WO2013168872A1 - Method for enhanced uplink transmission having low papr in lte-based mobile communication system - Google Patents

Description

Improved Downlink Transmission Method with Low PA in LTE-based Mobile Communication Systems

The present invention is based on the existing LTE-based downlink in the LTE-based mobile communication system downlink that can degrade performance due to the peak to average power ratio (PAPR) problem of multi-carrier transmission due to the non-linearity of the power amplifier in the base station including the satellite The present invention relates to a communication method for downlink transmission having low PAPR while having compatibility with transmission.

The present invention was carried out as a result of the research and development of the broadcasting and telecommunications infrastructure source technology of the Korea Communications Commission. [KCA-2012-12-911-01-201, Development of Optimum Application Technology of 2.1GHz Satellite Frequency Band for Terrestrial Mobile Communication]

The present invention is based on the existing LTE-based downlink in the LTE-based mobile communication system downlink that can degrade performance due to the peak to average power ratio (PAPR) problem of multi-carrier transmission due to the non-linearity of the power amplifier in the base station including the satellite The present invention relates to a communication method for downlink transmission having low PAPR while having compatibility with transmission.

The LTE downlink transmission scheme is based on orthogonal frequency division multiplex (OFDM). OFDM is an attractive downlink transmission scheme for various reasons. Due to the relatively long OFDM symbol intervals with Cyclic Prefix (CP), OFDM is very robust to the frequency selectivity of the channel. In principle, the equalizer of the receiver can be used to solve the signal damage caused by the frequency selective channel. However, the complexity of the equalizer begins to be too high for a terminal using a bandwidth larger than 5 MHz. Therefore, OFDM has been in the spotlight as a downlink transmission method especially when using a bandwidth larger than 5 MHz due to the inherent robustness to the frequency selectivity of the channel. On the other hand, LTE uplink uses a DFTS-OFDM (Discrete Fourier Transform Spread-OFDM) based single carrier transmission scheme. The reason for using the single carrier modulation method in the uplink is that the PAPR of the transmission signal in the single broadcast transmission method is lower than that of the multicarrier transmission method such as OFDM. The smaller the PAPR of the transmitted signal, the higher the average transmit power can be for a given power amplifier. Thus, single carrier transmission yields higher power amplifier efficiency, which means increased coverage and reduced terminal power consumption.

In LTE-based terrestrial mobile communication systems, OFDM transmission is sensitive to PAPR, but it is considered to be less sensitive to PAPR by using a power amplifier with relatively good performance because it maintains flexibility in resource allocation in the frequency domain. DFTS-OFDM transmission has been considered in uplink which may be sensitive to PAPR because there are many limitations in resource allocation in order to maintain a single carrier characteristic, but due to the terminal price, a good amplifier cannot be used. However, in the case of satellite mobile communication system, due to the non-selective feature of the satellite channel, the resource allocation in the frequency domain is less important than the terrestrial system, and the satellite power amplifier is very sensitive to PAPR. Nonlinearity of the power amplifier during transmission causes performance degradation. That is, in a PAPR-sensitive mobile communication system due to nonlinearity of a power amplifier in a base station such as a satellite mobile communication system, a single carrier transmission may improve performance than a multicarrier.

However, the future mobile communication network is expected to evolve in the direction of combining or cooperating with the terrestrial network and the satellite network, so the commonality between the satellite and the terrestrial air interface in such a satellite / terrestrial integrated system is very important considering the cost of the terminal. Should be. In particular, considering that LTE-based land mobile systems are considered as the next generation IMT-Advanced system, the wireless interface of the satellite mobile communication system reuses existing land terminals when maintaining commonality with that of the LTE-based land mobile communication network. This has the advantage of realizing economies of scale. On the other hand, without considering commonality with the terrestrial network, the satellite mobile system can reduce the overhead of the satellite payload by using the wireless interface optimized for the satellite environment and implement the system optimized for the satellite mobile environment. have. However, in order for a terminal to use both satellite and terrestrial services, the terminal must have a dual-mode chip for supporting satellite and terrestrial wireless interfaces. In other words, the LTE-based satellite mobile communication system considering the LTE-based ground mobile system has the commonality with the terrestrial LTE and reuses the terrestrial LTE chipset as it is. It is necessary to simultaneously support both satellite and terrestrial terminals capable of realizing high quality services by optimizing the satellite environment by upgrading the terminal functions together with terrestrial terminals.

