JP5699569B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a radio communication apparatus, and more particularly, to a radio communication apparatus that constitutes an underlay cognitive radio system in which a secondary user communicates using the same frequency within a range that does not interfere with the primary user in a situation where the primary user exists.

  In order to increase the use efficiency of radio frequency, cognitive radio that recognizes and recognizes the radio wave environment and adaptively determines the frequency and method used for radio communication has been studied. There are two possible methods for cognitive radio. One is that the secondary user (secondary user) who intends to use the frequency secondarily detects the presence of the signal of the primary user (primary user), and the frequency only when the primary user does not exist. It is a method of using. This method may be referred to as overlay cognitive radio. The other method is a method of performing communication using the same frequency in a range in which interference does not occur to the primary user even in a situation where the primary user exists. This method is also referred to as an underlay cognitive radio system.

  Comparing the above two methods, the overlay cognitive radio system does not interfere with the primary user (theoretically), but the frequency utilization efficiency is not so high. If the interference with the primary user can be appropriately suppressed, the underlay cognitive radio system can improve the frequency utilization efficiency.

  In the underlay cognitive radio system, in order to avoid interference with the primary user, it is assumed that channel state information (CSI) is communicated from the primary user. However, this is not realistic because it assumes that the primary user cooperates with the secondary user.

Japanese Patent Laid-Open No. 11-285062

L. B. Le and E. Hossain, “Resource Allocation for spectrum underlay in cognitive radio networks”, IEEE Transactions on Wireless Communications., Vol. 7, no. 12, pp. 5306-5315, 2008.

  If the interference given to the primary user can be estimated, the secondary user can communicate using the same frequency as the primary user within the range of the interference level that the primary user can tolerate. An object of this invention is to provide the technique which can estimate the interference which a secondary user gives to a primary user, without acquiring channel information from a primary user.

In order to solve the above-described problem, the cognitive radio communication apparatus according to the present invention transmits another control message including position information on the first frequency channel and then performs data transmission on the second frequency channel. A cognitive radio communication apparatus that performs data transmission using the second frequency in the presence of an apparatus, wherein the position information acquisition means for acquiring position information, and the other radio communication apparatus includes the first frequency channel. Control channel receiving means for measuring the received power of the control message to be transmitted in the base station, and data transmission at the second frequency based on the position information acquired from the position information acquiring means and the position information included in the control message Interference amount estimating means for estimating the amount of interference exerted on the other wireless communication device at the time, and the second according to the estimated amount of interference It includes a transmission output control means for controlling the transmission output in wave number, the.

  Specific methods for estimating the amount of interference include the following methods, for example.

  As a first method, the interference amount estimation means includes a radio wave propagation model using a distance between transmission and reception and a transmission frequency as parameters, position information acquired from the position information acquisition means, and position information included in the control message. By applying the distance to the other wireless communication device obtained based on the second frequency and the second frequency, the amount of interference exerted on the other wireless communication device when data is transmitted at the second frequency is reduced. presume.

  As a second method, the interference amount estimation means includes a position information acquired from the position information acquisition means in a radio wave propagation model using information on a distance between transmission and reception, a transmission frequency, and information on roads or surrounding buildings as parameters. Applying the distance from the other wireless communication device obtained based on the position information included in the control message, the second frequency, and the road width, road angle, or building height acquired from the map database By doing so, the amount of interference exerted on the other wireless communication apparatus when data is transmitted at the second frequency is estimated. In this case, the wireless communication apparatus needs to include a map database including at least one of a road width, a road angle, and a building height.

  As a third method, the interference amount estimation means includes the other radio obtained based on the received power of the control channel, the position information acquired from the position information acquisition means, and the position information included in the control message. The other wireless communication device when estimating the propagation loss at the first frequency from the distance to the communication device, estimating the propagation loss at the second frequency from the result, and transmitting data at the second frequency Can be estimated.

