JP4952417B2 - Wireless communication apparatus and transmission channel state display method - Google Patents

Description

  The present invention relates to a wireless communication apparatus that performs high-speed spatial multiplexing communication using a plurality of antennas, and a transmission channel state display method.

At present, a method mainly used in home wireless LAN (Local Area Network) is IEEE (The Institute of Electrical and Electronics Engineers) 802.11a using 5.2 [GHz] band as a carrier frequency, or IEEE 802.11b and 802.11g using the 2.4 [GHz] band.
IEEE 802.11a and 802.11g adopt an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme, which is one of the multicarrier schemes, as a wireless LAN standard. In the OFDM modulation method, transmission data is distributed and transmitted to a plurality of carriers having mutually orthogonal frequencies set, so that the bandwidth of each carrier is narrow, the frequency utilization efficiency is very high, and frequency selective fading interference Strong.
These IEEE802.11a and IEEE802.11g have a maximum data transmission speed of 54 [Mbps] in the physical layer, a maximum of 30 [Mbps] in the MAC (Media Access Control) layer, and effective in TCP (Transport Control Protocol) transmission. The maximum speed is about 20 [Mbps]. Recently, along with an increase in the amount of data information handled in the world, research and development of wireless communication methods for realizing higher transmission speeds have become active.

For example, IEEE802.11a and IEEE802.11g, an extension standard of IEEE802.11g, propose a transmission rate exceeding 100 [Mbps], and OFDM_MIMO using OFDM for primary modulation in task group n (TGn). Standardization work is being done on the method.
MIMO (Multi-Input Multi-Output) communication is a type of spatial multiplexing communication, which is a communication system that includes a plurality of antenna elements on both the transmitter side and the receiver side to realize a spatially multiplexed stream. . On the transmission side, for example, space time coding (STC) is performed on a plurality of transmission data and multiplexed, and the transmission data after encoding is distributed to N transmission antennas to transmit a channel (atmospheric transmission path). ). On the other hand, on the receiving side, the received signal received by the M receiving antennas via the channel is subjected to space time decoding based on the channel characteristics (see, for example, Patent Document 1). At this time, a known signal (for example, a pilot signal) is received, channel characteristics can be estimated from the received signal, and received data can be obtained without crosstalk between streams based on the estimated channel characteristics.
Ideally, only the smaller number (min [n, m]) of spatial streams is formed, and the transmission capacity is determined in direct proportion to the number (min [n, m]). According to the MIMO communication system, it is possible to increase the transmission capacity according to the number of antennas without increasing the frequency band, thereby achieving an improvement in communication speed.

For MIMO communication, the single stream mode of IEEE802.11a and IEEE802.11b / g that define currently popular wireless LAN communication, and IEEE802.11n under standard development, is SISO (Single Input Single Output). Specify communication.
In non-MIMO communication such as SIMO communication, the channel capacity is determined by the S / N ratio of the transmission path. Therefore, usually, the transmission channel state is detected by examining the S / N ratio. Further, in a mobile phone or the like, the radio wave state is detected based on the electric field strength or received power of the received signal. The radio wave state can be said to be a kind of “index for displaying the transmission channel state” in a broad sense.
Japanese Patent Laid-Open No. 10-84324

  In these currently used non-MIMO communications, generally, when the reception position moves from several tens [m] to several hundreds [m], the S / N ratio and the radio wave state change significantly to some extent. On the other hand, even in non-MIMO communication, for example, in a portable device that employs antenna diversity, the S / N ratio and the radio wave state may change depending on the direction of the antenna. Will not change significantly.

On the other hand, in MIMO communication, the reception characteristics (reception performance) such as transmission speed vary greatly even if the reception position is slightly changed. One reason is that in MIMO communication, the correlation between a plurality of antenna elements is greatly related to reception performance.
In MIMO communication, a plurality of receiving antennas are used. However, in a multipath environment, the receiving performance is determined by the direction of the antenna (the angle of the surface formed by the plurality of antennas with respect to the main radio wave flying direction, etc.). Further, although it is the same level or slightly less than that, it is observed that the channel capacity of the reception characteristics changes greatly depending on the reception position in the MIMO communication. In addition, in MIMO communication, a change in channel capacity that affects the transmission speed occurs only by moving a wireless communication device of about several [cm] to several tens [cm], and the reception position is unthinkable in non-MIMO communication. On the other hand, it has a unique characteristic that reception performance changes sensitively.

  The problem to be solved by the present invention is that a radio of a spatial multiplexing communication system configured to provide an index for determining an optimum reception position for a user who intends to perform spatial multiplexing reception in a state where transmission characteristics are as good as possible. It is to provide a communication device or a transmission channel state display method of spatial multiplexing communication.

A wireless communication apparatus according to an embodiment of the present invention is a wireless communication apparatus capable of spatial multiplexing communication between a plurality of transmission antennas and a plurality of reception antennas, and includes a channel capacity calculation unit, a channel state display unit, and a display And a control unit .
The channel capacity calculation unit calculates a channel capacity value of spatial multiplexing communication at the reception position of the wireless communication apparatus from the received signal.
The channel state display unit displays a transmission channel state according to the calculated channel capacity value.
The display control unit detects control information related to the priority of data from the received signal, and based on the detected control information, the higher the priority is, the range of the reception position that displays a better channel state. The channel state display unit is controlled to be narrow.
Alternatively, the display control unit detects control information related to the priority of data from the received signal, and based on the detected control information, the higher the priority, the better the reception position that displays the channel state. The channel state display unit is controlled so that the range becomes narrow.

  In the present invention, preferably, the channel state display unit compares the calculated channel capacity value with a predetermined threshold value, and when the magnitude relationship between the calculated channel capacity value and the threshold value is reversed, Change the display.

  According to the wireless communication apparatus related to the present invention having the above-described configuration, for example, the user moves the wireless communication apparatus forward and backward, left and right, or both while looking at the channel state display unit to change the reception position, and For the right receiving point. At this time, the channel capacity calculation unit in the wireless communication apparatus calculates the channel capacity from the received signal periodically, for example. Therefore, channel capacities at different reception points can be obtained. At this time, the channel state display unit performs channel display at each reception point based on the channel capacity corresponding to the point. Specifically, for example, multi-level display of channel states such as a so-called level indicator using LEDs or the like, or good / bad display of channel states in which different colors and brightness are changed by binary values can be adopted.

