JP2009010551A - Method of estimating propagation environment and transmission control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform transmission control by estimating a propagation environment between other stations and using the results of the estimation under such an environment where the other stations having no simultaneous transmission function coexist. <P>SOLUTION: Transmission signals of the other stations 13 and 14 are intercepted, propagation environments between a self-station and the other stations which are represented by propagation loss between the self-station 11 and the other stations are estimated from a difference between their transmitted power and received power, and a propagation environment between the other stations is estimated on the basis of the two results of estimating the propagation environments between the self-station and the other stations. Simultaneous transmission is executed between a link between the other stations, and a link between the self-station and the other stations on the basis of the result of estimating the propagation environment between the other stations. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system in which a plurality of radio stations transmit signals at the same time, and more particularly to a propagation environment between neighboring radio stations in order to make a decision for simultaneous transmission in which radio stations transmit simultaneously with signals from other stations. And a transmission control method using the estimation result.

  Conventionally, in a wireless communication system that performs packet wireless transmission such as a wireless LAN, an access control method based on carrier sense has been widely used. For example, Non-Patent Document 1 describes a CSMA / CA method using RTS and CTS in addition to carrier sense based on received signal strength. The purpose of CSMA / CA is to avoid collision of packets caused by so-called hidden terminals that cannot detect the presence of the local station but interfere with a communication partner station. However, in the above CSMA system and CSMA / CA system, once the interference signal is detected by the carrier sense function, even if the received signal strength is weak enough not to hinder the intended communication, the local station transmits. Since the so-called “exposed terminal problem” occurs, the transmission capacity of the entire system is limited.

  FIG. 33A is a system conceptual diagram for explaining the operation of the conventional CSMA method, and FIG. 33B is a diagram showing a temporal sequence of packet transmission in the system. In FIG. 9, 101-104 are radio stations. The wireless station 101 transmits data to the wireless station 102 and the wireless station 103 transmits data to the wireless station 104 based on the CSMA method. In FIG. 33B, first, the wireless station 103 performs carrier sense (CS), and transmits data to the wireless station 104 because no carrier is detected. When the wireless station 101 attempts to start transmission during transmission of this data, carrier sense (CS) is first performed. Then, since the data signal transmitted by the wireless station 103 is detected, transmission is prohibited. Conversely, when the wireless station 103 tries to start transmission when the wireless station 101 is transmitting, the wireless station 103 detects the signal of the wireless station 101 by carrier sense, and thus transmission is prohibited.

  Even if the intensity of the interference wave applied from the wireless station 101 to the wireless station 104 is sufficiently weak compared to the intensity of the desired wave addressed to the wireless station 104 from the wireless station 103 and does not hinder communication, such a transmission prohibited state as in FIG. Therefore, the transmission capacity of the entire system cannot be improved.

  Propagation between other stations (for example, between the radio station 103 and the radio station 104) where the peripheral station (for example, the radio station 101) desiring to transmit with delay has started communication as a factor that causes such an exposed terminal problem. When the environment (for example, the intensity of a desired wave in the wireless station 104) cannot be known and the local station (the wireless station 101) performs simultaneous transmission with another station (the wireless station 103), the other station (for example, wireless Since it cannot be determined whether or not it becomes an obstacle to reception of the station 104), transmission control is performed based on rough information such as a threshold of signal strength from other stations by carrier sense.

  To deal with this problem, Non-Patent Document 1 discloses a technique for estimating a propagation environment between other peripheral stations by adding and transmitting a propagation environment information to a packet defined by a conventional wireless LAN standard. . FIG. 34 is a conceptual diagram of a wireless system using the technology of Non-Patent Document 1. In the wireless system of Non-Patent Document 1, RTS packets (hereinafter abbreviated as RTS) and CTS packets (hereinafter abbreviated as CTS), which are mechanisms defined in the IEEE 802.11 standard, are used. It is assumed that.

  First, RTS / CTS will be described with reference to FIG. The transmitting station 103 transmits an RTS to the receiving station 104 before data transmission. The receiving station 104 that has received the RTS returns a CTS to the transmitting station 103. The transmitting station 103 recognizes that the receiving station 104 can receive the data by receiving the CTS, and starts data transmission. The RTS / CTS describes information on the period during which the carrier is used. A radio station that has received the RTS / CTS other than the transmitting station 103 and the receiving station 104 can stop transmitting the usage period described in the RTS / CTS. Thus, it is possible to avoid collision of signals between the transmitting station 103 and a hidden terminal (for example, the wireless station 105) that is visible from the receiving station 104 but not from the transmitting station 103. Thus, RTS / CTS is defined in the IEEE 802.11 standard for the purpose of dealing with the so-called hidden terminal problem.

  In Non-Patent Document 1, in order to cope with the exposed terminal problem, it is proposed that the receiving station 104 measures the received power of the RTS, adds a propagation environment parameter such as the received power information to the CTS, and sends it back. . When the peripheral terminal that has received the CTS estimates the propagation environment between the other stations from the propagation environment parameters added to the CTS, it can be determined from the estimation result that there is no hindrance to communication between the other stations even if the local station transmits it. , It does not necessarily stop transmission, and performs simultaneous transmission. In this way, the transmission capacity of the entire system is improved.

  The case where the transmitting station 103 transmits data to the receiving station 104 will be described more specifically. The transmitting station 103 transmits an RTS to the receiving station 104 before transmitting data, and the receiving station 104 transmits a CTS to the transmitting station 103. Here, the receiving station 104 adds the RTS received power information (desired wave power information), which is the desired wave, and the interference wave power information of the interference wave received by the receiving station 102 to the CTS and returns the CTS. When the neighboring radio station 101 receives the CTS, it extracts the desired wave power information and the interference wave power information added as described above, and measures the received power of the CTS. If the wireless station 101 and the transmitting station 103 perform transmission with equal power, the wireless station 101 transmits the interference wave power of the receiving station 104 by the amount of CTS received power measured by the local station when the local station transmits. Is estimated to increase. Based on the above-described power information extracted from the CTS and the estimation result of the interference wave power, the wireless station 101 calculates the ratio (SIR) of the desired wave power and the interference wave power at the receiving station 104 when the local station transmits. . If the wireless station 101 determines that there is no hindrance to reception of the receiving station 104 even if the local station transmits simultaneously, the wireless station 101 transmits an RTS to the wireless station 102 that is the communication partner of the local station, and the transmitting station 103 Simultaneous transmission with.

As described above, in Non-Patent Document 1, by adding the received power information and the interference power information to the CTS, the surrounding radio stations can communicate with each other between the inter-station propagation environment between 103 and 104, and between the 102 and the own station 101. The propagation environment (own station-other station propagation environment) is estimated.
Interference Aware (IA) MAC: an Enhancement to IEEE 802.11b DCF / IEEE VTC Fall 2003

  However, the wireless system of Non-Patent Document 1 is premised on using RTS / CTS. Although RTS / CTS is an effective technique when the density of radio stations is high, there is a problem that overhead is increased because a communication band is used for exchanging RTS / CTS as control packets. In addition, since the technology of Non-Patent Document 1 adds a new mechanism to RTS / CTS defined in the conventional IEEE 802.11 standard, it is effective only between wireless stations equipped with the technology of Non-Patent Document 1. I can't show it. For this reason, a radio station equipped with the technology described in Non-Patent Document 1 is installed in an environment where an existing radio station conforming to standards such as IEEE 802.11a / b / g that is widely used in the world operates. However, there is a problem that the improvement effect on the exposed terminal problem cannot be obtained so much.

  For example, as shown in FIG. 35, at home A, even if the wireless LAN system is constructed by mounting the technology of Non-Patent Document 1 on all the radio stations A1 and A2, the adjacent home B has IEEE802.11a / In an environment where radio stations B1 and B2 conforming to the b / g standard are used, the CTS transmitted by the radio station of the house B does not include the received power information and the interference power information described above. When the station intercepts the transmission signal of the wireless station of house B at an intensity exceeding the carrier sense threshold, the intensity of the interference wave received by the wireless station of house B when the wireless station of house A transmits Even if the intensity is weak enough not to hinder communication in the house B, the radio station in the house A does not transmit. Thus, in the environment as shown in FIG. 35, the terminal problem is also caused.

  The present invention has been made in view of such a situation, and the existing wireless station and the wireless station equipped with the technology of the present invention coexist without using RTS / CTS. Of a propagation environment estimation method and an estimation device between other stations that enable a propagation environment between other stations including a wireless station, and a transmission control method that exhibits an improvement effect on a terminal problem exposed by using the estimation method For the purpose of provision.

  In order to solve the above problems, the present invention provides a propagation environment estimation method in which a wireless station (own station) estimates propagation environment parameters between other wireless stations (other stations). A first step of receiving a first other station signal and estimating a first propagation environment parameter between the first other station and the own station; and a second step transmitted by the second other station. A second step of receiving a second station signal and estimating a second propagation environment parameter between the second station and the second station; and the first and second steps estimated by the second step. The inter-station propagation environment estimation step in which the own station estimates the inter-station propagation environment parameter between the first other station and the second other station based on the inter-station propagation environment parameter estimation result. Yes.

  The propagation environment parameter is, for example, a propagation loss between radio stations, and in the first step, from the transmission power of the first other station signal and the reception power when the own station receives the second other station signal. , Estimating the first inter-other-station propagation loss, and in the second step, from the transmission power estimation value of the second other-station signal and the received power when the own-station received the second other-station signal The second propagation loss between the own station and the other station is estimated. Then, in the inter-station propagation environment estimation step, the inter-station propagation loss between the first and second other stations is estimated based on the estimation results of the first and second own-other station propagation losses.

  Based on the estimation result, for example, based on the larger one of the first and second own-other-station propagation loss estimated values, a predetermined error margin (0 or a negative value is also included) The value including the above may be estimated as the propagation loss between other stations between the first and second other stations. Preferably, the predetermined error margin may be determined according to the difference value based on the difference between the first own-other station propagation loss and the second own-other station propagation loss. Also, when the estimation result is used as a basis, for example, when the difference between the first own-other station propagation loss and the second own-other station propagation loss is less than a predetermined value, May be estimated as the inter-other-station propagation loss between the first and second other stations.

  Further, in the inter-station propagation environment estimation step, based on the comparison result of the first and second own-other-station propagation loss, as the other-station propagation loss between the first and second other stations, If at least one of the first and second other station signals includes information that indicates the minimum reception power (minimum reception sensitivity) necessary for establishing communication between the other stations, Based on the difference between the minimum reception sensitivity obtained from the information and the transmission power, the first and second inter-station propagation losses are estimated, and both are compared, and the smaller value is set to the first and second values. It is desirable to estimate the propagation loss between other stations between other stations.

  Further, the propagation environment parameter may be, for example, transmission power and reception power of a radio station. In this case, in the first and second steps, the transmission power of the first and second other station signals and the reception power when the own station receives the first and second other station signals are estimated. Then, in the inter-station propagation environment estimation step, the transmission power difference value, which is the difference between the transmission power of the first other station signal and the transmission power of the second other station signal, the first reception power, and the second reception The received power difference value that is the difference from the power is compared, or the first difference value that is the difference between the transmission power of the first other station signal and the first received power and the transmission of the second other station signal. The second difference value that is the difference between the power and the second received power is compared, and based on the comparison result, the received power of the first other station signal in the second other station and the first other station Both or one of the received powers of the second other station signal may be estimated. Further, when at least one of the first and second other station signals includes information that indicates the minimum received power (minimum reception sensitivity) necessary for establishing communication between the other stations. Then, the minimum reception sensitivity obtained from the information is compared with the reception power of the other station signal at the first or second other station estimated by the above-described method, and the larger value is set to the first or second value. It is desirable to estimate the received power of the other station signal at the other station.

  When the transmission power information is included in at least one of the first and second other station signals, the own station obtains the transmission power of the other station signal from the transmission power information in the first and second steps. It may be estimated. When the transmission power information is not included in either the first or second other station signal, the transmission power of the other station signal is set to the industry average transmission power, the transmission power determined by the system, the past What is necessary is just to estimate by the average value etc. of the acquired transmission power information.

  Further, in order to improve the estimation accuracy of the propagation environment, in the inter-station propagation environment estimation step, the inter-station propagation between the first and second other stations estimated by the own station by at least one or more other stations. The method may further include a correction step of receiving the environmental parameter estimated value and correcting the inter-station propagation environment parameter estimated value between the first and second other stations based on the estimated value and the estimated value of the own station. desirable.

  In the correction step, for example, an average value of the estimated value of the own station and the estimated value of the other own station may be calculated, and the value may be used as the corrected inter-station propagation environment parameter estimated value. Alternatively, the maximum value or the minimum value of the estimated value of the own station and the estimated value of the other own station may be calculated, and the value may be used as the corrected inter-station propagation environment parameter estimated value.

  Further, in order to improve the estimation accuracy of the propagation environment, in the propagation environment estimation step between other stations, the own station is at least one other own station is the propagation environment parameter between other stations between the first and second other stations. The other-station propagation environment parameter between the first and second other stations estimated by the own station using the other-station estimation information received from the other-station estimation information. A correction step for correcting the estimated value may be further included. For example, the difference value between the first own-other-station propagation environment parameter and the second own-other-station propagation environment parameter estimated by the other own station may be used as the other-owner station estimation information. In this case, in the correction step, for example, the difference value between the first own-other-station propagation environment parameter estimated by the own station and the second own-other-station propagation environment parameter, and the difference value estimated by the other own station, When the average difference value is equal to or less than a predetermined value, the predetermined propagation environment parameter value may be used as the inter-other-station propagation environment parameter estimated value between the first and second other stations. Alternatively, the maximum or minimum difference between the difference value between the first own-other-station propagation environment parameter estimated by the own station and the second own-other-station propagation environment parameter and the difference value estimated by the other own station And when the maximum or minimum difference value is less than or equal to the predetermined value, the predetermined propagation environment parameter value is estimated as the inter-other-station propagation environment parameter estimation value between the first and second other stations. May be. Alternatively, when the number of difference values that are less than or equal to a predetermined value among a plurality of difference values estimated by the own station and other own stations is equal to or more than a predetermined value, the predetermined propagation environment parameter value is set to the first and second other values. It is good also as an inter-station propagation environment parameter estimated value between stations.

  Further, in order to improve the estimation accuracy of the propagation environment, the maximum propagation loss value between other stations is stored in advance in the own station, and in the propagation environment estimation step between other stations, between the estimated first and second other stations. When the estimated propagation loss between other stations is larger than the maximum stored propagation loss between other stations, the maximum propagation loss between other stations is corrected as the estimated propagation loss between other stations between the first and second other stations. A correction step may be further included. The maximum propagation loss between other stations may be determined, for example, by observing the surrounding environment by the user, or a mode selection switch is provided in the propagation environment estimation device, and the user selects the mode according to the usage environment. You may decide by.

