Patent Description:
However, the frame structure of the existing Long-Term Evolution (LTE) and LTE-Advanced (LTE-A) systems is designed considering normal voice/data communications, and has limitations in scalability for various services and requirements like those of a <NUM> system.

<NPL>) provides an analysis and comparison on numerology candidates as regards to impact on scalability, frame structure, and legacy coexistence.

<NPL>) discusses agreements for NR numerology.

<NPL>) discusses various numerology and frame structure which may be determined based on deployment scenarios and usage scenarios.

Therefore, a need exists for a flexible frame structure for use in a <NUM> system considering various services and requirements.

The present disclosure is designed to address at least the problems and/or disadvantages described above and to provide at least the advantages described below.

Accordingly, an aspect of the present disclosure is to provide an efficient scalable frame structure for integrating and supporting various services in a mobile communication system and provision of a method and an apparatus for using the same.

Another aspect of the present disclosure is to provide a scalable frame structure that minimizes inter-symbol interference, thereby improving the system performance.

Preferred embodiments of the invention are matter of the dependent claims.

According to an aspect of the present disclosure, it is provided that an efficient scalable frame structure for integrating and supporting various services in a mobile communication system and provision of a method and an apparatus for using the same. Therefore, system performance is enhanced by minimizing interference between symbols.

The above and other aspects, features, and advantages of certain embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:.

Various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, specific details such as detailed configurations and components are merely provided to assist the overall understanding of these embodiments of the present disclosure. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein can be made without departing from the scope of the present disclosure as defined by the appended claims. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

In each drawing, the same or similar components may be denoted by the same reference numerals.

Each block of the flow charts and combinations of the flow charts may be performed by computer program instructions. Because these computer program instructions may be mounted in processors for a general computer, a special computer, or other programmable data processing apparatuses, these instructions executed by the processors for the computer or the other programmable data processing apparatuses create means performing functions described in block(s) of the flow charts. Because these computer program instructions may also be stored in a computer usable or computer readable memory of a computer or other programmable data processing apparatuses in order to implement the functions in a specific scheme, the computer program instructions stored in the computer usable or computer readable memory may also produce manufacturing articles including instruction means performing the functions described in block(s) of the flow charts. Because the computer program instructions may also be mounted on the computer or the other programmable data processing apparatuses, the instructions performing a series of operation steps on the computer or the other programmable data processing apparatuses to create processes executed by the computer to thereby execute the computer or the other programmable data processing apparatuses may also provide steps for performing the functions described in block(s) of the flow charts.

In addition, each block may indicate a modules, a segment, and/or a code including one or more executable instructions for executing a specific logical function(s). Further, functions mentioned in the blocks occur regardless of a sequence in some alternative embodiments. For example, two blocks that are consecutively illustrated may be simultaneously performed in fact or be performed in a reverse sequence depending on corresponding functions sometimes.

Herein, the term "unit" may include software and/or hardware components, such as a field-programmable gate array (FPGA) and/or an application-specific integrated circuit (ASIC). However, the meaning of "unit" is not limited to software and/or hardware. For example, a unit may be configured to be in a storage medium that may be addressed and may also be configured to reproduce one or more processor. Accordingly, a "unit" may include components such as software components, object oriented software components, class components, task components, processors, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuit, data, database, data structures, tables, arrays, and variables.

Functions provided in the components and the "units" may be combined with a smaller number of components and/or "units" or may further separated into additional components and/or "units".

In addition, components and units may also be implemented to reproduce one or more CPUs within a device or a security multimedia card.

The terms as used in the present disclosure are provided to describe specific embodiments, and do not limit the scope of other embodiments. It is to be understood that singular forms include plural forms unless the context clearly dictates otherwise. Unless otherwise defined, the terms and words including technical or scientific terms used in the following description and embodiments may have the same meanings as generally understood by those skilled in the art. The terms as generally defined in dictionaries may be interpreted as having the same or similar meanings as the contextual meanings of related technology. Unless otherwise defined, the terms should not be interpreted as ideally or excessively formal meanings. When needed, even the terms as defined in the present disclosure may not be interpreted as excluding embodiments of the present disclosure.

Herein, a base station performs resource allocation to a terminal. Examples of the base station may include an eNode B, a Node B, a wireless access unit, a base station controller, a node on a network, etc. Examples of the terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, a multimedia system performing a communication function, etc..

Herein, a downlink (DL) is a radio transmission path of a signal from a base station to a UE and an uplink (UL) is a radio transmission path of a signal from the UE to the base station.

The embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel forms.

A system transmission bandwidth per carrier of LTE and LTE-A is limited to a maximum of <NUM>, while a <NUM> system is expected to provide super-high speed data services of several Gbps using an ultra-wide bandwidth, which is much wider than LTE and LTE-A. As a result, a candidate frequency for the <NUM> system is a very high frequency band from several GHz to <NUM>, which is a relatively easy to secure ultra-wideband frequency.

