JP2005198118A - Mobile station device for narrow-band communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately give instruction, that it is difficult to utilize service to be provided by a narrow-band communication system caused by congestion of a radio communication path, to a user. <P>SOLUTION: This mobile station device is provided with: a frame control information detection means for detecting and extracting frame control information instructing configuration information of a communication frame and a use status of a communication slot, etc. transmitted from a base station device; and a congestion state judgment means for detecting a congestion state of radio communication from the frame control information detected by the frame control information detection means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a narrow-area wireless communication system that performs wireless communication between a mobile station mounted on a vehicle and a base station installed on a road, and particularly suitable for grasping a congestion state of a wireless communication path. It relates to station equipment.

Development of Intelligent Transport Systems (ITS), which integrates roads and vehicles, is underway to realize services aimed at improving safety, transport efficiency, and comfort. . In this system, realization of various services using wireless communication such as road-to-vehicle communication performed between a base station installed on the road and a mobile station mounted on a vehicle and vehicle-to-vehicle communication performed between mobile stations is considered. For example, road-to-vehicle communication is being applied to an automatic toll collection system for toll roads, and is also being developed for information provision services such as parking lots and drive-throughs.
One example of a road-to-vehicle communication system in this ITS is a dedicated short-range communication (DSRC) system that limits the communication area to a relatively narrow range of several meters to several tens of meters (for example, non-dedicated short-range communication). (See Patent Document 1). This DSRC method employs a synchronous time division communication method in which communication frames are time-divided into fixed-length sections called slots.

  FIG. 11 shows a configuration example of a communication frame. FIG. 11A shows an example of a configuration when the base station performs a full duplex communication operation, and FIG. 11B shows an example of a configuration when the base station performs a half duplex communication operation. The slots constituting this communication frame are broadly divided into communication slots and control slots, and messages for exchanging data between road vehicles so that communication with a plurality of mobile stations is possible in the communication slots. A plurality of data slots (MDS) are arranged. The control slot contains control information necessary for road-to-vehicle communication. The frame control message slot (FCMS) that stores the configuration information of the communication frame transmitted by the base station, the usage status of the communication slot, etc., and the mobile station Consists of an activation slot (ACTS) for requesting a communication connection to the base station.

  FIG. 12 shows an example of frame control information arranged in FCMS. The frame control information includes a frame synchronization signal, frame information and slot-specific control information, and an error detection code (CRC). The frame information includes a transmission channel control field (SIG) that stores characteristics of the physical layer, a base station An identification number field (FID) for storing an identifier, a frame configuration information field (FSI) for storing information relating to the frame configuration, a release timer information field (RLT) for suppressing reconnection from the mobile station for a certain period of time, the base station The service application information field (SC) stores an identifier for identifying a service provided by the. The slot-specific control information includes eight slot control information fields (SCI), and each control field corresponds to each slot as shown in FIG. Each SCI is composed of a control information subfield (CI) and a link address subfield (LID), and is placed in attribute information or MDS indicating whether a slot is assigned as MDS or ACTS by CI. The signal type and the like are indicated, and the address of the mobile station assigned to the slot is indicated by the LID. This makes it possible to determine the usage status of the slot such as to which mobile station the MDS is allocated.

  This system using the DSRC method is premised on spot communication in a limited communication area, and it is installed depending on the stop position of the vehicle when deploying the system to information providing services such as parking lots and drive-throughs. If the mobile station is out of the communication area, or is blocked or reflected by the influence of an obstacle even within the communication area, the quality of the radio section may deteriorate without obtaining sufficient electric field strength. There is. As described above, at a position where the quality of the wireless section is not sufficient, communication errors frequently occur, and a failure such as a significant delay in response from the service or inability to continue the service occurs. However, although such a failure in the communication path can be improved by moving the vehicle to a position where the quality of the wireless section can be ensured, there is no way for the user to judge it. In order to solve this problem, there is a method of determining the quality of a wireless section from the field strength and the retransmission rate of communication packets and instructing the user whether or not the stop position of the vehicle is appropriate (for example, see Patent Document 1).