  The propagation environment parameter is, for example, the propagation distance between the radio stations, and in the first step, from the transmission power of the first other station signal and the reception power when the own station receives the second other station signal. , Estimating the propagation distance between the first and second stations, and in the second step, from the estimated transmission power of the second other station signal and the received power when the own station receives the second other station signal , Estimating the second inter-station propagation distance, and in the inter-station propagation environment estimation step, the local station determines the first self-other station propagation distance estimate, Estimate the propagation distance between other stations by receiving the transmission signal from the other station and extract the transmission power of the transmission signal from the other station and the received power at the own station. The first-second propagation distance between the first and second stations estimated by the own station and the first and second estimated by the other own stations are estimated. The other stations among the propagation distance between the first other station and a second remote station is estimated by using the inter-own and other stations propagation distance and local station between the propagation distance.

  The propagation environment parameter is, for example, the position information of the other station and the propagation distance between the other stations. In the first step, the position information of the first other station is estimated by exchanging information between the plurality of own stations. In the second step, the location information of the second other station is estimated by exchanging information between the plurality of own stations, and the estimation is performed in the first and second steps in the inter-station propagation environment estimation step. The inter-station propagation distance between the first other station and the second other station is estimated from the position information of the first other station and the position information of the second other station. For example, the position information of the other station is received by the own station (own station) from two other own stations, the position information of the other own station, and the phase information when the other own station receives the other station signal. Calculate the difference in distance between the other station and each own station from the phase difference between the three own stations including the own station and the other station, and estimate the initial value setting between one of the own stations and the other station. The distance is assumed as the assumed distance, the distance between the other station and other stations is also assumed from the assumed distance, and the assumed position of the other station is determined using the assumed distance from each station and the position information notified from each station. Calculate and repeat the calculation while feeding back the calculated distance to the assumed distance until the difference between the calculated distance to the other station calculated from the calculated assumed position and the assumed distance to the other station is smaller than a specific value. Estimated using a position calculation method in which the assumed position when the difference between the distance and the assumed distance is less than a specific value is the position of the other station It may be Re.

  The propagation environment parameters are the propagation distance and propagation loss between radio stations, and the propagation loss between other stations is estimated based on the propagation distance between other stations estimated by the above-described method.

  In order to solve the above problems, the present invention provides a transmission link from a first other station to a second other station and a transmission from the first station to the second radio station. Other stations between the first other station and the second other station estimated using the above-described propagation environment estimation method as a method of estimating the transmission power of the own station that can simultaneously transmit without interfering with the link The received power at the second other station is estimated from the inter-station propagation loss estimated value and the transmission power of the signal transmitted from the first other station to the second other station, and the received power estimated value and the second other Based on the predetermined required CIR in the station and the second estimated propagation loss between other stations estimated using the above-described propagation environment estimation method, the transmission power of the own station that can be simultaneously transmitted is estimated.

  Alternatively, the transmission link from the first other station to the second other station and the transmission link from the first station to the second radio station may not interfere with each other at the same time. As a method for estimating the transmission power of the local station that can be transmitted, the first radio station transmits a signal transmitted from the first other station to the second other station estimated using the above-described propagation environment estimation method. Based on the received power at the second other station, the second estimated propagation loss between the other stations, and the predetermined required CIR at the second other station, the transmission power of the own station that can simultaneously transmit is estimated. To do.

  In addition, the local station simultaneously transmits packets from the local station at the timing at which the first other station overlaps the first transmission packet addressed to the second other station with the allowable transmission power that can be simultaneously transmitted estimated by the above method. Transmit and determine whether or not simultaneous transmission is possible based on the response result of the second other station or the presence / absence of a retransmission packet from the first other station with respect to the first transmission packet. When the first other station performs simultaneous transmission overlapping the time for transmitting a signal to the second other station and determines that simultaneous transmission is impossible, the first other station will continue to perform It is desirable not to carry out simultaneous transmission at the time of transmitting a signal to the second other station, or to reduce the allowable transmission power and retry the simultaneous transmission.

  As described above, according to the present invention, it is possible to estimate a propagation environment between other stations including an existing radio station without using RTS / CTS, and it is difficult to communicate between other stations based on the estimation result. In this environment, existing radio stations and radio stations equipped with the technology of the present invention coexist. In addition, the improvement effect on the exposed terminal problem can be exhibited.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a concept of a radio communication system according to Embodiment 1 of the present invention. In FIG. 1, 11, 12, 13, and 14 are radio stations. The wireless stations 11 and 12, 13 and 14 are communicating, respectively, d12 is a data packet addressed from the wireless station 11 to the wireless station 12, a21 is an ACK packet returned from the wireless station 12 to the wireless station 11 as a reception confirmation, d34 Is a data packet addressed from the wireless station 13 to the wireless station 14, and a43 is an ACK packet returned from the wireless station 14 to the wireless station 13 as a reception confirmation. The wireless stations 13 and 14 communicate in the adjacent house B, and the wireless stations 11 and 12 communicate in the home A. Hereinafter, the wireless stations 11 and 12 are referred to as own stations 11 and 12, respectively, and the wireless stations 13 and 14 are referred to as other stations 13 and 14, respectively.

  The own station 11 estimates the propagation environment between the other stations 13 and 14 using the propagation environment estimation method of the present invention to be described later, and at a timing overlapping with the communication timing between the other stations 13 and 14 based on the estimation result. It is determined whether or not communication between other stations will be hindered even if a packet is transmitted from the own station 11 (hereinafter referred to as simultaneous determination). If the own station 13 determines that there is no problem in communication between the other stations as a result of the simultaneous transmission determination, the data packet is transmitted regardless of the carrier sense result even when the packet is transmitted between the other stations 13 and 14. Are sent simultaneously.

  FIG. 2 is a diagram showing symbols representing the propagation environment between wireless stations and the propagation environment parameter of each station used in the description of the present invention. In FIG. 2, the symbols attached to the double-headed arrows represent the propagation loss and distance between the stations. That is, the propagation loss between the own station 11 and the own station 12 is L12, the distance between them is D12, the propagation loss between the own station 11 and the other station 13 is L13, the distance between them is D13, the own station 11 and the other station 14 is L14, the distance between them is D14, the propagation loss between the own station 12 and the other station 13 is L23, the distance between them is D23, and the propagation loss between the own station 12 and the other station 14 is L24. The distance between them is D24, the propagation loss between the other stations 13 and 14 is L34, and the distance between them is D34. In FIG. 2, the symbols attached to the starting point and ending point (point of the arrow) of the single arrow line are the transmission power when the packet of FIG. 1 is transmitted from the station located at the starting point of the line. It represents the received power when the packet is received at the station indicated by the arrow. That is, the transmission power of the packet transmitted from the own station 11 is P1, and the received power at each station when the packet is received by the own station 12 and the other stations 13 and 14 is R12, R13, R14, and the other station 13, respectively. The transmission power of the packet to be transmitted is P3, and the reception power at each station when the packet is received by the own station 11, 12 and other station 14 is the transmission of the packet transmitted from R31, R32, R34 and the other station 14, respectively. The power is P4, and the received power at each station when the packet is received by the own stations 11 and 12 and the other station 13 is R41, R42, and R43, respectively. Here, transmission power, reception power, and propagation loss are all values expressed in decibels.

  FIG. 3 is a diagram illustrating a transmission sequence until simultaneous transmission is attempted in the wireless communication system of FIG. Here, the other stations 13 and 14 perform carrier sensing (CS) for a predetermined time immediately before data transmission according to the conventional CSMA method, and when no carrier is detected, the other stations 13 and 14 transmit data packets. Also, the own station 11 performs carrier sense (CS) for a predetermined time until the allowable transmission power described later is determined, and transmits a data packet when no carrier is detected, as in the conventional CSMA method. . In FIG. 3, first, after the other station 13 performs carrier sense, the data packet d34 addressed to the other station 14 is transmitted, and the other station 14 transmits the ACK packet a43 immediately after receiving the data packet d34. The own station 11 detects the carrier of the data packet d34 when performing carrier sense until the allowable transmission power to be described later is determined, and is in a transmission prohibited state. Become. Here, similarly to the packet conforming to the 802.11a / b / g standard, the data packet d34 includes a source address and a destination address, and the ACK packet a43 includes a destination address (a source address of the data packet). ing.

  In the wireless communication system of the present embodiment, the own station 11 intercepts the other station signals d34 and a43 shown in FIG. 3, estimates the inter-station propagation environment between the other stations 13 and 14, and based on the estimation result. Even when a carrier is detected when the allowable transmission power is determined and carrier sense is performed, simultaneous transmission is attempted with the determined allowable transmission power. Whether or not the own station 11 can simultaneously establish a link to the radio station (for example, own station 12) of the communication partner of the own station 11 with respect to the link from the other station 13 to the other station 14. Judgment is made autonomously by the following procedure.

First, when the own station 11 intercepts the data packet d34 in FIG. 3, if the transmission power information of the other station 13 can be extracted from the data packet d34, the own station 11 estimates the transmission power P3 from the information and receives the received power R31. , And the propagation loss L13 between the own station 11 and the other station 13 is expressed as L13 = P3-R31 (1)
Estimate as In this way, when transmission power information can be extracted from other station signals, the propagation loss between the own station and other stations can be estimated with high accuracy by using the information. Next, when the own station 11 intercepts the ACK packet a43 in FIG. 3, if the transmission power information of the other station 14 can be extracted from the ACK packet a43, the transmission power P4 cannot be estimated and extracted from the information. The transmission power estimated when the data packet d34 is intercepted is estimated as the transmission power P4, the reception power R41 is measured, and the propagation loss L14 between the own station 11 and the other station 14 is expressed as L14 = P4-R41 ――― (Formula 2)
Estimate as When the transmission power information is not included in any of the other station signals d34 and a43 and the transmission power of both other stations cannot be accurately grasped, the local station 11 determines the industry average transmission power and its system. The predetermined transmission power such as the transmission power determined in step 1 and the average value of transmission power information acquired in the past may be determined and estimated as the transmission power P3. Thereby, even when transmission power information is not added to the other station signal, it is possible to estimate the propagation loss between the own station and the other station.

Next, the own station 11 compares the estimated two propagation losses L13 and L14 between the other stations and estimates the larger value as the other-station propagation loss L34 between the other stations 13 and 14. Then, the wireless station 11 determines the received power R34 of the data packet d34 at the other station 14 from the estimated transmission power P3 and the propagation loss L34 between other stations: R34 = P3-L34 (3)
Estimate as In addition, when the local station 11 can estimate the required CIR (referred to as CIR34) required when the other station 14 receives the data packet d34 from the information included in the intercepted data packet d34 or ACK packet a43, the information CIR 34 is estimated based on the above, and when the information for estimating CIR 34 is not included in data packet d 34 or ACK packet a 43, a predetermined required CIR value is estimated as CIR 34. Then, the own station 11 can transmit the data packet d34 from the estimated propagation loss L14, the received power R34, and the CIR 34 between the own station 11 and the other station at the same time without causing any trouble in communication between the other stations. Power P1 (hereinafter referred to as “allowable transmission power”) P1 = R34 + L14−CIR34 —— (Formula 4)
Determine as. If neither of the other station signals d34 and a43 includes information on the CIR 34, the local station 11 determines the predetermined required CIR, the industry average required CIR, the required CIR determined by the system, the past What is necessary is just to estimate by the average value etc. of the acquired required CIR. This makes it possible to estimate the inter-station propagation loss even when the required CIR information is not added to the other-station signal.

  As described above, the local station 11 determines the allowable transmission power for attempting simultaneous transmission by intercepting the data packet d34 and the corresponding ACK packet a43. Next, as shown in FIG. 3, the local station 11 again intercepts the data packet d34 for which the allowable transmission power has been determined, and when the packet 11 recognizes the packet as the data packet d34 from the header, Attempt simultaneous transmission of data packet d12 with transmission power P1. If the own station 12 can normally receive the data packet 12, it returns an ACK packet a21. Then, the local station 11 can intercept the ACK packet a43 and can also receive the ACK packet a21, or can receive the ACK packet a21 and the data packet d34 transmitted thereafter is not a retransmission packet. , Regarded as simultaneous transmission success. The own station 11 performs this simultaneous transmission trial a predetermined number of times, and when the number of successful simultaneous transmissions is equal to or greater than the predetermined number of times, the own station 11 communicates with the own station 12 from the other station 13 to the other station 14. Determine that the links can be established simultaneously. If the local station 11 holds data to be transmitted to the local station 12 regardless of the result of the carrier sense even during a period in which the data packet d34 is transmitted from the other station 13 to 14, the local station 11 receives the data packet d12. Are sent simultaneously. The local station 11 performs this simultaneous transmission trial a predetermined number of times, and if the number of successful simultaneous transmissions is less than the predetermined number, the local station 11 transmits a link from the local station 13 to the local station 14. It is determined that it is impossible to establish a link to the own station 12 at the same time, and transmission is prohibited according to the result of carrier sense as before.

  The local station 11 also extracts packet length information from the header of the data packet d34 when performing simultaneous transmission, and based on that information, the data packet d34 is almost simultaneously with the end of the data packet d34 as shown in FIG. The data length of d12 is controlled so that d12 ends. As described above, by arranging the transmission times of the links to be transmitted simultaneously, the time rate during which the simultaneous transmission is performed can be increased, and the transmission capacity can be improved more effectively. When the own station 12 has the same simultaneous transmission permission determination function as the own station 11, the data packet d12 to be transmitted simultaneously includes information indicating that simultaneous transmission is being performed. . The own station 12 does not transmit the ACK packet a12 corresponding to the data packet d12 performing simultaneous transmission immediately after the completion of d12, but transmits the ACK packet a12 with an interval for completing normal ACK transmission as shown in FIG. . This prevents a21 from colliding with the ACK packet a43. When the own station 12 is a station that does not have a mechanism for simultaneous transmission determination like the other stations 13 and 14, such as a wireless station conforming to the IEEE802.11a / b / g standard, the own station 11 first transmits the data packet d34. And when the ACK packet a43 is intercepted, from the reception end time of the data packet d34 to the reception start time of the ACK packet a43 is stored as a SIFS time, and when performing simultaneous transmission, from the header of the data packet d34 Based on the extracted packet length information and the stored SIFS time, the data length of d12 is controlled so that the data packet d12 ends when the SIFS time elapses from the end time of the data packet d34. Even if the communication partner's own station is a station that does not have a simultaneous transmission determination mechanism such as a wireless station conforming to the IEEE802.11a / b / g standard, the end time of the data packet d12 is set in this way in the data packet d34. By delaying from the end time and aligning around the start time of the ACK packet a43, the transmission start timing of the ACK packet a21 is delayed from the transmission start timing of the ACK packet a43, and the collision time between the ACK packet a43 and the ACK packet a21 is shortened. Therefore, the probability that the other station 13 and the own station 11 can normally receive the ACK packet for each data packet can be increased.

  In this embodiment, the data packet d12 to be transmitted at the time of simultaneous transmission trial is a data packet including the data when there is actually data to be transmitted from the local station 11 to the local station 12 at that time. If there is no data to be processed, a data packet including dummy data (for example, a random bit string) is used. In this way, by using data that actually needs to be transmitted and trying simultaneous transmission, a dedicated test packet for determining whether simultaneous transmission is possible is always used for simultaneous transmission attempts. Therefore, it is possible to determine whether or not simultaneous transmission with high frequency utilization efficiency is possible.

