JP2015122564A - Communication device, channel estimation method, and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device capable of improving accuracy in channel estimation in MIMO even when a low-speed signal is used.SOLUTION: A communication device for processing a reception signal that may include a transmission signal including a unique word comprises: a signal detection unit for detecting a transmission signal from the reception signal; a signal discrimination unit for discriminating the detected transmission signal by an amount of phase rotation and amplitude change of a unique word included in the detected transmission signal; a first phase correction unit for correcting a phase of the discriminated transmission signal on the basis of phase rotation difference between the amount of phase rotation of the unique word included in the discriminated transmission signal and an amount of reference phase rotation corresponding to the discriminated transmission signal; a second phase correction unit for correcting an error between the transmission signal whose phase is corrected on the basis of phase rotation difference and an initial value of phase; and a channel estimation unit for estimating a channel on the basis of the transmission signal whose phase error is corrected and discriminated and an existing signal.

Description

  The present invention relates to a communication device, a channel estimation method, and a communication system.

  In recent years, spatial sensors using an array antenna or MIMO (Multiple-Input and Multiple-Output) have been developed. Examples of the technology related to the space sensor include the technology described in Patent Literature 1 and the technology described in Patent Literature 2.

  Transmission signals in normal MIMO are transmitted simultaneously from, for example, an antenna on the transmission side (hereinafter referred to as “transmission antenna”). Further, in normal MIMO, a signal modulated by OFDM (Orthogonal Frequency Division Multiplexing) (hereinafter referred to as “OFDM signal”) is used in order to increase the speed and capacity. When MIMO is used, channel estimation is necessary, and in order to improve the accuracy of channel estimation, it is desirable to establish synchronization between the communication device on the transmission side and the communication device on the reception side. In OFDM, for example, a communication device on the transmission side and a communication device on the reception side are synchronized using a short preamble, a pilot signal, a guard interval, or the like.

JP 2008-139077 A JP 2008-216152 A

  In the case of using OFDM, the cost of a device (for example, a transmitter circuit) involved in communication is high, and there may be a limit on the usable frequency band. For example, in a spatial sensor using MIMO, a high-speed signal such as an OFDM signal is not actually required, and a lower-speed signal is sufficient. Therefore, a spatial sensor using MIMO that can use a slower signal without using OFDM is desired.

  However, when a low-speed signal is used in MIMO, the carrier offset (the shift in carrier frequency between the communication device on the transmission side and the communication device on the reception side) becomes equivalently large with respect to the signal transmission rate. It becomes difficult to perform channel estimation.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve the accuracy of channel estimation in MIMO even when a low-speed signal is used. It is an object of the present invention to provide a new and improved communication apparatus, channel estimation method, and communication system.

  In order to solve the above-mentioned problem, according to an aspect of the present invention, a transmission signal including a unique unique word for each transmission antenna, which is transmitted by switching from a plurality of transmission antennas, can be received by a reception antenna. A signal detection unit that detects the transmission signal by detecting a switching section of the transmission signal that is switched and transmitted from the reception signal, and a communication device that processes the reception signal demodulated from the received signal; A signal discriminating unit that discriminates a detected transmission signal based on a phase rotation amount of the unique word included in the detected transmission signal and an amplitude change before and after the section of the unique word, and a unique word included in the discriminated transmission signal The determined transmission based on the phase rotation difference between the phase rotation amount and the reference phase rotation amount corresponding to the determined transmission signal. A first phase correction unit that corrects the phase of the signal, a second phase correction unit that corrects an error between the transmission signal whose phase is corrected based on the phase rotation difference and the initial value of the phase, and the phase error is corrected There is provided a communication apparatus comprising: a channel estimation unit that estimates a channel based on the determined transmission signal and a known signal.

  The signal discriminating unit determines whether the amplitude before and after the section of the unique word is different depending on whether the phase of the unique word included in the detected transmission signal is rotating clockwise or counterclockwise. The transmission signal may be discriminated by being different.

  The signal discriminating unit may discriminate the transmission signal by detecting that the amplitude of the modulation point before and after the unique word section is larger or smaller than the amplitude of the modulation point of the unique word.

  In order to solve the above problem, according to another aspect of the present invention, a transmission signal including a unique unique word for each transmission antenna, which is transmitted by switching from a plurality of transmission antennas, may be included. A communication method for processing a reception signal obtained by demodulating a signal received by an antenna, wherein the transmission signal is detected by detecting a switching section of the transmission signal to be switched and transmitted from the reception signal. Step, a signal determination step for determining the detected transmission signal based on the phase rotation amount of the unique word included in the detected transmission signal and the amplitude change before and after the section of the unique word, and included in the determined transmission signal Based on the phase rotation difference between the phase rotation amount of the unique word and the reference phase rotation amount corresponding to the determined transmission signal, A first phase correction step for correcting the phase of the determined transmission signal; a second phase correction step for correcting an error between the transmission signal whose phase is corrected based on the phase rotation difference and an initial value of the phase; A channel estimation method is provided, comprising: a channel estimation step of estimating a channel based on the determined transmission signal whose phase error is corrected and a known signal.

  In order to solve the above-described problem, according to another aspect of the present invention, a first communication device that transmits a transmission signal including a unique unique word for each transmission antenna by switching from a plurality of transmission antennas; And a second communication device that processes a received signal obtained by demodulating a signal received by a receiving antenna, the first communication device including a plurality of transmitting antennas. And a transmission unit that switches and transmits a transmission signal corresponding to the transmission antenna, and the second communication device detects a switching interval of the transmission signal that is switched and transmitted from the reception signal, A signal detector that detects the transmission signal, a phase rotation amount of the unique word included in the detected transmission signal, and an amplitude change before and after the section of the unique word; A signal discriminating unit for discriminating the detected transmission signal, a phase rotation difference between the phase rotation amount of the unique word included in the discriminated transmission signal and the reference phase rotation amount corresponding to the discriminated transmission signal. And a second phase correction for correcting an error between the transmission signal whose phase is corrected based on the phase rotation difference and the initial value of the phase. And a channel estimation unit for estimating a channel based on the determined transmission signal with the phase error corrected and the known signal, a communication system is provided.

  In order to solve the above problems, according to another aspect of the present invention, a plurality of transmission antennas that switch and transmit a transmission signal including a unique unique word for each transmission antenna, and a transmission corresponding to the transmission antenna A transmission unit that switches and transmits signals, wherein the transmission signal has different amplitudes at the modulation point of the unique word and the modulation points before and after the unique word section. An apparatus is provided.

  As described above, according to the present invention, a new and improved communication apparatus, channel estimation method, and communication capable of improving the accuracy of MIMO channel estimation even when a low-speed signal is used. A system can be provided.

