WO2020194558A1

WO2020194558A1 - Wireless communication device, communication system, and wireless communication method

Info

Publication number: WO2020194558A1
Application number: PCT/JP2019/013031
Authority: WO
Inventors: 昭範中島
Original assignee: 三菱電機株式会社
Priority date: 2019-03-26
Filing date: 2019-03-26
Publication date: 2020-10-01
Also published as: JPWO2020194558A1; JP6929486B2

Abstract

A mobile station (200) is a wireless communication device that is provided with a plurality of antennas and is capable of transmission processing using delay transmission diversity. The mobile station (200) comprises: a state estimation unit (52) for estimating a mobile state of a wireless communication device on the basis of a transmission path estimation value obtained by a first method and a transmission path estimation value obtained by a second method; and a transmission device (202) for performing, if the mobile state is estimated by the state estimation unit (52) to correspond to a state where a transmission characteristic would deteriorate if delay transmission diversity were performed, processing for stopping use of delay transmission diversity, processing for causing the phase of signals to be transmitted from some antennas of a plurality of antennas to change, or processing for providing a frequency deviation to signals to be transmitted from some antennas.

Description

Wireless communication devices, communication systems and wireless communication methods

The present invention relates to a wireless communication device, a communication system, and a wireless communication method for performing digital wireless communication.

In recent years, in digital wireless communication, in order to improve wireless communication quality, it is generally practiced to acquire transmission / reception diversity gain by using a plurality of transmission / reception antennas to secure a high signal power to noise power ratio.

As a transmission diversity method in which a plurality of antennas are used in a wireless communication device on the transmitting side (hereinafter referred to as a transmitting side), a delayed transmission diversity method in which the same signal is transmitted by making the transmission timing different between the plurality of transmitting antennas. , Circular delay transmission diversity applicable to block transmission such as OFDM (Orthogonal Frequency Division Multiplexing) using guard interval, spatiotemporal block code (STBC: Space Time Block Coding) and time by Alamouti transmission coding. Frequency block codes (SFBC: Space Frequency Block Coding), etc. are known. These are open-loop transmission diversity systems in which the transmitting side does not need to know the state of the transmission path to the receiving side wireless communication device (hereinafter referred to as the receiving side).

The delayed transmission diversity method does not provide the transmission diversity gain for the transmitting antenna, but it enables transmission using the simplest and smallest number of pilot signals. The STBC method and the SFBC method have a drawback that the receiving side needs to estimate all the transmission path states between each transmitting antenna and the receiving antenna, and the insertion loss due to the insertion of the pilot signal is large.

In the transmission diversity method, when the transmitting side knows the transmission line state estimated on the receiving side, precoding using the transmission line state enables high-gain transmission, and simple demodulation processing on the receiving side. Good transmission characteristics can be obtained. However, when applying precoding, as in the STBC method and the SFBC method, it is necessary for the receiving side to estimate all the transmission line states between each transmitting antenna and the receiving antenna, and to inform the transmitting side of the estimation result. That is, there is a drawback that the system is complicated because the receiving side feeds back the estimated value of the transmission line state.

In this way, various transmission diversity methods have advantages and disadvantages. Therefore, in order to obtain diversity gain and improve communication quality, system requirements such as transmission rate, CNR (Carrier power to Noise power Ratio) operating point, movement speed of the receiving side as seen from the transmitting side, transmission path condition, etc. Therefore, it is desirable to select the transmission diversity method to be used. For example, in the invention described in Patent Document 1, spatiotemporal transmission diversity is used when the moving speed of the receiving side is high, and phase control diversity is used when the moving speed is low to improve communication efficiency. There is.

Japanese Patent No. 3877713

Considering the simplification of the communication system, it is desirable that the transmission diversity method to be used is one method. In addition, since the configuration is complicated even when the control signal is exchanged between the wireless communication devices during the communication period, the wireless communication device that performs transmission diversity uses the signal received from the wireless communication device of the communication partner. It is desirable to perform transmission diversity control. Therefore, we consider the adoption of the simplest delayed transmission diversity method as the transmission diversity.

In the case of the delayed transmission diversity method, the transmitting side does not need feedback information from the receiving side. However, in the case of the delayed transmission diversity method, there is a problem that the transmission characteristics deteriorate under certain specific conditions. For example, when there are two transmitting antennas and one receiving antenna, if the difference in amplitude of the transmission path value from each transmitting antenna to the receiving antenna becomes small, a sharp drop in gain occurs at a specific frequency within the occupied bandwidth. Occurs. In this state, if the weight of the least squares error is used in frequency domain equalization, intersymbol interference remains in the received signal after equalization in order to give up complete reproduction of spectral distortion and avoid noise enhancement. Transmission characteristics deteriorate. In particular, when the wireless communication device approaches a stationary environment, the change in the transmission line is extremely gradual, so that the state in which the transmission characteristics are deteriorated continues for a long time. In this case, by turning off the transmission from one of the transmitting antennas, it is possible to eliminate the steep drop on the frequency axis and prevent the transmission characteristics from deteriorating. However, it is necessary to estimate with high accuracy whether or not the wireless communication device is stationary, and if the estimation accuracy is low, transmission cannot be stopped at the correct timing, and the transmission characteristics are deteriorated. There's a problem.

The present invention has been made in view of the above, and an object of the present invention is to obtain a wireless communication device capable of improving transmission characteristics in a communication system to which a delayed transmission diversity method is applied.

In order to solve the above-mentioned problems and achieve the object, the present invention is a wireless communication device provided with a plurality of antennas and capable of transmission processing using a delayed transmission diversity, and the transmission obtained by the first method. The state estimation unit that estimates the moving state of the wireless communication device based on the road estimated value and the transmission line estimated value obtained by the second method, and the moving state are in a state in which the transmission characteristics deteriorate when delayed transmission diversity is performed. When it is estimated by the state estimation unit that it is applicable, the process of stopping the use of the delayed transmission diversity, the process of changing the phase of the signal transmitted from some antennas among multiple antennas, or the process of transmitting from some antennas. A transmission device that performs processing for giving a frequency deviation to a signal is provided.

The wireless communication device according to the present invention has an effect that the transmission characteristics in the communication system to which the delayed transmission diversity method is applied can be improved.

