WO2017126897A1

WO2017126897A1 - Method and transmission apparatus for multiple access in wireless communication system

Info

Publication number: WO2017126897A1
Application number: PCT/KR2017/000638
Authority: WO
Inventors: 김광순; 김종현
Original assignee: 연세대학교 산학협력단
Priority date: 2016-01-19
Filing date: 2017-01-19
Publication date: 2017-07-27

Abstract

Disclosed are multiple access method and apparatus capable of providing a service having minimum latency and high reliability and high throughput in a wireless communication system. The multiple access method according to the present invention comprises the steps of: allocating resources for a plurality of user terminals by space and frequency; carrying out discrete Fourier transforms, for each space, of transmission symbols which comprise a plurality of sub-symbols and which are transmitted in accordance with the allocated space and frequency resource; and applying frequency and space filters to the results of the Fourier transforms, wherein the step for applying frequency and space filters selects, for each space, a pulse-shaping filter in accordance with the location of the allocated frequency resource, and applies the selected pulse-shaping filter to the sample which is a result of a sub-symbol Fourier transformed into a frequency domain.

Description

Multiple access method and transmission device for multiple access in wireless communication system

The present invention relates to a multiple access method and a transmission apparatus for multiple access in a wireless communication system, and more particularly, to a multiple access method and multiple access in a wireless communication system capable of providing ultra low delay, high reliability, and high capacity services. It relates to a transmission device for.

As various researches on 5G (5th generation) mobile communication are conducted through various research institutes, services that are expected to emerge in the future are being specified, and requirements for supporting such services are also summarized. As a new service category of 5G mobile communication, ultra low latency high reliability high capacity service requires a wireless section delay time of less than 1ms, a reliability condition of 99.999%, and a data transmission capacity of up to 100Mbps.

In order to achieve the above service conditions, the following requirements must be satisfied. Each user needs a waveform configuration that is suitable for different mobility and channel environments, and the various waveforms configured in this way must coexist efficiently. If multiple antennas are used at the transceiver, three-dimensional waveform configuration of time, frequency, and space can be made for each user's characteristics. Therefore, it is necessary to provide the required reliability by reducing interference between waveforms and increasing diversity. do. Non-orthogonal multiple access schemes may be used for resources allocated to time, frequency, and space, and non-orthogonality may change according to time or channel environment.

Currently, IMT-Advanced, a commercial mobile communication system, uses Orthogonal Frequency Division Multiplexing (OFDM) waveforms. OFDM waveforms can solve multipath fading using cyclic prefix (CP), and can implement waveform modulation with low complexity through fast Fourier transform. Have. However, because OFDM waveforms have a large out-of-band emission in a non-orthogonal situation, when used with waveforms having different parameters, interference occurs and is inefficient. The disadvantage is that it must be used as a form.

5G mobile communication research institutes, telecommunication operators, and manufacturers have proposed multicarrier waveforms using filters to improve the shortcomings of the OFDM waveform. METIS-II, a project undertaken by 5GPPP, an alliance for developing 5G technology, considers FBMC (Filter-Bank Multi-Carrier modulation) waveform as a radio interface. In addition, GFDM (Generalized Frequency Division Multiplexing) and UFMC (Universal Filtered) Multi-Carrier) and f-OFDM (filtered-OFDM) have been studied.

As such, the multicarrier waveform using the filter is more asynchronous than the OFDM waveform, and even when the waveform parameters are different, the waveforms can coexist efficiently without affecting interference.

The present invention is to provide a multiple access method and a transmission device for multiple access in a wireless communication system capable of providing ultra low delay, high reliability and high capacity services.

According to an embodiment of the present invention to achieve the above object, the step of allocating resources for a plurality of user terminals, space and frequency; Performing discrete Fourier transform on the basis of a plurality of sub-symbols and performing transmission symbols transmitted according to the allocated spatial and frequency resources in units of spaces; And applying a frequency filter and a spatial filter to the Fourier transform result, wherein applying the frequency filter and the spatial filter comprises applying a pulse shaping filter to the spatial unit in accordance with an arrangement position of the allocated frequency resource. Optionally, a multiple access method is provided in a wireless communication system that applies a selected pulse shaping filter to a sample that is the result of Fourier transforming the sub-symbols into a frequency domain.