It is explanatory drawing for demonstrating the outline | summary of the channel estimation method which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the data format of the transmission signal which the 1st communication apparatus which concerns on embodiment of this invention transmits. It is explanatory drawing which shows the other example of the data format of the transmission signal which the 1st communication apparatus which concerns on embodiment of this invention transmits. It is a block diagram which shows an example of a structure of the 1st communication apparatus 100 which concerns on embodiment of this invention. It is a block diagram which shows an example of a structure of the 1st communication apparatus 100 which concerns on embodiment of this invention. It is a block diagram which shows an example of a structure of the 2nd communication apparatus 200 which concerns on embodiment of this invention. It is explanatory drawing for demonstrating an example of the process which concerns on the frame synchronization in the 2nd communication apparatus 200 which concerns on embodiment of this invention. It is explanatory drawing which shows the signal point in the case of modulating by 16QAM. It is explanatory drawing which shows the example of the specific signal format which concerns on embodiment of this invention. It is explanatory drawing which shows the signal point in the case of modulating by 64QAM. It is explanatory drawing which shows the signal point in the case of modulating by QPSK. 6 is an explanatory diagram illustrating a selection example of signal points of a signal modulated by 16QAM when the first communication device 100 has four transmission antennas. FIG. It is explanatory drawing which shows the example of the phase change of four unique words. It is explanatory drawing which shows the example of an estimation result of the propagation channel in the 2nd communication apparatus 200 which concerns on embodiment of this invention. It is explanatory drawing which shows the example of the result of having estimated the propagation channel irrespective of embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Overview of Channel Estimation Method According to Embodiment of the Present Invention>
Before describing the configuration of a communication apparatus according to an embodiment of the present invention, an overview of a channel estimation method according to an embodiment of the present invention will be described. In the following, for simplification of description, an outline of the channel estimation method according to the embodiment of the present invention will be described by taking SISO (Single-Input and Single-Output) as an example. The outline of the channel estimation method according to the embodiment of the present invention described below using SISO as an example is essentially the same in MIMO.

  FIG. 1 is an explanatory diagram for explaining an overview of a channel estimation method according to an embodiment of the present invention. In FIG. 1, the communication device on the transmission side is indicated as “Tx”, and the communication device on the reception side is indicated as “Rx”.

  For example, the received signal received by the receiving communication device in FIG. Here, “y (t)” shown in Equation 1 represents a received signal, and “h11” shown in Equation 1 represents a multipath composite wave. Further, “sp (t)” shown in Expression 1 indicates a known signal in the transmission-side communication apparatus and the reception-side communication apparatus, and n (t) in Expression 1 indicates thermal noise. .

  The communication device on the receiving side can estimate the channel, for example, as shown in Equation 2 below, by dividing the received signal by the known signal sp (t). Here, “n (t) / sp (t)” shown in Equation 2 is a noise component and can be ignored.

  However, when the communication apparatus on the receiving side estimates the channel based on, for example, Equation 2, the received signal y (t) is not a modulated signal of a bit string corresponding to the same time t as the known signal sp (t). Correct channel estimation cannot be performed. Therefore, for example, when estimating the channel as shown in Equation 2, it is necessary to perform frame synchronization in the receiving communication apparatus in order to improve the channel estimation system.

  In addition, since the received signal y (t) undergoes frequency rotation as time passes, the receiving side communication device can receive a modulated signal of a bit string corresponding to the same time t (transmitted signal transmitted from the transmitting side communication device). Cannot be extracted from the received signal y (t). Therefore, the communication device on the receiving side needs to perform carrier synchronization when estimating the channel based on Equation 2, for example.

  In addition, since the reception signal y (t) has a sample timing shifted with the passage of time, the reception-side communication device transmits a modulated signal of a bit string corresponding to the same time t (transmission signal transmitted from the transmission-side communication device). Cannot be extracted from the received signal y (t). Therefore, the communication device on the receiving side needs to perform timing synchronization when estimating the channel based on Formula 2, for example.

  Further, when estimating the channel in MIMO as shown in Equation 2, for example, the receiving-side communication apparatus needs to perform frame synchronization, carrier synchronization, and timing synchronization as described with reference to SISO as an example. There is.

  Here, as described above, in OFDM, for example, synchronization is established between a communication device on the transmission side and a communication device on the reception side using a short preamble, a pilot signal, a guard interval, or the like. Therefore, when OFDM is used, frame synchronization, carrier synchronization, and timing synchronization can be achieved, so that it is possible to improve the accuracy of channel estimation in MIMO.

  However, as described above, when OFDM is used, the cost of a device related to communication is high, and there may be a limit on a usable frequency band. For example, when realizing a spatial sensor using MIMO, a high-speed signal such as an OFDM signal is not necessary.

  Therefore, in the channel estimation method according to the embodiment of the present invention, for example, OFDM is not used and a signal slower than the OFDM signal is used. More specifically, in the channel estimation method according to the embodiment of the present invention, the transmission-side communication apparatus (hereinafter, may be referred to as “first communication apparatus”) according to the embodiment of the present invention, for example. A modulated signal modulated by quadrature amplitude modulation (QAM) is transmitted as a transmission signal. Here, examples of the modulation signal based on the quadrature amplitude modulation according to the embodiment of the present invention include 16QAM, 64QAM, and 256QAM. The first communication apparatus according to the embodiment of the present invention transmits a modulated signal modulated by phase shift keying (PSK) as a transmission signal. Here, examples of the modulation signal based on the phase shift keying according to the embodiment of the present invention include QPSK (quadrature phase shift keying) and 8PSK. Needless to say, the modulation scheme of the transmission signal according to the embodiment of the present invention is not limited to the above.

  Further, in the channel estimation method according to the embodiment of the present invention, the communication device on the receiving side according to the embodiment of the present invention (hereinafter may be referred to as “second communication device”) has a unique word (described later). ), A received signal obtained by demodulating a signal received by a receiving antenna is processed, and frame synchronization, carrier synchronization, and timing synchronization are performed to perform channel estimation in MIMO.

  The overview of the channel estimation method according to the embodiment of the present invention has been described above. Then, the process which concerns on the channel estimation method in the 1st communication apparatus which concerns on embodiment of this invention, and a 2nd communication apparatus is demonstrated.

<2. Processing According to Channel Estimation Method According to Embodiment of the Present Invention>
[2-1. Processing in First Communication Device]
First, the process which concerns on the channel estimation method which concerns on embodiment of this invention in the 1st communication apparatus which concerns on embodiment of this invention is demonstrated. In the following, the first communication apparatus according to the embodiment of the present invention mainly includes a case where the first communication apparatus includes two transmission antennas, a first transmission antenna and a second transmission antenna, in the first communication apparatus. Processing related to the channel estimation method according to the embodiment of the present invention will be described. Note that the number of transmission antennas included in the first communication device according to the embodiment of the present invention is not limited to two. For example, the first communication device according to the embodiment of the present invention may include three or more transmission antennas.