A transmission channel state display method according to an aspect of the present invention is a reception side of spatial multiplexing communication performed between a plurality of transmission antennas and a plurality of reception antennas, and a channel capacity value of spatial multiplexing communication at a reception position is determined from a reception signal. A step of calculating, a step of comparing the calculated channel capacity value with a predetermined threshold, a step of displaying a transmission channel state, and the transmission when the magnitude relationship between the calculated channel capacity value and the threshold is reversed. When changing the display of the channel state and changing the display, control information related to the priority of data is detected from the received signal, and the higher the priority is, the higher the priority is based on the detected control information, the transmission channel Reducing the sensitivity of the display change of the state to the magnitude of the channel capacity value .
In addition, a transmission channel state display method according to another aspect of the present invention provides a channel capacity value of spatial multiplexing communication at a reception position on the reception side of spatial multiplexing communication performed between a plurality of transmission antennas and a plurality of reception antennas. When the step of calculating from the received signal, the step of comparing the calculated channel capacity value with a predetermined threshold, the step of displaying the transmission channel state, and the magnitude relationship between the calculated channel capacity value and the threshold are reversed. The transmission channel state display is changed, and when the display is changed, control information related to the priority of data is detected from the received signal. Based on the detected control information, the higher the priority, the better Narrowing the range of the reception position for displaying the channel state.

  According to the present invention, for a user who wants to perform spatial multiplexing reception in a state where transmission characteristics are as good as possible, an index of “transmission channel state display” is provided, so that the reception position can be easily optimized. It is possible to receive a benefit that the wireless communication device can be used with good reception performance.

Embodiments of the present invention will be described below with reference to the drawings.
The present invention is widely applicable to wireless communication in which data is transmitted and received wirelessly with other wireless stations such as a wireless LAN or a PAN (Personal Area Network). Further, although the modulation scheme of wireless communication is not limited to OFDM, an embodiment of the present invention will be described below using, for example, an OFDM_MIMO scheme that complies with IEEE802.11n of a wireless LAN, for example.

  In general, the wireless communication function is installed in many communication terminal devices such as an information processing device such as a personal computer, a mobile phone, and a PDA (Personal Digital Assistance). Recently, various types of consumer electronic devices such as audio products, video devices, camera devices, printers, and entertainment robots have been equipped with wireless communication functions. Furthermore, the wireless communication function is not only an electronic device, but also an access point for wireless LAN, a PCMCIA specification (Personal Computer Memory Card International Association) card, a compact flash (registered trademark) card, a mini PCI (Peripheral Component Interconnection) card, etc. It is also mounted on the so-called small accessory card. For example, a wireless card module having a storage function and a wireless communication function is commercially available.

  The wireless communication apparatus according to the present embodiment may be an information processing device such as the personal computer described above, or a communication terminal device such as a mobile phone or a PDA. The wireless communication device according to the present embodiment may be a device in which a wireless communication function is installed in an electronic device such as an audio product, a video device, a camera device, a printer, or an entertainment robot.

  The wireless communication apparatus according to the present embodiment includes a “channel capacity calculation unit” and a “channel state display unit”. Although those functions will be described later, they can be realized as functions of a reception processing unit and a control unit such as a CPU. In addition, the channel state display unit can take various forms, such as when it is displayed with the brightness and color of light such as an LED, when it is realized as a part of the screen display unit, and when it is realized with loudness. .

Basically, the main body of the wireless communication apparatus includes a channel capacity calculation unit and a channel state display unit.
However, for example, in the case of an electronic component such as a card type having a wireless communication function or a wireless card module, the electronic component or the wireless card module may be detachably provided on the main body.
Both the channel capacity calculation unit and the channel state display unit may be provided in the detachable electronic component or the wireless card module. In this case, the detachable electronic component and the wireless card module alone constitute the “wireless communication apparatus” of the present embodiment.
On the other hand, a channel capacity calculation unit may be provided on the main body side, and a channel display unit may be provided on a removable electronic component, a wireless card module, or the like. In this case, the “wireless communication apparatus” of the present embodiment is configured by both the main body and accessories such as removable electronic parts and wireless card modules.
In these two forms, it is usually desirable to display the channel state by sound or light when it is impossible to display a large screen with a detachable electronic component or a wireless card module. However, a small screen display unit can be provided.

  Hereinafter, in the present embodiment, the reception position dependency of transmission characteristics in MIMO communication will be described first, and then the configuration and operation of a wireless communication apparatus that facilitates optimization of the reception position (transmission channel state display method of MIMO communication) Will be described.

<< Reception position dependence of transmission characteristics >>
As described above, the OFDM_MIMO system conforms to the IEEE802.11n standard, and this standard is an extension standard of IEEE802.11a and IEEE802.11g.
In any wireless system of these standards, the OFDM modulation scheme is adopted, and transmission on each subcarrier can be regarded as almost flat fading. Therefore, even in a relatively wideband communication system such as the IEEE 802.11n standard, the MIMO transmission path can be expressed with a somewhat simple model.

For example, as shown in FIG. 1A, the MIMO transmission path can be expressed as a MIMO communication model of 2 × 2 (two transmitting antennas, two receiving antennas). In FIG. 1, two antennas are assumed on each of the transmission side and the reception side, that is, two transmission antennas Ts1 and Ts2 and two reception antennas Tr1 and Tr2. The transmission characteristic elements between the antennas are indicated by symbols h ₁₁ , h ₁₂ , h ₂₁ , and h ₂₂ .

FIG. 1B shows a transmission formula for MIMO communication. The transmission signal s is expressed by a determinant of the transmission signal s _{1 at the} transmission antenna Ts ₁ and the transmission signal s ₂ at the transmission antenna Ts ₂ . Similarly, the received signal _{r 1} in the received signal r is also receiving antenna Tr1, represented by a matrix equation between the received signal _{r 2} at the receiving antenna Tr2.
In FIG. 1B, a symbol H indicates a matrix representing the transmission characteristics of the space (transmission path) between the transmission antenna pair and the reception antenna pair. This matrix is referred to as a transmission matrix H, and is a complex matrix (a matrix that gives amplitude fluctuation and phase rotation of the signal) that relates the transmission signal s and the reception signal r. The transmission matrix H can take various values depending on the state of the transmission path.

