JP5417286B2 - Relay station, center apparatus for controlling relay station, and mobile radio communication system - Google Patents

Description

  The present invention relates to a mobile radio communication technology, and more particularly, to a relay station that is located between a mobile terminal and a base station and relays a signal between the mobile terminal and the base station, and a relay station automatic selection technology.

  In a cellular mobile radio communication system, a plurality of base stations or antennas are distributed in various places. Among these multiple base stations or antennas, the base stations arranged adjacent to each other or the ranges covered by the antennas overlap to cover the entire wide area, and the mobile terminal has the highest signal quality. Controlled to connect to the station. A mobile radio communication system has a mechanism called a handover in which base stations connected to a mobile terminal are switched one after another as the mobile terminal moves, so that the radio communication can be maintained while the mobile terminal moves. it can.

  In such a mobile radio communication system, a signal transmitted from a certain base station or antenna is information directed to the base station or a plurality of mobile terminals connected to the antenna. Or, for communication of other mobile terminals that are not connected to the antenna, there is a case where influence as interference is given. Since the interference is a disturbance, the communication quality and throughput of the mobile terminal are deteriorated. Therefore, it is necessary to devise a method for appropriately controlling interference so that interference between the base station and the antenna does not occur.

  Such interference between base stations or antennas is mainly in a boundary region where adjacent antennas and adjacent base stations cover each other. In the boundary region, the signal power from the antenna and the base station is weak, and sufficient signal quality may not be ensured. As a configuration for supplying sufficient signal power to a place where such signal quality cannot be sufficiently ensured, IEEE 802.16, a standardization organization, actively discusses relay stations.

  The relay station is located between the mobile terminal and the base station, and is configured to relay a signal from the mobile terminal to the base station. Or it is the structure which relays the signal from a base station to a mobile terminal. In addition to supplying signal power to places with insufficient signal power as described above, installing relay stations in areas where signals from the base station are blocked by the presence of shielding objects and signals do not reach the mobile terminal Can be improved. Signals transmitted and received by the relay station between the mobile terminal and the base station can be used by dividing the same frequency in terms of time or by dividing the frequency. Further, it can be used by dividing it in terms of time while dividing it in terms of frequency.

  In addition, the relay station includes a single-hop connection method in which a radio link is directly established between a mobile terminal and a base station to transmit a signal, and a base station and a mobile terminal via a plurality of relay stations. There are multi-hop connection schemes connected. Patent Document 1 discloses a mobile communication system capable of determining a communication path capable of realizing high-speed communication in a multi-hop connection system relay.

WO2003 / 101132

IEEE802.16m System Description Document (4. Overall Network Architecture)

In order to eliminate places where signal power is insufficient or where signal power does not reach, it is necessary to arrange a large number of relay stations. Also, attention must be paid to interference between relay stations, and a wireless line design is required. However, the two events, that it is better to place a large number of relay stations and that the radio circuit design of each relay station is necessary, are relative to each other. It is difficult to arrange these relay stations while designing a wireless circuit.
In addition, even if a large number of relay stations can be arranged by designing a wireless circuit, the relay station does not always operate, but an appropriate relay station is selected from a large number of relay stations as required. It is necessary to let There are many base stations themselves, and there is a mechanism to select automatically to select and operate an appropriate relay station from among a large number of relay stations installed under those base stations. Indispensable. The present invention has been made to solve the above-described problems, and it is an object of the present invention to allow a large number of relay stations to be arranged without causing a problem of interference between relay stations without circuit design. And It is another object of the present invention to provide a mechanism for automatically selecting and operating an appropriate relay station from among a large number of relay stations.

  In order to solve the above problems, a relay station of the present invention transmits a signal received from a base station to a mobile terminal and transmits a signal received from the mobile terminal to the base station, and a mobile terminal Storing communication means operable in two modes of the transmission / reception function, means for acquiring position information, measurement means for measuring the quality of a signal received from the base station, and a predetermined signal quality threshold value. A relay station connected to the center station, and the control means compare the received signal quality from the base station measured by the measuring means with a threshold and Transmits position information and quality information to the center station, performs registration processing as a relay station, and sets the communication means as a mobile terminal until receiving an instruction signal instructing to operate as a relay station from the center station. It is created, upon receiving an instruction signal to operate as a relay station from the center station, in which the communication means so as to operate as a relay station.