  FIG. 2 is an explanatory diagram illustrating an example of a data format of a transmission signal transmitted by the first communication device according to the embodiment of the present invention. The first communication device according to the embodiment of the present invention transmits two transmissions. An example of a transmission signal transmitted when an antenna is provided is shown. “Tx1” illustrated in FIG. 2 is an example of a first transmission signal transmitted from the first transmission antenna (transmission antenna # 1 illustrated in FIG. 2) included in the first communication device according to the embodiment of the present invention. Show. Further, “Tx2” illustrated in FIG. 2 is a second transmission signal transmitted from the second transmission antenna (transmission antenna # 2 illustrated in FIG. 2) included in the first communication device according to the embodiment of the present invention. An example is shown.

  For example, when two transmission antennas are provided, the first communication apparatus according to the embodiment of the present invention transmits the first transmission signal from the first transmission antenna as illustrated in FIG. To transmit the second transmission signal.

  Moreover, the 1st communication apparatus which concerns on embodiment of this invention transmits the transmission signal containing a unique word (UW shown in FIG. 2), for example, as shown in FIG. Here, the unique word according to the embodiment of the present invention is, for example, unique data for each transmission antenna to which a transmission signal is transmitted. In other words, the unique words included in the transmission signal transmitted from each transmission antenna are different from each other.

  More specifically, for example, when two transmission antennas are provided, the first communication device according to the embodiment of the present invention includes a first transmission including a first unique word (UW1 shown in FIG. 2). The signal is transmitted from the first transmission antenna, and the second transmission signal including the second unique word (UW2 shown in FIG. 2) is transmitted from the second transmission antenna.

  The first unique word (UW1 shown in FIG. 2) included in the first transmission signal according to the embodiment of the present invention and the second unique word (shown in FIG. 2) included in the second transmission signal according to the embodiment of the present invention. As UW2), for example, as shown in FIG. 2, data with inverted bits may be used. For example, as shown in FIG. 2, by inverting the bits of the first unique word UW1 and the second unique word UW2, the second communication device according to the embodiment of the present invention uses the unique word to be included in the received signal. The type of transmission signal to be transmitted can be determined.

  Inverted data may be added before and after the unique word according to the embodiment of the present invention. By adding inverted data before and after the unique word according to the embodiment of the present invention, the second communication device according to the embodiment of the present invention can more easily detect the leading symbol of each unique word. Is possible.

  More specifically, for example, as shown in FIG. 2, when inverted data is added before and after each of the first unique word UW1 and the second unique word UW2, the first according to the embodiment of the present invention. The phase rotation amount of one transmission signal and the second transmission signal according to the embodiment of the present invention is inverted. Therefore, for example, by adding inverted data before and after each of the first unique word UW1 and the second unique word UW2, in the second communication device according to the embodiment of the present invention, the first unique word UW1 And the first symbol of each of the second unique words UW2 can be detected more easily.

  In addition, the first communication device according to the embodiment of the present invention has the first unique device so that the second communication device can estimate the start timing and the end timing of the first unique word UW1 and the second unique word UW2 with high accuracy. Bits before and after the word UW1 and the second unique word UW2 are given from signal points having different amplitudes. The second communication apparatus according to the embodiment of the present invention can estimate the start timing and the end timing of the first unique word UW1 and the second unique word UW2 with high accuracy based on changes in phase and amplitude.

  The data format of the transmission signal according to the embodiment of the present invention is not limited to the example shown in FIG.

  For example, the first transmission signal according to the embodiment of the present invention and the second transmission signal according to the embodiment of the present invention do not include the inverted data before and after the first unique word and the second unique word, respectively. May be. Even in the case where inverted data is not added before and after each of the first unique word and the second unique word, the second communication device according to the embodiment of the present invention implements the present invention from the received signal. It is possible to detect the first transmission signal according to the embodiment or the second transmission signal according to the embodiment of the present invention.

  The number of bits of the first unique word according to the embodiment of the present invention and the second unique word according to the embodiment of the present invention is not limited to 32 bits, and before and after the first unique word and the second unique word, respectively. The number of bits of the inverted data added to is not limited to 8 bits.

  In FIG. 2, the data format of a transmission signal transmitted when the first communication apparatus according to the embodiment of the present invention includes two transmission antennas, ie, a first transmission antenna and a second transmission antenna. Although an example was shown, as described above, the number of transmission antennas included in the first communication device according to the embodiment of the present invention is not limited to two. The first communication apparatus according to the embodiment of the present invention can switch and transmit transmission signals from a plurality of arbitrary number of transmission antennas by changing the sequence of unique words.

  FIG. 3 is an explanatory diagram showing another example of the data format of the transmission signal transmitted by the first communication device according to the embodiment of the present invention. The first communication device according to the embodiment of the present invention is 4 An example of the data format of the transmission signal transmitted in the case of providing one transmission antenna is shown. “Tx1” illustrated in FIG. 3 is an example of a first transmission signal transmitted from the first transmission antenna (transmission antenna # 1 illustrated in FIG. 3) included in the first communication device according to the embodiment of the present invention. Show. Also, “Tx2” shown in FIG. 3 is the second transmission signal transmitted from the second transmission antenna (transmission antenna # 2 shown in FIG. 3) included in the first communication device according to the embodiment of the present invention. An example is shown. “Tx3” illustrated in FIG. 3 is a third transmission signal transmitted from the third transmission antenna (transmission antenna # 3 illustrated in FIG. 3) included in the first communication device according to the embodiment of the present invention. An example is shown. “Tx4” illustrated in FIG. 3 is a fourth transmission signal transmitted from the fourth transmission antenna (transmission antenna # 4 illustrated in FIG. 3) included in the first communication device according to the embodiment of the present invention. An example is shown.

  When four transmission antennas are provided, the first communication device according to the embodiment of the present invention, for example, as shown in FIG. 3, the first transmission signal including the first unique word UW1 from the first transmission antenna, the first The second transmission signal including the second unique word UW2 from the second transmission antenna, the third transmission signal including the third unique word UW3 from the third transmission antenna, and the fourth unique word UW4 from the fourth transmission antenna. The 4th transmission signal containing is transmitted. For example, as shown in FIG. 3, the unique words (UW1 to UW4) included in each transmission signal are unique data having different bit strings.

  Note that inverted data may be added before and after the first to fourth unique words UW1 to UW4 shown in FIG. Here, as the inverted data added before and after the first unique word UW1 shown in FIG. 3, for example, a bit string of “0” can be cited. Further, the inverted data added before the second unique word UW2 shown in FIG. 3 includes, for example, a bit string of “0”, and is added after the second unique word UW2 shown in FIG. Examples of the inverted data include a bit string “1”. Further, as the inverted data added before the third unique word UW3 shown in FIG. 3, for example, a bit string of “1” can be cited, which is added after the third unique word UW3 shown in FIG. An example of the inverted data is a bit string of “0”. Further, as the inverted data added before and after the fourth unique word UW4 shown in FIG. 3, for example, a bit string of “1” can be mentioned. The inverted data added to the first to fourth unique words UW1 to UW4 shown in FIG. 3 is not limited to the above. For example, an arbitrary bit string that can more easily detect the first symbol of each unique word can be added to the first to fourth unique words UW1 to UW4 shown in FIG.

