JP2012186701A - Radio communication terminal - Google Patents

Abstract

In a wireless communication terminal that performs wireless communication in a plurality of wireless communication bands, a wireless communication terminal that can secure low power consumption and stable communication is provided.
First radio communication means 10 capable of communicating in a predetermined range using radio waves in a predetermined band, and first radio communication means using radio waves in a band different from first radio communication means 10. A second wireless communication comprising a demodulation means 22 for demodulating received wireless data and a calculation means 23 for calculating a value of a reception state from a signal obtained by the demodulation processing. Means 20, selection means 31 for selecting which wireless communication means to use preferentially, and a reception state for comparing the reception state value calculated by calculation means 23 with a threshold value based on the selection result by selection means 31 Comparing means 30 and determining means 40 for determining which communication means to communicate based on the comparison result are provided.
[Selection] Figure 1

Description

  The present invention relates to a wireless communication terminal that performs wireless communication, and more particularly to a wireless LAN terminal.

IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard wireless LAN is convenient not only for companies and homes but also for stations, airports, hotels, etc. It has spread to restaurants such as cafes.
In recent years, “IEEE802.11n” (hereinafter referred to as “11n”), whose theoretical maximum transmission speed reaches 600 Mbps, has been standardized and commercialized, and there is a need for wireless communication that enables higher capacity and higher speed transmission. It is increasing.
Therefore, the working group of the IEEE 802 committee is studying standardization of next-generation wireless LANs such as IEEE 802.11ac (hereinafter referred to as 11ac) and IEEE 802.11ad (hereinafter referred to as 11ad).

11ac is compatible with 11n, the theoretical maximum transmission rate is 3 Gbps or more, and the frequency band used for communication is the 5 GHz band.
11ad has a theoretical maximum transmission rate of 6 Gbps or more, and a frequency band used for communication is a 60 GHz band.
11ac, which uses the 5 GHz band, can communicate outside the line of sight, but 11ad communicates in the millimeter wave (60 GHz) band, which has strong radio wave straightness. End up. On the other hand, 11ad has an advantage that the data transmission speed can be easily increased.
Therefore, it is expected that both high-speed wireless communication and wide-range connectivity can be ensured by using 11ad having a high transmission rate and 11ac that can secure wide-range connectivity.

FIG. 6 is a diagram illustrating an example of a wireless system in which 11ac and 11ad are combined to form a BSS (Basic Service Set) / PBSS (Personal Basic Service Set).
The BSS is a network composed of one access point (AP) and a subordinate wireless LAN client in radio waves of the access point in the wireless LAN infrastructure mode.
PBSS is a network (ad hoc mode) in which wireless LAN clients communicate directly with each other without using an access point.
In FIG. 6, the set top boxes 2 and 5, the televisions 3 and 6, and the wireless communication terminal 4 each have a function as a wireless LAN client.
In addition, these devices can communicate with neighboring devices using 11ad in ad hoc mode, and can communicate with the access point 1 using 11ac.

In FIG. 6, the access point 1 forms a BSS by 11ac (infrastructure mode) using a 5 GHz band within the communication range 1A. Therefore, as shown by the communication range 1A, communication is possible in most places in the house, and a wide range of connectivity can be secured.
The access point 1 is connected to the set top box 2 and the set top box 5 in the infrastructure mode.
The set-top box 2 forms a PBSS using 11ad in the communication range 2A, and can communicate with the television 3 and the wireless communication terminal 4 in the communication range 2A in the ad hoc mode.
That is, the set-top box 2 communicates with the access point 1 in the 11ac at the infrastructure mode, and communicates with the television 3 and the wireless communication terminal 4 in the ad hoc mode using the 11ad using the 60 GHz band. Is going.
In 11ad, the set top box 2 communicates in a narrow communication range in which radio waves reach only in the room as indicated by the communication range 2A. However, since 11ad is used, the set top box 2 and the set top box 2 The communication between the television 3 and the wireless communication terminal 4 can perform a large-capacity and high-speed transmission compared to the communication by 11ac.
Similarly, the set-top box 5 can form a PBSS using 11ad in the communication range 5A, and can communicate with the television 6 in the communication range 5A in the ad hoc mode.