JP 2003-218780 A

The Japan Radio Industry Association “Narrow Area Communication (DSRC) System Standard ARIB STD-T75”

However, a similar failure caused by the communication path may occur in the following cases. That is, when a plurality of mobile stations are simultaneously using the service within the communication area, the frequency of use of the communication slot in the communication frame increases, and the communication slot becomes congested. Further, when the number of connections with the mobile station increases and the degree of congestion increases, the communication opportunity per mobile station gradually decreases and the use bandwidth also decreases. In such a case, even if the mobile station is appropriately located in the communication area, the response from the service is delayed as the communication opportunity cannot be secured, and the service cannot be continued depending on the degree of congestion.
For such a failure, there may be a case where it is impossible to appropriately instruct the user that the service is difficult to use in a communication environment. This causes the user to make a mistake in determining whether the service can be continued. For example, when downloading a large amount of content, it takes a lot of time, which may impair the convenience of the user. .
The problem to be solved is to be able to appropriately instruct the user that the service provided by the DSRC system is difficult to use due to the congestion of the wireless communication path.

  In order to appropriately instruct the user that it is difficult to use the service due to congestion of the wireless communication path, the present invention provides, in the mobile station apparatus, the configuration information of the communication frame transmitted from the base station apparatus, Frame control information detecting means for detecting and extracting frame control information for instructing the usage status of communication slots, and the like, and a congestion state determining means for detecting a congestion state of wireless communication from the frame control information detected by the frame control information detecting means; Communication that cannot be used for communication of the local station existing in the communication frame obtained from the frame control information, with at least a period of one or more periods of the incoming communication frame as a measurement time in the congestion state determination means The number of slots is integrated within the measurement time to calculate the amount of congestion, and based on this, the determination result of the congestion state is generated and output. The main features of the door.

In the present invention, in order to appropriately instruct the user that the use of the service is difficult due to the congestion of the wireless communication path, the congestion state determination means performs at least one period of the incoming communication frame. Using the above time as the measurement time, the number of unused communication slots present in the communication frame determined from the frame control information is integrated within the measurement time to calculate the amount of congestion, and the congestion is based on this. The main feature is to generate and output a state determination result.
In the present invention, in order to appropriately instruct the user that the use of the service is difficult due to the congestion of the wireless communication path, the congestion state determination means performs at least one period of the incoming communication frame. Using the above time as the measurement time, the number of communication slots allocated to the local station present in the communication frame obtained from the frame control information is integrated within the measurement time to calculate the amount of congestion. The main feature is to generate and output the determination result of the congestion state.
In the present invention, in order to appropriately instruct the user that the use of the service is difficult due to the congestion of the wireless communication path, the congestion state determination means performs at least one period of the incoming communication frame. The above time is taken as the measurement time, the link address of the mobile station is detected from the frame control information, the total number of link addresses with different values detected within the measurement time is obtained as the congestion amount, and the congestion state is based on this. The main feature is to generate and output the determination result.

  With the above configuration, the mobile station device of the narrow-area wireless system of the present invention cannot use the mobile station device based on the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station device. Since the number of possible communication slots is measured, it can be determined that the greater the measured value, the greater the degree of congestion. Therefore, by presenting the determination result to the user using a display device or the like, the user can grasp the congestion state of the wireless communication path, so it can be determined whether the service should be continuously used or interrupted. It becomes like this. Also, by normalizing the measurement value based on the total number of search target slots that arrived within the measurement time, even if the configuration of the communication frame differs for each base station device, the determination result is always a value within a certain range. It will be possible to ask.

In addition, the mobile station device of the narrow-area wireless system of the present invention is assigned to any mobile station based on the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station device. Since the number of unused unused communication slots is measured, the smaller the measured value, the greater the degree of congestion can be determined. Therefore, by presenting the determination result to the user using a display device or the like, the user can grasp the congestion state of the wireless communication path, so it can be determined whether the service should be continuously used or interrupted. It becomes like this. In addition, by normalizing the measurement values based on the total number of slots to be searched from communication frames that should arrive within the measurement time, the determination result is always constant even when the communication frame configuration differs for each base station device. And the influence of the physical communication environment such as transmission errors can be reflected in the determination result.
In addition, the mobile station apparatus of the narrow-area radio system of the present invention can communicate with the communication station assigned to the mobile station based on the use status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station apparatus. Since the number of slots is measured, the smaller the measured value, the greater the degree of congestion can be determined. Therefore, by presenting the determination result to the user using a display device or the like, the user can grasp the congestion state of the wireless communication path, so it can be determined whether the service should be continuously used or interrupted. It becomes like this. In addition, by normalizing the measurement values based on the total number of slots to be searched from communication frames that should arrive within the measurement time, the determination result is always constant even when the communication frame configuration differs for each base station device. And the influence of the physical communication environment such as transmission errors can be reflected in the determination result. In addition, by normalizing the measurement value based on the total number of slots that should arrive within the measurement time, it is possible to digitize the band used by the own station.
In addition, the mobile station device of the narrow-area wireless system of the present invention is connected to the base station device from the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station device. Since the number of mobile stations can be measured, it can be determined that the greater the measured value, the greater the degree of congestion. Therefore, by presenting the determination result to the user using a display device or the like, the user can grasp the congestion state of the wireless communication path, so it can be determined whether the service should be continuously used or interrupted. It becomes like this.

