KR20080084510A - Method for determining that at least one channel is available - Google Patents

Abstract

The present invention relates to a communication system, and more particularly to a method of determining whether a particular channel is available when multiple communication systems can coexist.

According to an embodiment of the present invention, a method of determining whether a specific channel is available when at least one communication system is capable of receiving at least one signal in the specific channel, and receiving the received signal and the at least one signal. Channel availability may be determined by determining whether the specific channel is available using at least one preamble information corresponding to each of the above communication systems.

Description

Method for determining that at least one channel is available}

1 is a flowchart for explaining a first embodiment of the present invention.

It is a figure for demonstrating 1st Embodiment of this invention.

3 shows an exemplary detection apparatus capable of carrying out the first embodiment of the present invention.

4 is a diagram for explaining a second embodiment of the present invention.

It is a figure for demonstrating 3rd Embodiment of this invention.

It is a figure for demonstrating 4th Embodiment of this invention.

It is a figure for demonstrating 5th Embodiment of this invention.

8 is a diagram for explaining a sixth embodiment of the present invention.

The present invention relates to a communication system, and more particularly to a method of determining whether a particular channel is available when multiple communication systems can coexist.

Recently, a wireless network between a relatively small number of digital devices in a confined space such as a home or a small work place to exchange audio or video data between the devices can be used. Network technology is being developed. WPAN can be used to exchange information between a relatively small number of digital devices at relatively close distances, enabling low power and low cost communication between digital devices.

Performing communication via wireless technology makes it possible to eliminate wires such as cables for connecting the devices. In addition, via wireless network communication between devices, it is possible to exchange data information directly between devices. Devices capable of communicating in the network include computers, PDAs, notebooks, digital TVs, camcorders, digital cameras, printers, microphones, speakers, headsets, bar code readers, displays, mobile phones, and the like. All digital devices can be used. have.

In the prior art as described above, an object of the present invention is to propose a method for determining the availability of the channel. It is also an object of the present invention to provide a method for checking whether there is a communication system in communication on a particular channel.

According to an aspect of the present invention, there is provided a method of determining whether a specific channel is available when at least one communication system is capable of receiving the at least one signal in the specific channel and the And determining whether the particular channel is available using the received signal and at least one preamble information corresponding to each of the at least one communication system.

The determining may include determining whether the specific channel is available through at least one correlation value generated by correlating the received signal with the at least one preamble information. In addition, the determining may determine that the specific channel is unavailable when the at least one correlation value exceeds a preset threshold. The determining may determine that the specific channel is available when the at least one correlation value does not reach a preset threshold.

Here, when the signal transmitted from the at least one communication system is strong in direction, the at least one communication system may transmit a signal corresponding to preamble information periodically for at least one or more directions.

In addition, the at least one preamble information, the original preamble signal of the at least one or more communication system may be filtered to correspond to the receiving side channel bandwidth. The down sampling may be performed on the received signal, and the determining may determine whether the specific channel is available using the down sampled signal and the at least one preamble information.

Further, when receiving signals from a plurality of channels in the receiving step, the determining step sequentially determines whether the plurality of channels are available using the signals received from the plurality of channels and the at least one preamble information. Can be determined.

In addition, when receiving signals from a plurality of channels in the receiving step, the determining step may simultaneously determine whether the plurality of channels are available using the signals received from the plurality of channels and the at least one preamble information. You can decide.

In addition, when receiving signals from a plurality of channels in the receiving step, the at least one or more preamble information may be configured in a pattern generated in consideration of all the signals received from the plurality of channels.

In the method, the method may further include measuring a period between the generated one or more correlation values. Here, in the determining step, when the measured period and the period information of the at least one or more communication systems match and match, it may determine that the specific channel is unavailable. The period information of the at least one communication system may be information about one of a period of broadcasting a scheduling message in the communication system and a period of transmitting a preamble signal in the communication system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description set forth below in conjunction with the appended drawings is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details to assist in a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. For example, the following description will focus on devices, preambles, and the like, but need not be limited to these terms, and the above device may have the same meaning even when referred to as any term such as an apparatus or an apparatus. In addition, the preamble may also have the same meaning when referred to as any term indicating information that can distinguish a communication system.

