KR101481038B1 - Apparatus and method for transmitting/receiving and efficient frame structure supporting variable cyclic prefix size in wireless communication system - Google Patents

Abstract

The present invention relates to an efficient frame structure for receiving a cyclic prefix (CP) having various lengths in a wireless communication system, and a transmitting and receiving apparatus and method, and more particularly, There is an advantage that communication reliability and performance can be improved when designing a communication system supporting various channel environments including a guard time for frame switching.

Frame structure, cyclic prefix (CP), fragmentary OFDM symbol, resource block design

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an efficient frame structure and a transmitting and receiving apparatus and a method for receiving cyclic prefixes of various lengths in a wireless communication system, and an apparatus and a method for transmitting and receiving the cyclic prefix,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to an efficient frame structure and a transmitting and receiving apparatus and method for receiving a cyclic prefix (CP) having various lengths in a wireless communication system.

The outdoor mobile communication environment and the indoor LAN communication environment are very different from each other in the conventional case. That is, in the conventional case, in the outdoor mobile communication environment, mobile communication such as GSM (Global System for Mobile communications), IS (Interim Standard) -95, WCDMA (Code Division Multiple Access) System has been developed and developed, and WiFi wireless LAN systems such as IEEE 802.11b and 802.11a have been developed and developed in the indoor LAN environment. These two systems have been developed and used in accordance with each other's communication environment and purpose. That is, the mobile communication system is mainly used for voice communication in a mobile environment, and the WiFi wireless LAN system has been mainly used for data communication for a note PC in an indoor environment. In the future, as user demands become more diverse and complex, future communication should provide various kinds of communication services such as voice and data at a time, and efficiently provide communication services both indoors and outdoors.

However, when using both the conventional outdoor mobile communication system and the indoor WiFi wireless LAN system, various problems arise. First, because the two systems are completely separate systems, interworking between the two systems is complex and slow. To solve this problem, a vertical handover technique such as a media independent handover (MIH) technique has been developed, but it requires a lot of complicated protocols and procedures and a long delay time. Second, the two systems are completely separate and separate systems, so they must use completely different frequencies. Currently, mobile communication systems use a licensed frequency and WiFi wireless LAN systems use an unlicensed frequency. In this case, there is a problem that it is difficult to use the frequency more flexibly, for example, by using an allowable frequency in order to improve communication reliability of the indoor system. Finally, the terminal has to implement both completely different systems, which increases the complexity.

One method for solving the above problem is to build a small outdoor mobile communication base station and install it in a room (hereinafter referred to as 'femtocell') and use it. The above method has no problem caused by interworking between the above-mentioned heterogeneous systems, and has the advantage that a carrier can use the frequency more autonomously. In addition, in the case of the femtocell, since the size of a cyclic prefix (hereinafter referred to as 'CP') required for a macro cell is short, the signal overhead Can be used to send a lot of data. However, a frame structure and an operation method capable of effectively encompassing systems having various CPs and increasing the spectral efficiency have not been conventionally described.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an efficient frame structure and a transmitting and receiving apparatus and method for accommodating CPs of various lengths in a wireless communication system.

It is another object of the present invention to variously change the size of the CP according to the channel environment in order to improve communication reliability and performance when designing a communication system supporting various channel environments in a wireless communication system, A method and apparatus for transmitting / receiving OFDM symbols using a fractional OFDM (Orthogonal Frequency Division Multiplexing) symbol in order to increase the spectral efficiency while changing the number of OFDM symbols in a frame or one subframe, and an efficient frame structure .

It is another object of the present invention to provide a frame structure compatible with a frame standard of an existing system so as to ensure maximum commonality with an existing system in a wireless communication system.

Another object of the present invention is to provide a frame structure that maximizes commonality so that the change is minimized when the TDD is designed in the wireless communication system and converted into FDD.

It is another object of the present invention to provide a frame structure supporting various types of CP sizes in a wireless communication system, and maintaining commonality in the whole frame.

It is another object of the present invention to provide an apparatus and method capable of flexibly ensuring a guard time in a communication system requiring a guard time by using a short OFDM symbol as a null symbol in a wireless communication system.

According to an aspect of the present invention, there is provided a frame structure for receiving a cyclic prefix (CP) of various lengths in a wireless communication system, the frame structure including at least one sub- Frame, and a guard time for frame switching.

According to an aspect of the present invention, there is provided a transmission apparatus for receiving a cyclic prefix (CP) having various lengths in a wireless communication system, the apparatus comprising: And an OFDM modulator for performing an Inverse Fast Fourier Transform (IFFT) operation on data in a frequency domain from the code and the modulator and outputting an OFDM symbol of a variable size, .

According to an aspect of the present invention, there is provided a transmission method of receiving a cyclic prefix (CP) having various lengths in a wireless communication system, the method comprising: receiving information data from an upper layer according to a predetermined modulation level; And generating an OFDM (Orthogonal Frequency Division Multiplexing) symbol of variable size by IFFT (Inverse Fast Fourier Transform) operation of the data of the code and the modulated frequency domain.

According to an aspect of the present invention, there is provided a receiving apparatus for receiving a cyclic prefix (CP) having various lengths in a wireless communication system, the receiving apparatus including: a receiving unit configured to receive a variable-size OFDM (Orthogonal Frequency Division Multiplexing) symbol An OFDM demodulator for performing Fast Fourier Transform (FFT) on the frequency domain data to output data in a frequency domain; and a transmitter for selecting data of subcarriers to be actually received from data in the frequency domain from the OFDM demodulator, And a demodulator and a decoder for demodulating and decoding the signal.

