Source: http://www.google.com/patents/US8180392?dq=6,370,566
Timestamp: 2017-12-11 02:22:13
Document Index: 181498292

Matched Legal Cases: ['§120', '§119', 'Application No. 2007', 'art 215', 'art 215', 'art 215', 'art 215', 'art 215', 'art 215', 'Application No. 2010']

Patent US8180392 - Wireless communication device and signal detection circuit - Google Patents
A wireless communication device that includes a wireless communication unit that performs a wireless communication in a first mode using a first frequency band serving as a first communication channel, and performs the wireless communication in a second mode using a second frequency band including the...http://www.google.com/patents/US8180392?utm_source=gb-gplus-sharePatent US8180392 - Wireless communication device and signal detection circuit
Publication number US8180392 B2
Application number US 13/178,253
Also published as US7986966, US20090061780, US20110267958
Publication number 13178253, 178253, US 8180392 B2, US 8180392B2, US-B2-8180392, US8180392 B2, US8180392B2
Patent Citations (26), Non-Patent Citations (2), Referenced by (11), Classifications (19), Legal Events (1)
US 8180392 B2
A wireless communication device that includes a wireless communication unit that performs a wireless communication in a first mode using a first frequency band serving as a first communication channel, and performs the wireless communication in a second mode using a second frequency band including the first communication channel and a second communication channel that is adjacent to the first communication channel. Also included is a detection unit that monitors each of the first frequency band and the second frequency band, outputs a first detection signal when an interference signal is detected in the first frequency band and outputs a second detection signal when the interference signal is detected in the second frequency band. Further included is a determination unit that determines whether the interference signal is in the first communication channel or in the second communication channel based on the first and second detection signals.
output a second detection signal when the interference signal is detected in the second frequency band; and
a determination unit that determines whether the interference signal is in the first communication channel or in the second communication channel based on the first detection signal and the second detection signal, wherein the determination unit determines that the interference signal is in the second communication channel when the first detection signal is not output and the second detection signal is output from the detection unit.
This application is a continuation Application of, and claims the benefit of priority under 35 U.S.C. §120 from, U.S. application Ser. No. 12/196,564, filed Aug. 22, 2008, now U.S. Pat. No. 7,986,966, which claims the benefit of priority under 35 U.S.C. §119 from Japanese Patent Application No. 2007-216033 filed on Aug. 22, 2007. The entire contents of each of the above applications are incorporated herein by reference.
According to a first aspect of the invention, there is provided a wireless communication device including: a wireless communication unit that is configured to: perform a wireless communication in a first mode using a first frequency band serving as a first communication channel; and perform the wireless communication in a second mode using a second frequency band including the first communication channel and a second communication channel that is adjacent to the first communication channel; a detection unit that is configured to: monitor each of the first frequency band and the second frequency band; output a first detection signal when an interference signal is detected in the first frequency band; and output a second is detection signal when the interference signal is detected in the second frequency band; and a determination unit that determines whether the interference signal is in the first communication channel or in the second communication channel based on the first detection signal and the second detection signal.
In the first embodiment, frequencies of 5.25 GHz to 5.35 GHz and 5.47 GHz to 5.725 GHz shown in FIG. 5 are available, and the channel information storage unit 210 obtains channel information from the frequency ranges. As an example, a bandwidth of each communication channel is 20 MHz as described with reference to FIG. 2. Therefore, available communication channels from a band between 5.25 GHz and 5.35 GHz are five. That is, each of a band of 5.25 ˜5.27 GHz, a band of 5.27˜5.29 GHz, . . . , and a band of 5.33˜5.35 GHz becomes a communication channel. Available communication channels from a band between 5.47 GHz and 5.725 GHz are twelve. That is, each of a band of 5.47 ˜5.49 GHz, a band of 5.49˜5.51GHz, . . . , and a band of 5.69 ˜5.71 GHz becomes a communication channel. Thus, upon communication using the first frequency band, communication in the 20 MHz bandwidth is performed using any one of the above communication channels as the first communication channel (see FIG. 2). On the other hand, upon communication using the second frequency band, communication in the 40 MHz bandwidth is performed using two adjacent communication channels described above. In this case, of two communication channels, the communication channel at a low frequency side becomes the first communication channel and the communication channel at a high frequency side becomes the second communication channel. The channel information storage unit 210 stores information relating to each of the communication channels of the 20 MHz bandwidth as information of CH-a to CH-o.
The frequency switching unit 209 controls the radio unit 202 and the communication data processor 204 using the information CH-a to CH -o. The frequency switching unit 209 may select communication channels at random or first select them from communication channels at a high frequency side, when a communication channel is changed. Upon numbering the respective communication channels as the first, second, and third channels, an even number channel or an odd number channel among them may be selected. Communication channels may be properly selected using a selection technique such as a specific algorithm or the like.