The figure which shows the configuration example of the transmission apparatus provided in the base station of the communication system which concerns on Embodiment 1. The figure which shows the configuration example of the mobile station of the communication system which concerns on Embodiment 1. A flowchart showing an example of the operation of the transmission operation control unit included in the transmission device of the mobile station according to the first embodiment. A flowchart showing an example of an operation in which the shielding determination unit of the transmission operation control unit according to the first embodiment performs the shielding determination. A flowchart showing an example of an operation in which the state estimation unit of the transmission operation control unit according to the first embodiment estimates the state of the transmission line. A flowchart showing an example of an operation in which the state estimation unit of the transmission operation control unit according to the first embodiment estimates the movement state of the mobile station. The figure which shows an example of the hardware which realizes the mobile station which concerns on Embodiment 1. The figure which shows the configuration example of the communication system which concerns on Embodiment 2.

The wireless communication device, communication system, and wireless communication method according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment. In the following embodiment, an example will be described in which a communication system composed of a base station and a mobile station is assumed and the transmission diversity of the mobile station is controlled based on the reception result of a signal from the base station. In the following embodiments, the mobile station corresponds to the wireless communication device according to the present invention. Although the details will be described in the first embodiment, the mobile station obtains a two-dimensional transmission line estimation value using a signal received from the base station, that is, obtains two types of transmission line estimation values by different methods. , The moving state of the mobile station is estimated based on the obtained two types of transmission line estimated values. Further, the mobile station uses a plurality of carriers to determine whether or not the signal transmitted from each antenna is shielded, and selects an antenna to be turned off when the transmission is turned off based on the determination result.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a transmission device included in a base station of the communication system according to the first embodiment. Although the base station includes a receiving device in addition to the transmitting device, the receiving device of the base station is not required in the description of the mobile station which is the wireless communication device according to the first embodiment. Therefore, the receiving device is described in FIG. It is omitted.

The transmission device 101 constituting the base station 100 includes a plurality of transmission units 1-1 to 1-N _ca , each of which performs transmission processing for single carrier transmission. The transmission unit 1-1 transmits a signal on the first carrier (carrier # 1). Similarly, the transmission unit 1-N _ca transmits a signal with a carrier (carrier #N _ca) of the N _ca. Since the configurations of the transmission units 1-1 to 1-N _ca are the same, the transmission unit 1-1 will be described below.

The transmission unit 1-1 of the transmission device 101 includes a plurality of transmission processing units 10-1 to 10-N _t . The transmission processing unit 10-1 generates a signal to be transmitted from the first antenna (antenna # 1) among the plurality of antennas 19 included in the transmission device 101. Similarly, the transmission processing unit 10-N _t generates a signal to be transmitted from the antenna of the N _t of the plurality of antennas 19 (antennas #N _t). Since the configurations of the transmission processing units 10-1 to 10-N _t are the same, the transmission processing unit 10-1 will be described below.

The transmission processing unit 10-1 includes an error correction coding unit 11, an interleaver 12, a mapping unit 13, an interpolation unit 14, a band limiting unit 15, a DAC (Digital to Analog Converter) 16, and an analog front end 17. An antenna 19 is connected to the analog front end 17.

The error correction coding unit 11 error-corrects and encodes the bit sequence of the input transmission information, and inputs the coded bit sequence after the error correction coding to the interleaver 12. The interleaver 12 performs interleaving processing on the input coded bit sequence to change the order of the coded bit sequence. The interleaver 12 inputs the coded bit sequence after changing the order to the mapping unit 13.

The mapping unit 13 generates a symbol sequence by performing a mapping process corresponding to the modulation method to be used on the coded bit sequence input from the interleaver 12. Examples of the modulation method used by the transmission device 101 are PSK (Phase Shift Keying), QAM (Quadrature Amplitude Modulation), and the like. The mapping unit 13 inputs the generated symbol sequence to the interpolation unit 14.

The interpolation unit 14 performs an interpolation process for raising the sampling frequency of the symbol sequence input from the mapping unit 13, and inputs the obtained upsampled symbol sequence to the band limiting unit 15. The band limiting unit 15 performs band limiting processing on the input symbol sequence, and inputs the band-limited symbol sequence to the DAC 16. The DAC 16 converts the input symbol sequence from a digital signal to an analog signal, and inputs the converted analog signal, which is the symbol sequence, to the analog front end 17. The analog front end 17 up-converts and amplifies the analog signal input from the DAC 16 and inputs it to the antenna 19. The antenna 19 transmits the signal input from the analog front end 17 toward the mobile station.

Each transmission processing unit other than the transmission processing unit 10-1 also performs the same processing as the transmission processing unit 10-1, and a plurality of signals are transmitted in parallel from the plurality of antennas 19 of the transmission device 101 toward the mobile station. Each signal transmitted by the transmitting device 101 is received by the mobile station via a channel having fading. Here, if the mobile station has a plurality of receiving antennas, when the signal receiving antenna of the n _r of the mobile station receives a r _nr, the received signal r _nr is expressed by the following equation (1).

In the formula (1), h _{nr, nt,} the antenna of the n _t of the base station 100 (hereinafter referred to as transmitting antennas of the n _t) and the antenna of the n _r mobile stations (hereinafter, reception of the n _r It is a transmission line value indicating the state of the transmission line to and from (the antenna). d _nt is the signal to be transmitted from the transmission antenna of the n _t, n _nr is the noise at the receiving antenna of the n _r. Although expressed as a signal for each transmitting antenna here, the same signal may be transmitted from each antenna of the base station 100, transmission diversity, and spatial multiplexing can be supported, and there are no special restrictions.

FIG. 2 is a diagram showing a configuration example of a mobile station of the communication system according to the first embodiment. The mobile station 200 shown in FIG. 2 is composed of a receiving device 201 and a transmitting device 202. In FIG. 2, the receiving antenna 21 included in the receiving device 201 and the transmitting antenna 49 included in the transmitting device 202 are shown separately, but it is assumed that they are physically shared. That is, the mobile station 200 includes a plurality of antennas, and each antenna transmits and receives a signal. When the number of receiving antennas 21 for the mobile station 200 to receive the signal from the base station 100 is N _r , the number N _t of the transmitting antennas 49 for transmitting the signal is also the same (N _t = N _r ). is there.

The receiving device 201 constituting the mobile station 200 includes a plurality of receiving units 2-1 to 2-N _ca , each of which performs reception processing for single carrier transmission. The receiving unit 2-1 receives the signal on the first carrier (carrier # 1). Similarly, the receiving unit 2-N _ca receives a signal with a carrier (carrier #N _ca) of the N _ca. Since the configurations of the receiving units 2-1 to 2-N _ca are the same, the receiving unit 2-1 will be described below.