According to an aspect of the present invention, there is provided a receiving method of receiving a cyclic prefix (CP) of various lengths in a wireless communication system, the method comprising: receiving a variable-size OFDM symbol by a Fast Fourier Transform Selecting a data of subcarriers to be actually received from the data in the frequency domain and demodulating and decoding the selected data according to a predetermined demodulation level; .

In the wireless communication system, the size of the CP is changed in various ways according to the channel environment, thereby changing the number of OFDM symbols within one frame or one semi- frame or one subframe of fixed length, The present invention provides an apparatus and method for transmitting / receiving using fractional orthogonal frequency division multiplexing (OFDM) symbols in order to increase communication reliability and performance when designing a communication system supporting various channel environments by providing an efficient frame structure There is an advantage. In other words, reliable communication in a super macro area requiring a long CP, and in a region where a short CP such as a femtocell can be transmitted, There is an advantage.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

 Hereinafter, an efficient frame structure and a transmitting and receiving apparatus and method for accommodating CPs of various lengths in a wireless communication system according to the present invention will be described.

In order to improve communication reliability and performance when designing a communication system supporting various channel environments such as macro-cell / micro-cell communication and femto-cell communication, (Eg, CP = 1/4, 1/8, 1/16, 1/32, etc.) in accordance with the channel environment so that the size of the CP can be changed within one frame or one semi- frame or one sub- In order to increase the efficiency of the OFDM system, an apparatus and method for transmitting and receiving data using a fractional orthogonal frequency division multiplexing (OFDM) symbol (eg, 1.0, 0.5, 0.25, etc.) and an efficient frame structure are proposed.

Here, the requirements to be a frame structure of IEEE 802.16m are summarized as follows.

(1) Basic number design to ensure maximum commonality with IEEE 802.16e

- Yes, 20 msec superframe, 4 frames / superframe, 8 subframes / frame, other OFDM symbols / subframe

(2) a commonality between a time division duplex (TDD) and a frequency division duplex (FDD)

- Designed based on TDD, but designed to maximize commonality so that changes are minimized when converted to FDD.

(3) Support various CP sizes but maintain commonality in the whole frame

- 1/32 CP size (size): femtocell

- 1/16 CP size: Competing with LTE (Long Term Evolution) and UMB (Ultra Mobile Broadband)

- 1/8 CP size: Supports legacy systems (eg IEEE 802.16e systems), coexistence with IEEE 802.16e systems

- 1/4 CP size: FDD Rural cell, Super macro for NGMN (Next Generation Mobile Networks)

(4) Minimize unused idle period (minimize signal overhead)

1 is a block diagram showing the configuration of a transmitting and receiving apparatus in a wireless communication system according to the present invention.

As shown, the transmitting apparatus includes a code and modulator 100, an OFDM modulator 110, a digital to analog converter (DAC) 120, and a radio frequency (RF) processor 130, An RF processor 140, an analog-to-digital converter (ADC) 150, an OFDM demodulator 160, and a demodulator and decoder 170. Here, the transmitting apparatus is a base station, and the receiving apparatus is a terminal.

1, the code and modulator 100 codes and modulates information data from an upper layer according to a predetermined modulation level (e.g., a Modulation and Coding Scheme (MCS) level) And outputs it.

The OFDM modulator 110 performs Inverse Fast Fourier Transform (IFFT) on the frequency domain data from the code and modulator 100 and outputs time sample data (OFDM symbol). In particular, according to the present invention, the OFDM modulator 110 uses a N / M size IFFT operator to generate a short OFDM symbol, i.e., an OFDM symbol set A [n] ... (N / M) -1). Here, N is an IFFT size for generating a reference OFDM symbol, and M = 1, 2, 4 ... (i.e., M = 2 ^k , where k = 0, 1, 2, 3, Is a parameter for making a symbol size such as N / 2, N / 4 or the like. Alternatively, the N / M sized OFDM symbol may be generated using an N-sized IFFT operator. For this, the OFDM modulator 110 generates N sequences by appropriately inserting zeros into the N / M sequences, performs IFFT operations using an N-sized IFFT operator, Only sequences can be output.

The DAC 120 converts the time sample data from the OFDM modulator 110 into an analog signal and outputs the analog signal.

The RF processor 130 converts an analog signal from the DAC 120 into an RF signal and transmits the RF signal through an antenna.

Next, the RF processor 140 converts the RF signal received through the antenna into a baseband analog signal and outputs the baseband analog signal.

The ADC 150 converts the analog signal from the RF processor 140 into time sample data and outputs the time sample data.

The OFDM demodulator 160 performs Fast Fourier Transform (FFT) on the time sample data from the ADC 150 to output frequency-domain data. In particular, according to the present invention, the OFDM demodulator 160 may recover the received N / M sequences using an N / M size FFT operator, or generate N sequences by repeating the received N / M sequences M times And then restored using an N-size FFT operator.

The demodulator and decoder 170 selects data of subcarriers to be received from the frequency domain data from the OFDM demodulator 160 and demodulates the selected data according to a predetermined demodulation level (e.g., MCS level) Decoded and output.

2 is a diagram illustrating a superframe structure composed of regular subframes including a fragmentary OFDM symbol in a wireless communication system according to an embodiment of the present invention. Here, the superframe is designed by applying the same basic numbers as possible for commonality with the existing design.