  FIG. 4 is a diagram illustrating a configuration example of the wireless communication device of the own station 11 in the wireless station of the present invention. In FIG. 4, 41 is a demodulator, 42 is a received power detector, 43 is a transmission power controller, 44 is a link information manager, 45 is a simultaneous transmission link manager, 47 is a transmitter, and s1 is an input signal from an antenna. , S2 is the demodulated data, s3 is the received power information of the received packet, s4 is the transmission power information permitted to the local station when performing simultaneous transmission, s5 is the transmission power control signal, s6 is the transmission data, and s7 is Simultaneous transmission link determination information, s9 is a simultaneous transmission timing signal, s10 is simultaneous transmission packet length information, and s12 is a transmission signal. The demodulator 41 receives and demodulates the input signal 41 from the antenna to obtain demodulated data. The demodulated data also includes header information of the packet being transmitted. The received power detector measures the received power of the received packet and outputs received power information s3.

  The link information management unit 44 extracts the header information of the packet transmitted from the demodulated data s2, and estimates the propagation loss of the link between other stations that cannot be extracted from the demodulated data using the measured received power s3. Remember. Further, the link information management unit 44 outputs the allowable transmission power information s4 permitted to the own station and the address information s7 of the received packet when simultaneously transmitting to the other station link currently being received based on the information. .

  The simultaneous transmission link management unit uses the address information s7 to determine the number of simultaneous transmission attempts to the transmission data of the other station currently being received, the number of successful simultaneous transmissions, and the local station address of the other party that has attempted the simultaneous transmission. Is stored, and it is determined whether or not there is a link of the own station capable of simultaneous transmission with respect to the transmission data of the other station currently being received. When it is determined that there is a link of the local station that can be simultaneously transmitted, a simultaneous transmission timing signal s8 for performing simultaneous transmission is output. Further, since the packet length information is extracted from the packet header of the demodulated data s2, and based on this, the end time of the packet to be simultaneously transmitted (simultaneous transmission packet) is almost the same as the packet end time of the link that is already being transmitted. Is determined as packet length information s9. Further, local station address information s10 indicating the local station address capable of simultaneous transmission is output. Note that the simultaneous transmission link management unit determines whether simultaneous transmission is possible even when there is a communication partner station of the local station where the number of simultaneous transmission attempts in the past with respect to transmission data of other stations currently being received is less than a predetermined number. In order to transmit a test packet for performing communication to the communication partner station, the address information of the communication partner station is output as its own station address information.

  When the transmission data S6 corresponding to the local station address information s10 exists, the transmission unit 46 receives it, generates a data packet, and generates and transmits a transmission signal s12. If there is no transmission data S6 corresponding to the local station address information s11, a data packet containing predetermined data is generated, and a transmission signal s12 is generated and transmitted. When following the CSMA procedure, the transmitter 46 performs carrier sense based on the received power s3 and determines whether or not transmission is possible. However, when the simultaneous transmission timing signal is received from the simultaneous transmission link management unit, a determination is made immediately to perform simultaneous transmission regardless of the carrier sense result by the received power s3, and the simultaneous transmission timing signal s8 and the packet length information s9 are determined. Then, a packet is generated based on the local station address information s10 and transmitted. When the transmission power information s4 is input, the transmission power control unit 43 determines the power of the transmission signal transmitted by the own station based on the information, and when there is no input of s4, selects the predetermined transmission power. The transmission power control information s5 is given to the transmitter for control.

  FIG. 5 is a diagram illustrating a configuration example of the link information management unit 44 in FIG. In FIG. 5, 51 is a required CIR information estimation unit, 52 is a transmission power information estimation unit, 53 is an address extraction unit, 54 is a propagation loss estimation unit between its own and other stations, 55 is a propagation loss storage unit between its own and other stations, and 56 is An inter-station propagation loss estimation unit, 57 is an inter-station propagation loss storage unit, and 58 is an allowable transmission power calculation unit. Description of other symbols that are the same as those in FIG. 4 is omitted.

  The required CIR information estimation unit 51 and the transmission power information estimation unit 52 respectively include the required CIR information at the destination station of the currently received signal and the transmission power information of the currently received signal in the demodulated data s2. Extracts the transmission power value and the CIR value from the demodulated data s2, and outputs them as transmission power information s12 and required CIR information s13. When the demodulated data s2 does not include required CIR information and transmission power information, predetermined transmission power values and CIR values are output as transmission power information s12 and required CIR information s13.

  The address extraction unit 53 extracts the transmission source address and the destination address of the packet included in the packet header information, and outputs them as address information s7. Note that in a wireless station or the like conforming to the IEEE802.11a / b / g standard, only the destination address (the source address that transmitted the data packet) is extracted from the ACK packet. However, the address extraction unit 53 intercepts the data packet, ACK packet is intercepted around the time when SIFS time elapses, and if the extracted destination address is the source address of the data packet just intercepted, this ACK packet Assuming that the data packet is transmitted from the destination station of the data packet intercepted in step S1, the source address is also output.

  The own-other station propagation loss estimation unit 54 estimates the own-other station propagation loss, which is a propagation loss between the own station and the other station, by subtracting the measured received power s3 from the transmission power value s12 of the other station. The own-other-station propagation loss estimated value s14 is output. The own-other-station propagation loss storage unit 55 recognizes the transmission source address included in the address information s7 and transmits the currently received signal and the other-station propagation loss estimated value for the other station. s14 is stored in the own-other station propagation loss storage table as shown in FIG.

  The other-station propagation loss estimation unit 56 recognizes the source address and destination address of the other-station signal included in the address information s7, and two own-other-station propagation loss estimation values corresponding to the two recognized addresses, respectively. Is referred to from the own-other-station propagation loss storage table of the own-other-station propagation loss storage unit 55. Then, the inter-other-station propagation loss estimation unit 56 compares the two own-other-station propagation loss estimated values, and determines the larger value between the other-station propagation losses corresponding to the source address and the destination address that are currently being received. The estimated value is s15. The inter-station propagation loss estimation unit 56 determines the inter-station propagation loss when the estimated propagation loss corresponding to the other-station address to be referred to is not yet stored in the own-other-station propagation loss storage table. The estimation is not performed, and the inter-station propagation loss estimated value s15 is not output.

  In the case where the own station 11 in FIG. 1 intercepts the signal of the link between the other stations 13 and 14 for the first time and estimates the propagation loss between the other stations 13 and 14, the propagation loss between the other stations is more specifically described. The process until estimation is described. First, the data packet d34 transmitted by the other station 13 is intercepted, and the own-other station propagation loss L13 between the own station 11 and the other station 13 is estimated by the own-other station propagation loss estimation unit 54. Although it is stored in the inter-station propagation loss storage unit 55, at this time, the own-other station propagation loss L14 between the own station 11 and the other station 14 is still stored in the own-other-station propagation loss storage unit 55. Therefore, the inter-station propagation loss estimation unit 56 does not perform inter-station propagation loss estimation. Next, when the other station 14 transmits an ACK packet a43 for the data packet d34 of the other station 13, the own station 11 intercepts the signal and the own-other station propagation loss L14 between the own station 11 and the other station 14 is detected. Is estimated by the own-other station propagation loss estimation unit 54 and stored in the own-other station propagation loss storage unit 55. At this point, since the own-other-station propagation loss estimation value for the other stations 13 and 14 exists, the other-station propagation loss estimation unit 56 compares the two other-station propagation loss estimation values, Is output as a propagation loss estimated value s15 between other stations 13 and 14. For example, when the propagation loss estimated value between the own station and the other station is shown in FIG. 7A, the estimated propagation loss value 71 (dB) between the own station 11 and the other station 14 is selected and the propagation loss L34 between other stations is selected. Is output as an estimated value.

  The inter-station propagation loss storage unit 57 recognizes the source address and the destination address included in the address information s7 and obtains the two addresses indicating the link of the signal currently being received and the inter-station propagation loss estimated value s15. This is stored in the inter-station propagation loss storage table as shown in FIG.

  The allowable transmission power estimation unit 58 recognizes the transmission source address and destination address of the other station signal included in the address information s7, and stores the propagation loss estimated value between other stations corresponding to the two recognized addresses. The destination station reception when the other station signal currently transmitted from the reference value and the transmission power information s12 is received by the other station designated by the destination address with reference to the other station propagation loss storage table of the unit 57 Estimate power. Next, the allowable transmission power estimation unit 58 refers to the own-other-station propagation loss estimated value corresponding to the destination address from the own-other-station propagation loss storage table of the own-other-station propagation loss storage 55, and receives the destination station. A value obtained by subtracting the required CIR estimated value s13 from the value obtained by adding the propagation loss estimated value between the own station and the other station to the estimated power value as the allowable transmission power estimated value s4 when simultaneously transmitting to the other station signal currently being received. Output.

  FIG. 6 is a diagram illustrating a configuration example of the simultaneous transmission link management unit 45 of FIG. In FIG. 6, 61 is a simultaneous transmission link storage unit, 62 is a packet length extracting unit, 63 is a simultaneous transmission determining unit 63 is a packet length calculating unit, s18 is stored simultaneous transmission link information, and s19 is extracted from demodulated data. Packet length information.

  The simultaneous transmission link storage unit 61 uses the address information s7 to determine the number of times that simultaneous transmission has been attempted for the currently received transmission data, the number of successful simultaneous transmissions, and the address of the other party that has attempted simultaneous transmission. It is stored in the simultaneous transmission link information table as shown in FIG.

  The simultaneous transmission determination unit 63 uses the address information s7 to recognize the link between other stations currently being received, and refers to the simultaneous transmission link information table so that the local station can simultaneously transmit the currently received transmission data. It is determined whether there is a communication partner. When simultaneous transmission trials have been performed a predetermined number of times for all the communication partner candidate stations of the local station, the simultaneous transmission determination unit 63 has the number of successful simultaneous transmissions in the simultaneous transmission link information table equal to or greater than the predetermined number The local station communication partner address is searched, and if the local station communication partner address can be found, the local station communication partner address is set as the local station address information s10, and the simultaneous transmission timing signal s8 for simultaneous transmission and the local station address information s10 are output. Note that the simultaneous transmission link determination unit 63, when there is a station whose number of simultaneous transmission attempts is less than the predetermined number among the communication partner candidate stations of its own station, In order to transmit to the communication partner station, the address information of the communication partner station is output as the own station address information 10.

  For example, it is assumed that the own station 9, 10, 12 exists as a communication partner of the own station 11. (It is assumed that the own stations 9 and 10 are operating in the home A although not shown in FIG. 1.) Then, in order to determine whether or not simultaneous transmission is possible, the predetermined number of times of simultaneous packet transmission is determined twice. Assume that the storage state of the simultaneous transmission link information table is the state shown in FIG. 7C when the local communication partner station having the number of successful simultaneous transmissions of 2 or more is a station capable of simultaneous transmission. In this case, since the number of simultaneous transmission attempts of the own station 12 which is the communication partner candidate station is less than the predetermined number for the other station signal addressed from the other station 13 to the other station 14, the simultaneous transmission link determination unit 63 When the transmission data currently being received from the address information s7 is recognized as a signal addressed from the other station 13 to the other station 14, the simultaneous transmission timing signal s8 and the own station address information s10 indicating the address of the wireless station 12 are obtained. Output. If the simultaneous transmission is successful as a result of trying the simultaneous transmission to the local station 12, the local station candidate station corresponding to the other station signal addressed from the other station 13 to the other station 14 in FIG. Since the number of simultaneous transmission attempts and the number of successful simultaneous transmissions of the station 12 are both two times, the simultaneous transmission link determination unit 63 next sends the transmission data currently being received from the address information s7 to the other station 14 from the other station 13. When the received signal is recognized, the simultaneous transmission timing signal s8 and the local station address information s10 including the addresses of the local stations 10 and 12 are output. On the other hand, since there is no local communication partner that can simultaneously transmit other station signals addressed to the other station 15 from the other station 13, the simultaneous transmission link determination unit 63 is currently receiving from the address information s7. If the transmission data is recognized as a signal addressed from the other station 13 to the other station 15, simultaneous transmission is not possible for the link, and neither the simultaneous transmission timing signal s8 nor the own station address information s10 is output.

  The packet length extraction unit 63 extracts packet length information from the demodulated data s2. The packet length calculation unit 65 obtains the length of the simultaneous transmission packet such that the packet length is shortened by the transmission start delay time at the time of simultaneous transmission with respect to the extracted packet length of the currently received packet. Output as long information s10. That is, the packet length is set so that the end time of the currently received packet and the simultaneous transmission packet to be transmitted is almost the same.

  By applying the above configuration to the own station 11 shown in FIG. 1, there is no simultaneous transmission determination function such as a wireless station compliant with the IEEE802.11a / b / g standard that is currently popular in neighboring houses. Even in an environment where the station is operating, the propagation environment between other stations can be estimated autonomously in the own station, and simultaneous transmission with high safety can be realized using the estimation result.

  In the present embodiment, the own station 11 intercepts the data packet d34 addressed to the other station 14 by the other station 13 and the ACK packet a43 returned from the other station 14 in response to the data packet d34. It is assumed that the two propagation loss estimation values L13 and L14 between the own station and other stations used for estimating the above are obtained. Other station signals used for obtaining the own-other station propagation loss estimation values L13 and L14 are not limited to this. For example, the own station 11 receives signals transmitted from the other stations 13 and 14 to other stations (not shown) and to the own station 11, performs transmission power estimation of the signals and measures received power at the own station 11, The inter-station propagation losses L13 and L14 may be estimated. In this way, in addition to the data packet d34 transmitted and received between the other stations 13 and 14 and the ACK packet a43 thereof, the propagation loss L13 and L14 between the own stations is obtained using the signals transmitted by the other stations 13 and 14. As a result, even during a period in which data transmission / reception is not performed between the other stations 13 and 14, the inter-station propagation loss L34 can be estimated and the allowable transmission power P1 for simultaneous transmission can be determined. Therefore, there may be a case where the simultaneous transmission attempt can be started earlier than when only the data packet d34 transmitted / received between the other stations 13 and 14 and the ACK packet a43 are used.

  In this embodiment, in order to simplify the explanation of the operation of the radio station 11, the data packet d34 addressed to the other station 14 by the other station 13 and the ACK packet a43 returned by the other station 14 in response to the data packet d34 It is assumed that the propagation loss L34 between other stations is estimated using the estimated propagation loss values L13 and L14 between the own station and other stations obtained by intercepting each time. However, due to factors such as received power measurement errors, temporary noise, and temporary propagation path fluctuations, it is estimated that the propagation loss between other stations and the propagation loss between other stations are estimated from only the other station signals that are intercepted once. Since the error may become large, the propagation loss between other stations is based on the average of the plurality of own-other-station propagation loss estimates L13, L14 for the other-station signals d34, a43 received a plurality of times recently. It may be desirable to estimate L34. As a method of taking an average of a plurality of times, a method of taking an average of a predetermined number of times, a method of taking an average within a predetermined time, normalizing after multiplying the immediately preceding average value by a forgetting factor of less than 1 and adding the latest estimated value Various averaging methods can be used such as

  As described above, in the inter-station propagation environment estimation method of the present embodiment, if two other station signals are intercepted and at least the transmission source stations of the two other station signals can be recognized, the two transmission source stations The other-station propagation loss between the other station and the own station is estimated, and the propagation loss between other stations is estimated based on the two estimation results. Therefore, by using the estimation method of the present embodiment, even when the other station is a station that does not have a simultaneous transmission determination mechanism such as a wireless station compliant with the IEEE802.11a / b / g standard, Estimate can be estimated.

