JP2013074399A - Relay device and communication control method - Google Patents

Abstract

A relay apparatus and a communication control method capable of efficiently suppressing the influence of mutual interference are provided.
A relay apparatus 101 according to the present invention is a relay apparatus 101 that relays a radio signal transmitted and received between a base station and a mobile station, and the base station and the radio signal are transmitted via a base station antenna 115. At least one of the base station side antenna 115, the mobile station side antenna 115, the mobile station side antenna 122 that transmits and receives radio signals to and from the mobile station via the mobile station side antenna 122, the base station side antenna 115, and the mobile station side antenna 122. The antenna directivity adjustment unit 125 that changes the directivity and the mutual interference degree of the relay apparatus 101 are calculated, and the antenna directivity adjustment unit 125 is changed so as to change the antenna directivity according to the calculated mutual interference degree. And a control unit 121 for controlling.
[Selection] Figure 2

Description

  The present invention relates to a relay device and a communication control method.

  In order for a mobile station to communicate with a base station, the mobile station needs to be located in a range (service area) where radio waves from the base station can reach. However, in urban areas where mountainous areas and high-rise buildings are lined up, there are areas where radio waves are difficult to reach due to many obstacles. In addition, there are many areas (for example, the inside of a building and the basement) where radio waves do not reach from base stations installed outdoors. In particular, in a high-speed wireless communication method such as WiMAX (Worldwide Interoperability for Microwave Access) (registered trademark) standardized based on the IEEE standard 802.16e, radio waves in a high frequency band of 2.5 GHz or more are used. Such radio waves are highly straight and have a weak property of going around obstacles. For this reason, WiMAX and the like are strongly affected by obstacles. In order to cover such a region where radio waves do not reach, a relay device (repeater) that relays radio signals between the base station and the mobile station is required.

  This relay device has the advantage that the service area can be expanded, but has the disadvantage that radio waves emitted by the relay device cause interference with other radio waves. One of the interferences caused by relay devices is between a donor node (MS (Mobile Station) unit) that communicates with a base station and a service node (BS (Base Station) unit) that communicates with a mobile station. Mutual interference (wraparound interference or self-interference) can be mentioned. For example, when the reception period of the donor node and the transmission period of the service node overlap, the transmission wave from the base station interferes with the transmission wave of the service node, and the donor node transmits the transmission wave from the base station with degraded quality. Will be received. Similarly, mutual interference also occurs when the transmission period of the donor node and the reception period of the service node overlap.

  When the mutual interference occurs, the reception quality at the donor node and the service node of the relay apparatus deteriorates. However, a method for obtaining the reception quality by threshold processing is known (for example, see Patent Document 1). In Patent Document 1, a UWB (Ultra Wide Band) relay apparatus measures a bit error rate of a received signal (received signal) and compares the bit error rate with a predetermined threshold. When the bit error rate exceeds the threshold, the UWB relay device determines that the reception quality is not good. If the bit error rate is equal to or less than the threshold, it is determined that the reception quality is good.

JP 2004-336440 A

  Information on whether or not the reception quality is good is also taken into consideration when determining the installation position of the relay apparatus. In particular, when determining the installation location of the relay apparatus that can arrange the donor node and the service node independently, it is important to specify the arrangement position where the influence of mutual interference is reduced.

  It is assumed that the position of the relay apparatus where the influence of mutual interference is reduced is determined as follows. First, when the service node is stopped, that is, when the donor node is not emitting radio waves, the donor node receives a signal from the base station, and receives the CINR (Carrier to Interference and Noise Ratio) of the signal. Ratio). Subsequently, when the service node transmits an interference measurement signal to the mobile station, the donor node calculates the CINR of the signal from the base station. Then, the relay apparatus subtracts CINR when the service node transmits a signal from CINR when the service node is stopped to obtain a difference. The larger the difference, the smaller the CINR value at the time of signal transmission by the service node, which means that the influence of mutual interference is stronger. If the difference is less than the predetermined threshold, it can be determined that there is no mutual interference. If the difference is equal to or greater than a predetermined threshold, it can be determined that there is mutual interference. By the threshold processing of the difference, it is possible to specify the positional relationship between the donor node and the service node that are determined to have no mutual interference.

  However, in this method, it is necessary to move the donor node or the service node many times before specifying the position where it is determined that there is no mutual interference, which is very laborious and time consuming. In addition, if the communication environment around the relay device has changed after the relay device has been installed, the donor node or service node must be moved again to identify the position where it is determined that there is no mutual interference. Don't be.