Reception unit of the reception apparatus 201 2-1 is provided with a plurality of reception processing units 20-1 ~ 20-N _r. The reception processing unit 20-1 processes the signal received by the first antenna (reception antenna # 1) among the plurality of reception antennas 21 included in the reception device 201. Similarly, the reception processing unit 20-N _r processes the signals received by the antenna of the N _r of the plurality of receiving antennas 21 (receiving antenna #N _r) receives. Since the configurations of the reception processing units 20-1 to 20-N _r are the same, the reception processing unit 20-1 will be described below.

The reception processing unit 20-1 includes an analog front end 22, an ADC (Analog to Digital Converter) 23, a band limiting unit 24, a decimation unit 25, a timing detection unit 26, a frequency correction unit 27, a transmission path estimation unit 28, and a signal reproduction unit. 29, an LLR (Log Likelihood Ratio) calculation unit 30, a deinteraver 31 and an error correction / decoding unit 32 are provided. A receiving antenna 21 is connected to the analog front end 22.

The analog front end 22 down-converts the signal input from the receiving antenna 21 and inputs the down-converted signal to the ADC 23. The ADC 23 converts the input analog signal into a digital signal, and inputs the digital signal to the band limiting unit 24. The band limiting unit 24 limits the band of the input digital signal and inputs the limited band digital signal to the decimation unit 25. The decimation unit 25 performs a decimation process for lowering the sampling rate of the input signal, and inputs the obtained downsampled signal to the timing detection unit 26.

The timing detection unit 26 detects the symbol timing of the input signal. The timing detection unit 26 detects the symbol timing by performing cross-correlation processing using a known preamble or the like included in the received signal. The received signal whose symbol timing is detected by the timing detection unit 26 is input to the frequency correction unit 27. The frequency correction unit 27 estimates the frequency deviation of the input received signal by using a known preamble or the like, and corrects the frequency of the received signal so that the frequency deviation becomes zero. The frequency correction unit 27 inputs the received signal after correcting the frequency to the transmission line estimation unit 28 and the signal reproduction unit 29.

The transmission line estimation unit 28 estimates the transmission line using a known pilot signal included in the received signal input from the frequency correction unit 27, and inputs the obtained transmission line estimation value to the signal reproduction unit 29. .. The signal reproduction unit 29 uses the transmission line estimation value input from the transmission line estimation unit 28 to perform synchronous detection and equalization processing on the received signal input from the frequency correction unit 27, and obtains a signal. Is input to the LLR calculation unit 30.

The LLR calculation unit 30 calculates the log-likelihood ratio (LLR) of each bit included in the signal input from the signal reproduction unit 29, and generates an LLR series. The LLR calculation unit 30 inputs the generated LLR series to the deinterleaver 31. The deinterleaver 31 deinterleaves the LLR series input from the LLR calculation unit 30 and rearranges the LLR series. Specifically, the deinterleaver 31 performs a process reverse to the process of changing the order of the coded bit sequences performed by the interleaver 12 of the transmission device 101, and returns the order to the original order. The deinterleaver 31 inputs the deinterleaved LLR sequence to the error correction / decoding unit 32. The error correction / decoding unit 32 error-corrects and decodes the LLR sequence input from the deinterleaver, and acquires the information bit sequence transmitted by the transmission device 101 of the base station 100.

Further, the transmission device 202 constituting the mobile station 200 includes a plurality of transmission units 4-1 to 4-N _ca , each of which performs transmission processing for single carrier transmission, and a transmission operation control unit 50. The transmission unit 4-1 transmits a signal on the first carrier (carrier # 1). Similarly, the transmitter 4-N _ca transmits a signal with a carrier (carrier #N _ca) of the N _ca. Since the configurations of the transmission units 4-1 to 4-N _ca are the same, the transmission unit 4-1 will be described below.

The transmission unit 4-1 of the transmission device 202 includes a plurality of transmission processing units 40-1 to 40-N _t . The transmission processing unit 40-1 generates a signal to be transmitted from the first antenna (transmission antenna # 1) among the plurality of transmission antennas 49 included in the transmission device 202. Similarly, the transmission processing unit 40-N _t generates a signal to be transmitted from the antenna of the N _t of the plurality of transmit antennas 49 (transmitting antenna #N _t). Since the configurations of the transmission processing units 40-1 to 40-N _t are the same, the transmission processing unit 40-1 will be described below.

The transmission processing unit 40-1 includes an error correction coding unit 41, an interleaver 42, a mapping unit 43, an interpolation unit 44, a band limiting unit 45, a diversity processing unit 46, a DAC 47, and an analog front end 48. A transmitting antenna 49 is connected to the analog front end 48.

The error correction coding unit 41 performs error correction coding on the bit sequence of the input transmission information, and inputs the coded bit sequence after the error correction coding to the interleaver 42. The interleaver 42 performs interleaving processing on the input coded bit sequence to change the order of the coded bit sequence. The interleaver 42 inputs the coded bit sequence after changing the order to the mapping unit 43.

The mapping unit 43 performs a mapping process corresponding to the modulation method to be used on the coded bit sequence input from the interleaver 42 to generate a symbol sequence. The mapping unit 43 inputs the generated symbol sequence to the interpolation unit 44.

The interpolation unit 44 performs an interpolation process for raising the sampling frequency of the symbol sequence input from the mapping unit 43, and inputs the obtained upsampled symbol sequence to the band limiting unit 45. The band limiting unit 45 performs band limiting processing on the input symbol sequence, and inputs the symbol sequence after band limiting to the diversity processing unit 46. In addition to the band-limited symbol sequence input from the band limiting unit 45, a control signal is input to the diversity processing unit 46 from the transmission operation control unit 50. The diversity processing unit 46 performs processing instructed by a control signal input from the transmission operation control unit 50. Specifically, the diversity processing unit 46 delays the band-limited symbol sequence input from the band-limited unit 45 and then outputs the symbol sequence, or band-limits the signal transmission by the transmitting antenna 49. Stops the output of later symbol series. When giving a delay to the symbol sequence after the band limitation, the diversity processing unit 46 holds the input symbol sequence for a time specified by the control signal, and then outputs the delay to the DAC 47. When the diversity processing units 46 of the transmission processing units 40-1 to 40-N _t give a delay to the input symbol series, the input symbol series are delayed by different delay amounts and output. As a result, delayed transmission diversity is realized. The DAC 47 converts the symbol sequence input from the diversity processing unit 46 from a digital signal to an analog signal, and inputs the converted analog signal, which is the symbol sequence, to the analog front end 48. The analog front end 48 up-converts and amplifies the analog signal input from the DAC 47, and inputs the analog signal to the transmitting antenna 49. The transmitting antenna 49 transmits the signal input from the analog front end 48 toward the base station 100.