An object of the present invention is to provide an optimized service for satellite mobile communication by reducing the overhead of payload in a satellite mobile communication system while maintaining compatibility with terrestrial mobile communication.

In addition, another object of the present invention is to propose a downlink transmission method that is robust to nonlinearity of satellite power amplifier by lowering the PAPR, and to maintain the existing terrestrial LTE chipset by suggesting a communication method that maintains compatibility with the existing OFDM-based downlink transmission. It is to support both the terminal that can be reused and the low PAPR downlink reception.

Another object of the present invention is to economically improve the performance of a satellite mobile communication system by applying a downlink transmission method optimized for satellite mobile communication in a section in which a satellite / ground integrated mobile communication system does not transmit terrestrial mobile communication signals. It is.

In order to achieve the above object, the present invention includes the steps of selecting a frame by the terminal; And the terminal transmits the first downlink transmission method during the downlink transmission period of the terrestrial mobile communication signal in the frame, and lower than the first downlink transmission method during the period when the terrestrial mobile communication signal is not transmitted. There is provided a downlink transmission method in a terrestrial / satellite mobile communication integrated system, comprising: transmitting in a second downlink transmission method having a PAPR.

Preferably, the terrestrial mobile communication is characterized in that it is based on any one of LTE, WIMAX, satellite DMB, DVB-SH.

Preferably, the first downlink transmission scheme is an OFDM scheme, and the second downlink transmission scheme is a DFTS-OFDM scheme.

Preferably, the frame is a MBSFN sub-frame (MBMS Single Frequency Network, MBMSN).

Advantageously, the MBSFN subframe number to be transmitted in the second downlink transmission method is obtained by the terminal through a channel for broadcasting system information.

Preferably, the number of MBSFN subframe numbers to be transmitted in the second downlink transmission scheme is variable according to the required downlink transmission amount.

Advantageously, the DFTS-OFDM scheme comprises the steps of: mapping resources of a downlink shared channel (DL-SCH) to contiguous resource blocks (RBs); Mapping a reference signal (RS) to the mapped resource block (RB); Spreading data and the reference signal RS according to the number of subcarriers (Discrete Fourier Transform); And transmitting through an antenna after an IFFT is performed on the DFT spread signal.

In addition, the control unit for obtaining the downlink transmission information for each section of the frame from the base station through the physical broadcasting channel; And a period during which the terrestrial mobile communication signal is downlink transmitted in the frame according to the downlink transmission information for each section obtained from the control unit as a first downlink transmission method, and wherein the terrestrial mobile communication signal is not transmitted. In the meantime, there is provided a terrestrial / satellite mobile communication integrated terminal including a transceiver configured to recognize a second downlink transmission method having a lower PAPR than the first downlink transmission method.

Preferably, the terrestrial mobile communication is characterized in that it is based on any one of LTE, WIMAX, satellite DMB, DVB-SH.

Preferably, the first downlink transmission scheme is an OFDM scheme, and the second downlink transmission scheme is a DFTS-OFDM scheme.

Preferably, the predetermined frame is characterized in that the MBSFN (MBMS Single Frequency Network, MBSFN) sub-frame.

Preferably, the downlink transmission information for each section transmitted through the physical broadcasting channel includes at least one MBSFN subframe number and information indicating a downlink transmission scheme related thereto.

Preferably, the number of MBSFN subframes to be transmitted in the second downlink transmission scheme is variable according to the required downlink transmission amount.

Advantageously, the DFTS-OFDM scheme comprises the steps of: mapping resources of a downlink shared channel (DL-SCH) to contiguous resource blocks (RBs); Mapping a reference signal (RS) to the mapped resource block (RB); DFT spreading of data and the reference signal (RS) according to the number of subcarriers; And transmitting through an antenna after an IFFT is performed on the DFT spread signal.