In addition, according to another embodiment of the present invention to achieve the above object, the step of allocating resources for a plurality of user terminals, space and frequency; Performing discrete Fourier transform on the basis of a plurality of sub-symbols and performing transmission symbols transmitted according to the allocated spatial and frequency resources in units of spaces; And applying a frequency filter and a spatial filter to a sample resulting from the Fourier transform of the sub-symbols in the frequency domain, wherein the frequency filter comprises a frequency equalization filter and a pulse shaping filter. This is provided.

In addition, according to another embodiment of the present invention to achieve the above object, a resource allocator for allocating resources for a plurality of user terminals, space and frequency; A Fourier transform unit comprising a plurality of sub-symbols, and performing a discrete Fourier transform on the spatial units of the transmission symbols transmitted according to the allocated spatial and frequency resources; And a filtering unit for selecting a pulse shaping filter according to an arrangement position of the allocated frequency resource and applying the selected pulse shaping filter to a sample that is a result of Fourier transform of the sub-symbols in the frequency domain. A transmission apparatus for multiple access in a communication system is provided.

According to the present invention, the interference between subcarriers can be reduced by selecting and using the pulse shaping filter according to the arrangement position of resources allocated for each frequency, without using a fixed pulse shaping filter.

In addition, according to the present invention, by applying a frequency filter and a spatial filter on a sample basis, it is possible to provide high beamforming resolution and excellent out-of-band channel performance.

1 and 2 are diagrams for explaining the GFDM.

3 is a diagram illustrating an allocation map of a resource block according to an embodiment of the present invention.

4 and 5 are diagrams illustrating filtered subcarriers according to the resource block allocation map of FIG. 3.

FIG. 6 is a diagram for describing spatial multiplexing access according to the resource block allocation map of FIG. 3.

7 is a view for explaining a transmission system according to an embodiment of the present invention.

8 is a view for explaining a receiving system according to an embodiment of the present invention.

9 is a diagram illustrating a transmission device for multiple access according to an embodiment of the present invention.

10 is a diagram illustrating a multiple access method according to an embodiment of the present invention.

11 is a diagram showing throughput and throughput simulation results of GFDM and OFDM according to the present invention.

12 is a diagram illustrating a pseudo-code for explaining a multiple access method according to another embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

The present invention proposes a new method of multiple access in a wireless communication system. In the present specification, the multiple access method according to the present invention will be referred to as Universal Spatio-Frequency Division Multiple Access (USFDMA).

The multiple access method according to the present invention provides high beamforming resolution and good out-of-band channel performance under ultra low delay, high reliability, and high capacity service requirements, and exhibits higher frequency efficiency than GFDM and OFDM.

Hereinafter, after briefly reviewing the GFDM, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are diagrams for explaining the GFDM.

When GFDM transmits N = KM data, the GFDM transmits data in the form of a data block including K subcarriers and M subsymbols, as shown in FIG. 1. Compared to the OFDM data block shown in FIG. 2, the data block of the GFDM shown in FIG. 1 includes one transmission symbol composed of a plurality of subsymbols, and one subcarrier transmits a plurality of subsymbols in the GFDM. Form.

All data to be sent in the GFDM is modulated by the GFDM transmission matrix A and then added with a Cyclic Prefix (CP) to minimize the effect of delay spread of the channel and remove the inter-block interference of the GFDM, such as OFDM.

When the data to be transmitted is constant as N = KM, if the number of subsymbols increases, the spacing of subcarriers increases. At this time, if the channel has a frequency selective characteristic, magnetic interference cannot be eliminated, and thus the performance of the GFDM is reduced. However, if the FFT size of GFDM is increased by M times than the existing FFT size, M samples can be included between the same subcarrier spacings, so that the frequency resolution is increased and performance is not significantly reduced even in a frequency selective channel.