  The center station of the present invention transmits two signals, a relay function for transmitting a signal received from the base station to the mobile terminal and a signal received from the mobile terminal to the base station, and a transmission / reception function as the mobile terminal. A plurality of relay stations operable in the mode, the position information of the relay stations included in the reports transmitted from the plurality of relay stations, the quality information of the signals received from the base stations to which the relay stations are connected, and the base station Or the location information included in the report transmitted from the mobile terminal connected to the relay station, the quality information of the received signal from the base station connected to the mobile terminal, and the quality information for determining the dead point A storage means for storing a threshold value and a threshold value for the distance from the dead spot and a control means are provided, and the dead spot is identified based on the position information of the report whose quality information is lower than the quality information threshold value. , Referring to the position information and quality information of the plurality of relay stations stored in the storage means, from among the plurality of relay stations, select a relay station whose distance from the dead point is below a predetermined distance threshold, Furthermore, the relay station with the best reception quality is selected from the selected relay stations, and when the relay station is operating as a mobile terminal, an instruction signal instructing to operate as a relay station is transmitted. Is.

  According to the present invention, it is possible to arrange a large number of relay stations without causing a problem of interference between relay stations without designing a line. Therefore, the cost, labor, and time for installing the relay station can be greatly reduced. In addition, it is possible to provide a mechanism for automatically selecting and operating an appropriate relay station from among a large number of relay stations.

1 is a configuration diagram of a cellular mobile radio communication system including a relay station. It is a figure explaining the relationship between a mode that a dead point generate | occur | produces, and a dead point and arrangement | positioning of a relay station. FIG. 5 is a communication sequence diagram when a relay station performs a relay operation to a mobile terminal having poor signal quality from a base station. FIG. 5 is a communication sequence diagram when a relay station performs a relay operation to a mobile terminal that does not receive signal power from a base station. It is a figure explaining allocation of the radio | wireless resource of a base station and a relay station in the mobile radio | wireless communications system using a TDD (Time Division Duplex) system. It is a figure explaining allocation of the radio | wireless resource of a base station and a relay station in the mobile radio | wireless communications system using a FDD (Frequency Division Duplex frequency division duplex) system. It is a figure explaining the structure of the mobile radio | wireless communications system in one Embodiment of this invention. It is a figure explaining the report transmitted to a base station from a relay station and a mobile terminal in one Embodiment of this invention. It is a block diagram explaining the structure of the relay station in one Embodiment of this invention, and the structure of the vending means combined with a relay station. It is a block diagram explaining the structure of the center station in one Embodiment of this invention. It is a flowchart explaining the registration process of the relay station used as a candidate started as a relay station. It is a flowchart which shows the processing content of the center station in one Embodiment of this invention. It is a flowchart explaining the operation | movement which selects the relay station which a center station should start from the relay station of a starting candidate. It is a figure explaining the data storage image of the mobile terminal of a center station, and a relay station management information table.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the basic configuration and operation of the relay station will be described with reference to FIG.

FIG. 1 is a configuration diagram of a cellular mobile radio communication system including a relay station 1.
The base station 3-1 or 3-2 is connected to a base station control device 4 that controls the base station. The base station 3-1 or 3-2 converts the signal received from the base station control device 4 into a radio signal and transmits it to the mobile terminal 2. When the mobile terminal 2 enters the shadow of a building or the like and the reception state is poor, the relay station 1 once receives a signal transmitted from the base station 3-1, and the signal is transmitted to the base station at an appropriate timing or frequency. The signal transmitted to the mobile terminal 2 by the 3-1 or 3-2 is relayed with low power. The mobile terminal 2 can receive the signal transmitted from the base station 3-1, that is, the information arrived from the base station control device 4 by receiving the relayed signal.

  The relay station 1 also supports signal relaying for signals in the upstream direction opposite to the arrows in FIG. In that case, the signal transmitted from the mobile terminal 2 to the base station 3-1 is also received by the base station 3-1, but is also received by the relay station 1. Since the relay station 1 is arranged at a short distance from the mobile terminal 2, the path loss is smaller than that of the base station. Therefore, the signal transmitted by the mobile terminal 2 can be received with good signal quality. Moreover, the relay station 1 is placed not indoors but outdoors, and is placed in a state where path loss with the base station is not large. Therefore, by appropriately amplifying the signal received from the mobile terminal 2 and transmitting it to the base station, it is possible to greatly increase the probability that the uplink signal will be successfully received.

Next, the relationship between the dead point and the arrangement of relay stations will be described.
FIG. 2 is a diagram for explaining the appearance of a dead spot and the relationship between the dead spot and the arrangement of relay stations.
In FIG. 2, there are a building 6-1 and a building 6-2 in the area covered by the base station 3, and signals transmitted from the base station 3 are shielded by the buildings 6-1 and 6-2, and the signal quality is This shows a state in which areas 7-1 and 7-2 are generated with poor quality. The symbol “x” indicates a dead point reported by the mobile terminal. In the present invention, the dead point is not a point where a signal from the base station cannot be received and the mobile terminal cannot communicate, and a point where the quality of the signal from the base station is not sufficient and communication is difficult to secure. .