On the other hand, the channel capacity C [bps / Hz] of the transmission path can be expressed by the equation shown in FIG. 1C based on Shannon's communication capacity theorem. In this equation, symbol γ represents the S / N ratio, symbol M represents the number of streams in the MIMO system (min [n, m], where n is the number of transmitting antennas and m is the number of receiving antennas), and symbol λ _i represents each eigenvalue.
In an ideal state where the elements of the transmission matrix H are h ₁₁ = h ₂₂ = 1 and h ₁₂ = h ₂₁ = j as shown in (1) of FIG. 1D, the value of the channel capacity C is 2 × 2 MIMO. The maximum value in communication (= 2.00). On the other hand, when the elements of the transmission matrix H are h ₁₁ = h ₂₂ = h ₁₂ = h ₂₁ = 1 as shown in (2) of FIG. 1D, the value of the channel capacity C is 2 × 2 MIMO communication. The minimum value at (= 1.59).
In actual MIMO communication, the value of the channel capacity C takes a value corresponding to the reception environment within the range of the maximum value or less and the minimum value or more. In other words, when the value of the transmission matrix H is a parameter that changes arbitrarily, the channel capacity C has a certain distribution.

FIG. 2 is a diagram in which 1000 values of each element h ₁₁ , h ₁₂ , h ₂₁ , and h ₂₂ of the transmission matrix H are randomly generated, and the distribution of channel capacity values at that time is expressed by CDF (Cumulative Distribution Function). It is. From this figure, the value of the channel capacity C is widely distributed, and it can be seen that there is a state of the channel capacity C close to the lowest value (= 1.59) with a probability of just over 10% (CDF = 0.1). .

Next, an example is shown in which the reception position dependency of the channel capacity is obtained by actual measurement in an actual environment.
FIG. 3 shows the setup used to measure the channel capacity.
The transmitting antennas Ts1 and Ts2 are set on the table 101, and the receiving antenna Tr1 is set at a distance of 2.4 [m] therefrom. Here, 2 × 1 MIMO communication in which the number of transmission antennas is 2 and the number of reception antennas is 1 is assumed.
The positions of the transmission antennas Ts1 and Ts2 are fixed at a distance between antennas of 125 [mm], and the distance between the reception antennas Tr1 and Tr2 is fixed at several [mm] to several tens [mm]. In the figure, the receiving-side antenna body appears to be one, but this antenna body incorporates a fixed receiving antenna pair. Then, the position of the reception antenna pair (Tr1, Tr2) is shifted in parallel with the line between the transmission antennas to change the reception position. At this time, the step of shifting the position is equally spaced, and the channel capacity is calculated for each of the seven reception positions.

A metal box 103 for blocking direct wave arrival is placed as a barrier in the middle of the transmission path, and a reflection wall 102 is provided along the transmission path to make it as close as possible to the actual multipath environment. Has been.
One side of a transmission signal output cable (coaxial cable) is connected to transmission antennas Ts 1 and Ts 2, and the other side is connected to a signal output terminal of a VNA (Vector Network Analyzer) 105 installed in the shield room 104. Further, one side of the input cable (coaxial cable) of the reception signal is connected to the reception antenna Tr1, and the other side is connected to the signal input terminal (measurement terminal) of the VNA 105. Reference numeral 106 denotes a switch box, and a high-frequency antenna switch for switching the destination of the same transmission signal between the transmission antennas Ts1 and Ts2 is built in the box.

Using this setup, the receiving antenna pair (Tr1, Tr2) was translated six times in a predetermined step, and the transmission characteristics, specifically the channel capacity, were measured at seven receiving positions including the initial position.
FIG. 4 is a graph showing the measurement results. The horizontal axis in the figure represents the reception positions with numbers 1 to 7 in coordinates parallel to the line between the transmission antennas Ts1 and Ts2. When the receiving antenna Tr1 of the receiving antenna pair (Tr1, Tr2) is positioned at the coordinate origin (position coordinate ANT1 = 0 [mm]), “position 1” is obtained. At that time, the position coordinate ANT2 of the receiving antenna Tr2 is 10 [mm]. That is, the fixed distance between the receiving antennas Tr1 and Tr2 is 10 [mm]. A 2.4 [GHz] band MIMO channel capacity at position 1 was observed to be approximately 1.76 [bps / Hz]. This value is obtained by calculating the channel capacity at the center position (position coordinate: 5 [mm]) of the receiving antenna pair (Tr1, Tr2) from the equation shown in FIG.

The same calculation is performed at positions 2 to 7 shifted by 5 [mm], and the value of the channel capacity C at each reception position is obtained and plotted in FIG.
FIG. 4 shows that the propagation characteristics change depending on the position, and the channel capacity of 2 × 2 MIMO communication changes by 20% or more. And if such a situation is created and measured at random while adding factors such as the reception position shift not only to the left and right but also to the front and back and oblique to the transmission direction, the measurement result will be It is considered that the distribution (1.59 ≦ C ≦ 2.00) shown in FIG. 2 is approached.

In particular, in MIMO communication, the channel capacity C varies greatly with a slight position change of only 10 [mm], as is apparent from the shift position of position 2 → 3 → 4, for example, as shown in FIG.
In MIMO communication, the horizontally polarized wave and the vertically polarized wave are arranged so that the linearly polarized antenna is orthogonal, and the right polarized wave and the left polarized wave are arranged orthogonally for the circularly polarized antenna. By making each polarization orthogonal, the correlation between antennas can be reduced, thereby improving the quality of MIMO transmission. In a multipath environment, the reception state changes greatly depending on the direction. Therefore, in MIMO communication, the influence of antenna position dependency (and orientation dependency) on communication performance is stronger than non-MIMO communication.
Since the communication environment created experimentally in FIG. 3 is simpler than the actual communication environment, it is estimated that the channel capacity C of the MIMO communication changes greatly even if it is actually less than 10 [mm].

The above is an experiment on the position dependency of the receiving antenna of the transmission characteristics, but in MIMO communication, the correlation between antennas changes depending on the direction of the transmitting and receiving antennas and the distance between the antennas on both the transmitting side and the receiving side. To do.
Therefore, there are optimum values for each communication environment with respect to the transmission / reception antenna position and orientation, and the distance between the antennas on the transmission side and the reception side. That is, in MIMO communication, the maximum channel capacity that can be obtained varies depending on the position / direction relationship between both devices (antennas) that transmit and receive.
For this reason, if the MIMO communication antenna is used in an orientation and / or position where performance is not good, there is a possibility that the data rate required by the user cannot be obtained.

