevent deterioration of the demodulation performance of the base station (NB).

8 schematically shows an unauthorized transmission method in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 8, the base station (NB) first broadcasts disapproval configuration information for K repetition-based disapproval transmission (S11). The base station (NB) can broadcast including information such as DMRS configuration information, resource block (RB) configuration information, and repetition parameter (K), for example, and system information used for broadcasting in an existing wireless communication system. Block (System Information Block: SIB) may be used to broadcast disapproved configuration information.

Here, the DMRS configuration information includes information on available DMRS and a DMRS index (d _i ), and the DMRS is, for example, a ZC sequence, and the DMRS index (d _i ) may be an index of a ZC sequence. In addition, the resource block (RB) setting information includes information on a usable resource block (RB) and a resource block (RB).

Each of a plurality of UEs uses a system information radio network temporary identifier (SI-RNTI), which is a system parameter, to blind decoding the broadcasted data to disapprove configuration information. Can be obtained.

Each of a plurality of UEs having obtained disapproval configuration information determines whether there is uplink data to be transmitted to the base station (NB), and if uplink data is present, during K time slot periods according to the K repetition scheme. Resource blocks (RBs) to transmit uplink data to be repeatedly transmitted are selected. Here, the resource blocks RBs may be selected at random, and in some cases, may be selected in a predetermined pattern.

And the number of DMRS indexes (d _i ) and resource blocks (RBs) from the number of DMRSs (equal to the number of DMRS indexes (N _D )) and the number of resource blocks (RBs) (N _{R) identified in the disapproval setting information} The _{DMRS index d i} is selected and set so that the mapping variable α _{i representing the mapping relationship between N R} ) can each represent the index of the resource block RB selected for the previous time slot period.

However, the UE sets the initial DMRS index (d _{i, t0 ) for the first time slot interval among the K time slot intervals by selecting a DMRS index (d i} ) that cannot be selected for the remaining time slot intervals. It allows the base station (NB) to recognize that _{the initial DMRS index (d i,t0) for the initial time slot period.}

The terminal (UE) sequentially transmits the DMRS according to the K DMRS indexes (d _i,t0 , …, d _{i,t(K-1) ) selected based on the mapping variable (α i ).} And sequentially transmits K uplink data using a selected resource block (RB) (S13).

The base station (NB) demodulates uplink data repeatedly transmitted K times through at least one resource block (RB) selected by the terminal (UE), and demodulates at least one of the uplink data repeatedly transmitted K times. Then, the resource block (RB) used for transmission of the previously transmitted uplink data is checked from the DMRS index checked in the DMRS of the demodulated uplink data, and previously transmitted according to the information of the confirmed resource block (RB). Uplink data is demodulated, and uplink data is sequentially demodulated. Thereafter, based on the demodulated uplink data, uplink data transmitted from another terminal but in which collision has occurred is demodulated according to the SIC scheme (S14).

When the base station (NB) successfully demodulates the uplink data transmitted from the terminal (UE), it transmits an acknowledgment signal (ACK) to the terminal (UE). However, if demodulation is not normally performed, a response cannot be transmitted (NACK) (S15).

9 is a diagram showing in detail the operation of a base station in the disapproved transmission method of FIG. 8.

Referring to FIG. 9, the base station (NB) broadcasts disapproval configuration information for K repetition-based disapproval transmission (S111). As described above, the disapproval configuration information may include DMRS configuration information, resource block (RB) configuration information, repetition parameter (K), and the like, and may be broadcast using SIB.

Then, it is determined whether uplink data is received from at least one terminal (UE) (S112). If uplink data is received, the received uplink data is demodulated (S113). When no collision occurs in the uplink data, the uplink data can be demodulated normally, and the base station (NB) determines whether the received uplink data is normally demodulated (S114).

_{Then, the DMRS index (d i} ) is checked by analyzing the DMRS of the normal demodulated uplink data, and between the DMRS index (d _i ) and the number of resource blocks (RBs) (N _R ) from the confirmed DMRS index (d _{i ). A mapping variable α i} indicating the mapping relationship of is acquired (S115). When the mapping variable α _i is acquired, the base station NB determines whether the DMRS index (d _i ) of the demodulated uplink data is the initial DMRS index (d _{i, t0 ) according to the acquired mapping variable α i} (S116). If it is not the initial DMRS index (d _{i, t0} ), the index of the resource block (RB) used in the previous time slot is checked from the mapping variable (α _{i) (S117).} Then, the uplink data transmitted in the previous time slot is sequentially demodulated according to the identified resource block (RB) (S118).

And, when at least one of the uplink data repeatedly transmitted K times is demodulated normally, the base station (NB) transmits a response signal (ACK) to the terminal (UE) that has transmitted the uplink data (S119).

Meanwhile, the base station (NB) determines whether there is collided data by using the same resource block (RB) as the uplink data demodulated by another terminal (S120). When the collided data exists, the collided data may be demodulated by applying the SIC technique to remove interference caused by the demodulated uplink data (S121).

