WO2017078185A1

WO2017078185A1 - Method for performing connectionless-based transmission in wireless communication system, and apparatus therefor

Info

Publication number: WO2017078185A1
Application number: PCT/KR2015/011617
Authority: WO
Inventors: 이상림; 고현수; 이호재; 노광석; 김동규
Original assignee: 엘지전자 주식회사
Priority date: 2015-11-02
Filing date: 2015-11-02
Publication date: 2017-05-11

Abstract

A communication method of a mobile station that performs connectionless-based transmission in a wireless communication system may comprise the steps of: determining a PRB and a DMRS cyclic shift value for transmission of a PUSCH; transmitting the PUSCH to a base station on the basis of the determined PRB and DMRS cyclic shift value; randomly redetermining a DMRS cyclic shift value when a negative acknowledgement (NACK) signal for the PUSCH is received from the base station; and retransmitting the PUSCH on the basis of the redetermined DMRS cyclic shift value.

Description

Method for performing connectionless based transmission in wireless communication system and apparatus therefor

The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing connectionless based transmission in a wireless communication system.

In next-generation 5G systems, Massive Machine Type Communications (MTC), which maintains a massive connection and transmits short packets intermittently, is being considered. Massive MTC service has very high Connection Density Requirement, while Data Rate and End-to-End (E2E) Latency Requirement are very free (Connection Density: Up to 200,000 / km2, E2E Latency: Seconds to hours, DL / UL Data) Rate: typically 1-100 kbps).

In addition, in the case of the Cellular Internet of Things (IoT) currently being discussed in the 3GPP GRAN, technology development is being performed in a model in which about 50 000 terminals exist in one cell.

An object of the present invention is to provide a communication method of a terminal for performing connectionless based transmission in a wireless communication system.

Another object of the present invention is to provide a communication method of a base station for performing connectionless based transmission in a wireless communication system.

Another object of the present invention is to provide a terminal for performing connectionless based transmission in a wireless communication system.

Another object of the present invention is to provide a base station for performing connectionless based transmission in a wireless communication system.

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

In order to achieve the above technical problem, a communication method of a terminal performing connectionless based transmission in a wireless communication system includes a physical resource block (PRB) and a DMRS (Physical Uplink Shared CHannel) for PUSCH transmission; Demodulation Reference Signal) determining a cyclic shift value; Transmitting the PUSCH to a base station based on the determined PRB and DMRS cyclic shift value; Randomly determining a DMRS cyclic shift value when receiving a NACK signal for the PUSCH from the base station; And retransmitting the PUSCH based on the re-determined DMRS cyclic shift value. The NACK signal may be transmitted when the PUSCH of the UE and the PUSCH of the other UE are transmitted on the same time and frequency resource based on the same DMRS cyclic shift value, or when the PUSCH of the UE is not received.

The method further includes receiving information about a time and frequency domain for the connectionless based transmission, wherein the determined PRB is included in the time and frequency domain.

The method includes receiving random access preamble index information for the connectionless transmission; And performing a random access procedure based on the random access preamble index information.

In order to achieve the above technical problem, a communication method of a base station for performing connectionless based transmission in a wireless communication system includes a PUSCH (Physical Uplink) based on a determined physical resource block (PRB) and a DMRS cyclic shift value Receiving a shared channel from a terminal; Transmitting a negative ACKnowledgement (NACK) signal for the PUSCH to the terminal; And re-receiving the PUSCH applied to the re-determined DMRS cyclic shift value as a response to the NACK from the terminal, wherein the determined PRB and DMRS cyclic shift value are determined by the terminal, and the re-determined DMRS cyclic shift The transition value may be randomly re-determined by the terminal. The NACK signal may be transmitted when the PUSCH of the UE and the PUSCH of the other UE are transmitted on the same time and frequency resource based on the same DMRS cyclic shift value, or when the PUSCH of the UE is not received.

The method further includes transmitting information on a time and frequency domain for the connectionless transmission, wherein the determined PRB is included in the time and frequency domain.

The method includes transmitting random access preamble index information for the connectionless transmission; And performing a random access procedure based on the random access preamble index information.