  As described above, according to the present invention, there is an effect that it is possible to realize a mobile station apparatus of a narrow area communication system suitable for a user to grasp the congestion state of a wireless communication path.

  The configuration information of the communication frame transmitted from the base station device, with the purpose of appropriately instructing the user that the service provided by the DSRC system is in a state where it is difficult to use due to congestion of the wireless communication path, Frame control information detecting means for detecting and extracting frame control information for instructing the usage status of communication slots, and the like, and a congestion state determining means for detecting a congestion state of wireless communication from the frame control information detected by the frame control information detecting means; This is realized by providing a mobile station apparatus. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating an embodiment of a mobile station apparatus according to the present invention. FIG. 2 is a diagram showing an embodiment of a first determination procedure for determining a congestion state in the congestion state determination means 7 constituting the mobile station apparatus of the present invention. FIG. 3 is a diagram illustrating an example of a first congestion amount measurement procedure for measuring a congestion amount in the first determination procedure.
In FIG. 1, 1 is an antenna, 2 is modulation / demodulation means, 3 is FCM detection means, 4 is communication management means, 5 is communication control means, 6 is application processing means, 7 is congestion state determination means, and 8 is notification means. .

The mobile station apparatus shown in FIG. 1 demodulates the received signal received by the antenna 1 by the modulation / demodulation means 2 in order to detect a communication area formed by a base station apparatus (not shown), and does the demodulated signal include a communication frame? The FCM detection means 3 determines whether or not. The FCM detection means 3 detects the frame synchronization signal of the frame control information arranged in the FCMS from the demodulated signal obtained from the modulation / demodulation means 2. At this time, if the frame synchronization signal cannot be detected, the modulation / demodulation means 2 is controlled so that the frequency channel to be received is switched as appropriate so that the detection is continued. If it is detected, there is a transmission error in the control information following the frame synchronization signal. It is checked by using CRC multiplexed with frame control information. When the frame control information without transmission errors can be received a plurality of times, the FCM detection means 3 uses the communication management means 4 as the frame control information as a detection result of the communication area in order to attempt communication on the frequency channel. It operates to output to the congestion state determination means 7 every time it is detected. When receiving the frame control information, the communication management means 4 detects the frame configuration, slot attributes, etc. from the contents, and assigns the communication connection request signal to the ACTS to the communication control means 5 and is assigned to the own station. Instruct the timing to send / receive data to / from the MDS, and manage communication connection / disconnection status. The congestion state determination means 7 is instructed to start a state determination operation at the time of communication connection, and to instruct the end of the state determination operation at the time of communication disconnection. Operates to make connection notifications.
The communication control means 5 provides an interface for road-to-vehicle communication to the application processing means 6 that performs processing for using the communication service provided by the base station apparatus. When transmitting the communication data from the application processing unit 6, the communication control unit 5 performs transmission control for generating protocol data to which control information defining the processing procedure on the base station apparatus side serving as a transmission destination is added, When receiving communication data from a base station apparatus, control information is extracted from protocol data generated by a base station apparatus that is a transmission source, and reception control is performed. Further, the communication control unit 5 operates to exchange protocol data with the modem unit 2 at a timing instructed by the communication management unit 4 in order to exchange protocol data with MDS designated by the base station apparatus. . From the above, the mobile station apparatus operates to detect the communication area formed by the base station apparatus and perform wireless communication with the base station apparatus, so that the communication service provided there can be used. Become.

  The congestion state determination unit 7 determines the congestion state of the base station apparatus based on the frame control information output from the FCM detection unit 3 in accordance with the start and end instructions of the state determination operation from the communication management unit 4, and the notification unit The operation of outputting the determination result to 8 is performed. The notification means 8 converts the content of the determination result into information that can be intuitively recognized by the user. For example, there are a method of converting and displaying image information such as a columnar graph, character information, and the like, and a method of converting and generating sound such as a buzzer and voice. In the case of notification by display, the visibility may deteriorate if the variation of the determination result is large. In such a case, it is solved by performing smoothing processing such as moving average on the determination result. it can.