  When considering the placement of the dead point and the relay station, it is effective to place the relay station at a location indicated by the relay station 1-1 or the relay station 1-2 close to the dead point. Therefore, the relay stations 1-1 and 1-2 work effectively to improve the area 7-1 or 7-2 where the signal quality is not good. On the other hand, since the relay station 1-3 is arranged in the dead spot 7-2, it is not effective in improving the area of the dead spot 7-2. Further, since the relay station 1-4 is arranged at a location far from the dead point 7-1 and the dead point 7-2, it is not useful for improving the area of the dead point 7-1 or the dead point 7-2.

  From this, when the relationship between the dead point and the arrangement of relay stations is arranged, the relay station has the difficult condition that (1) it is close to the dead point and (2) the relay station itself has good communication quality with the base station. It is necessary to satisfy. In the future, as the need to increase the communication speed increases, countermeasures for such dead points will become more important, and the arrangement of a large number of relay stations will be desired. In that case, (1) (2) It is necessary to arrange so that both conditions of the above are satisfied and interference between relay stations does not occur.

Next, the operation of the relay station will be described.
FIG. 3 is a sequence diagram when the relay station performs a relay operation to a mobile terminal having poor signal quality from the base station.
FIG. 4 is a sequence diagram when the relay station performs a relay operation to a mobile terminal to which signal power from the base station has not reached.

  In FIG. 3 and FIG. 4, a case where the base station supports HARQ (Hybrid Automatic Repeat Request) is described as an example. HARQ is a retransmission method when a received signal is decoded and an error check determines that reception of the signal has failed. In a receiver that employs HARQ, a signal in a soft decision state is stored in a memory even after decoding. If decoding fails, request retransmission from the sender. For the retransmitted signal, the signal accumulated in the past and the newly transmitted signal are obtained as the sum of the soft decision states, and the added information is decoded again. Since the signal received in the past and the retransmitted signal are added in the soft decision state, the likelihood of the information is improved and the possibility of decoding the information is increased compared to simple retransmission. Can do.

  With reference to FIG. First, the base station transmits a base station pilot (1000), and informs the mobile terminals and relay stations under control of the presence of the base station. In FIG. 3, although the base station pilot arrives at the relay station, it is indicated by a dotted arrow that the mobile terminal 2-1 receives it as a weak signal. The relay station also transmits a relay pilot (1001). The relay pilot is well received by the mobile terminal 2-1. Since the mobile terminal 2-1 has successfully received the relay pilot, the mobile terminal 2-1 transmits a relay request message to the relay station (1002). The relay station transfers the relay request message transmitted from the mobile terminal 2-1 to the base station (1003). The base station receives the relay request message, knows that it is advantageous that the signal transmission to the mobile terminal 2-1 is relayed by the relay station, and notifies the mobile terminal 2-1 to the relay station. Instruct to relay signal transmission. Therefore, the base station transmits a relay ACK message indicating that the relay request from the mobile terminal 2-1 is acknowledged to the relay station (1004). The relay station transmits to the mobile terminal 2-1 a relay ACK message indicating that the relay has been treated, to the mobile terminal 2-1 (1005). Thereby, the negotiation of the relay operation is completed.

  When the base station transmits a signal (information) to the mobile terminal 2-1 that has been determined to transmit a signal via the relay station according to the above procedure, the base station successfully decodes the information from the relay station. If an ACK is received, the HARQ is terminated. That is, the first transmission is performed (1006), but if an ACK is received from the relay station (1007), the corresponding information is not retransmitted. Although the first transmission is weak, if it has also reached the mobile terminal 2-1, the mobile terminal 2-1 transmits a NACK (1008). Since the mobile terminal 2-1 has already received the relay ACK message from the relay station, the NACK transmission partner is not a base station but a relay station. The relay station that has received NACK from the mobile terminal 2-1 transmits the same information for the second time to the mobile terminal 2-1 (1009). This time, transmission is from a nearby relay station, and the quality of the signal that can be received is good. Further, as the HARQ operation, the likelihood of information is increased by adding the first transmission (1006) received directly from the base station and the second transmission (1009) transmitted from the relay station in a soft decision state. The error correction ability can be greatly improved. Since the base station has already received the ACK from the relay station (1007), it uses the same timing and the same frequency as the second transmission (1009) and uses different information for another mobile terminal 2-2. Can be transmitted (1010). By this operation, the frequency utilization efficiency can be improved. The mobile terminal 2-1 transmits ACK (1011) to the relay station, and the mobile terminal 2-2 transmits ACK to the base station (1012).