For example, when Time Division Multiplexing Access (TDMA) is applied, the transmitting device 202 of the mobile station 200 performs burst transmission according to the frame timing estimated using the received signal from the base station 100. Will do. When the mobile station 200 utilizes a plurality of transmitting antennas 49 to perform delayed transmission diversity, for example, when utilizing N _t transmission antennas 49, the same transmission signal is transmitted with a delay, so that the base station 100 transmits. The received signal in the time domain is represented by the following equation (2). Here to be that the transmitting antennas of the n _t transmitting giving a delay of tau _nt.

When the received signal in the time domain represented by the formula (2) is frequency-converted, the received signal in the frequency domain represented by the following formula (3) is obtained.

Here, represented by H _nr (f) is the transmission path value has the following formula in the frequency domain of the frequency of the f at the receiving antenna of the n _r (4). The H _nr (f) is an equivalent transmission line transmission path condition is synthesized between the respective receive antennas of the n _r of the plurality of transmit antennas 49.

In the equation (4), τ _nt is the amount of delay given to the signal transmitted by the _ntth transmitting antenna, and N _c is the number of FFT (Fast Fourier Transform) points, as described above.

According to this transmission diversity method, even if the reception power of the transmission signal transmitted from a certain transmission antenna 49 in a mobile environment is attenuated by fading, it is repeatedly received by the same signal transmitted from the remaining transmission antennas, so that the influence of the attenuation is achieved. Can be reduced. However, since the transmission line state hardly changes when there is no movement, there may be a place on the frequency axis where the received signal component is extremely attenuated, depending on the combination of the transmission line coefficients in each transmission antenna. There is a problem that the transmission characteristics are significantly deteriorated due to this local attenuation. As described above, if a part of the transmitting antenna is stopped so that the equivalent transmission line does not suddenly drop in the frequency domain, the base station 100 confirms the channel quality of the uplink signal and the base station 100 moves to the mobile station 200. The above problem can be easily avoided without giving feedback on the above information.

Next, the transmission operation of the mobile station 200, that is, the operation in which the transmission device 202 transmits a signal to the base station 100 will be described.

As described above, the communication system according to the present embodiment is premised on the use of delayed transmission diversity. As described above, the transmission device 202 of the mobile station 200 includes transmission units 4-1 to 4-N _ca corresponding to each carrier and transmission operation control unit 50. Further, the transmission processing units 40-1 to 40-N _t included in each of the transmission units 4-1 to 4-N _ca include a diversity processing unit 46. The transmission operation control unit 50 includes a shielding determination unit 51 and a state estimation unit 52, and determines whether or not to perform delayed transmission diversity transmission. When performing delayed transmission diversity transmission, the transmission operation control unit 50 inputs a control signal including information on the amount of delay given to the signal transmitted from the transmission antenna 49 to each diversity processing unit 46. Further, the transmission operation control unit 50 determines from which transmission antenna 49 the transmission is stopped when the delayed transmission diversity transmission is not performed, and inputs a control signal including the determination result to each diversity processing unit 46. ..

The shielding determination unit 51 of the transmission operation control unit 50 determines for each transmission antenna 49 whether or not there is an object that shields radio waves between each transmission antenna 49 of the mobile station 200 and each antenna 19 of the base station 100. Further, the state estimation unit 52 of the transmission operation control unit 50 calculates an estimation error corresponding to an assumed moving speed candidate based on the moving state of the mobile station 200, specifically, the received signal from the base station 100. Then, it is estimated whether or not the self is stationary or moving at a low speed.

The control operation by the transmission operation control unit 50 will be described in detail with reference to FIGS. 3 to 6. FIG. 3 is a flowchart showing an example of the operation of the transmission operation control unit 50 included in the transmission device 202 of the mobile station 200 according to the first embodiment.

As shown in FIG. 3, the transmission operation control unit 50 first calculates an index value for shielding determination (step S11), and then performs transmission line estimation and interpolation processing (step S12). Next, the transmission operation control unit 50 estimates the moving state of the mobile station 200 by using the obtained transmission line estimation value, the interpolation value, and the index value for shielding determination (step S13). The moving state of the mobile station 200 estimates whether or not the mobile station 200 is stationary or moving at a low speed. In the following description, the state of moving at low speed is referred to as a quasi-stationary state. After that, the transmission operation control unit 50 determines the transmission antenna 49 to be turned off by using the index value for shielding determination (step S14). The determination result in step S14 includes the case where the transmission antenna 49 for turning off transmission does not exist.

Regarding shielding, it is physically possible to grasp only the downlink, even if it is not a Time Division Duplex (TDD) system in which the frequencies used for the uplink and downlink are the same. Utilizing this property, the shielding determination unit 51 included in the transmission operation control unit 50 of the transmission device 202 estimates the downlink received power and performs the shielding determination. The shielding determination is a determination as to whether or not there is shielding. Here, it is necessary to avoid erroneously determining that the state of being depressed by fading on the downlink is shielded. Therefore, the shielding determination unit 51 uses the received power of each of the plurality of carriers to prevent the above-mentioned erroneous determination from occurring. However, when the determination is performed using a plurality of adjacent carriers, the frequency correlation is relatively high, so that the drop in the received power due to fading may be determined as a shield. Therefore, the shielding determination unit 51 performs the shielding determination by using a plurality of carriers having a sufficiently small frequency correlation and a large separation frequency, that is, using all the carriers.

FIG. 4 is a flowchart showing an example of an operation in which the shielding determination unit 51 of the transmission operation control unit 50 according to the first embodiment performs the shielding determination.

First, the shielding determination unit 51 calculates the quality value of the received signals of the plurality of carriers (step S21). Specifically, the shielding determination unit 51 calculates SINR (Signal to Interference plus Noise Ratio) values _{Inr, no_ca} for the signal of each carrier received by each receiving antenna 21. nr indicates the number of the receiving antenna 21, and no_ca indicates the number of the carrier.