In order to achieve the above technical problem, a terminal performing connectionless based transmission in a wireless communication system includes a physical resource block (PRB) and a demodulation reference (DMRS) for physical uplink shared channel (PUSCH) transmission. Signal) a processor configured to determine a cyclic shift value; A transmitter configured to transmit the PUSCH to a base station based on the determined PRB and DMRS cyclic shift value; And a receiver configured to receive a NACK (Negative ACKnowledgement) signal for the PUSCH from the base station, wherein the processor is configured to randomly re-determine a DMRS cyclic shift value when the receiver receives the NACK. May be configured to retransmit the PUSCH based on the re-determined DMRS cyclic shift value.

In order to achieve the above technical problem, a base station performing connectionless based transmission in a wireless communication system includes a physical uplink shared channel (PUSCH) based on a determined physical resource block (PRB) and a DMRS cyclic shift value. A receiver configured to receive a) from the terminal; And a transmitter configured to transmit a negative acknowledgment (NACK) signal for the PUSCH to the terminal, wherein the receiver is configured to re-receive the PUSCH applied to the DMRS cyclic shift value determined as a response to the NACK from the terminal. The determined PRB and DMRS cyclic shift value may be determined by the terminal, and the re-determined DMRS cyclic shift value may be randomly re-determined by the terminal.

A zone allocation and HARQ scheme for uplink connectionless data transmission of a massive terminal is newly proposed to reduce overhead of a base station and efficiently support connectionless transmission of massive terminals.

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

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 is a block diagram showing the configuration of a base station 105 and a terminal 110 in a wireless communication system 100.

2 is an uplink access method of a 3GPP LTE / LTE-A communication system.

3 is a diagram exemplarily illustrating a connection / connectionless zone allocation for supporting both a connection transmission scheme and a connectionless transmission scheme according to the present invention.

4 is a diagram illustrating a procedure of allocating a connection-based zone.

5 is a diagram illustrating a procedure of allocating to a connectionless zone.

6 is a diagram illustrating an example of connectionless transmission as an embodiment of a method of randomly selecting and transmitting a DMRS cyclic shift value when receiving a NACK.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. For example, the following detailed description will be described in detail on the assumption that the mobile communication system is a 3GPP LTE, LTE-A system, but is also applied to any other mobile communication system except for the specific matters of 3GPP LTE, LTE-A. Applicable

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In addition, in the following description, it is assumed that a terminal collectively refers to a mobile or fixed user terminal device such as a user equipment (UE), a mobile station (MS), an advanced mobile station (AMS), and the like. In addition, it is assumed that the base station collectively refers to any node of the network side that communicates with the terminal such as a Node B, an eNode B, a Base Station, and an Access Point (AP). Although described herein based on the IEEE 802.16 system, the contents of the present invention can be applied to various other communication systems.

In a mobile communication system, a terminal or a user equipment may receive information from a base station through downlink, and the terminal may also transmit information through uplink. The information transmitted or received by the terminal includes data and various control information, and various physical channels exist according to the type and purpose of the information transmitted or received by the terminal.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) employs OFDMA in downlink and SC-FDMA in uplink as part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-A (Advanced) is an evolution of 3GPP LTE.

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

Although one base station 105 and one terminal 110 (including a D2D terminal) are shown to simplify the wireless communication system 100, the wireless communication system 100 may include one or more base stations and / or one or more base stations. It may include a terminal.

Referring to FIG. 1, the base station 105 includes a transmit (Tx) data processor 115, a symbol modulator 120, a transmitter 125, a transmit / receive antenna 130, a processor 180, a memory 185, and a receiver ( 190, a symbol demodulator 195, and a receive data processor 197. The terminal 110 transmits (Tx) the data processor 165, the symbol modulator 170, the transmitter 175, the transmit / receive antenna 135, the processor 155, the memory 160, the receiver 140, and the symbol. It may include a demodulator 155 and a receive data processor 150. Although the transmit and receive

antennas

130 and 135 are shown as one in the base station 105 and the terminal 110, respectively, the base station 105 and the terminal 110 are provided with a plurality of transmit and receive antennas. Accordingly, the base station 105 and the terminal 110 according to the present invention support a multiple input multiple output (MIMO) system. In addition, the base station 105 according to the present invention may support both a single user-MIMO (SU-MIMO) and a multi-user-MIMO (MU-MIMO) scheme.