  Furthermore, in the inter-station propagation environment estimation method of the present embodiment, the larger value of the two own-other-station propagation loss estimation results is estimated as the inter-station propagation loss, and the allowable transmission power is determined from the estimation result. To determine simultaneous transmission. As a result, the local station can try and implement simultaneous transmission with high “safety”.

  Here, “safety” means that there is little risk of hindering communication between other stations when simultaneous transmission with other stations is performed. In this embodiment, since the propagation loss between other stations is estimated using the larger value of the propagation loss between its own and other stations, safety can be increased. This will be described below. In general, the propagation loss Ltotal at the time of short-distance propagation such as indoors is expressed as a function of the attenuation amount due to the distance between stations and the transmission attenuation amount in a wall or the like existing between the stations. For example, ITU-RP. In 1238, it is recommended to use Equation 1 for indoor propagation loss estimation.

Ltotal = 20log10f + Nlog10d + Lf−28 (5)
f: Frequency used [MHz]
d: Distance between stations N: Distance attenuation coefficient Lf: Transmission attenuation Separate radio stations operate at the same frequency in the environment shown in FIG. 1, that is, in the surrounding area such as home A and adjacent house B and the next adjacent house. Since the same value is used for f and N in Equation 5, the difference between the own-other-station propagation loss L13, L14 and the other-station propagation loss L34 is the difference between the distances between the stations and between the stations. It is determined by the difference in transmission attenuation due to the shield.

  In the environment as described above, the other stations 13 and 14 operating in the peripheral house B are generally on the same side as viewed from the own stations 11 and 12 operating in the home A. That is, in FIG. 1, as can be understood from the length of the triangle formed by the own station 11, the other station 13, and the other station 14, the distance between the other stations is the longer distance between the other stations ( In FIG. 1, it is usually shorter than the distance between the own station 11 and the other station 14). Accordingly, the propagation loss L14 between the own station and the other station is usually the largest as the attenuation due to the distance between the stations. On the other hand, if the transmission attenuation due to the wall or ceiling in the same house that is normally assumed as a shield between other stations is less than or equal to the transmission attenuation due to the outer wall of the house that normally exists as a shield between the other stations, Conceivable. Further, considering the transmission attenuation amounts of the two own-other-station propagation losses L13 and L14, it is usually considered that the longer the propagation distance is, the easier the shield is interposed between them. Therefore, the propagation loss L14 between the own station and the other station is usually the largest for the transmission attenuation amount.

  Therefore, as in the present embodiment, when the inter-station propagation loss L34 is estimated as the larger value L14 of the inter-other-station propagation loss L, the actual value of the inter-station propagation loss L34 is + An error will usually occur. This + error is an error between the transmission power estimated value and the actual transmission power, a required CIR estimation error, fluctuations or variations in receiver characteristics of other stations, and interference signals or noises simultaneously with other stations It becomes a margin for various errors. Therefore, by performing simultaneous transmission determination using the inter-station propagation loss estimation method of the present embodiment, simultaneous transmission with high safety can be performed.

  In the first embodiment, as the method of estimating the propagation loss L34 between other stations, the larger one of the two own-other-station propagation loss estimated values L13 and L14 is estimated as L34. The method is not limited to this. For example, a larger value of L13 and L14 may be used as a reference value, and a value obtained by adding a predetermined error margin thereto may be used as the estimated value L34. By estimating in this way, it is possible to try a more secure simultaneous transmission. Or conversely, a larger value of L13 and L14 may be used as a reference value, and a value obtained by subtracting a predetermined error margin from the larger value may be used as the estimated value L34. By estimating in this way, the allowable transmission power from the own station 11 is increased, and thus the safety is lowered, but the possibility that communication between the own stations at the time of simultaneous transmission is established is increased.

  Further, the function of the inter-station propagation loss estimation unit 56 shown in FIG. 5 is reversed from the above-described embodiment, and the smaller value of L13 and L14 is used as a reference value, and a predetermined error margin is included in the reference value. A method of estimating the value obtained by adding or subtracting as the estimated value L34 may be used. When this method is used, compared with the case where the larger value of L13 and L14 is used as the reference value, the safety at the time of simultaneous transmission is reduced because the allowable transmission power is increased. There is a high possibility that communication will be established.

  Thus, there is a trade-off relationship between the safety when attempting simultaneous transmission and the possibility of establishment of communication between the local stations. It is most ideal to try the simultaneous transmission with the maximum allowable transmission power that satisfies the required CIR in the link between the other stations 11 and 12 in a good balance between the safety and the possibility of establishment of communication between the own stations. In order to approach this ideal, it is important not to increase the error margin more than necessary. Therefore, for example, when each element (transmission power P3, CIR 34, reception power R14, etc.) used for deriving the allowable transmission power by the estimation method of the present embodiment can be estimated with high accuracy, It is determined that the margin need not be so large, and the predetermined error margin is subtracted from the reference value. Conversely, when the accuracy of each element is poor, the predetermined error margin may be added to the reference value. When estimation is performed by adding or subtracting a predetermined error margin to the reference value in this way, for example, a variation (for example, a variance value) of a plurality of estimation results of the own-other-station propagation loss L13, L14 is obtained. For example, if it is larger (predetermined dispersion value), the propagation environment is unstable, and it is determined that the estimation accuracy of each element used for deriving the allowable transmission power is poor, and a predetermined error margin (for example, 3 dB) is added. If the variation is small (for example, smaller than a predetermined dispersion value), it may be determined that the propagation environment is stable and each element estimation accuracy is high, and a predetermined error margin (for example, 3 dB) is reduced. Also, for example, when effective information can be extracted from the other station signal to estimate the transmission power and required CIR of the other station, it is determined that the estimation accuracy of each element used to derive the allowable transmission power is high. A predetermined error margin may be added, and in the opposite case, the error margin may be reduced. Further, for example, when the difference between the own and other station propagation losses L13 and L14 is obtained and the difference is large, it is determined that the propagation environment is unstable and a predetermined error margin is added. The predetermined error margin may be reduced by determining that the propagation environment is stable. In this way, the balance between safety and the possibility of establishment of inter-station communication is established by estimating the propagation loss between other stations and the allowable transmission power by adjusting the predetermined error margin in consideration of the accuracy of each element. To improve simultaneous transmission.

<Modification 1>
In the first embodiment, the own-other-station propagation loss estimation unit 54 estimates the own-other-station propagation loss L13, L14 based on the equations 1 and 2, and the estimated values are determined by the other users. It is recorded in the inter-station propagation loss storage unit 55, and the own-other station propagation loss estimation values L13 and L14 are compared by the other-station propagation loss estimation unit 56 to estimate the other-station propagation loss L34.
L13> L14 ――― (Formula 6)
If Eq. 1 and Eq. 2 are substituted into Eq. 6, then P3-R31> P4-R41 --- (Eq. 7)
To establish. Also, as you can see by transforming Equation 7,
P3-P4> R31-R41 ――― (Formula 8)
Is established. Accordingly, the own station 11 estimates and records the two own and other station propagation losses L13 and L14 as in the first embodiment, and compares them to estimate the other station propagation loss L34. In place of 41, the other-station transmission power estimation values P3 and P4 and the received power measurement value R31 are replaced with the own-other-station propagation loss estimation unit 54 and the own-other-station propagation loss storage unit 55 shown in FIG. It is also possible to use a link information management unit 841 provided with a power storage unit 81 for storing R41 in the link information management unit. Then, the inter-station propagation loss estimation unit 82 refers to P3, P4, R31, and R41 stored in the power storage unit 81 to compare and determine whether or not Expression 7 or Expression 8 is satisfied.
L34 = P3-R31 ――― (Formula 9)
If not,
L34 = P4-R41 ――― (Formula 10)
In the allowable transmission power estimation unit 83,
R34 = P3-L34 ――― (Formula 3)
P1 = R34 + P4-R41-CIR34 --- (Formula 11)
The allowable transmission power P1 may be estimated based on Equation 3 and Equation 11.

<Modification 2>
Alternatively, as you can see by substituting Equation 3 into Equation 11,
P1 = P3-L34 + P4-R41-CIR34 --- (Formula 12)
It is expressed. L34 is estimated by Formula 9 or Formula 10 depending on whether Formulas 7 and 8 hold. That is, when Equations 7 and 8 hold,
P1 = R31 + P4-R41-CIR34 --- (Formula 13)
If not,
P1 = P3-CIR34 ――― (Formula 14)
Can be estimated. Accordingly, the local station 11 may include a link information management unit 941 as shown in FIG. 9 instead of the link information management unit 41. The link information management unit 941 does not have an inter-station propagation loss storage unit inside, and the inter-station propagation environment estimation unit 92 refers to P3, P4, R31, and R41 stored in the power storage unit 81 to obtain an equation. 7 or 8 is compared and determined, and the determination result is output to the allowable transmission power unit 93 as a comparison determination result signal s20. The allowable transmission power estimation unit 93 performs the expression 13 according to the comparison determination result signal s20. Alternatively, the allowable transmission power P1 is estimated based on Expression 14. As described above, the transmission power P3 and P4 of the other station and the reception powers R31 and R41 of the other station signal in the local station are compared without temporarily estimating the propagation loss between the other stations. It is also possible to estimate P1.

(Embodiment 2)
In the first embodiment, the transmission power of other stations, the propagation loss between other stations, the received power at other stations, etc. are estimated as the propagation environment between other stations, and the allowable transmission power that satisfies the required CIR is determined from the estimation result. Thus, simultaneous transmission is attempted with the determined power, and whether or not simultaneous transmission is possible is determined. In the present embodiment, it is assumed that the transmission power P1 of the own station 11 is determined to be a predetermined value regardless of the propagation environment between other stations.

  FIG. 10 is a diagram showing the configuration of the own station 11 in the second embodiment.

  In FIG. 10, portions different from the configuration of the first embodiment are a transmission power control unit 103, a link information management unit 104, a simultaneous transmission link management unit 105, and a transmission unit 107. The other signals and blocks having the same reference numerals as those in FIG. 4 are the same as those in the first embodiment, and thus the description thereof will be omitted. In the following, FIG. I will explain.

  The transmission control unit 103 determines the power of the transmission signal transmitted by the local station, and controls the transmission unit by giving transmission power control information s5. At the same time, the transmission power information s21 of the own station is given to the link information management unit 44.

  The link information management unit 104 extracts the header information of the packet transmitted from the demodulated data s2, and estimates and stores the propagation loss of the link that cannot be extracted from the demodulated data using the measured received power s3. Then, based on information such as the transmission power information s21 of the own station and the propagation loss estimated value between other stations, it is determined whether or not the link between other stations currently intercepted is a link that can be transmitted simultaneously, and the simultaneous transmission link The judgment information s22 and the intercepted packet address information s7 are output.

  The simultaneous transmission link management unit 105 stores link information that can be simultaneously transmitted based on the simultaneous transmission link determination information s22 and the address information s7, and from the address information s7, the simultaneous transmission link information stored in the past is stored. To determine whether the currently received link is a link that can be transmitted simultaneously. If it is determined that the link can be transmitted simultaneously, the simultaneous transmission timing signal s8 for performing simultaneous transmission and the packet length information s9 are output as in the first embodiment.

  In the transmission unit 107, the transmission unit 46 receives the transmission data s6, generates a packet, and generates and transmits a transmission signal s12. When following the CSMA procedure, the transmitter 107 performs carrier sense based on the received signal power s3 and determines whether or not transmission is possible. However, when a simultaneous transmission timing signal is received from the simultaneous transmission link management unit, a determination is made immediately to perform simultaneous transmission regardless of the carrier sense result, and the packet is determined based on the simultaneous transmission timing signal s9 and the packet length information s10. Generate and send.

  FIG. 11 is a diagram illustrating a configuration example of the link information management unit 104 in FIG. 11 differs from the link information management unit 44 of FIG. 5 in the first embodiment in that it includes a CIR determination unit 110 instead of the allowable transmission power estimation unit 58 of FIG. Is input, and the simultaneous transmission link determination information s22 is output by changing the allowable transmission power s4. Other signals and blocks with the same symbols as those in FIG. 5 are the same as those in the first embodiment, and thus the description thereof is omitted.

As in the first embodiment, the operation of the link information management unit 104 will be described by taking as an example the case where the own station 11 intercepts the data packet d34 of the other station 13 in the wireless system of FIG. The CIR determination unit 110 recognizes the transmission source address (address of the other station 13) and the destination address (address of the other station 14) of the other station signal included in the address information s7, and the other stations corresponding to the two recognized addresses. The inter-station propagation loss estimated value L34 is referred to from the inter-station propagation loss storage table 57. Then, when the reference value L34 is stored in the inter-station propagation loss storage table, the CIR determination unit 110 determines the inter-station propagation loss from the transmission power estimated value P3 of the other station 13 obtained from the transmission power information s12. By subtracting the estimated value L34, the received power R34 at the other station 14 of the currently transmitted data packet d34 is estimated. Next, the CIR determination unit 110 refers to the own-other station propagation loss estimated value L14 corresponding to the destination address from the own-other station propagation loss storage table of the own-other station propagation loss storage unit 55, and receives the estimated received power value. Between the R34, the own-other-station propagation loss estimated value L14, the required CIR estimated value CIR34 for the data packet d34 obtained from the required CIR information s13, and the transmission power P1 of the own station obtained from the transmission power information s21,
P1 ≦ R34 + L14−CIR34 —— (Formula 15)
Is determined, and the determination result is output as simultaneous transmission link determination information s22.

  FIG. 12 is a diagram illustrating a configuration example of the simultaneous transmission link management unit 105 in FIG. 11 is different from the simultaneous transmission link management unit 45 of FIG. 6 in the first embodiment in that it includes a simultaneous transmission storage unit 121 that receives the simultaneous transmission link determination information s22 instead of the simultaneous transmission storage unit 61 of FIG. However, a simultaneous transmission determination unit 123 is provided instead of the simultaneous transmission determination unit 63. Other signals and blocks with the same symbols as those in FIG. 6 are the same as those in the first embodiment, and thus the description thereof is omitted.

  The simultaneous transmission link storage unit 121, based on the simultaneous transmission link determination information s22, if the determination result can be transmitted simultaneously, the transmission source address and the destination address currently being received from the address information s7 can be transmitted simultaneously. Information is stored in a simultaneous transmission link storage table as shown in FIG.

  The simultaneous transmission determination unit 63 recognizes the link between other stations currently being received based on the address information s7, and refers to the simultaneous transmission link information table to determine whether or not simultaneous transmission is possible for the currently received transmission data. judge. When it is determined that simultaneous transmission is possible, the simultaneous transmission determination unit 63 outputs a simultaneous transmission timing signal s8 for performing simultaneous transmission.