Next, the shielding determination unit 51 synthesizes the quality value of the received signal calculated in step S21 for each receiving antenna 21 and calculates an index value for shielding determination (step S22). Specifically, the shielding determination unit 51 synthesizes the above SINR values according to the following equation (5), and calculates an index value _Inr for shielding determination for each receiving antenna 21.

Next, the shielding determination unit 51 determines the presence or absence of shielding for each receiving antenna 21 by comparing the index value _Inr for shielding determination calculated in step S22 with the threshold value (step S23). It is estimated that the receiving antenna 21 corresponding to the index value _Inr below the threshold value is shielded from radio waves. As described above, since each antenna included in the mobile station 200 is used for both transmission and reception of signals, when the transmission antenna 49 corresponding to the reception antenna 21 whose index value _Inr is below the threshold value is used. Occurs shielding. Therefore, the transmitting antenna 49 corresponding to the receiving antenna 21 whose index value _Inr is below the threshold value is a target for turning off the transmission when the transmitting device 202 turns off the delayed transmission diversity.

For example, the plurality of receiving antennas 21 of the mobile station 200 are RX # n (n = 1, 2, 3, ...), And the receiving antenna 21 whose index value _Inr is lower than the predetermined threshold value th is RX # 1. In the case of, it can be determined that the radio wave received by RX # 1 is blocked. Here, when the plurality of transmitting antennas 49 of the mobile station 200 are TX # n (n = 1, 2, 3, ...) and RX # n and TX # n correspond to each other, the shielding determination unit 51 sets RX # 1 TX # 1 corresponding to is targeted for turning off transmission.

FIG. 5 is a flowchart showing an example of an operation in which the state estimation unit 52 of the transmission operation control unit 50 according to the first embodiment estimates the state of the transmission line.

The state estimation unit 52 estimates the transmission line using the pilot signal included in the signal received by the receiving device 201, and obtains the estimated transmission line value (step S31). The transmission line estimated value obtained in step S31 is represented by h _{pilot and nr} with a hat. Hereinafter, the h _{pilot and nr} with a hat will be referred to as "h _{pilot, nr} (hat)". The same description method is used when adding a hat to characters other than h _{pilot and nr} . The state estimation unit 52 obtains the estimated value of the transmission line at the position where the pilot signal does not exist by using linear interpolation or the like. The method of obtaining the transmission line estimated value in step S31 is the first method. The transmission line estimated value obtained by the first method is the first transmission line estimated value.

Next, the state estimation unit 52 transmits the assumed movement speed, the maximum multipath delay amount, and the received SNR (Signal-Noise Ratio) using a plurality of prepared interpolation tables a _tbl as a parameter set of the transmission line parameters. Path interpolation is performed (step S32). Specifically, the state estimation unit 52 acquires the transmission line interpolation value represented by the following equation (6) based on the transmission line estimation value at the position where the pilot signal exists and the interpolation table _atbl. .. The transmission line interpolation value is a transmission line estimated value calculated by transmission line interpolation performed using an interpolation table. The method of obtaining the transmission line estimated value in step S32 is the second method. The transmission line estimated value obtained by the second method is the second transmission line estimated value. In the present embodiment, the transmission line estimation value obtained by the transmission line interpolation in step S32 is referred to as a transmission line interpolation value in order to distinguish it from the transmission line estimation value obtained in step S31. The h _{int, nr} (hat) (t, f) represented by the equation (6) is a transmission line interpolation value calculated using the tbl number interpolation table, and more specifically, the fth frequency at the t time. It is a transmission line interpolation value.

The state estimation unit 52 then calculates the interpolation error corresponding to each interpolation table (step S33). Specifically, the state estimation unit 52 calculates the interpolation error _{et tbl} using the following equation (7). As shown in the equation (7), the state estimation unit 52 obtains the interpolation error _{et bl} from the difference between the transmission line interpolation value obtained by the transmission line interpolation and the transmission line estimation value obtained by using the pilot signal.

In equation (7), b is a set indicating the position where the pilot signal is inserted. The state estimation unit 52 calculates the interpolation errors of all the interpolation tables, and then selects the interpolation table having the smallest interpolation error. As described above, the interpolation table takes into account various situations assumed when the mobile station 200 communicates, that is, the assumed moving speed, maximum multipath delay amount and received SNR of the transmission line parameters. Multiple parameter sets are prepared. Of the transmission line interpolation values obtained by the state estimation unit 52 in step S32, the transmission line interpolation values obtained by using an interpolation table close to the actual situation of the mobile station 200 are obtained by the state estimation unit 52 in step S31. The difference from the estimated transmission line obtained directly from the pilot signal becomes smaller. Therefore, it can be estimated that the transmission line indicated by the transmission line parameter corresponding to the interpolation table having the smallest interpolation error is the most probable transmission line.

In the transmission line interpolation in step S32, the state estimation unit 52 calculates the transmission line interpolation value using the transmission line estimation values by a plurality of pilot signals based on the interpolation table. Since the transmission line interpolation value calculated in this way is noise-reduced while interpolating, the transmission line environment is more accurate than performing autocorrelation processing by directly using the transmission line estimated value obtained from the pilot signal. Can be detected with.

FIG. 6 is a flowchart showing an example of an operation in which the state estimation unit 52 of the transmission operation control unit 50 according to the first embodiment estimates the movement state of the mobile station 200.

After executing the above steps S31 to S33 shown in FIG. 5, the state estimation unit 52 synthesizes the interpolation errors of the plurality of carriers in order to improve the estimation accuracy of the transmission line parameters in the interpolation table (step S41). Specifically, the state estimation unit 52 calculates the combined interpolation error e _{total, tbl} , which is the combined result of the interpolation error, using the following equation (8).

In the equation (8), the synthesis coefficient c _{no_ca, nr} determined by the combination of the receiving antenna 21 and the carrier is multiplied by the interpolation error for synthesis, but the multiplication of the synthesis coefficient does not have to be performed. The combined coefficients c _{no_ca and nr} are calculated based on the received electric field strength and desired signal receiving power of each receiving antenna 21, each carrier, noise power and interference power, and the shielding determination result. For example, the synthesis coefficients c _{no_ca and nr} are calculated using the following equation (9). According to this, the synthesis coefficient c _{No_ca} antenna index value I _nr for shielding determination corresponding in the case of less than the threshold value _{th, nr} is 0, since unnecessary to accumulation in interpolation error synthesis process , The influence of noise can be reduced.