  As a fourth method, the amount of interference estimation unit includes the position information acquired from the position information acquisition unit and the control message in a radio wave propagation model using the distance between transmission and reception, the transmission frequency, and an unknown parameter as parameters. Determining an unknown parameter in the radio wave propagation model from the distance to the other wireless communication device obtained based on the position information obtained, the first frequency, the transmission power and the reception power of the control message, It is possible to estimate the amount of interference exerted on the other wireless communication device when data is transmitted at the second frequency using the radio wave propagation model. In this case, the wireless communication apparatus needs to store the transmission power of the control message transmitted by the other wireless communication apparatus at the first frequency in advance or obtain the transmission power.

  When the fourth method is employed, the unknown parameter of the radio wave propagation model obtained by the interference amount estimation unit and the distance to the other wireless communication device are transmitted to the second wireless communication device. And receiving the unknown parameter and the distance from the other wireless communication device from the second wireless communication device, and changing the unknown parameter received from the second wireless communication device and the unknown parameter determined by itself to the other The weighted average multiplied by a larger weighting factor is calculated as the distance to the wireless communication device is closer, and the unknown parameter subjected to the weighted average is applied to the radio wave propagation model to transmit the data at the second frequency. The amount of interference exerted on the wireless communication apparatus is estimated.

In the present invention, the antenna has an antenna capable of controlling directivity, and is based on position information included in a control message received from the other wireless communication apparatus and position information obtained from the position information acquisition means. It is also preferable to control the directivity of the antenna so as not to transmit radio waves in the direction in which the other wireless communication device is located.

  The present invention can be understood as a wireless communication apparatus having at least a part of the above means. The present invention can also be understood as a wireless communication method including at least a part of the above processing and a program for executing the method. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

  According to the present invention, it is possible to estimate interference that a secondary user gives to the primary user without obtaining channel information from the primary user, and it is possible to perform communication using the same frequency as long as the primary user is not adversely affected.

It is a figure which shows the functional block of the cognitive radio | wireless communication apparatus concerning this embodiment. It is a flowchart which shows the flow of the transmission output determination process of the cognitive radio | wireless communication apparatus concerning 1st Embodiment. It is a figure explaining the transmission output of the cognitive radio | wireless communication apparatus in 1st Embodiment. It is a flowchart which shows an example of the interference amount estimation process in 1st Embodiment. It is a flowchart which shows another example of the interference amount estimation process in 1st Embodiment. It is a flowchart which shows another example of the interference amount estimation process in 1st Embodiment. It is a flowchart which shows another example of the interference amount estimation process in 1st Embodiment. It is a flowchart which shows the flow of the transmission output determination process of the cognitive radio | wireless communication apparatus concerning 2nd Embodiment. It is a figure explaining the transmission output of the cognitive radio | wireless communication apparatus in 2nd Embodiment. It is a flowchart which shows the flow of the transmission method determination process of the cognitive radio | wireless communication apparatus concerning 3rd Embodiment. It is a figure explaining the transmission method of the cognitive radio | wireless communication apparatus in 3rd Embodiment.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

(First embodiment)
<System overview>
The cognitive radio communication system according to the present embodiment shares a frequency with an existing system (primary user). The cognitive radio communication device (secondary user) uses the same frequency as the primary user and performs communication with a transmission output that does not interfere with the primary user. That is, the cognitive radio communication system according to the present embodiment is a so-called underlay type cognitive system.

Here, description will be made assuming that both the existing system and the cognitive system are vehicle-to-vehicle communication systems, but both the existing system and the cognitive system may be wireless communication systems of any form.

The existing system employs the CSMA / CA method, which is a multiple access method using carrier sense, and avoids interference by using RTS / CTS control signals. If the sending node sends an RTS (Request To Send) message and the receiving node is able to receive it, CTS
(Clear To Send: ready to receive) Send a message. Surrounding nodes are RTS / CT
Since the S message is monitored, collision is prevented by refraining from data transmission while other nodes are transmitting data. Here, in the existing system, a frequency (control channel) for performing RTS / CTS control is different from a frequency (data channel) for actually performing communication. In the present embodiment, it is assumed that the RTS message and the CTS message include location information of a node that transmits the message. The position information is typically latitude / longitude information acquired from a GPS device. Although not essential, the position information is included not only in the message transmitted through the control channel but also in the message transmitted through the data channel.