  Accordingly, an object of the present invention made in view of the above problems is to provide a relay apparatus and a communication control method that can efficiently suppress the influence of mutual interference.

In order to solve the above-mentioned problems, the invention according to the first aspect is
A relay device that relays radio signals transmitted and received between a base station and a mobile station,
A base station side communication unit that transmits and receives radio signals to and from the base station via a base station side antenna;
A mobile station side communication unit that transmits and receives radio signals to and from the mobile station via a mobile station side antenna;
An antenna directivity adjustment unit that changes the directivity of at least one of the base station side antenna or the mobile station side antenna;
Calculate the degree of mutual interference of the relay device, and control the antenna directivity adjustment unit so as to change the directivity of at least one of the base station side antenna or the mobile station side antenna according to the calculated degree of mutual interference And a control unit.

  The invention according to the second aspect is the relay apparatus according to the first aspect, wherein the control unit does not receive a connection request signal from the mobile station when the mobile station side communication unit is in communication service. In addition, the degree of mutual interference is calculated.

The invention according to the third aspect is the relay device according to the first aspect or the second aspect.
The relay device further includes a display unit,
The said control part controls a display part so that a display mode may be changed according to the said mutual interference degree.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program, which are substantially equivalent thereto, and the scope of the present invention. It should be understood that these are also included.

For example, a communication control method that realizes the first aspect of the present invention as a method includes:
In a communication control method in a relay apparatus that relays radio signals transmitted and received between a base station and a mobile station, the relay apparatus includes:
Transmitting and receiving radio signals to and from the base station via a base station side antenna;
Transmitting and receiving radio signals to and from the mobile station via a mobile station antenna;
Calculating a mutual interference degree of the relay device, and changing a directivity of at least one of the base station side antenna or the mobile station side antenna according to the calculated mutual interference degree.

  According to the relay apparatus and the communication control method according to the present invention configured as described above, the antenna directivity adjustment unit changes the antenna directivity according to the degree of mutual interference. The influence of mutual interference can be suppressed without being moved manually.

FIG. 1 is a schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. FIG. 2 is a functional block diagram illustrating a schematic configuration of the relay device according to the embodiment of the present invention. FIG. 3 is a flowchart showing processing of the relay device according to the embodiment of the present invention.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. The radio communication system 11 includes a base station BS (Base Station), a mobile station MS (Mobile Station), and a relay device 101. When the communication method of the wireless communication system 11 is WiMAX, for example, a time division duplex (TDD) method is adopted for the wireless communication system 11. The relay apparatus 101 relays a radio signal (data) transmitted and received between the base station BS and the mobile station MS in a wireless communication method such as WiMAX. The mobile station MS can transmit and receive radio signals to and from the base station BS via the relay device 101 even if the mobile station MS is located outside the cell (communication area) of the base station BS.

  FIG. 2 is a functional block diagram illustrating a schematic configuration of the relay device according to the embodiment of the present invention.

  The relay apparatus 101 includes a donor node (MS (Mobile Station) unit) 111 that communicates with a base station BS and a service node (BS (Base Station) unit) 113 that communicates with a mobile station MS. The relay device 101 is an integral type, a separation type, or a vehicle type. The integrated relay apparatus 101 includes a donor node 111 and a service node 113 in one housing. In the separation-type or vehicle-type relay device 101, the donor node 111 and the service node 113 can be arranged independently of each other. The separate or vehicle-type donor node 111 and the service node 113 are connected by a signal cable such as a LAN (Local Area Network) cable.

  First, functional blocks of the donor node 111 will be described. The donor node 111 includes a base station side communication unit 117, a storage unit 119, and a control unit 121. The base station side communication unit 117 and the storage unit 119 are connected to the control unit 121.

  The base station side communication unit 117 transmits and receives radio signals to and from the base station BS via the base station side antenna 115. The base station side communication unit 117 generates a baseband signal by performing amplification and down-conversion with low noise on the received radio signal, and sends the baseband signal to the control unit 121. Also, the base station side communication unit 117 generates a radio signal by up-converting and amplifying the baseband signal, and transmits the radio signal to the base station BS via the base station side antenna 115. .

  The storage unit 119 stores various information such as a mutual interference threshold related to the degree of mutual interference of the relay apparatus 101, and also functions as a work memory.