On the downlink, the transmit data processor 115 receives the traffic data, formats the received traffic data, codes it, interleaves and modulates (or symbol maps) the coded traffic data, and modulates the symbols ("data"). Symbols "). The symbol modulator 120 receives and processes these data symbols and pilot symbols to provide a stream of symbols.

The symbol modulator 120 multiplexes the data and pilot symbols and sends it to the transmitter 125. In this case, each transmission symbol may be a data symbol, a pilot symbol, or a signal value of zero. In each symbol period, pilot symbols may be sent continuously. The pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM) symbols.

Transmitter 125 receives the stream of symbols and converts it into one or more analog signals, and further adjusts (eg, amplifies, filters, and frequency upconverts) the analog signals to provide a wireless channel. Generates a downlink signal suitable for transmission via the transmission antenna 130, the transmission antenna 130 transmits the generated downlink signal to the terminal.

In the configuration of the terminal 110, the receiving antenna 135 receives the downlink signal from the base station and provides the received signal to the receiver 140. Receiver 140 adjusts the received signal (eg, filtering, amplifying, and frequency downconverting), and digitizes the adjusted signal to obtain samples. The symbol demodulator 145 demodulates the received pilot symbols and provides them to the processor 155 for channel estimation.

The symbol demodulator 145 also receives a frequency response estimate for the downlink from the processor 155 and performs data demodulation on the received data symbols to obtain a data symbol estimate (which is an estimate of the transmitted data symbols). Obtain and provide data symbol estimates to a receive (Rx) data processor 150. Receive data processor 150 demodulates (ie, symbol de-maps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data.

The processing by symbol demodulator 145 and receiving data processor 150 is complementary to the processing by symbol modulator 120 and transmitting data processor 115 at base station 105, respectively.

The terminal 110 is on the uplink, and the transmit data processor 165 processes the traffic data to provide data symbols. The symbol modulator 170 may receive and multiplex data symbols, perform modulation, and provide a stream of symbols to the transmitter 175. The transmitter 175 receives and processes a stream of symbols to generate an uplink signal. The transmit antenna 135 transmits the generated uplink signal to the base station 105.

In the base station 105, an uplink signal is received from the terminal 110 through the reception antenna 130, and the receiver 190 processes the received uplink signal to obtain samples. The symbol demodulator 195 then processes these samples to provide received pilot symbols and data symbol estimates for the uplink. The received data processor 197 processes the data symbol estimates to recover the traffic data transmitted from the terminal 110.

Processors

155 and 180 of the terminal 110 and the base station 105 respectively instruct (eg, control, coordinate, manage, etc.) operations at the terminal 110 and the base station 105, respectively.

Respective processors

155 and 180 may be connected to memory units 160 and 185 that store program codes and data. The memory 160, 185 is coupled to the processor 180 to store the operating system, applications, and general files.

The

processors

155 and 180 may also be referred to as controllers, microcontrollers, microprocessors, microcomputers, or the like. The

processors

155 and 180 may be implemented by hardware or firmware, software, or a combination thereof. When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the

processors

155 and 180.

Meanwhile, when implementing embodiments of the present invention using firmware or software, the firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention, and to perform the present invention. The firmware or software configured to be may be provided in the

processors

155 and 180 or stored in the memory 160 and 185 to be driven by the

processors

155 and 180.

The layers of the air interface protocol between the terminal and the base station between the wireless communication system (network) are based on the lower three layers of the open system interconnection (OSI) model, which is well known in the communication system. ), And the third layer L3. The physical layer belongs to the first layer and provides an information transmission service through a physical channel. A Radio Resource Control (RRC) layer belongs to the third layer and provides control radio resources between the UE and the network. The terminal and the base station may exchange RRC messages through the wireless communication network and the RRC layer.

In the present specification, the processor 155 of the terminal and the processor 180 of the base station process the signals and data, except for the function of receiving or transmitting the signal and the storage function of the terminal 110 and the base station 105, respectively. For convenience of description, the following description does not specifically refer to the

processors

155 and 180. Although not specifically mentioned by the

processors

155 and 180, it may be said that a series of operations such as a function of receiving or transmitting a signal and a data processing other than a storage function are performed.

In the present invention, a system supporting connection less data transmission for supporting a massive device terminal is considered. We propose a time-frequency resource allocation scheme for connectionless transmission as well as conventional connection-based transmission.

2 is an uplink access method of a 3GPP LTE / LTE-A communication system.