In order to solve this, for example, it is necessary to optimize the transmission characteristics by changing the polarization of the transmission / reception antenna.
When this optimization is performed on the receiving side, the state where the polarization planes of the antenna pair are orthogonal may not be optimal due to the relationship with the polarization of the transmitting antenna and the influence of a complicated multipath environment. Therefore, the optimization can be performed only in an actual communication environment.
However, in consumer products, it is not possible to require the user to change the polarization between antennas, specifically, to slightly change the direction of the antenna on one side. In addition, it is not possible to require the user to make adjustments that slightly change the distance between the antennas of the antenna pair, and there are many cases where such one-side antenna position adjustment cannot be performed particularly in a small portable device. For example, even if you change the orientation of the wireless communication device, for example, when you are sitting at a desk and working while using a LAN, changing the orientation makes it difficult to see the screen or it is difficult to work. There is a limit to change.

  Therefore, in the present embodiment, when the user changes the position of the antenna as determined in the experiment, the “premix” at that position, that is, before the fluctuation element is mixed by various signal processing ( In other words, the channel capacity C is obtained by calculation as an index of communication performance (in the state immediately after reception). At this time, the channel capacity C is calculated from the received signal, for example, by channel estimation. Then, by adding a utility tool capable of notifying the user of the change of the channel capacity C, the wireless communication device which allows the user to find the optimum communication point, and its transmission channel state display Provide a method.

  Hereinafter, a more detailed embodiment (configuration and operation) will be described using a small portable device as an example.

<< First Embodiment >>
<Device configuration>
FIG. 5 is a schematic configuration diagram showing functional blocks and UI (User Interface) of the wireless communication apparatus according to the present embodiment.
The illustrated wireless communication apparatus 1 includes a flat panel display (FPD, hereinafter simply referred to as “display”) 21 on the front surface of a housing 2. In addition, as another UI, an operation unit 25 provided on the front surface in a range indicated by a broken line in the drawing is provided. Furthermore, an audio output unit 23 such as a speaker and an optical display unit 24 such as an LED are also provided on the front surface of the housing 2 as necessary. A battery (BT) 22 detachable from the back surface or bottom surface of the housing 2 is built in the housing 2.

An antenna cover 2A is integrally formed with the housing 2 from resin or the like, and receiving antennas Tr1 and Tr2 are accommodated therein. The reception antennas Tr1 and Tr2 also serve as transmission antennas during transmission. The distance between the antennas of the receiving antennas Tr1 and Tr2 is fixed, for example, several [mm].
Note that the number of antennas is not limited to two and may be three or more. When switching between non-MIMO communication and MIMO communication is possible, one of the provided antennas is used for non-MIMO communication.

As an internal processing block, an RF (Radio Frequency) module 4 and a control unit 5 are provided on a mounting board (not shown).
The RF module 4 is a part that performs processing related to MIMO communication conforming to the IEEE802.11n standard, and is usually modularized around one or more ICs. Note that the RF module 4 means a processing part specific to the adopted wireless communication standard. In this sense, the same function can be realized even if it is not necessarily modularized.
Receiving antennas Tr1 and Tr2 are connected to the RF module 4 via RF cables, respectively, so that RF received signals can be processed by the RF module 4.

The control unit 5 is a circuit capable of high-speed computation that controls the entire wireless communication apparatus 1 including the display 21 and the RF module 4.
Note that the configuration for power control and the like is not shown, but the power from the battery 22 is appropriately converted to a necessary voltage level by the power control unit for the RF module 4, the control unit 5, the display 21, and the like. To be distributed.
Also, an IC for processing an application (software for realizing a function) is not shown.

  The modulation / demodulation method of MIMO communication employed in the RF module 4 is zero forcing, V-BLAST (Vertical Bell Labs Layered Space-Time), and the like. Demodulation method, MLD (Maximum Likelihood Detection) method, which demodulates by non-linear calculation, channel information is acquired in advance on the transmission side, and appropriate power distribution and phase vector synthesis are performed accordingly. Any method may be used among various methods such as eigen-mode MIMO. There is no limitation on the modulation / demodulation method of MIMO communication, and other methods may be used.

<RF module configuration>
FIG. 6 is a schematic block diagram showing the basic configuration of the RF module 4. FIG. 7 is a diagram showing the details of the reception process of FIG. 6 in more detailed functional blocks.
6 and 7 show configurations common to various modulation / demodulation schemes of the MIMO communication described above. Further, the configuration of the RF module 4 in FIG. 6 includes three transmission / reception paths that can be expanded to MIMO communication using three antennas. In the wireless communication device 1 shown in FIG. To perform MIMO communication.

The RF module 4 illustrated in FIG. 6 includes three duplexers 41_1 to 41_3 as circuit blocks that are built-in or controlled by a control unit (for example, CPU) 5 that controls the entire wireless communication device 1. And three RF reception processing units (RE.C) 42_1 to 42_3, three RF transmission processing units (TX.C) 43_1 to 43_3, one baseband and Mac processing unit (indicated as BB & MAC in the figure, the following) , BB / MAC processing unit) 44.
A single switch (not shown) can be connected to each input of the duplexers 41_1 to 41_3, and the duplexer switches the connection to the antenna by two paths (reception path and transmission path) to the RF module 4. It is. The RF reception processing unit 42_1 is connected to the reception path of the duplexer 41_1, and the RF transmission processing unit 43_1 is connected to the transmission path. The RF reception processing unit 42_2 is connected to the reception path of the duplexer 41_2, and the RF transmission processing unit 43_2 is connected to the transmission path. Further, the RF reception processing unit 42_3 is connected to the reception path of the duplexer 41_3, and the RF transmission processing unit 43_3 is connected to the transmission path.

First, a configuration for transmission processing and its operation will be briefly described.
In the BB / MAC processing unit 44, a configuration related to transmission processing is not particularly shown, but an error correction code unit that performs error correction coding on transmission data, an S / P (Serial to Parallel) conversion unit, a mapping processing unit, a high speed It includes an inverse fast Fourier transform (IFFT), a P / S (Parallel to Serial) conversion unit, a multiplex unit, guard interval insertion and a D / A (Digital to Analog) conversion post-processing unit.
Each of the RF transmission processing units 43 </ b> _ <b> 1 to 43 </ b> _ <b> 3 is not particularly shown in detail, but an encoding unit (for example, a quadrature modulation circuit (Quad. Demodulator)), an up-conversion unit, a power amplification circuit, and a bandpass filter Etc. are configured.