  The first communication apparatus according to the embodiment of the present invention switches and transmits a transmission signal including a unique word having a different bit string for each transmission antenna as shown in FIGS. 2 and 3, for example, from a plurality of antennas. In addition, the first communication device according to the embodiment of the present invention uses the signal points having different amplitudes for the bits before and after the unique word so that the second communication device can estimate the start timing and end timing of the unique word with high accuracy. give. As will be described later, the second communication device according to the embodiment of the present invention discriminates the transmission signal based on the difference in the bit string of the unique word and the difference in the amplitude, and determines the transmission antenna to which the transmission signal is transmitted. It is possible to determine. Therefore, the first communication device according to the embodiment of the present invention includes a plurality of arbitrary number of transmission antennas by changing the sequence of unique words, and transmits a transmission signal including a unique word from each transmission antenna by switching. The structure to do can be taken. An example of the phase change of the first to fourth unique words UW1 to UW4 included in the transmission signal transmitted by the first communication device according to the embodiment of the present invention is shown in FIG.

[2-2. Processing in Second Communication Device]
Then, the process which concerns on the channel estimation method which concerns on embodiment of this invention in the 2nd communication apparatus which concerns on embodiment of this invention is demonstrated. In the following, the first transmission signal transmitted from the first communication apparatus provided with the two transmission antennas of the first transmission antenna and the second transmission antenna is transmitted by the second communication apparatus according to the embodiment of the present invention. Or the process which concerns on the channel estimation method which concerns on embodiment of this invention in a 2nd communication apparatus is mainly mentioned as an example mainly when the received signal which may contain a 2nd transmission signal is demonstrated.

  The second communication apparatus according to the embodiment of the present invention detects a transmission signal including a unique word from a reception signal that can include a transmission signal including a unique word, for example, as illustrated in FIGS. To achieve frame synchronization. The second communication apparatus according to the embodiment of the present invention achieves carrier synchronization and timing synchronization by correcting the phase of the transmission signal detected based on the phase rotation amount of the unique word.

  The second communication apparatus according to the embodiment of the present invention can estimate the channel more accurately, for example, based on the same principle as that of Expression 2. In addition, the specific example of the process which concerns on the channel estimation method which concerns on embodiment of this invention in the 2nd communication apparatus which concerns on embodiment of this invention is mentioned later.

  When the channel estimation method according to the embodiment of the present invention is used, the first communication apparatus (transmission-side communication apparatus) according to the embodiment of the present invention and the second communication apparatus according to the embodiment of the present invention The above processing is performed in each (receiving-side communication device).

  Examples of the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention include separate communication devices. When the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention are separate communication devices, the first communication according to the embodiment of the present invention A channel estimation method according to the embodiment of the present invention is realized by a communication system including the apparatus and the second communication device according to the embodiment of the present invention.

  Note that the channel estimation method according to the embodiment of the present invention is not limited to being performed by a communication system. For example, the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention may be one communication device. In other words, the communication device according to the embodiment of the present invention has both the function of the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention. Good.

  Hereinafter, the configuration of the first communication device according to the embodiment of the present invention and the configuration of the second communication device according to the embodiment of the present invention will be described more specifically. In the following description, the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention are mainly examples of the case where they are separate communication devices. Each of the configuration of the first communication device according to the embodiment of the invention and the configuration of the second communication device according to the embodiment of the present invention will be described.

  In the following description, the first communication apparatus according to the embodiment of the present invention is provided with two transmission antennas, ie, a first transmission antenna and a second transmission antenna, as an example. An example of the configuration of the first communication apparatus according to the above will be described. In the following description, the second communication device according to the embodiment of the present invention is transmitted from the first communication device including two transmission antennas, ie, a first transmission antenna and a second transmission antenna. An example of the configuration of the second communication apparatus according to the embodiment of the present invention will be described by taking as an example the case of processing a reception signal that can include a transmission signal or a second transmission signal.

<3. Configuration Example of Communication Device According to Embodiment of Present Invention>
[3-1. Configuration example of first communication apparatus]
Then, the structural example of the 1st communication apparatus which concerns on embodiment of this invention is demonstrated. 4A and 4B are block diagrams illustrating an example of the configuration of the first communication device 100 according to the embodiment of the present invention. Hereinafter, a configuration example of the first communication device 100 according to the embodiment of the present invention will be described.

  The first communication device 100 includes, for example, a first transmission antenna 102A, a second transmission antenna 102B, and a transmission unit 104.

  Although not shown in FIGS. 4A and 4B, the first communication device 100 is configured by, for example, a CPU (Central Processing Unit) or various processing circuits, a ROM (Read Only Memory), a RAM (Random Access). Memory) or the like. For example, the first communication device 100 connects the above-described components by a bus as a data transmission path.

  A control unit (not shown) controls the entire first communication device 100. Further, the control unit may serve as the transmission unit 104, for example. Needless to say, the transmission unit 104 may be configured by a dedicated or general-purpose processing circuit.

  102 A of 1st transmission antennas are the 1st communication antenna with which the 1st communication apparatus 100 is provided, The 1st transmission signal transmitted from the transmission part 104 is transmitted from 102 A of 1st transmission antennas.

  The second transmission antenna 102B is a second communication antenna provided in the first communication device 100, and the second transmission signal transmitted from the transmission unit 104 is transmitted from the second transmission antenna 102B.

  For example, as illustrated in FIG. 2, the transmission unit 104 switches between the first transmission signal and the second transmission signal and transmits the first transmission signal from the first transmission antenna 102 </ b> A and the second transmission antenna 102 </ b> B.

  For example, as illustrated in FIG. 4A, the transmission unit 104 switches the first transmission signal and the second transmission signal by one transmission circuit 106 and transmits the signal from the corresponding transmission antenna. The configuration of the transmission unit 104 is as described above. Not limited. For example, as illustrated in FIG. 4B, the transmission unit 104 includes a first transmission circuit 106A corresponding to the first transmission antenna 102A and a second transmission circuit 106B corresponding to the second transmission antenna 102B. As the transmission circuit 106A and the second transmission circuit 106B cooperate, the first transmission signal and the second transmission signal may be switched from the corresponding transmission antennas and transmitted.

  The first communication device 100 has, for example, the configuration illustrated in FIG. 4A and FIG. 4B, so that the first transmission signal is transmitted from the first transmission antenna 102A and the second transmission is performed, for example, as illustrated in FIG. The second transmission signal is switched and transmitted from the antenna 102B.

  Of course, the configuration of the first communication apparatus according to the embodiment of the present invention is not limited to the configuration shown in FIGS. 4A and 4B.