A method of securing a wideband frequency for the <NUM> system is also considered by frequency reallocation or allocation in a frequency band of several hundreds of MHz to several GHz to several GHz, as used in a current mobile communication system.

A radio wave in a very high frequency band has a wavelength of several mm, and therefore, may be referred to as a millimeter wave (mmWave). However, in a very high frequency band, a pathloss of the radio wave increases in proportion to the frequency band, such that the coverage of the mobile communication system decreases.

To overcome the disadvantage of the reduction in the coverage of the very high frequency band, a beamforming technique for concentrating radiation energy of a radio wave onto a predetermined destination by using a plurality of antennas to increase an arrival distance of the radio wave is becoming more important. The beamforming technique may be applied to a transmitting end and a receiving end.

In addition to increasing the coverage by using the beamforming technique, interference is reduced in a region other than the beamforming direction.

As another requirement of the <NUM> system, there is an ultra-low latency service having a transmission delay of about <NUM> between the transmitting and receiving ends. By one method for reducing a transmission delay, a frame structure design based on short transmission time interval (TTI) compared to LTE and LTE-A is possible. The TTI is a basic unit for performing scheduling, and the TTI of LTE and LTE-A systems is <NUM> corresponding to a length of one subframe. For example, the short TTI to meet the requirements for the ultra-low latency service of the <NUM> system may be <NUM>, <NUM>, <NUM>, etc., that are shorter than LTE and LTE-A systems.

In the following description, unless otherwise stated, a TTI or a subframe is a basic unit of scheduling and may be interchangeably used with each other.

<FIG> illustrates a basic structure of a time-frequency resource domain of LTE and LTE-A systems.

Referring to <FIG>, a horizontal axis represents a time domain and a vertical axis represents a frequency domain. A terminal transmits data or a control signal to a base station through a UL and a base station transmits data or a control signal to the terminal through a DL. A minimum transmission unit in the time domain of LTE and LTE-A systems is an orthogonal frequency division multiplexing (OFDM) symbol in the DL and a single-carrier frequency division multiple access (SC-FDMA) symbol in the UL, in which a slot <NUM> is formed by Nsymb symbols <NUM> and a subframe <NUM> is formed by two slots. A radio frame <NUM> is a time domain unit including <NUM> subframes. A minimum transmission unit in the frequency domain is a subcarrier in a unit of <NUM> (subcarrier spacing is <NUM>), and the overall system transmission bandwidth consists of a total of NBW subcarriers <NUM>.

A basic unit of the resource in the time-frequency domain is a resource element (RE) <NUM>, which may be represented by an OFDM symbol index or an SC-FDMA symbol index and a subcarrier index. A resource block (RB) <NUM> (or a physical resource block (PRB)) is defined by the Nsymb consecutive OFDM symbols <NUM> in the time domain and NRB consecutive subcarriers <NUM> in the frequency domain. Therefore, the RB <NUM> includes Nsymb x NRB REs <NUM>.

In LTE and LTE-A systems, data is mapped in an RB unit, and a base station performs scheduling in an RB-pair unit configuring one subframe for a predetermined terminal. The number of SC-FDMA symbols or the number Nsymb of OFDM symbols is determined depending on a cyclic prefix (CP) length added to each symbol to prevent inter-symbol interference. For example, if a normal CP is applied, Nsymb = <NUM>, and if an extended CP is applied, Nsymb = <NUM>. The extended CP is applied to a system having a radio wave transmission distance that is relatively longer than the normal CP, thereby maintaining inter-symbol orthogonally. In addition, the CP length per symbol is additionally adjusted in order to configure one subframe with an integer number of symbols. For example, for the normal CP, a CP length of a first symbol of each slot is <NUM>µsec and a CP length of the remaining symbols of each slot is <NUM>µsec. Since the OFDM symbol length is inversely related to the subcarrier spacing, each OFDM symbol length is <NUM>/<NUM> = <NUM>µsec. If the CP length is included, the length of the first symbol of each slot is <NUM>µsec and the length of the remaining symbols of each slot is <NUM>µsec. A length Tl of an l-th symbol may be expressed using Equation <NUM>. <MAT> <MAT> <MAT>.

The subcarrier spacing, the CP length, etc., are information for OFDM transmission and reception and should be recognized as a common value by the base station and the terminal to smoothly transmit and receive a signal.

Further, NBW and NRB are proportional to the system transmission bandwidth. Accordingly, a data rate is increased in proportion to the number of RBs scheduled in the terminal.

As described above, an operating frequency band of the <NUM> system ranges from hundreds of MHz to <NUM>. Therefore, it is difficult to transmit and receive signals suitable for the channel environment for each frequency band by operating a single frame structure over the entire frequency band. That is, there is a need for efficient signal transmission and reception by operating a frame structure in which subcarrier spacing is defined in accordance with the subdivision of the operating frequency band. For example, in a high frequency band, it is desirable to keep the subcarrier spacing relatively large in order to overcome performance deterioration due to phase noise. In addition to the operating frequency band, a cell size may also be a primary consideration defining the frame structure. For example, when the cell size is large, it is preferable to apply a relatively long CP length in order to avoid the inter-symbol interference due to a multi-path propagation signal. Herein, for convenience of explanation, the frame structure defined according to various scenarios, such as the operating frequency band and the cell size, will be referred to as a scalable frame structure.