The GFDM uses a pulse shaping filter fixed in the frequency domain to perform filtering on a sample that is a result of frequency conversion of a subsymbol. Frequency equalization filtering and spatial filtering are performed in units of transmission symbols.

Non-orthogonal waveforms generated by pulse shaping filtering in GFDM cause subcarrier interference to increase BER.

Accordingly, the present invention proposes a multiple access method capable of satisfying ultra low delay, high reliability, and high capacity service requirements by reducing interference between subcarriers.

In the multiple access method according to the present invention, the interference between subcarriers can be reduced by selecting and using a pulse shaping filter according to an arrangement position of resources allocated for each frequency, without using a fixed pulse shaping filter.

In addition, the multiple access method according to the present invention can provide high beamforming resolution and excellent out-of-band channel performance by applying a frequency filter and a spatial filter on a sample basis.

The multiple access method according to the present invention may be performed in a transmission apparatus for multiple access, and the transmission apparatus may be a base station.

3 illustrates an allocation map of a resource block according to an embodiment of the present invention, and FIGS. 4 and 5 illustrate filtered subcarriers according to the resource block allocation map of FIG. 3. 6 is a diagram for describing a spatial multiplexing connection according to the resource block allocation map of FIG. 3.

In FIG. 3, a case in which four subcarriers and four substreams are allocated to four user terminals is described as an embodiment. However, resource allocation may be variously performed according to an embodiment.

The base station according to the present invention allocates spatial and frequency resources for each user terminal as shown in FIG. 3 in consideration of resource conditions, channel conditions, service requirements, and the like. The subcarrier corresponds to the frequency resource and the substream corresponds to the spatial resource.

For example, data for the first user terminal user1 is transmitted through the first to

third subcarriers

301, 302, and 303, and simultaneously through the first and second substreams 311 and 312. do. The data for the fourth user terminal user4 is transmitted through the fourth subcarrier 304 and simultaneously transmitted through the first to

fourth substreams

311, 312, 313, and 314.

The base station transmits a transmission symbol to a user terminal according to the allocated resource, the transmission symbol is composed of a plurality of sub-symbols. The base station performs a discrete Fourier transform for each spatial unit, that is, for each substream, and the sub-symbols are represented by different frequency components in the frequency domain according to the Fourier transform.

The base station selects, in spatial units, the pulse shaping filter according to the placement position of the allocated frequency resource, and applies the selected pulse shaping filter to the sample resulting from Fourier transform of the sub-symbols into the frequency domain. The discrete Fourier transform is an M-point Fast Fourier Transform (FFT), which represents different frequency components for each subsymbol as a result of the Fourier transform, and M corresponds to the number of subsymbols.

Referring to FIG. 4 illustrating the subcarriers filtered for each substream, it can be seen that four pulse shaping filters are applied. The filtered subcarriers of FIG. 4 are expressed for one sample group in which filtering is performed at the same time. Since a plurality of sub symbols are transmitted through one subcarrier, pulse shaping filtering is performed on the plurality of sample groups, respectively. .

That is, as shown in FIG. 5 in which the filtered subcarrier of FIG. 4 is represented in the time-space-frequency domain, each subsymbol in the time-space-frequency domain corresponds to a symbol duration in the time domain. Samples are generated in the frequency domain for each subsymbol for, and pulse shaping filtering is performed for each sample group.

The pulse shaping filter is selected from a Square-Root Raised Cosine (SRRC) filter 440, a left-squeezed SRRC filter 410, a right-squeezed SRRC filter 430, and a square filter 420. The pulse shaping filter may be selected depending on whether the allocation index of the frequency resources for the same user terminal is continuous.

4 and 5, the frequency response of the SRRC filter 440 is trapezoidal, and the frequency response of the rectangular filter 420 is rectangular. In comparison with the SRRC filter 440, the frequency response of the left squeeze SRRC filter 410 has a rectangular shape on the right side, and the frequency response of the light squeeze SRRC filter 430 has a square shape on the left side.