  For example, the first communication device according to the embodiment of the present invention may include three or more transmission antennas. When three or more transmission antennas are provided, the first communication device according to the embodiment of the present invention (more specifically, for example, the transmission unit included in the first communication device) is, for example, as shown in FIG. By changing the sequence of unique words, the transmission signal including the unique word is switched and transmitted from each transmission antenna.

  Moreover, the 1st communication apparatus which concerns on embodiment of this invention may further be provided with the structure with which the 2nd communication apparatus which concerns on embodiment of this invention mentioned later is provided, for example. When the first communication apparatus according to the embodiment of the present invention further includes a configuration included in the second communication apparatus according to the embodiment of the present invention described later, the first communication apparatus according to the embodiment of the present invention is The functions of both the communication device on the transmission side and the communication device on the reception side are provided.

  For example, as described above, even if the first communication device according to the embodiment of the present invention has the functions of both the transmission-side communication device and the reception-side communication device, the first communication device according to the embodiment of the present invention. The first communication apparatus can estimate the channel in the same manner as the second communication apparatus according to an embodiment of the present invention described later. Therefore, when the first communication device according to the embodiment of the present invention has the functions of both the transmission-side communication device and the reception-side communication device, the first communication device according to the embodiment of the present invention is The accuracy of channel estimation in MIMO can be improved.

[3-2. Configuration example of second communication apparatus]
Subsequently, a configuration example of the second communication device according to the embodiment of the present invention will be described. 4A and 5 are block diagrams illustrating an example of the configuration of the second communication device 200 according to the embodiment of the present invention. Hereinafter, a configuration example of the second communication device 200 according to the embodiment of the present invention will be described.

  The second communication device 200 includes, for example, a first reception antenna 202A, a second reception antenna 202B, a reception unit 204, a signal detection unit 206, a signal determination unit 208, and a first phase correction unit 210. The second phase correction unit 212 and the channel estimation unit 214 are provided.

  Although not shown in FIG. 5, the second communication device 200 may include, for example, a control unit that can be configured by a CPU, various processing circuits, a ROM, a RAM, and the like. For example, the second communication device 200 connects the above-described components by a bus as a data transmission path.

  A control unit (not shown) controls the entire second communication device 200. Further, the control unit (not shown) includes, for example, one or more of the reception unit 204, the signal detection unit 206, the signal determination unit 208, the first phase correction unit 210, the second phase correction unit 212, and the channel estimation unit 214. You may play the role of. Note that each of the receiving unit 204, the signal detecting unit 206, the signal determining unit 208, the first phase correcting unit 210, the second phase correcting unit 212, and the channel estimating unit 214 is a dedicated unit capable of realizing the function of each unit. Needless to say, it may be configured by a general-purpose processing circuit.

  The first reception antenna 202A is a first communication antenna included in the second communication device 200, and receives a signal that can include a transmission signal transmitted from the first communication device 100 according to the embodiment of the present invention. To do. When the first communication device 100 according to the embodiment of the present invention has the configuration shown in FIGS. 4A and 4B, for example, the first reception antenna 202A is, for example, the first transmission antenna 102A as shown in FIG. The first transmission signal transmitted from the second transmission antenna or a signal that can include the second transmission signal from the second transmission antenna 102B is received.

  The second reception antenna 202B is a second communication antenna included in the second communication device 200, and receives a signal that may include a transmission signal transmitted from the first communication device 100 according to the embodiment of the present invention. To do. When the first communication device 100 according to the embodiment of the present invention has the configuration illustrated in FIG. 4A or FIG. 4B, for example, the second reception antenna 202B includes the first transmission antenna 102A as illustrated in FIG. The first transmission signal transmitted from the second transmission antenna or a signal that can include the second transmission signal from the second transmission antenna 102B is received.

  The receiving unit 204 includes a receiving circuit corresponding to each receiving antenna, for example, and demodulates a signal received by each receiving antenna. For example, in the example illustrated in FIG. 5, the reception unit 204 includes a first reception circuit 216A that demodulates a signal received by the first reception antenna 202A and a second reception circuit that demodulates a signal received by the second reception antenna 202B. 216B.

  The signal detection unit 206 serves to perform frame synchronization. More specifically, the signal detection unit 206 detects the transmission signal, for example, by detecting a transmission signal switching section from the reception signal. For example, when the first transmission signal and the second transmission signal as illustrated in FIG. 2 are transmitted from the first communication device 100 according to the embodiment of the present invention, the signal detection unit 206, for example, from the received signal By detecting a switching interval between the first transmission signal and the second transmission signal, either the first transmission signal or the second transmission signal is detected.

  Here, the first communication device 100 according to the embodiment of the present invention switches and transmits each transmission signal, for example, as illustrated in FIGS. 2 and 3. For example, as shown in FIG. 2 and FIG. 3, there is a switching section when switching transmission signals according to the embodiment of the present invention. Note that the switching interval according to the embodiment of the present invention may be, for example, a period provided intentionally by the first communication device according to the embodiment of the present invention, or the first transmission according to the embodiment of the present invention. It may be a period generated when switching between the signal and the second transmission signal according to the embodiment of the present invention.

  Since the switching interval according to the embodiment of the present invention is a period during which a transmission signal is not transmitted from the first communication device according to the embodiment of the present invention, the reception signal processed by the second communication device 200 is only noise. Become. Therefore, the second communication device 200 detects a reception signal including only noise, that is, detects a noise interval in the reception signal, thereby detecting a data interval including the first transmission signal or the second transmission signal from the reception signal. Is detected.

  FIG. 6 is an explanatory diagram for explaining an example of processing related to frame synchronization in the second communication device 200 according to the embodiment of the present invention. Here, FIG. 6 illustrates an example of a reception signal received by the second communication device 200.

  The second communication device 200 detects the maximum value of power within a set time from the received reception signal. Here, examples of the set time include a time corresponding to two symbols.

  Further, the second communication device 200 sets a value obtained by subtracting a set value from the detected maximum value as a threshold value. Here, the value to be subtracted from the detected maximum value is set to be larger than, for example, the power difference value between the first transmission signal and the second transmission signal.

  Then, the second communication device 200 determines a section that is equal to or less than the set threshold (or a section that is smaller than the set threshold; hereinafter the same) as a noise section, and continues to the determined noise section. The section is determined to be a data section that is a section including a transmission signal.

  For example, as described above, the second communication device 200 can specify the frame position by determining the data section including the transmission signal. Therefore, the second communication device 200 detects the transmission signal switching interval from the received signal and detects the transmission signal, whereby the second communication device 200 can achieve frame synchronization.