An aspect of the present disclosure is to define parameter sets for a scalable frame structure for each operating scenario and to maintain compatibility between the parameter sets for efficient system operation. The parameter set includes subcarrier spacing, a CP length, etc., and the operating scenario may be defined according to service types such as an operating frequency band, a cell size, enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), and a massive MTC.

<FIG>, <FIG>, and <FIG> illustrate a scalable frame structure according to an embodiment of the present disclosure.

In <FIG>, the parameter sets defining the scalable frame structure include a subcarrier spacing, a CP length, a length of the subframe, etc..

It is expected that LTE/LTE-A systems and the <NUM> systems will initially coexist or operate in a dual mode. Therefore, a scalable frame structure of the <NUM> system should include at least the frame structure of LTE and LTE-A or the parameter sets.

<FIG> illustrates a <NUM> frame structure or parameter sets, such as the frame structure of LTE and LTE-A. Referring to <FIG>, in a frame structure type A, a subcarrier spacing is <NUM>, <NUM> symbols configure a <NUM> subframe, and <NUM> subcarriers (= <NUM> = <NUM> x <NUM>) configure a PRB.

Referring to <FIG>, in a frame structure type B, a subcarrier spacing is <NUM>, <NUM> symbols configure a <NUM> subframe, and <NUM> subcarriers (= <NUM> = <NUM> x <NUM>) configure a PRB. Therefore, the subcarrier spacing and the PRB size are twice as larger as those of the frame structure type A, and the length of the subframe and the length of the symbol are twice as short as those of the frame structure type A.

Referring to <FIG>, in a frame structure type C, a subcarrier spacing is <NUM>, <NUM> symbols configure a <NUM> subframe, and <NUM> subcarriers (= <NUM> = <NUM> x <NUM>) configure a PRB. Therefore, the subcarrier spacing and the PRB size are four times as large as those of the frame structure type A, and the length of the subframe and the length of the symbol are four times as long as those of the frame structure type A.

If the frame structure type is generalized, the subcarrier spacing, the CP length, and the length of the subframe, which make up the parameter sets, have an integer multiple relationship with each other for each type, such that high scalability may be provided. In addition, as with characteristics of LTE frame structure, the CP length of some symbols in the subframe may differ from the CP length of the remaining symbols in the subframe under the determined frame structure.

The above-mentioned frame structure type may be applied corresponding to various scenarios. From the viewpoint of cell size, it is possible to support a cell having a larger size as the CP length is increased, such that the frame structure type A may support cells relatively larger than the frame structure types B and C. From the viewpoint of operating frequency band, as subcarrier spacing increases, it is more advantageous in restoring the phase noise in the high frequency band, such that the frame structure type C may support a relatively higher operating frequency than the frame structure types A and B. From the viewpoint of services, to support an ultra-low delay service like URLLC, it is advantageous to make the length of the subframe shorter, and therefore, the frame structure type C is relatively more suitable for the URLLC service over the frame structure types A and B.

In addition, a scenario for multiplexing the frame structure types in one system and integrally operating them may be considered.

<FIG> illustrates frame structure types A, B, and C multiplexed in one system according to an embodiment of the present disclosure.

Referring to <FIG>, type A <NUM>, type B <NUM>, and type C <NUM> are multiplexed in one system. That is, by maintaining an integer multiple relationship between the essential parameter sets defining the frame structure type, resource mapping in a subframe or in the PRB is smoothly performed, even when multiplexing as illustrated in <FIG>.

For an initial access of a terminal, a physical broadcast channel (PBCH) for providing control information for the initial access, such as time-frequency synchronization with the system, a synchronization signal for providing a cell ID, and system bandwidth information, a physical random access channel (PRACH) for random access of a terminal may be used. However, in a <NUM> system supporting various frame structure types as described above, the frame structure type to be applied to an initial access channel, such as the synchronization signal, the PBCH, and the PRACH, should be defined.

In the present disclosure, in a <NUM> system supporting various frame structure types as described above, two methods are defined for an initial access operation of a terminal. In a first method, the initial access channel may be defined for each frame structure type. In a second method, a common initial access channel may be defined.

<FIG> is a flow chart illustrating operations of the base station and the terminal according to the first method.

Referring to <FIG>, in step <NUM>, the base station sets channels for initial access for each parameter set or each frame structure type and transmits them to the each terminal. For example, in a system supporting all the frame structure types A, B, and C, the base station maps the channels for initial access, each applied with the frame structure types A, B, and C, to a separate time-frequency resource and transmits them.

In step <NUM>, the terminal detects the initial access channel depending on the parameter set or the frame structure type supported by the terminal. If the terminal fails to detect the initial access channel in step <NUM>, the terminal repeatedly performs the operation of step <NUM>.