By the way, it plays a central role in a terminal (station) that forms an ad hoc network using 11ad while communicating as a terminal (station) connected to the access point 1 using 11ac, such as the set top box 2. A wireless communication terminal that performs communication is called a PCP (PBSS Central Point) in the 11ad standard (IEEE P802.11ad / D0.1) currently under consideration.
The set-top box 5 is also a PCP like the set-top box 2 and communicates in the infrastructure mode with the access point 1 by 11ac, while ad hoc using 11ad in the 60 GHz band with the TV 6 in the communication range 5A. Mode communication.

FIG. 7 is a diagram when the wireless communication terminal 4 in FIG. 6 moves in the direction of the arrow.
In FIG. 7, the wireless communication terminal 4 communicates with the set top box 2 using 11ad in the communication range 2A. However, in FIG. 7, the wireless communication terminal 4 moves out of the communication range 2A. Switched to 1. That is, the wireless communication terminal 4 has changed the communication band from 11ad that performs communication in the 60 GHz band to 11ac that performs communication in the 5 GHz band.
By the way, in the 11ad working group of the IEEE 802 committee, standardization is being studied as a use case in which uncompressed HD (High Definition) video is transmitted.
For example, when transmitting HD video (1,080p, 24 bits / pixel, 60 frames / second) via wireless communication, the speed is 3 Gbit / second or more and the delay time is within 10 milliseconds. Become.

That is, when the wireless communication terminal 4 moves during transmission of HD video and changes the communication method from 11ad that performs communication in the 60 GHz band to 11ac that performs communication in the 5 GHz band, it takes 10 milliseconds or more to change the communication method. If this time is taken, there is a problem that the HD video displayed on the wireless communication terminal 4 is interrupted.
Therefore, when the communication method is changed from 11ad that performs communication in the 60 GHz band to 11ac that performs communication in the 5 GHz band, it is necessary to switch at high speed.
In general, the communication range of the 60 GHz band wireless communication that is a millimeter wave is a sufficiently narrow communication range compared to the wireless communication range of the 5 GHz band. Therefore, the communication range of 60 GHz band radio communication is often located within the radio communication range of 5 GHz band.
Therefore, switching from 11ad that performs communication in the 60 GHz band to 11ac that performs communication in the 5 GHz band is performed after the 11ad that performs communication in the 60 GHz band is disconnected due to being out of the communication range.

However, the boundary of the communication range, that is, the boundary line between the 11ad communication area where communication is performed in the 60 GHz band and the impossible area, changes every moment depending on the surrounding environment such as the influence of fading and the interference wave of the adjacent channel. It is difficult to decide uniquely.
If the boundary of the communication range is mistaken, communication from 60 GHz band to communication in 5 GHz band, further communication from 5 GHz band to communication in 60 GHz band, and communication from 60 GHz band to communication in 5 GHz band again. As described above, the communication band is frequently switched.
Since switching of the communication band requires reconnection processing in each communication band, frequent switching of the communication band becomes a load of data communication.
In particular, when it is necessary to switch the communication band at high speed, such as during HD video transmission, the possibility of interrupting the transmission is increased, resulting in a problem that the stability of communication is impaired. In addition, since wireless data is transmitted and received for reconnection processing in each communication band, a problem of increased power consumption is also caused.
For this reason, it is desirable to start / switch communication within an optimal 60 GHz band communication range that does not cause frequent switching of the communication band.
This is not only a problem of 11ac, but the same problem occurs when using a communication method capable of wide-range communication like 11ac, such as IEEE802.11a / b / g / n.

Also, depending on the application (data transfer, HD video transmission, etc.), the allowable time varies even if communication is interrupted. For example, if HD video (1,080p, 24 bits / pixel, 60 frames / second) is interrupted for 10 milliseconds, HD video will be interrupted, but if FTP (File Transfer Protocol) data transfer is in progress Even if communication is interrupted by about 50 mm, the user will not notice at all.
Furthermore, 11ad can communicate at a higher capacity and at a higher speed than 11ac. For example, during FTP data transfer, even if the communication band is slightly switched, communication is performed with priority using 11ad. It is preferable to finish the process earlier because power consumption can be reduced.
On the other hand, during transmission of HD video, it can be said that frequent switching of communication bands should not occur.
As described above, the optimal communication range of the 60 GHz band for starting / switching communication varies depending on the application.
In 11ad, since the communication range is narrow, the necessity of beam forming technology increases.
In the beam forming technique, for example, by communicating radio waves from the set top box 2 in a specific direction, it becomes possible to communicate with a station (radio communication terminal 4, television 3, etc.) located farther away.