The base station performs pulse shaping filtering on the samples in the order of left squeeze SRRC filter and light squeeze SRRC filter when the allocation index of the frequency resource for the same user terminal is continuous, and when the number of consecutive allocation indexes is 3 or more, Pulse shaping filtering may be performed on the sample by placing at least one square filter between the squeeze SRRC filter and the light squeeze SRRC filter.

In FIG. 3, the allocation indexes may be allocated in order from the first subcarrier to the fourth subcarrier. Referring to FIG. 3, since the frequency resources for the first user terminal, that is, the subcarriers are sequentially allocated, are applied to the samples in the order of left squeeze SRRC filter 410 and light squeeze SRRC filter 430, three subcarriers are applied. Since are allocated consecutively, the square filter 420 is disposed between the left squeeze SRRC filter 410 and the light squeeze SRRC filter 430. If four subcarriers are sequentially allocated to the first user terminal, two rectangular filters may be disposed between the left squeeze SRRC filter and the right squeeze SRRC filter.

Since two subcarriers are sequentially allocated to the third user terminal, the left squeeze SRRC filter 410 and the light squeeze SRRC filter 430 are sequentially applied to the sample without the quadrangle filter 420.

If the allocation index of frequency resources for the same user terminal is not continuous, the base station performs pulse shaping filtering on the sample using the SRRC filter. In FIG. 3, since only one subcarrier for the fourth user terminal is allocated for each substream and is not continuous, the SRRC filter 440 is applied to the fourth user terminal as shown in FIG. 4.

As such, the filtered signal in the frequency domain is transmitted to the user terminal through different substreams, as shown in FIG. 6. 6 (a) to 6 (b) show first to fourth substreams transmitted through the first to fourth subcarriers, respectively.

Symbols for the first and second user terminals to which the first subcarrier is allocated are transmitted to the first and second user terminals through the first to fourth substreams as shown in FIG. Referring to FIG. 3, symbols for a first user terminal are transmitted through first and second substreams each having different beams, and symbols for the second user terminal are each formed with different beams. And a fourth substream.

Likewise, the symbols to which each subcarrier is allocated are transmitted to the user terminal through the first to fourth substreams, as shown in FIGS. 6 (b) to 6 (d).

Meanwhile, the base station performs filter shaping filtering, and may perform frequency equalization filtering and spatial filtering together. Frequency equalization filtering and spatial filtering are also performed on a sample basis, and the frequency equalization filter and the spatial filter may be determined according to channel conditions for each user terminal.

7 is a view for explaining a transmission system according to an embodiment of the present invention, Figure 8 is a view for explaining a reception system according to an embodiment of the present invention.

FIG. 7 illustrates a series of transmission processing procedures performed at a base station. In FIG. 7, a case in which resource blocks are allocated as shown in FIG. 3 will be described as an embodiment. 8 illustrates a series of reception processing procedures performed in a user terminal, and in FIG. 8, a reception system for a first user terminal is described as an embodiment.

The base station according to the present invention arranges the data block according to the allocated resource as shown in FIG. 3 (710). That is, data blocks consisting of M sub-symbols are arranged according to subcarriers and substreams allocated for each user terminal. The data block corresponds to the above-described transmission symbol.

The sub-symbol allocated to each block may be QAM data as an embodiment, and may be represented by a vector as shown in [Equation 1]. Alternatively, different modulation schemes may be applied for each subsymbol according to an embodiment, and each subsymbol may be data according to at least one modulation scheme.

Here, u represents the index of the data block, k represents the index of the subcarrier, and l represents the index of the substream. For example, u for the data block 711 may be 4, k may be 4, and l may be 1. .

The base station performs 720 an M-point FFT in units of space, that is, in units of substreams. The Fourier transform result is arranged for each subcarrier index for one substream, and the Fourier transform result for each substream is arranged for each substream index (730).

As a result of the M-point FFT, a frequency domain signal is generated for each data block, and the frequency domain signal may be expressed as shown in [Equation 2].