In step <NUM>, the terminal performs a random access using a random access channel corresponding to the parameter set or the frame structure type successfully detected by the terminal in step <NUM>.

<FIG> is a flowchart illustrating operations of the base station and the terminal according to the second method.

Referring to <FIG>, in step <NUM>, the base station sets the initial access channel independent of the parameter set or the frame structure type, and transmits it to the terminal.

In step <NUM>, the terminal detects a common initial access channel. If the terminal fails to detect the common initial access channel in step <NUM>, the terminal repeatedly performs step <NUM>.

In step <NUM>, the terminal performs the random access using the common initial access channel.

The base station receives the random access attempt over the common initial access channel of the terminal, and sets a parameter set or a frame structure type to be applied to signal transmission/reception between the terminal and the base station in step <NUM>.

<FIG> illustrates a coexistence relationship between a frame structure type A and LTE in the time domain according to an embodiment of the present disclosure.

Referring to <FIG>, because the frame structure type A is the same as that of LTE frame structure, the <NUM> system is synchronized with LTE system in a subframe unit and in a symbol unit in subframes. In particular, for LTE, a CP length <NUM> of a first symbol #<NUM> of each slot is longer than the CP length of the remaining symbols #<NUM> to #<NUM> in the slot and the frame structure type A is likewise applied with the above structure <NUM>, such that the inter-symbol synchronization between LTE system and the <NUM> system is achieved.

Therefore, if a cell A is applied with LTE system and a cell B, which is a neighbor to the cell A, is applied with the <NUM> system to which the frame structure type A is applied, as illustrated in <FIG>, the symbol of LTE is time synchronized with the symbol of the <NUM>, such that it is possible to minimize inter-cell interference caused by a mismatch of the time synchronization. A length TtypeA,l of a symbol of the l-th symbol of each slot in the subframe of the frame structure type A subframe may be expressed by Equation <NUM>, which is similar to Equation <NUM>. <MAT> <MAT> <MAT>.

Table <NUM> below shows a CP length of an l-th symbol of each slot in a subframe of the frame structure type A, a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of µsec.

Table <NUM> below shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type A, a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of Ts that represents the time domain (where various Ts values are assumed). Ts is in the relationship of Ts = <NUM> / (subcarrier spacing x fast Fourier transform (FFT) size), depending on the subcarrier spacing and the maximum FFT size assumed in the system. For an LTE system, Ts = <NUM> / (<NUM> x <NUM>) sec is applied.

<FIG> illustrates a coexistence relationship between a frame structure type B and LTE in the time domain according to an embodiment of the present disclosure.

Referring to <FIG>, in the frame structure type B, because the length of the symbol and the length of the subframe are reduced by two as compared to LTE, a <NUM> subframe of LTE corresponds to two <NUM> subframes of the <NUM>. Therefore, a <NUM> subframes of the <NUM> may be time synchronized with a <NUM> slot of LTE, or two <NUM> subframes of the <NUM> may be synchronized with a <NUM> subframe of LTE. However, two symbols of the <NUM> system are not necessarily synchronized with one symbol of an LTE system. For example, a length Y <NUM> of symbol #<NUM> of an LTE system is equal to a sum Y'<NUM> of the lengths of symbols #<NUM> and #<NUM> of the <NUM> system, but a length X <NUM> of symbol #<NUM> of the LTE system is longer than a sum X' <NUM> of symbols #<NUM> and #<NUM> of the <NUM> system because the length of the first symbol of each slot in the LTE subframe is longer than the length of remaining symbols.

A length TtypeB,I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type B may be expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

Referring to Equation (<NUM>) and <FIG>, the lengths of the X <NUM> and the X'<NUM> do not match each other, even if the subframe of the LTE system is time synchronized with the subframe of the <NUM> system. As a result, two symbols of the <NUM> system are time synchronized with one symbol of LTE only after a start point <NUM> of the first slot of the LTE symbol (<NUM>, <NUM>, and <NUM>). Therefore, a mutual interference problem may still occur between LTE and a <NUM> system due to the time synchronization mismatch, before reference numeral <NUM>.

For example, in the LTE system, the subframe performs DL transmission for the symbols #<NUM>, #<NUM>, and #<NUM>. If the URLLC data burst is transmitted as the UL in one symbol in the symbol #<NUM> of the <NUM> system, the UL transmission in the symbol #<NUM> of the <NUM> system acts as the interference over the symbols #<NUM> and #<NUM> of the LTE system due to the mismatch of the time synchronization. However, if the time synchronization is made, the UL transmission in the symbol #<NUM> of the <NUM> system is limited only to the symbol #<NUM> of the LTE system, and thus, acts as interference.

The above problem may likewise occur when the <NUM> system using the frame structure type A and the <NUM> system using the frame structure type B coexist.