In some instances, well-known structures and / or devices may be omitted in order to avoid obscuring the concepts of the present invention, and may be represented in the form of block diagrams and / or flowcharts showing the core functions of each structure and / or device. have. In addition, the same components will be described with the same reference numerals throughout the present specification.

1 is a flowchart for explaining a first embodiment of the present invention.

The device first checks to see if there is a signal being transmitted on a particular channel to see if it can communicate over that particular channel. If there is no signal received by the device, it means that there is no communication system using a specific channel. In this case, communication can be performed through the specific channel.

If there is a signal being received by the device, check whether the received signal is a noise or a signal transmitted from a communication system using a particular channel. As a result of checking the signal received by the device, if the received signal is noise, it means that there is no communication system using a specific channel. In this case, communication can be performed through the specific channel.

As a result of checking the received signal from the device, if the received signal corresponds to the signal transmitted from the specific system, it means that there is a communication system using a specific channel. It is desirable to use another channel region.

Referring to FIG. 1, a method of determining whether to use a specific channel when a plurality of communication systems can coexist will be described in detail.

First, in step S10, the device entering the communication area and trying to communicate through a specific channel receives a signal transmitted on the specific channel.

In operation S11, at least one correlation value is calculated using the received channel signal and at least one preamble information known by the device receiving the signal. Step S11 is an example of a method that a device may perform to determine whether a received signal is a signal transmitted from a communication system using a particular channel or noise. Therefore, any information that can distinguish a communication system other than the preamble information can be used. In addition to calculating a correlation value, any method of knowing how much a signal matches another signal may be used.

In addition, the preamble information for calculating the correlation value corresponds to each of a plurality of communication systems that can coexist. In other words, each communication system has preamble information as one of information for identifying each communication system. If the communication system is different, it is possible to distinguish the communication system through the preamble by making the pattern of the preamble transmitted by the communication system different.

In addition, the device that wants to determine whether a specific channel is available, preferably knows the preamble information for each communication system in advance. The device may store preamble information of each communication system that can coexist in a memory provided in the device and use the same to determine whether to use a specific channel. In addition, the preamble information of each of the communication systems that can coexist if necessary from a specific scheduling entity may be used to determine whether to use a specific channel.

Finally, in step S12, it is determined whether the above specific channel is available through the calculated at least one correlation value. If the preamble information for each communication system known by the device is correlated with a signal received in a specific channel, the correlation value may be detected when the preamble information and the signal received in the specific channel match. When there is a large number of preamble information for a communication system known to a device, a correlation value is detected by sequentially or simultaneously correlating each of the plurality of preamble information with a signal received in a specific channel.

Correlation values will be detected only if the preamble information and the received signal coincide with each other when the result of the correlation between the plurality of preamble information and a signal received in a specific channel is ideal. Therefore, when a correlation value is detected, it is possible to know that a communication system corresponding to a preamble that generates the detected correlation value exists and determine that the specific channel is unavailable.

However, when a plurality of preamble information and a signal received in a specific channel are correlated, and a result is not ideal, some signals may be detected even if the preamble information and the received signal do not match. When a plurality of preamble information and a signal received in a specific channel are correlated, and a plurality of results are detected, this is regarded as a correlation value for each correlation.

When one or multiple correlation values are generated, the device may determine whether the particular channel is available through the generated correlation values. For example, when the generated correlation value exceeds a preset threshold, it is known that a communication system corresponding to the preamble used to generate the correlation value exists, and the specific channel may be determined to be unavailable. On the contrary, when the generated correlation value is smaller than the preset threshold, the received signal may be considered to be noise and may determine that a specific channel is available.

For example, when a plurality of correlation values are generated, it is known that a communication system corresponding to a preamble used to generate a correlation value corresponding to a maximum value among the generated correlation values exists, and the specific channel is used. You can decide to be impossible. Even in this case, it is known that there exists a communication system corresponding to the preamble used to generate the correlation value corresponding to the maximum value only when the correlation value corresponding to the maximum value among the generated correlation values exceeds the preset threshold. In this case, the specific channel may be determined to be unavailable. On the contrary, when the generated correlation values are smaller than the preset threshold, the received signal may be recognized as noise and it may be determined that a specific channel is available.

For example, if a received signal is correlated using a plurality of preamble information, but there is a preamble in which correlation values exceeding expectations, that is, a predetermined threshold or more, are detected, a communication system corresponding to the detected preamble exists. Knowing that, it is possible to determine that this particular channel is unavailable. On the contrary, if the generated correlation values are not detected or all are smaller than the preset threshold, the received signal may be recognized as noise and it may be determined that a specific channel is available.