FIG. 8 is a diagram showing a communication range when beam forming is performed and when beam forming is not performed.
When the beam forming technique is used, the radio wave reaches farther, and as shown in FIG. 8, the radio wave reaches the radio communication terminal 4 at a far position.
However, in order to use the beam forming technique, the transmitter side transmits a signal called a training signal, calculates information about the transmission path such as the amplitude and phase of the training signal received at the receiver side, and feeds back to the transmitter side. There must be. Therefore, there is a problem that it takes time to start beamforming communication.
FIG. 9 is a diagram illustrating a case where the wireless communication terminal 4 in FIG. 8 moves outside the beamforming communication range.
As shown in FIG. 9, once outside the beamforming communication range, the transmitter side again has to transmit a training signal and receive feedback of information regarding the transmission path, which further takes time. Therefore, when the communication band is frequently switched when using the beam forming technique, more wireless data must be transmitted and received for reconnection than when the beam forming technique is not used. This further increases the possibility of interrupting transmission, impairs the stability of communication, and causes the problem of increased power consumption.

As described above, particularly when the beam forming technique is used, it is desired to start / switch communication in the optimal communication range of the 60 GHz band where frequent switching of the communication band does not occur.
As a technique for appropriately switching between communication bands and communication methods in a wireless communication apparatus that performs communication by switching between different wireless communication bands or communication methods (ad hoc mode / infrastructure mode), Patent Document 1 discloses reception. There has been disclosed a wireless communication apparatus that can activate an ad hoc mode wireless communication unit only when necessary by starting or stopping the ad hoc mode wireless communication unit according to a change in electric field strength.
As a technology for switching between different access points at high speed, Patent Document 2 discloses a wireless LAN that performs roaming to the wireless signal strength of an adjacent access point having the maximum wireless signal strength.

However, Patent Document 1 has a problem in that the reception environment cannot be properly grasped because the reception electric field strength is greatly affected by the surrounding environment such as fading and adjacent channel interference waves. In addition, there is a problem that it is not considered that when the maximum transmission speed and the communication range are different between the ad hoc mode and the infrastructure mode, the optimum time for starting or stopping the ad hoc mode wireless communication unit is changed.
Further, in Patent Document 2, there is a problem that the reception environment cannot be properly grasped because the wireless signal strength is greatly influenced by surrounding environments such as fading and adjacent channel interference waves. In addition, there is a problem that it is not considered that the optimum access point to be connected changes when the maximum transmission speed and the communication range are different between adjacent access points.
As described above, in the conventional wireless communication terminal, the reception electric field strength is used for grasping the communication range, and therefore the reception environment cannot be grasped properly, and the access point or the wireless communication terminal having a different transmission speed or communication range. In this case, there is a problem that the communication band is frequently switched, the stability of communication is lost, and unnecessary power consumption occurs.
The present invention has been made in view of such problems, and in a wireless communication terminal that performs wireless communication in a plurality of wireless communication bands, low power consumption is achieved by appropriately switching the wireless communication band according to the parameters indicating the priority of the wireless communication band and the reception state. It is another object of the present invention to provide a wireless communication terminal capable of ensuring communication stability.

In order to solve the above problems, the present invention provides a wireless communication terminal comprising a plurality of wireless communication means and capable of transmitting and receiving wireless data by a communication method using different wireless communication bands. The first wireless communication means for performing communication in the infrastructure mode, and a signal obtained by performing communication within a narrow range using a higher band than the first wireless communication means and demodulating the received wireless data A second wireless communication unit that includes a calculation unit that calculates a reception state of the wireless data, and performs communication using a communication method using a wireless communication band different from the first wireless communication unit; and the first wireless communication unit Selection means for preferentially using the second wireless communication means, the reception state of the wireless data calculated by the calculation means, and the selection means selected by the selection means. A reception state comparison unit that compares a reference reception state set for the communication method used by the wireless communication unit, and the first wireless communication unit and the second wireless unit based on a comparison result by the reception state comparison unit. Determining means for determining which of the communication means is used to transmit and receive wireless data.
According to the present invention, by grasping the reception state and appropriately switching the wireless communication band, it is possible to ensure low power consumption and communication stability.

According to a second aspect of the present invention, the determination unit is configured such that the reception state of the wireless data calculated by the calculation unit is based on a reference reception state set for a communication method used by the wireless communication unit selected by the selection unit. If the wireless data is good, the wireless data is transmitted and received by the second wireless communication means, and the reception state of the wireless data calculated by the calculation means is used by the wireless communication means selected by the selection means If it is lower than the reference reception state set for, it is determined that wireless data transmission / reception is performed by the first wireless communication means.
According to the present invention, by grasping the reception state and appropriately switching the wireless communication band, it is possible to ensure low power consumption and communication stability.