  Similarly, FIG. 4 will be described. FIG. 4 shows a case where a signal transmitted from the base station does not reach the mobile terminal 2-1. First, the base station transmits a base station pilot (2000), and informs the mobile terminals and relay stations under control of the presence of the base station. Although the base station pilot reaches the relay station, it does not reach the mobile terminal 2-1 and is not received. The relay station also transmits a relay pilot (2001). The relay pilot is well received by the mobile terminal 2-1. Therefore, a relay request message is transmitted to the mobile terminal 2-1 to the relay station (2002). The relay station transfers the relay request message from the mobile terminal 2-1 to the base station (2003). The base station knows that the transmission to the corresponding mobile terminal is relayed by the relay station. The base station receives the relay request message from the mobile terminal 2-1, and transmits a relay ACK message indicating that the relay operation has been accepted to the relay station (2004). The relay station transmits, to the mobile terminal 2-1, a relay ACK message indicating that the relay has been treated to the mobile terminal 2-1 (2005). Thereby, the negotiation of the relay operation is completed.

  When the base station transmits a signal to the mobile terminal 2-1 determined to transmit a signal via the relay station according to the above procedure, the base station terminates HARQ if there is an ACK from the relay station. To work. That is, the first transmission is performed (2006), but if there is an ACK from the relay station (2007), the corresponding information is not retransmitted. When the first transmission does not reach the mobile terminal 2-1, the relay station performs the first transmission of the same information to the mobile terminal 2-1 (2009). It is a transmission from a nearby relay station, and an error-free communication can be acquired by the first transmission (2009). Although not shown, when this communication fails, the mobile terminal 2-1 transmits a NACK to the relay station. The relay station that has received the NACK performs the second transmission to the mobile terminal 2-1, and the mobile terminal receives the HARQ. At the timing and frequency at which this relay station performs the first transmission to the mobile terminal 2-1 (2009), the base station can transmit other information to another mobile terminal 2-2. (2010). ACK (2011) is transmitted from the mobile terminal 2-1 to the relay station, and ACK is transmitted from the mobile terminal 2-2 to the base station (2012).

Next, how to allocate radio resources when a relay station exists in the mobile radio communication system will be described.
FIG. 5 is a diagram for explaining radio resource allocation of a base station and a relay station in a mobile radio communication system using a TDD (Time Division Duplex) system.
FIG. 6 is a diagram for explaining radio resource allocation of base stations and relay stations in a mobile radio communication system using an FDD (Frequency Division Duplex) scheme.

  In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates frequency.

  FIG. 5A shows an example of radio resource allocation of a base station in a mobile radio communication system using the TDD scheme. The downlink communication line from the base station to the mobile terminal including the relay station uses the area 101. The uplink communication line from the mobile terminal to the base station uses the area indicated by 102. Since it is TDD, the uplink communication line and the downlink communication line are divided in the time domain.

  FIG.5 (b) has shown an example of the radio | wireless resource allocation of the relay station in the mobile radio | wireless communications system using a TDD system. The communication line from the base station to the relay station uses the area indicated by 103. The communication line from the relay station to the mobile terminal uses the area 201. The communication line from the relay station to the base station uses the area indicated by 104. The communication line from the mobile terminal to the relay station uses an area 202. By allocating radio resources in this way, the base station and the mobile terminal can communicate with the relay station by using a part of radio resources that have been used conventionally. In addition, by using time division, the relay station transmits information to the base station, and at the same time, it does not have to receive a signal from the terminal, thereby suppressing the influence of interference. it can. Therefore, the relay station can be configured in a small size.

FIG. 5 shows a case of TDD, but in the case of FDD, radio resource allocation as shown in FIG. 6 can be used. In FIG. 6, the horizontal axis represents time and the vertical axis represents frequency.
FIG. 6A is an example of allocation of radio resources of a base station in a mobile radio communication system using the FDD scheme. The base station uses two regions with different frequencies for communication with mobile terminals including relay stations. The downlink communication line from the base station to the mobile terminal uses the area indicated by 111. The uplink communication line from the mobile terminal to the base station uses the area 112.
FIG. 6B is an example of radio resource allocation of the relay station in the mobile radio communication system using the FDD scheme. The communication line from the base station to the relay station uses the area indicated by 113. The communication line from the relay station to the mobile terminal uses the area indicated by 211. The communication line from the relay station to the base station uses the area indicated by 114. The communication line from the mobile terminal to the relay station uses the area 212. By allocating radio resources in this way, the base station and the mobile terminal can communicate with the relay station using a part of the area that has been conventionally used. In addition, the relay station transmits information to the base station, and at the same time, it does not have to receive a signal from the mobile terminal, and the influence of interference can be suppressed. Therefore, the relay station can be configured in a small size.