Next, the state estimation unit 52 synthesizes the interpolation errors of the front and rear frames in order to be able to follow the fluctuation of the moving speed of the mobile station 200 (step S42). Specifically, the state estimation unit 52 performs weighted synthesis using the forgetting coefficient α for the composite interpolation error calculated in step S41 and the two composite interpolation errors calculated at the times (frames) before and after. .. It should be noted that 0 <α <1.

Next, the state estimation unit 52 estimates the moving state of the mobile station 200 (step S43). Specifically, the state estimation unit 52 compares each of the combined interpolation errors obtained by executing the processes up to step S42 described above using each interpolation table, and identifies the interpolation table that minimizes the combined interpolation error. To do. When the specified interpolation table is premised on a stationary or quasi-stationary state, the state estimation unit 52 determines that the mobile station 200 is stationary or quasi-stationary. Then, the state estimation unit 52 decides to stop the delayed transmission diversity. When the delayed transmission diversity is stopped, the state estimation unit 52 preferentially determines the transmission antenna 49 determined by the occlusion determination unit 51 that the occlusion has occurred to the transmission antenna 49 that stops the transmission. When there is a transmitting antenna 49 with shielding, transmission using this is preferentially turned off, so that the delayed transmission diversity is stopped leaving the transmitting antenna 49 with shielding, and transmission is performed. It is possible to prevent the characteristics from deteriorating.

By the way, if interference is mixed in any of the bands of the multiple carriers used, there is a possibility of erroneous judgment if the moving state is judged using only the received power. Assuming such a case, the transmission operation control unit 50 obtains the signal power to interference and noise power ratio by utilizing the section where the frequency component is null in the transmission signal, and also obtains the signal power to interference and noise power ratio. It may be used to perform the index value calculation process for shielding determination in step S22 and the interpolation error synthesis process in step S41.

The transmission operation control unit 50 receives a reception signal from the reception antenna 21 of the reception device 201, and the shielding determination unit 51 and the state estimation unit 52 obtain necessary information based on the received reception signal. It is not limited to the configuration. The shielding determination unit 51 and the state estimation unit 52 may acquire a part of necessary information from the receiving device 201 and perform the above-described processing. For example, the transmission line estimation unit 28 of the receiving device 201 may calculate the above interpolation error used by the state estimation unit 52 and pass it to the state estimation unit 52. With such a configuration, the effect of reducing the circuit scale can be expected.

As described above, the mobile station 200 operating as the wireless communication device according to the present embodiment is a signal transmitted / received to / from the base station 100 based on the quality of each of the plurality of carriers received by each of the plurality of antennas. It is determined for each antenna whether or not the shielding has occurred. Further, the mobile station 200 uses a transmission line estimated value obtained by using the pilot signal and the interpolation processing, and a plurality of interpolation tables prepared in consideration of various situations assumed as the pilot signal. Based on the obtained transmission line estimation value and the transmission line interpolation value, the self-moving state is determined. Then, the mobile station 200 stops the delayed transmission diversity when its moving state is stationary or quasi-stationary. Further, when the mobile station 200 stops the delayed transmission diversity, the mobile station 200 preferentially stops the transmission using the antenna in which the occlusion occurs. The mobile station 200 according to the present embodiment can accurately determine its own moving state, and can stop the delayed transmission diversity when the transmission characteristic deteriorates when the delayed transmission diversity is performed. Therefore, according to the mobile station 200 according to the present embodiment, the transmission characteristics can be improved.

It is not essential to determine whether or not signal occlusion has occurred. When the mobile station 200 determines at least its own moving state, determines whether or not the transmission characteristics are deteriorated when the delayed transmission diversity is performed, and determines that the delayed transmission diversity should be stopped. That is, the delayed transmission diversity may be stopped when the moving state is stationary or quasi-stationary.

Further, in the present embodiment, when the mobile environment is in a quasi-stationary state or stationary, the delayed transmission diversity is stopped, and in this case, the transmission antenna that estimates the shielding status of each transmission antenna and turns off the transmission is appropriately selected. I tried to do it, but it is not limited to this. As a control of delayed transmission diversity, instead of turning off transmission when it is determined that the mobile environment is in a semi-stationary state or stationary, a phase change or waveform power fluctuation is given to the transmitted signal, or a frequency deviation is given. Therefore, deterioration of transmission characteristics may be avoided, and there is no particular limitation.

Next, the hardware configuration of the mobile station 200 will be described. Of the components of the receiving device 201 and the transmitting device 202 of the mobile station 200, the remaining components excluding the receiving antenna 21 and the transmitting antenna 49 can be realized by a dedicated processing circuit that realizes the mobile station 200. it can. The dedicated processing circuit is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit in which these are combined. ..

Each of the above components may be realized by a control circuit including the processor 301 and the memory 302 shown in FIG. FIG. 7 is a diagram showing an example of hardware for realizing the mobile station 200 according to the first embodiment. The processor 301 is a CPU (also referred to as a Central Processing Unit, a central processing unit, a processing unit, a computing device, a microprocessor, a microprocessor, a processor, or a DSP (Digital Signal Processor)). The memory 302 is non-volatile, such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EEPROM (Erasable Programmable Read Only Memory), EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), and the like. Alternatively, it is a volatile semiconductor memory.

When the remaining components excluding the receiving antenna 21 and the transmitting antenna 49 of the mobile station 200 are realized by the processor 301 and the memory 302 shown in FIG. 7, a program for operating as each of these components is previously provided in the memory 302. Store it. The processor 301 operates as each of the above components by reading and executing the program stored in the memory 302.

Of the components other than the receiving antenna 21 and the transmitting antenna 49 of the mobile station 200, a part may be realized by a dedicated processing circuit, and the rest may be realized by the processor 301 and the memory 302 shown in FIG. ..

Although the hardware configuration of the mobile station 200 has been described, the base station 100 can also be realized with the same hardware.

Embodiment 2.
In the first embodiment, the delayed transmission diversity is stopped whenever it is determined that the mobile station is stationary or quasi-stationary. In fact, the only case where the delayed transmission diversity should be stopped is when intersymbol interference increases, that is, there is a sharp drop on the frequency axis. In the first embodiment described above, even if it is not necessary to stop the delayed transmission diversity, the transmission may be turned off, so that performance improvement becomes an issue. The present embodiment solves the above-mentioned problems.