Referring to FIG. 2, a 20-msec super frame 201 is composed of four frames 202, and one frame 202 is composed of eight sub-frames 203 and a guard time. At this time, the number of OFDM symbols 204 in one subframe 203 may be variously changed according to the channel environment. That is, one subframe 203 can accommodate 5.5 OFDM symbols, 6 OFDM symbols, 6.25 OFDM symbols, and 6.5 OFDM symbols according to the size of the CP. For example, when the subframe length is fixed to 617.14 μs, when only a small CP size (1/32) is required as in the case of a femtocell, 6.5 OFDM symbols are accommodated in one subframe, (6 OFDM symbols) of the OFDM symbol. Conversely, when a large CP size (1/4) as in a macro cell is required, 5.5 symbols can be accommodated in one sub-frame.

3 is a diagram illustrating a superframe structure composed of irregular subframes including a short OFDM symbol in a wireless communication system according to an embodiment of the present invention. Here, the superframe is designed by applying the same basic numbers as possible for commonality with the existing design.

3, the irregular subframe is different from the regular subframe of FIG. 2 in that all or some of the symbols or symbols in the last part of one subframe 311, 321, 331, and 341 are configured as null symbols so that data can not be transmitted by corresponding symbols. Such a subframe will be referred to as an irregular subframe. In the case of the TDD system, a guard time must be ensured for switching from UL to DL to an uplink (UL) from a downlink (DL). This guard time acts as a time overhead, and its size varies depending on the radius of the cell where the base station is installed. Therefore, in order to flexibly secure the necessary guard time in the TDD system and minimize the overhead, a guard time as close as possible to the necessary guard time is secured by using the last partial symbol of the subframe in a fragmentary manner. In other words, in the TDD system, when switching from DL to UL and UL to DL is required, the guard time is flexibly secured using irregular subframes only in the corresponding portion, and a short OFDM symbol is used to secure the necessary guard time The symbol is empty only by a symbol size closest to the maximum symbol size, that is, a null symbol is formed so that the overhead due to the guard time is reduced as much as possible.

4 is a diagram illustrating a superframe structure for providing TDD while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention. FIG. 4 illustrates a design of TDD as an essential requirement in designing an IEEE 802.16m frame structure, which maximizes commonality so as to minimize a change in conversion to FDD.

Referring to FIG. 4, in a superframe structure that provides TDD while accommodating a short OFDM symbol, one frame includes a regular subframe 401, a non-regular subframe 402, and a guard time 403 do. That is, the regular subframe 401 is used in most of the DL and UL sections constituting one frame, and the irregular subframe 402 is used only in the portion required to switch from DL to UL to UL to DL Flexibly secures the guard time required to switch from DL to UL and from UL to DL. The frame provides the same subframe size, and even if there is more than one switching point for DL / UL switching, the frame is changed in units of subframes, so that the interference caused by the non-synchronization of the subframes does not occur.

5 is a diagram illustrating a superframe structure for providing FDD while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention. FIG. 5 illustrates a design of TDD as an important requirement in designing an IEEE 802.16m frame structure, which maximizes commonality so that the change is minimized when converted to FDD.

Referring to FIG. 5, in a superframe structure that provides FDD while accommodating a fragment OFDM symbol, one frame includes a regular subframe 501 and a guard time 502. In the case of the frame providing the FDD, since DL and UL are provided through different bands, unlike frames providing TDD, it is not necessary to switch from DL to UL and from UL to DL, You do not need to use it.

6 is a diagram illustrating a superframe structure for providing IEEE 802.16e / 16m coexistence while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 6, a 20ms superframe that accommodates a short OFDM symbol and provides IEEE 802.16e / 16m coexistence is composed of four 5ms frames. The first subframe (first subframe) of each frame is used for the 16m superframe header in the first frame of the four frames and for the 16m DL zone in the remaining frames. The remaining subframes of each frame include the second and third subframes for the 16e DL zone, the fourth subframe for the 16m DL zone, the sixth subframe for the 16e UL zone, the 16m UL zone, 7 < th > and 8 < th > Alternatively, the remaining subframes of each frame may include a second subframe for the 16e DL zone, a third subframe for the 16m DL zone, a fifth subframe for the 16m UL zone, A sixth sub-frame for the UL zone, a seventh sub-frame for the 16m DL zone, and an eighth sub-frame for the 16m UL zone.

In both cases (a) and (b), a guard time necessary for switching from DL to UL and UL to DL is secured as a null symbol of irregular subframes. As shown in (a), one switching point can be secured within a 5 ms frame. In the case of (b), 16e and 16m coexist within a 5ms frame, while existing legacy systems such as IEEE 802.16 e system), it is possible to secure a plurality of switching points. Existing legacy systems have a limited number of switching points within a 5ms frame. Using the proposed frame structure, a new 16m system can have two or more switching points while limiting the switching point to one for legacy systems. Advantages can be gained in terms of latency such as HARQ (Hybrid Automatic Repeat reQuest).

7 is a diagram illustrating a superframe structure including subframes using various CP sizes in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 7, in the structure proposed in the present invention, all the CP sizes can be used without any restriction on the 16m zone subframe. In other words, the subframe supporting the legacy system is fixed at 1/8 of the CP size, but the subframe transmitting the remaining 16m can use the CP size differently regardless of the legacy system, thereby enabling more flexible communication system design .