  The degree of mutual interference of the relay apparatus 101 is the effect that the transmission wave of the service node 113 has on the radio signal from the base station BS received by the donor node 111, or the transmission wave of the donor node 111 is received by the service node 113. This is an influence on a radio signal from the mobile station MS. The degree of mutual interference is, for example, a value related to CINR (Carrier to Interference and Noise Ratio) and SINR (Signal to Interference and Noise Ratio). CINR and SINR mean that the larger the value, the smaller the influence of interference and noise. Hereinafter, in this embodiment, it is assumed that the degree of mutual interference is CINR. Note that it is conceivable that the service node 113 serving as the base station BS transmits a radio signal with higher power than the donor node 111. Therefore, the degree of mutual interference regarding the transmission wave (transmission signal) of the service node 113 is greater than the degree of mutual interference regarding the transmission wave of the donor node 111. Therefore, in the present embodiment, the degree of mutual interference is assumed to be the effect that the transmission wave of the service node 113 has on the radio signal from the base station BS received by the donor node 111.

  The mutual interference threshold is an index indicating whether or not a radio signal affected by mutual interference has good communication quality for the donor node 111, and is an item that can be arbitrarily set. Good communication quality for the donor node 111 is, for example, quality that the donor node 111 can demodulate. Hereinafter, in the present embodiment, it is assumed that the mutual interference threshold is an index indicating whether or not the donor node 111 has a demodulatable quality. When the degree of mutual interference is less than the mutual interference threshold, the donor node 111 can demodulate the radio signal received from the base station BS. If the degree of mutual interference is equal to or greater than the mutual interference threshold, there is a high possibility that the donor node 111 cannot demodulate the radio signal from the base station BS.

  In the present embodiment, only the donor node 111 has the storage unit 119, but the present invention is not limited to this configuration. For example, only the service node 113 may have a storage unit, and the storage unit may store various information of the donor node 111 and the service node 113. Moreover, both the donor node 111 and the service node 113 have a storage unit, and each storage unit can store information on each unit associated with the storage unit.

  The control unit 121 controls and manages the entire donor node 111 and service node 113 as well as the functional blocks of the donor node 111 and service node 113. Here, the control unit 121 is configured as software executed on any suitable processor such as a CPU (Central Processing Unit), or a dedicated processor specialized for each process (for example, DSP (Digital Signal Processor)). Can also be configured. In the present embodiment, only the donor node 111 has the control unit 121, but the present invention is not limited to this configuration. For example, only the service node 113 has a control unit, and the control unit can control and manage the donor node 111 and the service node 113 as a whole. Further, both the donor node 111 and the service node 113 have a control unit, and each control unit can control and manage each unit related to the control unit. The processing performed by the control unit 121 will be described in detail with reference to FIG.

  Next, functional blocks of the service node 113 will be described. The service node 113 includes a mobile station side communication unit 123, an antenna directivity adjustment unit 125, and a display unit 127. The mobile station side communication unit 123, the antenna directivity adjustment unit 125, and the display unit 127 are connected to the control unit 121.

  The mobile station side communication unit 123 transmits and receives radio signals to and from the mobile station MS via the mobile station side antenna 122. The mobile station side communication unit 123 generates a baseband signal by performing amplification and down-conversion with low noise on the received radio signal, and sends the baseband signal to the control unit 121. Also, the mobile station side communication unit 123 generates a radio signal by performing up-conversion and amplification on the baseband signal, and transmits the radio signal to the mobile station MS via the mobile station side antenna 122. .

  The antenna directivity adjustment unit 125 changes the directivity of the mobile station side antenna 122. Changing the directivity means, for example, shifting the main axis of directivity by 10 degrees. The directivity is changed according to the degree of mutual interference. For example, the directivity is changed when the degree of mutual interference exceeds a threshold value. In addition, the amount of change in directivity can be increased as the degree of mutual interference increases. The mode of changing the directivity is a matter that can be arbitrarily set according to the degree of mutual interference.

  When the mobile station side antenna 122 is physically moved, the antenna directivity adjusting unit 125 can be configured by an antenna rotator, for example. Further, when the mobile station side antenna 122 is realized as an adaptive array antenna, the antenna directivity adjustment unit 125 may be configured as software that adjusts the phase of the transmission radio wave of the mobile station side antenna 122. In this case, the antenna directivity adjusting unit 125 can be configured as a part of the control unit 121. The present invention is not limited to the antenna directivity adjustment unit 125 changing the directivity of the mobile station side antenna 122. For example, the antenna directivity adjustment unit 125 can also change the directivity of the base station side antenna 115. In this case, the donor node 111 may include the antenna directivity adjustment unit 125 instead of the service node 113. Furthermore, the antenna directivity adjustment unit 125 can also change the directivities of both the base station side antenna 115 and the mobile station side antenna 122.