Accordingly, to reduce the interference problem between the LTE system and the <NUM> system, a frame structure type B' is defined, wherein a length TtypeB',I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type B' may expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

<FIG> illustrates a frame structure type B' according to an embodiment of the present disclosure.

Referring to <FIG>, a CP length <NUM> of symbol #<NUM> of a first slot (even-numbered slot, slot #<NUM>) in a subframe in the frame structure type B' is equal to a sum of a CP length <NUM> of symbol #<NUM> of the frame structure type B and a difference <NUM> between CP lengths of the symbol #<NUM> and other symbols. Further, a CP length <NUM> of symbol #<NUM> of a second slot in the subframe is equal to the CP length of the remaining symbols #<NUM> to #<NUM>. Therefore, the two symbols of the frame structure type B' are time synchronized with one symbol of the LTE system. Referring to <FIG>, the CP length of the first symbol arriving every <NUM> is relatively longer than the CP length of the remaining symbols.

<FIG> illustrates a frame structure type B" according to an embodiment of the present disclosure.

Referring to <FIG>, CP lengths <NUM> and <NUM> of symbols #<NUM> and #<NUM> of a first slot (even-numbered slot, slot #<NUM>) in a subframe in the frame structure type B' are equal to CP lengths <NUM> and <NUM> of symbol #<NUM> of the frame structure type B. By arranging two symbols <NUM> and <NUM> having a relatively long CP length at the head of the subframe, the sum of the lengths of the two symbols <NUM> and <NUM> is equal to the symbol #<NUM> of the LTE subframe, and therefore, time synchronization is possible. Further, a CP length <NUM> of symbol #<NUM> of a second slot in the subframe is equal to the CP length of the remaining symbols #<NUM> to #<NUM>. Therefore, the two symbols of the frame structure type B" are time synchronized with one symbol of the LTE system.

Referring to <FIG>, the CP lengths of the first and second symbols arriving every <NUM> are relatively longer than the CP length of the remaining symbols.

A length Ttyp,B",I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type B" may be expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

Table <NUM> below shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type B' and the frame structure type B", a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of µsec.

Table <NUM> below shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type B', a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of Ts that represents the time domain (where various Ts values are assumed).

Table <NUM> below shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type B", a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of Ts that represents the time domain (where various Ts values are assumed).

<FIG> illustrates a coexistence relationship between a frame structure type C and LTE in the time domain according to an embodiment of the present disclosure. Specifically, <FIG> illustrates a coexistence relationship with LTE in the time domain when the frame structure type C is applied to a <NUM> system.

Referring to <FIG>, if the frame structure type C has a length of a symbol and a subframe reduced by four times compared to LTE, <NUM> subframe of LTE corresponds to four <NUM> subframes (subframe #<NUM>, #<NUM>, #<NUM>, and #<NUM>) of the <NUM> system. Therefore, four <NUM> subframes of the <NUM> are time synchronized with one <NUM> subframe of the LTE subframe. However, four symbols of the <NUM> system are not necessarily time synchronized with one symbol of the LTE system. For example, a length Y <NUM> of symbol #<NUM> of the LTE system is equal to a sum Y' <NUM> of lengths of symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a second slot of the <NUM> system, but a length X <NUM> of symbol #<NUM> of the LTE system is longer than a sum X' <NUM> of symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of the <NUM> system because the length of the first symbol of each slot in the LTE subframe is longer than the length of remaining symbols.

Referring to <FIG>, one symbol of LTE is time synchronized with four symbols of the <NUM> system at a start point <NUM> of symbol #<NUM> of a first slot of the LTE system. Therefore, the mutual interference problem may occur between LTE and a <NUM> system due to the time synchronization mismatch, before symbol #<NUM><NUM> of the first slot of the LTE system.

A length TtypeC,I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type C may be expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

<FIG> illustrates a frame structure type C' according to an embodiment of the present disclosure.

A length TtypeC,I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type C' may be expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

Referring to <FIG>, CP lengths <NUM> and <NUM> of symbol #<NUM> of a first slot (even-numbered slot, slot #<NUM>) of even-numbered subframes (subframes #<NUM> and #<NUM>) among four <NUM> subframes (subframes #<NUM>, #<NUM>, #<NUM>, and #<NUM>) of the <NUM> corresponding to <NUM> subframe of LTE in the frame structure type C' are equal to a sum of a CP length <NUM> of symbol #<NUM> of the frame structure type C and three times of a difference between CP lengths of symbol #<NUM> and other symbols (<NUM>, <NUM>, and <NUM>). Further, CP lengths <NUM> and <NUM> of symbol #<NUM> in a second slot in the even-numbered subframes (subframes #<NUM> and #<NUM>) and CP lengths <NUM> and <NUM> of symbol #<NUM> of the odd-numbered subframes (subframes #<NUM> and #<NUM>) are equal to the CP lengths of the remaining symbols #<NUM> to #<NUM>. Therefore, four symbols of the frame structure type C' are time synchronized with one symbol of LTE. In <FIG>, the CP length of the first symbol arriving every <NUM> is relatively longer than the CP length of the remaining symbols.