For example, as shown in FIG. 6, it is assumed that, the channel (CH-a) with the band of 5.25˜5.27 GHz is the first communication channel and the channel (CH-b) with the band of 5.27˜5.29 GHz is the second communication channel, and communication in the 40 MHz band has been performed in such a state. The meaning of (first detection signal, second detection signal)=(0, 1) is detection of radar in the second communication channel with the band of 5.27˜5.29 GHz. Therefore, in this case, the communication may be changed into a communication using only the first communication channel with the band of 5.25 ˜5.27 GHz (20 MHz bandwidth communication), or the second communication channel may be changed into another band to continue performing the 40 MHz bandwidth communication. When continuing the 40 MHz bandwidth communication, the band used as the second communication channel should be changed to the band other than the original band of 5.25 ˜5.29 GHz, for example, to a band of 5.29˜5.33 GHz. In this case, a communication channel with the band of 5.29 ˜5.31 GHz is used as the first communication channel and a communication channel with the band of 5.31˜5.33 GHz is used as the second communication channel.
When determined by the radar detection determining unit 208 to switch the communication channel to another band (S5, YES), the radar detection determining unit 208 notifies the determination result to the radio unit 202 and the communication data processor 204. For example, when a band of 5.29˜5.33 GHz is in use, the information CH-c and CH-d is read out from the channel information storage unit 210 and the radio unit 202 is set based on the information. Accordingly, the wireless communication device resumes communication in the 40 MHz bandwidth using the communication channel of a band different from the previously used band (S6).
The filter 203 f is configured to pass through a signal having the 20 MHz bandwidth or the 40 MHz bandwidth among digital signals sent from the ADC 203 a in response to a command from the radar detecting unit 212. In other words, the filter 203 f is a filter in which a band to be passed is variable. The digital signals passing through the filter 203 f are sent to the demodulator 203 e and the radar detecting unit 212. When the wireless communication device 200 performs wireless communication using the first frequency band (20 MHz bandwidth) , the filter 203 f passes only a signal with the 20 MHz bandwidth. On the other hand, when the wireless communication device 200 performs wireless communication using the second frequency band (40 MHz bandwidth) , the filter 203 f passes a signal with the 20 MHz bandwidth or a signal with the 40 MHz bandwidth.
If the radar detecting unit 212 detects the radar (S36, YES), the radar detection determining unit 208 instructs the communication data processor 204 to suspend the transmission of data (S37). The radar detection determining unit 208 detects the presence of radar in the first communication channel (S38) and performs switching to a different communication channel (S39). When it is determined that no radar is detected in step S36 (S36, NO), the wireless communication continues (S35).
When the radar is detected in the second channel mode (step S42, YES) , the radar detecting unit 212 outputs the first detection signal again. Upon receipt of its result, the radar detection determining unit 208 determines that the radar is present in both the first and second communication channels (step S43). Thus, the radar detection determining unit 208 is switched to a communication channel different from the first and second communication channels (S44). The process of steps S43 and S44 corresponds to the steps S11 and S12 described in the first embodiment.
The radar detection in step S42 continues until the radar observation time TO1 elapses (S42, NO, S45, NO). When no radar is detected after the time TO1 elapsed (S45, YES) , the radar detecting unit 212 determines that no radar is detected (S46). Upon receipt of its result, the radar detection determining unit 208 determines that the radar is present in the first communication channel only (S47). Thus, the radar detection determining unit 208 switches the communication channel currently in use to another communication channel (S48).
In step S25, when no radar is detected (step S25, NO, step S49, YES) , the radar detecting unit 212 does not output the first detection signal. The radar detecting unit 212 commands the filter 203 f to transit from the first channel mode to the second channel mode (S50). Accordingly, the filter 203 f performs the second channel mode to pass the first frequency band (20 MHz bandwidth) corresponding to the second channel. Thereafter, the radar detecting unit 212 sets the radar observation time TO1 in the timer (step S51) and observes a radar signal (S52).
When the radar is detected in the second channel mode (step S42, YES) , the radar detecting unit 212 outputs the first detection signal again. Upon receipt of its result, the radar detection determining unit 208 determines that the radar is present in the second communication channel only (S53). The radar detection determining unit 208 determines whether or not to switch the communication channel currently in use to a communication channel of another frequency band (S54).
The radar detection in step S52 continues until the radar observation time TO1 elapses (S52, NO, 558, NO). When no radar is detected after the time TO1 elapsed (S58, YES) , the radar detecting unit 212 determines that no radar is detected (S46). This corresponds to a case in which no radar is detected in either the first communication channel or the second communication channel. However, since it is determined that the radar is detected in step S21, the radar detection determining unit 208 determines that the radar is present in the first communication channel and the second communication channel in consideration of such determination (S59). Consequently, the radar detection determining unit 208 determines whether or not to switch the communication channel currently in use to a communication channel of another frequency band (S60).