  The display unit 127 visually represents the degree of mutual interference to the user, and is configured using, for example, a liquid crystal display panel, an organic EL display panel, an LED (Light Emitting Diode). For example, when the display unit 127 is composed of a liquid crystal display panel or an organic EL display panel, it indicates by characters that the degree of mutual interference is less than the mutual interference threshold or that the degree of mutual interference is greater than or equal to the mutual interference threshold. be able to. In addition, when the display unit 127 is composed of LEDs, the display unit 127 lights a color corresponding to the mutual interference level less than the mutual interference threshold or a corresponding color when the mutual interference level is equal to or greater than the mutual interference threshold. Can do. Furthermore, the display unit 127 can not only determine whether or not the mutual interference level is less than the mutual interference threshold depending on the character content and the type of color, but can also express the mutual interference level in a finer stepwise manner. Note that the donor node 111 may include the display unit 127 instead of the service node 113.

  Next, a method in which the relay apparatus 101 suppresses mutual interference between the base station side communication unit 117 and the mobile station side communication unit 123 will be described with reference to FIG. FIG. 3 is a flowchart showing processing of the relay device according to the embodiment of the present invention.

  First, the control unit 121 of the relay apparatus 101 causes the mobile station side communication unit 123 to transmit an interference measurement signal (step S101). The base station side communication unit 117 receives a radio signal from the base station BS during transmission of the interference measurement signal by the mobile station side communication unit 123. That is, the radio signal is affected by mutual interference with the interference measurement signal. Note that the interference measurement signal is not limited to a signal transmitted only for the relay apparatus 101 to measure the mutual interference, and may be a signal to be transmitted to the mobile station MS, for example. .

  The control unit 121 calculates the CINR of the radio signal affected by the mutual interference (Step S102). Then, the control unit 121 stores the calculated CINR in the storage unit 119.

  Subsequently, the control unit 121 causes the mobile station side communication unit 123 to stop transmitting the interference measurement signal (step S103). The base station side communication unit 117 receives a radio signal from the base station BS while the mobile station side communication unit 123 stops transmitting the interference measurement signal. That is, the radio signal is not affected by mutual interference with the interference measurement signal.

  The control unit 121 calculates the CINR of the radio signal that is not affected by the mutual interference (step S104). And the control part 121 takes out CINR when the signal for interference measurement is transmitted from the memory | storage part 119, and calculates a mutual interference degree (step S105). The degree of mutual interference is obtained from the difference between the CINR when the interference measurement signal is transmitted and the CINR when the interference measurement signal transmission is stopped. When the radio signal is affected by mutual interference, the value of CINR decreases. Therefore, the degree of mutual interference is (degree of mutual interference) = (CINR at the time of transmission of interference measurement signal) − (transmission stop of interference measurement signal) (CINR at the time).

  The control unit 121 compares the degree of mutual interference with the mutual interference threshold stored in the storage unit 119 (step S106). When the degree of mutual interference is less than the threshold (Yes in step S106), the control unit 121 determines that the radio signal can be correctly demodulated even if the radio signal from the base station BS is affected by the mutual interference. Therefore, the control unit 121 maintains the directivity of the mobile station side antenna 122 without changing it.

  At this time, the control unit 121 can change the display mode of the display unit 127 according to the degree of mutual interference. For example, the control unit 121 can control the display unit 127 to display characters corresponding to the fact that the degree of mutual interference is less than a threshold, or to light a color corresponding to that effect.

  When the degree of mutual interference is greater than or equal to the threshold (No in step S106), there is a high possibility that the control unit 121 cannot correctly demodulate the radio signal affected by the mutual interference. Therefore, in order to identify the directivity of the mobile station side antenna 122 in which the influence of mutual interference is suppressed, the control unit 121 controls the antenna directivity adjustment unit 125 to change the directivity of the mobile station side antenna 122. (Step S107).

  At this time, the control unit 121 can control the display unit 127 to display characters corresponding to the fact that the degree of mutual interference is equal to or greater than a threshold value, or to light a color corresponding to that effect.

  Then, steps S101 to S107 are repeated until the mutual interference level is less than the threshold value.

