KR100873196B1 - Method of primary user signal detection in transmission period in OFDM systems - Google Patents

Abstract

The present invention relates to a method for detecting a priority user signal while transmitting data between a node A and a node B in an orthogonal frequency division multiplexing (OFDM) system. A frame determination step of determining, by the determination unit, whether the number of remaining subcarriers other than the number of subcarriers required for data transmission for the entire frame is greater than the number of subcarriers forming a single frame; As a result of the determination by the determination unit, when the number of remaining subcarriers is larger than the number of subcarriers forming a single frame, the transmission unit moves the selected one of the plurality of frames to an empty frame when data is transmitted from the transmitter of the node A to the node B. Transmitting an empty frame; And a priority user signal detecting step of detecting a priority user signal over the entire frequency band of the empty frame by using the empty subcarrier area constituting the empty frame in the node A or the node B side. A priority first user signal detection method is provided.

Orthogonal Frequency Division Multiple, Node, Data, Subcarrier, Frame

Description

Method of primary user signal detection in transmission period in OFDM systems

1 is a flowchart of a method for detecting a priority user signal according to an embodiment of the present invention;

2 is a configuration diagram showing an embodiment in the case of having two frames;

3 is a block diagram showing an embodiment of a frame structure;

4 is a configuration diagram of an embodiment of an empty slot unit transmitting step S150 of FIG. 1;

5 to 6 is a configuration diagram of an embodiment related to the subcarrier allocation step (S160) of FIG.

7 is a block diagram of an embodiment of allocating a residual subcarrier over one or more frames;

8A to 8B are configuration diagrams of an embodiment for transmitting with or without a pilot signal in an empty subcarrier region;

9A to 9B are diagrams illustrating an embodiment of an empty subcarrier allocation in a next frame when a command signal is transmitted to a transmitter after first user detection;

10 is a schematic diagram of a system for the method of FIG.

<Explanation of symbols for main parts of the drawings>

110 Judgment 120 Transmission

130 ... detector

The present invention relates to a method for detecting a priority user signal when transmitting data in an orthogonal frequency division multiplexing (OFDM) system. More particularly, the present invention relates to an authorized priority of a corresponding frequency band using an idle frequency band, which is an empty subcarrier band. A priority signal detection method for detecting a user signal.

In general, in a wireless communication system such as an ultra wide band (UWB), a transmission frequency band is shared with an existing preferred user using the corresponding frequency.

Here, when sharing the transmission frequency band, in order not to interfere with the existing preferred user, there is a method for transmitting an unlicensed user signal at a lower transmission power than the existing preferred user signal. Since there is a problem that causes significant interference to the priority user signal, the frequency band should be made empty while the priority user signal uses the transmission frequency band.

That is, in such a wireless communication system, as a principle of emptying the corresponding frequency band by the unauthorized user, a method of detecting whether the priority user signal is using the corresponding frequency band is used, which is the corresponding frequency. It is to comply with the basic rule that the preferred user who pays the fee for the use of the band does not cause data interference and its damage.

Currently, a method for detecting a priority user signal can be generally divided into energy detection, shape detection, and the like. When the priority user signal is an analog signal instead of a digital signal, the above-described energy detection is used.

In the case of using such energy detection, the priority user may not be classified as an orthogonal function between a data signal used by an unauthorized user using a Cognitive Radio Wireless Communication System and the priority user signal. There is a problem that it is difficult to detect a signal.

To this end, it is common for an unauthorized user, such as a rest period, to stop transmitting a signal every period of time without transmitting a data signal to detect the preferential user signal over the entire frequency band during the pause period. .

This method has the advantage of detecting the priority user signal more accurately, but if the priority user signal comes in immediately after the idle period, i. First of all, there is a disadvantage of not detecting a user signal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and is an orthogonal signal that can effectively detect a priority user signal using an empty subcarrier band, that is, an idle frequency band, even during an data transmission period other than an idle period from an unauthorized user side. An object of the present invention is to provide a method for detecting a priority user signal in data transmission in a frequency division multiplexing system.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

