JP2010016773A - Communication apparatus, and wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a communication apparatus to which a signal transmitted from a base station and containing transmission frequency information is relayed by another communication apparatus including a frequency conversion function and which is normally operable even if a signal of a frequency different from the frequency in transmission from the base station is received. <P>SOLUTION: The invention relates to a communication apparatus operating as a mobile station in a wireless communication system including a base station which transmits a signal containing transmission frequency information, the mobile station communicating with the base station and a wireless device relaying a signal exchanged between the base station and the mobile station. The communication apparatus includes: a control packet transmitting/receiving unit 33 for acquiring transmission frequency information contained in a reception signal; and a reception frequency determining unit 32 for determining an operation to be executed subsequently on the basis of the acquired transmission frequency information and reception frequency information of the reception signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication device that operates as a mobile station in a wireless communication system including a wireless device (relay device) having a function of transferring a received signal while converting the frequency.

  In the IEEE 802.16 wireless communication system, the base station (BS: Base Station) radio channel information is included by a DCD (DL Channel Descriptor) message and a UCD (UL Channel Descriptor) message, which are C-Plane (Control Plane) messages. The broadcast information is broadcast to each mobile station (MS). This broadcast information includes information such as BSID, center frequency (radio channel information), frame configuration, control information, and the like. The mobile station performs communication with the base station using various information acquired from the received broadcast information (see Non-Patent Document 1 below).

  Also, in a radio communication system, the frequency of a signal (radio signal) transmitted from a base station is converted by a radio device on the transmission path, and a radio signal having a frequency different from the frequency transmitted from the base station moves. There is a system that reaches (receives) the station.

  For example, as a technology for eliminating the dead zone where the base station cannot see the mobile station, such as indoors or inside a tunnel, a device located between the mobile station and the base station uses the same or different received signal (radio wave). There is a technology for relaying at a frequency. More specifically, as a device that relays radio waves, a radio device (relay device) that controls lower links and relays received packets at the same frequency or different frequencies, and received radio waves without controlling lower links. Exists in the same frequency or different frequencies. The former relay device is being standardized as an IEEE 802.16j Multihop Relay System standard especially for those using WiMAX as a wireless communication system. On the other hand, the latter, which converts the frequency in the radio layer, is not defined in the IEEE 802.16 standard, and there is no standardized standard.

IEEE P802.16 Rev2 / D5 (June 2008)

  As described above, the IEEE 802.16 standard does not define a repeater that converts a frequency in the radio layer. For this reason, in the wireless communication system of the IEEE 802.16 standard, the base station and the mobile station cannot communicate via the repeater, and in order to eliminate the dead zone where the mobile station cannot see the radio wave, the lower link There is a problem that a repeater that does not need to be controlled cannot be used.

  For example, as an example of a radio communication system in which a frequency is converted, a system in which a repeater that converts a frequency exists between a base station and a mobile station and relays radio waves is assumed. In this system, the base station notifies the mobile station of broadcast information including information on the center frequency of the radio wave transmitted by itself. On the other hand, the repeater converts the frequency of the radio wave received from the base station, and transmits (transfers) at a frequency different from the frequency at the time of reception. As a result, in the mobile station, the frequency indicated by the center frequency information included in the broadcast information is different from the radio frequency of the actually received radio wave, resulting in a contradiction. And since the solution to such a problem is not defined in IEEE 802.16, the operation of the mobile station becomes unpredictable in the wireless communication system of the IEEE 802.16 standard.

  The present invention has been made in view of the above, and a signal transmitted from a base station is relayed by a repeater having a frequency conversion function, and a signal having a frequency different from the frequency at the time of transmission from the base station is received. It is an object of the present invention to obtain a communication device and a wireless communication system that operate as a mobile station that can operate normally even in such a case.

  In order to solve the above-described problems and achieve the object, the present invention provides a base station that transmits a signal including transmission frequency information, a mobile station that communicates with the base station, and between the base station and the mobile station. In a wireless communication system including a wireless device that relays a signal transmitted / received in the communication device, the communication device operates as the mobile station, and acquires transmission frequency information included in a received signal from the base station or the wireless device Transmission frequency information acquisition means; and execution operation determination means for determining an operation to be executed later based on the acquired transmission frequency information and reception frequency information of the received signal.