Specific details of other embodiments are included in the detailed description and the drawings.

The present invention has the effect of supporting both the terminal to reuse the existing terrestrial LTE chipset as it is and the terminal capable of low PAPR downlink reception without collision.

In addition, the present invention has the effect of supporting the integration of satellite / terrestrial mobile communication system while minimizing the change of the existing mobile communication system more economically.

1 is a conceptual diagram of a satellite mobile communication system.

2 to 3 are diagrams illustrating a frame structure for simultaneously supporting a terrestrial mobile communication terminal and a terrestrial / satellite mobile communication terminal that support existing LTE and the like in an existing LTE frame using MBSFN while maintaining compatibility with the existing LTE; .

FIG. 4 is a flowchart illustrating a communication method for simultaneously supporting a terrestrial mobile communication terminal and a terrestrial / satellite mobile communication terminal that support existing LTE and the like in an existing LTE frame while maintaining compatibility with the existing LTE using MBSFN.

5 is a flowchart connected to A of FIG. 4.

6 is a downlink transport block diagram having a low PAPR according to an embodiment of the present invention.

7 is a flowchart of a downlink transmission communication method having a low PAPR according to an embodiment of the present invention.

In order to achieve the above object, in the present invention, existing LTE-based downlink transmission is performed in an LTE-based mobile communication system downlink which may cause performance degradation due to PAPR problem of multicarrier transmission due to nonlinearity of a power amplifier in a base station including a satellite. We propose a communication method for downlink transmission with low PAPR and backward compatibility.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a conceptual diagram of a satellite mobile communication system, and in the present invention, a communication method for low Peak to Average Power Ratio (PAPR) downlink transmission in a 3GPP LTE-based personal mobile satellite mobile communication system having the most common ground systems. Although described as a reference, the method of the present invention is a method such as repeater, CGC (Complementary Ground Component), ATC (Ancillary Terrestrial Component) such as Satellite DMB in Korea, Digital Video Broadcasting-Satellite services to Handhelds (DVB-SH) in Europe. It can be applied to any satellite connection standard based on OFDM, CDMA, WCDMA, TDMA, FDMA, etc. considered by 3GPP, 3GPP2, IEEE, etc. . In addition, the existing LTE wireless interface can be applied to the downlink of any mobile communication system that does not have the optimal performance in the downlink.

The system to which the present invention can be applied may consist of one or several GEO satellite groups, and each satellite is composed of a mono or multi-spot beam. Preferably, the location area of the terminal may be a spot, or in the case of a roaming user, may be a group of several spots. The satellite mobile terminal is connected to the network through one or several satellites directly connected to the gateway. In the system, the gateway considers either a centralized gateway or a group of geographically distributed gateways according to the operator's requirements.

Although not shown in FIG. 1, the gateway connects signals to a satellite base station, which is a network subsystem, and a satellite control station. Here, the satellite base station and the satellite control station have the same functions as the base station and the control station used in the ground network, and they exist inside or outside the gateway. Also, in order to maintain coverage in the shadow area where signal transmission is caused by buildings, mountains, etc. in the satellite environment, the system may use a ground assist device to amplify and transmit satellite signals by reusing the same frequency as satellites. Have

In the system structure of FIG. 1, broadcast or MBMS (Multimedia Broadcast / Multicast Service (MBMS)) services are provided through both satellite and ground assist devices. MBS services are provided through satellites in suburban and rural areas where Line of Sight is secured.In urban or indoor environments where satellite signals are not directly secured due to the large number of buildings or buildings, ground support equipment is provided. It will provide a broadcast service. Therefore, since the repeater does not provide voice and data communication services, only downlink transmission is generally considered, and when information for MBMS is needed, it is transmitted through the ground network. Secondly, in the case of voice and data communication services, it is almost impossible to provide communication services for all users in satellite beams with very large coverage with limited frequency resources. It provides voice and data services to only a small number of users in these uncovered areas.