  As described above, in the inter-station propagation environment estimation method of this embodiment, as in the first embodiment, two other-station signals are intercepted and at least the source station of the two other-station signals is recognized. If possible, the propagation loss between the own station and the other station that is the two transmission source stations is estimated, and the propagation loss between the other stations is estimated based on the two estimation results. Therefore, by using the estimation method of the present embodiment, even when the other station is a station that does not have a simultaneous transmission determination mechanism such as a wireless station compliant with the IEEE802.11a / b / g standard, Estimate can be estimated.

  Furthermore, in the inter-station propagation environment estimation method of this embodiment, the larger value of the two inter-station / other-station propagation loss estimation results is estimated as the inter-station propagation loss. When simultaneous transmission is attempted, it is determined whether or not the required CIR of another station is satisfied. As a result, the local station can perform simultaneous transmission determination with high “safety”. Therefore, by applying the above configuration to the own station 11 of FIG. 1, even when the transmission power is determined in the own station 11 regardless of the propagation environment between other stations, it is now widely used in adjacent houses. In an environment where other stations that do not have a simultaneous transmission determination function such as a wireless station conforming to the IEEE802.11a / b / g standard operate, the propagation environment between other stations can be estimated autonomously in the own station. By using the estimation result, a highly secure simultaneous transmission can be attempted as in the first embodiment.

(Embodiment 3)
FIG. 14 is a diagram showing a configuration of the own station 11 in the third embodiment. The configuration of the local station 11 in FIG. 14 is different from the configuration of the local station 11 of the first embodiment by the link information management unit 144. The other signals and blocks denoted by the same reference numerals as those in FIG. 4 are the same as those in the first embodiment, and thus description thereof will be omitted. In the following, description will be made focusing on parts different from those in the first embodiment.

  FIG. 15 is a diagram illustrating a configuration example of the link information management unit 144 in FIG. In FIG. 11, the difference from the link information management unit 44 of FIG. 5 in the first embodiment is an inter-station propagation loss estimation unit 156.

  Similar to the first embodiment, the inter-other-station propagation loss estimation unit 156 recognizes the source address and destination address of the other-station signal included in the address information s7, and the two corresponding to each of the two recognized addresses. The own-other-station propagation loss estimated value is referred to from the own-other-station propagation loss storage table of the own-other-station propagation loss storage unit 55. Then, the inter-other-station propagation loss estimation unit 156 calculates a difference value between the two own-other-station propagation loss estimated values. If the difference value is equal to or smaller than the predetermined value, it is assumed that the two other stations are operating in the same room of the house around the home A in FIG. Assume that the inter-station propagation loss estimated value s15 corresponding to the source address and destination address in the middle. On the other hand, when the difference value is larger than the predetermined value, the inter-station propagation loss estimation unit 156 currently receives the larger one of the two local-station propagation loss estimation values as in the first embodiment. Assume that the inter-station propagation loss estimated value s15 corresponding to the source address and destination address in the middle.

  As shown in FIG. 16, when the other stations 13 and 14 are arranged at a short distance from each other in the neighboring house B, the two signals d34 and a43 are transmitted from the own station 11 arranged at the home A with substantially the same propagation route. There is a high possibility of interception. When the two signals d34 and a43 propagate along substantially the same route, there is a high possibility that the attenuation amount due to the shielding object and the attenuation amount due to the distance until the two signals are intercepted by the local station 11 are approximately the same. Therefore, in the own station 11 of the third embodiment, the difference between the own station / other station propagation losses L13 and L14 between the other stations 13 and 14 and the own station 11 is smaller than a predetermined difference value by using this characteristic. Therefore, it is determined that the other stations 13 and 14 are arranged at a short distance from each other in the same room as shown in FIG. 6, and a predetermined propagation loss is set as an estimated propagation loss L34 between other stations. Here, as the predetermined difference value, for example, assuming the maximum distance (diagonal length of the room) on the plane of the average room size of a general house, the smaller value of the estimated propagation loss values between the two own stations Substituting into the predetermined propagation loss model equation, and calculating the propagation distance between its own and other stations by calculating backward, obtaining the propagation loss for the distance obtained by adding the assumed diagonal length to the estimated distance from the predetermined propagation loss model equation, The difference between the propagation loss and the propagation loss used for estimating the propagation distance between the own station and the other station may be a predetermined difference value. Further, as the predetermined propagation loss, a value obtained by determining the propagation loss with respect to the assumed diagonal length of the room from a predetermined propagation loss model formula may be used as the predetermined propagation loss.

  Here, the actual propagation loss between other stations is ITU-RP. Assuming that it matches the 2G band propagation loss estimation equation (Equation 16) recommended in 1238, an example of the inter-station propagation loss estimation method in this embodiment and its effect will be described using specific numerical values. .

Ltotal = 20log10f + 28log10d + 4n−28 (Equation 16)
f: Frequency used [MHz]
d: Distance between stations 4n: Transmission attenuation, n is the number of shielding objects For example, as shown in FIG. 16, the other stations 13 and 14 are installed in the same room with a transmission distance of 3 m and no shielding objects between them. It is assumed that the own stations 11 and 12 and the other stations 13 and 14 use a frequency of 2450 MHz. Further, assuming that the average room size of a general house is 3 m × 3 m and the diagonal length is 4 m, n = 0 and d = 4 are substituted into Equation 16, and a predetermined propagation loss is 57 dB. It is assumed that the propagation loss estimation values L13 and L14 between the own station 11 and the other stations 13 and 14 are estimated to be 70 dB and 71 dB, respectively. At this time, a smaller value (70 dB) of the own-other-station propagation loss estimated values L13 and L14 is substituted into the right side of a predetermined propagation loss model equation (Equation 16), and f = 2484, n = 2 By substituting the distance d between the stations by substituting 2 for the left side and calculating the distance d between the stations, the distance D13 between the own station and the other station is estimated to be 6 m. Similarly, when f = 2484 and n = 2 (assuming that the shielding object is two walls), and this estimated distance (6 m) and a distance (10 m) obtained by adding the assumed diagonal length (4 m) are substituted into Equation 16, Ltotal = 76 (dB). Therefore, in this case, the predetermined difference value serving as a criterion for determining whether or not the other stations 13 and 14 are close to each other is 6 dB (76 dB-70 dB). Therefore, as described above, when the two own-other-station propagation loss estimated values L13 and L14 are estimated to be 70 dB and 71 dB, respectively, the difference is 1 dB, and the difference is 6 dB or less calculated as a predetermined difference value. Therefore, the inter-station propagation loss L34 is estimated as a predetermined propagation loss 57 dB. From Equation 16, since the actual propagation loss L34 between other stations is 53 dB, the error between the actual L34 and the estimated value in this case is 4 dB. On the other hand, when estimated by the estimation method of the first embodiment, the larger value of L14 and L13 is the estimated value of L34, so 71 dB is the estimated value. In this case, the actual L34 and the estimated value The error is 18 dB. Therefore, the estimation method of the third embodiment can reduce the estimation error by 14 dB in this case as compared with the estimation method of the first embodiment.

  In the first embodiment, when estimating the propagation loss between other stations, the propagation loss between other stations is estimated from only the magnitude relationship between the propagation losses between the two other stations. A value that sufficiently includes a margin that takes into account is considered as an estimated propagation loss between other stations. However, when the distance between the other stations 13 and 14 is close and there is no shielding object as in the above-described example, the estimation error with respect to the actual propagation loss between other stations that becomes a margin considering the above error becomes too large. It can be considered. Therefore, as in the third embodiment, the estimation of the first embodiment is performed by estimating the propagation loss between other stations by using not only the magnitude relationship of the propagation loss between the two own stations but also the difference between them. By this method, it is possible to estimate the propagation loss between other stations with high accuracy.

(Embodiment 4)
FIG. 17 is a diagram showing a configuration of the own station 11 in the fourth embodiment. The configuration of the local station 11 in FIG. 17 is different from the configuration of the local station 11 of the first embodiment by the link information management unit 174. The other signals and blocks denoted by the same reference numerals as those in FIG. 4 are the same as those in the first embodiment, and thus description thereof will be omitted. In the following, description will be made focusing on parts different from those in the first embodiment.

  FIG. 18 is a diagram illustrating a configuration example of the link information management unit 174 in FIG. In FIG. 18, the difference from the link information management unit 44 in FIG. 5 in the first embodiment is an inter-station propagation loss estimation unit 186.

  Similar to the first embodiment, the inter-other-station propagation loss estimation unit 186 recognizes the source address and destination address of the other-station signal included in the address information s7, and two corresponding to each of the two recognized addresses. The own-other-station propagation loss estimated value is referred to from the own-other-station propagation loss storage table of the own-other-station propagation loss storage unit 55. Then, the inter-station propagation loss estimation unit 186 temporarily uses the larger value of the two inter-station propagation loss estimation values as the first inter-station propagation loss estimation value as in the first embodiment. Hold on. Further, the inter-station propagation loss estimation unit 186 internally stores a sensitivity table 1901 in which a transmission rate and a minimum reception sensitivity of a signal transmitted at the transmission rate are associated in advance as shown in FIG. When the transmission rate information of the other station signal currently received is included in s2, the minimum reception sensitivity at the destination station of the other station signal is estimated from the rate information, and the minimum reception sensitivity estimation value is subtracted from the transmission power value s12. The value is the second estimated propagation loss between other stations. Then, the inter-station propagation loss estimation unit 186 compares the temporarily stored first inter-station propagation loss estimation value with the second inter-station propagation loss estimation value and finally determines the smaller value. Is output as an inter-station propagation loss estimated value s15.

  In an environment where data transmission / reception is normally performed between the other stations 13 and 14, when the data packet d <b> 34 of the other station 13 is received by the other station 14, the received power R <b> 34 at the other station 14 is the minimum reception sensitivity of the other station 14. It is thought that it is received with the above size. Therefore, the inter-other-station propagation loss L34 is considered to be equal to or less than the second estimated inter-station propagation loss value obtained by subtracting the minimum reception sensitivity from the transmission power P3 of the other station 13. According to this logic, the inter-station propagation loss estimation unit 186 of the fourth embodiment uses the second inter-station propagation loss estimated value estimated in the same manner as in the first embodiment as the second inter-station propagation loss. If the estimated value is larger than the estimated value, the second estimated propagation loss between other stations is determined to be close to the actual propagation loss between other stations, and is finally output to the other-station propagation loss storage unit 57. Estimated propagation loss.

  Here, the actual propagation loss between other stations is ITU-RP. Assuming that it matches the 2G band propagation loss estimation equation (Equation 16) recommended in 1238, an example of the inter-station propagation loss estimation method in this embodiment and its effect will be described using specific numerical values. .

  For example, as shown in FIG. 20, the other stations 13 and 14 are installed in an environment having a propagation distance of 5 m and one shielding object (inner wall of the house) between them, and the own stations 11 and 12 and the other stations 13 and 14 are Assume that a frequency of 2450 MHz is used. In this case, the actual propagation loss L34 between other stations is assumed to be 63 dB according to Equation 16. The other station 13 is a wireless LAN terminal compliant with the 802.11g standard, and transmits data packet d34 at a transmission power of +15 dBm and a transmission rate of 54 Mbps, and communication with the other station 14 is established. That is, it is assumed that the ACK packet a43 from the other station 14 can also be received by the other station 13. Further, it is assumed that the own station 11 estimates that the own and other station propagation losses L13 and L14 are 76 dB and 83 dB, respectively. In this case, the first inter-station propagation loss estimated value estimated according to the inter-other station estimation method of the first embodiment is 83 dB, and the second estimated from the transmission rate information with reference to the sensitivity table of FIG. Since the inter-station propagation loss estimated value is 80 dB, the own station 11 of this embodiment finally estimates the inter-station propagation loss L34 to 80 dB. Therefore, the estimation error of the fourth embodiment can improve the estimation error by 3 dB in this case as compared with the estimation method of the first embodiment.

  In this way, not only the magnitude relationship of the propagation loss between the two other stations, but also the propagation loss obtained by estimating the minimum reception sensitivity at the destination station of the other station signal from the rate information included in the other station signal. Thus, by estimating the propagation loss between other stations, it is possible to estimate the propagation loss between other stations with higher accuracy than the estimation method of the first embodiment.

  In the fourth embodiment, as shown in FIG. 19, the minimum reception sensitivity of the data packet d34 is estimated from the correspondence table between the transmission rate and the minimum reception sensitivity. However, the present invention is not necessarily limited to this means. . For example, the same effect can be obtained by using a modulation scheme, modulation multi-level information and minimum reception sensitivity table instead of the transmission rate.

<Modification>
In the fourth embodiment, the own-other-station propagation loss L13 and L14 are estimated by the own-other-station propagation loss estimation unit 54 based on the equations 1 and 2, and the estimated values are determined by the other users. It is recorded in the inter-station propagation loss storage unit 55, and the own-other-station propagation loss estimation values L13 and L14 are compared by the other-station propagation loss estimation unit 56 to estimate the first other-station propagation loss L34 (1). From the transmission power P3 of the other station 13 and the minimum reception sensitivity S,
L34 (2) = P3-S ――― (Formula 17)
And estimate the second inter-station propagation loss L34 (2),
L34 (1)> L34 (2) ――― (Formula 18)
Is established, the final propagation loss L34 between other stations is expressed as L34 = L34 (2) ――― (Equation 19)
If not,
L34 = L34 (1) ――― (Formula 20)
Estimated.

L13> L14 ――― (Formula 6)
When the above holds, the equation 18 becomes L34 (1) = L13> L34 (2) --- (Equation 21)
It is expressed. If equation 21 holds, as is understood by substituting equation 1 and equation 17 into equation 21, S> R31 (Equation 22)
To establish. If equation 6 does not hold, equation 18 is
L34 (1) = L14> L34 (2) --- (Formula 23)
It is expressed. If equation 23 holds, as is understood by substituting equation 2 and equation 17 into equation 23, S> R41 + (P3-P4) ――― (equation 24)
Is established. Therefore, as in the modification of the first embodiment, the local station 11 may include a link information management unit 214 as illustrated in FIG. 21 instead of the link information management unit 1741. The link information management unit 214 replaces the own-other-station propagation loss estimation unit 54 and the own-other-station propagation loss storage unit 55 shown in FIG. 18 with other-station transmission power estimated values P3 and P4 and received power measurement values R31 and R41. Is stored in the power storage unit 81 in the inter-station propagation environment estimation unit 216 with reference to P3, P4, R31, and R41 stored in the power storage unit 81. First, whether or not Expression 7 or Expression 8 is established is compared, and if it is established, the minimum reception sensitivity S and the reception power R31 are compared according to Expression 22, and the larger value is estimated as the reception power R34 at the other station 14. To do. On the other hand, when Equation 7 or Equation 8 does not hold, the minimum reception sensitivity S is compared with the value obtained by adding the difference between the transmission power P3 and P4 to the reception power R41 according to Equation 24, and the larger value is determined as the other station. 14 is estimated to be the received power R34. Then, the estimated received power R34 is output to the allowable transmission power unit 93 as the comparison determination result signal s23. The allowable transmission power estimation unit 2193
P1 = R34 + P4-R41-CIR34 --- (Formula 11)
Based on the received power estimated value R34 obtained from the comparison determination result signal s23, the other station transmission power estimated value P4 obtained by referring to the power storage unit 81, the received power measured value R41, and the required CIR 34, the allowable value is given by Expression 11. The transmission power P1 is estimated. Thus, it is also possible to estimate the allowable transmission power P1 without once estimating the propagation loss between other stations.