  The cognitive system performs communication using at least the same frequency as the data channel of the existing system. Therefore, it is necessary to control the transmission output so that the existing system is not interfered by communication on the data channel. Here, the wireless communication device in the cognitive system estimates the amount of interference that the transmission of the data channel gives to the existing system based on the control channel transmitted from the existing system, so that the amount of interference is below the allowable level. Controls transmission output.

<Device configuration>
FIG. 1 is a schematic diagram showing a functional configuration of a radio communication device (cognitive radio communication device) constituting the cognitive radio communication system according to the present embodiment. The wireless communication device 1 includes an antenna 2, a high frequency unit 3, an AD conversion unit 4, a digital signal processing unit 5, a GPS device 6, and a map database 7. The high-frequency unit 3 receives a radio signal and converts it to a frequency band that facilitates digital signal processing, or converts a transmission signal to a frequency that is actually transmitted. The AD conversion unit 4 converts the received analog signal into a digital signal, and converts the digital signal to be transmitted into an analog signal. Note that the wireless communication apparatus 1 collectively AD-converts a wideband signal (for example, 900 MHz to 5 GHz) received from the antenna 2 and realizes demodulation processing including channel selection in the digital signal processing unit 5. To do.

The digital signal processing unit 5 can be configured by a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), a dynamic reconfigurable processor, or the like. The digital signal processing unit 5 includes a communication control unit 51 and a received power measurement unit 52 as functional units. The digital signal processing unit 5 requires other functional units for modulation / demodulation and the like, but these are well-known and will not be described in detail.

  The communication control unit 51 performs a connection establishment process, a data transmission / reception process, a process for notifying a communication partner of a channel usage status, a process for selecting a channel to be used, and the like. The received power measuring unit 52 receives the control channel of the primary user and measures the received power.

  The GPS device 6 receives a GPS signal from a GPS satellite or the like and acquires position information (latitude / longitude information). The map database 7 includes information such as road width, road connection angle at intersections, and the position and height of buildings.

<Processing flow>
FIG. 2 is a flowchart showing a process flow in which the cognitive radio communication apparatus according to the present embodiment determines the transmission output. First, the control channel of the primary user is received, and the received power measuring unit 52 measures the received power (S100). Next, the communication control unit 51 estimates the amount of interference given to the primary user when the data channel is transmitted with a predetermined transmission output (S102). A specific method for estimating the amount of interference will be described later. The predetermined transmission output is typically the maximum transmission output that can be transmitted by the wireless communication device 1, but may be any output within the maximum transmission output.

  Next, it is determined whether the estimated amount of interference is equal to or greater than the allowable level of the primary user (S104). It is assumed that the radio communication apparatus 1 knows in advance the interference level that can be accepted by the primary user. If the amount of interference is within an allowable level (S104-NO), the data channel is transmitted with a predetermined transmission output. On the other hand, when the amount of interference exceeds the allowable level (S104-YES), the transmission output is changed so that the amount of interference falls within the allowable level (S106).

  Note that connection establishment between secondary users can be performed by various methods. Also in the cognitive system, the control channel and the data channel may have different frequencies, or only one frequency channel may be used. When the control channel and the data channel are different, the control channel can be transmitted with an arbitrary transmission output as long as the control channel frequency and the primary user frequency are different, but the same control channel as the primary user is used. If this is the case, it is also necessary to transmit at an output that does not interfere with the primary user. And in the transmission of the data channel which is the same frequency as a primary user, it transmits with the transmission output calculated | required above.

  FIG. 3 is a diagram for explaining underlay cognitive radio communication according to the present embodiment. In the figure, node N is the wireless communication device 1 (secondary user), and nodes A and B are wireless communication devices (primary users) of the existing system. A circle 11 indicated by a dotted line indicates the wireless communication range of the control channel of the primary user A, and a circle 12 indicated by a dotted line indicates the wireless communication range of the control channel of the primary user B. The secondary user N determines the transmission output from the control channel received from the primary user A so that the primary user A is not included in the range 21 in which the amount of interference given to the primary user on the data channel is greater than or equal to the allowable level. Similarly, the secondary user N determines the transmission output from the control channel received from the primary user B so that the primary user is not included in the range 22 in which the amount of interference given to the primary user on the data channel is greater than or equal to the allowable level. In the case of FIG. 3, since the control channels are received from the two primary users, two transmission outputs are also determined. However, since any primary user should not be given interference above the allowable level, The smaller transmission output is selected. That is, in the example shown in FIG. 3, the transmission output is selected so that the interference range of the data channel is the range indicated by the circle 21.