(Example)
Hereinafter, specific examples of the present invention will be described.
Including the above points, the relay station has the following requirements and characteristics.
(1) Location must be fixed (2) Power supply is required (3) Many installed in urban areas (4) Vending means also require communication Also, for reasons described later, the following This is convenient.
(5) In the present embodiment, as a relay station provided with a configuration and a configuration convenient for the relay station, and the requirements and characteristics of the relay station listed in (1) to (5), which are lower than the surrounding buildings outdoors. The relay station is integrated with vending means including a vending machine. It will be described below that the present embodiment satisfies the above characteristics and requirements by integrating the vending machine including the vending machine and the relay station. In addition, by integrating vending machines, including vending machines, and relay stations, it becomes possible to install a large number of relay stations without causing interference problems between the relay stations. A mechanism for automatically selecting and operating a relay station will also be described below.

(1) Location must be fixed A relay station transmits a signal indicating that it is a relay station or an identification signal such as a relay pilot. If the relay station moves, the signal quality around the relay station becomes unstable, and the terminal must continue to search for the moving relay station. Therefore, the power of the mobile terminal is also consumed. For this reason, it is convenient that the location of the relay station is fixed. Since the location is fixed if the relay station is integrated with the vending means of the present embodiment, the requirement (1) can be satisfied.

(2) Power supply is required The relay station needs to transfer signals to the mobile terminal and must always communicate. Therefore, it is difficult to operate a battery-type configuration without a power source, and it is necessary to always supply power. If it is a relay station integrated with vending means, it is equipped with a control device for selling products and a power supply for cooling or keeping warm products such as juice, so this power supply is used as the power supply for the relay station Is possible. Therefore, if the relay station is integrated with the vending means of the present embodiment, the requirement (2) can be satisfied.

(3) Many relay stations located in urban areas are used as countermeasures for dead spots such as building shadows and indoors, and for places where radio waves do not reach. In the dead zone, the signal power from the base station is weakened, or the signal quality is deteriorated due to interference from the adjacent base station, so that highly efficient signal transmission cannot be performed. Under normal circumstances, investigate the signal quality of the dead point or the point where radio waves do not reach and its surroundings, design the radio line based on the survey result, and install the relay station to ensure good communication It is desirable to select a location, secure a location, and place a relay station at that location. However, considering the fact that signal quality frequently changes due to new buildings being built or demolished in the city, and that they must be deployed throughout the country, field surveys and radio circuit designs are conducted for each relay station. If this is done, an enormous amount of work and costs are required, so that it is practically impossible to conduct such investigations and wireless circuit designs.
A large number of relay stations integrated with the vending means of the present embodiment are arranged in the urban area because a lot of vending means are arranged especially in the urban area and places where people gather. Further, by selecting an appropriate one from among the methods described later, it is possible to operate while preventing interference between relay stations.

(4) Vending means also require communication When a relay station is arranged independently, the operator installing the relay station must undertake all costs. For example, even when installed on a utility pole, various costs such as the cost of placing the device on the utility pole, the rent of the utility pole, and the like are factors that hinder the installation of the relay station. However, the vending means itself also needs communication. Necessary communication is, for example, performing inventory management and informing the management source of a replenishment request if there is a shortage of products. Alternatively, it is also conceivable to receive advertisement information for product sales promotion from a communication line and display it on a display of a vending means. Therefore, by adding a few functions to the communication means required by the vending means and operating as a relay station, the operator who installs the relay station can greatly reduce the installation cost. In addition, operators of vending means can also benefit from providing a location as a relay station, for example, as a consideration given to operators who operate relay stations. Can be shared.

(5) In the description below in FIG. 5 and FIG. 6, the base station uses the same frequency for another movement while the relay station transmits a signal to the subordinate mobile terminal. It has been explained that radio resources can be allocated to communicate with a physical terminal. It is necessary to ensure that signals from a relay station to a mobile terminal under the relay station and the transmission of a signal from the base station to another mobile terminal can be received by those mobile terminals without interference. is there. For that purpose, it is important not only that the power transmitted by the relay station is weak, but also that the relay station is located lower than the surrounding buildings. Since the vending means are used by humans, the top plate of the vending means is located at a height of about 2 m. This height of about 2 m is lower than the surrounding building and higher than the position where the person has the mobile terminal. Even if the antenna is installed on the top plate of the vending means, it is a little over 2 m, and the antenna is located at a position lower than the surrounding buildings. Therefore, the signal transmitted from the antenna of the relay station integrated with the vending means is greatly attenuated when propagating across the building, and the interference hardly spreads. On the other hand, since the antenna of the relay station is often installed at a position higher than the height of the person, the antenna is installed at a position higher than the person communicating with the hand. Generally, the higher the antenna height, the better the reception sensitivity. Therefore, an antenna located at a height of about 2 m is in an environment where a signal from a base station can be received better than a mobile terminal held by a person.