The invention according to claim 3 is a wireless communication terminal comprising a plurality of wireless communication means and capable of transmitting and receiving wireless data by a communication method using different wireless communication bands, wherein the first wireless performs communication in a wide infrastructure mode. A calculation for performing communication within a narrow range using a higher bandwidth than the first wireless communication means and calculating a reception state of the wireless data from a signal obtained by demodulating the received wireless data. And a second wireless communication means for performing communication using a communication method using a wireless communication band different from that of the first wireless communication means, and a detection means for detecting the reception strength of the wireless data, Selection means for selecting which of the first wireless communication means and the second wireless communication means is used preferentially, the reception state calculated by the calculation means, and selection by the selection means A reception state comparison unit for comparing a reference reception state set for the communication method used by the wireless communication unit, the reception intensity calculated by the calculation unit, and the wireless communication unit selected by the selection unit Based on the comparison results by the reception state comparison means and the reception strength comparison means, and the first wireless communication means and the second wireless communication means. Determining means for determining which of the wireless communication means is used to transmit / receive wireless data.
According to the present invention, in addition to the reception state, by grasping the reception intensity and switching the wireless communication band more appropriately, low power consumption and communication stability can be ensured.

According to a fourth aspect of the present invention, the determination unit is configured such that the reception state of the wireless data calculated by the calculation unit is based on a reference reception state set for a communication method used by the wireless communication unit selected by the selection unit. The reception strength of the wireless data detected by the detection means is higher than the reference reception strength set for the communication method used by the wireless communication means selected by the selection means, the second It is determined that wireless data is transmitted / received by wireless communication means.
According to the present invention, in addition to the reception state, by grasping the reception intensity and switching the wireless communication band more appropriately, low power consumption and communication stability can be ensured.
According to a fifth aspect of the present invention, the calculating means receives a modulation accuracy value obtained from an error vector that is a difference between a reception vector and a determination vector in a signal obtained by demodulating received radio data. It is calculated as a state.

The invention according to claim 6 is characterized by comprising setting means for setting which of the first wireless communication means and the second wireless communication means is selected for the selection means.
According to the present invention, it is possible to arbitrarily set the priority of the wireless communication means, and by switching the wireless communication band more appropriately, low power consumption and communication stability can be ensured.
According to a seventh aspect of the present invention, the selecting means detects whether or not beam forming is used for transmission / reception of wireless data using the second wireless communication means, and based on the detection result, the selection means and the first wireless communication means Which of the second wireless communication means is to be prioritized is determined.
According to the present invention, it is possible to secure low power consumption and stable communication by appropriately switching the wireless communication band even when using beamforming that takes time to switch wireless means.

  According to the present invention, in a wireless communication terminal that performs wireless communication in a plurality of wireless communication bands, by appropriately switching the wireless communication band according to the priority of the wireless communication band and the parameter indicating the reception state, with low power consumption, In addition, it is possible to provide a wireless communication terminal that can ensure the stability of communication.

The figure which shows the structural example of the wireless LAN terminal which concerns on embodiment of the wireless communication terminal of this invention. The figure which shows the polar coordinate in a QPSK modulation system. The figure which shows the judgment flow of the radio | wireless communication means used in the wireless LAN terminal shown in FIG. The figure which shows the structure of the wireless LAN terminal which concerns on another embodiment of this invention. The figure which shows the judgment flow of the radio | wireless communication means used in the wireless LAN terminal shown in FIG. The figure which shows an example of the radio | wireless system which forms BSS / PBSS combining IEEE802.11ac and IEEE802.11ad. The figure when the radio | wireless communication terminal in FIG. 6 moves to the direction of the arrow. The figure which showed the communication range with and without beam forming. The figure which shows the case where the radio | wireless communication terminal in FIG. 8 moves out of the communication range of beam forming.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a wireless LAN terminal according to an embodiment of a wireless communication terminal of the present invention.
Note that the communication environment in which the present wireless LAN terminal is used is the environment as shown in FIG. 6 and will be described using the wireless communication terminal 4 in FIG. 6 as an example of the present wireless LAN terminal.
In FIG. 1, only functional units related to the present invention are shown, and other functional units are omitted.
This wireless LAN terminal has a first frequency band 10 different from the first frequency band (wireless communication band) in the first frequency band and the first wireless communication means 10 for performing communication by the first wireless communication method. In a band (wireless communication band), a second wireless communication unit 20 for performing communication by a second wireless communication system different from the first wireless communication system is provided.