In the orthogonal frequency division multiplexing system of the present invention for achieving the above object, the priority user signal detection method includes transmitting data between a node A and a node B in an orthogonal frequency division multiplexing (OFDM) system. The present invention relates to a method for detecting a priority user signal, wherein the number of remaining subcarriers other than the number of subcarriers required for data transmission is greater than the number of subcarriers forming a single frame for a plurality of all frames sequentially transmitted over time. A frame determining step of determining whether the determining unit is large; When the determination unit determines that the number of the remaining subcarriers is greater than the number of subcarriers forming the single frame, the transmitter selects one of the plurality of frames when the data is transmitted from the transmitter of the Node A side to the Node B side. An empty frame transmission step of transmitting a frame of the frame to an empty frame state; And a priority user signal detecting step of detecting the priority user signal over the entire frequency band of the empty frame by using the empty subcarrier area constituting the empty frame in a detection unit on a node A or node B side.

Further, in the frame determining step, when the number of the remaining subcarriers is smaller than the number of subcarriers forming the single frame, the number of the remaining subcarriers for the single frame including a plurality of OFDM slot units is determined. An OFDM slot unit determination step of determining, by the determination unit, whether the number of subcarriers forming a single OFDM slot unit is greater than the number of subcarriers; And when the determination unit determines that the number of the remaining subcarriers is greater than the number of subcarriers forming the single OFDM slot unit, the transmitting unit transmits the plurality of OFDMs when the data is transmitted from the transmitting unit on the node A side to the node B side. The method may further include an empty slot unit transmission step of transmitting one selected OFDM slot unit among slot units in an empty OFDM slot unit state, wherein the priority user signal detecting step includes: detecting an empty subcarrier area of the detector unit forming the empty OFDM slot unit; The preferred user signal can be detected over the entire frequency band of the empty OFDM slot unit.

In the OFDM slot unit determination step, when the determination unit determines that the number of the remaining subcarriers is smaller than the number of subcarriers forming the single OFDM slot unit, the data transmission from the node A side to the node B side is performed. And a subcarrier allocation step in which the transmitter allocates the remaining subcarriers over different frequency bands in at least one OFDM slot unit on the single frame and then transmits an allocated subcarrier region to an empty subcarrier state. In the detecting of the user signal, the detector may detect the priority user signal using the empty subcarrier area.

In the subcarrier allocation step, the transmitter may allocate the remaining subcarriers over different bands within one selected OFDM slot unit or over different bands through a plurality of selected OFDM slot units.

Meanwhile, in the subcarrier allocation step, when the remaining subcarriers are not allocated within one frame over different bands through a plurality of OFDM slot units, the transmitter allocates the remaining subcarriers over one or more frames and then allocates them. The allocated subcarrier region can be transmitted in an empty subcarrier state.

In the detecting of the priority user signal, when the detection unit detects the priority user signal using the empty subcarrier area within the predetermined frame, while transmitting the predetermined frame among the plurality of frames on the transmitter side, The detector may include a first command signal for instructing an immediate stop of data transmission from the transmitter side, and an empty subcarrier area of the same frequency band in which the priority user signal is detected during the next frame transmission after the predetermined frame at the transmitter side. A second command signal for allocating a subcarrier area to an empty subcarrier area within the next frame and transmitting the second command signal or a subcarrier in the same frequency band as the empty subcarrier area in which the priority user signal is detected when the next frame is transmitted by the transmitter; One OFDM slot unit area to which area belongs The following may send the third command signal in the frame to be transmitted by sub-carriers assigned to the empty region toward the transfer part.

According to the present invention, the transmitter may transmit a pilot signal in the empty subcarrier region or transmit the pilot signal without including the pilot signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. It should be interpreted as meanings and concepts corresponding to the technical idea of the present invention based on the principle of definition.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 is a flowchart of a method for detecting a priority user signal according to an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment in the case of having two frames, FIG. 3 is a block diagram showing an embodiment of a frame structure, and FIG. 5 is a block diagram of an embodiment of a subcarrier allocation step S160 of FIG. 1, and FIG. 7 is a diagram illustrating a remaining subcarrier in one or more frames. It is a block diagram of the Example to allocate over.

8A to 8B are diagrams illustrating an embodiment of transmitting or not including a pilot signal in an empty subcarrier area, and FIGS. 9A to 9B are diagrams illustrating a next frame when a command signal is transmitted to a transmitter after first user detection. FIG. 10 is a block diagram of a system for the method of FIG. 1.