<FIG> illustrates a correspondence relationship between a frame structure type B' and a frame structure type C' according to an embodiment of the present disclosure.

Referring to <FIG>, symbol #<NUM><NUM> of the LTE system is time synchronized with symbols #<NUM> and #<NUM><NUM> of the frame structure type B' and frame structure types #<NUM> to #<NUM><NUM>. A symbol of the LTE system is time synchronized with each two symbols of the frame structure type B' and each four symbols of the frame structure type C'. Further, the frame structure type A and the frame structure types B' and C' have the same time synchronization relationship.

<FIG> illustrates a frame structure type C" according to an embodiment of the present disclosure.

Referring to <FIG>, CP lengths <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a first slot (even-numbered slot, slot #<NUM>) of even-numbered subframes (subframes #<NUM> and #<NUM>) among four <NUM> subframes (subframes #<NUM>, #<NUM>, #<NUM>, and #<NUM>) of the <NUM> system corresponding to <NUM> subframe of LTE in the frame structure type C" are equal to CP lengths <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of symbol #<NUM> of the frame structure type C. That is, four symbols <NUM>, <NUM>, <NUM>, and <NUM> having relatively long CP lengths of two subframes (subframe #<NUM> and #<NUM>) are disposed at the head of even-numbered subframes, and thus, the sum of the lengths of the four symbols <NUM>, <NUM>, <NUM>, and <NUM> are time synchronized with the symbol #<NUM> of the subframe of LTE.

Further, CP lengths <NUM> and <NUM> of symbol #<NUM> in a second slot in the even-numbered subframes (subframes #<NUM> and #<NUM>) and CP lengths <NUM>, <NUM>, <NUM>, and <NUM> of symbol #<NUM> of the odd-numbered subframes (subframes #<NUM> and #<NUM>) are equal to the CP lengths of the remaining symbols #<NUM> to #<NUM>. Therefore, the four symbols of the frame structure type C" are time synchronized with one symbol of the LTE system. In <FIG>, the CP length of the first four symbols arriving every <NUM> is relatively longer than the CP length of the remaining symbols.

A length TtypeC,I of a symbol of the l-th symbol of each slot in the subframe of the frame structure type C" may be expressed by Equation <NUM>. <MAT> <MAT> <MAT> <MAT>.

Table <NUM> shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type C' and the frame structure type C", a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of µsec.

Table <NUM> shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type C', a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of Ts that represents the time domain (where various Ts values are assumed).

Table <NUM> shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type C", a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of Ts that represents the time domain (where various Ts values are assumed).

A frame structure type D has a subcarrier spacing that is smaller than the subcarrier spacings of LTE and LTE-A, i.e., the subcarrier spacing is <NUM>, <NUM> symbols configure <NUM> subframes, and <NUM> subcarriers (= <NUM> = <NUM> x <NUM>) configure the PRB. The subcarrier spacing and the PRB size are twice as small as those of the frame structure type A, and the length of the subframe and the length of the symbol are twice as long as those of the frame structure type A. The lengths of the symbol of the LTE and LTE-A systems are uneven, and therefore, one symbol of the frame structure type D is not necessarily time-synchronized with two symbols of the LTE/LTE-A system.

<FIG> illustrates a frame structure type D and a frame structure type D' according to an embodiment of the present disclosure.

Referring to <FIG>, two symbols of LTE and LTE-A systems are time-synchronized with one symbol of the frame structure type D, after a start point <NUM> of symbol #<NUM> of a first slot of the frame structure type D (<NUM>, <NUM>, and <NUM>).

Referring to <FIG>, the CP length of the symbol #<NUM><NUM> of the frame structure type D' in which the symbol positions are overlapped with the symbol #<NUM><NUM> and <NUM> of LTE and LTE-A systems is equal to the sum of a CP length of symbol #<NUM><NUM> and a CP length of symbol #<NUM><NUM> of LTE and LTE-A systems. Similarly, a CP length of symbol #<NUM><NUM> of the frame structure type D' in which the symbol position are overlapped with the symbol #<NUM><NUM> of LTE and LTE-A systems is equal to the sum of a CP length of symbol #<NUM><NUM> and a CP length of symbol #<NUM><NUM> of LTE and LTE-A systems.

CP lengths of symbols #<NUM>, #<NUM>, #<NUM>, #<NUM> and #<NUM> of the other frame structure type D' are twice as long as the CP lengths of the remaining symbols other than the symbol #<NUM> of LTE and LTE-A systems. Therefore, two symbols of LTE and LTE-A systems are synchronized with one symbol of the frame structure type D'.

Table <NUM> below shows a CP length of the l-th symbol of each slot in the subframe of the frame structure type D', a length of the symbol from which the CP is excluded, and a length of the symbol including the CP in a unit of µsec.

<FIG> is a flow chart illustrating a transmission/reception operation by a terminal according to an embodiment of the present disclosure.