In the existing LTE system, a connection-based transmission method is supported, and in order to support connectivity transmission, the terminal first requests connectivity transmission from a base station through a random access channel (RACH) procedure. 2 shows an RACH performing procedure of a terminal. As shown in FIG. 2, in the LTE / LTE-A system, when a terminal (MS) transmits a random access (RA) preamble to a base station, the base station transmits a RA response to the terminal in response. In this case, the RA response may include Timing Advance, UL grant, and temp C-RNTI. Thereafter, the terminal may perform a radio resource control (RRC) connection setup process with the base station (transmit the RRC connection request message and receive the RRC connection setup message) and then perform data communication with the base station.

However, it is not possible to support massive terminals with connection-based transmission, which is an existing LTE structure. First, in order to support massive terminals in the current structure, it is necessary to secure tremendous frequency resources. However, frequency resources are limited and it is impossible to secure resources indefinitely. In addition, even if the frequency resources are secured, the capacity of the existing base station is also inevitably caused by the increase of the terminal. Therefore, it is obvious that many collisions occur in the process of raising the RACH in the conventional transmission scheme. In order to support a large number of terminals without large changes in the capacity of the existing base station while maintaining the existing frequency resources, a new data transmission scheme is required rather than the conventional connection transmission scheme. In addition, there is a need for a new method for resource allocation when terminals with new functions coexist with existing terminals.

Assume a scenario where an existing terminal (terminal capable of only connection transmission method) and a new terminal (terminal capable of both connection transmission and connectionless transmission method) coexist. As mentioned above, when a large number of terminals increases, the probability of RA collision increases, and even when collision does not occur in the RA, the overload also increases because the base station must manage the RRC context. In addition, when the new terminal is an MTC terminal, the characteristic of the data to be transmitted is often small. In this case, RRC connection request (UL resource) and RRC connection response (DL resource) are used for signaling to send a small amount of data. In other words, the overhead for signaling is greater than the amount of data to be sent, resulting in a highly inefficient system. By using the time-frequency resources occupied by such inefficient signaling as a space for the RACH and using the connectionless transmission, the overhead of the base station for the RRC context can be significantly reduced.

Accordingly, the base station can increase the number of terminals that can be accommodated in the system by allocating a new frequency domain in the case of a terminal that performs connectionless transmission. Here, the connectionless transmission refers to a transmission scheme in which data is initially transmitted to a base station without receiving an R preamble transmission and an RA response (message) and then undergoing an RRC connection process. In this case, there is no need to manage RRC context separately in the network.

The present invention newly defines system information for supporting the connectionless transmission method between the base station and the terminal, and proposes a procedure for controlling the operation of the connectionless connection method and the connection method according to the new access procedure based on the information. The base station may consider operating time-frequency resources as shown in FIG. 3 to support both connected and disconnected schemes.

Referring to FIG. 3, in the connection based transmission zone, the RACH may be allocated to an existing RACH zone and an additional RACH zone may be allocated thereto to reduce the collision probability. In addition, a connectionless transmission zone for connectionless transmission may be allocated to distinguish a connection-based transmission zone from a time resource or a frequency resource. In FIG. 3, connection-based transmission zones and connectionless-based transmission zones are classified by frequency division multiplexing (FDM).

First, in order to know the time-frequency resource allocation type currently used by the base station, the terminal may transmit the following information to the terminal through physical broadcast channel (PBCH), higher layer signaling, and the like.

(1) time-frequency domain for connectionless transmission

(2) RA Preamble index for unconnectable UE

(3) time to maintain connectionless transmission

More specifically, (1) “time-frequency domain for connectionless transmission” is a field indicating an area divided further by time-frequency domain in the connectionless transmission zone as shown in FIG. 3. Information about the region may be previously determined in a table. (2) In the case of “RA Preamble index for non-connectable UE”, it means a new RA Preamble allocation index for UEs that can be additionally connected in addition to the existing RA Preamble. Finally, (3) “Time to maintain connectionless transmission” is a time interval in which a terminal sending data in a connectionless transmission zone can retry in connection transmission mode after a certain time, and must maintain connectionless transmission. It means the minimum time.