First, the present invention relates to a method for detecting a preferred user signal while transmitting data between Node A and Node B in an Orthogonal Frequency Division Multiplexing (OFDM) system.

The Node A refers to an apparatus for transmitting data information to the Node B through a radio interface based on a wireless communication system such as a Cognitive Radio Wireless Communication System, and the Node B ) Refers to a device that receives data information from the Node A through a wireless interface based on the wireless communication system.

Meanwhile, the frame referred to in the present invention refers to a collection of OFDM slot units as shown in FIG. 2 for transmitting the data except for a preamble and a header in a transport packet. it means.

2 illustrates an example in which two frames 200A and 200B are transmitted during data transmission, and one frame 200A or 200B includes 42 subcarrier areas in total. Each data can be sent. The horizontal axis 210A or 210B and the vertical axis 220A or 220B of one frame 200A or 200B have a total of seven time units and six frequency units as a time axis and a frequency axis, respectively. In addition, in FIG. 2, there are seven OFDM slot units divided by time units on a time axis, and one OFDM slot unit, that is, for example, the first OFDM slot unit 211A of FIG. 2 may have different frequency bands. It consists of seven subcarrier areas.

On the other hand, the data to be transmitted is transmitted over one single frame 200A or over a plurality of subsequent frames 200B, etc. having the same configuration as the frame 200A as shown in FIG. 2. 2 may be sequentially transmitted (in the case of FIG. 2, a data transmission example having two frames of frames A and B). Also, in each of the frames 200A and 200B, a subcarrier region in which data to be transmitted does not exist is divided into remaining subcarriers.

The configuration of the frame 200A shown in FIG. 2 is merely an embodiment, and a configuration of a frame having 64 subcarrier regions of an 8 × 8 array in data transmission is generally used, but the structure of such a frame The configuration is not limited to the above description, and the present invention will be described by taking an arbitrary frame structure as an example for convenience of description only.

Hereinafter, a method of detecting a priority user signal during data transmission in an orthogonal frequency division multiplexing system according to the present invention will be described with reference to FIGS. 1 to 10.

First, the determination unit 110 determines whether the number of remaining subcarriers other than the number of subcarriers necessary for the data transmission is present for a plurality of all frames sequentially transmitted over time (S100), wherein the number of the remaining subcarriers is determined. The determination unit 110 determines whether is greater than the number of subcarriers constituting the single frame (S110).

For example, two frames including frames A and B are used for data transmission as shown in FIG. 2, and each frame is in the form of a frame 300 having 42 subcarrier regions in the arrangement as shown in FIG. 2. When the number of subcarriers required for data transmission in Frame B is 10 and 20, respectively, the total number of subcarriers required for data transmission for the entire frame including Frames A and B is 30 (= 10 + 20). For the entire frame, the number of remaining subcarriers, which is the number of subcarriers except this, is 54 (= 84-30).

Next, when the determination unit 110 determines that the number of the remaining subcarriers is greater than the number of subcarriers forming the single frame, when the data is transmitted from the transmitting unit 120 of the node A side to the node B side. The transmitter 120 transmits one selected frame among the plurality of frames in an empty frame state (S120).

That is, in the above example, the number of the remaining subcarriers (54) is greater than the number of the subcarriers (42) forming the single frame, and in this case, 42 residual subcarriers of the 54 are used during the data transmission. Frame A, which is one of the selected frames A and B, may be transmitted in an empty frame state.

Here, the detection unit 130 of the node A or the node B detects the priority user signal over the entire frequency band of the empty frame by using the empty subcarrier region constituting the empty frame (S130).

That is, by transmitting the frame A as an empty frame, it is possible to detect whether there is a priority user signal being transmitted on the frame A region.

In this case, when the frame A is emptied, 10 subcarriers on the frame A, which are data to be transmitted through the frame A, are also emptied and sent, so in this case, the 10 subcarriers on the frame B which is the next frame after the frame A It may be configured to be allocated and transmitted in a manner such as random within the remaining subcarrier area (42-20 = 22), in this case, 12 (= 22-10) of the total remaining in the frame B after the allocation The subcarrier region may be finally left.

As described above, as the frame A is emptied, data that was previously transmitted through the frame A may be rearranged and transmitted in the remaining subcarrier area on the frame B.

Of course, this example can be applied to the same principle in the configuration in which data is transmitted through two or more frames.