Here, the first wireless communication unit 10 performs communication by the above-described IEEE802.11ac (11ac: first wireless communication method) in a frequency band of the 5 GHz band (first wireless communication band), for example, and performs the second wireless communication. The communication unit 20 performs communication by the above-described IEEE802.11ad (11ad: second wireless communication method) in a frequency band (second wireless communication band) of, for example, 60 GHz band.
Of course, the combination of frequency bands / communication methods used in both wireless communication means is not limited to these. For example, in the first wireless communication means, IEEE800.211b / g using 2.4 GHz band is used. Applicable when used.
In FIG. 1, the first wireless communication unit 10 includes an RF unit 11 that receives a radio signal modulated based on 11ac, and a demodulation unit 12 that performs demodulation processing on the radio signal received by the RF unit 11. ing.
The second radio communication unit 20 includes an RF unit 21 that receives a radio signal modulated based on 11ad, a demodulation unit 22 that performs a demodulation process on the radio signal received by the RF unit 21, and a demodulation unit 22 Calculating means 23 for calculating a reception state parameter indicating a radio propagation characteristic from a signal obtained by the demodulation processing according to FIG.

The wireless LAN terminal of the present invention further includes a selection means 31 for selecting which of the first wireless communication means 10 and the second wireless communication means 20 is used preferentially, and the reception state parameter calculated by the calculation means 23, The first wireless communication unit 10 and the second wireless communication are based on the reception state comparison unit 30 that compares with a predetermined threshold (reference reception state) based on the selection result by the selection unit 31 and the comparison result in the reception state comparison unit 30. Determining means 40 for determining which wireless communication means of the means 20 is to transmit and receive wireless data.
Note that the calculation unit 23 can calculate a modulation accuracy value as an example of a reception state parameter from an error vector that is a difference between the reception vector and the determination vector, for example (modulation accuracy calculation unit).
Here, the reception state comparison unit 30, the selection unit 31, and the determination unit 40 are in an upper layer representing the data link layer and the application layer, but may be in the physical layer as a matter of course.
In addition, although the physical layer which is layer 1 and a part of the upper layer are separated into the first wireless communication unit 10 and the second wireless communication unit 20, a part such as an antenna may be shared.

・・・式（１）
ここで、
Ｎ_f：算出に用いるフレーム総数
ｉ：フレームインデックス
ｋ：キャリアインデックス
ｊ：シンボルインデックス
Ｎ_STM：算出に用いるシンボル総数
Ｎ_ST：算出に用いるサブキャリア総数
Ｉ₀、Ｑ₀：理想シンボルのポイント
Ｐ₀：理想シンボルの平均パワー
となる。
変調精度は、受信信号に式（１）をそのまま使用して算出してもよいし、算出結果をデシベルに換算しても良いし、測定シンボルのＤＣオフセットや周波数オフセット等を補正した後の受信信号を用いて式（１）により算出しても良い。また、変調精度は、任意のフレーム数、シンボル数、キャリア数で平均を取って、用いてもよい。
また、図１の復調手段１２、２２はＩチャネル、Ｑチャネルごとに信号成分を判定するデマップ処理を行う。 FIG. 2 is a diagram showing polar coordinates in the QPSK modulation method used in 11ac, 11ad, and the like.
The error vector used for calculating the modulation accuracy in the calculating means 23 is a vector difference between an ideal symbol that is a determination vector and a measurement symbol that is a reception vector, and is a complex quantity including an amplitude component and a phase component.
In other words, the error vector can be said to be residual noise and distortion remaining after taking the ideal symbol.
The modulation accuracy is obtained by the following equation (1).

... Formula (1)
here,
N _f : Total number of frames used for calculation i: Frame index k: Carrier index j: Symbol index N _STM : Total number of symbols used for calculation N _ST : Total number of subcarriers used for calculation I ₀ , Q ₀ : Point P _{0 of} ideal symbol: The average power of the ideal symbol.
The modulation accuracy may be calculated using the equation (1) as it is for the received signal, the calculation result may be converted to decibels, or reception after correcting the DC offset, frequency offset, etc. of the measurement symbol. You may calculate by Formula (1) using a signal. The modulation accuracy may be averaged using an arbitrary number of frames, symbols, and carriers.
Further, the demodulating means 12 and 22 in FIG. 1 perform a demapping process for determining a signal component for each I channel and Q channel.