<Method of estimating the amount of interference>
Next, a method for estimating the amount of interference with the primary user will be described. Although several methods can be considered as this estimation method, the present embodiment is characterized in that the position information included in the control channel of the primary user and the position information obtained from the GPS device 6 of the own terminal are used. Hereinafter, each estimation method will be described.

  The first estimation method is a method that uses a propagation loss calculated using a radio wave propagation model using the distance between transmission and reception and the frequency as parameters. FIG. 4A shows a flowchart of the first estimation method.

First, a distance (inter-transmission / reception distance) between the primary user and the secondary user is calculated from the position information included in the control channel of the primary user and the position information obtained from the GPS device 6 by the secondary user (S210).

と表される。ここで、Ａ、Ｂ、Ｃは定数であり、ｄは送受信間距離［ｍ］、ｆは送信周波数［Ｈｚ］である。なお、伝搬モデルでは送受信装置のアンテナ高を考慮することが多いが、車車間通信においてはアンテナ高がほぼ一定となることから定数Ｃにアンテナ高が含まれると考えても良い。このような電波伝搬モデルとして、奥村−奏モデル、Walfisch−池上モデル、坂上モデルなどを例に挙げることができる。 Next, the amount of interference is estimated based on the radio wave propagation model (S212). The radio wave propagation model used here is, for example,

It is expressed. Here, A, B, and C are constants, d is a distance between transmission and reception [m], and f is a transmission frequency [Hz]. In the propagation model, the antenna height of the transmission / reception apparatus is often taken into account, but in vehicle-to-vehicle communication, the antenna height may be considered to be included in the constant C because the antenna height is substantially constant. Examples of such radio wave propagation models include the Okumura-Kana model, the Walfisch-Ikegami model, the Sakagami model, and the like.

と推定することができる。 Here, the distance obtained in step S200 is applied to the distance d between transmission and reception. The transmission frequency f is the frequency of the data channel. And if the predetermined transmission output of the wireless communication device 1 (secondary user) is Pt2, the interference amount Z given to the primary user is

Can be estimated.

  The second estimation method is the same as the first method in that a radio wave propagation model is used, but differs in that a model that considers road width, road angle, building height, and the like is used. As such a radio wave propagation model, an extended Sakagami model, Taga model, etc. can be cited as examples. FIG. 4B shows a flowchart of the second estimation method.

  In this method, information such as surrounding roads and buildings is required, and therefore such information is acquired from the map database 7 based on the position information. Others are the same as those in the first method, and thus detailed description thereof is omitted.

  Although the radio wave propagation model (propagation loss estimation formula) is used in the first and second methods, the amount of interference given to the primary user in the data channel may be estimated by performing a radio wave propagation simulation. Since the position information of the primary user and the secondary user can be acquired respectively, radio wave propagation simulation can be performed if other information (for example, map data) necessary for the simulation is stored in the wireless communication device 1.

  The third estimation method is a method of estimating the propagation loss in the control channel and estimating the propagation loss in the data channel based on this. FIG. 4C shows a flowchart of the third estimation method.

First, the point of obtaining the distance between the primary user based on the position information included in the control channel and the position information obtained from the GPS device 6 is the same as in the first and second methods (S230). Next, the propagation loss at the control channel frequency is estimated from the received power of the primary user control channel and the propagation model (S232). Then, the amount of interference in the data channel is estimated using the propagation loss in the data channel that can be calculated from the propagation loss in the control channel (S234).