According to the present invention, when the determination unit 110 determines in the frame determination step S110, the number of the remaining subcarriers is smaller than the number of subcarriers forming the single frame. For the single frame, the determination unit 110 determines whether the number of residual subcarriers is greater than the number of subcarriers forming a single OFDM slot unit (S140).

For example, two frames including frames A and B are used for data transmission as shown in FIG. 2, and each frame is in the form of a frame 400 having 42 subcarrier regions in an arrangement as shown in FIG. 4. If the number of subcarriers required for the data transmission is 40 and 36 in frame B and frame B, respectively, the total number of subcarriers required for data transmission for the entire frame including frames A and B is 76 (= 40 + 36). ), And the number of remaining subcarriers, that is, the number of subcarriers except for the entire frame, is 8 (= 84-76).

Here, the number of remaining subcarriers (8) is smaller than the number of subcarriers (42) constituting the single frame 400, and in this case, the number of remaining subcarriers (8) corresponds to the single OFDM slot unit of FIG. It is determined whether the number of subcarriers is greater than six (6).

When the determination unit 110 determines that the number of remaining subcarriers (eight) is greater than the number of subcarriers (six) forming a single OFDM slot unit, the transmitter of the node A side to the node B side. When transmitting the data, the transmitter 120 transmits one OFDM slot unit 410 selected from the plurality of OFDM slot units on the frame A in an empty OFDM slot unit state (S150).

That is, six of the eight remaining subcarriers are all allocated to the selected one OFDM slot unit 410, and then six allocated subcarrier regions 411, 412, 413, 414, 415 and 416 can be transmitted in the form of empty OFDM slot units as described above. have.

Here, of course, the remaining two remaining subcarriers may also be arbitrarily allocated to any subcarrier area among the other OFDM slot units 420 to 470 other than the selected one OFDM slot unit 410 that has already been allocated. In the case of the two allocated subcarrier areas 417 and 418 may also be transmitted in the form of empty subcarriers. The random allocation may be allocated over various frequency bands through the plurality of OFDM slot units 440 and 450 as shown in FIG. 4 or may be allocated over various frequency bands within one OFDM slot unit (one of 420 to 470). In addition, as shown in the example of FIG. 3, the plurality of OFDM slot units 310 and the like may be sequentially assigned 301 to 306 in time over various frequency bands.

In this case, in the first user signal detection step (S130), the detection unit 130 uses the empty subcarrier regions 411 to 416 forming the empty OFDM slot unit 410 to perform the empty OFDM slot unit 410. The priority user signal can be detected over the entire frequency band.

That is, as the selected one OFDM slot unit 410 is empty and transmitted, it is possible to detect the presence or absence of a priority user signal being transmitted on the empty OFDM slot unit 410.

In this case, when the one OFDM slot unit 410 is empty and transmitted, some subcarriers which are intended to be transmitted through the one OFDM slot unit 410 of the 40 subcarriers on the frame A are also empty and are sent. The subcarriers may be configured to be allocated and transmitted in a random manner or the like within the remaining subcarrier area on Frame B, which is the next frame after Frame A.

Meanwhile, as a result of the determination by the determination unit 110 in the OFDM slot unit determination step (S140), when the number of the remaining subcarriers is smaller than the number of subcarriers forming the single OFDM slot unit, the transmitter of the node A side ( 120, the transmitter 120 allocates the remaining subcarriers in different frequency bands in at least one OFDM slot unit on the single frame, and then allocates an allocated subcarrier area to an empty subcarrier. Transmit to state (S160).

For example, two frames including frames A and B are used for data transmission as shown in FIG. 2, and each frame is in the form of a frame 500 or 600 having 42 subcarrier areas in an arrangement as shown in FIG. 5 or 6. When the number of subcarriers required for the data transmission in the frame A and the frame B is 40, respectively, the total number of subcarriers required for the data transmission for the entire frame including the frames A and B is 80 (40 = 40 + 40). The number of remaining subcarriers, which is the number of subcarriers except this, is 4 (= 84-80).

Here, the number of remaining subcarriers (four) is smaller than the number (42) of subcarriers constituting the single frame 500 or 600, as well as the number of subcarriers constituting a single OFDM slot unit of FIG. 5 or 6 (6). Is less than

In this case, as shown in FIG. 5 or 6, after allocating the remaining subcarriers in different frequency bands in at least one OFDM slot unit on the single frame 500 or 600, the allocated subcarrier regions 511, 512, 513, and 514 are empty. Transmitted in the subcarrier state.