  According to the present invention, the communication device operating as a mobile station determines an operation to be performed thereafter based on the transmission frequency information included in the received signal and the received frequency information indicating the actual frequency of the received signal. Therefore, even if the frequency of the signal transmitted from the base station is converted on the transmission line and a signal with a frequency different from the original frequency (frequency when the base station transmits) is received, it operates normally. There is an effect that can be done.

  Embodiments of a communication apparatus and a wireless communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a wireless communication system including a communication device according to the present invention. This wireless communication system includes a base station (BS) 1, a wireless device (Repeator) 2, and a mobile station (MS) 3, and is, for example, a wireless communication system of the IEEE 802.16 standard.

  The base station 1 transmits a radio signal including transmission frequency information in a cell (Cell) managed by the base station 1. This transmission frequency information is, for example, channel information indicating the center frequency of the transmission signal (hereinafter simply referred to as “frequency”), and information broadcast from the base station 1 to the subordinate mobile station 3 (broadcast information) )include. The broadcast information is broadcast in the cell by a control message such as a DCD message or a UCD message.

The wireless device 2 is located in a cell managed by the base station 1 and operates as a repeater that relays a received signal (received radio wave) from the base station 1. Also, when the mobile station 3 receives a signal transmitted to the base station 1, the received signal is relayed. The wireless device 2 has a function of transmitting (transferring) a signal at a frequency different from the frequency at the time of reception. In the example shown in FIG. 1, a signal having a frequency f ₁ is received from the base station 1 and transferred at the frequency f ₂ .

  The mobile station 3 communicates with the base station 1. However, if direct communication with the base station 1 is impossible, communication is performed via the wireless device 2. Therefore, the mobile station 3 compares the transmission frequency (frequency indicated by the transmission frequency information) notified from the base station 1 with the actual reception frequency (frequency of the reception signal), and if these do not match, the mobile station 3 is notified. Ignore the transmitted frequency and execute the operation according to the actual received frequency.

  That is, in the wireless communication system of the present embodiment, the mobile station 3 compares the frequency indicated by the transmission frequency information notified from the base station 1 with the frequency of the actually received signal, and when these frequencies are different, It is determined that the frequency has been converted by the device 2. The mobile station 3 ignores the transmission frequency information notified from the base station 1 and performs communication according to the frequency of the actual received signal.

  Further, in the wireless communication system of the present embodiment, the example in which the transmission frequency information is different from the actual frequency of the received signal has been shown. However, unexpected information elements are also included in other information elements included in the broadcast information. In the case of an error, the corresponding information element is ignored and skipped.

  Although FIG. 1 shows an example in which there is one radio apparatus 2 present in the cell managed by the base station 1, there may be a plurality of radio apparatuses. Similarly, there may be a plurality of mobile stations 3 that can communicate with the base station 1 directly or via the wireless device 2. In addition, the wireless device 2 may transfer the received signal using the same frequency as the frequency at which the signal is received. That is, in the relay operation by the wireless device 2, the frequency conversion process is not essential.

  FIG. 2 is a diagram showing an internal configuration example of each device (base station, wireless device, mobile station) included in the wireless communication system of the present embodiment shown in FIG.

  As illustrated, the base station 1 performs control between the mobile station 3 and the information packet transmission / reception unit 11 that forms a U-Plane (User Plane) for transmitting / receiving user data to / from the mobile station 3. A control packet transmitting / receiving unit 12 constituting a C-Plane for transmitting / receiving information, a baseband signal processing unit 13 for executing predetermined baseband signal processing when transmitting / receiving a signal to / from the mobile station 3, And an RF processing unit 14 that executes predetermined radio signal processing (high-frequency signal processing) when transmitting and receiving signals to and from the mobile station 3.

  The wireless device 2 includes a baseband signal processing unit 21 that performs predetermined baseband signal processing when relaying a signal transmitted and received between the base station 1 and the mobile station 3, and a predetermined wireless signal when relaying the signal. RF processing units 22 and 23 for performing signal processing.