However, when an uplink signal for voice and data communication or MBMS is required in an area where a satellite signal is not secured without being covered by the ground network as shown in FIG. 1, the ground assisting apparatus may transmit the uplink signal to the satellite. As shown in the system model of FIG. 1, in a region not covered by the terrestrial network, the terminal provides voice and data services through satellites and then receives a service through the terrestrial network with high transmission efficiency when it enters terrestrial network coverage. In this case, a handover occurs and the terminal should be able to receive both terrestrial and satellite network signals. However, if the terrestrial and satellite networks use heterogeneous specifications, the chip overhead of the terminal is large. Although not shown, an OFDM-based satellite radio interface is used which has the most commonity with the OFDM-based terrestrial 3GPP LTE radio interface. In addition, the satellite mobile communication system of FIG. 1 can increase data transmission capacity and improve reception performance by applying a multiple-input multiple-output (MIMO) technique using satellite multi-beam, two or more satellites, or antenna polarization. In addition, the spatial diversity gain for the slow-fading effect of satellites, which cannot be achieved through the conventional multi-antenna technique, is based on the cooperative communication using terrestrial assistants and the ad-hoc network configuration between terminals. You can get it through In addition, by applying techniques to efficiently use frequencies, the total system throughput can be improved.

As mentioned above, all of the personal portable satellite mobile systems considered in the future are serviced through satellites in rural or suburban areas where LoS is secured using ground assistive devices, and ground assisted devices in urban or indoor environments where satellite signals are not secured. Aim to provide. In addition, it is important to have commonality between the satellite and terrestrial wireless interfaces in order to reduce the chip set cost of the terminal. In other words, considering the current market situation in which the satellite mobile service cannot compete with the ground mobile service alone, and the ground network provides complementary service in the area or situation that the ground network cannot cover, It is expected that the initial satellite mobile service can preoccupy the initial market in a complementary relationship with the ground network when the wireless interface can maintain the most common with the ground network so that the satellite mobile service can be provided without upgrading the ground terminal. However, considering the commonality with the terrestrial network, the chip set cost of the terminal can be reduced, but the advanced technologies for satellite mobile services on the terminal side cannot be used. Required. This causes overhead on the satellite payload and results in limiting the overall satellite mobile system capacity. On the other hand, considering the commonality with the terrestrial network, the satellite mobile system can reduce the overhead of the satellite payload by using the transmission technology optimized for the satellite environment and implement the system optimized for the satellite mobile environment. have. However, in order for a terminal to use both satellite and terrestrial mobile communication services, the terminal must have a dual-mode chip for supporting satellite and terrestrial wireless interfaces. That is, there is a side that increases the overhead in the terminal side. In the case of this market approach, the initial satellite mobile service market, which cannot compete with the ground network, is expected to have difficulty in forming the initial market because it is expected that the ground terminal used by the ground service user does not want to be replaced. However, when the satellite mobile service market reaches a certain stage of growth, it is expected to increase system capacity by strengthening the system due to the increase in the total number of users and the demand for improving the service quality of the users of the satellite mobile service. In the above case, since the use of the wireless interface optimized for the satellite mobile environment will be required, the use of the wireless interface optimized for the satellite environment is expected to have more advantages.

In conclusion, in case of LTE-based satellite mobile communication system, it has commonality with terrestrial LTE and reuses terrestrial LTE chipset as it is, but performance deterioration can be achieved without additional cost. It is necessary to simultaneously support both satellite and terrestrial terminals that can be upgraded to optimize the satellite environment and realize high quality services.

Therefore, the present invention proposes a downlink transmission method that is robust to nonlinearity of a satellite power amplifier by lowering the PAPR, and a communication method that maintains compatibility with the existing OFDM-based downlink transmission. In other words, in the early market, the service is provided through a satellite wireless interface that has commonality with the terrestrial network for easy absorption of terrestrial users. In a mature market, the downlink transmission with low PAPR is supported simultaneously with the downlink transmission based on the existing LTE in order to increase the satellite system capacity.