Channel availability is determined as described above, and the present embodiment ends.

It is a figure for demonstrating 1st Embodiment of this invention.

Referring to FIG. 2, the procedure corresponding to steps S10, S11 and S12 of FIG. 1 will be described in more detail.

First, FIG. 2A shows signals received by a device to communicate using a specific channel. The signal received by the device includes a preamble. While other data may be received with the preamble signal, it is natural that the device may only receive the preamble to determine whether a particular channel is available.

2 (b) shows preamble information of a communication system, which is received by a device to communicate using a specific channel or stored in a memory provided in the device. As shown in (b), for example, three communication systems, namely, communication system A, communication system B, and communication system C may coexist, and the device is free of communication system A, communication system B, and communication system C, respectively. I know the emblem information. The device correlates the received signal with three known preamble information when the signal is received.

As shown in FIG. 2B, the device receives a plurality of signals from a specific channel and sequentially correlates the plurality of signals with preamble information of each of the communication system A, the communication system B, and the communication system C, respectively. The first two received signals are correlated with the preamble information of communication system A. Next, the two received signals are correlated with the preamble information of the communication system B. Finally, the two received signals are then correlated with the preamble information of communication system C.

2 (c) shows a result of correlating signals received by the device with preambles of the communication system known by the device. The result of correlating the signals received by the device and the preambles of the communication system known by the device through FIG. 2C is the result of correlating the two signals received and the preamble information of the communication system C. It can be confirmed that only detected. This indicates that the device is using the specific channel in communication system C. Therefore, in this case, the device may determine that the specific channel is not available, search for another channel, or use the specific channel if the specific channel is found to be available after a certain time.

In FIG. 2C, a result of correlating preambles of communication system A and communication system B is not detected. But this represents an ideal case. In practice, some small signals may be detected even if the received signals do not correspond to the preambles of communication system A and communication system B. In this case, it may be determined whether a specific channel is available through the methods described in step S12 of FIG. 1.

3 shows an exemplary detection apparatus capable of carrying out the first embodiment of the present invention.

Referring to FIG. 3, an exemplary detection device 30 includes a rate converter 32, a filter 33, a correlator 34, and a memory 35. The detection device 30 may be provided in a device to check whether a specific channel is available or may be configured as a separate device.

The device or detection device 30 first generates a baseband signal or baseband samples 31 using the received signal. Rate converter 32 receives the generated baseband samples 31 to change the sampling rate. Since the sampling rates cannot correlate with one another, the sampling rate of the signal received through the rate converter 32 is changed to correspond to the sampling rate of the receiving device.

The rate converter 32 may optionally be provided when the sampling rate used at the transmitting side of the signal and the sampling rate used at the receiving side device of the signal are different. The rate converter 32 may not be provided when the sampling rate used at the transmitting side of the signal and the sampling rate used at the receiving side device of the signal are the same. In addition, the rate converter 32 may not be provided when the received signal can be changed in other ways so that the receiving device can correlate.

The filter 33 receives the signal with the sampling rate set and removes the signal for the frequency domain which is not necessary for correlation. By controlling the unnecessary signal through the filter 33, a more accurate correlation result can be obtained.

The correlator 34 receives the filtered signal and correlates with preamble information known to the device receiving the signal. Through the correlator 34, it is possible to determine how much the signal received and the preamble information known by the device receiving the signal match each other. Ideally, the correlation will only be detected if the received signal and the preamble information known by the device receiving the signal match each other. However, in the case of non-ideality, some noise-like signals may be detected even when the received signal and the preamble information known by the device receiving the signal coincide with each other.

The memory 35 may store preamble information for identifying a communication system used by the correlator 34. The device uses the preamble information stored in the memory to check whether it matches the received signal. When a plurality of preamble information is stored, all of the stored preamble information may be sequentially or simultaneously correlated, or some of them may be selected to correlate sequentially or simultaneously.

When the correlation value is detected through the correlator 34, the communication system corresponding to the preamble generating the detected correlation value 36 exists and determines that the specific channel is unavailable. If the correlator is not ideal, multiple correlation values may be detected for multiple stored preambles. In this case, it is determined that the specific channel is unavailable because the communication system corresponding to the preamble that has generated the maximum value exists among the plurality of detected correlation values.