の関係がある。したがって、制御チャネルでの伝搬損失Ｐ／Ｐｔ１が求まる。一方、伝搬損失は周波数の２乗に比例するので、セカンダリーユーザがデータチャネルを送信出力Ｐｔ２で送信した場合に、プライマリーユーザに与える干渉量Ｚは、

と表せる。このようにして、データチャネルにおいてプライマリーユーザに与える干渉量を推定することもできる。 Between the transmission power Pt1 of the primary user and the reception power P of the control channel of the secondary user, l _f (fc, d) is a free loss when the control frequency is fc and the distance is d, l
_ray Rayleigh loss, a _{n c} as noise power,

There is a relationship. Therefore, the propagation loss P / Pt1 in the control channel is obtained. On the other hand, since the propagation loss is proportional to the square of the frequency, when the secondary user transmits the data channel at the transmission output Pt2, the interference amount Z given to the primary user is

It can be expressed. In this way, the amount of interference given to the primary user in the data channel can also be estimated.

  The fourth estimation method is a method applicable when the transmission output of the control channel of the primary user is known. The transmission output of this control channel may be known in advance by the secondary user (wireless communication apparatus 1), or may be included as information in the control channel. In this case, since the propagation loss between the primary and secondary of the control channel is known, even if there is one unknown parameter in the radio wave propagation model, this unknown parameter can be calculated.

  FIG. 4D shows a flowchart of the fourth estimation method. The point of calculating the distance to the primary user based on the position information (S240) is the same as in the first to third methods. Next, the parameter of the radio wave propagation model is estimated from the transmission output of the control channel of the primary user and the received power of the secondary user (S242). For example, in the above equation (1), the constant A may be regarded as an unknown parameter, and the constant A may be determined from the propagation loss of the control channel. Further, when the radio wave propagation model using the road width as a parameter is used and the wireless communication apparatus 1 does not include a map database, the road width can be estimated as a model parameter.

  When receiving control channels from a plurality of primary users, model parameters can be estimated based on the received power. The model parameters to be estimated should originally be the same value, but do not have the same value due to the influence of error or the like. Therefore, when a plurality of model parameters are estimated, it is also preferable to use an average value. Here, a simple average (arithmetic average) may be used, or a weighted average (for example, a weighted average using a weighting coefficient of the reciprocal of the distance) may be used as the distance from the primary user is closer. This is because it is considered that the model parameter based on the received power of the control channel from the primary user is obtained more accurately as the distance from the primary user is closer.

  After the model parameters are estimated, the amount of interference in the data channel is estimated by applying the radio wave propagation model as in the first and second estimation methods (S244).

<Operation / Effect of this embodiment>
According to the present embodiment, when communication is performed using the same frequency as the primary user (existing system), interference given to the primary user can be suppressed. At this time, since it is not necessary to transmit channel information from the existing system, it is not necessary to make a special change to the existing system. And the use efficiency of a frequency improves by using the same frequency as a primary user.

(Second Embodiment)
In this embodiment, since it is not accurate if the amount of interference estimation is performed with only one cognitive radio communication device, the accuracy is improved by cooperation of a plurality of cognitive radio communication devices. This is effective when using the method (FIG. 4D, the fourth estimation method) for estimating the model parameter of the radio wave propagation model based on the received power of the control channel described in the first embodiment. In other words, the model parameters estimated by each cognitive radio communication device are notified between the devices, so that more accurate model parameters are obtained, and the amount of interference is estimated based on this, thereby improving the accuracy of the estimation. .

  FIG. 5 is a flowchart showing a flow of processing in which the cognitive radio communication apparatus according to the present embodiment determines the transmission output. FIG. 6 is a diagram for explaining processing in which the cognitive radio communication apparatus according to the present embodiment determines the transmission output.

  The cognitive radio communication device (secondary user) receives the control channel transmitted by the primary user and measures the received power (S300). Here, it is assumed that the secondary user knows in advance the transmission power of the primary user's control channel or that the primary user's control channel includes the transmission power. That is, it is assumed that the secondary user knows the transmission power of the control channel of the primary user.

  Next, the secondary user estimates the model parameter of the radio wave propagation model in the same manner as the fourth estimation method of the first embodiment described above (S304). For example, the constant A in the above equation (1) is estimated. Here, if the distance and position information between the secondary user and the primary user are necessary, the position information included in the control channel may be used. Even when the secondary user can receive control channels from a plurality of primary users, it may be handled in the same manner as the method described in the fourth estimation method of the first embodiment. In this case, the distance to the primary user transmitted to the surroundings may be the average of the distances with a plurality of primary users, or may be the distance of the nearest primary user.