In the proposed communication method, in the satellite wireless interface that has commonality with the terrestrial wireless interface, the existing wireless network interface within the frame structure of the satellite wireless interface was considered in the early market to use the communication technology optimized for the satellite environment without replacing the terminal and the system. A frame structure design is proposed to accommodate a user terminal having low PAPR downlink transmission without affecting a user using a wireless interface.

Hereinafter, a basic communication method for simultaneously supporting and supporting compatibility between a terrestrial mobile communication terminal supporting the existing LTE and the terrestrial / satellite mobile communication integrated terminal will be described. As described above, the terminal selects a frame and the terminal selects the frame. In the frame, a terrestrial mobile communication signal is transmitted in a first downlink transmission mode during downlink transmission, and in a section in which no terrestrial mobile communication signal is transmitted, it has a lower PAPR than the first downlink transmission method. Characterized in that the transmission in the second downlink transmission method.

In more detail, first, a channel or signal that broadcasts a portion including system information is transmitted including information for recognizing a section in which a user terminal using the downlink transmission scheme of the existing LTE cannot communicate. Existing user terminal using the downlink transmission method of LTE can obtain information on some sections or some frames of the frame not available to the existing terminal by first checking the system information upon initial access to the satellite system. Reference signals for channel estimation or control information in the section other than the interval are obtained. On the other hand, the terrestrial / satellite mobile communication integrated terminal of the present invention that supports low PAPR downlink transmission scheme may provide information on some sections or some frames of a frame that are not transmitted for a user terminal using the downlink transmission scheme of the existing LTE. Is obtained by acquiring the system information allocated in the existing wireless interface, and the advanced service and system capacity can be increased by performing low PAPR downlink transmission in the intervals. In the proposed frame structure, since the existing LTE signal is not transmitted in a transmission section that cannot be allocated to a user using the downlink transmission scheme of the existing LTE, a low PAPR downlink transmission is performed through the existing LTE signal. By transmitting without interference, the user terminal having low PAPR downlink transmission can be supported simultaneously with the existing LTE signal transmitting terminal while supporting the low PAPR downlink transmission flexibly without affecting the service of the existing terminal. .

Next, the present invention proposes a predetermined frame structure and a method of using the same for supporting a terrestrial mobile communication terminal and a terrestrial / satellite mobile communication integrated terminal while maintaining compatibility with the existing LTE.

In order to provide satellite service through the terrestrial terminal having the existing LTE signal transmission, the satellite wireless interface must apply the frame structure of the 3GPP LTE wireless interface without change. Therefore, the user terminal having the existing LTE signal transmission is provided with a communication service in the 3GPP LTE air interface frame structure. Next, when a user terminal having a low PAPR downlink transmission is considered in a satellite system, the user terminal having an existing LTE signal transmission supports the service according to a conventional communication method without recognition of the user terminal having a low PAPR downlink transmission. Should be. A user terminal having a low PAPR downlink transmission should support advanced services without affecting the existing LTE signal transmitting user terminal. To this end, we propose a method of using a subframe of a multimedia broadcasting and multicasting service single frequency network (MBSFN) supported by LTE. Here, MBSFN is an example for explaining the proposed frame and may have a different structure. LTE is a system for helping the understanding of the proposed invention, and other broadcasting and communication systems may be included. First, the characteristics of the MBSFN subframe of the existing LTE are as follows. Subframes 0, 4, 5, and 9 may not be used as MBSFNs because radio resource management (RMM) measurement and paging are performed using this subframe. In addition, one or two OFDM symbols are used for the control channel depending on the antenna configuration within the MBSFN subframe. That is, in the conventional LTE signal transmission, control channels such as common reference signal (CRS), physical control format indicator channel (PCFICH), physical hybrid-ARQ indicator channel (PHICH), and physical downlink control channel (PDCCH) have full bandwidth. It is compulsory to transmit in all sub-frames, and CRS estimates that all users use this signal to estimate the channel, and that the user terminal with low PAPR downlink transmission has a fixed transmission power. Consideration is essential when assigning to.