  The S / P conversion unit in the BB / MAC processing unit 44 receives transmission information from the upper layer protocol via the interface, and performs parallel-serial conversion of the transmission information into a data stream for each carrier. From the S / P converter, data streams for data necessary for modulation of each carrier are output in parallel, and each subcarrier is modulated in the mapping processing unit for each stream. In the mapping processing unit, for example, a transmission vector composed of a transmission data sequence for each stream is multiplied by an antenna transmission weight matrix to generate a spatially multiplexed transmission signal for each antenna transmission path. To calculate the antenna transmission weight matrix, a known method such as a method of calculating based on information fed back from a communication partner or a method of calculating from a channel matrix estimated by itself can be applied.

  Thereafter, the IFFT unit converts the frequency domain data signal into a time domain data signal (OFDM symbol). After the TFFT, the time domain data signal is converted into serial data by the P / S converter, and the control preamble is time-multiplexed by the multiplex part for the converted data, and then received by the post-processor. A transmission packet signal is generated by inserting a guard interval (GI) to reduce inter-symbol interference. The generated transmission packet signal is converted into an analog signal and then sent to the subsequent RF transmission processing unit.

  In each of the RF transmission processing units 43_1 to 43_3, the encoding unit (or quadrature modulation circuit) inputs an analog packet signal (baseband signal) to be transmitted from the BB / MAC processing unit 44, and the complex IQ space. Encode signal points (orthogonal modulation). Next, the signal after quadrature modulation is up-converted to an RF band by an up-conversion unit to generate an RF transmission signal. The RF transmission signal is subjected to power amplification by a power amplification circuit, and then passed through a band-pass filter that passes only a component in a desired band. Transmission signals (components of a desired band) from each RF transmission processing unit are connected to the antenna via a corresponding duplexer, and are emitted from the antenna into the air as an RF radio signal.

Next, a configuration for reception processing and its operation will be described.
Each of the RF reception processing units 42_1 to 42_3, although not specifically shown in detail, includes a bandpass filter, a low noise amplification circuit (LNA) that amplifies the received RF signal, a down-conversion unit that down-converts the RF signal, and A decoding unit (for example, a quadrature demodulator) that decodes the down-converted received signal into signal points on the complex IQ space is included.

  FIG. 7 shows a schematic block configuration in the BB / MAC processing unit 44 that receives and processes a baseband signal from the RF reception processing unit. In this figure, the circuit block is generalized with the reception path as N systems, but N = 3 in correspondence with FIG.

  As shown in FIG. 7, the BB / MAC processing unit 44 performs symbolic synchronization, GI removal (GI Remove), and periodic (time) expansion for removing gaps after GI removal as preprocessing for FFT, as shown in FIG. Cyclic (Time) Extension), a pre-processing unit (PRE.) 441 that performs S / P conversion, an FFT unit 442, a mapping processing unit (MAPUI (i = 1 to N)) 443, and demapping (Demapping) ), A post-processing unit (POST.) 444 that performs deinterleaving (decoding) and decoding (decoding).

The RF signal received by the antenna is sent to the corresponding RF reception processing units 42_1 to 42_N (42_3) through the corresponding duplexers 41_1 to 41_N (41_3).
The band-pass filter in the RF reception processing units 42_1 to 42_N (42_3) passes only the signal component of the desired band in the antenna reception signal (RF signal) from the duplexer. The RF signal from the bandpass filter is amplified by the LNA and then down-converted to a lower same frequency band where the signal can be easily handled. The down-converted received signal is orthogonally demodulated (or orthogonally decoded) and converted into a baseband signal having a real part and an imaginary part. The converted baseband signal is sent to the BB / MAC processing unit 44 in the subsequent stage.
Although not shown, the quadrature demodulation circuit is operated by a clock from a circuit unit that generates an operation clock and the like, generates two oscillation signals whose phases are different by 90 degrees, and changes the phase difference between the two sub-phases. The signal superimposed on the carrier signal is orthogonally demodulated.

In the BB / MAC processing unit 44, first, the preprocessing unit 441 performs OFDM symbol synchronization with reference to the preamble in the packet, and removes the guard interval (GI). Periodic (time) extension is performed for each packet to fill the gap after GI removal. The serial packet is converted into the number of serial data corresponding to the OFDM subcarrier by referring to the pilot signal. The pre-processed received packet is sent to the FFT unit 442.
The FFT unit 442 converts the input serial data (time domain data) into frequency domain data by FFT and performs OFDM demodulation on a plurality of subcarriers. A plurality of OFDM demodulated data is sent to the mapping processing unit 443. At this time, the same data is also input to the mapping processing units 443 of other reception paths.

In general, the mapping process performs various processes that require data to be used mutually while switching between a plurality of data. This process performed by the mapping processing unit 443 includes a MIMO reception process. At this time, a known training sequence is input for the MIMO reception process.
In the MIMO reception processing, for example, as one method, channel information (channel) is obtained by dividing a known (original) preamble signal from a preamble signal that has changed due to amplitude fluctuation and phase rotation according to the characteristics of the transmission channel. Matrix) (channel estimation). The same thing can be done using known signals and pilot signals.

Also, in MIMO communication reception, an antenna reception weight matrix is calculated based on the estimated channel matrix, and a reception vector composed of reception signals for each antenna reception path is multiplied by the antenna reception weight matrix to be spatially multiplexed. The received signal is spatially separated into subcarrier signals for each original stream. Further, in the MIMO reception process, a data series is decoded from each subcarrier on the frequency axis.
The decoded data series (N data series consisting of d _{1 to} d _Nt ) are mutually input to N post-processing units 444 and restored to transmission signals for each stream (reception path) by demapping. . Then, after serial conversion in the post-processing unit 444, the serial data is decoded into transmission data through error correction decoding (deinterleaving) and decoding.
The decrypted transmission data is passed to the processing unit performed by the upper layer protocol via the interface.

  “Channel capacity calculation” in the present embodiment corresponds to the process of channel estimation performed by the mapping processing unit 443 shown in FIG. 7 and the process of obtaining the value of the channel capacity C from the channel matrix obtained by this channel estimation. Therefore, in a narrow sense, the mapping processing unit 443 and the control unit 5 (and the addition of software routines and data for channel estimation) are one aspect of the “channel capacity calculation unit” according to this embodiment. Applicable. Alternatively, in a broad sense, not only the mapping processing unit 443 but also the preceding block is included, and in terms of software, software routines and data for processing the preceding block are used for channel estimation. What is added to the routine and data corresponds to one aspect of the “channel capacity calculation unit” according to the present embodiment.