An example of the procedure of the congestion state determination unit 7 will be described with reference to FIG. Congestion state determination means 7 starts processing upon receiving a state determination operation start instruction from communication management means 4, and first sets a measurement time and starts a timer in step S1. Here, the measurement time set in the timer is set to a time longer than one cycle of the communication frame so that the frame control information can be received and processed at least once. In step S2, it is determined whether or not the measurement time has been exceeded from the state of the timer. If the timer has not timed out, the process proceeds to step S3. Step S3 is a determination process for waiting for the frame control information to be output from the FCM detection means 3. When the frame control information is received, the congestion amount T is measured in step S4. In the measurement processing of the congestion amount T in step S4, a slot corresponding to a condition set in advance for measuring the degree of congestion is searched from the CI and LID indicated by each SCI of the slot-specific control information of the frame control information. The quantity is counted in units of slots.
When the process of step S4 ends, the process proceeds to step S2, and a series of steps are repeated in the order of step S2, step S3, and step S4 until the timer times out, and the number of slots obtained in step S4 is determined within the measurement time. The amount of congestion T is obtained by integrating. If a timeout is detected in step S2, the process proceeds to step S5. In step 5, the obtained congestion amount T is output as a determination result S to the notification means 8. In step S6, an end instruction is determined from the communication management means 4. If there is no end instruction, the procedure from step S1 is repeated, and if there is an end instruction, the determination process ends.

Next, an example of the measurement processing procedure of the congestion amount T in step S4 of the first determination means is shown in FIG. In the measurement processing of this embodiment, since it can be determined that the station is congested if the number of slots that the station cannot use for communication within a unit time is large, the used slot that cannot be used by the station is congested as a search condition. Measure the degree of. First, the communication mode identifier (CM) and slot number information (SLN) stored in the FSI are read from the frame control information received in step S401. Here, CM is an identifier indicating whether the base station apparatus is operating in the full duplex communication mode or the half duplex communication mode.
SLN is an identifier for determining the communication frame length in the mobile station apparatus, and stores the number of slots following FCMS. (For example, in the example of FIG. 10A, the SLN stores 4 as the value, and in the example of FIG. 10B, the SLN stores 8 as the value.) In step S402, the communication mode is determined from the read CM value. In the case of the full duplex communication mode, the process of step S403 is performed. In the case of the half duplex communication mode, the process of step S404 is performed, and then the process proceeds to step S405.

  In full-duplex communication mode, separate measurements are possible because different bands are used for uplink communication from the mobile station device to the base station device and downlink communication from the base station device to the mobile station device. In services such as information provision, information is mainly downloaded, and it can be said that measuring the degree of congestion in downlink communication is effective as information provided to users. Therefore, in the slot search processing in the full duplex communication mode in step S403, the used slot is searched from the SCI corresponding to the downlink channel within the slot range indicated by SLN, and the number m of search slots is obtained. The used slot search is performed when the signal type identifier (ST) multiplexed in the CI of the MDS attribute indicates that there is a transmission signal from the base station, and whether or not the slot is assigned to the own station. This can be determined by determining from the address stored in the LID.

On the other hand, in the half-duplex communication mode, uplink communication and downlink communication use the same band, so slots occupied by other stations and ACTS correspond to used slots. Therefore, in the slot search process in the half-duplex communication mode in step S404, used slots are searched from all SCIs within the slot range indicated by SLN, and the number m of search slots is obtained. In addition, when the ST multiplexed to the CI of the MDS attribute indicates that there is a transmission or reception signal from the base station, the used slot search indicates whether or not the slot allocation is the local station. It is possible to make a determination based on the address stored in, and by determining the slot of the ACTS attribute.
In step S405, the number of search slots m obtained in step S403 or step S404 is added to the congestion amount T. From the above, the result of integrating the number of used slots within the measurement time can be obtained as the congestion amount T.

  According to the present embodiment, the number of communication slots that cannot be used by the own station is measured from the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station device. It can be determined that the greater the measurement value, the greater the degree of congestion. Therefore, by presenting the determination result to the user using the notification unit 8, the user can grasp the congestion state of the wireless communication path, so that it can be determined whether the service should be continuously used or interrupted. It becomes like this. Further, in this embodiment, paying attention to the fact that the time length of the slot of the DSRC system is fixed and the data stored in the slot is a fixed length, the integration of the data amount is replaced by the integration of the slot. As a result, the measuring means of the present embodiment does not need to actually measure the data multiplexed in each slot, so there is an advantage that the measurement process can be simplified.