To this end, the satellite mobile system uses the same transmission frame as the existing LTE communication method only for a user terminal having the existing LTE signal transmission while using the existing LTE wireless interface frame structure in the early market. On the other hand, if there is a user who wants to receive advanced services or there is a demand for system capacity increase due to the increase in the number of users, satellite mobile communication is required to simultaneously support the user terminal having low PAPR downlink transmission with the existing LTE transmission. The system allocates MBSFN subframes in the existing LTE radio interface. MBSFN subframes that can be allocated by the satellite mobile system can be allocated in all subframes except subframes 0, 4, 5, and 9. The allocated subframe number may be known through a PBCH (Physical Broadcast Channel) broadcasting system information transmitted from an existing wireless interface, and the number of subframes allocated is low PAPR downlink transmission with a user terminal having existing LTE signal transmission. The branch can be flexibly allocated in the satellite system according to the capacity requirements between the user terminals. When the satellite mobile system allocates the MBSFN subframe, the user terminal having the existing LTE signal transmission does not acquire the MBSFN data recognized through the system information, and thus transmits and receives data through other subframes except the MBSFN. However, the user terminal having the existing LTE signal transmission can obtain the information of the control channel transmitted in the first one or two OFDM symbols of the MBSFN sub-frame, depending on the antenna configuration for uplink allocation grant (grant) information, Channel estimation may also be made through the CRS in the first one or two OFDM symbols of the MBSFN. However, subframes 0, 4, 5, and 9 cannot be used as subframes for MBSFN because CRS is mandatory for measurement and paging for RRM. On the other hand, in case of a user terminal having a low PAPR downlink signal transmission, the number of MBSFN subframes and the allocated subframe number are obtained through system information acquisition from a control channel such as a PBCH of a conventional radio interface. In the case of a user terminal having a low PAPR downlink signal transmission, data is transmitted and received only in the MBSFN subframe, and the first one or two OFDM symbols according to the antenna configuration in the MBSFN subframe are used to control the control channel and the CRS for the existing user terminal. Since the resource is used for low PAPR downlink signal transmission, it is possible to design a frame structure with low PAPR downlink signal transmission from the OFDM symbol.

In this way, the existing MBSFN subframe can be reused without modification without using the existing MBSFN subframe. However, the 0, 4, 5, and 9 subframes of the LTE radio interface cannot be used for MBSFN. Even when the number of user terminals having a PAPR downlink transmission increases, the subframes 0, 4, 5, and 9 may not be used, thereby limiting system capacity. To compensate for this, we propose a method of using the MBSFN subframe more flexibly according to the required downlink transmission variation by slightly modifying the frame structure of the terrestrial 3GPP LTE radio interface. As mentioned above, in case of a terminal having an existing LTE signal transmission, measurements for RRM are performed using CRSs of subframes 0 and 5, and subframes 0, 4, 5, and 9 are used for paging. In this case, when only the CRSs of subframes 0 and 5 are used for paging, a more flexible wireless interface transition can be made possible by increasing the number of subframes of MBSFN through possible small reduction in paging performance.

2 to 4 illustrate a frame structure for simultaneously supporting a terrestrial mobile communication terminal and a terrestrial / satellite mobile communication integrated terminal and supporting terrestrial / satellite mobile communication integrated terminals within the existing LTE frame using the MBSFN described above; Show the flow chart of the communication method.

In FIG. 2, subframes 1, 2, 3, 6, 7, and 8 are allocated as MBSFN subframes, and subframes 0, 4, 5, and 9 are allocated subframes for unicast for a terminal having existing LTE signal transmission. Show the case. In FIG. 3, subframes 1, 2, 3, 4, 6, 7, 8, and 9 are allocated as MBSFN subframes, and subframes 0 and 5 are allocated as subframes for unicast for a terminal having existing LTE signal transmission. Show the case. The number of subframes for MBSFN is flexibly determined according to the satellite system requirements. In addition, in the communication method flow chart of FIG. 4, a communication procedure procedure for simultaneously supporting a terminal having an existing LTE signal transmission and a user terminal having low PAPR downlink transmission may be appropriately changed.

Next, another second downlink transmission method having a PAPR lower than the first downlink transmission method used in terrestrial mobile communication such as LTE is proposed.