FIG. 3 is a diagram showing a determination flow of wireless communication means used in the wireless LAN terminal shown in FIG.
It is assumed that the wireless LAN terminal is currently performing communication based on 11ad that performs communication in the 60 GHz band using the second wireless communication unit 20.
The wireless communication terminal confirms whether or not the selection means 31 has been selected by the second wireless communication means 20 so that 11ad performing communication in the 60 GHz band is prioritized (step S101).
If 11ad that performs communication in the 60 GHz band is selected to be given priority (Yes in step S101), the modulation accuracy threshold (reference reception state) X is set to −7 dB (step S102).
When 11ac that performs communication in the 5 GHz band using the first wireless communication unit 10 is selected to be given priority (No in step S101), the modulation accuracy threshold value X is set to −15 dB (step S106). .

Here, it is assumed that 11ad that performs communication in the 60 GHz band is selected in the selection unit 31 so that the priority is selected, and the modulation accuracy threshold value X is set to −7 dB.
The calculation means 23 calculates an error vector (difference between the reception vector and the determination vector) as a modulation accuracy value from the signal obtained by the demodulation processing by the demodulation means 22 (step S103). Here, it is assumed that the calculation result of the error vector is −8 dB. In this case, since the calculation result (−8 dB) of the error vector as a result of the comparison by the reception state comparison unit 30 is equal to or less than the modulation accuracy threshold value X (−7 dB) (Yes in step S104), the determination unit 40 performs communication in the 60 GHz band. It is determined that the communication is continued in 11ad (step S105), and the wireless communication band and the communication method are not switched.
On the contrary, when the calculation result of the error vector by the calculation unit 23 is equal to or greater than the modulation accuracy threshold value X (No in step S104), the determination unit 40 determines that 11ac is used for communication in the 5 GHz band (step S107). ) The band / wireless communication method is switched (step S108).
By configuring as described above, in a wireless LAN terminal that performs wireless communication using a plurality of wireless communication bands and communication methods, the wireless communication band can be appropriately switched according to the parameters indicating the priority of the wireless communication band and the reception state. Therefore, low power consumption and stable communication can be ensured.
Also, the modulation accuracy value can be used as a reception state parameter, and by appropriately switching the wireless communication band, low power consumption and communication stability can be ensured.

FIG. 4 is a diagram showing a configuration of a wireless LAN terminal according to another embodiment of the present invention.
4, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
The first wireless communication unit 10 includes, for example, an RF unit 11 that receives a radio signal modulated based on 11ac, and a demodulation unit 12 that performs a demodulation process on the radio signal received by the RF unit 11.
The second radio communication unit 20 includes an RF unit 21 that receives a radio signal modulated based on, for example, 11ad, a demodulation unit 22 that performs a demodulation process on the radio signal received by the RF unit 21, and a demodulation unit 22 Calculating means 23 for calculating a reception state parameter indicating a radio propagation characteristic from a signal obtained by the demodulation processing by, and a detection means 24 for detecting a reception level obtained by the demodulation processing by the demodulation means 22.

The wireless LAN terminal of the present invention further includes a selection means 31 for selecting which of the first wireless communication means 10 and the second wireless communication means 20 to use preferentially, and the reception calculated by the calculation means 23. The reception state comparison unit 30 that compares the state parameter with a predetermined threshold value based on the selection result by the selection unit 31, and the reception intensity detected by the detection unit 24 is compared with a predetermined threshold value based on the selection result by the selection unit 31. Based on the comparison result by the reception strength comparison unit 32 and the reception state comparison unit 30 and the comparison result by the reception strength comparison unit 32, either the first wireless communication unit 10 or the second wireless communication unit 20 transmits / receives wireless data. Determination means 40 for determining whether or not.
Here, the reception strength comparison unit 32, the reception state comparison unit 30, the selection unit 31, and the determination unit 40 are in an upper layer representing the data link layer and the application layer, but may of course be in the physical layer.
In addition, the physical layer which is layer 1 and a part of the upper layer are divided into first wireless communication means 10 and second wireless communication means 20.