More specifically, during the subcarrier allocation step (S160), the transmitter 120 allocates the remaining subcarriers over different bands within the selected one OFDM slot unit 530 as shown in FIG. A plurality of OFDM slot units 510, 520, 530, and 540 selected together may be allocated over different bands.

The allocation over the different bands is for detecting the preferential user signal in more various bands, and the reason for passing through the various slot units is that the preferential user signal can be detected at various time points. To make it work. That is, the priority user signal may be detected on various frequency bands at the same time point, and the priority user signal may be detected on various frequency bands at various time points.

In this case, in the priority user signal detection step 130, the detection unit 130 may detect the priority user signal being transmitted on the empty subcarrier areas 511, 512, 513, and 514 using the empty subcarrier areas 511, 512, 513, and 514. .

In this case, when the allocated subcarrier regions 511, 512, 513 and 514 are emptied and transmitted in the form of an empty subcarrier region, some of the subcarriers intended to be transmitted through the allocated subcarrier regions 511, 512, 513 and 514 on the frame A are also emptied and transmitted. In this case, the some subcarriers may be configured to be allocated and transmitted in a random manner or the like within the remaining subcarrier area range on Frame B, which is the next frame after Frame A.

On the other hand, in the subcarrier allocation step (S160), when the remaining subcarriers are not allocated in one frame over different bands via a plurality of OFDM slot units, the transmitter 120 assigns one or more of the remaining subcarriers. After allocating over a frame, the allocated subcarrier region is transmitted in an empty subcarrier state.

For example, as shown in FIG. 7, two frames of frames A and B are used for data transmission, and each frame includes frames 700A and 700B having 12 subcarrier regions of the arrangement shown in FIG. 7. As a form, when the number of subcarriers required for the data transmission in frame A and frame B is 8 and 12, respectively, the total number of subcarriers required for data transmission for the entire frame including the frames A and B is 20 ( = 8 + 12), and the number of remaining subcarriers, that is, the number of subcarriers except this, becomes 4 (= 24-20).

However, in the case of FIG. 7, since the remaining subcarriers 711, 712, 713, 714 are allocated over different bands of all four frequency bands through a plurality of OFDM slot units 710A, 720A, 730A on frame A 700A. Since the OFDM slot unit of the frame A is not one unit, the remaining subcarriers that cannot be allocated are allocated to the subcarriers in the OFDM slot units 710B, 720B, and 730B of the frame B 700B, which is the next frame after the frame A 700A. It can then be transmitted to the empty subcarrier state.

Here, as shown in FIG. 7, the remaining subcarriers may be divided into two frames ('711, 712' / '713, 714') for each frame 700A and 700B. Alternatively, one or three ('711' / '712,713,714) may be allocated. ') Or three, one by one (' 711, 712, 713 '/' 714 ') can be assigned, of course.

As described above, the reason for allocating the empty subcarriers evenly in all frequency bands is to improve the overall band detection efficiency of the priority user signal by the detector 130 at all frequencies in the frame as described above.

On the other hand, in the first user signal detection step (S130) after the steps S120, S150 and S160, a predetermined frame (for example, frames A and B) of the plurality of frames (for example, frames A and B) on the transmitter 120 side. For example, when it is determined that the detection unit 130 detects a priority user signal using the empty subcarrier area within the predetermined frame (frame A) while transmitting frame A, that is, the empty subcarrier area is used. When it is determined that the priority user signal for performing data transmission exists on the empty subcarrier region, the detector 130 may be configured to take one of three actions selected from the following three toward the transmitter 120. Can be.

For example, when the priority user signal is detected, the detector 130 may transmit a first command signal for instructing immediate stop of data transmission from the transmitter 120 to the transmitter 120. . That is, as the priority user signal is detected, an interference factor acting on the priority user signal by the data of the unauthorized user is requested to immediately stop the data transmission operation performed on the transmission unit 120 side. It can be removed immediately.