Many techniques for lowering PAPR in multicarrier based signal transmission have been proposed. However, the proposed techniques require modification of the existing LTE downlink transmission scheme such as adding pilot and feedback channel. Accordingly, the present invention proposes a downlink transmission scheme having a low PAPR while lowering the terminal chipset cost and maintaining compatibility with the existing LTE by reusing the existing LTE downlink transport block as it is.

Conventional LTE uses an OFDM downlink scheme, and the flow for transmission is as follows. The transport block to be transmitted on the downlink shared channel (DL-SCH) is attached with a CRC used for error detection at the receiving end, followed by turbo coding for error correction. In the case of spatial multiplexing, this process is performed twice for each transport block. Rate matching is controlled by HARQ (Hybrid Automatic Repeat reQuest (HARQ)) as well as the purpose of matching the number of encoded bits to fit the amount of resources allocated for downlink shared channel (DL-SCH) transmission. It is also used to create different redundancy versions. After rate matching, the encoded bits are modulated using Quadrature Phase-Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), 64QAM, and the like, and then mapped to an antenna. Antenna mapping may be configured to provide different multi-antenna transmission schemes including transmit diversity, beamforming, and spatial multiplexing. Finally, the output of the antenna processing is mapped to physical resources for the downlink shared channel (DL-SCH). The resources as well as the transport block size and modulation scheme are controlled by the scheduler. The signal mapped to the physical resource is transmitted through each antenna as an OFDM signal after the CP is inserted through the IFFT. In order to maintain compatibility with the existing LTE by reusing the existing LTE transport block and reduce the terminal chipset cost, the scheme of the OFDM downlink transport block of the existing LTE also mentioned in the downlink transmission having a low PAPR must be maintained. That is, the size of a transport block to be transmitted on a downlink shared channel (DL-SCH) should be the same as the existing LTE signal transmission, and the CRC attaching procedure, turbo coding method, rate matching method, resource mapping method, etc. must be the same as the existing LTE, and the order thereof is also identical. Should be.

6 and 7 show a communication method and a downlink transport block having a low PAPR in the present invention. To this end, the present invention adds a Discrete Fourier Transform (DFT) spreading step between the resource mapping and the IFFT while maintaining the existing LTE signal transmission block in order. As in uplink LTE, DFT spreading prior to IFFT allows multicarrier transmission to have a single carrier characteristic. In order to maintain compatibility with the existing LTE, the resource position of the signal to be transmitted in the existing LTE entering the IFFT and the signal position after the DFT spreading must be the same, and in order to maintain the single carrier characteristic, the DFT spreaded signal is continuously connected to the IFFT. Since the base station scheduler has to enter, the base station scheduler must sequentially allocate a resource block (RB) for mapping the data and the reference signal (RS). That is, there is a limit to flexible resource allocation in the frequency domain. However, in a mobile communication network having a frequency non-selective channel characteristic such as a satellite mobile communication network, resource allocation in the frequency domain has no significant gain, so even if the scheduler allocates each user data to consecutive resource blocks, there is almost no performance degradation. Therefore, the proposed low PAPR downlink transmission method has a CRC used for error detection at the receiving end of a transport block to be transmitted on a downlink shared channel (DL-SCH) according to the conventional LTE transmission scheme, and turbo coding for error correction. This follows. In the case of spatial multiplexing, this process is performed twice for each transport block. Rate matching is used not only to match the number of encoded bits to the amount of resources allocated for DL-SCH transmission, but also to create different redundancy versions controlled by HARQ. After rate matching, the coded bits are modulated using QPSK, 16QAM, 64QAM, etc., and then mapped to the antenna. Antenna mapping may be configured to provide different multi-antenna transmission schemes including transmit diversity, beamforming, and spatial multiplexing. Finally, the output of the antenna processing is mapped to physical resources for the downlink shared channel (DL-SCH). This physical resource mapping is allocated to the scheduler so that all DL shared channel (DL-SCH) resource mappings considered for downlink transmission are performed in consecutive resource blocks, and DL-SCH resource mapping is performed. Reference signal mapping is performed only in the resource block. Therefore, all data and reference signal mappings are seamlessly allocated to subcarriers, and Z-point DFT spreading is performed according to the number of resource blocks to which all data and reference signals are mapped, that is, the number of subcarriers Z required for data and reference signal allocation. The generated Z signals enter the position where the data before the DFT spreading and the reference signal are mapped to the N-point IFFT determined according to the signal bandwidth.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the devices and components described in the embodiments are, for example, processors, controllers, Arithmetic Logic Units (ALUs), Digital Signal Processors (Microcomputers), Microcomputers, Field Programmable Gate Arrays (FPGAs). Can be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device for the purpose of interpreting or providing instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims (14)