Here, i represents an index for the user terminal,

Represents the M-point DFT matrix.

silver

Represents the l-th column of the identity matrix of size,

to be.

Denotes the Kronecker product operator.

The base station multiplies (740) a power allocation parameter (Q) for compensating for the attenuation of the effective channel for the frequency domain signal for each substream, and the sample is the result of Fourier transforming the sub-symbols into the frequency domain. Filtering is performed (750). The power allocation parameter Q is described in more detail in FIG. 12.

More specifically, the base station is a frequency filter (frequecy filter,

) And spatial filters,

Filtering is performed on a per-sample basis. The frequency filter is a frequency domain equalizer (frequecy domain equalizer,

) And pulse shaping filter

).

The base station selects a pulse shaping filter according to an arrangement position of frequency resources allocated to a user terminal, that is, an allocation index of a subcarrier, in space units, and may select one of the four filters described above. Pulse shaping filtering is performed on the samples in units of substreams using the selected filter.

In this case, the base station may perform frequency equalization filtering and pulse shaping filtering together with the pulse shaping filtering on a sample basis. The base station determines the frequency equalization filter and the spatial filter according to the channel state between user terminals, and may determine the frequency equalization filter and the spatial filter in consideration of the channel state for each duration of the subsymbol. In particular, the base station may determine the spatial filter in consideration of the channel status for each substream, and the spatial filter is a filter for beamforming as a filter for precoding.

Thereafter, the base station performs an MK-point IFFT to convert a signal in the frequency domain into a signal in the time domain (760), inserts a CP or CS (Cyclic Suffix) according to the channel state, and transmits the signal to the user terminal (770). do.

The signal in the time domain can be obtained using [Equation 3].

here,

Represents the Hadamard product operator,

Represents an IDFT matrix. N _UE is the number of user terminals,

Denotes a power allocation parameter.

That is, filtering may be performed by multiplying the frequency filter vector and the spatial filter vector for all samples MK in the frequency domain.

Meanwhile, since IFFT and CP or CS insertion may be performed in the same manner as GFDM, a detailed description thereof will be omitted.

As such, the signal converted into the time domain is transmitted to the user terminal, and the user terminal may recover the QAM data symbol from the received signal as shown in FIG. 8. The processing of the received signal proceeds in the reverse order of the processing of the transmission signal.

Referring to FIG. 8, which illustrates a procedure for processing a received signal for a first user terminal, first, a first user terminal removes 810 a CP or a CS from a received signal Y _u . After performing the MK-point FFT (820), the frequency filter in the frequency domain (

) And spatial filter (

) Demodulates the frequency domain signal (830). The M-point IFFT is performed to restore the QAM data symbols in the time domain (840).

Frequency filter is pulse shaping filter (

) And frequency equalization filter (

The filtering process is the same as that of the transmission signal.

The transmission apparatus according to the present invention includes a resource allocator 910, a Fourier transform unit 920, and a filtering unit 930.

The resource allocator 910 allocates resources for a plurality of user terminals by space and frequency, and may allocate them as shown in FIG. 3 as an embodiment.

The Fourier transform unit 920 is composed of a plurality of sub-symbols and performs discrete Fourier transform on a space unit with respect to transmission symbols transmitted according to the allocated space and frequency resources.

The filtering unit 930 selects a pulse shaping filter according to an arrangement position of allocated frequency resources in spatial units, i.e., in a substream unit, and selects a pulse shaping filter selected for a sample that is a result of Fourier transform of a sub-symbol into a frequency domain. Apply.

The filtering unit 930 performs precoding on each sample, and according to an embodiment, may include a frequency filtering unit and a spatial filtering unit.

The frequency filter performs filtering on the sample using a pulse shaping filter and a frequency equalization filter. Filtering may be performed by multiplying the frequency response of each sample and the pulse shaping filter, the frequency response of the frequency equalization filter in the frequency domain. The spatial filter also performs filtering on a sample basis.