FIG. 4 is a diagram illustrating an example of a second congestion amount measuring procedure for measuring the amount of congestion in the first determination procedure, and the others are the same as those of the first embodiment.
An example of a procedure for measuring the congestion amount T in step S4 of the first determination means is shown in FIG. In the measurement processing of the present embodiment, it can be determined that the station is congested when the number of unused slots that are not allocated to any mobile station within a unit time is small. The degree of congestion is measured using the slot as a search condition. First, the CM and SLN stored in the FSI are read from the frame control information received in step S411. In step S412, the communication mode is determined from the read CM value. In the case of the full duplex communication mode, the process of step S413 is performed. In the case of the half duplex communication mode, the process of step S414 is performed, and then step S415 is performed. Proceed to the process.

  In the slot search processing in the full duplex communication mode in step S413, the same search range as in the previous embodiment is targeted, and an unused slot is searched from the SCI corresponding to the downlink channel within the slot range indicated by SLN. The number m of search slots is obtained. The unused slot search is performed by determining the SCI that indicates that the signal type identifier (ST) multiplexed in the MDS attribute CI is empty (meaning that no slot is allocated to any mobile station). Yes.

In the slot search processing in the half-duplex communication mode in step S414, search for unused slots from all SCIs within the slot range indicated by SLN for the same search range as in the previous embodiment. The number of slots m is obtained. An unused slot can be searched for by determining the SCI indicating that the signal type identifier (ST) multiplexed on the MDS attribute CI indicates empty.
In step S415, the number of search slots m obtained in step S413 or step S414 is integrated with the congestion amount T. From the above, the result of integrating the number of used slots within the measurement time can be obtained as the congestion amount T.

  According to the present embodiment, the number of unused slots is measured from the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station apparatus. It can be determined that the degree of is large. Therefore, by presenting the determination result to the user using the notification unit 8, the user can grasp the congestion state of the wireless communication path, so that it can be determined whether the service should be continuously used or interrupted. It becomes like this. Further, as in the previous embodiment, the integration of the data amount is replaced by the integration of the slot, and the measurement means of this embodiment does not need to actually measure the data multiplexed in each slot. The advantage that the processing can be simplified is also obtained.

FIG. 5 is a diagram illustrating an example of a third congestion amount measurement procedure for measuring the amount of congestion in the first determination procedure, and the rest is the same as that of the first embodiment.
An example of the procedure for measuring the congestion amount T in step S4 of the first determination means is shown in FIG. In the measurement processing of this embodiment, if the number of slots that the own station can use within a unit time is small, it can be determined that the station is congested. Therefore, the degree of congestion is measured using the slot assigned to the own station as a search condition. . First, the CM and SLN stored in the FSI are read from the frame control information received in step S421. In step S422, the communication mode is determined from the read CM value, and in the case of the full duplex communication mode, the process of step S423 is performed. In the case of the half duplex communication mode, the process of step S424 is performed, and then step S425 is performed. Proceed to the process.

  In the slot search processing in the full-duplex communication mode in step S423, the slot assigned to the own station from the SCI corresponding to the downlink channel within the slot range indicated by SLN is targeted for the search range similar to the previous embodiment. To obtain the number m of search slots. In the search for the slot allocated to the local station, whether or not the allocation of the slot is the local station when the ST multiplexed in the CI of the MDS attribute indicates that the transmission signal from the base station exists. Can be determined from the address stored in the LID.

In the slot search processing in the half-duplex communication mode in step S424, search for slots assigned to the own station from all SCIs within the slot range indicated by SLN, targeting the same search range as in the previous embodiment. To obtain the number m of search slots. In the search for the slot allocated to the local station, whether or not the allocation of the slot is the local station when the ST multiplexed in the CI of the MDS attribute indicates that the transmission signal from the base station exists. Can be determined from the address stored in the LID.
In step S425, the number of search slots m obtained in step S423 or step S414 is integrated with the congestion amount T. From the above, the result of integrating the number of used slots within the measurement time can be obtained as the congestion amount T.

  According to the present embodiment, since the number of slots allocated to the own station is measured from the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station apparatus, the measured value It can be determined that the degree of congestion is larger as the value of is smaller. Therefore, by presenting the determination result to the user using the notification means 8, the user can grasp the congestion state of the wireless communication path, so that it can be determined whether the service should be continuously used or interrupted. It becomes like this. Further, as in the previous embodiment, the integration of the data amount is replaced by the integration of the slot, and the measurement means of this embodiment does not need to actually measure the data multiplexed in each slot. The advantage that the processing can be simplified is also obtained.