(Embodiment 5)
FIG. 22 is a diagram illustrating the concept of the wireless communication system according to the fifth embodiment of the present invention. In FIG. 22, the difference from Embodiment 1 of the present invention is that not only the own station 11 but also the own station 12 estimates the propagation environment between the other stations 13 and 14 in the same manner as the own station 11, and The point is that the station 11 also estimates the inter-station propagation environment using the inter-station environment estimation result of the own station 12. Since the local station independent propagation environment estimation method in each local station is the same as in Embodiments 1 to 5 described above, description thereof is omitted. Below, the procedure which the own station 11 correct | amends the propagation loss estimated value between other stations of the own station 11 using the estimated propagation loss between other stations estimated by the own station 12 is demonstrated. In the following description, the inter-station propagation loss estimated values of the own stations 11 and 12 are denoted as L34 (11) and L34 (12), respectively.

  In FIG. 22, the own station 11 sends a request packet d <b> 12 s requesting the own station 12 to send the inter-station propagation environment estimation result estimated by the own station 12. Then, the local station 12 that has received the request packet d12s returns a response packet a21s including information on the inter-station propagation loss estimated value L34 (12) of the local station 12. The own station 11 extracts the propagation loss estimated value L34 (12) between other stations from the response packet a21s, and estimates the propagation loss estimated value L34 (11) between other stations of the own station 11 between other stations. Correction is performed using the value L34 (12).

  Various methods can be considered as a method of correcting the inter-station propagation loss estimated value of the local station 11 using the inter-station propagation loss estimated value estimated by the local station 11. When the station uses the inter-station propagation loss estimation method of the first embodiment, the inter-station propagation loss estimation values L34 (11) and L34 (12) are compared, and the smaller value is obtained. The final inter-station propagation loss estimated value L34 (11) may be used. This is because the inter-station propagation loss estimation method of the first embodiment is a highly secure estimation method, but on the other hand, there is a risk that an error margin is excessively large. Therefore, this risk is reduced by setting the smallest estimated value among the propagation loss estimates between other stations in a plurality of own stations as the final estimated propagation loss between other stations, thereby reducing the risk. Inter-station propagation loss estimation can be performed.

  FIG. 23 is a diagram illustrating a configuration of the link information management unit 234 of the local station 11 in the fifth embodiment. The own station 11 in the fifth embodiment is the same as the own station 11 in the first embodiment except that the link information management unit 44 in FIG. 4 is replaced with the link information management unit 234. Since the operation is the same, the illustration of the configuration of the own station 11 and the description other than the link information management unit are omitted. In FIG. 23, the difference from the link information management unit 44 of FIG. 5 in the first embodiment is that a propagation loss estimation correction unit 2357 is further provided.

  When the propagation loss estimation correction unit 2357 detects the address of the local station 12 as the transmission source address from the address information s7, the propagation loss estimation value L34 (12) between other stations is extracted from the demodulated data s2. Then, the inter-station propagation loss estimated value L34 (11) that has already been estimated and stored in the inter-station propagation loss storage unit 57 is referred to, and L34 (11) and L34 (12) are compared with each other. Is used as the final inter-station propagation loss estimated value L34 (11), and the value of L34 (11) in the inter-station propagation loss storage unit is updated.

  As described above, the inter-station propagation loss estimated value estimated by another local station (for example, the local station 12) is compared with the estimated value at the local station 11, and a small value is selected as the final estimated value. As a result, compared with the first embodiment, it is possible to reduce the risk of taking an error margin too large, and to perform more accurate estimation of propagation loss between other stations.

  Note that the request packet d12s and the response packet a12s described in the present embodiment are not necessarily dedicated packets. The same effect can be obtained by adding the data packet d12 transmitted by the own station, the ACK packet a12, the beacon packet, the existing transmission packet such as RTS, CTS, or the like.

  In the present embodiment, the inter-station propagation loss estimated value estimated by the two local stations is compared to correct the inter-station propagation loss estimated value. However, the local station 11 Even when there are three or more, it is possible to correct the estimated propagation loss between other stations in the same manner by changing the communication partner station of the own station that transmits the request packet. That is, in the present embodiment, the minimum value among the plurality of inter-station propagation loss estimated values is the final inter-station propagation loss estimated value.

  In this embodiment, the inter-station propagation loss estimation method for each station is the same as that in the first embodiment. Needless to say, this embodiment also applies to the third and fourth embodiments. It is possible to correct the estimated propagation loss between other stations.

  In this embodiment, the propagation loss estimated values between other stations estimated by a plurality of own stations are compared, and the minimum value is set as the final estimated propagation loss between other stations. The average value of the estimated loss values may be used as the final estimated inter-station propagation loss value. In this case, compared with the case where the minimum value is used, the risk that the error margin is excessively increased is increased, but on the other hand, the safety at the time of simultaneous transmission trial can be increased.

  In this embodiment, in order to correct the propagation loss estimated value between other stations by itself, the propagation loss estimated value between other stations itself is transferred between a plurality of own stations. The propagation environment parameter to be performed is not limited to this, and may be, for example, difference value information of two own-other-station propagation loss estimation values in each own station. For example, the local station 11 receives difference value information from a plurality of other local stations, and when the number of difference values equal to or less than a predetermined value is equal to or greater than a predetermined ratio (or a predetermined number), Only when the average value is equal to or smaller than the predetermined value, the predetermined propagation loss value may be used as the inter-station propagation loss estimated value in the same manner as the third embodiment other-station propagation loss estimation method. Also, for example, the local station 11 receives difference value information from a plurality of local stations, and only when the maximum value among the plurality of differential values is a predetermined value or less, estimates the propagation loss between other stations in the third embodiment. Similarly to the method, a predetermined propagation loss value may be used as an inter-station propagation loss estimated value. In this case, the security at the time of simultaneous transmission trial can be improved from the third embodiment. Hereinafter, this effect will be described in detail with reference to FIGS. 16, 24, and 25 showing examples of arrangement of the own station and other stations.

  As described in the third embodiment, as shown in FIG. 16, when the other stations 13 and 14 are arranged at a short distance from each other in the surrounding house B, the two signals d34 and a43 are the own station 11. There is a high possibility that the attenuation by the shield and the attenuation by the distance until interception will be almost the same. Therefore, in 3rd Embodiment, when the difference of the propagation loss between two own other station was small, it estimated that the other station was near. Here, for example, consider a case where the own stations 11 and 12 and the other stations 13 and 14 are in the positional relationship as shown in FIG. Similar to the case of FIG. 16, the own station 11 has a small difference between the propagation losses L13 and L14 between the own station and the other station, and it is determined that the other stations are close by the method of the third embodiment. it can. On the other hand, in the own station 12, since the shielding situation between the own station 12 and the other station 13 and the shielding situation between the own station 12 and the other station 14 are different, the difference between the propagation losses L23 and L24 between the two own stations is different. There is a high possibility that the estimation accuracy will be deteriorated because it is not less than a predetermined value and it cannot be determined that the other stations are close by the method of the third embodiment. Even in such a case, for example, the own station 11 and the own station 12 exchange the difference value of the propagation loss between the own station and the other station, and the number of difference values that are equal to or less than a predetermined value is a predetermined ratio (for example, In the case of more than half), it is determined that the other stations are close to each other, and the estimated loss value between the other stations is estimated as a predetermined propagation loss value in the same manner as in the method of the third embodiment, so that the estimation with high accuracy is possible. Can do. Here, for example, consider a case where the own stations 10, 11, 12 and the other stations 13, 14 are in the positional relationship as shown in FIG. In the case of FIG. 25, the distance between the other station 13 and the other station 14 is relatively far, but the distance between the own station 11 and the other station 13 and the shielding situation, and the distance between the own station 11 and the other station 14 and the shielding situation. And the difference between the propagation losses L13 and L14 between the two own stations is likely to be within a predetermined value, and the own station 11 independently determines the propagation loss L34 between the other stations by the method of the third embodiment. If estimated, the estimated value may be estimated to be smaller than the actual propagation loss between the other station 13 and the other station 14. Then, if the allowable transmission power is estimated from the estimated value and simultaneous transmission is attempted, there is a possibility that the communication of the other stations 13-14 is disturbed. On the other hand, the distance between the own station 12 and the other station 13 and the distance between the own station 12 and the other station 14 are approximately the same, but since the shielding situation is different, the difference between the propagation losses L13 and L14 between the two own stations is a predetermined value. There is a high possibility of exceeding. Further, although the shielding situation between the own station 10 and the other station 13 and that between the own station 10 and the other station 14 are approximately the same, the distance between the own station 10 and the other station 14 is quite different, so the difference between the two own-other station propagation losses L13 and L14 is predetermined. The possibility of exceeding the value is high. Even in such a case, the own station 11 obtains the difference value of the propagation loss between the own station and the other station estimated at each station from the other own stations 10 and 12, and becomes, for example, a predetermined value or less among the plurality of difference values. When the number of difference values is equal to or greater than a predetermined ratio (for example, half), it is determined that the other stations are close to each other, and the inter-station propagation loss estimated value is determined as the predetermined propagation loss value in the same manner as in the third embodiment. If this is estimated, the own station 11 can avoid erroneously determining that the other stations 13 and 14 are close to each other, and can perform highly accurate estimation.

  In this way, a certain own station obtains differential value information from other own stations, corrects the estimated propagation loss between other stations by itself and obtains the final estimated propagation loss between other stations. Further, the estimation accuracy can be further improved than in the third embodiment.

  Also, for example, the own station 11 receives difference value information from a plurality of own stations, and when the minimum value among the plurality of difference values is equal to or smaller than a predetermined value, the inter-station propagation loss estimation method of the third embodiment Similarly, the predetermined inter-station propagation loss may be used as the inter-station propagation loss estimated value. In this case, although the risk of estimating the propagation loss between other stations smaller than the actual increase from the third embodiment, the risk of excessively taking an error margin is further suppressed, and the simultaneous transmission opportunity can be increased. it can.

  In this embodiment, the propagation loss between other stations is passed between the own stations as the estimation target (propagation environment parameter) of the propagation environment between other stations, and the estimated value is corrected. The propagation environment parameter and the correction target are not limited to this. For example, the reception power estimation value R34 at the time of reception of the data packet d34 in the other station 14 estimated in each own station is passed, and the average value or the maximum of the plurality of reception power estimation values is passed. A trial of simultaneous transmission may be started with the value as the final received power estimation value R34.

  In this embodiment, the estimated propagation environment between other stations estimated by a plurality of local stations is compared and the correction of the estimation is performed. The inter-station propagation environment estimated value with high probability may be used as the final inter-station propagation environment estimated value.

  As information indicating the certainty, for example, time information at which estimation is performed may be used. For example, using this time information, the propagation loss estimated up to a predetermined time before the current time is used as a comparison target for correcting the estimated value, and the propagation loss estimated for a predetermined time or more in the past from the current time For example, a method of excluding from the comparison target for correcting the estimated value is considered because the probability is low. This makes it possible to perform estimation with higher accuracy even in an environment where the propagation path is likely to fluctuate with time.

  Further, as information indicating the probability, for example, a result of trying simultaneous transmission may be used. For example, the inter-station propagation environment estimation has been performed using the inter-station propagation environment estimation value, and the result is that the simultaneous transmission has been successful. The inter-station propagation environment estimation value is the next most likely inter-station propagation environment estimation value and the inter-station propagation environment estimation value. The propagation environment estimate is the most uncertain propagation environment estimate between other stations. Then, if there is the most probable estimated value among the multiple other-station propagation environment estimated values, the estimated value is corrected using only the estimated value, and the most reliable among the other-station propagation environment estimated values is obtained. If there is no probable estimated value and there is a next probable estimated value, the estimated value is corrected using only that estimated value, and if there is the most uncertain estimated value among the multiple other-station propagation environment estimated values, the estimated value It suffices to avoid the correction. As a result, it is possible to prevent an estimation error from being increased by using an uncertain estimated value, and to perform estimation with higher accuracy.

(Embodiment 6)
FIG. 26 is a diagram showing a configuration of the own station 11 in the sixth embodiment. The configuration of the own station 11 in FIG. 26 is different from the configuration of the first embodiment in the link information management unit 264. The other signals and blocks denoted by the same reference numerals as those in FIG. 4 are the same as those in the first embodiment, and thus description thereof will be omitted. In the following, description will be made focusing on parts different from those in the first embodiment.

  FIG. 27 is a diagram illustrating a configuration example of the link information management unit 264 in FIG. In FIG. 27, the difference from the link information management unit 44 of FIG. 5 in the first embodiment is that the inter-station propagation loss estimation unit 276 includes the inter-station maximum propagation loss setting unit 271.

  The maximum propagation loss setting unit 271 between other stations is set with a maximum propagation loss value between other stations assumed to operate around the own station (hereinafter referred to as a maximum propagation loss setting value). Similarly to the first embodiment, the inter-other-station propagation loss estimation unit 276 refers to the two own-other-station propagation loss L13 and L14 from the own-other-station propagation loss storage unit 55, and the larger of the two Is unconditionally regarded as the inter-station propagation loss L34, and the maximum propagation loss setting value set in the inter-station maximum propagation loss setting unit 271 is further referred to, and the larger of L13 and L14 When the value exceeds the maximum propagation loss setting value, the maximum propagation loss setting value is set as the propagation loss estimated value between other stations.

  In this way, the maximum propagation loss value between other stations assumed to operate in the vicinity of the own station is set in advance, and the propagation loss estimated value between other stations obtained by the estimation method of the above-described embodiments is set. If the maximum propagation loss setting value exceeds the maximum propagation loss setting value, the maximum propagation loss setting value is used as the inter-station propagation loss estimation value, thereby reducing the risk of excessive error margins and reducing the chance of simultaneous transmission. Can do.

  Various methods are conceivable as a method for setting the maximum propagation loss setting value. For example, a mode selection switch having a mode such as “condominium environment mode” or “detached house mode” is added to the own station 11, and the user selects the mode selection switch according to the usage environment, and the use is thereby performed. An appropriate maximum propagation loss setting value according to the environment may be set. Alternatively, the own station 11 may be provided with an interface for connecting to a personal computer, etc., and the user may start the software for setting the own station 11 and select a mode, or may directly input an appropriate propagation loss value. You may make it set. In addition, it is difficult for a general user who does not have knowledge about radio wave propagation to appropriately determine an appropriate propagation loss value. Therefore, when the software is started and the user directly sets an appropriate propagation loss value, the user does not directly input the propagation loss value, but the user observes the surrounding house in home A and places it in the surrounding house. It is only necessary to roughly estimate and input the maximum distance between other stations that can be installed (usually, the distance from one end to the other on the diagonal line of the surrounding house). Then, on the software side, the attenuation amount due to the distance is calculated from the input distance and a predetermined propagation loss model equation (for example, a calculation equation for free space loss), and a predetermined margin considering the attenuation amount due to shielding between rooms is calculated. The added value may be determined as an appropriate propagation loss value, and the determined value may be set in the inter-station maximum propagation loss setting unit 271. In addition, the layout of apartment houses such as apartments, housing complexes, and apartments is generally similar between adjacent rooms. It is considered that the maximum propagation loss between other stations in the adjacent room or the like in operation is approximately equal. Therefore, for example, a maximum propagation loss measurement mode is prepared in the software, and the local station 11 is located at a place where the user is assumed to have the largest propagation loss in the home (usually at the diagonal end in the home). Alternatively, after the own station 12 is temporarily installed, the maximum propagation loss measurement mode may be used to measure the propagation loss, and the measured value may be set in the maximum propagation loss setting unit 271 between other stations.