In addition, as shown in FIG. 9A, when the transmission unit 120 transmits a next frame (frame B; 900B) after the predetermined frame (frame A; 900A), the priority user signal is detected. The transmitter transmits a second command signal for allocating a subcarrier region 912 of the same frequency band as the empty subcarrier region 911 to the empty subcarrier region 912 in the next frame (frame B; It may transmit to the (120) side.

That is, in this case, after the primary detection of the frame A 700A, the secondary detection of the priority user signal using the empty subcarrier region 912 of the same frequency band as that of the primary detection on the frame B 700B. By performing the re-execution, it is possible to increase the accuracy and reliability of the detection of the previously detected first user signal.

On the other hand, the detection unit 130, as shown in Figure 9b, the empty sub-carrier area 911, the first user signal is detected when the next frame (frame B; 900B) is transmitted from the transmitter 120 side And transmitting the third command signal for allocating one OFDM slot unit region 910 to which the subcarrier region 913 of the same frequency band belongs to the empty subcarrier region within the next frame (frame B; 900B). It may transmit to the unit 120 side.

That is, in this case, after the primary detection of the frame A 700A, on the frame B 700B, not only the empty subcarrier area 914 of the same frequency band as in the first detection, but also the empty subcarrier area 914. The secondary detection of the priority user signal using all other empty subcarriers 913,915, 916 in the OFDM slot unit region 910 transmitted at the same time point as Not only can the detection accuracy of the frequency band be improved, but the error of the detection frequency band at the same point in time can also be confirmed.

According to the present invention, the transmitter 120 transmits the pilot signal 802 to the empty subcarrier area 801 including the pilot signal 802 in step S120, S150 or S160, as shown in FIG. Likewise, the pilot signal can be transmitted without including the pilot signal. 8A or 8B illustrate a plurality of subcarrier types for each frequency band on one OFDM slot unit 810. The subcarriers include an empty subcarrier region 810. Referring to FIG.

In the case of FIG. 8A, as the pilot signal 802 is included and transmitted to the empty subcarrier region 801, the empty subcarrier using the pilot signal 802 is detected by the node A or node B detection unit 130. To facilitate channel measurement.

On the contrary, in the case of FIG. 8B, the empty subcarrier area 801 is transmitted without the pilot signal 802 in the empty subcarrier area 801, thereby maintaining the empty subcarrier area 801 in a cleaner state. Detection can be facilitated. That is, FIG. 8B is a case where the emphasis is placed on accurate detection of the priority user signal than on acquiring accurate channel information.

In the present invention as described above, the node A is fixedly described as a transmitter, and the node B is a receiver. However, this is merely an exemplary embodiment for convenience of explanation, and the node A and the node B are respectively transmitted to the transmitter and the receiver. It is not limited. That is, in consideration of bidirectional wireless communication, when the Node B is operated as a transmitter, the Node A may also operate as a receiver that receives data transmitted from the Node B side. It goes without saying that the same method as the priority user signal detection method of the present invention is simultaneously applied.

According to the present invention, since the remaining subcarrier region, which is an empty frequency band, is effectively allocated within a frame and then transmitted in the form of an empty subcarrier during data transmission, the priority user signal can be detected without interference by using the empty subcarrier region. If the priority user signal is detected, the priority user can be given immediate use priority.

In addition, as described above, the priority user signal can be detected during the period in which data is transmitted, that is, even during the idle period in which data transmission is not performed, so that the priority user signal can be detected without waiting for the idle period for detecting the priority user. There is an advantage that can be detected more quickly and accurately.

In the present invention as described above, in the time division duplexing (TDD) or frequency division duplexing (FDD) method, there is data to be transmitted from node A and no data to be transmitted to node A from other nodes. This is also applicable when there is no data to be transmitted in the node and there is data to be transmitted in the NodeB.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is described by the person of ordinary skill in the art to which the present invention pertains. Various modifications and variations are possible without departing from the scope of the appended claims.

According to the preferred user signal detection method for data transmission in the orthogonal frequency division multiplexing system according to the present invention, when there is an empty subcarrier region during data transmission, the corresponding empty subcarrier is effectively distributed in a frame and transmitted as an empty subcarrier type. By using the empty subcarrier region, the priority user signal can be effectively detected without interference and the detection accuracy of the priority user signal can be improved.

In addition, since the priority user signal can be detected even during the period in which data is transmitted instead of the idle period, the priority user signal can be detected more quickly and accurately without waiting for the idle period for the priority user detection.