FIG. 6 is a diagram illustrating an example of a fourth congestion amount measurement procedure for measuring the amount of congestion in the first determination procedure, and the rest is the same as that of the first embodiment.
An example of the measurement processing procedure of the congestion amount T in step S4 of the first determination means is shown in FIG. In the measurement process of the present embodiment, it can be determined that the mobile station is congested when the number of mobile stations connected for communication is large. Therefore, the degree of congestion is measured using the link address appearing within the measurement time as a search condition. First, the SLN stored in the FSI is read from the frame control information received in step S431. In step S432, the link address address from the LID when the ST multiplexed from all SCIs within the slot range indicated by SLN to the MDS attribute CI indicates that there is a transmission or reception signal from the base station. Read. In step 433, the registered link addresses are excluded from the read link addresses and stored in the list. In step 434, the number of link addresses stored in the list is counted to calculate the number of mobile stations that are in communication connection and set as the congestion amount T.

  According to the present embodiment, the number of mobile stations connected to the base station device is measured from the usage status of the communication slot indicated by the frame control information detected and extracted from the communication frame transmitted by the base station device. Therefore, it can be determined that the greater the measured value, the greater the degree of congestion. Therefore, by presenting the determination result to the user using a display device or the like, the user can grasp the congestion state of the wireless communication path, so it can be determined whether the service should be continuously used or interrupted. It becomes like this.

FIG. 7 is a diagram showing an embodiment of a second determination procedure for determining a congestion state in the congestion state determination means 7 constituting the mobile station apparatus of the present invention. FIG. 8 is a diagram illustrating an example of a first reference amount measurement procedure for measuring a reference amount in the second determination procedure. Further, the first congestion amount measurement procedure is applied to the procedure for measuring the congestion amount in the second determination procedure, and the others are the same as in the previous embodiment.
An example of the procedure of the congestion state determination unit 7 will be described with reference to FIG. In this embodiment, the operations from Step 1 to Step 2, Step 3, and Step 4 are the same as in the previous embodiment. The procedure for measuring the amount of congestion in step 4 is the same as the first procedure for measuring the amount of congestion, and the amount of congestion T is obtained by integrating the number of communication slots that cannot be used by the local station.

  If a time-out is detected in step S2, the process proceeds to step S7, and the reference amount R is measured. In the measurement process of the reference amount R in step S7, a process for obtaining a reference value for normalizing the congestion amount T measured in step 4 is performed. In step S8, in order to obtain the determination result S, a process of normalizing the congestion amount T obtained in step S4 with the reference amount R obtained in step S7 is performed, and the determination result S obtained in step S8 is notified in step S5. Output to. In step S6, an end instruction is determined from the communication management means 4. If there is no end instruction, the procedure from step S1 is repeated, and if there is an end instruction, the determination process ends.

  Next, FIG. 6 shows an example of the procedure for measuring the reference amount R in step S5 of the second determination means. In the measurement process of the present embodiment, a process for obtaining the total number of slots that arrive within the measurement time as a reference value for normalizing the congestion amount T is performed. First, the SLN stored in the FSI is read from the frame control information received in step S501. In step S502, a process of adding the read SLN value to the reference amount R is performed. With the above processing, the total number of slots that arrive at the measurement time can be obtained.

  According to the reference amount measuring means of the present embodiment, the total number of slots to be searched that arrived within the measurement time can be obtained as the reference amount R. Therefore, even when the configuration of the communication frame differs for each base station device The result S can always be normalized to a certain range of values.

FIG. 9 is a diagram illustrating an example of a second reference amount measurement procedure for measuring a reference amount in the second determination procedure. Further, the second or third congestion amount measuring procedure is applied to the procedure for measuring the congestion amount in the second determination procedure, and the other steps are the same as in the previous embodiment.
The procedure for measuring the amount of congestion in step 4 in the present embodiment is the same as the procedure for measuring the amount of congestion in the second or the third, and the amount of congestion is obtained by integrating the number of unused slots or slots allocated to the own station. Find T. Next, FIG. 9 shows an example of the procedure for measuring the reference amount R in step S5 of the second determination means. In the measurement process of the present embodiment, a process for obtaining the total number of slots that should arrive within the measurement time as a reference value for normalizing the congestion amount T is performed. First, the SLN stored in the FSI is read from the frame control information received in step S511. In step S512, 1 is added to the read SLN value as the FCMS slot to obtain the slot length of the communication frame, and this is multiplied by the slot time length to obtain the period Tf. In step S513, the setting value Tm of the timer that manages the measurement time is read. In step S514, the timer set value Tm is divided by the communication frame period Tf to obtain the total number of frames F that should arrive within the measurement time. In step S515, the reference amount R is obtained by multiplying the total number of frames F by SLN. According to the above processing, the total number of slots to be searched can be obtained as the reference amount R from the communication frame that should arrive within the measurement time.