After the terminal reads the broadcasted information as described in (1), (2) and (3), the existing terminal performs the procedure in the existing connection transmission scheme. On the other hand, a new terminal capable of both connection and connectionless transmission transmits the RA preamble to the base station using the new RA preamble received by the system information or the RRC signal, and the base station determines whether to allocate to the connectionless transmission area according to the current overhead state. Done. A specific UE and BS access procedure is as shown in FIG. 4.

4 is a diagram illustrating a procedure of allocating a connection-based zone.

4, the terminal transmits any one of the RA preamble allocated for connection-based transmission to the base station. Then, the base station transmits an RA response to the terminal. Unlike the conventional one, an indicator (for example, CL_ind = 0) confirming that the connection-based transmission is allowed (or accepted) may be added and transmitted. Thereafter, the terminal may start connection-based data transmission after performing RRC connection establishment procedures with the base station.

5 is a diagram illustrating a procedure of allocating to a connectionless zone.

In order to inform the base station that connectionless transmission is possible, a terminal supporting both connectionless and connection-based transmission selects one of the RA preambles allocated for connectionless transmission and transmits the RA preamble to the base station. send. After receiving the RA Preamble, the base station may determine whether to allocate to the terminal as an unconnected transmission zone based on the overhead (for example, the number of active terminals) at the current base station.

First assume that there is room in the zone to operate on a connection basis. For example, it may be considered to be 80% or less of the total terminal capacity. In this case, the base station includes an indicator (eg CL_ind = 0) indicating that the base station permits (or accepts) existing connection-based transmission, and the terminal indicates that the UL grant is indicated based on the UL grant included in the RA response. The RRC connection request is transmitted to the base station using the uplink resource and behaves in the same manner as in the conventional operation (see FIG. 3).

On the contrary, FIG. 4 illustrates a procedure of allocating a terminal capable of connectionless transmission to a connectionless zone because the overhead of the base station is severe. In this case, an indicator (for example, CL_ind = 1) is transmitted to the UE to allocate a connectionless transmission zone, and at this time, a zone index indicating which time-frequency domain corresponds to the connectionless transmission zone. It can inform the terminal through. Here, the zone index is an index indicating a corresponding time-frequency domain according to a predefined table in the time-frequency domain for (1) unconnected transmission transmitted by the base station. The terminal may directly transmit data to the base station without performing the RRC connection establishment procedure through the time-frequency domain for the unconnected transmission corresponding to the zone index.

Through the above procedure, the base station can enable the acceptance of a large number of terminals by checking the overhead state of the current base station and allocating a new time-frequency region according to whether the terminal can be connected without connection. As described above, the present invention proposes a scheme for allocating frequency resources in a situation where existing terminals and terminals supporting a new transmission scheme coexist in a system for supporting a massive connection.

Hereinafter, a HARQ design method for uplink connectionless data transmission of a massive terminal after performing the RACH procedure for the massive terminal is proposed. Table 1 below shows uplink HARQ contents in 3GPP LTE system.

Table 1

Uplink HARQ operation scheme in the current LTE system operates synchronously. In more detail, the UE transmits data through a data channel (for example, a physical uplink shared channel (PUSCH)) after 4 subframes, that is, at subframe n + 4, from a time point of receiving a UL grant from a base station (subframe n). The ACK / NACK for the transmitted data is received from the base station through the PHICH in a subframe after 4 subframes (that is, subframe n + 8). If the base station receives the NACK, data is retransmitted after 4 subframes, that is, in a subframe corresponding to subframe n + 12. At this time, the UE should know the information on the resource location and multiplexing in the PHICH ACK / NACK for its uplink data. The PHICH resource information of the ACK / NACK for the uplink data is the lowest physical resource block (PRB) index and the demodulation reference signal (DMRS) in the first slot of the corresponding PUSCH transmission according to the UL grant determined by the base station as shown in Table 1 above. It is determined by cyclic shift.

On the other hand, in case of connectionless transmission, contention is allocated based on a UL grant, and contention-based transmission is performed rather than transmission. In connectionless transmission, the UE determines a resource to be transmitted and a DMRS cyclic shift value. Therefore, when determining the location and multiplexing method of the PHICH based on the lowest PRB index and DMRS cyclic shift in the first slot of the corresponding PUSCH transmission according to the conventional method, another UE using the transmission of the connection method Resources may collide with each other in the PHICH. Therefore, there is a need for a new technique of PHICH resource allocation and multiplexing.