  The signal discrimination unit 208 discriminates the detected transmission signal based on the phase rotation amount of the unique word included in the detected transmission signal and the amplitude of the signal point of the detected transmission signal. For example, when the first transmission signal and the second transmission signal as shown in FIG. 2 are transmitted from the first communication apparatus according to the embodiment of the present invention, the signal determination unit 208 adds the detected transmission signal to the detected transmission signal. Whether the detected transmission signal is the first transmission signal or the second transmission signal is determined based on the phase rotation amount of the included unique word.

  The first communication device 100 according to the embodiment of the present invention transmits a transmission signal corresponding to a transmission antenna by switching from a different transmission antenna. Therefore, the signal determination unit 208 can determine the transmission antenna to which the transmission signal is transmitted by determining the detected transmission signal. For example, when the first transmission signal and the second transmission signal as shown in FIG. 2 are transmitted from the first communication apparatus according to the embodiment of the present invention, the signal determination unit 208 determines that the detected transmission signal is By determining whether the transmission signal is the first transmission signal or the second transmission signal, the transmission antenna to which the transmission signal is transmitted is the first communication antenna 102A or the second communication antenna 102B. It can be determined whether there is.

  In addition, the signal determination unit 208 determines the detected transmission signal based on the amplitude of the signal point of the detected transmission signal. Although specific processing will be described later, the first communication device 100 according to the embodiment of the present invention provides bits before and after the unique word from signal points having an amplitude different from that of the unique word. The signal discriminating unit 208 can discriminate the period of the unique word with high accuracy by detecting the change in amplitude.

  The first phase correction unit 210 serves to perform carrier synchronization. For example, the first phase correction unit 210 calculates a phase rotation difference between the phase rotation amount of the unique word included in the transmission signal determined by the signal determination unit 208 and the reference phase rotation amount corresponding to the determined transmission signal. To do. Then, the first phase correction unit 210 performs carrier synchronization by correcting the phase of the determined transmission signal based on the calculated phase rotation difference.

The phase of the transmission signal does not change constantly due to the influence of a roll-off filter that filters the signal. Therefore, the first phase correction unit 210 estimates in advance the phase change amount p _d (t) between samples at the time of oversampling from the transmission signal. When the phase offset is calculated by the following formula 3, the first phase correction unit 210 can obtain the corrected signal by the following formula 4. In Equation 3, N _O means the number of oversampling and N _UW means the number of unique words.

  The second phase correction unit 212 serves to perform timing synchronization. The second phase correction unit 212 corrects an error between the transmission signal transmitted from the first phase correction unit 210 and corrected in phase based on the phase rotation difference, and the initial value of the phase.

  A timing error occurs between the phase rotation amount of the unique word after the phase correction and the phase rotation amount of the ideal unique word, and the transmission with the phase corrected based on the phase rotation difference by the timing error. The initial phase of the signal deviates from 0 [degree]. This timing error is, for example, the D / A converter (Digital-to-Analog converter) included in the transmission circuit included in the first communication device according to the embodiment of the present invention and the A / N included in the reception circuit included in the reception unit 204. This is caused by a sampling rate error with a D-converter (Analog-to-Digital converter), an error in transmission signal switching time in the first communication apparatus 100 according to the embodiment of the present invention, and the like.

  Therefore, the second phase correction unit 212 compensates the timing by correcting the error between the transmission signal whose phase is corrected based on the phase rotation difference as described above and the initial value of the phase, and performs timing synchronization. Plan.

  When the timing error is Ts [degree], the second phase correction unit 212 corrects the signal based on the following Equation 5.

  The channel estimation unit 214 includes a transmission signal that has been discriminated in which the phase error has been corrected by the second phase correction unit 212, and a known signal (first communication device and second communication device 200 according to the embodiment of the present invention). Based on the known signal).

  More specifically, the channel estimation unit 214 detects, for example, the head (t = tmax) of the known signal. Then, the channel estimation unit 214 uses the head of the detected known signal to determine the transmission signal whose phase error has been corrected by the second phase correction unit 212 (that is, the first phase correction unit 210 and the second phase). The channel is estimated by performing, for example, the calculation shown in Equation 6 below on the received signal r ″ (t)) whose phase error has been corrected by the correction unit 212.

<3. Operation Example of Communication Device According to Embodiment of Present Invention>
Then, the operation example of the 1st communication apparatus 100 and the 2nd communication apparatus 200 which concern on embodiment of this invention is demonstrated. In the following description, a case where modulation is performed with 16QAM will be described as an example.

  FIG. 7 is an explanatory diagram showing signal points in the case of modulation with 16QAM. In the case of 16QAM modulation, as shown in FIG. 7, there are three (# 1, # 2, # 3) combinations of signal points with the same amplitude that do not pass through the origin and have the same distance from the origin. First communication apparatus 100 according to the embodiment of the present invention, a combination of signal points having the same amplitude is a unique word.

  In the case of 2 × 2 MIMO with two transmitting antennas and two receiving antennas as in the above-described example, the bit corresponding to the signal point having the amplitude # 2 in FIG. 2 unique word UW2. The first unique word UW1 and the second unique word UW2 are identified by assigning bits so as to change the phase of the amplitude # 2 counterclockwise or clockwise.

  Then, the first communication device 100 can estimate the start timing and the end timing of the first unique word UW1 and the second unique word UW2 with high accuracy. Bits before and after the second unique word UW2 are given from amplitude # 1 or # 3 different from amplitude # 2 in FIG. The bits before and after the first unique word UW1 and the second unique word UW2 are given from the amplitude # 1 or # 3 different from the amplitude # 2, so that the second communication device 200 uses the signal determination unit 208. It is possible to estimate the start timing and end timing of the unique word based on the phase rotation amount and amplitude change of the unique word, and to determine from which antenna the transmission signal is transmitted from the unique word.

  FIG. 8 is an explanatory diagram showing an example of a specific signal format according to the embodiment of the present invention. FIG. 8 shows a signal format example of the first unique word UW1 and the second unique word UW2.

  In the example shown in FIG. 8, the first unique word UW1 and the second unique word UW2 are both transmitted from the first communication device 100 with the amplitude # 2. The bits before and after the first unique word UW1 are transmitted from the first communication device 100 with the amplitude # 1 different from the amplitude # 2. Similarly, the bits before and after the second unique word UW2 are transmitted from the first communication device 100 with the amplitude # 3 different from the amplitude # 2.

  In this way, by changing the amplitude of the signal point between the unique word and before and after the unique word, the first communication device 100 allows the second communication device 200 to accurately specify the start timing and end timing of the unique word. Thus, the second communication device 200 can estimate the start timing and end timing of the unique word with high accuracy.

  In the example illustrated in FIG. 8, the bits before and after the first unique word UW1 are transmitted from the first communication device 100 with the amplitude # 1 different from the amplitude # 2, and before and after the second unique word UW2. The bits are transmitted from the first communication apparatus 100 with the amplitude # 3 different from the amplitude # 2, but the present invention is not limited to such an example. The bits before and after the first unique word UW1 and the bits before and after the second unique word UW2 may both be transmitted with the same amplitude (for example, amplitude # 1). However, if the bits before and after the first unique word UW1 and the bits before and after the second unique word UW2 are transmitted with different amplitudes, the second communication device 200 simply starts the unique word start timing by changing the amplitude. And the end timing can be estimated.

