wireless communication device

Abstract

To provide a technique that can suppress an increase in the scale of a receiving circuit.SOLUTION: A wireless communication device includes: a receiving circuit of one system that can switch a standby frequency; and a control unit that switches the standby frequency in the receiving circuit with a period shorter than half of at least any one of first symbol length related to a first symbol rate of a first pilot signal and second symbol length related to a second symbol rate of a second pilot signal whose center frequency is different from that of the first pilot signal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to wireless communication devices. [Background technology]

[0002] For example, in a communication system that supports modulation methods using multiple frequency bandwidths, such as a wireless LAN (Local Area Network), adaptive modulation is achieved by including information for identifying the modulation method in the header of a packet. In this communication system, if the frequency bandwidth differs, the center frequency differs, so the header cannot be detected.

[0003] In recent years, it has been proposed to equip each device that makes up a network with multiple receiving circuits capable of receiving multiple radio signals with different center frequencies so that the header portion can be detected even in multiple frequency bandwidths (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5963574 Summary of the Invention [Problem to be solved by the invention]

[0005] However, providing multiple receiver circuits capable of receiving multiple radio signals with different center frequencies increases the overall size of the receiver circuit.

[0006] Therefore, the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can suppress an increase in the size of a receiving circuit. [Means for solving the problem]

[0007] A wireless communication device according to the present disclosure includes a receiving circuit of one system capable of switching standby frequencies, and a period shorter than half of at least one of a first symbol length related to a first symbol rate of a first pilot signal and a second symbol length related to a second symbol rate of a second pilot signal having a center frequency different from that of the first pilot signal, A frequency for receiving the first pilot signal and a frequency for receiving the second pilot signal, The standby frequency in the receiving circuit as and a control unit for switching. [Effects of the Invention]

[0008] According to the present disclosure, the standby frequency in the receiving circuit is switched at a cycle shorter than half of at least one of a first symbol length related to a first symbol rate of a first pilot signal and a second symbol length related to a second symbol rate of a second pilot signal having a center frequency different from that of the first pilot signal. With this configuration, it is possible to suppress an increase in the size of the receiving circuit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a communication system including a wireless communication device according to a first embodiment. [Figure 2] 1 is a block diagram showing a configuration of a wireless communication device according to a first embodiment. [Figure 3] 4 is a timing chart showing the operation of the wireless communication device according to the first embodiment. [Figure 4] 4 is a timing chart showing the operation of the wireless communication device according to the first embodiment. [Figure 5] 5 is a flowchart showing the operation of the wireless communication device according to the first embodiment. [Figure 6] 10 is a timing chart showing the operation of the wireless communication device according to the second embodiment. [Figure 7] 10 is a timing chart showing the operation of the wireless communication device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <First Embodiment> 1 is a diagram showing the configuration of a communication system including a wireless communication device according to the first embodiment. Wireless communication device 11 is a terminal that transmits and receives signals to and from wireless communication device 13 using signals of frequency bandwidth A (BW-A). Wireless communication device 12 is a terminal that transmits and receives signals to and from wireless communication device 13 using signals of frequency bandwidth B (BW-B). Wireless communication device 13 is a terminal that can receive signals of frequency bandwidth A and signals of frequency bandwidth B. The signals of frequency bandwidth A and frequency bandwidth B include pilot signals, signals of header portions, etc.

[0011] Wireless communication device 11 only needs to communicate with wireless communication device 13 using signals of frequency bandwidth A, and may or may not be able to communicate using signals of frequency bandwidth B. Wireless communication device 12 only needs to communicate with wireless communication device 13 using signals of frequency bandwidth B, and may or may not be able to communicate using signals of frequency bandwidth A.

[0012] For example, in communications in the 920 MHz band, frequency bandwidth A may be 200 kHz (one unit channel), and frequency bandwidth B may be 400 kHz (two unit channels). The signals of frequency bandwidth A and frequency bandwidth B use different unit channels, and therefore have different center frequencies.

[0013] 2 is a block diagram showing the configuration of wireless communication device 13 according to Embodiment 1. Wireless communication device 13 includes filter 21, LNA (Low Noise Amplifier) ​​22, mixer 23, control unit 24, and demodulation unit 25.

[0014] The filter 21 outputs a signal of a predetermined frequency bandwidth from the signals received by the antenna to the LNA 22. The LNA 22 amplifies the signal from the filter 21 without significantly reducing the signal-to-noise ratio. The mixer 23 extracts an in-phase (I-phase) component and a quadrature phase (Q-phase) component by multiplying the signal amplified by the LNA 22 by a signal having a local frequency. The demodulation unit 25 performs demodulation processing based on the I-phase component and Q-phase component extracted by the mixer 23. The mixer 23 corresponds to a single receiving circuit capable of switching standby frequencies.