(Configuration and operation of the entire mobile radio communication system of this embodiment)
FIG. 7 is a diagram for explaining the configuration of a mobile radio communication system including a relay station integrated in combination with the vending means of the present invention.

  The relay station of the present invention has a function of transmitting a signal from the base station 3-1 to the mobile terminal 2 and a function of transmitting a signal from the mobile terminal 2 to the base station 3-1, which are functions as a relay station. Have A base station control device 4 is connected to the base stations 3-1 and 3-2. A center station 5 is connected to the base station controller 4. The center station will be described with reference to FIG. The relay station will be described with reference to FIG.

FIG. 8 is a diagram for explaining a report transmitted from the relay station and the mobile terminal to the base station in the embodiment of the present invention.
The relay station and the mobile terminal transmit a report to the center station according to a timer, an instruction from the center, or a preset trigger. The reports from the relay station and mobile terminal include the CINR (Carrier to Interference-plus-Noise Ratio) measured using the location of the relay station and mobile terminal and the pilot signal of the base station. Contains information. The position information is measured using, for example, a signal received from GPS. Alternatively, position specifying means using a pilot signal transmitted from the base station may be used.

(Configuration and operation of center station)
FIG. 10 is a block diagram illustrating the configuration of the center station of this embodiment.
The role of the center station 5 is to manage a huge number of relay stations. The center station 5 obtains information on the dead point (position information on the dead point and CINR information on the dead point) from the mobile terminal via the base station 3-1 and the base station 3-2. An appropriate relay station is selected and relay operation is instructed to the selected relay station.

  The center station 5 shown in FIG. 10 has a network interface unit (NW I / F unit) 51 for connecting to the base station control unit 4, and the relay station and the mobile station via the base station control unit 4 and the base station 3. Communicating with the body terminal. The position information and CINR information of the relay station and mobile terminal included in the report from the relay station and mobile terminal are read by the CPU 52 and stored in the database unit (Data base) 53. The CPU 52 uses the information stored in the database to select a relay station according to the flow described below.

FIG. 12 is a flowchart showing the processing contents of the center station of the present invention.
First, the center station 5 receives a report from the mobile terminal (step 501). Next, the CINR included in the received report is compared with a threshold value to determine whether it is a dead point lower than the threshold value (step 502). If the condition is established and it is determined that the point is a dead point, the relay station located near the dead point is searched (step 503). As a result of the search, if it is determined that there is no active relay arranged near the dead point (step 504), the relay station information stored in the database is referred to and a new relay is started from the start candidate relay station. Search for stations. (Step 505).

  On the other hand, in step 502, if a relay station located near the dead point is searched and it is determined that there is an active relay (step 504), it is determined that some abnormality has occurred, and An alarm is issued (step 506).

FIG. 13 is a flowchart for explaining the operation of selecting a relay station to be activated from the activation candidate relay stations searched by the center station.
When the center station 5 selects a relay station to be activated from the activation candidate relay stations, the center station 5 first searches the database for activation candidate relay stations whose distance from the dead point is within a threshold (step 507). A relay station with the highest CINR is selected from the obtained relay candidate relay stations (step 508). Instructs the selected relay station to start activation as a relay station.
As described above, by selecting a relay station that is close to the dead point and has a good quality of the received signal from the base station from the activation candidate relay stations, an appropriate relay station can be selected and activated.

FIG. 14 is a diagram for explaining a data storage image of the management information table of the mobile terminal of the center station and the relay station.
The center station 5 manages the location information and CINR information of the mobile terminal included in the report reported by the mobile terminal. Further, the relay station location information and CINR information included in the relay station registration information reported by the relay station are managed. From the report reported by the mobile terminal, an area with a low CINR can be confirmed. When a report with a low CINR comes from a plurality of points close to each other, the area is determined as a dead point. Relay station registration information reported by the relay station selects a plurality of inactive relay stations that are close to the dead point according to the flow described in FIG. 12 and FIG. CINR is used to select the relay station with the best CINR as the relay station to be activated.