  The mobile station 3 transmits / receives control information to / from the base station 1 and an information packet transmitting / receiving unit 31 constituting a U-Plane for transmitting / receiving user data to / from the base station 1. When a signal is transmitted / received between the reception frequency determination unit 32 (corresponding to the execution operation determination unit) and the control packet transmission / reception unit 33 (corresponding to the transmission frequency information acquisition unit) constituting the Plane and the base station 1, a predetermined base A baseband signal processing unit 34 that performs band signal processing, and an RF processing unit 35 that performs predetermined radio signal processing when transmitting and receiving signals to and from the base station 1 are provided.

  Next, the operation of each device in the wireless communication system having the above configuration will be described in detail. Here, as a characteristic operation of the present embodiment, “when the base station 1 and the mobile station 3 start communication, the base station 1 transmits a control signal (control frequency information) including information on the transmission signal (transmission frequency information). The operation when the mobile station 3 receives the signal via the wireless device 2 ”will be mainly described.

In the base station 1, when starting communication with the mobile station 3, the control packet transmission / reception unit 12 generates a control packet including transmission frequency information. This control packet is broadcasted via the baseband signal processing unit 13 and the RF processing unit 14. The control packet includes a DCD message for broadcasting information on a DL (Down Link) radio channel in the cell and a UCD message for broadcasting information on a UL (Up Link) radio channel in the cell. The DCD message includes a BSID indicating the transmission source base station ₁ , information on the frequency f ₁ of the radio signal transmitted by the base station 1 (transmission frequency information), and other control information. The UCD message includes information on the frequency of a radio signal transmitted to the base station 1 (received by the base station 1) and other control information. The control packet is passed to the baseband signal processing unit 13 and subjected to predetermined berthband signal processing. Further, the RF processing unit 14 performs predetermined high-frequency processing and up-conversion, and the frequency is f ₁ . It is transmitted as a radio signal.

In the wireless device 2, the RF processing unit 22 receives the radio signal having the frequency f ₁ transmitted from the base station 1, and the RF processing unit 22 down-converts the received signal and converts it into a baseband signal. Next, the baseband signal processing unit 21 performs predetermined baseband signal processing on the received signal in the baseband, and passes the obtained baseband processed signal to the RF processing unit 23. RF processing unit 23 executes predetermined radio frequency processing on the received signal, the frequency is transmitted as a radio signal f _2.

In the mobile station 3, the radio signal of a frequency f ₂ which is relayed by the wireless device 2 and received by the RF processing unit 35, the RF processing unit 35 down-converts and executes predetermined radio frequency processing on the received signal, Convert to baseband signal. Next, the baseband signal processing unit 34 performs predetermined baseband signal processing on the received signal converted into the baseband signal. When the control packet is obtained by executing the baseband processing, the control packet is transferred to the control packet transmitting / receiving unit 33. On the other hand, when the packet obtained by executing the baseband signal processing is an information packet, it is passed to the information packet transmitting / receiving unit 31.

When receiving a control packet from the baseband signal processing unit 34, the control packet transmitting / receiving unit 33 acquires information on the frequency f ₁ of the radio signal transmitted from the base station 1 from the broadcast information included in the control packet. The frequency information is passed to the reception frequency determination unit 32. In addition, the RF processing unit 35 passes information on the radio frequency f ₂ of the received signal to the received frequency determining unit 32. The reception frequency determination unit 32 then performs an operation to be executed thereafter based on the frequency information (transmission frequency information) acquired from the control packet transmission / reception unit 33 and the frequency information (reception frequency information) acquired from the RF processing unit 35. decide. Processing performed by the reception frequency determination unit 32 is described below with reference to FIG. FIG. 3 is a sequence diagram illustrating an example of an execution operation determination process performed by the reception frequency determination unit 32.