On the other hand, regarding the “channel state display unit” according to the present embodiment, a predetermined UI to which channel state display is assigned in advance and a control unit 5 that controls the UI (and a software routine for displaying the channel state) Or data) corresponds to one mode of the “channel state display unit”.
The predetermined UI to which channel state display is assigned in advance is, for example, the display 21, the audio output unit 23, the optical display unit 24, etc., and the control unit 5 as the “display control unit” can be used alone or Channel state display is executed using any combination.

FIG. 8 illustrates a state when transmission channel state display is performed on the display 21.
When the user holds the wireless communication device 1 with his / her hand and presses a transmission channel state display start button or the like in the operation unit 25 (see FIG. 5), for example, the control unit 5 detects this to transmit channel display processing. Starts. The control unit 5 monitors the reception state, and when there is a reception signal, for example, periodically executes processing for obtaining the channel capacity C. That is, the control unit 5 acquires channel information when executing the processing up to the mapping processing unit 443 shown in FIG. 7, and calculates the value of the channel capacity C based on the information. This process is periodically repeated during a period in which the received signal is continuously received. It is not always necessary to perform this periodically, and the channel capacity value may be calculated when the transmission channel state changes significantly.

Each time the value of the channel capacity C is calculated, the control unit 5 as a “display control unit” controls the display on the display 21.
There are several methods that can be used for the control.

The first method is light output control as in the example shown in FIG. In this method, for example, when a predetermined area of the display 21 is assigned to display the status of the device, a level indicator in which several segments as indicated by reference numeral 21A are arranged in a line is displayed in the area. The light emission of the segments that emit light is controlled so that the number of light emitting segments increases as the channel capacity C increases from one to the other. At this time, in consideration of the small number of steps in the 5-level display, the transmission channel state may be displayed more precisely by changing the light emission luminance even within the same segment.
Such display by the level indicator may be OSD (On Screen Display) display superimposed on the background screen. In this case, although the burden of screen composition processing for OSD display is large, there is an advantage that the display area can be made larger than the dedicated display area (device status display area). The OSD process itself is executed by a drive processing IC (not shown) attached to the display 21.

In the first method, as indicated by reference numeral 21B in FIG. 8, the luminance (brightness) of a single segment (screen display resembling a round LED display in this example) is set according to the size of the channel capacity C. You may increase it sequentially.
In addition, as indicated by reference numeral 21C in FIG. 8, a single segment may be switched between, for example, red (transmission channel state is good) and blue (transmission channel state is bad).
These single segment displays may be performed when the segment is provided in the device status display area or when the OSD display is performed.

  In the second method, single segment display in the first method is performed by the optical display unit 24 shown in FIG. This method itself is the same as described above. However, in this case, an LED or the like is used as the light source.

  In the third method, the voice output unit 23 shown in FIG. 5 informs whether communication is possible or not by sound or voice (voice of meaningful sentences). As for the notification by sound, the variation for notifying the level of the transmission channel state is limited in the same way as the optical output, but various contents can be notified by voice.

Although common to the single segment display in the first to third methods, for example, when shifting from red (transmission channel state: good) to blue (transmission channel state: bad), communication is possible but the transmission rate ( The combination of blinking and lighting is set so that the state that is close to the limit of the communicable range becomes red flashing, and the state where communication is possible when the transmission rate is a little higher is blue lighting. It is also possible to adopt other methods.
The first to third methods may be combined.
In addition, when the application operation includes not only the start of transmission channel display by the user but also, for example, activation of a call using a communication function, an Internet connection, or the like, the start timing may be entrusted to the application. That is, when communication is required by the application and a received signal is obtained, processing for displaying the transmission channel state may be automatically started at that time.

<Transmission channel status display control procedure>
Next, the control procedure of the transmission channel state display method will be described.
The transmission channel state display method of this embodiment is
(1) Step 1: A channel capacity value of spatial multiplexing communication at a reception position is calculated from a received signal.
(2) Step 2: compare the calculated channel capacity value with a predetermined threshold;
(3) Step 3: Display the transmission channel state.
(4) Step 4: When the magnitude relationship between the channel capacity value calculated in Step 1 and the threshold is reversed in Step 2, the display of the transmission channel state in Step 3 is changed.
At least four steps.

FIG. 9 is a flowchart showing a procedure of transmission channel state display control taking the method (reference numeral 21A) based on a plurality of segments shown in FIG. 8 as an example.
When the process is started by a user operation, in step ST0, for example, the control unit 5 shown in FIG. 5 gives a threshold value xi to the variable X, and initially sets the threshold value xi as the variable i = 1. Also, the number of comparisons is initialized with a variable n = 1. The number of segments M is determined by the specification, and M = 5 in this example.
As shown in FIG. 9, the display segments are represented by reference numerals S1, S2, 3S, S4, and S5 from the one with the smaller channel capacity C. The threshold value xi is a comparison criterion used for determining the size of the channel capacity C. As shown in the figure, the threshold value xi is given as a comparison criterion for determining whether the segment Si (i = 1 to 5) is turned on or off.

Next, for example, the control unit 5 acquires information on the channel matrix estimated by the mapping processing unit 443 (FIG. 7), and calculates the channel capacity C from the equation of FIG. 1C (step ST1).
In step ST2, the control unit 5 determines n = M. If yes (Y), the process proceeds to the next step ST3, and if no (N), step ST3 is skipped. Since n = 1 at first, step ST3 is executed.

In step ST3, the control unit 5 compares the calculated channel capacity C with a variable xi (threshold value x1). If the channel capacity C is larger than the threshold value x1, the display segment Si (initially S1) is turned on (step ST4), the variable i and variable n are incremented (step ST5), and the process is returned to before step ST2.
For this reason, the routine of steps ST2 to ST5 is repeated until the determination of step ST3 becomes “N”. As a result, a predetermined number of display segments corresponding to the channel capacity C are lit continuously from the display segment S1 side. To do.