(Embodiment 7)
FIG. 28 is a diagram showing a configuration of the own station 11 in the seventh embodiment. The configuration of the own station 11 in FIG. 28 is different from the configuration of the first embodiment in the link information management unit 284. The other signals and blocks denoted by the same reference numerals as those in FIG. 4 are the same as those in the first embodiment, and thus description thereof will be omitted. In the following, description will be made focusing on parts different from those in the first embodiment.

  FIG. 29 is a diagram illustrating a configuration example of the link information management unit 284 in FIG. 29, the difference between the link information management unit 44 of FIG. 5 in the first embodiment is that the own-other station propagation loss estimation unit 54 is the propagation loss estimation unit 294, and the own-other station propagation loss storage unit 55 is different. The inter-station propagation loss storage unit 295 is replaced with an inter-station propagation loss estimation unit 56 in place of the inter-station propagation loss estimation unit 296, and a new inter-station distance estimation unit 297 is provided.

  The propagation loss estimation unit 294 recognizes the transmission source address included in the address information s7, and determines the inter-station propagation loss between the transmission source station and the own station of the signal currently being received as shown in FIG. Similar to the estimation unit 54, the estimation is made from the difference between the transmission power value s12 and the reception power value s3. Then, the address of own station 11 and the address of another station or the address of another own station (for example, own station 12) are used as address information s29, and the estimated propagation loss between the own station and other stations or the own station and other stations. The propagation loss estimated value between the stations (the propagation loss estimated value between the own stations) is set as the propagation loss estimated value s14, and s29 and s14 are output to the interstation propagation loss storage unit. Further, the propagation loss estimator 294 also receives the demodulated data s2, and the source address included in the address information s7 is the address of the other local station and is estimated by the other local station in the demodulated data s2. If a propagation loss estimation value is included, the propagation loss estimation between the own station and other stations is extracted and set as s14, and the addresses of other stations and other stations corresponding thereto are set as address information s29. s14 is output. Based on the address information s29 and the propagation loss estimated value s14, the inter-station propagation loss storage unit 295 obtains the addresses of the two stations and the estimated propagation loss between the two stations regardless of the own station or between the other stations. This is stored in the inter-station propagation loss storage table as shown in FIG.

  The inter-station distance estimation unit 297 recognizes the transmission source address and the destination address of the other station signal currently being received based on the address information s7, and four self-station addresses between the two other station addresses and the two own stations. By referring to the propagation loss between other stations and substituting the reference value into a predetermined propagation loss model equation, the distance between the four stations is estimated. Further, the inter-station distance estimation unit 297 also refers to the propagation loss estimated value between two own stations with reference to the own-other-station propagation loss estimated value, substitutes the reference value into a predetermined propagation loss model formula, and performs a reverse calculation. To estimate the distance between the two stations. Then, the inter-station distance is estimated based on the estimated total inter-station distance, and the inter-station distance estimation value is output to the inter-station propagation loss estimation unit 296.

  The inter-station propagation loss estimation unit 296 calculates the propagation loss by substituting the input inter-station distance estimation value into a predetermined propagation loss model formula, and uses the calculated value as the inter-station propagation loss estimation value s15. To the inter-propagation loss storage unit 57.

  Here, it demonstrates concretely using an example of the propagation loss estimation method between other stations in this embodiment, and FIG. As shown in FIG. 31, the distances D12, D13, D14, D23, and D24 between the stations described in FIG. 2 are represented as A, B, C, D, and E, respectively. An angle formed between the own station 11 and the own station 12 and between the own station 12 and the other station 14 is φ, and an angle formed between the own station 12 and the other station 13 and between the own station 12 and the other station 14 is θ. write. At this time, the distance D34 between other stations can be expressed by Equation 25 using the cosine theorem.

D342 = D2 + E2-2DE * cos θ ――― (Formula 25)
Furthermore, using the cosine theorem, Equations 26 and 27 hold for θ and φ.
θ + φ = cos−1 {(A2 + D2−B2) / (2AD)} (Equation 26)
φ = cos-1 {(A2 + E2-C2) / (2AE)} --- (Formula 27)
From equations 25, 26, and 27, the inter-station distance D34 can be expressed by equation 28.

D34 = (D2 + E2-2DEcos [cos-1 {(A2 + D2-B2) / (2AD)}-cos-1 {(A2 + E2-C2) / (2AE)}])-(Formula 28)
As can be seen from Equation 28, the inter-station distance D34 can be estimated if the four inter-station distances B, C, D, E and the inter-station distance A are obtained.

  Therefore, in the present embodiment, the distances B, C, D, and E between the own station and the other stations are set as ITU-RP. Using the propagation loss estimation formula (Equation 16) for 2G band recommended in 1238, the estimated values L13, L14, L23, and L24 between the own station and other stations are substituted for the left side of (Equation 16), and Assuming that the number of shields with other stations is two (n = 2), the calculation is performed by back calculation using Equation 16. Further, when the inter-station distance A is substituted for the inter-station propagation loss estimated value L12 in the left side of (Equation 16) and the inter-station distance D34 is estimated, Assuming that the system is installed in an environment in which no shielding object is present, the number of shielding objects is zero (n = 0), and is calculated by back calculation from Equation 16. The distances D34 are estimated by substituting the estimated distances A, B, C, D, and E into the equation 28. Then, the estimated distance D34 is substituted into (Expression 16), and the number n of shields interposed between other stations is set as a value corresponding to the estimated distance D34, and is estimated using (Expression 16). For example, when the estimated distance D34 is 4 m or less, the number n of shields according to the estimated distance D34 is about the size of a room of a general house. It may be assumed that an indoor wall exists and n = 1.

  Since the inter-station distances A to E estimated by the above-described method usually include an estimation error, the values in {} of Expressions 26 and 27 exceed 1 due to the error, and the estimation by Expression 28 is performed. An impossible situation can arise. In order to cope with such a situation, when the value in {} of Expressions 26 and 27 exceeds 1, for example, the value in {} of Expressions 26 and 27 is regarded as 1 and substituted into Expression 28. That's fine.

  By applying the configuration of the present embodiment to the own station 11 and the own station 12 in FIG. Even in an environment where other stations that do not have the simultaneous transmission determination function operate, it is possible to estimate the propagation distance and propagation loss between the other stations autonomously between the own stations.

  In this embodiment, the own station 11 also receives the signal from the own station 12 and the distance A between the own stations, and the propagation between the own stations from the difference between the transmission power value of the signal and the received power at the own station 11 Although the loss is estimated and determined, the method of determining the inter-station distance A is not limited to this. For example, the inter-station distance when estimating the inter-station distance is determined to be a predetermined value, and the user can The stations 11 and 12 may be temporarily installed according to the predetermined value, and then the distance between the other stations may be estimated. Alternatively, the own station 11 and the own station 12 may be appropriately installed, and the user may measure the distance between the own stations with a measure or the like, and input the distance measurement value using the initial setting software or the like. . As described above, by using the value obtained by actually measuring the distance between the own stations, it is possible to improve the accuracy of the distance estimation between other stations.

(Embodiment 8)
FIG. 32A is a diagram showing the basic concept of the inter-station propagation loss estimation method in the eighth embodiment. FIG. 32A is a diagram for explaining an actual usage method of the inter-station propagation loss estimation method in the eighth embodiment. Hereafter, the propagation loss estimation method between other stations in 8th Embodiment is demonstrated using Fig.32 (a) (b).

  As shown in FIG. 32A, in the eighth embodiment, the own station 10 and the own station 12 exist as other own stations that can communicate with the own station 11, and each of the own stations 10, 11, and 12 Own position information (x0, y0, z0), (x1, y1, z1), (x2, y2, z2). Then, the own stations 10 and 12 transmit their own position information and propagation loss estimated values L04 and L24 between the own station and the other station 14 to the own station 11. In the same manner as in the seventh embodiment, the own station 11 uses the own-other-station propagation loss estimated value sent from the own stations 10 and 12 and the own-other-station propagation loss L14 estimated by the own station 11 itself. Estimate the distances r0, r1, r2 between the other stations. Then, using the three-point surveying method, based on the estimated distance between the own station and other stations and the position information of each station, the radii r0, r1, r2 centered on the positions of the own stations 10, 11, 12 respectively. The intersection of the three circles is calculated, and the intersection is estimated as the position of the other station 14. Similarly, the position of the other station 13 is also estimated. Then, the distance between the other stations 13 and 14 is estimated from the estimated positions of the other stations 13 and 14, and in the same manner as in the seventh embodiment, the distance estimation value is substituted into a predetermined propagation loss model equation, The inter-station propagation loss L34 is estimated.

  In addition, since the propagation loss between the own station and the other station estimated by each of the own stations 10, 11, and 12 includes an error, the intersection of the three circles does not intersect one point, and a black square and a black triangle are shown in FIG. As indicated by the mark, there will usually be six intersections. Therefore, in the eighth embodiment, when the intersection does not intersect at one point due to the estimation error in this way, the center of three points closest to each other among the six intersections is estimated as the position of the other station. In FIG. 32 (b), the estimated positions of the other stations 13 and 14 are the centers of triangles each having three black squares and black triangle marks on the right side of the own station as vertices.

  In the inter-station propagation loss estimation method of this embodiment, if at least the source address of the other-station signal can be recognized, the inter-station propagation loss can be estimated in the same manner as in the first embodiment. The propagation loss between other stations can be estimated by transmitting / receiving the propagation loss estimated value and the position information of the own station. Therefore, by using the inter-station propagation loss estimation method of the present embodiment, even when the other station is a station that does not have a simultaneous transmission determination mechanism such as a wireless station compliant with the IEEE802.11a / b / g standard, Estimate propagation loss estimation between other stations.

  As described above, in the present embodiment, the position of the other station is estimated by basically using the three-point surveying method. However, the estimation method of the other station position is not limited to this, and various other station positions are estimated. The estimation method can be used. For example, the position of the other station may be estimated by applying the position calculation method disclosed in JP-A-2001-298664.

  An application method of the position calculation method disclosed in Japanese Patent Laid-Open No. 2001-298964 will be briefly described. In Japanese Patent Application Laid-Open No. 2001-298774, a base station (the own station of the present invention) notifies position information to a mobile station (another station of the present invention). The distance difference between the base station apparatus is calculated, and the position measurement means obtains the assumed distance of each base station from the estimated distance of the distance between one base station and the mobile station and the distance difference. The assumed position of the mobile station is calculated from the information, and this calculation is repeated until the difference between the distance obtained from the assumed position and the assumed distance becomes a predetermined value or less, and the position of the mobile station is estimated with high accuracy. In the present invention, since the other station assumes a wireless station such as 802.11a / b / g that does not have a function related to simultaneous transmission, the position of the other station is estimated on the own station side. Therefore, the own station 11 receives the position information from the two other own stations 10 and 12 and the phase information when the own stations 10 and 12 intercept the signal of the other station 14 and includes the own station 11. Further, the difference in distance between the other station 14 and each of the own stations 10, 11, 12 is calculated from the phase difference between the three own stations and the other station 14, and an arbitrary own station (for example, the own station 11) is set as an initial value setting. The estimated distance D14 between one of the stations and the other station 14 is assumed to be an assumed distance, the distance between the other stations 10, 12 and the other station 14 is also assumed from the assumed distance, and the assumed distance to each station is notified from each station. The assumed position of the other station 14 is calculated using the obtained position information, and the difference between the calculated distance between the own station and the other station 14 obtained from the calculated assumed position and the assumed distance becomes smaller than a predetermined value. The calculation is repeated while feeding back the calculated distance to the assumed distance, and the difference between the calculated distance and the assumed distance is predetermined. It estimates the presumed position of when it smaller and the position of other stations 14. As described above, even if the other station is a station that does not have a simultaneous transmission determination mechanism, it is possible to estimate the propagation loss between the other stations by estimating the position of the two other stations using the conventional disclosed technique. .

  In each of the above-described embodiments, the propagation loss model equation used is ITU-RP. The 2G band propagation loss estimation equation (Equation 16) recommended in 1238 has been described. However, the propagation loss model equation to be used is not limited to this, and the past or future indoor propagation experiment or indoor-outdoor It is of course possible to use other model formulas recommended as a result of radio wave propagation research such as inter-propagation experiments.

  Note that each functional block disclosed in the embodiment of the present invention is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include some or all of them.

  The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used. Alternatively, a configuration in which a processor is controlled by executing a control program stored in a ROM in hardware resources including a processor and a memory may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.

  INDUSTRIAL APPLICABILITY The present invention is useful as a wireless station peripheral propagation environment estimation method and a transmission control method in a wireless communication system in which a plurality of wireless stations exist. In particular, it is also useful when the surrounding wireless stations are wireless stations that do not have a simultaneous transmission determination function.