10 is a diagram showing in detail the operation of a terminal in the disapproved transmission method of FIG. 8.

Referring to FIG. 10, the UE first receives and demodulates data broadcast by the base station NB to obtain disapproval configuration information (S211). Each of a plurality of UEs may obtain disapproval configuration information by blind-decoding corresponding broadcast data using SI-RNTI or the like.

In addition, the UE determines whether there is uplink data to be transmitted to the base station (S212). If there is uplink data to be transmitted, at least one resource block (RB) to be used during K time slots is selected based on DMRS configuration information and resource block (RB) configuration information included in the disapproval configuration information (S213) ).

Meanwhile, the UE may select one of a plurality of DMRS indexes (d _i ) determined from the DMRS configuration information as an initial DMRS index (d _{i, t0} ) according to a known method, and the remaining DMRS indexes (d _{i, t1} , d _i,t2 , …, d _i,t(K-1) ) can be selected based on the _{mapping variable α i} to indicate the index of the resource block RB selected for the previous time slot period ( S214). Here, the mapping variable α _i is a variable set in advance to be calculated by a function capable of representing a mapping relationship between the DMRS index d _i and the number of resource blocks RB (N _{R ).}

Here, in the case of the initial DMRS index (d _{i, t0} ) selected for the first time slot interval among K time slot intervals, it may be selected to derive _{a mapping variable α i} value that cannot be obtained in the subsequent time slot interval. .

And the DMRS according to the remaining DMRS indexes (d _i,t1 , d _i,t2 , …, d _i,t(K-1) ) set from the initial DMRS index (d _i,t0 ) is repeated for each K time slot period. Included in the uplink data to be transmitted, and sequentially transmits K uplink data including DMRS to the base station (NB) using the selected resource block (RB) (S215).

Thereafter, the UE determines whether an acknowledgment signal ACK is received from the base station NB (S216). If the acknowledgment signal (ACK) is received, it is determined that the uplink data transmitted by the base station (NB) has been normally received and demodulated, and the uplink in which disapproval configuration information broadcasted from the base station (NB) must be acquired or transmitted. It is determined whether data exists (S211, S212). However, if the acknowledgment signal (ACK) is not received from the base station (NB) for a predetermined period of time, a resource block index may be selected again, and a DMRS index (d _i ) may be set from the selected resource block index (S213).

The method according to the present invention can be implemented as a computer program stored in a medium for execution on a computer. Here, the computer-readable medium may be any available medium that can be accessed by a computer, and may also include all computer storage media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, and ROM (Read Dedicated memory), RAM (random access memory), CD (compact disk)-ROM, DVD (digital video disk)-ROM, magnetic tape, floppy disk, optical data storage device, and the like.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those of ordinary skill in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (18)

Check predetermined configuration information for a number of available resource blocks and a number of demodulation reference signal (hereinafter referred to as DMRS) indices,
Selecting a resource block to be used to transmit the uplink data in each of K time slot intervals for repeatedly transmitting uplink data K times according to the K repetition scheme,
A mapping variable set to indicate the mapping relationship between the DMRS index and the number of resource blocks is set as the DMRS index to indicate the resource block selected for the previous time slot period,
A terminal that includes a DMRS according to the set DMRS index in the uplink data to be transmitted in the current time slot interval and transmits K uplink data without approval during the K time slot intervals. The method of claim 1, wherein the terminal
The initial DMRS index for checking a plurality of available DMRS indexes from the configuration information and for selecting a DMRS included in the uplink data transmitted in the first time slot interval is the mapping variable and the previous time slot interval for the remaining time slot intervals. A terminal that selects and configures a DMRS index that is not set from a DMRS index set according to a resource block used in. The method of claim 1, wherein the terminal
Among the indexes of multiple DMRSs
Equation

(Where α _i is the mapping variable, d _i is the DMRS index, N _R is the number of available resource blocks (RBs), N _D is the number of DMRS indexes, and mod is the remainder operator.)
The terminal configured to set _{the index (d i} ) of the DMRS in the current time slot so that the mapping variable α _i defined according to may indicate a resource block used in a previous time slot interval among a plurality of resource blocks. The method of claim 3, wherein the terminal
A terminal configured to set one of the DMRS indexes that causes the value _{of the mapping variable α i} among the indexes of a plurality of DMRSs to be 0 as the initial DMRS index. delete Broadcasting configuration information including information on available resource blocks and demodulation reference signal (hereinafter referred to as DMRS) index,
When uplink data is repeatedly received K times during K time slot intervals using a plurality of resource blocks according to the K repetition scheme from at least one terminal, at least one of the uplink data repeatedly received K times is normally Determine whether it is demodulated,
When at least one uplink data is normally demodulated, a DMRS index, which is an index of a demodulation reference signal (DMRS) determined from the demodulated uplink data, is checked, and
Based on the mapping relationship between the DMRS index and the number of resource blocks from the identified DMRS index, the value of the set mapping variable is calculated, and the resource block index for the resource block used in the previous time slot is checked, and the identified resource block index The base station sequentially demodulates the uplink data transmitted in the previous time slot period by using. The method of claim 6, wherein the base station
If the DMRS index included in the DMRS of sequentially demodulated uplink data does not correspond to the available resource block index, the base station is determined by the initial DMRS index transmitted in the first time slot interval among K time slot intervals. The method of claim 6, wherein the base station
Among the uplink data transmitted from other terminals, it is determined whether demodulated uplink data and uplink data with collisions exist, and if there is uplink data with collisions, it is demodulated using a continuous interference cancellation (SIC) technique. The base station demodulates uplink data in which collision occurs by removing interference caused by the uplink data. The method of claim 6, wherein the base station
Checked DMRS index (d _i )
Equation