As mentioned above, the code for the location and multiplexing of the PHICH is determined by the lowest index value and the DMRS cyclic shift value of the PRB. In case of transmission using a connectionless method, that is, a contention-based transmission method, the PRB and DMRS cyclic shift values for transmitting the PUSCH are determined by the terminal, not the base station. In this case, a collision may occur if the PHICH is allocated in the current manner. For example, when using a multi-terminal (or user) uplink, the existing LTE scheme allocates the same PRB to different terminals, but multiplexes by setting different DMRS cyclic shift values, and the terminals are multiplexed due to differences in DMRS cyclic shift values. The ACK / NACK of the PHICH can be decoded. However, when UEs determine and use a DMRS cyclic shift value, various UEs may determine an ACK / NACK in a PHICH at the same location. Solutions for solving this problem are described in the following embodiments.

When receiving NACK, a method of randomly selecting and transmitting a DMRS cyclic shift value

We propose a method to prevent a collision when a collision occurs while maintaining an existing PHICH allocation method. For example, if two UEs transmit data (eg, PUSCH) on the same time-frequency resource and the same DMRS cyclic shift value is used, the received base station decodes data of each UE. DMRS and data of each terminal may be divided into an orthogonal code domain, and the used code may be indicated before the data through a preamble.) Then, the ACK / NACK is transmitted to the terminal. When you lower it to the same resource, it uses the same code. Therefore, whether ACK / NACK of the two terminals are not distinguished from each other and it is not known which terminal is ACK / NACK. As a result, two terminals may receive an ACK even if they are not actual ACKs and receive NACKs even if they are not NACKs.

As a method for solving this, the base station gives an ACK to the same position only when the terminals using the same DMRS cyclic shift value for the same time-frequency resources are both ACK, NACK for any one of them Send. In case of NACK terminal, NACK may have occurred due to poor link performance. However, since two UEs use the same DMRS cyclic shift value, the BS may transmit NACK. PUSCH can be transmitted using a new DMRS cyclic shift value different from the one used. If the same DMRS is used for the next transmission, the same phenomenon may continue to occur. Accordingly, resource collision of the PHICH can be reduced by randomly selecting and using a DMRS cyclic shift value.

The base station and the terminal using the preamble

To determine the location of ACK / NACK and the code used

This method is a method of reducing PHICH resource collision by replacing a new key parameter, unlike a method of randomly selecting and transmitting a DMRS cyclic shift value when receiving the NACK described above. In other words, a preamble is used instead of the DMRS cyclic shift value among the lowest PRB index and the DMRS cyclic shift value of the first slot of the existing two parameters corresponding to the PUSCH transmission. Table 2 below shows a Cyclic shift field value of Downlink Control Information (DCI) format 0.

TABLE 2

Referring to Table 2, the DMRS cyclic shift value is currently assigned in the form of 3 bits. Thus, there is a 1/8 chance that DMRS may collide in the same time-frequency resource. In order to reduce the collision probability, a method using a preamble may be used. That is, collision probability can be reduced by allocating a preamble sequence type sufficiently (for example, 32 sequences) or by applying a unique code to the preamble. For example, in connectionless transmission, in order to recognize when data arrives at a base station, a preamble is transmitted before the data in the process of sending data. By assigning a random sequence to this preamble, a key for the corresponding data can be associated.

Referring to FIG. 6, assume a situation in which transmission is performed on the same time-frequency resource. In this case, since each terminal arbitrarily determines and transmits a DMRS cyclic shift value, when transmitting with the same value, even if reception is possible at the base station, two terminals decode ACK / NACK of the same PHICH, which causes a problem. Therefore, by additionally transmitting a random value to the preamble, even if two users transmit the same DMRS cyclic shift value, ACK / NACK allocation of PHICHs orthogonal to each other based on the preamble value is possible. Here, data between terminals can be distinguished at the base station. For example, the classification may be performed through a code domain or a spatial domain.

The base station and the terminal using the preamble before the data

To determine the location of ACK / NACK and the code used

The base station and the terminal described above using a preamble

Unlike the method of determining the location of the ACK / NACK and the code used based on the above, the existing DMRS cyclic shift value is used and the value of the preamble is additionally used. In this method, the collision probability of the PHICH can be reduced by using a random value of the preamble and a conventional DMRS cyclic shift value. The base station and the terminal by using a preamble in front of the data

Compared to the method of determining the location of the ACK / NACK and the code used, the probability of collision can be reduced even if fewer Preamble sequences are used.