As illustrated in FIG. 3, the reception frequency determination unit 32 receives information on the frequency f ₂ (reception frequency information) of the reception radio signal and information on the frequency f ₁ (transmission frequency information) included in the broadcast information (step) S1, S2), it is determined whether the two frequencies indicated by these pieces of information match (step S3). As a result of the determination, when the two frequencies match (step S3, Yes), the signal from the base station 1 is directly received or the signal relayed without being subjected to frequency conversion by the wireless device 2 is received. , And execution of normal communication (communication operation in the case of direct communication with the base station 1) is determined (step S6). On the other hand, when the two frequencies are different (step S3, No), it is determined that the frequency conversion is performed by the wireless device 2, and the frequency f ₁ (transmission frequency information) notified by the broadcast information is ignored. (step S4), and determines the communication execution by the frequency f ₂ of the received radio signal (step S5).

  Then, the mobile station 3 performs a communication operation according to the determination result by the reception frequency determination unit 32. When the radio device 2 performs frequency conversion, the signal transmitted from the mobile station 3 to the base station 1 (UL signal) is also converted in frequency by the radio device 2, but the base station 1 Since the frequency conversion opposite to the frequency conversion performed on the signal from the mobile station 3 to the mobile station 3 (DL signal) is performed, the base station 1 communicates directly with the mobile station 3 and via the wireless device 2. In any case of communication, a signal having the same frequency is received. That is, the base station 1 does not need to be aware of whether the communication partner is the mobile station 3 or the wireless device 2.

  As described above, in the radio communication system according to the present embodiment, the mobile station compares the frequency of the received signal with the frequency of the signal transmitted from the base station notified by the broadcast information, thereby determining whether or not frequency conversion has been performed. It was decided to detect and determine the frequency for communication. As a result, the operation at the time of mismatch between the frequency information (received frequency information) of the received signal and the frequency information (transmitted frequency information) included in the broadcast information is clarified, and the communication through the device that relays the signal by converting the frequency It can be realized. Further, by detecting the frequency conversion, it is possible to correctly operate functions based on the reception channel such as handover and transmission path measurement.

  In the present embodiment, an example of the operation of a mobile station in a wireless communication system in which a wireless device (repeater) performs baseband processing has been described. However, wireless communication including a wireless device having only a frequency conversion function of an RF processing unit. The control operation described above can also be applied to mobile stations in the system. The wireless device may have a function of performing packet processing after baseband processing.

  As described above, the technique shown in the present embodiment is effective when the frequency transmitted / received by the base station is different from the frequency transmitted / received by the mobile station, and limits the configuration of each device in the radio communication system. It is not a thing. The same applies to the embodiments described later.

Embodiment 2. FIG.
Next, the second embodiment will be described. In Embodiment 1, the operation in the case where the mobile station detects the presence / absence of frequency conversion based on broadcast information (transmission frequency information notified from the base station) and reception information (frequency information of the received signal) has been described. On the other hand, in the present embodiment, the base station notifies the mobile station of the frequency information of the signal after being relayed by the wireless device in addition to the frequency information of the transmission signal. Based on each frequency information notified from the station, an operation to be performed thereafter is determined. As described above, the base station explicitly indicates that the frequency is converted, whereby a radio communication system in which the frequency is converted can be realized. Further, by notifying the frequency conversion information, the mobile station can perform efficient handover and transmission path measurement. The configuration of the wireless communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

  FIG. 4 is a diagram illustrating an internal configuration example of each device (base station, wireless device, mobile station) included in the wireless communication system according to the second embodiment. The illustrated base station 1a according to the present embodiment has a configuration in which a relay frequency management unit 15 is added to the base station 1 according to the first embodiment (see FIG. 2). Since the other components are the same as those of the base station 1 shown in Embodiment 1, the same components are denoted by the same reference numerals, and description thereof is omitted. As shown in the figure, the relay frequency management unit 15 forms a C-Plane together with the control packet transmission / reception unit 12.

  The wireless device 2 of the present embodiment is the same as the wireless device 2 of the first embodiment (see FIG. 2). For this reason, the same reference numerals are used and description thereof is omitted. The mobile station 3a of the present embodiment is obtained by replacing the reception frequency determination unit 32 provided in the mobile station 3 (see FIG. 2) of the first embodiment with a reception frequency determination unit 32a, and other configurations. The elements are the same as those of the base station 1 shown in the first embodiment. Therefore, the same code | symbol is attached | subjected with respect to the same component, and the description is abbreviate | omitted.