The samples precoded by the filtering unit 930 are converted into signals in the time domain and then transmitted to the user terminal.

Pulse shaping filtering may be performed as described in FIGS. 3 to 7.

Meanwhile, the transmission apparatus according to the present invention is characterized in that frequency equalization filtering and spatial filtering are performed on a sample basis as compared with GFDM which performs frequency equalization filtering and spatial filtering on a transmission symbol basis. Detailed description of the filtering will be omitted.

FIG. 10 is a diagram illustrating a multiple access method according to an embodiment of the present invention. In FIG. 10, the multiple access method of the above-described transmission apparatus is described as an embodiment.

The transmission apparatus according to the present invention allocates resources for a plurality of user terminals by space and frequency (S1010). In operation S1020, a Discrete Fourier Transform is performed for each transmission symbol that is composed of a plurality of sub-symbols and is transmitted according to the allocated spatial and frequency resources. Here, the discrete Fourier transform is an M-point FFT, where M corresponds to the number of sub-symbols. The modulation scheme is determined for each sub symbol, and the sub symbol may be, for example, a QAM data symbol.

Thereafter, the transmitting device may apply a frequency filter and a spatial filter to the Fourier transform result, and apply the frequency filter and the spatial filter to the sample that is the result of the Fourier transform of the sub-symbol into the frequency domain. The frequency filter includes a pulse shaping filter and a frequency equalization filter.

More specifically, the transmitting apparatus selects a pulse shaping filter according to the arrangement position of the allocated frequency resource in units of space, and applies the selected pulse shaping filter to the sample resulting from Fourier transform of the sub-symbols in the frequency domain (S1030). do. The transmission device may select a pulse shaping filter from an SRRC filter, a left squeeze SRRC filter, a light squeeze SRRC filter, and a square filter.

The transmitting device may apply the frequency equalization filter and the spatial filter according to the channel state of the user terminal to the sample. In this case, the modulation index and the spatial filter may be simultaneously determined so that the power for the transmission symbol is minimized.

Meanwhile, the transmission apparatus according to the present invention may determine the frequency, the spatial filter and the modulation index to minimize the transmission power, which will be described in detail with reference to FIG. 12.

FIG. 11 assumes that each user belongs to a Rayleigh fading channel environment having the same distance attenuation from one base station, and is divided in half into users having high mobility (500 km / s) and low mobility (0 km / s). In order to prevent Doppler fading, a simulation result in a condition in which USFDMA and GFDM coexist with waveforms having different symbol lengths according to mobility is shown. Since OFDM symbols of different lengths cannot coexist due to low out-of-band (OOB) performance, the experiments are divided into long symbols (OFDM Long) and short symbols (OFDM Short). In the simulation, the center frequency is 5Ghz, the bandwidth is 80MHz, and the interval between subcarriers is 16.875KHz. The long symbol uses 8192 FFT size and the short symbol uses 1024 FFT size.

Since OFDM and GFDM use symbol-level beamforming, and USFDMA uses sample-level beamforming, USFDMA has higher beamforming performance than GFDM, and data transfer capacity performance is higher under given conditions than OFDM due to mobility coexistence waveform coexistence. It can be seen.

In FIG. 12, a method for minimizing power required for transmitting a transmission symbol while satisfying a data transmission capacity condition and a reliability condition required for a mobile communication service is described. The present invention provides a space-frequency filter so that minimum transmission power can be used while satisfying data transmission capacity conditions and reliability conditions.

) And a modulation index.

The space-frequency filter is a precoder, and according to the space-frequency filter determined by the present invention, the transmission symbols are precoded and transmitted to the user terminal, and bits allocated to frequency-spatial resources by the modulation index determined by the present invention. The number is determined. The modulation index is a parameter indicating how many bits can be stored per symbol and indicates the number of bits allocated to frequency-space resources (k, l).