FIG. 5 is a diagram showing a determination flow of wireless communication means used in the wireless LAN terminal shown in FIG.
It is assumed that the wireless LAN terminal is currently performing communication using 11ad that performs communication in the 60 GHz band by the second wireless communication unit 20. The wireless LAN terminal confirms whether or not the selection means 31 has been selected by the second wireless communication means 20 so as to give priority to 11ad that performs communication in the 60 GHz band (step S201).
If 11ad that performs communication in the 60 GHz band is selected to be prioritized (Yes in step S201), the modulation accuracy threshold value (reference reception state) X is set to -7 dB, and the reception level threshold value (reference reception intensity) Y Is set to −60 dB (step S202).
On the other hand, when 11ac that performs communication in the 5 GHz band is selected by the first wireless communication means 10, the modulation accuracy threshold value X is set to -15 dB, and the reception level threshold value Y is set to -50 dB. (Step S207).

Here, it is assumed that 11ad that performs communication in the 60 GHz band is selected to be given priority, the modulation accuracy threshold value X is set to -7 dB, and the reception level threshold value Y is set to -60 dB.
As in the case of FIG. 1, the calculation unit 23 calculates an error vector, which is a difference between the reception vector and the determination vector, from the signal obtained by the demodulation process by the demodulation unit 22. Here, it is assumed that the calculation result of the error vector is −8 dB.
Further, the detection means 24 calculates the reception level from the reception intensity detection level (step S203).
The reception level may be calculated using RSSI (Receive Signal Strength Indication) or using power calculated from the I channel and Q channel.
Here, it is assumed that the reception level calculation result is −62 dB.
As a result of comparison by the reception state comparison means 30, the error vector calculation result (−8 dB) is equal to or less than the modulation accuracy threshold value X (−7 dB). However, as a result of comparison by the reception intensity comparison means 32, a reception level calculation result (− 62) Since dB is not equal to or greater than the reception level threshold Y (−60 dB) (No in step S204), the determination unit 40 determines that communication is performed using 11ac that performs communication in the 5 GHz band (step S207). Switching to 11ac for communication is performed (step S208).

Conversely, if the error vector calculation result is equal to or lower than the modulation accuracy threshold value X and the reception level is equal to or higher than the reception level threshold value Y (step S204), the wireless communication band / wireless communication method is not switched, and the 60 GHz band is left as it is. Communication is performed at 11ad that performs communication in the wireless communication band.
According to the present invention, in addition to the reception state, the reception intensity can be grasped in detail, and the radio communication band can be switched more appropriately to ensure low power consumption and communication stability. .
In the configuration shown in FIGS. 1 and 4, the selection unit 31 detects whether the first wireless communication unit 10 or the second wireless communication unit 20 is selected by the user using the wireless LAN terminal, The judging means 40 uses the threshold value based on the selection result by the selection means 31 and the comparison result by the reception state comparison means 30 (in the case of FIG. 1) or the comparison result by the reception state comparison means 30 and the reception intensity comparison means 32 (in the case of FIG. 4). ) And the first wireless communication means 10 or the second wireless communication means 20 to determine whether to transmit / receive wireless data.
That is, this is a case where a user who uses a wireless LAN terminal sets a preferred wireless communication means using a setting tool (setting means).
For example, when performing HD video transmission that does not require frequent switching of the communication band, the first wireless communication unit 10 is set to give priority to 11ac that performs communication in the 5 GHz band.

In addition, when FTP data transfer for which high speed is to be prioritized is performed without any problem even if the communication band is frequently switched, the second wireless communication unit 20 is set to give priority to 11ad that performs communication in the 60 GHz band.
Here, the user has directly set using the setting tool. For example, when an application for displaying HD video is activated, the first wireless communication means 10 is automatically preferentially selected. The application may set it automatically.
By configuring in this way, the priority of the wireless communication means can be set by the user, the wireless communication band can be switched more appropriately, low power consumption and communication stability can be ensured.
Further, the selection unit 31 detects whether or not beam forming is used for transmission / reception of wireless data using the second wireless communication unit 20, and the determination unit 40 determines whether the selection result in the selection unit 31 and the reception state comparison unit 30 Based on the comparison result, it may be determined which of the first wireless communication unit 10 and the second wireless communication unit 20 is to transmit and receive wireless data.