Claims (7)

In the Orthogonal Frequency Division Multiplexing (OFDM) system, the present invention relates to a method for detecting a preferred user signal while transmitting data between Node A and Node B. A frame determining step of determining, by the determining unit, whether the number of remaining subcarriers other than the number of subcarriers necessary for the data transmission is greater than the number of subcarriers forming a single frame for a plurality of all frames sequentially transmitted over time; As a result of the determination by the determination unit, when the number of the remaining subcarriers is greater than the number of subcarriers forming the single frame, the transmitter of the node A side may transmit the data from the transmitter of the node A side to the node B side. An empty frame transmission step of transmitting a selected one of the frames to an empty frame state; And When the data transmission in the orthogonal frequency division multiplexing system, the detection unit of the node A side detecting the priority user signal over the entire frequency band of the empty frame using the empty subcarrier region constituting the empty frame First user signal detection method. According to claim 1, The determination result of the determination unit in the frame determination step, When the number of the remaining subcarriers is smaller than the number of subcarriers forming the single frame, whether the number of the remaining subcarriers is larger than the number of subcarriers forming a single OFDM slot for the single frame including a plurality of OFDM slot units An OFDM slot unit determination step determined by the determination unit; And When the determination unit determines that the number of the remaining subcarriers is greater than the number of subcarriers forming the single OFDM slot unit, the transmitting unit of the node A side may transmit the data from the transmitting unit of the node A side to the node B side. The method further includes a step of transmitting an empty slot unit for transmitting one selected OFDM slot unit among a plurality of OFDM slot units in an empty OFDM slot unit state. The priority user signal detection step, The detection unit of the node A side detects the preferential user signal over the entire frequency band of the empty OFDM slot unit by using the empty subcarrier region forming the empty OFDM slot unit. How to detect priority user signal. According to claim 2, The determination result of the determination unit in the OFDM slot unit determination step, When the number of the remaining subcarriers is smaller than the number of subcarriers forming the single OFDM slot unit, the transmitting unit of the node A side may transmit at least one of the at least one portion of the single frame during the data transmission from the transmitting unit of the node A side to the node B side. Subcarrier allocation step of allocating the remaining subcarriers in different OFDM bands in an OFDM slot unit and transmitting the allocated subcarrier region to an empty subcarrier state; The priority user signal detection step, And a detection unit on the node A side detects the priority user signal using the empty subcarrier region. The method of claim 3, wherein the subcarrier allocation step, Orthogonal frequency division, characterized in that the transmitter of the node A allocates the remaining subcarriers over different bands within one selected OFDM slot unit or across different bands through a plurality of selected OFDM slot units. Preferred user signal detection method for data transmission in multiple systems. The method of claim 4, wherein in the subcarrier allocation step, If the remaining subcarriers are not allocated in one frame over different bands through a plurality of OFDM slot units, the transmitter of the node A allocates the remaining subcarriers over one or more frames and then allocates the allocated subcarrier regions. A priority user signal detection method in data transmission in an orthogonal frequency division multiplexing system characterized by transmitting in an empty subcarrier state. The method according to any one of claims 1 to 5, wherein in the priority user signal detection step, When the detector on the node A side detects a priority user signal using the empty subcarrier area within the predetermined frame while the transmitter on the node A transmits a predetermined frame among the plurality of frames, The detection unit on the node A side is a first command signal for instructing an immediate stop on data transmission from the transmission unit on the node A side, and the priority user signal on the next frame transmission after the predetermined frame in the transmission unit on the node A side. A second command signal for allocating a subcarrier region having the same frequency band as the empty subcarrier region from which the signal is detected is transmitted to the empty subcarrier region within the next frame, or transmitting the next frame at the node A side to transmit the next frame Transmitting, by the node A side, a third command signal for assigning and transmitting one OFDM slot unit region belonging to the empty subcarrier region where the user signal is detected and a subcarrier region of the same frequency band as the empty subcarrier region within the next frame. Data transmission in an orthogonal frequency division multiplexing system characterized by Transmission priority user signal detection method. The method of claim 6, wherein the transmitting unit on the node A side, The first user signal detection method for transmitting data in the orthogonal frequency division multiplexing system comprising transmitting a pilot signal in the empty subcarrier region or transmitting the pilot signal without including the pilot signal.

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