The transmission apparatus according to the present invention first determines the space-frequency filter so that the reliability condition according to the modulation index pre-assigned for each space-frequency resource is satisfied, and at the same time, data can be transmitted with the minimum transmission power. As shown in Equation 4, a space-frequency filter may be determined. Here, the transmission power P corresponds to the power allocation parameter Q described above.

Whether the reliability condition according to the modulation index is satisfied may be calculated using SINR. Reliability conditions (

Calculated than SINR (

If) is large, it can be determined that the reliability condition is satisfied. Since the data to be transmitted is determined according to the modulation index, and the noise may be determined according to the channel state with the user terminal, the SINR to be compared with the reliability condition may be calculated. At this time, since the SINR is also determined according to the space-frequency filter, the transmission apparatus according to the present invention calculates the SINR and the transmission power for various space-frequency filters, satisfying the reliability conditions and simultaneously using the minimum power. The frequency filter can be determined.

Since the SINR may be increased as the transmission power is increased, a space-frequency filter corresponding to the minimum transmission power that satisfies the reliability condition may be determined as the solution of Equation 4.

In FIG. 7, it is described that the spatial-frequency filter may be determined according to the channel state. According to the embodiment, the transmitting device may determine the spatial-frequency filter capable of minimizing the transmission power while considering the channel state.

In addition, transmitting device space according to the invention meet the user terminal by data transmission capacity conditions in the effective channel is determined by the combination of the frequency filter (b _i) - space for frequency resource-frequency when the filter is given, channels, and spaces At the same time, the modulation index is determined for each space-frequency resource so that the transmission symbol can be transmitted with the minimum power.

As an example, the transmission apparatus according to the present invention may determine a modulation index for each space-frequency resource, as shown in [Equation 5].

The transmission apparatus according to the present invention may determine whether the data transmission capacity condition for each user terminal is satisfied while increasing the modulation index by one from the initial value. As the modulation index increases, the rate increases, which may increase the likelihood that the data transmission capacity condition is satisfied.

At this time, the transmission apparatus determines a modulation index such that the data transmission capacity condition is satisfied in the effective channel according to the determined space-frequency filter as described above, and simultaneously determines the modulation index so that the transmission symbol can be transmitted at the minimum power. do.

As a result, the transmission apparatus according to the present invention can determine the spatial-frequency filter and the modulation index satisfying the equations (4) and (5) at the same time.

In other words, the transmission apparatus according to the present invention determines a frequency filter and a spatial filter that minimize transmission power by using a preset modulation index for frequency and spatial resources, and uses the frequency filter and spatial filter determined as described above. For example, the modulation index may be updated to minimize the transmission power. The updated modulation index can then be used to determine the space-frequency filter.

Meanwhile, according to the present invention, since the frequency filter and the spatial filter are applied for each sample, the spatial-frequency filter and the modulation index may be differently determined for each subsymbol, and thus different transmission powers may be allocated and transmitted for each subsymbol. have.

A method of determining the above-described spatial-frequency filter and modulation index is represented by a pseudo code as shown in FIG. 12.

The technical contents described above may be embodied in the form of program instructions that may be executed by various computer means and may be recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. 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 may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

Claims

Allocating resources for a plurality of user terminals by space and frequency;

Performing discrete Fourier transform on the basis of a plurality of sub-symbols and performing transmission symbols transmitted according to the allocated spatial and frequency resources in units of spaces; And

Applying a frequency filter and a spatial filter to the Fourier transform result;

Applying the frequency filter and the spatial filter

Selecting the pulse shaping filter according to the arrangement position of the allocated frequency resource in the spatial unit, and applying the selected pulse shaping filter to a sample that is a result of Fourier transforming of the sub-symbols in the frequency domain

Multiple access method in wireless communication system.
The method of claim 1,

Applying the frequency filter and the spatial filter

Selecting pulse shaping filters from SRRC filters, left-squeezed SRRC filters, right-squeezed SRRC filters, and square filters

Multiple access method in wireless communication system.
The method of claim 2,

Applying the frequency filter and the spatial filter

When the allocation index of frequency resources for the same user terminal is continuous, the pulse shaping filtering is performed on the samples in the order of left squeeze SRRC filter and light squeeze SRRC filter.