A predetermined threshold value may be used to distinguish whether the detected correlation value 36 is a signal indicating that the received signal for any preamble matches or is noise. As described above, only when the detected correlation value exceeds a preset threshold, the received signal for a certain preamble may be regarded as a signal indicating that the received signal matches, and the specific channel may be determined to be unavailable. That is, when the detected correlation value is smaller than the preset threshold, it may be regarded as noise, and it may be determined that the specific channel is available.

4 is a diagram for explaining a second embodiment of the present invention.

An embodiment that can be used when some communication systems transmit only a strong signal is described with reference to FIG. 4.

4A and 4B show that two devices 40 and 41 included in communication system B communicate using a specific channel, and the device 42 included in communication system A uses the specific channel. In this case, it is intended to determine whether the above specific channel is available.

The device 42 included in the communication system A may determine whether the specific channel is available through the channel availability determination method described above. However, in order for the device included in the communication system A to use the above-described method of determining whether to use the channel, it is necessary to receive a signal from one of the two devices 40 and 41 included in the communication system B. Preferably the device included in communication system A will have to receive a preamble representing communication system B from either of the two devices 40, 41 included in communication system B.

However, as shown in FIG. 4A, when the signals transmitted by the two devices 40 and 41 included in the communication system B are highly directional, the device 42 included in the communication system A is the communication system B. The probability of receiving a preamble indicating is greatly reduced.

Therefore, in the present embodiment, as shown in FIG. 4B, a device included in the communication system B that transmits only a signal having a strong directionality transmits a signal corresponding to preamble information periodically for at least one or more directions. . Preferably, a device included in the communication system B that transmits only a strong signal transmits a preamble signal for all directions. For example, when one device 40 included in the communication system B is able to receive the above signal by devices included in the 30 degree region through one signal transmission, the one device 40 included in the communication system B A total of 12 times can transmit the preamble signal in all directions.

The device included in the communication system transmitting only the strong signal as described above periodically transmits the preamble signal to cover the omnidirectional direction. Through this, a device that wants to determine whether a specific channel is available may receive a preamble from a device included in a communication system that transmits only a strong signal. Thus, the device may correlate the preamble received by the method with preamble information known to the device to determine if a particular channel is available.

As described above, when the channel band or the channel bandwidth of the transmitting side and the receiving side are different from each other, it is difficult to correlate the preamble signal transmitted from the transmitting side with the preamble information known from the receiving side, and an accurate result is not obtained. You may not be able to.

In this case, as described above, the receiving side detection apparatus may include a rate converter to adjust the sampling rate of the transmitting side signal to the receiving side sampling rate using the above rate converter. In addition, when sampling the signal received at the receiving side, sampling may be attempted by adjusting the number of sampling itself. Alternatively, the signal received at the receiving side may be sampled according to the receiving side sampling rate, and additional sampled values may be obtained by performing interpolation on the sampled values. Alternatively, the signal received at the receiving side may be sampled according to the receiving side sampling rate, and only sampled values selected by selecting some of the sampled values may be used.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 and 6 when channel bandwidths of a transmitting side and a receiving side (or a detecting side) communication systems are different.

It is a figure for demonstrating 3rd Embodiment of this invention.

5 (a) shows the channel bandwidth 50 for the device of communication system A and the channel bandwidth 51 for the device of communication system B. FIG. In addition, when the channel bandwidth 50 for the device of the communication system A and the channel bandwidth 51 for the device of the communication system B are different from each other, the case in which the device of the communication system A receives a signal from the above channel.

More specifically, the channel frequency bandwidth 51 used by the device of the communication system B of the transmitting side of the preamble signal is used by the receiving device, that is, the device of the communication system A which receives and correlates the preamble signal. The case larger than (50) is shown. If the channel frequency bandwidth 51 of the transmitting device is larger than the channel frequency bandwidth 50 used by the receiving device, the frequency band for the transmitting signal is narrow because the channel frequency bandwidth 50 of the receiving side to be detected is narrow. I can't hear it all.

In other words, the relatively wide frequency band for a device can be seen as a higher sampling rate for the signal. That is, the period in which the preamble signal generated in the transmitting device is sampled is shorter than the period in which the receiving device receives and samples the above signal.