(Where α _i is the mapping variable, N _R is the number of available resource blocks (RBs), N _D is the number of indexes of the DMRS, and mod is the remainder operator.)
A base station that calculates _{the mapping variable α i} representing a resource block used in a previous time slot interval among a plurality of resource blocks by substituting in. Confirming predetermined configuration information for a plurality of available resource blocks and a plurality of demodulation reference signal (hereinafter referred to as DMRS) indices;
Selecting a resource block to be used for transmitting the uplink data in each of K time slot intervals for repeatedly transmitting uplink data K times according to a K repetition scheme;
Setting a mapping variable set to indicate a mapping relationship between a DMRS index and the number of resource blocks as the DMRS index to indicate a resource block selected for a previous time slot period; And
Including the DMRS according to the set DMRS index in the uplink data to be transmitted in the current time slot interval, and transmitting the K number of uplink data disapproved during the K time slot intervals. The method of claim 10, wherein the setting of the DMRS index comprises:
The initial DMRS index for checking a plurality of available DMRS indexes from the configuration information and for selecting a DMRS included in the uplink data transmitted in the first time slot interval is the mapping variable and the previous time slot interval for the remaining time slot intervals. Unauthorized transmission method of a wireless communication system that selects and sets from DMRS indexes that are not set from a DMRS index set according to a resource block used in. The method of claim 10, wherein the setting of the DMRS index comprises:
Among the indexes of multiple DMRSs
Equation

(Where α _i is the mapping variable, d _i is the DMRS index, N _R is the number of available resource blocks (RBs), N _D is the number of DMRS indexes, and mod is the remainder operator.)
The ratio of the wireless communication system for setting _{the index of the DMRS (d i} ) in the current time slot so that the mapping variable α _i defined according to is to indicate the resource block used in the previous time slot period among the plurality of resource blocks. How to send approval. The method of claim 12, wherein the setting of the DMRS index comprises:
A method of disapproving transmission of a wireless communication system in which one of the DMRS indexes, which causes the value _{of the mapping variable α i} among a plurality of DMRS indices to be 0, is set as the initial DMRS index. delete Broadcasting configuration information including information on an available resource block and a demodulation reference signal (hereinafter referred to as DMRS) index;
When uplink data is repeatedly received K times during K time slot intervals using a plurality of resource blocks according to the K repetition scheme from at least one terminal, at least one of the uplink data repeatedly received K times is normally Determining whether it is demodulated;
If at least one uplink data is normally demodulated, checking a DMRS index, which is an index of a demodulation reference signal (DMRS) determined from the demodulated uplink data; And
Based on the mapping relationship between the DMRS index and the number of resource blocks from the identified DMRS index, the value of the set mapping variable is calculated, and the resource block index for the resource block used in the previous time slot is checked, and the identified resource block index A method of demodulating unauthorized transmission data of a wireless communication system, comprising the step of sequentially demodulating uplink data transmitted in a previous time slot period by using. The method of claim 15, wherein the demodulating step
If the DMRS index included in the DMRS of sequentially demodulated uplink data does not correspond to the available resource block index, it is determined as the initial DMRS index transmitted in the first time slot interval among K time slot intervals, and A method of demodulating unauthorized transmission data in a wireless communication system that does not perform additional demodulation for the wireless communication system. The method of claim 15, wherein the unauthorized transmission data demodulation method
Determining whether the demodulated uplink data and uplink data in which collisions occur among uplink data transmitted from another terminal exist;
Demodulating uplink data in which collision occurs by removing interference by uplink data demodulated using a continuous interference cancellation (SIC) technique if there is uplink data in which collision occurs; Unauthorized transmission data demodulation method of a wireless communication system further comprising a. The method of claim 15, wherein the demodulating step
Checked DMRS index (d _i )
Equation

(Where α _i is the mapping variable, N _R is the number of available resource blocks (RBs), N _D is the number of indexes of the DMRS, and mod is the remainder operator.)
A method for demodulating unauthorized transmission data of a wireless communication system for calculating _{the mapping variable α i} representing a resource block used in a previous time slot interval among a plurality of resource blocks by substituting for.

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