Multiple access method in wireless communication system.
The method of claim 3, wherein

Applying the frequency filter and the spatial filter

When the number of consecutive allocation indices is 3 or more, at least one rectangular filter is disposed between the left squeeze SRRC filter and the light squeeze SRRC filter to perform pulse shaping filtering on the sample.

Multiple access method in wireless communication system.
The method of claim 2,

Applying the frequency filter and the spatial filter

When the allocation index of the frequency resource for the same user terminal is not continuous, performing pulse shaping filtering on the sample using the SRRC filter

Multiple access method in wireless communication system.
The method of claim 1,

Applying the frequency filter and the spatial filter

Applying a frequency equalization filter to the sample according to channel conditions for the user terminal; And

Applying a spatial filter to the sample according to channel conditions for the user terminal

Multiple access method in a wireless communication system comprising a.
The method of claim 1,

The Discrete Fourier Transform

M-point FFT,

M corresponds to the number of sub-symbols

Multiple access method in wireless communication system.
The method of claim 1,

The modulation method is determined for each sub-symbol,

The modulation index and the spatial filter are determined simultaneously so that the power for the transmitted symbol is minimal

Multiple access method in wireless communication system.
The method of claim 8,

The sub symbol is

QAM data

Multiple access method in wireless communication system.
Allocating resources for a plurality of user terminals by space and frequency;

Performing discrete Fourier transform on the basis of a plurality of sub-symbols and performing transmission symbols transmitted according to the allocated spatial and frequency resources in units of spaces; And

Applying a frequency filter and a spatial filter to a sample resulting from the Fourier transform of the sub-symbols in the frequency domain,

The frequency filter includes a frequency equalization filter and a pulse shaping filter.

Multiple access method in wireless communication system.
The method of claim 10,

Applying the frequency filter and the spatial filter

Selecting a pulse shaping filter according to the arrangement position of the allocated frequency resource, and applying the selected pulse shaping filter for the sample on the spatial basis;

Applying a frequency equalization filter to the sample according to channel conditions for the user terminal; And

Applying a spatial filter to the sample according to channel conditions for the user terminal

Multiple access method in a wireless communication system comprising a.
The method of claim 10,

Determining the spatial filter that minimizes transmission power by using a preset modulation index for the frequency and spatial resources; And

Using the spatial filter, updating the modulation index to minimize the transmit power

Multiple access method in a wireless communication system comprising a.
A resource allocator for allocating resources for a plurality of user terminals by space and frequency;

A Fourier transform unit comprising a plurality of sub-symbols, and performing a discrete Fourier transform on the spatial units of the transmission symbols transmitted according to the allocated spatial and frequency resources; And

A filtering unit that selects a pulse shaping filter according to the arrangement position of the allocated frequency resources and applies the selected pulse shaping filter to a sample that is a result of Fourier transforming the sub-symbols in the frequency domain in the spatial unit

Transmission apparatus for multiple access in a wireless communication system comprising a.
The method of claim 13,

The filtering unit

A frequency filter configured to perform filtering on the sample using the pulse shaping filter and the frequency equalization filter; And

A spatial filter for filtering the sample using a spatial filter

Transmission apparatus for multiple access in a wireless communication system comprising a.
The method of claim 13,

The filtering unit

Selecting pulse shaping filters from SRRC filters, left-squeezed SRRC filters, right-squeezed SRRC filters, and square filters

Transmission apparatus for multiple access in a wireless communication system.
The method of claim 15,

The filtering unit

When the allocation index of the frequency resource for the same user terminal is continuous, pulse shaping filtering is performed on the samples in the order of left squeeze SRRC filter and light squeeze SRRC filter,

When the number of consecutive allocation indices is 3 or more, at least one rectangular filter is disposed between the left squeeze SRRC filter and the light squeeze SRRC filter to perform pulse shaping filtering on the sample.

Transmission apparatus for multiple access in a wireless communication system.