[0015] The control unit 24 outputs a control signal to the mixer 23 to periodically switch the local frequency of the mixer 23, i.e., the one receiving circuit, thereby periodically switching the standby frequency of the one receiving circuit. This enables the wireless communication device 13 to receive pilot signals with different center frequencies from the wireless communication devices 11 and 12 in a time-division manner.

[0016] The channel used between wireless communication device 11 and wireless communication device 13 is designated to be common to both, and the channel used between wireless communication device 12 and wireless communication device 13 is designated to be common to both. Various techniques, including conventional techniques, can be applied to the method of specifying the channel.

[0017] <Operation> In the following description, the symbol rate of the pilot signal in frequency bandwidth A is assumed to be the first symbol rate of the first pilot signal, and the symbol rate of the pilot signal in frequency bandwidth B is assumed to be the second symbol rate of the second pilot signal. Here, the symbol rate is the number of symbols transmitted per second. The faster the symbol rate, the greater the number of symbols transmitted per second, and therefore the shorter the symbol length required to transmit a certain number of symbols. Therefore, there is a relationship between the symbol rate and the symbol length in that the faster the symbol rate, the shorter the symbol length tends to be.

[0018] In the first embodiment, the first symbol rate of the first pilot signal in frequency bandwidth A is the same as the second symbol rate of the second pilot signal in frequency bandwidth B. The first symbol length related to the first symbol rate of the first pilot signal in frequency bandwidth A is the same as the second symbol length related to the second symbol rate of the second pilot signal in frequency bandwidth B.

[0019] 3 and 4 are timing charts showing the operation of radio communication device 13 according to the present embodiment 1. First, with reference to Fig. 3, the operation of radio communication device 13 according to the present embodiment 1 when receiving a first pilot signal transmitted from radio communication device 11 in frequency bandwidth A will be described.

[0020] At timing 301, the control unit 24 alternately switches the local frequency of the mixer 23 at a period shorter than half the first symbol length related to the first symbol rate of the first pilot signal of frequency bandwidth A, thereby alternately switching the standby frequency in the receiving circuit.

[0021] As described above, in the first embodiment, the first symbol length related to the first symbol rate of the first pilot signal of frequency bandwidth A and the second symbol length related to the second symbol rate of the second pilot signal of frequency bandwidth B are the same. Therefore, the control unit 24 may alternately switch the local frequency of the mixer 23 at a period shorter than half the second symbol length related to the second symbol rate of the second pilot signal of frequency bandwidth B, thereby alternately switching the standby frequency of the receiving circuit. In other words, the control unit 24 alternately switches the standby frequency of the receiving circuit at a period shorter than half of at least either the first symbol length or the second symbol length.

[0022] 3, at timing 301, demodulation processing is performed at each of the center frequency used in frequency bandwidth A and the center frequency used in frequency bandwidth B. As a result, wireless communication device 13 can receive and process the first pilot signal of frequency bandwidth A in the first half of timing 301, but cannot receive and process the first pilot signal of frequency bandwidth A in the second half of timing 301.

[0023] The control unit 24 also performs the same switching as above at each of timings 302, 303, and 304 when the first pilot signal is transmitted from the wireless communication device 11. If the first pilot signal has been received a certain number of times or more, demodulation processing is performed at the center frequency used in frequency bandwidth A at timing 305 when the header portion signal is transmitted from the wireless communication device 11.

[0024] Next, with reference to FIG. 4, an operation of radio communication device 13 according to the first embodiment when receiving a second pilot signal transmitted in frequency bandwidth B from radio communication device 12 will be described.

[0025] At timing 401, the control unit 24 alternately switches the local frequency of the mixer 23 at a cycle shorter than half of at least one of the first symbol length and the second symbol length, thereby alternately switching the standby frequency in the receiving circuit.

[0026] 4, at timing 401, demodulation processing is performed at each of the center frequency used in frequency bandwidth A and the center frequency used in frequency bandwidth B. As a result, wireless communication device 13 is able to receive and process the second pilot signal of frequency bandwidth B in the latter half of timing 401, but is not able to receive and process the second pilot signal of frequency bandwidth B in the first half of timing 401.

[0027] The control unit 24 also performs the same switching as above at each of timings 402, 403, and 404 when a second pilot signal is transmitted from the wireless communication device 12. If the second pilot signal has been received a certain number of times or more, demodulation processing is performed at the center frequency used in frequency bandwidth B at timing 405 when a header portion signal is transmitted from the wireless communication device 11.