FIG. 8 is a diagram showing a configuration example of the communication system according to the second embodiment. The communication system according to the present embodiment includes a plurality of mobile stations 400 to 403, a plurality of base stations 406 to 408, a host device 500, and a data storage device 501. In this embodiment, as shown in FIG. 8, it is premised on a communication system in which a mobile station travels back and forth between a limited number of routes. In the example shown in FIG. 8, mobile stations 400 and 401 are stationary and

mobile stations

402 and 403 are moving. The configurations of the mobile stations 400 to 403 are the same as those of the mobile station 200 described in the first embodiment. Further, the configurations of the base stations 406 to 408 are the same as those of the base station 100 described in the first embodiment. Hereinafter, the operation of each device constituting the communication system shown in FIG. 8 will be described.

In the communication system shown in FIG. 8, the base stations 406 to 408 use the mobile station 400 based on the received signal from the mobile stations 400 to 403 each time the mobile stations 400 to 403 go back and forth between the

fixed routes

404 and 405. It is determined whether or not to stop the delayed transmission diversity by obtaining the frequency response of ~ 403. Then, the base stations 406 to 408 generate the delayed transmission diversity ON / OFF information Div _OnOff indicating the determination result, and transmit the operation record information 409 together with the position information indicating the positions of the mobile stations 400 to 403 to the _host device 500. To do. The method for the base station 406-408 to generate a determination to delay transmission diversity ON / OFF information Div _OnOff whether to stop the delay transmit diversity will be described later. In addition, base stations 406 to 408 shall periodically acquire position information from mobile stations 400 to 403. That is, the mobile stations 400 to 403 acquire and transmit their own position information at a predetermined cycle while communicating with the base stations 406 to 408. The mobile stations 400 to 403 may acquire the position information by any method.

When the host device 500 receives the operation record information 409, that is, the delayed transmission diversity ON / OFF information Div On Off and the position information from the base stations 406 to 408, the _host device 500 associates them and stores them in the database held by the data storage device 501. ..

Of the mobile stations 400 to 403, the stationary mobile stations 400 and 401 acquire the operation determination information 502 from the host device 500 in advance (that is, before starting the movement) via the base station 406 or 408. To do. The operation determination information 502 is information stored in the database of the data storage device 501, and includes the above-mentioned delayed transmission diversity ON / OFF information Div _OnOff and the position information associated _therewith . Host device 500 receives the request from the mobile station 400 or 401, reads all of the delay transmit diversity ON / OFF information Div _OnOff and location information stored in the database of the data storage device 501, the operation determination information 502 Is transmitted to base station 406 or 408. The host device 500 acquires information on the route on which the mobile station 400 or 401 requesting the operation determination information 502 travels, and the delayed transmission diversity ON / OFF corresponding to the route on which the mobile station 400 or 401 travels. The information Div On _Off and the position information may be extracted from the database and transmitted as the operation determination information 502.

The base station 406 or 408 transmits the operation determination information 502 received from the host device 500 to the mobile station 400 or the mobile station 401. When the mobile stations 400 and 401 receive the operation determination information 502, they hold the operation determination information 502, and after starting the movement, perform a transmission operation based on the held operation determination information 502. That is, the mobile stations 400 and 401 determine whether or not to perform the delayed transmission diversity in the transmission operation after the start of movement based on the operation determination information 502. More specifically, the mobile station 400 and 401, if the self indicating the current location and location information associated with that delay transmit diversity ON / OFF information Div _OnOff indicates diversity ON performs delay transmit diversity. Mobile station 400 and 401, if the self indicating the current location and location information associated with that delay transmit diversity ON / OFF information Div _OnOff indicates diversity OFF is not performed delay transmit diversity.

Next, a method of determining whether or not the base stations 406 to 408 stop the delayed transmission diversity will be described.

Delayed transmission diversity ON / OFF information Div _OnOff is generated by a receiving device that receives signals from mobile stations 400 to 403 at base stations 406 to 408. Specifically, the receiving devices of the base stations 406 to 408 perform transmission line estimation processing and interpolation processing using the pilot signal included in the reception signal, and calculate the transmission line estimation value H (f) in the frequency domain. The configuration of the receiving device of the base stations 406 to 408 is the same as that of the receiving device 201 of the mobile station 200 described in the first embodiment. After calculating the transmission line estimated value H (f) in the frequency domain, the receiving device _obtains the maximum value H _{_abs max} and the minimum value H _{_abs} min of the amplitude of the transmission line estimated value H (f). This process can be expressed by, for example, the following equation (10).

Next, the receiving device calculates the difference Diff between the maximum value and the minimum value of the amplitude of the transmission line estimated value H (f) as shown in the following equation (11).

Then, when the difference Diff is equal to or higher than the predetermined threshold value th or more, the receiving device considers that the influence of intersymbol interference at the time of stop is large and determines that the delayed transmission diversity should be turned off, and the difference Diff is performed. If it is less than the threshold value, it is determined that the transmission diversity should be turned ON. This process can be expressed by, for example, the following equation (12). In the formula (12), "0" represents the transmission diversity OFF, and "1" represents the transmission diversity ON.

Note that when the receiving device is performing reception diversity, the above difference Diff may be calculated for each receiving antenna and then combined. The same applies when there are a plurality of single carriers, and the above is not limited.

Next, the operation of mobile stations 400 to 403 will be described. It is assumed that the mobile stations 400 to 403 have acquired the above-mentioned operation determination information 502 (delayed transmission diversity ON / OFF information Div On Off and position information) from the _host device 500 via the base station 406 or 408. ..

After starting the movement along the

route

404 or 405, the mobile stations 400 to 403 determine their own movement state by using the method described in the first embodiment. When the mobile stations 400 to 403 determine that the moving state is stationary or semi-stationary, the delayed transmission diversity ON / OFF information associated with the position information indicating the current position is obtained from the held operation determination information 502. The Div On _Off is read, and the transmission operation is performed according to the read Div On _Off . In other words, the mobile station 400-403, if the read Div _OnOff is to stop delay transmit diversity If it shows a delay transmission diversity OFF, read Div _OnOff indicates a delayed transmission diversity ON, Delay Transmit Diversity If this is the case, this is continued, and if the delayed transmission diversity is stopped, the delayed transmission diversity is started.