For example, when supporting a legacy system in a femtocell using a 1/32 CP size, as shown in FIG. 7 (a), a subframe used by a legacy system maintains a 1/8 CP size, It can be seen that the CP size of the subframes can be configured as 1/4 or 1/32. That is, since the part for transmitting the broadcast message of the superframe must be receivable in any circumstance, the subframe is composed of 1/4, which is the longest CP size possible, and the remaining data transmission part is formed of the CP size suitable for the femtocell, 1/32 A subframe can be constructed. As another example, a macro cell using a 1/4 CP size instead of the femtocell or a frame for transmitting a message for broadcasting may be similarly configured. In this case, the sub-frame portion used by the legacy system maintains 1/8 CP size, and all sub-frames using 1/32 CP of the femtocell are replaced with sub-frames using 1/4 CP size do.

As shown in FIG. 7 (b), when a general mobile cell and a relay base station support an area supported by a general mobile cell and a relay base station, . ≪ / RTI > However, because the cell size supported by the relay base station is much smaller than the cell size supported by a typical mobile base station, a shorter CP size can be used. Therefore, the part where the legacy system and the mobile base station communicate with the terminal is configured as a subframe using 1/8 CP size, and the part where the relay base station and the terminal communicate with is configured as a subframe using 1/32 CP have.

(TDD, FDD, Half-duplex FDD, HDD (Hybrid Division Duplex), and the like) according to the level required by each wireless communication service, , They can be freely arranged and used in one frame. Also, even if different CP sizes are used between adjacent cells, there is almost no interference caused by different CP sizes. In case of TDD, since DL and UL are operated in subframe units, DL / UL collision can be prevented. Even if the CP sizes used in the adjacent frequency bands are different from each other, the influence thereon is negligible. In the case of TDD, DL and UL may be adjusted in subframe units so that DL / UL collisions do not occur. The configuration information (e.g., order, CP size, etc.) of the subframes having the various CP sizes is notified in a superframe header or a downlink control channel having a similar function. Thus, Frames can be configured and communicated.

8 is a diagram illustrating an example of a superframe structure composed of regular subframes including only a fragment OFDM symbol having a size of 1.0 in a wireless communication system according to an embodiment of the present invention. Here, the superframe is designed by applying the same basic numbers as possible for commonality with the existing design. When the fragment OFDM symbol size is 1.0, there is no exception signal processing structure for processing a fragment OFDM symbol having a size of 0.5 or 0.25 in the FFT, so that a signal processing method becomes simpler.

8, a 20 ms super frame 801 is composed of four frames 802, and one frame 802 is divided into four semi-frames 803 and a guard time 804 And one semi-frame 803 is composed of two sub-frames 805 having the same or different lengths. In the following description, it is assumed that the one semi-frame 803 includes two sub-frames 805 as described above. However, it is needless to say that the one semi-frame 803 may include a larger number of sub-frames 805. At this time, the number of OFDM symbols in one semi-frame 803 or sub-frame 805 can be variously changed according to the channel environment. That is, one semi-frame 803 can accommodate 11 OFDM symbols, 12 OFDM symbols, 13 OFDM symbols, and the like according to the size of the CP.

That is, when a 1/8 CP size is required as in a legacy system, two types of 0 subframes having 6 OFDM symbols are matched and have 12 OFDM symbols all having the same length, as shown in FIG. 8 Semi-frames can be configured. Here, when a subframe having the same length is constructed by using only a fragment OFDM symbol having a size of 1.0, one subframe length may not satisfy the TTI (Transmit Time Interval) required by the system. In this case, although the lengths are different, the subframes are paired to form a semi-frame having a constant length, and the CP size is changed based on the semi-frame, or DL / UL conversion or UL / DL conversion of the TDD system is performed do. For example, when only a small CP size (1/32) as in the femtocell is required as shown in FIG. 8, a Type 1 subframe having 6 OFDM symbols and a Type 1 subframe having 7 OFDM symbols To form a semi-frame having 13 OFDM symbols having the same length. On the contrary, when a large CP size (1/4) as in a macro cell is required, a Type 0 subframe having 5 OFDM symbols and a Type 1 subframe having 6 OFDM symbols are paired with each other and 11 OFDM symbols having the same length are matched You can configure a semi-frame with At this time, the Type 0 subframe and Type 1 subframe must satisfy the TTI required by the system.

The reason why the subframes or the semi-frames are equal in length is to make DL / UL collision interference in the TDD system as easy as possible, while allowing OFDM symbols having various lengths of CP to coexist in one communication system. This structure can also easily accommodate any duplex structure for relay communication or for peer-to-peer communication, and can communicate with two different communication systems (e.g., 802.16e systems and 802.16 m systems) can easily coexist.

9 is a diagram illustrating a superframe structure including semi-frames using various CP sizes in a wireless communication system according to an embodiment of the present invention. In the structure proposed in the present invention, all the CP sizes can be used without any restriction on the basis of the semi-frame length because the semi-frames are all fixed in length, and a semi-frame designed to have the DL / It can be seen that it can be handled easily by standard.

Referring to FIG. 9, in a super frame structure that provides TDD while accommodating a short OFDM symbol, one frame is composed of a regular sub-frame, an irregular sub-frame, and a guard time. That is, regular subframes are used irrespective of the type in most DL and UL sections constituting one frame, and irregular subframes are used irrespective of the type only in a portion where a transition from DL to UL or UL to DL is required To secure the necessary guard time when switching from DL to UL or from UL to DL. In this case, the guard time is ensured by constructing the last subframe of the semi-frame into an irregular subframe similarly to the case of using a fragment OFDM symbol having a size smaller than 1.0. At this time, the NULL symbol of the irregular subframe is firstly written using a short OFDM symbol having a size of 1.0. The frame provides the same semi-frame size, so even if there is more than one switching point for DL / UL switching, the frame changes in units of semiframes, so that no interference occurs due to non-synchronization of subframes. For example, referring to FIG. 9A, it can be seen that two DL / UL switching points can be secured within a 5 ms frame based on a semi-frame.