  Although not shown, information on whether the relay station is operating as a mobile terminal or as a relay station can be found in the management table of the relay station, whether the relay station is operating as a mobile terminal or operating as a relay station For example, it is conceivable to provide and manage a flag for discriminating whether or not it is.

(Configuration and operation of relay station)
FIG. 9 is a block diagram illustrating the configuration of the relay station of this embodiment and the configuration of the vending means combined with the relay station.
The relay station 10 shown in FIG. 9 is divided into a communication unit 9 and a vending unit 8.
In the default operation, the relay station integrated with the vending unit of this embodiment does not operate as a relay station, and the communication unit 9 operates as a simple terminal. When the relay station integrated with the vending means of the present embodiment receives a message instructing to operate as a relay station from the center station, the relay station shifts to operation as a relay station.

<Operation of relay station as terminal>
First, the case of operating as a simple terminal, which is the default operation, will be described.
The communication unit 9 includes a radio circuit unit (RF) 91 that transmits and receives signals to and from a mobile terminal and a base station, a baseband unit (BB) 92 that performs baseband signal processing, and a CPU 93 that controls various controls of the communication unit 9. And a network interface unit (NW I / F) 94 connected to the vending means 8. Moreover, it has the GPS unit part (GPS) 95, and the GPS unit part (GPS) 95 analyzes the supplied GPS signal, reproduces the current position and time information, and reproduces the clock. The obtained information is supplied to the CPU 93 and the like.

Processing of the downlink communication line when operating as a terminal will be described.
The radio circuit unit (RF) 91 converts a signal received by the antenna into a baseband signal. Further, the GPS signal received by the antenna is supplied to the GPS unit (GPS) 95.
The baseband unit (BB) 92 performs signal processing on the baseband signal generated by the radio circuit unit (RF) 91, and performs CINR measurement and decoding processing. The decrypted information is supplied to the CPU 93. Here, when decoding fails, likelihood information (or soft decision information) before decoding is stored in the memory. For the signal retransmitted by HARQ, the information accumulated in the memory and the newly received information are added, and decoding is attempted again. Such signal processing related to HARQ is performed in the baseband unit (BB) 92. When decoding is successful, ACK information is generated at an appropriate timing and an appropriate frequency, and is sent to the radio circuit unit (RF) 91. The radio circuit unit (RF) 91 converts the ACK information into a radio frequency and transmits a signal from the antenna. A signal that has been successfully decoded is transmitted to the mobile terminal. Information transmission to the mobile terminal is instructed at the timing and frequency determined by the CPU 93. The baseband unit (BB) 92 generates a baseband signal directed to the mobile terminal at the instructed timing and frequency. The generated baseband signal is sent to the radio circuit unit (RF) 91, and the signal is transmitted from the antenna.

The processing of the uplink communication line when operating as a terminal will be described.
First, a baseband signal is generated in the baseband unit (BB) 92 at an appropriate timing and an appropriate frequency according to an instruction from the CPU 93. The generated signal is sent to a radio circuit unit (RF) 91, converted into a radio frequency, and transmitted from an antenna.
In the case of terminal operation, information received from the base station is passed to the vending means 8 via the network interface unit (NW I / F) 94. The vending means 8 is a merchandise management unit (product management) that stores information for managing the inventory of merchandise communicated with the CPU 81 that controls various controls of the vending means 8 and the communication means 9 connected to the vending means 8. 83 and a display 82 for displaying advertisement information communicated through the communication means 9 connected to the vending means 8. The CPU 81 of the vending means 8 processes the obtained information and displays the information on the display 82, for example. Alternatively, an inventory management report is created according to the passed information. Therefore, the product management unit (product management) 83 is accessed to investigate the purchase status of the product. The investigation result is transferred to the communication means 9 via the network interface unit (NW I / F) 94, and wireless processing is performed to transmit information to the base station.

<Activation of relay station operation>
FIG. 11 is a flowchart for explaining the registration process of a relay station that is a candidate for activation as a relay station.
The relay station measures CINR of the signal received from the base station (step 401), and the relay station compares the CINR measurement result with a threshold value (step 402). If the CINR measurement result is higher than the threshold value and the condition is satisfied, relay station registration information including the CINR and position information is transmitted to the center station (step 403). If the threshold condition is not satisfied in step 402, the relay station registration information is not transmitted to the center station (step 404).

  In FIG. 9, the report is created by the CPU 93 and reported to the center station via the base station through signal processing of the uplink communication line. The center station selects a relay station based on dead point information and notifies the selected relay station of a message instructing to operate as a relay station. The relay station receives an instruction from the center station via radio. When the CPU 93 receives the relay station operation instruction, the CPU 93 starts operation as a relay station.