As described above, in the communication system according to the second embodiment, the base stations 406 to 408 calculate the transmission line estimated value by using the pilot signal included in the received signal from the mobile stations 400 to 403, and the transmission line estimated value is calculated. Whether or not to stop the delayed transmission diversity is determined based on the maximum amplitude and the minimum amplitude of. The host device 500 stores the determination results of the base stations 406 to 408 in the database of the data storage device 501 in association with the position information indicating the position where the signal used for the determination is transmitted. Before starting the movement, the mobile stations 400 to 403 acquire the determination result and the position information stored in the database from the host device 500, and based on the acquired determination result and the position information, the delayed transmission diversity ON / Switch off.

According to the communication system according to the present embodiment, each mobile station (mobile stations 400 to 403) knows in advance where it is not necessary to turn off the delayed transmission diversity, so that the place where it is not necessary to turn off is erroneous. It is possible to prevent the transmission characteristics from deteriorating due to being turned off by the determination. In addition, in order to obtain the pre-required data (Delay Transmit Diversity ON / OFF information Div _OnOff and position information), the mobile station exchanges control signals with the base station 406-408 is unnecessary in the mobile system Can be simplified.

In this embodiment, the base station 406-408 is a comprise data storage device 501 a database for storing the delay transmit diversity ON / OFF information Div _OnOff and position information transmitted by the higher-level device to the database 500 May be prepared.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1-1,1-N _ca , 4-1,4-N _ca transmitter, 2-1,2-N _ca receiver, 10-1,10-N _t , 40-1, 40-N _t transmission processing Part, 11,41 Error correction coding part, 12,42 Interleaver, 13,43 Mapping part, 14,44 Antenna part, 15,24,45 Band limiting part, 16,47 DAC, 17,22,48 Analog front-end, 19 antenna, 20-1,20-N _r reception processing unit, 21 receiving antennas, 23 ADC, 25 decimation section, 26 timing detector, 27 a frequency correction unit, 28 channel estimation unit, 29 signal reproduction section, 30 LLR calculation unit, 31 deinterleaver, 32 error correction / decoding unit, 46 diversity processing unit, 49 transmission antenna, 50 transmission operation control unit, 51 shielding judgment unit, 52 state estimation unit, 100, 406, 407, 408 base stations, 101,202 transmitter, 200,400,401,402,403 mobile station, 201 receiver, 500 host device, 501 data storage device.

Claims

It is a wireless communication device equipped with multiple antennas and capable of transmission processing using delayed transmission diversity.
A state estimation unit that estimates the moving state of the wireless communication device based on the transmission line estimated value obtained by the first method and the transmission line estimated value obtained by the second method.
A process of stopping the use of the delayed transmission diversity when the state estimation unit estimates that the moving state corresponds to a state in which the transmission characteristics deteriorate when the delayed transmission diversity is performed, a part of the plurality of antennas. A transmission device that changes the phase of the signal transmitted from the antenna of the above or performs a process of giving a frequency deviation to the signal transmitted from some of the antennas.
A wireless communication device characterized by comprising.
A shielding determination unit that calculates the quality of the signal received by each of the plurality of antennas and determines whether or not the signal transmitted from each of the plurality of antennas is shielded based on the calculated quality.
With
When the transmitting device performs a process of stopping the use of the delayed transmission diversity, the transmission from the antenna determined by the shielding determination unit is stopped when the signal to be transmitted is shielded.
The wireless communication device according to claim 1.
The shielding determination unit obtains the quality of the received signals of a plurality of carriers having a small frequency correlation for each of the plurality of antennas, synthesizes the obtained quality, calculates an index value for shielding determination, and calculates the index. The value is compared with the threshold to determine if the occlusion occurs.
2. The wireless communication device according to claim 2.
The state estimation unit
In the first method, the known signal included in the received signal and the interpolation process are used to obtain the first transmission line estimated value.
In the second method, the known signal and a plurality of interpolation tables created for each of the plurality of assumed moving states are used, and each is one-to-one with one of the plurality of interpolation tables. Find the corresponding second transmission line estimates in
Among the obtained plurality of second transmission line estimated values, the moving state assumed by the interpolation table corresponding to the second transmission line estimated value having the smallest error from the first transmission line estimated value is described. Estimated to be the moving state of the wireless communication device,
The wireless communication device according to any one of claims 1 to 3, wherein the wireless communication device is characterized.
The state estimation unit
For each of the plurality of carriers received by each of the plurality of antennas, the error between the first transmission line estimated value and each of the plurality of second transmission line estimated values is obtained, and the obtained errors for each carrier are combined. The moving state assumed by the interpolation table corresponding to the second transmission line estimated value having the smallest error after synthesis obtained is estimated as the moving state of the wireless communication device.
The wireless communication device according to claim 4, wherein the wireless communication device is characterized.
When there is an antenna that shields the transmitted signal among the plurality of antennas,
The state estimation unit excludes the error corresponding to the carrier received by the antenna in which the shielding occurs, and performs a process of synthesizing the obtained error for each carrier.
The wireless communication device according to claim 5.
With base stations and higher-level equipment,
Mobile stations capable of transmission processing using delayed transmission diversity and
With
Each time the base station receives a signal from the mobile station, the base station determines whether or not to stop the delayed transmission diversity based on the received signal, and associates the determination result with the position information of the mobile station. Send to higher-level device,
The host device transmits the determination result and the position information received and held from the base station to the mobile station before starting the movement.
The mobile station
It corresponds to the moving state in which the transmission characteristics deteriorate when the delay transmission diversity is performed by estimating the own moving state based on the transmission line estimated value obtained by the first method and the transmission line estimated value obtained by the second method. Then, based on the determination result and the position information acquired from the higher-level device and the current position of the self, it is determined whether or not to continue the delayed transmission diversity.
A communication system characterized by that.
It is a wireless communication method executed by a wireless communication device equipped with multiple antennas and capable of transmission processing using delayed transmission diversity.
The first step of estimating the moving state of the wireless communication device based on the transmission line estimated value obtained by the first method and the transmission line estimated value obtained by the second method, and
In the first step, when it is estimated that the moving state corresponds to a state in which the transmission characteristics deteriorate when the delayed transmission diversity is performed, a process of stopping the use of the delayed transmission diversity, a part of the plurality of antennas. The second step of changing the phase of the signal transmitted from the antenna of the above or the process of giving a frequency deviation to the signal transmitted from the part of the antennas.
A wireless communication method characterized by including.