Wireless system conceptual diagram in the present invention The figure which showed the symbol showing the propagation environment parameter between the radio stations of the radio system in this invention, and each station The figure which shows the transmission sequence until the simultaneous transmission trial in Embodiment 1 of this invention. Configuration diagram of radio communication apparatus of own station in Embodiment 1 of the present invention Configuration diagram of the link information management unit in Embodiment 1 of the present invention Configuration diagram of simultaneous transmission link management section in Embodiment 1 of the present invention Explanatory drawing regarding the propagation table in the first embodiment The block diagram of the link information management part in the modification 1 of Embodiment 1 of this invention The block diagram of the link information management part in the modification 2 of Embodiment 1 of this invention Configuration diagram of radio communication apparatus of own station in embodiment 2 of the present invention Configuration diagram of link information management unit in Embodiment 2 of the present invention Configuration diagram of simultaneous transmission link management section in Embodiment 2 of the present invention Explanatory drawing regarding the propagation table in the second embodiment Configuration diagram of radio communication apparatus of own station in embodiment 3 of the present invention Configuration diagram of link information management unit in Embodiment 3 of the present invention The figure which shows the example of radio | wireless system arrangement | positioning for demonstrating the effect of Embodiment 3 of this invention. Configuration diagram of radio communication apparatus of own station in embodiment 4 of the present invention Configuration diagram of link information management unit in Embodiment 4 of the present invention Explanatory drawing about the propagation table in Embodiment 4 of this invention The figure which shows the example of radio | wireless system arrangement | positioning for demonstrating the effect of Embodiment 4 of this invention. The block diagram of the link information management part in the modification of Embodiment 4 of this invention Conceptual diagram of radio system in Embodiment 5 of the present invention Configuration diagram of link information management unit in Embodiment 5 of the present invention The figure which shows the example of radio | wireless system arrangement | positioning for demonstrating the effect of Embodiment 5 of this invention The figure which shows the example of radio | wireless system arrangement | positioning for demonstrating the effect of Embodiment 5 of this invention Configuration diagram of radio communication apparatus of own station in embodiment 6 of the present invention Configuration diagram of link information management unit in Embodiment 6 of the present invention Configuration diagram of radio communication apparatus of own station in embodiment 7 of the present invention Configuration diagram of link information management unit in Embodiment 7 of the present invention Explanatory drawing about the propagation table in Embodiment 7 of invention Explanatory drawing of the propagation loss estimation method between other stations in Embodiment 7 of this invention Explanatory drawing of the propagation environment estimation method between other stations in Embodiment 8 of this invention. (A) Conceptual diagram of wireless communication system using conventional CSMA (B) Transmission sequence diagram of wireless communication system using conventional CSMA Conceptual diagram of a conventional wireless communication system that determines whether simultaneous transmission is possible Conceptual diagram of a wireless communication system that points out the problems of conventional simultaneous transmission availability determination

Explanation of symbols

11-14, 101-104 Radio station 41 Demodulator 42 Received signal strength detector 43, 103 Transmission power controller 44, 841, 941, 104, 144, 174, 214 Link information manager 45, 105 Simultaneous transmission link manager 47, 107 Transmitter d12, d34 Data packet a21, a43 ACK packet

Claims (31)

A propagation environment estimation method in which a wireless station (own station) estimates propagation environment parameters between other wireless stations (other stations),
A first step of receiving a first other station signal transmitted by the first other station and estimating a first own-other station propagation environment parameter between the first other station and the own station; ,
A second step of receiving a second other station signal transmitted by the second other station and estimating a second propagation environment parameter between the second other station and the own station; ,
Based on the estimation result of the propagation environment parameter between the own station and the other station estimated in the first and second steps, the propagation environment between the other stations between the first other station and the second other station is determined by the own station. A propagation environment estimating method including a propagation environment estimating step between other stations for estimating a parameter; The propagation environment parameter is a propagation loss between the wireless stations,
In the first step, a first inter-other-station propagation loss is estimated from the transmission power of the first other-station signal and the received power when the own-station receives the second other-station signal. And
In the second step, from the transmission power estimated value of the second other station signal and the received power when the own station receives the second other station signal, the second inter-other station propagation loss is calculated. Estimate
In the inter-other-station propagation environment estimation step, estimating the inter-other-station propagation loss between the first and second other stations based on the first and second own-other-station propagation loss estimation results. The propagation environment estimation method according to claim 1. The first inter-other-station propagation environment parameter is a transmission power of the first other-station signal and a first reception power when the own-station receives the first other-station signal,
The second own-other-station propagation environment parameter is a transmission power of the second other-station signal and a second received power when the own-station receives the second other-station signal,
The inter-station propagation environment parameter between the first other station and the second other station is a reception power of the first other station signal in the second other station,
In the inter-other-station propagation environment estimation step, a transmission power difference value that is a difference between the transmission power of the first other-station signal and the transmission power of the second other-station signal, the first received power, and the first The received power difference value, which is a difference between the first received power and the second received power, or the first difference value, which is the difference between the transmission power of the first other station signal and the first received power, and the second received power. A comparison is made between a second difference value that is a difference between a transmission power of another station signal and the second received power, and the propagation environment parameter between the other stations is estimated based on the comparison result. Item 2. The propagation environment estimation method according to Item 1. 4. The propagation environment estimation method according to claim 2, wherein the transmission power is estimated from transmission power information contained in at least one of the first and second other station signals. In the inter-station propagation environment estimation step, the inter-station propagation loss between the first and second other stations based on the larger one of the first and second own-station propagation losses. The propagation environment estimation method according to claim 2, wherein: In the inter-other-station propagation environment estimation step, a value obtained by adding a predetermined error margin (including 0 or a negative value) to the larger one of the first and second own-other-station propagation losses, 6. The propagation environment estimation method according to claim 5, wherein an inter-station propagation loss estimation value between the first and second other stations is used. In the inter-station propagation environment estimation step, based on the difference between the first self-other station propagation loss and the second self-other station propagation loss, the other between the first and second other stations. 3. The propagation environment estimation method according to claim 2, wherein an inter-station propagation loss is estimated. In the inter-station propagation environment estimation step, the predetermined error margin is determined according to a difference between the first self-other station propagation loss and the second self-other station propagation loss. The propagation environment estimation method according to claim 6. In the inter-other-station propagation environment estimation step, when a difference between the first own-other station propagation loss and the second own-other station propagation loss is a predetermined value or less, a predetermined propagation loss value is The propagation environment estimation method according to claim 7, wherein the propagation loss estimation value between other stations between the first and second other stations is used. In the first and second steps, when the first and second other stations transmit the first and second other station signals, the transmission power estimation value and the own station are the first and second From the received power information when each other station signal is received, the first and second own-other-station propagation environment parameters are estimated as the first and second own-other-station propagation environment parameters, respectively.
In the inter-station propagation environment estimation step, the propagation loss between the first and second other stations is determined as the first inter-station propagation based on the estimation result of the first and second own-other-station propagation losses. Estimated as loss,
Based on the difference between the minimum reception sensitivity information contained in at least one of the first and second other station signals and the transmission power, the propagation loss between the first and second other stations is determined as the second other station. Estimated as inter-propagation loss,
Comparing the first inter-station propagation loss and the second inter-station propagation loss, the smaller value is the inter-other-station propagation loss estimated value between the first and second other stations. The propagation environment estimation method according to claim 2, wherein: In the inter-other-station propagation environment estimation step, a transmission power difference value that is a difference between the transmission power of the first other-station signal and the transmission power of the second other-station signal, the first received power, and the first The received power difference value, which is a difference between the first received power and the second received power, or the first difference value, which is the difference between the transmission power of the first other station signal and the first received power, and the second received power. The transmission power of the other station signal and the second difference value, which is the difference between the second received power, are compared, the inter-station propagation environment parameter is estimated based on the comparison result, and the result is Comparing the minimum reception sensitivity information contained in at least one of the first and second other station signals with the first inter-station propagation environment estimation value as the other-station propagation environment estimation value, the larger one The propagation environment parameter between other stations between the first and second other stations is estimated based on the value of Motomeko 3 propagation environment estimation method described. In the inter-other-station propagation environment estimation step, the own-station propagation environment parameter estimation value between the first and second other stations estimated by at least one or more other own stations is set as the other own-station propagation environment parameter estimation value. Between the first and second other stations estimated by the other own station, and between the first and second other stations estimated by the own station. The correction step of correcting the inter-station propagation environment parameter estimation value between the first and second other stations based on the inter-station propagation environment parameter estimation value is further included. The described propagation environment estimation method. In the correction step, an average value of the propagation environment parameter estimation value between other stations estimated by the own station and the propagation environment parameter estimation value between other stations estimated by the at least one other own station is calculated, 13. The propagation environment estimation method according to claim 12, wherein the average value is used as an inter-station propagation environment parameter estimation value between the first and second other stations. In the correction step, the maximum or minimum value of the inter-station propagation environment parameter estimation value estimated by the local station and the inter-station propagation environment parameter estimation value estimated by the at least one other local station 13. The propagation environment estimation method according to claim 12, wherein a propagation environment parameter between other stations between the first and second other stations is estimated based on the maximum value or the minimum value. In the inter-other-station propagation environment estimation step, the own-station uses at least one or more other own-stations to estimate the inter-other-station propagation environment parameters between the first and second other-stations. 4. Between the other stations between the first and second other stations estimated by the propagation environment estimation method according to claim 2, receiving estimation information from the other own station and using the other own station estimation information 4. The propagation environment estimation method according to claim 2, further comprising a correction step of correcting the propagation environment parameter estimated value. The other own station estimation information in the correcting step includes the first own and other station propagation environment parameters and the second own and other station propagation estimated by the other own station in the first and second steps. 16. The propagation environment estimation method according to claim 15, wherein the propagation environment estimation method is a difference value with respect to an environment parameter. In the correction step, a difference value between the first own-other-station propagation environment parameter estimated by the own station and the second own-other-station propagation environment parameter and the at least one other own station estimate An average difference value between the difference value between the first own-other-station propagation environment parameter and the second own-other-station propagation environment parameter is calculated, and predetermined when the average difference value is equal to or less than a predetermined value. 17. The propagation environment estimation method according to claim 16, wherein the propagation environment parameter value is an inter-other-station propagation environment parameter estimate value between the first and second other stations. In the correction step, a difference value between the first own-other-station propagation environment parameter estimated by the own station and the second own-other-station propagation environment parameter and the at least one other own station estimate The maximum difference value is calculated from the difference value between the first own-other-station propagation environment parameter and the second own-other-station propagation environment parameter, and the maximum difference value is a predetermined value. 17. The propagation environment estimation method according to claim 16, wherein a predetermined propagation environment parameter value is used as an inter-station propagation environment parameter estimation value between the first and second other stations in the following cases. In the correction step, a difference value between the first own-other-station propagation environment parameter estimated by the own station and the second own-other-station propagation environment parameter and the at least one other own station estimate The difference value which becomes the minimum among the difference values between the first propagation environment parameter between the own station and the other station and the second propagation environment parameter between the own station and the other station is calculated, and the minimum difference value is a predetermined value. 17. The propagation environment estimation method according to claim 16, wherein a predetermined propagation environment parameter is used as an inter-station propagation environment parameter estimation value between the first and second other stations in the following cases. In the correction step, when the number of difference values that are less than or equal to a predetermined value among the plurality of difference values estimated by the own station and other own stations is a predetermined value or more, a predetermined propagation environment parameter value is set to the first The propagation environment estimation method according to claim 16, wherein the propagation environment parameter estimation value between other stations between the second other stations is used. The said own station has memorize | stored previously the propagation loss maximum value between other stations, and the said between 1st and 2nd other station estimated by the propagation environment estimation method of Claim 2 in the said propagation environment estimation step between other stations If the estimated propagation loss between other stations is larger than the maximum propagation loss between other stations, the maximum propagation loss between other stations is corrected as the estimated propagation loss between other stations between the first and second other stations. The propagation environment estimation method according to claim 2, further comprising a correcting step. The propagation environment estimation method according to claim 21, wherein the maximum propagation loss between other stations is determined by a user observing the surrounding environment. The propagation environment estimation method according to claim 21, wherein the maximum propagation loss between other stations is determined by a user selecting a mode selection switch according to a use environment. The propagation environment parameter is a propagation distance between the wireless stations,
In the first step, the propagation distance between the first and second stations is estimated from the transmission power of the first other station signal and the received power when the own station receives the second other station signal. And
In the second step, from the transmission power estimated value of the second other station signal and the received power when the own station receives the second other station signal, the second own-other-station propagation distance Estimate
In the inter-other-station propagation environment estimation step, the own station obtains the first own-other-station propagation distance estimation value and the second own-other-station propagation distance estimation value estimated by the other own station. Receives and extracts a transmission signal from the station, and estimates the propagation distance between the own station and the other own station from the transmission power of the transmission signal from the other own station and the received power at the own station The first and second own-other station propagation distances estimated by the own station in the first and second steps and the first and second own-other station propagation distances estimated by the other own stations The propagation environment estimation method according to claim 1, wherein the inter-station propagation distance between the first other station and the second other station is estimated using the inter-station propagation distance. The own-other-station propagation environment parameter is position information of the other station, and the other-station propagation environment parameter is a propagation distance between other stations,
In the first step, the location information of the first other station is estimated by exchanging information among the plurality of local stations,
In the second step, the location information of the second other station is estimated by exchanging information among the plurality of local stations,
In the inter-other-station propagation environment estimation step, the first other-station and the first other-station from the first other-station position information and the second other-station position information estimated in the first and second steps. The propagation environment estimation method according to claim 1, wherein a propagation distance between other stations between two other stations is estimated. The location information of the first other station and the location information of the second other station are obtained from the two other own stations by the own station from the other own station and the other station by the other station. Phase information at the time of receiving a signal, and calculating the difference in distance between the other station and each own station from the phase difference between the three own stations including the own station and the other station, and an initial value As a setting, an estimated distance between any one of the own stations and the other station is assumed to be an assumed distance, a distance between the other own station and the other station is also assumed from the assumed distance, Calculate the assumed position of the other station using the position information notified from each own station, and the difference between the calculated distance from the other station obtained from the calculated assumed position and the assumed distance from the other station is The calculation is repeated while feeding back the calculated distance to the assumed distance until it becomes smaller than the specific value, and the difference between the calculated distance and the assumed distance is Propagation environment estimation method of claim 25, wherein the estimating the presumed position when smaller than value using the position calculating method of the position of the other stations. The propagation environment parameter is a propagation distance and a propagation loss between the wireless stations,
A propagation environment estimation method for estimating the propagation loss between other stations based on the propagation distance between other stations estimated by the propagation environment estimation method according to claim 24 or 25. The first radio station (own station) is capable of simultaneous transmission of a transmission link from the first other station to the second other station and a transmission link from the own station to the other own station. A method for estimating an allowable transmission power of a station, comprising:
The first wireless station estimates the inter-station propagation loss estimated value between the first other station and the second other station estimated using the propagation environment estimation method according to claim 2, and the first radio station. A reception power at the second other station is estimated from a transmission power of a signal transmitted from the other station to the second other station, and a predetermined required CIR and a received power estimation value at the second other station, The method of estimating the said permissible transmission power based on the said 2nd own-other-station propagation loss estimated value estimated using the propagation environment estimation method of Claim 2. The first radio station (own station) is capable of simultaneous transmission of a transmission link from the first other station to the second other station and a transmission link from the own station to the other own station. A method for estimating an allowable transmission power of a station, comprising:
The first wireless station receives, at the second other station, a signal transmitted from the first other station to the second other station estimated using the propagation environment estimation method according to claim 3. A method for estimating the allowable transmission power based on power, the second estimated propagation loss between other stations, and a predetermined required CIR. This is a transmission control method in which a first wireless station (own station) transmits a signal from the local station to another local station by overlapping with a time when a signal is transmitted from the first other station to a second other station. And
The local station estimates the allowable transmission power using the method according to claim 28 or 29, and the first transmission of the first other station addressed to the second other station with the estimated allowable transmission power. Allows simultaneous transmission of packets from the local station at the same time as the packet overlap, and allows simultaneous transmission based on the response result of the second other station or the presence / absence of a retransmission packet from the first other station with respect to the first transmission packet If transmission is determined and simultaneous transmission is determined to be possible, the first other station performs transmission at the same time after the next other station transmits a signal to the second other station. Control method. A propagation environment estimation device for estimating a propagation environment between radio stations,
Propagation environment estimation unit between own station and other stations for estimating propagation environment parameters between own station and other stations, and propagation between said own stations with respect to a plurality of other stations estimated by said own and other station propagation environment estimation unit A propagation environment estimation apparatus comprising: a comparison unit that compares environment parameters; and an inter-station propagation environment estimation unit that estimates inter-station propagation environment parameters between other stations other than the own station based on a comparison result of the comparison unit.

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