[0028] 5 is a flowchart showing an operation of determining a center frequency for performing demodulation processing by wireless communication device 13 according to the present embodiment 1. The operation of FIG. 5 is performed, for example, when a command to determine a frequency bandwidth is issued.

[0029] In step S1, the control unit 24 checks whether the results of demodulation processing at the center frequency used in frequency bandwidth A at timings 301, 302, 303, 304, 401, 402, 403, 404, etc. match a specified pilot pattern. If it is determined that the results match the pilot pattern, the process proceeds to step S2, and if it is determined that the results do not match the pilot pattern, the process proceeds to step S3.

[0030] In step S2, the control unit 24 determines to perform demodulation processing by setting the center frequency of the demodulatable signal to the center frequency of the frequency bandwidth A at timings 305, 405, etc. Then, the operation in FIG.

[0031] In step S3, the control unit 24 checks whether the results of demodulation processing at the center frequency used in frequency bandwidth B at timings 301, 302, 303, 304, 401, 402, 403, 404, etc. match a specified pilot pattern. If it is determined that the results match the pilot pattern, the process proceeds to step S4, and if it is determined that the results do not match the pilot pattern, the process proceeds to step S5.

[0032] In step S4, the control unit 24 determines to perform demodulation processing by setting the center frequency of the demodulatable signal to the center frequency of the frequency bandwidth B at timings 305, 405, etc. Then, the operation in FIG. 5 ends.

[0033] In step S5, the control unit 24 determines not to perform demodulation processing, and then the operation of FIG.

[0034] <Summary of the First Embodiment> According to the wireless communication device 13 of the first embodiment described above, the standby frequency in the receiving circuit is switched at a cycle shorter than half of at least one of the first symbol length and the second symbol length. The first symbol length related to the first symbol rate of the first pilot signal of frequency bandwidth A and the second symbol length related to the second symbol rate of the second pilot signal of frequency bandwidth B are the same.

[0035] This configuration allows a single receiving circuit to receive multiple signals with different center frequencies, which prevents the size of the receiving circuit of wireless communication device 13 from increasing in size in a network where signals with multiple bandwidths coexist within a specific frequency range.

[0036] This is effective in networks where multiple frequency bandwidths and center frequencies coexist, such as M2M networks, as a result of using narrow frequency bandwidth signals for long-distance transmission and wide frequency bandwidth signals for high-speed transmission. For example, in systems such as SUN-OFDM, which have a relatively low symbol rate and allow frequency switching within a symbol, it is possible to configure devices without increasing the circuit scale.

[0037] <Modification> In the first embodiment, four frames of pilot signals are used to determine the center frequency at which demodulation processing should be performed, but the number of frames used for this determination is not limited to four. Also, in the first embodiment, the frame received at the determined center frequency is a frame of the header portion, but depending on the frame format of the signal being handled, a frame of a portion other than the header portion may be used. Also, in Fig. 5, the determination regarding frequency bandwidth A in step S1 is performed before the determination regarding frequency bandwidth B in step S3, but the order of these determinations may be changed as appropriate.

[0038] <Embodiment 2> The block diagram showing the configuration of wireless communication device 13 according to the second embodiment is the same as the block diagram showing the configuration of wireless communication device 13 according to the first embodiment (see FIG. 2). Hereinafter, among the components according to the second embodiment, components that are the same as or similar to the components described above will be assigned the same or similar reference numerals, and different components will be mainly described.

[0039] In the first embodiment, the first symbol rate of the first pilot signal in frequency bandwidth A and the second symbol rate of the second pilot signal in frequency bandwidth B are the same. In contrast, in the second embodiment, the first symbol rate and the second symbol rate are different. The cycle used for switching the standby frequency is shorter than half the symbol length related to the faster of the first and second symbol rates.

[0040] <Operation> In the following description, it is assumed that the first symbol rate of the first pilot signal in frequency bandwidth A is half the second symbol rate of the second pilot signal in frequency bandwidth B, and that the second symbol rate is faster than the first symbol rate. The first symbol length associated with the first symbol rate is also twice the second symbol length associated with the second symbol rate. In the above case, since the second symbol rate is faster than the first symbol rate, the cycle used to switch the standby frequency is shorter than half the second symbol length associated with the second symbol rate of the second pilot signal in frequency bandwidth B.

[0041] 6 and 7 are timing charts showing the operation of radio communication device 13 according to Embodiment 2. First, with reference to Fig. 6, the operation of radio communication device 13 according to Embodiment 2 when receiving a first pilot signal transmitted from radio communication device 11 in frequency bandwidth A will be described.