As described above, when the sampling period used in the receiving device is larger, when the sampled signal is the signal 52 of the waveform shown in the upper part of FIG. The waveform cannot be recognized as it is without further execution through a transducer. For example, if the received signal 52 is sampled at the sampling period 53 used in the detecting device as shown in the interruption of Fig. 5 (b), the signal of the waveform shown at the bottom of Fig. 5 (b) ( 54).

Therefore, according to the present embodiment, the device samples or filters the original preamble signal of one communication system from the receiving side (or detecting side) device rather than storing the preambles of the coexisting communication system as they are. The signal of the pattern is stored as preamble information of the communication system. For example, even when the original preamble signal of the communication system is the signal 52 having the waveform at the top of FIG. 5 (b), the waveform of the signal 52 is not stored as the preamble information of the communication system as it is. The signal 54 having the waveform generated after sampling or filtering at the detection side device is stored as preamble information of the communication system.

By configuring the preamble information for the communication system as described above, it is possible to more simply and effectively perform a correlation process for confirming or determining whether to use the channel even between systems having different channel frequency bands or sampling rates.

It is a figure for demonstrating 4th Embodiment of this invention.

6 (a) shows the channel bandwidth 61 for the device of communication system A and the channel bandwidth 60 for the device of communication system B. FIG. In addition, when the channel bandwidth 61 for the device of the communication system A and the channel bandwidth 60 for the device of the communication system B are different from each other, the case in which the device of the communication system A receives a signal from the above channel. That is, when the device receives the signal to check whether a specific channel is available in the device of the communication system A will be the preamble signal of the communication system B.

The case where the channel frequency bandwidth 61 used by the receiving side device is larger than the channel frequency bandwidth 60 used by the transmitting side device is shown. If the channel frequency bandwidth 61 of the receiving device is larger than the channel frequency bandwidth 60 used by the transmitting device, the channel frequency bandwidth 60 of the receiving side to be detected is wider, and therefore, due to noise, Results may be less accurate.

In other words, the relatively wide frequency band for a device can be seen as a higher sampling rate for the signal. That is, the period in which the preamble signal generated in the transmitting device is sampled is longer than the period in which the receiving device receives and samples the above signal. As described above, more frequent sampling at the receiving side may include noise other than necessary information, so accurate preamble reception may be difficult, and thus the accuracy of the correlation value is also reduced.

To this end, an analog filter may be implemented to include a method of filtering a received signal. However, in this case, multiple analog filters may be required for multiple expected channel bandwidths, respectively. Thus, there may be disadvantages in terms of cost and volume.

Therefore, the present embodiment proposes a method of using a digital filter, a digital mixer, and a down sampler when the receiving side channel bandwidth is larger than the transmitting side channel bandwidth. The configuration on the receiving side for this is shown in Figure 6 (b).

Referring to FIG. 6B, the receiving side may include a digital mixer 63, a digital filter 64, and / or a down sampler 65. In this case, the digital mixer 63 receives a signal for a wide band corresponding to the channel side band of the receiving side and converts the center frequency of the received signal. That is, since the channel bandwidths of the signals transmitted from the transmitter and the signals received from the receiver are different, a process of matching the center frequencies of the two signals is necessary.

The digital filter 64 receives the converted signal and converts the center frequency for the wide band into a frequency bandwidth corresponding to the transmission side channel frequency band. For example, in FIG. 6A, since a signal for the channel bandwidth of the communication system B is received and the above signal is received as the channel bandwidth of the communication system A, a filter corresponding to the channel bandwidth of the communication system B for the received signal is received. Use to remove the signal of the unnecessary band. That is, filtering is performed on the received signal using a filter corresponding to the channel bandwidth of the communication system B.

The down sampler 65 performs sampling by lowering the sampling rate rather than performing sampling at the original sampling rate of the receiving side. As described above, when the channel frequency bandwidth is larger, the sampling rate is higher, that is, the sampling period is shorter. Accordingly, the sampling rate may be reduced at the receiving side to generate a signal corresponding to the transmitting channel bandwidth.

Both the digital filter 64 and the down sampler 65 may be provided, but only one of them may be provided if necessary.