Steps ST6 to ST9 are processing (light-off processing) reverse to steps ST2 to ST5. This routine is provided because when the flow returns to step ST1 and the channel capacity C is recalculated, if the value is smaller than the previous calculated value, it is necessary to turn off some LEDs in the segment.
In step ST10, the control unit 5 checks whether or not an end instruction is given by a user operation. If it is ended, the transmission channel state display is all turned off or all the display segments are turned off (step ST11). On the other hand, if the end instruction is not detected, the processing flow is returned to before step ST1, and the calculation of the channel capacity C and the lighting or extinguishing of the segment according to the result are executed.
As described above, an algorithm for periodically calculating the value of the channel capacity C and changing the display of the transmission channel state is realized.

<< Second Embodiment >>
The present embodiment relates to a display method applicable in addition to the transmission channel state display method of the first embodiment. Therefore, FIGS. 5 to 9 used in the first embodiment are similarly applied to this embodiment.

  The display method (fourth method) according to the present embodiment is a method that can be performed in combination with the first to third methods described above. The fourth method is a method that can link the sensitivity of the transmission channel state display according to the application. Hereinafter, the fourth method will be described in detail.

The control unit 5 as a “display control unit” that executes the fourth method detects control information related to the priority of data from the received signal.
As control information, for example, there is access category (AK) information defined in IEEE802.11e. IEEE802.11e AK information is a standard for reclassifying the priority defined by the IEEE802.1D user priority into four AKs and changing the priority at the time of transmission to control QoS (Quality of Service). Based on.

In general, wireless communication is used for devices for various purposes, so it is a low-speed but small-scale device that reduces costs, a device that adopts an advanced method to transmit moving images, and realizes high-speed transmission, There are devices that are not as fast as for video transmission but have a reduced circuit scale. If the user priority is made uniform for these applications, it is impossible to realize a device that transmits / receives high bit rate data or large-capacity data or a communication environment that meets the demands of users.
Therefore, for example, a bandwidth reservation mechanism is considered according to various uses such as home control (security) use, moving picture transmission use, audio transmission use, Internet access use, data transfer use between computers, etc. , QoS information is used for this bandwidth reservation.

  In this embodiment, this AK information is subjected to sensitivity control for transmission channel state display. Here, the “sensitivity control” is a control in which even when the same channel capacity value is detected, the transmission rate and the large-capacity data reception are difficult to switch to the display state indicating communication permission. When the sensitivity control is performed, a transmission channel display that changes in accordance with the use in which the received signal is used is realized depending on whether the application is acquiring data for moving image display or audio output.

The QoS information is communication quality ensuring information to be ensured regarding transmission speed, error rate, time delay, jitter, bandwidth reservation, and the like.
In the IEEE 802.1D QoS standard, the user priority is “background traffic”, “best effort without priority” (Best Effort), “excellent effort (best effort with higher priority)”, “bandwidth guaranteed” Eight are defined as “Controlled Load”, “Video Data”, “Audio Data”, “Network Control”, and “Reserve”. Bandwidth reservation is permitted as QoS, for example, and can be performed by securing a transmission time in advance using a communication method that requires high speed, such as video transmission. When bandwidth reservation is performed, data having a high priority is preferentially processed by a router on the network and the priority for collision avoidance is high, so that necessary transmission time can be secured. In IEEE802.11e, these eight priorities are reclassified into four AKs, and priority control is realized by making a difference in the quality of service provided for each category. As the four AKs, AC_BK for background traffic, AC_BE for best effort, AC_VI for video transmission, and AC_VO for voice are defined. The AK information is stored in the IP header in the IEEE 802.11 data frame.

In this embodiment, since QoS information is used for transmission channel display, it is necessary to detect QoS information by reception processing, and it is detected and demodulated on the wireless reception chip side.
And since the priority of transmission is known from the detected QoS information, the control unit 5 changes the sensitivity to the magnitude of the channel capacity C when changing the transmission channel state display using the information. The sensitivity change can be achieved, for example, by changing a threshold value as a reference for comparing the channel capacity C.

  FIG. 10 shows a transmission channel state display control procedure including a display switching method (fourth method) according to the present embodiment. Since the segment display is complicated, the fourth method is applied to the method (indicated by reference numeral 21C in FIG. 8) for expressing the quality of the transmission channel state by the simplest red and blue color switching in FIG. ing.

When the process is started by a user operation, in step ST01, for example, the control unit 5 shown in FIG. 5 gives a threshold value xi to the variable X, and sets an increase / decrease value ΔXi and polarity of the threshold xi for the other variable Y. To do. The initial value of the increase / decrease value ΔXi is 0.
Next, the control unit 5 detects the priority P (AK information) from the QoS information of the IP header included in the OFDM signal in the received packet, and sets the value and polarity of the increase / decrease value ΔXi according to the priority P. .

Next, for example, the control unit 5 acquires information on the channel matrix estimated by the mapping processing unit 443 (FIG. 7), and calculates the channel capacity C from the equation of FIG. 1C (step ST1).
In subsequent step ST12, the control unit 5 compares the calculated channel capacity C with a variable (xi ± ΔXi). If the channel capacity C is larger than the variable (xi ± ΔXi), the red LED is turned on (step ST13), and if the channel capacity C is less than the variable (xi ± ΔXi), the blue LED is turned on (step ST14).
Thereafter, in step ST10, the control unit 5 checks whether or not an end instruction is given by a user operation, and if it is ended, all the LEDs are turned off (step ST15). On the other hand, if the end instruction is not detected, the process flow is returned to before step ST02, the priority P is acquired, the increase / decrease value ΔXi is changed, the channel capacity C is calculated, and the LED color is changed according to the result. Execute.

As described above, when changing the display of the transmission channel state by periodically calculating the value of the channel capacity C, an algorithm for changing the sensitivity of the LED color change with respect to the channel capacity C based on the acquired priority P is provided. Realized.
If the determination at step ST10 is “N”, the process may be returned to before step ST1. In that case, acquisition of the priority P and increase / decrease setting of the increase / decrease value ΔXi may be performed separately from this routine, for example, by a trigger such as the start of an application.

  A similar mechanism for changing the sensitivity of display switching according to the priority P can be applied to the flowchart of FIG. 9. In this case, the value of the threshold value xi depends on the value and polarity of the increase / decrease value ΔXi. Shift. For this reason, in the case of moving image reception or the like, it is difficult to light the display segment in the full range unless the transmission channel state is so good. At this time, until the display segment lights up near the full range (in the case of FIG. 10, the red LED lights up), the user moves around the location of the wireless communication device to find the optimum point. It becomes easy to arrange.