First, the frequency converting unit 214 a will be described. The oscillation frequency f1 of the oscillation signal generated from the oscillator 216 described in FIG. 15 is ±10 MHz, for example. That is, the frequency converting unit 214 a shifts the frequency of the digital signal from the ADC 203 a to a plus direction by 10 MHz and shifts it to a minus direction by 10 MHz. The oscillation signal is sampled by a sampling frequency, for example, f2=40 MHz, in the oscillator 216. The oscillation signal sampled by the f2 is sent to the complex multiplier 217. Additionally, in a relation between the oscillation frequency f1 and the sampling frequency f2, a ratio of absolute values of both may be one over power exponentiation of 2, that is, |f1|/|f2|=½n (where n is a natural number). With this, only values of “0”, “1”, and “−1” of sine wave representing the imaginary part 215 d of the oscillation signal is generated from the oscillator 216. This is shown in FIG. 16. FIG. 16 shows waveforms of the imaginary part 215 d of the oscillation signal. As shown, the frequency of the sine wave is 10 MHz, and, as a result of the sampling frequency of 40 MHz, four values per one period (“0”, “1”, “0”, and “−1”) is generated from the oscillator 216.
The real part 215 a and the imaginary part 215 b of the digital signal are multiplied by the real part 215 c and the imaginary part 215 d of the oscillation signal in the complex multiplier 217. As a result, the frequency of the digital signal is shifted by ±10 MHz. The frequency conversion will be described by referring to FIG. 17A-19C. FIG. 17A is a graph showing a frequency distribution of the digital signal, and FIG. 17B is a graph showing a frequency spectrum of the oscillation frequency of the oscillation signal. FIGS. 18A and 19A are graphs showing a frequency distribution of the digital signal, wherein FIGS. 18B and FIG. 19B are graphs showing a frequency spectrum of the oscillation frequency of the oscillation signal, and wherein FIGS. 18C and 19C are graphs showing a frequency distribution of a multiplication result in the complex multiplier 217. Although FIGS. 17A to 19A show the bandwidth of the digital signal as 40 MHz, this is for simplicity of explanation. Thus, digital signals with bands of more than 40 MHz is possible, which is typical.
As a result of step S70, when the pulse determining unit 214 d determines that no radar is present (S71, NO), the communication continues (S72). On the other hand, as a result of step S70, when the pulse determining unit 214 d determines that the radar is present (S71, YES) , the signal level measuring unit 214 c receives the digital signal sent from the band-limiting filter 214 b (S73) . The signal level measuring unit 214 c detects the radar in the first communication channel with respect to the digital signal send from the band-limiting filter 214 b.
If radar is present in at least one communication channel, that is, if radar is determined to be present at least one of the steps S77 and S83 (S84, YES), the radar detection determining unit 207 instructs the communication data processor to suspend the transmission of data (S85). Thereafter, step S3 described in the first embodiment is performed. In this embodiment, the first detection signal =“1” in step S3 corresponds to a case in which radar is determined to be present in the first communication channel (step S77). The second detection signal=“1” corresponds to a case in which radar is determined to be present in the second communication channel (S83).
In the fourth embodiment, the relation of the oscillation frequency f1 and the sampling frequency f2 of s the oscillation signal in the oscillator 216 is designed to satisfy |f1|/|f2|=½n. For example, f1=±10 MHz, and f2=40 MHz. As a result, values of the sampling points in the imaginary part of the oscillation signal are simplified into “0”, “+1”, and “−1”.
As described above, since the relation between the oscillation frequency f1 and the sampling frequency f2 only has to be one overpower exponentiation of two, for example, For example, f1 may be ±20 MHz, and f2 may be 40 MHz. In this case, a value in the sampling point is only “0”.
In addition, as described in the above advantage (5), the radar detecting unit 214 can be reduced in a size by detecting radar from the digital signal. That is, upon use of the analog signal, an operation becomes complicated when the radio signal is divided into a positive frequency component and a negative frequency component, and an operator for complex number must be necessary. For this reason, a circuit size becomes larger. However, in this embodiment, since the central frequency is varied by using the digital signal, the band-limiting filter 214 b adopts only a static digital filter to simplify a circuital configuration.
Although the first frequency bandwidth is defined as 20 MHz and the second frequency bandwidth is defined as 40MHz in the first to sixth embodiments, the bandwidths are not limited thereto. That is, the first frequency bandwidth and the second frequency bandwidth may respectively set to 20 MHz and 80MHz, or may respectively set to 40 MHz and 80 MHz.
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JP2006081149A Title not available
1 Adrian Stephens, et al. "Joint Proposal: High throughput extension to the 802.11 Standard: Mac"; Document Submission: IEEE 802.11-05/1095r5; Jan. 2006; 104 pages.
2 Office Action issued Oct. 4, 2011, in Japanese Patent Application No. 2010-049719 with English translation.
U.S. Classification 455/552.1, 370/479, 455/67.13, 455/67.11, 455/450, 370/337, 455/114.2, 342/57, 370/329, 455/509, 455/63.1, 342/20, 370/342, 342/52, 342/159
Cooperative Classification H04W16/14, G01S7/021