Hereinafter, a method of generating preamble information used in correlation using the above configurations 63 to 65 will be described. A device in communication system A that wants to determine if a particular channel is available receives a signal from the above channel. This signal may be a preamble signal for communication system B which is currently available for the channel. The receiving side or the detecting side receiving the preamble signal for the communication system B receives the signal corresponding to the frequency bandwidth of the communication system A. In this case, since the channel bandwidths of the transmitting and receiving sides are different from each other, a process of adjusting them may be performed.

 The received signal 62 corresponding to the frequency bandwidth of the communication system A is converted through the digital mixer 63 to the center frequency of the received signal. The center frequency converted signal is filtered through the digital filter 64 corresponding to the frequency bandwidth of the communication system B. Additionally or alternatively, sampling is optionally performed via down sampler 65. The signal generated through this will be a signal converted corresponding to the frequency bandwidth of communication system B. This converted signal can be preamble information that can be used by the detection side device. In the case of correlation using the signal generated by the above method, more accurate correlation result may be obtained.

Some communication systems may have multiple channels. That is, communication may be performed on at least two channels within a specific channel that are smaller than this specific channel bandwidth.

Hereinafter, a method of detecting all of a plurality of channels included in a specific channel will be described with reference to FIG. 7.

It is a figure for demonstrating 5th Embodiment of this invention.

7 (a) shows the channel bandwidth 71 of the detection side communication system A that receives a signal on a specific channel and the multiple channels of the communication system B that can use some or all of the above specified channel, i.e., transmit the above signal. (70) is shown.

That is, a device in communication system A that wants to determine whether a particular channel is available receives a signal over that particular channel. In this case, a plurality of narrow band channels 70 may be included in the above channel range and at least one of the plurality of narrow band channels 70 may be used in the above channel range due to the characteristics of the communication system B. The device of the communication system B, which is the detection side, may accurately determine whether the specific channel is available when all of the plurality of narrowband channels 70 are detected.

In such a case, exemplary methods for detecting multiple narrowband channels will be described. First, in the first method, the plurality of narrowband channels may be sequentially correlated and detected. As shown in FIG. 7 (a), for example, when the communication system B may include a total of five narrow band channels, the above five narrow band channels are sequentially detected and / or the channel availability decision process is performed one by one. .

In this case, each channel may be detected and / or determined whether to use the channel using a method that may be used when the channel bandwidth of the detecting device described above with reference to FIG. 6 is wider.

As a second method for detecting a plurality of narrow band channels, each of the plurality of narrow band channels may be correlated and detected simultaneously. As such, in order to simultaneously identify a plurality of channels, a detection apparatus must be provided with a number corresponding to the number of the plurality of channels. As described above, when a plurality of detection apparatuses are provided to simultaneously identify channels, the verification time can be shortened compared to the first method.

Even in this case, in order to detect each channel and / or determine whether to use the channel, a method that can be used when the channel bandwidth of the detection device described with reference to FIG. 6 is wider can be used.

As a third method for detecting a plurality of narrow band channels, it is assumed that when each channel is used, that is, when all preamble signals of each channel are received, the preamble pattern is used to perform correlation at this time. Save and use as preamble information. In this case, a preamble pattern may be generated when it is assumed that all preamble signals of each channel are received by configuring a filter that may include a plurality of narrow bands.

Referring to FIG. 7B, a configuration of an exemplary filter 72 that may include a plurality of narrow bands all at the top. The preamble pattern 73 in the case where it is assumed that all preamble signals of each channel generated using the above filter are received at the bottom. The receiving side or detecting side device does not check the plurality of narrowband channels, but uses the preamble pattern 73 as the preamble information when it is assumed that all preamble signals of each channel are received as above. do. In this case, the most accurate correlation result may be obtained when the preamble signal is received from all narrowband channels.

Hereinafter, another embodiment of the present invention will be described.

A device of one communication system receives a signal of a particular channel to determine whether a particular channel is available as described above. The received signal is then correlated with preamble information for a plurality of communication systems stored in the device. If it is determined that the preamble of the specific communication system and the received signal match, the specific channel is determined to be used in the specific communication system.

At this time, when the strength of the received signal is particularly weak or the noise level is increased, such as when the transmitting or receiving device is located at the boundary of the communication cell, the received signal is small or mixed with noise. If the correlation is performed at, the probability of inaccurate results increases.