Although not shown in the drawings, a superframe structure that provides FDDs composed of semi frames having the same length by collecting different types of subframes can be designed similarly to a superframe structure that provides TDD. In this case, unlike a frame that provides TDD There is no need to use irregular subframes because switching from DL to UL and from UL to DL is not necessary.

In FIG. 9, the areas are divided into an 802.16e system and an 802.16m system for the sake of illustration. However, even if it is assumed that the areas where the CP sizes are differently used in a single communication system (for example, an 802.16m single system) It is acceptable. For example, if a femtocell using a 1/32 CP size supports a legacy system, the semi-frame used by the legacy system is maintained at 1/8 CP size as shown in FIG. 9 (b) The CP size of the semi-frames may be 1/4 or 1/32. That is, since the part for transmitting the broadcast message of the superframe must be receivable in any circumstance, a semi-frame is formed with 1/4, which is the longest possible CP size, and the remaining data transmission part is divided into 1/32 To form a semi-frame. As another example, a macro cell using a 1/4 CP size instead of the femtocell or a frame for transmitting a message for broadcasting may be similarly configured. In this case, the semi-frame portion used by the legacy system is maintained at 1/8 CP size, and the semi-frame using 1/32 CP of the femtocell is replaced with the semi-frame using 1/4 CP size .

In addition, when a general mobile cell and an area supported by a relay base station are supported together, a general mobile cell can constitute a subframe with a size of 1/8 CP like a conventional legacy system, as shown in FIG. 9 (c) . However, because the cell size supported by the relay base station is much smaller than the cell size supported by a typical mobile base station, a shorter CP size can be used. Therefore, the part where the legacy system and the general mobile base station communicate with the terminal is configured as a subframe using 1 / 8CP size, and the part where the relay base station and the terminal communicate with each other can be configured as a subframe using 1/32 CP size have. In this case as well, since the part for transmitting the broadcast message of the superframe must be receivable under any circumstances, a semi-frame is formed with a maximum CP size of 1/4.

In addition to the above examples, it is possible to freely arrange the semi-frames having a proper CP size according to the level required by each wireless communication service in a frame regardless of the duplex method. A semi-frame concept of the same length is introduced so that a fragment OFDM symbol having a size of 1.0 can be easily used for each unit time, and the configuration information of the various types of subframes constituting the semi-frame (E.g., order, CP size, number of OFDM symbols different for each type, etc.) is informed by a superframe header or a downlink control channel having a similar function, thereby forming a semi frame suitable for a communication service in a super frame or frame unit .

Since the semi-frame is a symbol time sorting concept that allows a short OFDM symbol to be easily used for each unit time, the concept can be further diversified. 9 (b) and 9 (c), for example, it is seen that the semi-frame 3 is composed of OFDM symbols having the same CP size, and the subframe types constituting the semi-frame 3 are the same have. 9 (b) and (c) coexist in one communication system (that is, when the characteristics and order of the subframes constituting the semiframe of the specific order are completely identical) , All OFDM symbol times are aligned with respect to the Type 0 subframe of the semi-frame 3 (that is, with reference to the subframe in a specific order of the semi-frame of the specific sequence). Therefore, it is possible to perform DL / UL conversion based on the type 0 subframe of the semi-frame 3, to perform relay communication, an area for peer-to-peer communication, or two different communication systems (e.g., 802.16e system and 802.16 m system) can coexist.

In addition, by using the fact that the lengths of the subframes having the same length and the length of the subframes having the same length are different from each other, for example, most of the 5 ms frames are composed of the same semiframe, It is also possible to configure sub-frames of different types. 10 and 11 are diagrams showing an example of a superframe structure composed of regular subframes including only a fragment OFDM symbol having a size of 1.0 in the wireless communication system according to the embodiment of the present invention in the 8.75 MHz band and the 7 MHz band to be. Referring to FIGS. 10 and 11, the last subframe of the 5 ms frame can not be expected to have time alignment at the symbol level due to the number of symbols included according to the CP size, but the previous semi- Even if symbols are included, time alignment is possible at least at the semi-frame level. Therefore, it is possible to perform DL / UL conversion based on the time alignment, or to use an area for relay communication, an area for peer-to-peer communication, or two different communication systems (for example, an 802.16e system and an 802.16m system) .

The configuration information (e.g., order, CP size, number of OFDM symbols different for each type, etc.) of the various types of subframes constituting the semi-frame and the DL / UL switching point and the relay communication Area information, and area information for peer-to-peer communication are notified in a superframe header or a downlink control channel having a similar function, thereby forming a semi-frame and a subframe suitable for a communication service on a superframe or frame basis and communicating .

On the other hand, the horizontal axis of the frame is displayed as a time axis in symbol units, and the vertical axis is displayed as a frequency axis in units of subchannels. The subchannel refers to a bundle of a plurality of subcarriers, and the carriers constituting each subchannel may be adjacent to each other or scattered. A subchannel consisting of scattered carriers is called a Distributed Resource Block (DRB), and a subchannel consisting of neighboring carriers is called a Localized Resource Block (LRB) Quot;). That is, a case where carriers belonging to a resource block (hereinafter referred to as 'RB') are scattered on the frequency axis is referred to as DRB, and a case where neighboring carriers are referred to as LRB. Herein, the RB is a minimum radio resource unit for dividing radio resources used for downlink data transmission and uplink data transmission. Each RB includes a plurality of carriers on the frequency axis and one or a plurality of symbols on the time axis.