  It should be noted that the present invention is not limited to the relay apparatus 101 performing steps S101 to S107 before the mobile station side communication unit 123 starts communication service with the mobile station MS. It is. For example, the relay apparatus 101 has not received a connection request signal from the mobile station MS after the mobile station side communication unit 123 starts communication service with the mobile station MS, that is, when the mobile station side communication unit 123 is in communication service. In such a case, the processes in steps S101 to S107 can be performed. When the connection request signal is not received from the mobile station MS, there is no signal to be sent to the mobile station MS, and therefore the interference measurement signal can be transmitted without interfering with the existing communication.

  As described above, in the present embodiment, the control unit 121 of the relay apparatus 101 calculates the degree of mutual interference caused by the interference measurement signal of the service node 113 and the signal from the base station BS, and according to the calculated degree of mutual interference. The antenna directivity adjustment unit 125 is controlled so as to change the directivity of the mobile station antenna 122. That is, when the degree of mutual interference is equal to or greater than the mutual interference threshold that is an index indicating whether or not the communication quality is good, the antenna directivity adjustment unit 125 changes the directivity of the mobile station antenna 122. Since the antenna directivity adjustment unit 125 continues to change the directivity of the mobile station antenna 122 until the degree of mutual interference becomes less than the mutual interference threshold, it is not necessary to move the service node 113 manually, and the mutual interference can be efficiently performed. Can be suppressed.

  In the present embodiment, the control unit 121 can calculate the degree of mutual interference when the mobile station side communication unit 123 has not received a connection request from the mobile station MS at the time of service. That is, even when the mobile station side communication unit 123 is in service, the control unit 121 can cause the antenna directivity adjustment unit 125 to change the directivity of the mobile station antenna 122 according to the degree of mutual interference. Therefore, even when a large amount of mutual interference occurs due to a change in the communication environment around the relay apparatus 101, the mutual interference can be reduced by changing the directivity of the mobile station antenna 122.

  Moreover, in this embodiment, the control part 121 can control the display part 127 so that a display mode may be changed according to a mutual interference degree. Thereby, the control part 121 can make a user recognize the degree of the mutual interference currently occurring.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

  For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible.

  In the above description of the embodiment of the present invention, for example, the meaning of the technical idea of the expression such as the mutual interference threshold “greater than” or the mutual interference threshold “less than” is not necessarily a strict meaning. Depending on the case, the meaning when the reference value is included or not included is included. For example, the mutual interference threshold “above” may imply not only when the mutual interference level reaches the mutual interference threshold but also when the mutual interference threshold is exceeded. For example, the mutual interference threshold “less than” may imply not only when the mutual interference level is below the mutual interference threshold but also when the mutual interference threshold is reached, that is, when the mutual interference threshold is lower than the mutual interference threshold. To do.

DESCRIPTION OF SYMBOLS 11 Wireless communication system 101 Relay apparatus 111 Donor node 113 Service node 115 Base station side antenna 117 Base station side communication part 119 Memory | storage part 121 Control part 122 Mobile station side antenna 123 Mobile station side communication part 125 Antenna directivity adjustment part 127 Display part BS base station MS mobile station

Claims (4)

A relay device that relays radio signals transmitted and received between a base station and a mobile station,
A base station side communication unit that transmits and receives radio signals to and from the base station via a base station side antenna;
A mobile station side communication unit that transmits and receives radio signals to and from the mobile station via a mobile station side antenna;
An antenna directivity adjustment unit that changes the directivity of at least one of the base station side antenna or the mobile station side antenna;
A control unit that calculates the degree of mutual interference of the relay device and controls the antenna directivity adjustment unit to change at least one of the base station side antenna or the mobile station side antenna according to the calculated degree of mutual interference A relay device comprising: The relay device according to claim 1, wherein the control unit includes:
A relay apparatus, wherein the mobile station side communication unit calculates the degree of mutual interference when a connection request signal from a mobile station is not received during a communication service. In the relay device according to claim 1 or 2,
The relay device further includes a display unit,
The said control part controls a display part so that a display mode may be changed according to the said mutual interference degree, The relay apparatus characterized by the above-mentioned. In a communication control method in a relay apparatus that relays radio signals transmitted and received between a base station and a mobile station, the relay apparatus includes:
Transmitting and receiving radio signals to and from the base station via a base station side antenna;
Transmitting and receiving radio signals to and from the mobile station via a mobile station antenna;
Calculating the degree of mutual interference of the relay device, and changing the directivity of at least one of the base station side antenna or the mobile station side antenna according to the calculated degree of mutual interference.

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