In this case, when receiving a signal from a specific channel, at least two or more signals are received instead of only one signal. Then, it is checked whether the received signals correspond to the preamble information of a specific communication system through the correlation between the received signals and the preamble information known by the receiving device.

In particular, through this process, two or more signals corresponding to preamble information of a specific communication system are detected. The period between the signals corresponding to the preamble information of the two or more specific communication systems detected above is measured. If the receiving device confirms that the specific communication system exists through the preamble correlation method, the receiving device may further confirm whether the specific communication system exists again using the period of the signals identified above.

That is, the receiving device receives two or more signals to obtain correlation values of the respective signals, and measures the period between the detected signals when two or more signals are detected. In addition, the receiving device may check whether the checked communication system is correct again by comparing period information for identifying the communication system identified through correlation with the measured period. The period information for distinguishing the communication system may be a period for transmitting a preamble signal in the communication system or a period for broadcasting a scheduling message in the communication system.

Hereinafter, another method of determining whether to use a specific channel will be described with reference to FIG. 8.

8 is a diagram for explaining a sixth embodiment of the present invention.

8 illustrates a period in which the scheduling messages 80 and 81 of the specific communication system are transmitted or broadcasted when the scheduling message is used as an example of period information of the specific communication system. 8 shows the result values 82 to 86 of receiving a plurality of signals at the receiving device and correlating the plurality of received signals using preamble information stored in the receiving device.

The receiving device can confirm that the communication system corresponding to the preamble information that generated the correlation values 82 and 85 corresponding to the maximum value among the detected correlation values 82 to 86 exists in the specific channel. have. In addition, two or more correlation values 82 and 85 corresponding to maximum values among the correlation values 82 to 86 detected as described above are present and signals corresponding to the correlation values 82 and 85. If it is confirmed that the period between the communication and the transmission cycle of the scheduling message in the specific communication system identified above, it determines that the communication system exists in the specific channel. That is, it may be determined that the specific channel is not currently available.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. You will know. For example, although the present invention has been described with reference to checking whether a communication system exists in a specific channel, the present invention can be applied when it is necessary to distinguish the communication system in any other situation.

That is, it is to be understood that this patent is not to be limited by the embodiments shown herein but is to be accorded the broadest scope consistent with the principles and features disclosed herein.

According to one embodiment of the present invention as described above, effective communication can be performed. In addition, according to an embodiment of the present invention, when a channel is to be used, it is possible to check whether a system using the channel exists.

Claims (13)

A method for determining whether a particular channel is available when at least one communication system is capable of: Receiving at least one signal on the particular channel; And Determining whether the particular channel is available using the received signal and at least one preamble information corresponding to each of the at least one communication system Including a channel, determining whether to use. The method of claim 1, The determining step, And determining whether the specific channel is available through at least one correlation value generated by correlating the received signal with the at least one preamble information. The method of claim 2, The determining step, And determining that the specific channel is unavailable when the at least one correlation value exceeds a preset threshold. The method of claim 2, The determining step, And determining that the specific channel is available when the at least one or more correlation values do not reach a predetermined threshold. The method of claim 1, When the signal transmitted from the at least one communication system is directional, the at least one communication system, And periodically transmitting a signal corresponding to the preamble information for at least one or more directions. The method of claim 1, The at least one preamble information, And wherein the original preamble signal of the at least one communication system is filtered to correspond to a receiving side channel bandwidth. The method of claim 1, Perform down sampling on the received signal, The determining step, And determining whether the specific channel is available by using the down-sampled signal and the at least one preamble information. The method of claim 1, When receiving a signal from a plurality of channels in the receiving step, The determining step, And determining whether the plurality of channels are available using the signals received from the plurality of channels and the at least one preamble information. The method of claim 1, When receiving a signal from a plurality of channels in the receiving step, The determining step, And simultaneously determining whether the plurality of channels are available using the signals received from the plurality of channels and the at least one preamble information. The method of claim 1, When receiving a signal from a plurality of channels in the receiving step, The at least one preamble information, And a pattern generated in consideration of all the signals received from the plurality of channels. The method of claim 2, And measuring a period between the generated one or more correlation values. The method of claim 11, The determining step, And comparing the measured period with period information of the at least one communication system and determining that the specific channel is unavailable. The method of claim 12, Period information of the at least one communication system, And information on one of a period of broadcasting a scheduling message in the communication system and a period of transmitting a preamble signal in the communication system.

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