In general, the mobile radio channel has the characteristics of frequency selective fading with multipath fading, while a specific band on the frequency axis has a high channel gain while another band has a characteristic of low frequency channel selective fading. That is, when the moving speed of the terminal is slow, for example, when the user moves on foot, the channel gain slowly varies in each band, so that the terminal selects a specific band having a relatively large channel gain and notifies the base station of information on the selected band A frequency selective scheduling gain can be obtained by allowing the base station to transmit data in a transmission mode having a high data rate in the specific band. In this case, since the radio resources belonging to the band selected by the terminal are not scattered on the frequency axis but exist in the corresponding band, the base station allocates the LRB to the corresponding terminal. On the other hand, when the UE moves at high speed and the channel changes rapidly or information about the selected band is not received from the UE, the BS can not use frequency selective scheduling. In this case, in order to obtain frequency diversity, the base station allocates DRBs, which are composed of carriers dispersed in terms of frequency, to the UEs.

12 and 13 are diagrams illustrating a method of designing a DL resource block according to a basic pilot pattern in a wireless communication system according to an embodiment of the present invention. Here, the DL resource block includes a fragment OFDM symbol and has a variable number of OFDM symbols (5, 5.5, 6, 6.25, 6.5, etc.).

Referring to FIG. 12, a basic subchannel (or frequency) -time resource block (e.g., 12x5) for DL is designed by designating LRB, DRB, and pilot according to the respective ratios, Increase DRB fragment or LRB fragment. It is also possible to gather the dotted pieces that have been painted with dots to create a new DRB or LRB. Here, the pilot is a general and a dedicated pilot, and designates a fixed number of pilots at a predetermined position according to a basic pilot pattern. When data and pilot symbols are transmitted over 864 subcarriers on the basis of 1024 subcarriers, assuming that the number of data subcarriers per RB is 48, the leftmost figure shows that when the number of data subcarriers per LRB is 72, the number of DRBs is 9, As the CP size decreases and the number of OFDM symbols increases, it can be seen that the number of DRBs is increased to 72, or the number of DRBs increases to 36 or the number of LRBs increases to 108.

Referring to FIG. 13, there is a difference in that DRBs are generated by fragmenting LRBs of FIG. 12 and combining resource fragments in various LRBs in the same manner as FIG. For example, the DBR can be generated by combining resource fragments dispersed in LRBs composed of several fragments in a frequency band using a permutation scheme. By doing so, the frequency diversity can be maximized.

14 is a diagram illustrating a method of designing a DL resource block according to an extended pilot pattern in a wireless communication system according to an embodiment of the present invention. Here, the DL resource block includes a fragment OFDM symbol and has a variable number of OFDM symbols (5, 5.5, 6, 6.25, 6.5, etc.).

Referring to FIG. 14, when designing a resource block using the extended pilot pattern, a DRB fragment may be switched to a pilot in a resource block design according to a basic pilot pattern, as needed. That is, a part of the DRB fragment used for data transmission can be additionally utilized as a pilot, thereby improving channel estimation performance. 14 are modified according to the extended pilot pattern (basic pilot pattern x 2) in the resource block design of FIG. 12, and the lower four pictures are shown as resources Block design is modified according to the extended pilot pattern (basic pilot pattern x 2). Likewise, the two upper right figures are views obtained by modifying the resource block design of FIG. 12 according to the extended pilot pattern (basic pilot pattern 3), and the lower two pictures are modified by expanding the resource block design of FIG. 13 (Basic pilot pattern x 3).

15 and 16 are diagrams illustrating a UL resource block design method in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 15, the UL resource block of the tile structure is designed to generate 1, 0.5, and 0.25 short OFDM symbols, like DL. The UL resource block of the tile structure is designed by designating LRB and DRB according to the respective ratios, and each LRB and DRB can be used not only as data but also as a dedicated pilot. Herein, the UL resource block is designed in consideration of a location of a dedicated pilot in a tile serving as a basic unit of UL resource block generation, thereby generating a UL resource block including a short OFDM symbol by combining a plurality of tiles.

Referring to FIG. 16, the UL resource block of the tile structure can be designed by collecting the tiles of the adjacent subcarriers and generating the LRB. Alternatively, When 48 subcarriers are collected, DRB may be generated.

17 is a flowchart illustrating a procedure of a transmission method for accommodating CPs of various lengths of a transmission apparatus in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 17, in step 1701, the transmitting apparatus codes and modulates information data from an upper layer according to a predetermined modulation level. Then, in step 1703, the transmitter generates an OFDM symbol of a variable size by performing IFFT on the encoded and modulated frequency-domain data, and transmits the generated variable-length OFDM symbol in step 1705.

Here, the transmitting apparatus uses a N / M size IFFT operator to obtain a short OFDM symbol, that is, an OFDM symbol set {A [n]} of N / M size (where n = 0, 1, ) -1). Here, N is an IFFT size for generating a reference OFDM symbol, and M = 1, 2, 4 ... (i.e., M = 2 ^k , where k = 0, 1, 2, 3, Is a parameter for making a symbol size such as N / 2, N / 4 or the like. Alternatively, the N / M sized OFDM symbol may be generated using an N-sized IFFT operator. For this, the transmitting apparatus generates N sequences by appropriately inserting 0 into N / M sequences, performs IFFT operation using an N size IFFT operator, and then selects only N / M sequences Thereby generating OFDM symbols of N / M size.