In FIG. 9 and FIG. 10 described above, the user operation is triggered by the start and end, but the present invention is not limited to this.
Further, guidance for prompting the user to move may be displayed on the display 21.
Further, when the wireless communication device 1 has a position detecting means, the function is used to indicate the value of the channel capacity C for each reception point on a map, and a range suitable for the priority P on the map. May be displayed. In this case, the control unit 5 may control the display 21 such that the higher the priority P, the narrower the reception point range for displaying a good channel state.

Control information other than AK information can also be used.
For example, the user's occupation time is detected by acquiring the time until the MAC address changes from the packet control information, etc., and whether the time is long or short and the data is heavy according to a certain time reference It may be determined whether it is light, and the threshold value may be changed according to the determination.

  According to the first and second embodiments described above, even in a state where a small portable device is not attached to a cradle or the like, that is, in a mobile state where the user is holding it in his / her hand, MIMO in that environment Maximum communication performance can be achieved.

<Modification>
In the first and second embodiments described above, the following various modifications are possible in addition to those described in the above description.
The present invention is based on wireless LAN (IEEE802.11 compliant, Wi-Fi compliant, etc.), WiMAX (World Interoperability for Microwave Access) standardized by IEEE802.16, and MBWA (standardized by IEEE802.20). It can be applied to various wireless communication systems such as Mobile Broadband Wireless Access), next-generation mobile phone systems (so-called 4G systems), and UWB (Ultra Wide Band) using multiple antennas.

The present invention can be suitably applied to a MIMO communication system that spatially multiplexes a plurality of transmission streams, but the order is not limited to two reception antennas, for example, 2 × 2, etc. 3 × The present invention can be similarly applied to a communication system configured with an order of 3 or 4 × 4, which is expected to be the maximum number in IEEE802.11n, or higher.
Further, the application range of the present invention is not limited to a specific wireless communication system that performs spatial multiplexing. For example, the present invention can be similarly applied to other communication systems using a plurality of antennas such as selection diversity, combination diversity, and STBC (Space Time Block Coding).
Various antennas such as quarter-wave monopoles, monopole variants such as helical, meander, capacitive loading, reverse F, etc., microstrip antennas, small antennas using dielectrics, etc. Is applicable.

It is a figure which shows the formula of a 2 * 2 MIMO communication model and channel capacity. It is a distribution map of a transmission matrix. It is a figure which shows the setup used for channel capacity measurement in embodiment of this invention. It is a graph which shows the receiving position dependence of channel capacity in this embodiment. It is a schematic block diagram of the radio | wireless communication apparatus in connection with 1st and 2nd embodiment. It is a schematic block diagram of the RF module in connection with 1st and 2nd embodiment. It is a schematic block diagram in the BB / MAC processing unit according to the first and second embodiments. It is a figure which shows a mode when transmission channel state display is performed on a display in connection with 1st and 2nd embodiment. It is a flowchart which shows the procedure of the transmission channel state display method in connection with 1st Embodiment. It is a flowchart which shows the procedure of the transmission channel state display method in connection with 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication apparatus, 2 ... Housing, 2A ... Antenna cover, 4 ... RF module, 5 ... Control part, 21 ... Display, 22 ... Battery, 23 ... Audio | voice output part, 24 ... Light display part, 25 ... Operation part , 41_1, etc .... Duplexer, 42 ... Motor unit, 42_1, etc .... RF reception processing unit, 43_1, etc .... RF transmission processing unit, 44 ... BB / MAC processing unit, 441 ... Pre-processing unit, 442 ... FFT unit, 443 ... Mapping processing , 444 ... post-processing unit, Tr1, Tr2 ... receiving antenna

Claims (7)

A wireless communication device capable of spatial multiplexing communication between a plurality of transmitting antennas and a plurality of receiving antennas,
A channel capacity calculation unit that calculates a channel capacity value of a transmission path at a reception position of the wireless communication device from a received signal;
A channel state display unit for displaying a transmission channel state according to the calculated channel capacity value;
Control information related to the priority of data is detected from the received signal. Based on the detected control information, the higher the priority, the more sensitive the display change of the transmission channel state to the magnitude of the channel capacity value. A display control unit for controlling the channel state display unit so as to be dull ;
A wireless communication device. A wireless communication device capable of spatial multiplexing communication between a plurality of transmitting antennas and a plurality of receiving antennas,
A channel capacity calculation unit that calculates a channel capacity value of a transmission path at a reception position of the wireless communication device from a received signal;
A channel state display unit for displaying a transmission channel state according to the calculated channel capacity value;
From the received signal, control information regarding the priority of data is detected, and based on the detected control information, the higher the priority, the narrower the range of the reception position for displaying a good channel state. A display control unit for controlling the channel state display unit ;
A wireless communication device. The display control unit
The calculated channel capacity value is compared with a predetermined threshold, and when the magnitude relationship between the calculated channel capacity value and the threshold is reversed, the display of the transmission channel state is changed,
The higher the priority based on the detected control information, the wireless communication apparatus according to claim 1 or 2 to increase the value of the threshold. The wireless communication apparatus according to any one of claims 1 to 3, wherein the channel state display unit is configured to be able to display the transmission channel state in multiple stages. The wireless communication device according to any one of claims 1 to 3, wherein the channel state display unit is configured to be able to display whether the transmission channel state is good or bad. On the receiving side of the spatial multiplexing communication performed between the plurality of transmission antennas and the plurality of reception antennas, calculating a channel capacity value of the spatial multiplexing communication at the reception position from the received signal;
Comparing the calculated channel capacity value with a predetermined threshold;
Displaying a transmission channel state;
When the magnitude relationship between the calculated channel capacity value and the threshold value is reversed, the display of the transmission channel state is changed, and control information related to the priority of data is detected from the received signal when the display is changed. Then, based on the detected control information, the higher the priority, the lower the sensitivity of the display change of the transmission channel state to the size of the channel capacity value ;
A transmission channel state display method including: On the receiving side of the spatial multiplexing communication performed between the plurality of transmission antennas and the plurality of reception antennas, calculating a channel capacity value of the spatial multiplexing communication at the reception position from the received signal;
Comparing the calculated channel capacity value with a predetermined threshold;
Displaying a transmission channel state;
When the magnitude relationship between the calculated channel capacity value and the threshold is reversed, the display of the transmission channel state is changed, and when the display is changed, control information related to the priority of data is detected from the received signal, Based on the detected control information, the higher the priority, the narrower the range of the reception position for displaying a good channel state;
A transmission channel state display method including:

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