According to the reference amount measuring means of the present embodiment, the total number of slots to be searched can be obtained as the reference amount R from the communication frames that should arrive within the measurement time. Even if they are different, the determination result S can always be normalized to a value within a certain range. In addition, according to the reference amount measuring means of the present embodiment, the reference amount R is not calculated from the frame control information that actually arrives. For example, the electric field strength fluctuates, a transmission error occurs, and a communication frame is lost. Even when reception is not possible, the reference amount R can always obtain a constant value.
On the other hand, in the measurement of the amount of congestion T, since a frame control signal cannot be obtained if a communication frame is lost, the communication frame cannot be measured, but in this embodiment, an unused slot or a slot allocated to the own station is measured. Since it is the target, there is no effect on the measurement results. Conversely, when there are many missing communication frames, the value of the determination result S becomes small, and a result that can be determined that the degree of congestion is large can be obtained. Therefore, according to the reference amount measuring means of the present embodiment, the influence of the physical communication environment such as a transmission error can be reflected in the determination result S.

FIG. 10 is a diagram illustrating an example of a third reference amount measurement procedure for measuring a reference amount in the second determination procedure. Further, the third congestion amount measurement procedure is applied to the procedure for measuring the congestion amount in the second determination procedure, and the others are the same as in the previous embodiment.
The procedure for measuring the amount of congestion in step 4 in the present embodiment is the same as the third procedure for measuring the amount of congestion, and the amount of congestion T is obtained by integrating the number of slots allocated to the own station. Next, an example of the measurement processing procedure of the reference amount R in step S5 of the second determination means is shown in FIG. In the measurement process of this embodiment, a process for obtaining the total number of slots that should arrive within the measurement time as a reference value for normalizing the congestion amount T is performed. First, in step S521, the set value Tm of the timer that manages the measurement time is read. In step S522, the timer set value Tm is divided by the time length of the slot, and the total number of frames that arrive within the measurement time is obtained as the reference amount R. According to the above processing, the total number of slots including FCMS can be obtained as the reference amount R within the measurement time.

  According to the reference amount measuring means of the present embodiment, since the total number of slots that should arrive within the measurement time can be obtained as the reference amount R, the band used by the own station is digitized from the determination result S. Will be able to. That is, in the DSRC system, data arranged in the MDS has a fixed length. In the case of the ASK system with a transmission rate of 1024 kbps, data with an LPDU length of 65 octets is assigned to a slot length of 100 octets, and with the QPSK system with a transmission speed of 4096 kbps. Data having an LPDU length of 193 octets is assigned to a slot length of 400 octets, and the data utilization rate in each MDS is constant for each modulation scheme. Therefore, the bandwidth used can be easily calculated by multiplying the determination result S by the slot utilization rate and the transmission rate.

It is the figure which showed one Example of the structure of the mobile station apparatus. It is the figure which showed one Example of the 1st determination procedure in the congestion state determination means 7 of a mobile station apparatus. It is the figure which showed one Example of the 1st congestion amount measurement procedure in the 1st, 2nd determination procedure. It is the figure which showed one Example of the 2nd congestion amount measurement procedure in the 1st, 2nd determination procedure. It is the figure which showed one Example of the 3rd congestion amount measurement procedure in the 1st, 2nd determination procedure. It is the figure which showed one Example of the 4th congestion amount measurement procedure in a 1st determination means. It is the figure which showed one Example of the 2nd determination procedure in the congestion state determination means 7 of a mobile station apparatus. It is the figure which showed one Example of the 1st reference amount measurement procedure with respect to the 1st congestion amount measurement procedure. It is the figure which showed one Example of the 2nd reference amount measurement procedure with respect to the 2nd, 3rd congestion amount measurement procedure. It is the figure which showed one Example of the 3rd reference amount measurement procedure with respect to the 3rd congestion amount measurement procedure. It is the figure which showed the structural example of the communication frame. It is the figure which showed the structural example of the frame control information.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Modulation / demodulation means 3 FCM detection means 4 Communication management means 5 Communication control means 6 Application processing means 7 Congestion state determination means 8 Notification means