  Up to this point, the case where modulation is performed with 16QAM has been described as an example, but the present invention is not limited to such an example. Next, a case where modulation is performed with 64QAM will be described as an example.

  FIG. 9 is an explanatory diagram showing signal points in the case of modulation with 64QAM. In the case of modulation by 64QAM, as shown in FIG. 9, there are nine combinations of signal points having the same amplitude that do not pass through the origin and have the same distance from the origin. FIG. 9 shows three combinations (# 1, # 2, # 3) among them. First communication apparatus 100 according to the embodiment of the present invention, a combination of signal points having the same amplitude is a unique word.

  Also in the case of 64QAM, as in the case of 16QAM, the first communication device 100 causes the second communication device 200 to transmit the unique word by changing the amplitude of the signal point between the unique word and before and after the unique word. The start timing and end timing can be estimated with high accuracy, and the second communication apparatus 200 can estimate the start timing and end timing of the unique word with high accuracy.

  Next, a case where modulation is performed by QPSK will be described as an example. FIG. 10 is an explanatory diagram showing signal points in the case of modulation with QPSK. When modulating with QPSK, there is only one combination of signal points with the same amplitude. In this case, for example, the first unique word UW1 is rotated counterclockwise, the second unique word UW2 is rotated clockwise, and the bits before and after the unique word are half the data of each unique word and reversely rotated. Use what you made.

  When modulating with QPSK, the first communication device 100 causes the second communication device 200 to start and end the unique word by reversing the phase rotation between the unique word and before and after the unique word. The timing can be estimated with high accuracy, and the second communication device 200 can estimate the start timing and end timing of the unique word with high accuracy.

  Up to this point, the case of 2 × 2 MIMO with two transmission antennas and two reception antennas has been illustrated. Next, a case where there are more than two transmission antennas (for example, four antennas) will be described.

  When there are four transmission antennas, it is not always necessary to select signal points with the same amplitude as unique words, and by combining signals that have substantially the same amplitude, the same effect as with two transmission antennas can be obtained. I can do it.

  FIG. 11 is an explanatory diagram illustrating a selection example of signal points of a signal modulated by 16QAM when the first communication apparatus 100 has four transmission antennas. As shown in FIG. 11, the amplitudes # 1, # 2, # 3, and # 4 are determined, and the signals of the respective amplitudes are combined, so that the first communication device 100 can transmit even when there are four transmission antennas. The same effect as when two antennas are used can be obtained.

  When there are four transmission antennas, four unique words are used. Here, for example, by changing the number of symbols between a first unique word given by a bit whose phase changes counterclockwise and a second unique word given by a bit that also changes counterclockwise, The first communication device 100 can make the second communication device 200 more easily detect the unique word.

  FIG. 12 is an explanatory diagram showing an example of the phase change of four unique words. FIG. 12 shows a first unique word UW1 and a second unique word UW2 given by bits whose phase changes counterclockwise, a third unique word UW3 given by a bit whose phase changes clockwise, and An example of the phase change of four unique words UW4 is shown.

  In the example shown in FIG. 12, the first unique word UW1 and the third unique word UW3 are 8 symbols, and the second unique word UW2 and the fourth unique word UW4 are 6 symbols. Yes. Therefore, it is possible to determine first whether it is the first unique word UW1 or the third unique word UW3, the second unique word UW2 or the fourth unique word UW4 based on the difference in the number of symbols. Furthermore, it is possible to uniquely determine which unique word is based on whether the phase is changing clockwise or counterclockwise.

<4. Example of effects>
The example of the effect which concerns on embodiment of this invention is shown. The modulation method is 16QAM, the unique word length is 8 symbols, the folded unique word transmitted at a signal point with an amplitude different from that of the unique word is 4 symbols, and the result of obtaining the propagation channel by 4 times oversampling is shown in FIG. The result without compensation is shown in FIG.

  When there is no compensation, as shown in FIG. 14, it cannot be estimated at a place where the propagation channel is fixed. However, as shown in FIG. 13, the second communication device 200 can estimate the propagation channel at a substantially fixed location by detecting the unique word as described above. Therefore, the second communication apparatus 200 according to the embodiment of the present invention can improve the accuracy of channel estimation in MIMO.

<5. Summary>
As described above, according to the embodiment of the present invention, the first communication device 100 that transmits a signal by changing the amplitude of the signal point between the unique word and before and after the unique word, and the first transmission signal 100 A second communication device 200 is provided that detects a unique word from the transmitted signal by a phase change amount and a signal amplitude change.

  The first communication device 100 transmits a signal by changing the amplitude of the signal point between the unique word and before and after the unique word, thereby increasing the start timing and end timing of the unique word to the second communication device 200. The second communication device 200 can estimate the start timing and end timing of the unique word with high accuracy from the transmission signal transmitted from the first communication device 100, and determine the unique word. It becomes possible to detect.

  Each step in the processing executed by the apparatus in the present specification does not necessarily have to be processed in time series in the order described as a flowchart or a sequence diagram. For example, each step in the processing executed by each device may be processed in an order different from the order described as the flowchart, or may be processed in parallel.

  In addition, functions (e.g., a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) incorporated in the device in this specification have functions equivalent to the configuration of each device described above. ) Can be created. A storage medium storing the computer program can also be provided. Moreover, a series of processes can also be realized by hardware by configuring each functional block shown in the functional block diagram with hardware.

  For example, a program for causing a computer to function as the first communication device (transmission-side communication device) according to the embodiment of the present invention (for example, a program for causing the computer to function as the transmission unit 104 illustrated in FIGS. 4A and 4B). However, by being executed by the computer, switching of transmission of transmission signals corresponding to each of the plurality of transmission antennas is realized.

  Further, for example, a program for causing a computer to function as the second communication apparatus (reception-side communication apparatus) according to the embodiment of the present invention (for example, the signal detection unit 206, the signal determination unit 208, and the first one illustrated in FIG. The program for causing the phase correction unit 210, the second phase correction unit 212, and the channel estimation unit 214 to function) is executed in the computer, so that the accuracy of channel estimation in MIMO can be improved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, the second communication device according to the embodiment of the present invention may be configured not to include the reception antennas 202A and 202B and / or the reception unit 204. Even if the receiving antennas 202A and 202B and / or the receiving unit 204 are not provided, the second communication device according to the embodiment of the present invention is, for example, “external communication corresponding to the receiving antennas 202A and 202B”. According to an embodiment of the present invention for “a received signal based on a signal received from a device according to the above” or “a received signal received from a device related to external communication corresponding to the receiving antennas 202A and 202B and the receiving unit 204”. It is possible to perform processing related to the channel estimation method. Therefore, for example, the second communication apparatus according to the embodiment of the present invention can improve the accuracy of channel estimation in MIMO even when the receiving antennas 202A and 202B and / or the receiving unit 204 are not provided. it can.