<Relay operation>
The radio circuit unit (RF) 91 converts a signal received by the antenna into a baseband signal. The baseband unit (BB) 92 performs signal processing on the baseband signal generated by the radio circuit unit (RF) 91, and performs CINR measurement and decoding processing. The decrypted information is supplied to the CPU 93. The obtained information is once stored in the memory, and then transmitted to the terminal according to an instruction from the CPU. When the form of the relay is the form shown in FIG. 3, transmission is started by receiving a NACK from the terminal. When the form of the relay is the form shown in FIG. 4, the CPU determines the situation with other communications, performs scheduling, and transmits a signal to the mobile terminal using an appropriate frequency at an appropriate timing. . At that time, a baseband signal is generated in the baseband unit (BB) 92 at an appropriate timing and an appropriate frequency according to an instruction from the CPU 93. The generated signal is sent to a radio circuit unit (RF) 91, converted into a radio frequency, and transmitted from an antenna.

  The relay station 10 also receives signals from mobile terminals. The signal transmitted by the mobile terminal is received by the antenna. The radio circuit unit (RF) 91 performs frequency conversion of a signal received by the antenna and converts it to a baseband signal. The signal converted into the baseband signal by the radio circuit unit (RF) 91 is subjected to signal processing in the baseband unit (BB) 92, and the decoding process is completed. The success or failure of decoding is notified to the mobile terminal by ACK or NACK information, and processing such as HARQ is performed as necessary. The ACK or NACK information generated here is generated by the baseband unit (BB) 92 and transmitted from the antenna through the radio circuit unit (RF) 91.

  The information that has been decoded is transmitted to the base station. A baseband signal is generated in the baseband unit (BB) 92 at an appropriate timing and an appropriate frequency according to an instruction from the CPU 93. The generated signal is sent to a radio circuit unit (RF) 91, converted into a radio frequency, and transmitted from an antenna.

1 relay station 1-1 relay station 1-2 relay station 1-3 relay station 1-4 relay station 2 mobile terminal 3 base station 3-1 base station 3-2 base station 4 base station controller 5 center station 6 1 Shield 6-2 Shield 7-1 Area with poor signal quality 7-2 Area with poor signal quality 8 Vending means 9 Communication means 10 Relay station integrated in combination with vending means

Claims (3)

Multiple relay stations that can operate in two modes: a relay function that transmits a signal received from the base station to the mobile terminal and a signal received from the mobile terminal to the base station, and a transmission / reception function as the mobile terminal A connected center station,
The center station
Position information of the relay station included in a report transmitted from the plurality of relay stations, quality information of a signal received from a base station to which the relay station is connected, and movement connected to the base station or the relay station Position information included in the report transmitted from the mobile terminal, quality information of the received signal from the base station to which the mobile terminal is connected, a threshold of quality information for determining the dead point, Storage means for storing a distance threshold;
Having control means,
The control means includes
Identify the dead spot based on the report location information whose quality information is lower than the quality information threshold,
With reference to the position information and quality information of the plurality of relay stations stored in the storage means, the relay station whose distance from the dead point is equal to or less than a predetermined threshold of the distance among the plurality of relay stations In addition, the relay station having the best reception quality is selected from the selected relay stations, and when the relay station is operating as a mobile terminal, an instruction signal for instructing to operate as a relay station The center station characterized by transmitting. 2. The center according to claim 1 , wherein when the selected relay station is already operating as a relay station, it is determined that an abnormality has occurred in the selected relay station, and an alarm is generated. Bureau. A plurality of relay stations operable in two modes: a relay function for transmitting a signal received from a base station to a mobile terminal and a signal received from the mobile terminal to the base station, and a transmission / reception function as the mobile terminal When,
A mobile radio communication system having a center station to which the plurality of relay stations are connected,
The center station
Position information of the relay station included in a report transmitted from the plurality of relay stations, quality information of a signal received from a base station to which the relay station is connected, and movement connected to the base station or the relay station Position information included in the report transmitted from the mobile terminal, quality information of the received signal from the base station to which the mobile terminal is connected, a threshold of quality information for determining the dead point, Memorize the distance threshold,
Based on the stored information, a dead point is identified based on the position information of a report whose quality information is lower than the threshold value of the quality information, and the plurality of relays are referred to by referring to the position information and quality information of the plurality of relay stations. A relay station having a distance from the dead point that is equal to or less than a predetermined threshold is selected from the stations, and a relay station having the best reception quality is selected from the selected relay stations, and the relay station is selected. When operating as a mobile terminal, a mobile radio communication system characterized by transmitting an instruction signal instructing to operate as a relay station.

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