[0042] At timing 601, the control unit 24 alternately switches the standby frequency in the receiving circuit by alternately switching the local frequency of the mixer 23 in a cycle shorter than half the second symbol length (see FIG. 7) related to the second symbol rate of the second pilot signal of frequency bandwidth B. In other words, the control unit 24 alternately switches the standby frequency in the receiving circuit in a cycle shorter than half of at least either the first symbol length or the second symbol length.

[0043] 6, at timing 601, demodulation processing is performed at each of the center frequency used in frequency bandwidth A and the center frequency used in frequency bandwidth B. As a result, wireless communication device 13 can receive and process the first pilot signal of frequency bandwidth A in the first half of timing 601, but cannot receive and process the first pilot signal of frequency bandwidth A in the second half of timing 601.

[0044] The control unit 24 also performs the same switching as above at each of timings 602, 603, and 604 when a first pilot signal is transmitted from the wireless communication device 11. If the first pilot signal has been received a certain number of times or more, demodulation processing is performed at the center frequency used in frequency bandwidth A at timing 605 when a header portion signal is transmitted from the wireless communication device 11.

[0045] Next, with reference to FIG. 7, an operation of radio communication device 13 according to the second embodiment when receiving a second pilot signal transmitted in frequency bandwidth B from radio communication device 12 will be described.

[0046] At timing 701, the control unit 24 alternately switches the local frequency of the mixer 23 at a period shorter than half the second symbol length related to the second symbol rate of the second pilot signal of frequency bandwidth B, thereby alternately switching the standby frequency in the receiving circuit.

[0047] 7, at timing 701, demodulation processing is performed at each of the center frequency used in frequency bandwidth A and the center frequency used in frequency bandwidth B. As a result, wireless communication device 13 is able to receive and process the second pilot signal of frequency bandwidth B in the latter half of timing 701, but is not able to receive and process the second pilot signal of frequency bandwidth B in the first half of timing 701.

[0048] The control unit 24 also performs the same switching as above at each of timings 702, 703, and 704 when a second pilot signal is transmitted from the wireless communication device 12. If the second pilot signal has been received a certain number of times or more, demodulation processing is performed at the center frequency used in frequency bandwidth B at timing 705 when a header portion signal is transmitted from the wireless communication device 11.

[0049] The flowchart showing the operation of wireless communication device 13 according to the second embodiment to determine the center frequency at which demodulation processing should be performed is the same as the flowchart showing the operation of wireless communication device 13 according to the first embodiment (see FIG. 5).

[0050] <Summary of the second embodiment> According to wireless communication device 13 of the second embodiment as described above, the standby frequency in the receiving circuit is switched in a cycle shorter than half the symbol length related to the faster of the first and second symbol rates. With this configuration, even if the symbol rates of multiple signals to be waited for are different, it is possible to wait with one receiving circuit, thereby suppressing an increase in the size of the receiving circuit of wireless communication device 13.

[0051] <Modification> In the second embodiment, the first symbol rate of the first pilot signal in frequency bandwidth A is half the second symbol rate of the second pilot signal in frequency bandwidth B, but this ratio is not limited to half. Also, for signals with slow symbol rates, the same pilot signal is demodulated multiple times, so it is possible to combine multiple demodulated pilot signals and use them for various purposes. Note that various techniques, including conventional techniques, can be applied to this combining method.

[0052] It should be noted that the embodiments and modifications may be freely combined, and the embodiments and modifications may be modified or omitted as appropriate. [Explanation of symbols]

[0053] 23 mixer, 24 control section.

Claims

1. One receiving circuit that can switch standby frequencies, a control unit that switches, as the standby frequency in the receiving circuit, between a frequency for receiving the first pilot signal and a frequency for receiving the second pilot signal in a cycle shorter than half of at least one of a first symbol length related to a first symbol rate of the first pilot signal and a second symbol length related to a second symbol rate of a second pilot signal having a center frequency different from that of the first pilot signal; A wireless communication device comprising:

2. 2. The wireless communication device according to claim 1, the first symbol rate and the second symbol rate are the same, A wireless communication device, wherein the first symbol length and the second symbol length are the same.

3. 2. The wireless communication device according to claim 1, the first symbol rate and the second symbol rate are different from each other, The wireless communication device, wherein the period is shorter than half a symbol length associated with a faster symbol rate of the first symbol rate and the second symbol rate.

4. 4. The wireless communication device according to claim 1, The control unit A wireless communication device that switches the standby frequency by switching the local frequency of the receiving circuit.

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