When the wireless communication terminal 4 performs transmission / reception of wireless data using the beam forming technique, it takes time to acquire information on the transmission path at the time of reconnection, so that the communication band is not frequently switched. The first wireless communication means 10 is selected to give priority to 11ac that performs communication in the 5 GHz band. When the wireless communication terminal 4 does not use the beam forming technique, the second wireless communication unit 20 is selected to give priority to 11ad that performs communication in the 60 GHz band.
With this configuration, even when using beamforming that takes time to switch wireless communication means, it is possible to ensure low power consumption and stable communication by appropriately switching the wireless communication band. .

1 access point, 1A communication range, 2 set top box, 2A communication range, 3 television, 4 wireless communication terminal, 5 set top box, 5A communication range, 6 television, 10 wireless communication means, 11 RF unit, 12 demodulation means, 20 wireless communication means, 21 RF section, 22 demodulation means, 23 calculation means, 24 detection means, 30 reception state comparison means, 31 selection means, 32 reception intensity comparison means, 40 determination means

JP 2007-288722 A JP 2001-094572 A

Claims (7)

A wireless communication terminal comprising a plurality of wireless communication means and capable of transmitting and receiving wireless data by a communication method using different wireless communication bands,
A first wireless communication means for communicating in a wide infrastructure mode;
Communication means for performing communication within a narrow range using a higher band than the first wireless communication means, and calculating means for calculating a reception state of the wireless data from a signal obtained by demodulating the received wireless data, Second wireless communication means for performing communication using a communication method using a wireless communication band different from the first wireless communication means;
Selection means for selecting which of the first wireless communication means and the second wireless communication means is used preferentially;
A reception state comparison unit that compares the reception state of the wireless data calculated by the calculation unit with a reference reception state set for a communication method used by the wireless communication unit selected by the selection unit;
A determination unit that determines which of the first wireless communication unit and the second wireless communication unit is used to transmit and receive wireless data based on a comparison result by the reception state comparison unit;
A wireless communication terminal comprising: The determination means includes
If the reception state of the wireless data calculated by the calculation unit is better than the reference reception state set for the communication method used by the wireless communication unit selected by the selection unit, the second wireless communication Send and receive wireless data by means,
When the reception state of the wireless data calculated by the calculation unit is lower than the reference reception state set for the communication method used by the wireless communication unit selected by the selection unit, the first wireless communication unit A wireless communication terminal, characterized in that it is determined to perform transmission / reception of wireless data by means of. A wireless communication terminal comprising a plurality of wireless communication means and capable of transmitting and receiving wireless data by a communication method using different wireless communication bands,
A first wireless communication means for communicating in a wide infrastructure mode;
Calculating means for calculating a reception state of the wireless data from a signal obtained by performing communication within a narrow range using a higher band than the first wireless communication means and demodulating the received wireless data; Detection means for detecting the reception intensity of wireless data, and second wireless communication means for performing communication using a communication method using a wireless communication band different from the first wireless communication means,
Selection means for selecting which of the first wireless communication means and the second wireless communication means is used preferentially;
A reception state comparison unit that compares the reception state calculated by the calculation unit with a reference reception state set for a communication method used by the wireless communication unit selected by the selection unit;
A reception strength comparison unit that compares the reception strength calculated by the calculation unit with a reference reception strength set in advance for a communication method used by the wireless communication unit selected by the selection unit;
A determination unit that determines which of the first wireless communication unit and the second wireless communication unit is used to transmit and receive wireless data based on a comparison result by the reception state comparison unit and the reception strength comparison unit;
A wireless communication terminal comprising: The determination means includes
The reception state of the wireless data calculated by the calculation unit is lower than the reference reception state set for the communication method used by the wireless communication unit selected by the selection unit,
The second wireless communication unit when the reception strength of the wireless data detected by the detection unit is higher than a reference reception strength set for the communication method used by the wireless communication unit selected by the selection unit A wireless communication terminal, characterized in that it is determined to perform transmission / reception of wireless data by means of.   The calculation means calculates a modulation accuracy value obtained from an error vector that is a difference between a reception vector and a determination vector in a signal obtained by demodulating received radio data as a reception state of the radio data. The wireless communication terminal according to any one of claims 1 to 4.   6. The setting unit according to claim 1, further comprising a setting unit configured to set which of the first wireless communication unit and the second wireless communication unit is selected for the selection unit. Wireless communication device.   The selection means detects whether beam forming is used for transmission / reception of wireless data using the second wireless communication means, and based on the detection result, the first wireless communication means and the second wireless communication means The wireless communication terminal according to any one of claims 1 to 6, wherein which one is to be prioritized is determined.

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