Thereafter, the transmitting apparatus terminates the algorithm according to the present invention.

18 is a flowchart illustrating a procedure of a receiving method for receiving CPs of various lengths of a receiving apparatus in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 18, the receiving apparatus checks whether or not a variable-size OFDM symbol is received in step 1801. When the variable-length OFDM symbol is received, the receiving apparatus converts the received variable-length OFDM symbol into an FFT And converts it into data in the frequency domain. Then, in step 1805, the receiving apparatus selects data of subcarriers to be actually received from the frequency-domain data. In step 1807, the receiving apparatus demodulates and decodes the selected data according to a predetermined demodulation level to recover original information data . Here, the original information data may be restored by using an N / M size FFT operator for the received N / M sequences, or N sequences may be generated by repeating the received N / M sequences M times, Size FFT operator.

Thereafter, the receiving apparatus terminates the algorithm according to the present invention.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

1 is a block diagram showing the configuration of a transmitting / receiving apparatus in a wireless communication system according to the present invention;

2 is a diagram showing a superframe structure composed of regular subframes including a fragment OFDM symbol in a wireless communication system according to an embodiment of the present invention;

3 is a diagram illustrating a superframe structure composed of irregular subframes including a fragment OFDM symbol in a wireless communication system according to an embodiment of the present invention;

4 is a diagram illustrating a superframe structure for providing TDD while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention;

5 is a diagram illustrating a superframe structure for providing FDD while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention;

6 is a diagram illustrating a superframe structure that provides IEEE 802.16e / 16m coexistence while accommodating a short OFDM symbol in a wireless communication system according to an embodiment of the present invention;

7 is a diagram illustrating a superframe structure including subframes using various CP sizes in a wireless communication system according to an embodiment of the present invention.

8 is a diagram illustrating an example of a superframe structure composed of regular subframes including only a fragment OFDM symbol having a size of 1.0 in a wireless communication system according to an embodiment of the present invention;

9 is a diagram illustrating a superframe structure including semi-frames using various CP sizes in a wireless communication system according to an embodiment of the present invention.

10 is a diagram illustrating an example of a superframe structure composed of regular subframes including only a fragment OFDM symbol having a size of 1.0 in a wireless communication system according to an embodiment of the present invention in the 8.75 MHz band;

11 is a diagram illustrating an example of a superframe structure composed of regular subframes including only a fragment OFDM symbol having a size of 1.0 in a wireless communication system according to an embodiment of the present invention in the 7 MHz band;

12 and 13 are diagrams illustrating a method of designing a DL resource block according to a basic pilot pattern in a wireless communication system according to an embodiment of the present invention.

14 is a diagram illustrating a method of designing a DL resource block according to an extended pilot pattern in a wireless communication system according to an embodiment of the present invention.

15 and 16 illustrate a UL resource block design method in a wireless communication system according to an embodiment of the present invention.

17 is a flowchart showing a procedure of a transmission method for accommodating CPs of various lengths of a transmission apparatus in a wireless communication system according to an embodiment of the present invention; and

18 is a flow chart illustrating a procedure of a receiving method for accommodating CPs of various lengths of a receiving apparatus in a wireless communication system according to an embodiment of the present invention.

Claims (32)