  In addition, the second communication device according to the embodiment of the present invention includes, for example, the configuration (for example, the configuration illustrated in FIG. 4A and FIG. 4B or a modification thereof) included in the first communication device according to the embodiment of the present invention described above. And the like. When the second communication apparatus according to the embodiment of the present invention further includes the configuration included in the first communication apparatus according to the embodiment of the present invention described above, the second communication apparatus according to the embodiment of the present invention is The functions of both the communication device on the transmission side and the communication device on the reception side are provided.

  For example, as described above, even if the second communication device according to the embodiment of the present invention has the functions of both the transmission-side communication device and the reception-side communication device, the second communication device according to the embodiment of the present invention. The communication apparatus 2 can estimate the channel in the same manner as the configuration shown in FIG. Therefore, even if the second communication device according to the embodiment of the present invention has the functions of both the transmission-side communication device and the reception-side communication device, the second communication device according to the embodiment of the present invention. For example, the same effects as those of the second communication device 200 shown in FIG. 5 can be obtained.

  As described above, the first communication apparatus (transmission-side communication apparatus) has been described as an embodiment of the present invention. However, the embodiment of the present invention is not limited to this form. The embodiment of the present invention can be applied to, for example, a radio wave sensor or a spatial sensor that uses a propagation channel response change, and various devices including the sensor.

  In addition, the second communication apparatus (reception-side communication apparatus) has been described as an embodiment of the present invention, but the embodiment of the present invention is not limited to this form. The embodiment of the present invention can be applied to, for example, a radio wave sensor or a spatial sensor that uses a propagation channel response change, and various devices including the sensor. The embodiment of the present invention can also be realized as a signal processing IC (Integrated Circuit) that can be incorporated into the above-described sensor or device.

  Further, as described above, in the embodiment of the present invention, for example, the communication system having the first communication device according to the embodiment of the present invention and the second communication device according to the embodiment of the present invention is used. The channel estimation method according to the embodiment may be realized, and both the function of the first communication device according to the embodiment of the present invention and the function of the second communication device according to the embodiment of the present invention are communicated. It is also possible to realize the channel estimation method according to the embodiment of the present invention by one communication device having the function of the device.

  In the above description, the channel estimation method according to the embodiment of the present invention is applied to MIMO. However, the embodiment of the present invention is applied to, for example, MISO (Multi-Input Single-Output). Is also possible.

DESCRIPTION OF SYMBOLS 100 1st communication apparatus 102A, 102B Transmission antenna 104 Transmission part 106 Transmission circuit 106A 1st transmission circuit 106B 2nd transmission circuit 200 2nd communication apparatus 202A, 202B Reception antenna 204 Reception part 206 Signal detection part 208 Signal discrimination | determination part 210 First phase correction unit 212 Second phase correction unit 214 Channel estimation unit 216A First reception circuit 216B Second reception circuit

Claims (6)

A communication apparatus for processing a reception signal obtained by demodulating a signal received by a reception antenna, which can include a transmission signal including a unique unique word for each transmission antenna, which is transmitted by switching from a plurality of transmission antennas. ,
A signal detection unit for detecting the transmission signal by detecting a switching interval of the transmission signal transmitted by switching from the reception signal;
A signal discriminating unit for discriminating the detected transmission signal according to the phase rotation amount of the unique word included in the detected transmission signal and the amplitude change before and after the section of the unique word;
First, the phase of the determined transmission signal is corrected based on the phase rotation difference between the phase rotation amount of the unique word included in the determined transmission signal and the reference phase rotation amount corresponding to the determined transmission signal. One phase correction unit;
A second phase correction unit that corrects an error between a transmission signal whose phase is corrected based on the phase rotation difference and an initial value of the phase;
A channel estimation unit for estimating a channel based on the determined transmission signal with the phase error corrected and a known signal;
A communication apparatus comprising:   The signal discriminating unit determines whether the amplitude before and after the section of the unique word is different depending on whether the phase of the unique word included in the detected transmission signal is rotating clockwise or counterclockwise. The communication apparatus according to claim 1, wherein the transmission signal is determined by being different.   The signal discriminating unit discriminates a transmission signal by detecting that the amplitude of the modulation point before and after the unique word section is larger or smaller than the amplitude of the modulation point of the unique word. Item 4. The communication device according to Item 1. A communication method for processing a received signal obtained by demodulating a signal received by a receiving antenna, which can include a transmission signal including a unique unique word for each transmitting antenna, which is transmitted by switching from a plurality of transmitting antennas. ,
A signal detection step of detecting the transmission signal by detecting a switching section of the transmission signal transmitted by switching from the reception signal;
A signal discrimination step for discriminating the detected transmission signal according to the phase rotation amount of the unique word included in the detected transmission signal and the amplitude change before and after the section of the unique word;
First, the phase of the determined transmission signal is corrected based on the phase rotation difference between the phase rotation amount of the unique word included in the determined transmission signal and the reference phase rotation amount corresponding to the determined transmission signal. One phase correction step;
A second phase correction step for correcting an error between a transmission signal whose phase is corrected based on the phase rotation difference and an initial value of the phase;
A channel estimation step for estimating a channel based on the determined transmission signal with the phase error corrected and a known signal;
A channel estimation method comprising: A first communication device that transmits a transmission signal including a unique unique word for each transmission antenna by switching from a plurality of transmission antennas;
A second communication device for processing a received signal obtained by demodulating a signal received by a receiving antenna, which may include the transmission signal;
A communication system comprising:
The first communication device is:
Multiple transmit antennas,
A transmission unit that switches and transmits a transmission signal corresponding to the transmission antenna;
With
The second communication device is
A signal detection unit for detecting the transmission signal by detecting a switching interval of the transmission signal transmitted by switching from the reception signal;
A signal discriminating unit for discriminating the detected transmission signal according to the phase rotation amount of the unique word included in the detected transmission signal and the amplitude change before and after the section of the unique word;
First, the phase of the determined transmission signal is corrected based on the phase rotation difference between the phase rotation amount of the unique word included in the determined transmission signal and the reference phase rotation amount corresponding to the determined transmission signal. One phase correction unit;
A second phase correction unit that corrects an error between a transmission signal whose phase is corrected based on the phase rotation difference and an initial value of the phase;
A channel estimation unit for estimating a channel based on the determined transmission signal with the phase error corrected and a known signal;
A communication system comprising: A plurality of transmission antennas that switch and transmit a transmission signal including a unique unique word for each transmission antenna;
A transmission unit that switches and transmits a transmission signal corresponding to the transmission antenna;
With
The communication apparatus is characterized in that the amplitude of the transmission signal differs between the modulation point of the unique word and the modulation point before and after the unique word section.