として決定する。なお、ここでは距離の逆数を重み付け係数とする加重平均を用いたが、距離が近いほど重みが大きくなるような加重平均であれば他の手法を採用してもかまわない。このようにして、全てのセカンダリーユーザにおいて、同一のモデルパラメータＩを導くことができる。 The secondary user notifies the surrounding secondary users of the estimated model parameters and the distance to the primary user (S304). This notification may be performed by any method as long as it does not interfere with the primary user. For example, transmission may be performed at the same frequency as the control channel of the primary user and with a transmission output that does not interfere with the primary user. In this case, the amount of interference from the secondary to the primary is estimated based on the received power of the control channel. Further, for example, transmission may be performed using a frequency different from the frequency used by the primary user. For example, in FIG. 6, the model parameter estimated by the secondary user Nn (n = 1 to 3) is In, and the distance between the secondary user Nn and the nearest primary user is rn. The secondary user N1 estimates the model parameter I1 and the distance r1 by itself, and acquires the model parameters I2 and I3 and the distances r2 and r3 from the secondary users N2 and N3, respectively. The same applies to other secondary users. And the secondary user uses the model parameter used for the amount of interference estimation,

Determine as. Here, the weighted average using the reciprocal of the distance as a weighting coefficient is used. However, other methods may be adopted as long as the weight is larger as the distance is closer. In this way, the same model parameter I can be derived for all secondary users.

  The secondary user applies the model parameter I obtained by weighting according to the distance to the radio wave propagation model, and estimates the amount of interference to the primary user when the data channel is transmitted with a predetermined transmission output (S308). . It is determined whether the amount of interference is equal to or greater than the allowable level of the primary user (S310). Assume that the secondary user knows in advance the interference level that the primary user can tolerate. If the amount of interference is within an allowable level (S310-NO), the data channel is transmitted with a predetermined transmission output. On the other hand, when the amount of interference exceeds the allowable level (S310-YES), the transmission output is changed so that the amount of interference is within the allowable level.

  According to this embodiment, since a plurality of secondary users cooperate to estimate model parameters, more accurate model parameters can be estimated, and as a result, the accuracy of estimating the amount of interference to the primary user is improved. Therefore, interference with the primary user can be prevented more effectively.

(Third embodiment)
In this embodiment, an array antenna whose directivity is adjustable is adopted as the antenna 2 and the directivity is adjusted so as to exclude transmission of radio waves to the position of the primary user.

  FIG. 7 is a flowchart showing a process flow in which the cognitive radio communication apparatus according to the present embodiment determines a transmission method. FIG. 8 is a diagram for explaining processing in which the cognitive radio communication apparatus according to the present embodiment determines a transmission method.

  The cognitive radio communication device (secondary user) receives the control channel transmitted by the primary user and measures the received power (S400). Next, even if the primary user's direction is excluded from the radio wave transmission range based on the position information of the primary user included in the control channel, the position information of the own node, and the position information transmitted from another secondary node. It is determined whether the positional relationship is such that communication with other secondary users is possible (S402). If the primary user direction is excluded and communication with other secondary users cannot be performed (S402-NO), the process proceeds to step S404, and the transmission output is determined in the same manner as in the first embodiment. In addition, when a primary user direction is excluded, the case where it cannot communicate with another secondary user is a case where another secondary user and a primary user are located in the same direction.

  On the other hand, if communication with another secondary user is possible even if the direction of the primary user is excluded from the radio wave transmission range (S402-YES), the process proceeds to step S410, the predetermined transmission output is used (S410), and the primary user The directivity of the antenna is controlled so as to exclude the position (S412). The case where communication with other secondary users is possible even if the direction of the primary user is excluded is typically the case as shown in FIG. 8, and the secondary users N1 to N3 are in the directions of the primary users A and B, respectively. You can communicate with each other even if you exclude.

  In this way, by adjusting the directivity, the secondary user can transmit the data channel with a larger transmission output without causing interference to the primary user, so that the frequency can be used more efficiently.