A transmitting apparatus in a wireless communication system, A modulator for generating transmission symbols constituting a frame, And an RF (Radio Frequency) processor for transmitting the transmission symbols, The frame includes a first sub-frame composed of symbols having a CP (Cyclic Prefix) of a first length and a second sub-frame composed of symbols having a CP of a second length, a guard time time, The CP of the first length is a CP for communication in the cell of the first size, Wherein the CP of the second length is a CP for communication in a cell of a second size. The method according to claim 1, Wherein the cell of the first size is a macrocell and the cell of the second size is a femtocell. The method according to claim 1, Wherein the first size cell is a general mobile cell and the second size cell is a cell supported by a relay base station. The method according to claim 1, At least one of a last one symbol of at least one subframe of the frame, a whole of the last plurality of symbols, and a portion of the last plurality of symbols comprises a null symbol. 5. The method of claim 4, Wherein at least one subframe of the frame is a subframe in which an uplink (DL) is switched to an uplink (DL) or a downlink (DL) is switched to a UL. 5. The method of claim 4, Wherein the symbol constituted by the null symbol is used as a guard time for switching from an uplink (UL) to a downlink (DL) or for switching from a DL to UL. 5. The method of claim 4, Wherein the null symbol of the one subframe comprises a fractional orthogonal frequency division multiplexing (OFDM) symbol. The method according to claim 1, Wherein the length of the first sub-frame and the length of the second sub-frame are the same. delete The method according to claim 1, Wherein the frame is comprised of one or more subframes supporting an IEEE 802.16e system and one or more subframes supporting an IEEE 802.16m system. The method according to claim 1, The frame may include one or more subframes supporting a legacy system, one or more subframes supporting a femtocell, one or more subframes supporting macrocells, one or more subframes for transmitting messages for broadcasting, one supporting a general mobile cell And at least one subframe supporting the relay, and at least one subframe supporting the relay. The method according to claim 1, Two or more than three subframes constitute one semiframe and all the semiframes in the frame have the same length. 13. The method of claim 12, Wherein the lengths of two or more subframes constituting one semi-frame are equal to or different from each other. 13. The method of claim 12, Wherein the TDD system performs DL / UL switching based on the subframe in the specific order of the semi-frame or in the specific order of the semi-frame. 13. The method of claim 12, Wherein the CP length is changed on a semi-frame basis or on a sub-frame basis in a specific order of a semi-frame in a specific order. 13. The method of claim 12, Characterized in that the frame comprises at least one semi-frame supporting the IEEE 802.16e system and at least one semi-frame supporting the IEEE 802.16m system. 13. The method of claim 12, The frame may include one or more semi-frames supporting a legacy system, one or more semi-frames supporting a femtocell, one or more semi-frames supporting macrocells, one or more semi-frames for transmitting messages for broadcasting, One or more semi-frames, one or more semi-frames, one or more semi-frames supporting relays. The method according to claim 1, Further comprising a code and a modulator for coding and modulating the information data from the upper layer according to a predetermined modulation level and outputting the code, Wherein the modulator outputs an OFDM (Orthogonal Frequency Division Multiplexing) symbol of variable size by performing Inverse Fast Fourier Transform (IFFT) on data in a frequency domain from a code and a modulator. 19. The apparatus of claim 18, wherein the modulator comprises: And outputs a K size OFDM symbol using a K size IFFT operator. 19. The apparatus of claim 18, wherein the modulator comprises: N sequences are generated by properly inserting 0s into the N / M sequences, IFFT operations are performed using N size IFFT operators, N / M sequences are output, and N / M size OFDM And outputs a symbol. A transmission method in a wireless communication system, Generating transmission symbols constituting a frame, And transmitting the transmission symbols, The frame includes a first sub-frame composed of symbols having a CP (Cyclic Prefix) of a first length and a second sub-frame composed of symbols having a CP of a second length, a guard time time, The CP of the first length is a CP for communication in the cell of the first size, Wherein the CP of the second length is a CP for communication in a cell of a second size. 22. The method of claim 21, Wherein the cell of the first size is a macro cell or a general mobile cell and the cell of the second size is a cell supported by a femtocell or a relay base station. 22. The method of claim 21, Coding and modulating information data from an upper layer according to a predetermined modulation level, Further comprising the step of performing Inverse Fast Fourier Transform (IFFT) on the encoded and modulated frequency-domain data to generate a variable-size Orthogonal Frequency Division Multiplexing (OFDM) symbol, The OFDM symbol generation process includes: Generating N sequences by appropriately inserting 0 into N / M sequences; Performing an IFFT operation on the generated N sequences using an N-sized IFFT operator; And generating N / M size OFDM symbols by selecting N / M sequences out of the N sequences. A receiving apparatus in a wireless communication system, An RF (Radio Frequency) processor for receiving symbols, And a demodulator for demodulating the symbols constituting the frame, The frame includes a first sub-frame composed of symbols having a CP (Cyclic Prefix) of a first length and a second sub-frame composed of symbols having a CP of a second length, a guard time time, The CP of the first length is a CP for communication in the cell of the first size, Wherein the CP of the second length is a CP for communication in a cell of a second size. 25. The method of claim 24, Wherein the cell of the first size is a macro cell or a general mobile cell and the cell of the second size is a cell supported by a femtocell or a relay base station. A receiving method in a wireless communication system, Receiving symbols, And demodulating the symbols constituting the frame, The frame includes a first sub-frame composed of symbols having a CP (Cyclic Prefix) of a first length and a second sub-frame composed of symbols having a CP of a second length, a guard time time, The CP of the first length is a CP for communication in the cell of the first size, Wherein the CP of the second length is a CP for communication in a cell of a second size. 27. The method of claim 26, Wherein the cell of the first size is a macro cell or a general mobile cell and the cell of the second size is a cell supported by a femtocell or a relay base station. 27. The method of claim 26, Transforming the received variable-length OFDM symbol into frequency-domain data by FFT (fast Fourier transform) Selecting data of subcarriers to be actually received from the data in the frequency domain and demodulating and decoding the selected data according to a predetermined demodulation level, The FFT calculation process includes: An FFT operation is performed using the K-size FFT operator for the received K sequences, or N sequences are generated by repeating the received N / M sequences M times, and an FFT operation is performed using an N-sized FFT operator . ≪ / RTI > 25. The method of claim 24, At least one of a last one symbol of at least one subframe of the frame, a whole of the last plurality of symbols, and a portion of the last plurality of symbols comprises a null symbol. 30. The method of claim 29, At least one subframe of the frame is a subframe in which an uplink (UL) to downlink (DL) or DL to UL transition is performed, Wherein the symbol consisting of the null symbol is used as a guard time for switching from an uplink (UL) to a downlink (DL) or for switching from a DL to UL. 30. The method of claim 29, Wherein the null symbol of the one subframe comprises a fractional orthogonal frequency division multiplexing (OFDM) symbol. 25. The method of claim 24, Further comprising a demodulator and a decoder for selecting data of subcarriers to be actually received from data in the frequency domain from the demodulator and demodulating and decoding the selected data according to a predetermined demodulation level, The demodulator performs FFT (Fast Fourier Transform) operation on a received variable-size OFDM symbol to output frequency-domain data, The demodulator, An FFT operation is performed using the K-size FFT operator for the received K sequences, or N sequences are generated by repeating the received N / M sequences M times, and an FFT operation is performed using an N-sized FFT operator Lt; / RTI >

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