In the present invention, a HARQ scheme for a connectionless transmission scheme is proposed. In the case of the existing LTE, while the ACK / NACK location and code of the PHICH is determined based on the values according to the resource allocation of the base station, while determining the location of the ACK / NACK in a new connectionless transmission method (transmission without UL grant) We proposed a method and a method to avoid collisions.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Method for performing connectionless based transmission according to the present invention and apparatus for the same can be used industrially in various wireless communication systems.

Claims

In a communication method of a terminal performing connectionless based transmission in a wireless communication system,

Determining a physical resource block (PRB) and a demodulation reference signal (DMRS) cyclic shift value for PUSCH (Physical Uplink Shared CHannel) transmission;

Transmitting the PUSCH to a base station based on the determined PRB and DMRS cyclic shift value;

Randomly determining a DMRS cyclic shift value when receiving a NACK signal for the PUSCH from the base station; And

And retransmitting the PUSCH on the basis of the re-determined DMRS cyclic shift value.
The method of claim 1,

The NACK signal is transmitted when a PUSCH of the UE and a PUSCH of another UE are transmitted on the same time and frequency resource based on the same DMRS cyclic shift value or when the PUSCH of the UE is not received. Communication method of the terminal to perform.
The method of claim 1,

Receiving information on a time and frequency domain for the connectionless transmission;

The determined PRB is included in the time and frequency domain, the communication method of the terminal for performing connectionless based transmission.
The method of claim 3, wherein

Receiving random access preamble index information for the connectionless transmission; And

And performing a random access procedure based on the random access preamble index information.
A communication method of a base station performing connectionless based transmission in a wireless communication system,

Receiving a physical uplink shared channel (PUSCH) based on the determined physical resource block (PRB) and a DMRS cyclic shift value from the terminal;

Transmitting a negative ACKnowledgement (NACK) signal for the PUSCH to the terminal; And

Re-receiving from the terminal the PUSCH applied to the re-determined DMRS cyclic shift value as a response to the NACK,

The determined PRB and DMRS cyclic shift value is determined by the terminal,

The re-determined DMRS cyclic shift value is randomly re-determined by the terminal, the communication method of the base station for performing connectionless based transmission.
The method of claim 5,

The NACK signal is transmitted when the PUSCH of the UE and the PUSCH of the other UE are transmitted on the same time and frequency resource based on the same DMRS cyclic shift value, or when the PUSCH of the UE is not received. A communication method of a base station performed.
The method of claim 5,

The method may further include transmitting information on a time and frequency domain for the connectionless transmission.

The determined PRB is included in the time and frequency domain, the communication method of the base station for performing connectionless based transmission.
The method of claim 7, wherein

Transmitting random access preamble index information for the connectionless transmission; And

And performing a random access procedure based on the random access preamble index information.
In a terminal for performing connectionless based transmission in a wireless communication system,

A processor configured to determine a Physical Resource Block (PRB) and a Demodulation Reference Signal (DMRS) cyclic shift value for PUSCH (Physical Uplink Shared CHannel) transmission;

A transmitter configured to transmit the PUSCH to a base station based on the determined PRB and DMRS cyclic shift value; And

A receiver configured to receive a negative ACKnowledgement (NACK) signal for the PUSCH from the base station,

The processor is configured to randomly re-determine a DMRS cyclic shift value when the receiver receives the NACK,

The transmitter is configured to retransmit the PUSCH based on the re-determined DMRS cyclic shift value.
A base station performing connectionless based transmission in a wireless communication system,

A receiver configured to receive from the terminal a Physical Uplink Shared CHannel (PUSCH) based on the determined Physical Resource Block (PRB) and a DMRS cyclic shift value; And

Including a transmitter configured to transmit a negative ACKnowledgement (NACK) signal for the PUSCH to the terminal,

The receiver is configured to re-receive the PUSCH applied to the re-determined DMRS cyclic shift value as a response to the NACK from the terminal,

The determined PRB and DMRS cyclic shift value is determined by the terminal,

The re-determined DMRS cyclic shift value is randomly re-determined by the terminal.