Referring to <FIG>, in step <NUM>, the terminal acquires system time synchronization from the base station. For example, the system time synchronization includes time synchronization, such as a radio frame and a subframe, and the synchronization is acquired through an initial access procedure of the terminal.

In step <NUM>, the terminal acquires the frame structure type information from the base station. The base station may notify the terminal of the frame structure type information by semi-static signaling or dynamic signaling, or the terminal may determine the frame structure type information by blind detection. The base station and the terminal know beforehand about the channel through which the signaling is transmitted depending on which frame structure type is used to reduce the terminal complexity.

In step <NUM>, the terminal acquires the frame structure type information and adjusts the subcarrier spacing, the CP length per symbol, the length of the subframe, etc., which make up the parameter sets, according to the corresponding frame structure type.

In step <NUM>, the terminal transmits and receives a signal to and from the base station depending on the adjusted parameter sets.

Another aspect of the present disclosure is to reduce mutual interference, without adjusting the length or the position of the CP for each frame structure type in a system applying two different types of frame structures.

<FIG> illustrates a method for reducing interference in a system to which different types of frame structures are applied according to an embodiment of the present disclosure.

Referring to <FIG>, item (a) shows a relationship between the frame structure type A and the frame structure type B. If the length of the symbol of the frame structure type B is <NUM>/<NUM> of the length of the symbol of the frame structure type A, the time synchronization in the symbol unit of the frame structure type A and the frame structure type B before a start point <NUM> of symbol #<NUM> of the symbol structure type A is not made. That is, the time synchronization with the symbol of the frame structure type B is made only at start points of the symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of each slot based on the frame structure type A because the CP length of the symbol #<NUM> is relatively long, and the signal transmission in an interval in which the time synchronization between the symbols is not made causes the interference with the signal using the counterpart frame structure type.

More specifically, the signal transmission in the symbols #<NUM>, #<NUM> and #<NUM> of the frame structure type B causes signal interference on two symbols (symbol #<NUM> and symbol #<NUM>, symbol #<NUM> and symbol #<NUM>, symbol #<NUM> Symbol #<NUM>) in the frame structure type A, which may lead to a deterioration in system performance. Therefore, in this case, there is a need to put restraints to avoid the symbols that overlap the symbol boundaries of the symbols #<NUM>, #<NUM>, and #<NUM> in the frame structure type A as a starting point at which a signal may be transmitted in the frame structure type B. That is, from the viewpoint of the frame structure type B, the starting point of the signal transmission becomes symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of the first slot and symbols #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> of the second slot.

Item (b) shows the relationship between the frame structure type A and the frame structure type C. If the length of the symbol of the frame structure type C is <NUM>/<NUM> times of the length of the symbol of the frame structure type A, before a start point <NUM> of symbol #<NUM> of the symbol structure type A, the time synchronization in the symbol unit of the frame structure type A and the frame structure type C is not made. That is, the time synchronization with the symbol of the frame structure type C is made only at start points of the symbols #<NUM> and #<NUM> of each slot based on the frame structure type A. Therefore, in this case, there is a need to put restraints to avoid the symbols that overlap the symbol boundaries of the symbols #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> in the frame structure type A as a starting point at which a signal may be transmitted in the frame structure type C. That is, from the viewpoint of the frame structure type C, the start points of the signal transmission become symbols #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a first slot of subframe #<NUM>, symbols #<NUM>, #<NUM>, #<NUM>, #<NUM> and #<NUM> of a second slot of subframe #<NUM>, symbols #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a first slot of subframe #<NUM>, and #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a second slot of subframe #<NUM>.

Item (c) shows a relationship between the frame structure type B and the frame structure type C. If the length of the symbol of the frame structure type C is <NUM>/<NUM> times of the length of the symbol of the frame structure type B, before a start point <NUM> of symbol #<NUM> of the symbol structure type B, the time synchronization in the symbol unit of the frame structure type B and the frame structure type C is not made. That is, the time synchronization with the symbol of the frame structure type C is made only at start points of symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of each slot based on the frame structure type B. Therefore, in this case, there is a need to put restraints to avoid the symbols that overlap the symbol boundaries of the symbols #<NUM>, #<NUM>, and #<NUM> in the frame structure type B as a starting point at which a signal may be transmitted in the frame structure type C. That is, from the viewpoint of the frame structure type C, the starting point of the signal transmission becomes symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of the first slot and symbols #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> of the second slot.

Accordingly, a start symbol position capable of the signal transmission in the frame structure type having a shorter symbol length between frame structure types having N times scalability of a symbol length of each frame structure type can be generalized as follows:.

<FIG> illustrates a terminal apparatus according to an embodiment of the present disclosure.

Referring to <FIG>, the terminal includes a transmitter <NUM> including a UL transmission processor <NUM>, a multiplexer <NUM>, a radio frequency (RF) transmitter <NUM>, a receiver <NUM> including a DL reception processor <NUM>, a demultiplexer <NUM>, and an RF receiver <NUM>, and a controller <NUM>. Alternatively, the transmitter <NUM> and the receiver <NUM> may be implemented in a single unit as a transceiver, and each component may be implemented through one or more processors.