Selecting a frame by the terminal; And The terminal transmits the first downlink transmission method during the downlink transmission period of the terrestrial mobile communication signal in the frame, and has a lower PAPR than the first downlink transmission method during the period when the terrestrial mobile communication signal is not transmitted. And transmitting in a second downlink transmission method having a Peak to Average Power Ratio. The method of claim 1, The terrestrial mobile communication is a downlink transmission method in a terrestrial / satellite mobile communication integrated system, characterized in that based on any one of LTE, WIMAX, satellite DMB, DVB-SH. The method of claim 1, The first downlink transmission scheme is an OFDM scheme, and the second downlink transmission scheme is a Discrete Fourier Transform Spread-OFDM (DFTS-OFDM) scheme. . The method of claim 3, The frame is a downlink transmission method in a terrestrial / satellite mobile communication integrated system, characterized in that the MBSFN (MBMS Single Frequency Network) subframe. The method of claim 4, wherein MBSFN sub-frame number to be transmitted in the second downlink transmission method is a downlink transmission method in a terrestrial / satellite mobile communication integrated system, characterized in that the terminal is obtained through a channel for broadcasting system information. The method of claim 4, wherein The number of MBSFN sub-frame number to be transmitted in the second downlink transmission method is variable according to the required downlink transmission amount, characterized in that the downlink transmission method in the integrated terrestrial / satellite mobile communication system. The method of claim 3, The DFTS-OFDM scheme, Mapping resources of a downlink shared channel (DL-SCH) to consecutive resource blocks (RBs); Mapping a reference signal (RS) to the mapped resource block (RB); Spreading data and the reference signal RS according to the number of subcarriers (Discrete Fourier Transform); And And transmitting through the antenna after the IFFT is performed on the DFT spread signal. A control unit for obtaining downlink transmission information for each section of a frame from a base station through a physical broadcasting channel; And During the period in which the terrestrial mobile communication signal is downlink transmitted in the frame according to the downlink transmission information for each section obtained from the controller, the first downlink transmission method is recognized and during the period in which the terrestrial mobile communication signal is not transmitted. Is a terrestrial / satellite mobile communication integrated terminal comprising a transceiver configured to recognize a second downlink transmission method having a lower PAPR than the first downlink transmission method. The method of claim 8, The terrestrial mobile communication is a terrestrial / satellite mobile communication terminal, characterized in that based on any one of LTE, WIMAX, satellite DMB, DVB-SH. The method of claim 8, And the first downlink transmission method is an OFDM method, and the second downlink transmission method is a DFTS-OFDM method. The method of claim 10, And the predetermined frame is an MBSFN sub-frame of an MBSFN (MBC Single Frequency Network, MBSFN) subframe. The method of claim 11, The downlink transmission information for each section transmitted through the physical broadcasting channel includes at least one MBSFN subframe number and information indicating a downlink transmission scheme associated therewith. The method of claim 12, The number of MBSFN subframes to be transmitted in the second downlink transmission scheme is variable according to the amount of downlink transmission required. The method of claim 10 The DFTS-OFDM scheme, Mapping resources of a downlink shared channel (DL-SCH) to consecutive resource blocks (RBs); Mapping a reference signal (RS) to the mapped resource block (RB); DFT spreading of data and the reference signal (RS) according to the number of subcarriers; And And after the IFFT is performed on the DFT spread signal, transmitting the antenna through an antenna.

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