(Modification)
The first to third embodiments can be implemented in combination as appropriate. For example, in the third embodiment, when it is not possible to cope with directivity control, the transmission output may be determined by the same method as in the second embodiment.

  In addition, the directivity control in the third embodiment is applied only when the estimation in the second embodiment and the distance between the model parameter and the primary user are notified to the surrounding secondary nodes (step S304 in FIG. 5). Anyway. In this way, model parameters and the like can be exchanged with a larger number of secondary users, and the amount of interference can be estimated more accurately.

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 2 Antenna 3 High frequency part 4 AD conversion part 5 Digital signal processing part 6 GPS apparatus 7 Map database

Claims (5)

Radio that transmits data using the second frequency in the presence of another wireless communication device that transmits data on the second frequency channel after transmitting a control message including position information on the first frequency channel A communication device,
Position information acquisition means for acquiring position information;
Control channel receiving means for measuring received power of a control message transmitted by the other wireless communication device on the first frequency channel;
Based on the position information acquired from the position information acquisition means and the position information included in the control message, the amount of interference exerted on the other wireless communication device when data is transmitted at the second frequency is estimated. Interference amount estimation means;
Transmission output control means for controlling the transmission output at the second frequency in accordance with the estimated amount of interference;
With
The other wireless communication device stores in advance the transmission power of the control message transmitted by the first frequency channel, or acquires the transmission power,
The interference amount estimation means is based on position information acquired from the position information acquisition means and position information included in the control message in a radio wave propagation model using a distance between transmission and reception, a transmission frequency, and an unknown parameter as parameters. The unknown parameter in the radio wave propagation model is determined from the distance to the other wireless communication device obtained in the above, the first frequency, the transmission power and the reception power of the control message, and the radio wave propagation model is used. Estimating the amount of interference exerted on the other radio communication device when transmitting data at the second frequency
Wireless communication device. Transmitting the unknown parameter of the radio wave propagation model obtained by the interference amount estimating means and the distance to the other wireless communication device to a second wireless communication device;
Receiving an unknown parameter and a distance from the other wireless communication device from a second wireless communication device;
Each of the unknown parameter received from the second wireless communication device and the unknown parameter determined by itself is calculated as a weighted average multiplied by a larger weighting factor as the distance to the other wireless communication device is closer,
Applying a weighted average unknown parameter to the radio wave propagation model to estimate the amount of interference exerted on the other wireless communication device when transmitting data at a second frequency;
The wireless communication apparatus according to claim 1 . Radio that transmits data using the second frequency in the presence of another wireless communication device that transmits data on the second frequency channel after transmitting a control message including position information on the first frequency channel A communication device,
Position information acquisition means for acquiring position information;
Control channel receiving means for measuring received power of a control message transmitted by the other wireless communication device on the first frequency channel;
Based on the position information acquired from the position information acquisition means and the position information included in the control message, the amount of interference exerted on the other wireless communication device when data is transmitted at the second frequency is estimated. Interference amount estimation means;
Transmission output control means for controlling the transmission output at the second frequency in accordance with the estimated amount of interference;
Equipped with a,
The interference amount estimating means is the other radio communication apparatus obtained based on the received power of the first frequency channel, the position information acquired from the position information acquiring means and the position information included in the control message. The propagation loss at the first frequency is estimated from the distance to the first frequency, the propagation loss at the second frequency is estimated from the result, and the data is transmitted to the other radio communication device at the second frequency. Estimating the amount of interference,
Wireless communication device. For each of a plurality of other wireless communication devices, the amount of interference is estimated by the amount of interference estimation means,
The transmission output control means determines the transmission output at the second frequency so as to be equal to or less than a predetermined amount of interference for any of the plurality of other wireless communication devices.
The wireless communication apparatus according to any one of claims 1 to 3 . It has an antenna that can control the directivity,
Based on the position information included in the control message received from the other wireless communication device and the position information obtained from the position information acquisition unit, the radio waves are not transmitted in the direction in which the other wireless communication device is located. Control antenna directivity,
The radio | wireless communication apparatus in any one of Claims 1-4 .

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