The controller <NUM> determines which scalable frame structure is applied based on a signal detected from the base station or signaling of the base station to control the receiver <NUM> for the DL signal reception of the terminal and the transmitter <NUM> for the UL signal transmission. Specifically, the controller <NUM> may confirm the scalable frame structure applied at the time of the signal transmission to transmit and receive the signal to and from the base station depending on the scalable frame structure.

The UL transmission processor <NUM> may perform processes, such as the channel coding and modulation, to generate a signal to be transmitted. The signal generated from the UL transmission processor <NUM> is multiplexed with other uplink signals by the multiplexer <NUM>, processed by the RF transmitter <NUM>, and then transmitted to the base station.

In the receiver <NUM>, the RF receiver <NUM> receives a signal from the base station, the demultiplexer <NUM> demultiplexes the received signal, and distributes the demultiplexed signal to the DL reception processor <NUM>. The DL reception processor <NUM> performs processes, such as demodulation and channel decoding, on the downlink signal of the base station to obtain control information or data transmitted by the base station. The receiver <NUM> applies the output result of the DL reception processor <NUM> to the controller <NUM> to support the operation of the controller <NUM>.

<FIG> illustrates a base station apparatus according to an embodiment to the present disclosure.

Referring to <FIG>, the base station includes a transmitter <NUM> including a DL transmission processor <NUM>, a multiplexer <NUM>, and an RF transmitter <NUM>, a receiver <NUM> including a UL reception processor <NUM>, a demultiplexer <NUM>, and an RF receiver <NUM>, and a controller <NUM>. Alternatively, the transmitter <NUM> and the receiver <NUM> may be implemented in a single unit as a transceiver, and each component may be implemented through one or more processors.

The controller <NUM> determines which scalable frame structure is applied in order to control the receiver <NUM> for the UL signal reception and the transmitter <NUM> for the DL signal transmission. Further, the controller <NUM> controls the transmitter <NUM> to transmit information on the scalable frame structure to the terminal. Specifically, the controller <NUM> may confirm the scalable frame structure applied at the time of the signal transmission in order to transmit and receive the signal to and from the terminal depending on the scalable frame structure.

The downlink transmission processor <NUM> performs the processes, such as channel coding and modulation, to generate a signal to be transmitted. The signal generated from the DL transmission processor <NUM> is multiplexed with other downlink signals by the multiplexer <NUM>, processed by the RF transmitter <NUM>, and then transmitted to the terminal.

In the receiver <NUM>, the RF receiver <NUM> receives a signal from the terminal, the demultiplexer <NUM> demultiplexes the received signal, and distributes the demultiplexed signal to the UL reception processor <NUM>. The UL reception processor <NUM> performs processes, such as demodulation and channel decoding, on the UL signal of the terminal to obtain control information or data transmitted by the terminal. The receiver <NUM> applies the output result of the UL reception processor <NUM> to the controller <NUM> to support the operation of the controller <NUM>.

Alternatively, the base station may also include the transceiver and the controller capable of controlling the same. Further, the transceiver and the controller may include at least one processor.

The above-described embodiments of the present disclosure and the accompanying drawings have been provided only as specific examples in order to assist in understanding the present disclosure and do not limit the scope of the present disclosure. Accordingly, those skilled in the art to which the present disclosure pertains will understand that other change examples based on the technical idea of the present disclosure may be made without departing from the scope of the present disclosure.

Claim 1:
A method performed by a base station in a wireless communication system, the method comprising:
transmitting, to a terminal, information indicating a subcarrier spacing corresponding to a frame structure among a plurality of frame structures; and
transmitting, to the terminal, scheduling information based on a transmission time interval, TTI, of the frame structure, as a unit of a scheduling,
wherein the plurality of frame structures include a first frame structure (<NUM>) and a second frame structure (<NUM>),
wherein a subcarrier spacing of the second frame structure (<NUM>) is twice as wide as a subcarrier spacing of the first frame structure (<NUM>), and wherein the subcarrier spacing of the first frame structure (<NUM>) is <NUM> and the subcarrier spacing of the second frame structure (<NUM>) is <NUM>, and
wherein a first TTI of the first frame structure (<NUM>) and a second TTI of the second frame structure (<NUM>) each include <NUM> symbols, and duration of the first TTI is <NUM> and duration of the second TTI is <NUM>,
wherein each of symbol duration of a first symbol and symbol duration of an eighth symbol in the first TTI is longer than symbol duration of any of other symbols in the first TTI, and symbol duration of a first symbol in the second TTI is longer than symbol duration of any of other symbols in the second TTI, and
wherein the symbol duration of the first symbol in the first TTI equals a sum of the symbol duration of the first symbol and symbol duration of a second symbol in the second TTI such that two symbols in the second TTI are time synchronized with one symbol of the first TTI.