Claims (8)

In a mobile station device of a narrow area communication system that is mounted on a vehicle and performs wireless communication with a base station device installed on the road,
Frame control information detecting means for detecting and extracting frame control information for instructing the configuration information of communication frames transmitted from the base station apparatus, the usage status of communication slots, and the like;
A congestion state determination unit that detects a congestion state of wireless communication from the frame control information detected by the frame control information detection unit;
The congestion state determination means uses at least a period of one or more periods of an incoming communication frame as a measurement time, and determines the number of communication slots that cannot be used for communication of the local station existing in the communication frame obtained from the frame control information. A mobile station apparatus of a narrow area communication system, wherein the amount of congestion is calculated by integrating within the measurement time, and a determination result of a congestion state is generated and output based on the amount of congestion. In a mobile station device of a narrow area communication system that is mounted on a vehicle and performs wireless communication with a base station device installed on the road,
Frame control information detecting means for detecting and extracting frame control information for instructing the configuration information of communication frames transmitted from the base station apparatus, the usage status of communication slots, and the like;
A congestion state determination unit that detects a congestion state of wireless communication from the frame control information detected by the frame control information detection unit;
The congestion state determination means uses at least a period of one or more cycles of an incoming communication frame as a measurement time, and calculates the number of unused communication slots existing in the communication frame determined from the frame control information within the measurement time. A mobile station apparatus of a narrow-area communication system, characterized in that the congestion amount is calculated by calculating the congestion amount and the determination result of the congestion state is generated and output based thereon. In a mobile station device of a narrow area communication system that is mounted on a vehicle and performs wireless communication with a base station device installed on the road,
Frame control information detecting means for detecting and extracting frame control information for instructing the configuration information of communication frames transmitted from the base station apparatus, the usage status of communication slots, and the like;
A congestion state determination unit that detects a congestion state of wireless communication from the frame control information detected by the frame control information detection unit;
The congestion state determination means uses at least a time of one or more periods of an incoming communication frame as a measurement time, and determines the number of communication slots allocated to the own station existing in the communication frame obtained from the frame control information. A mobile station apparatus of a narrow-area communication system, characterized by calculating a congestion amount by integrating within a measurement time, and generating and outputting a determination result of a congestion state based on the amount of congestion. In a mobile station device of a narrow area communication system that is mounted on a vehicle and performs wireless communication with a base station device installed on the road,
Frame control information detecting means for detecting and extracting frame control information for instructing the configuration information of communication frames transmitted from the base station apparatus, the usage status of communication slots, and the like;
A congestion state determination unit that detects a congestion state of wireless communication from the frame control information detected by the frame control information detection unit;
The congestion state determining means detects a link address of a mobile station from the frame control information using at least a time of one period or more of an incoming communication frame, and a link address having a different value detected within the measurement time A mobile station apparatus of a narrow area communication system, characterized in that a congestion amount is obtained by calculating the total number of nodes, and a determination result of a congestion state is generated and output based on the amount of congestion. In the congestion state determination means according to claim 1,
From the frame control information detected by the frame control information detection means within the measurement time, the number of slots available for communication existing in the communication frame was obtained and accumulated, and the result could be actually received within the measurement time. A mobile station apparatus of a narrow area communication system, wherein the amount of congestion is normalized using the total number of slots as a reference amount. In the congestion state determination means according to claim 2 or 3,
Arranged within the measurement time from the number of slots available for communication existing in the communication frame from the frame control information detected by the frame control information detection means and the number of communication frames that should arrive within the measurement time A mobile station apparatus of a narrow-area communication system, characterized in that a total number of slots to be processed is obtained and the congestion amount is normalized using this as a reference amount. In the congestion state determination means according to claim 3,
The number of slots corresponding to the communication frame length is obtained from the frame control information detected by the frame control information detection means, and the total number of slots to be arranged within the measurement time from the number of communication frames that should arrive within the measurement time And the amount of congestion is normalized using this as a reference amount. In the congestion state determination means according to any one of claims 1 to 3,
When the communication mode indicated by the frame control information is a full-duplex communication mode, a slot used for downlink communication from a base station apparatus to a mobile station apparatus is a target for measuring the congestion amount. A mobile station apparatus for a narrow-area communication system.

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