  Hereinafter, the operation of each device in the wireless communication system according to the present embodiment will be described in detail with a focus on differences from the operation described in the first embodiment. As in the first embodiment, also in the present embodiment, when the base station 1 and the mobile station start communication, control including information on the channel used by the base station 1 for transmission to the mobile station 3 is performed. The operation when a signal (control packet) is transmitted and the mobile station 3 receives the signal via the wireless device 2 will be mainly described.

The relay frequency management unit 15 of the base station 1a manages the frequency (f ₂ ) of a radio signal (hereinafter referred to as “relay signal”) transmitted and received by the radio apparatus 2 to and from the mobile station 3a. Then, when starting communication with the mobile station 3a, the control packet transmitting / receiving unit 12 of the base station 1a transmits the frequency (f ₁ ) of the radio signal (hereinafter referred to as “direct signal”) transmitted and received by the base station 1a itself. A control packet (first control packet) including information and a control packet (second control packet) including information on the frequency (f ₂ ) of the relay signal managed by the relay frequency management unit 15 are generated. Each is transmitted to the mobile station 3a.

  Note that the relay frequency management unit 15 acquires, for example, the frequency information of the relay signal from the wireless device 2 in advance. Alternatively, the relay frequency management unit 15 instructs the wireless device 2 to use a frequency (relay signal frequency) to be used when the signal is relayed. In order to instruct the frequency of the relay signal, a control packet may be separately transmitted to the radio apparatus 2, or the radio apparatus 2 that has received the second control packet receives the frequency information of the relay signal included therein. May be used. Also, if a rule (frequency conversion rule) when the radio apparatus 2 performs frequency conversion is determined in advance, the relay frequency management unit 15 holds this rule, and this and the frequency of the signal directly. The frequency of the relay signal may be specified based on the above, and the specified result may be passed to the control packet transmitting / receiving unit 12. For example, if it is determined in advance that the wireless device 2 performs a relay operation according to a rule of performing relay (transmission) using a frequency higher than the frequency of the received signal by a certain interval, the relay frequency management unit 15 By using this rule, the frequency of the relay signal is specified from the frequency of the signal (direct signal) transmitted by itself (base station 1a).

When receiving the first and second control packets, the control packet transmission / reception unit 33 of the mobile station 3a includes the frequency (f ₁ ) information of the direct signal and the frequency of the relay signal included in each received control packet. The information of (f ₂ ) is extracted. Then, the extracted frequency information is passed to the reception frequency determination unit 32a. The reception frequency determination unit 32a is based on each frequency information (first / second transmission frequency information) received from the control packet transmission / reception unit 33 and frequency information (reception frequency information) acquired from the RF processing unit 35. Then, it is determined whether the received signal is directly received from the base station 1a or relayed by the wireless device 2 (identifies the communication partner). For example, when the frequency of the direct signal indicated by each frequency information notified from the base station 1a is different from the frequency of the relay signal, it is confirmed whether the frequency indicated by the reception frequency information matches the frequency of the direct signal or the relay signal. And specify the communication partner.

  And the mobile station 3a performs the communication operation according to the specific result by the receiving frequency determination part 32a. That is, when the base station 1a is the communication partner, communication is performed according to the frequency information of the direct signal, and when the wireless device 2 is the communication partner, communication is performed according to the frequency information of the relay signal.

  By performing such control, when the mobile station 3a is directly communicating with the base station 1a, the transmission path between the mobile station 3a and the wireless device 2 is determined according to the wireless frequency information of the wireless device 2 (frequency information of the relay signal). Measurement can be performed efficiently, and the wireless device 2 can be a candidate for a handover destination. Similarly, when communicating with the base station 1a via the radio apparatus 2, the transmission path measurement with the base station 1a is efficiently performed according to the radio frequency information (direct signal frequency information) of the base station 1a. In addition, the base station 1a can be set as a handover destination candidate.

  When frequency conversion is not performed in the radio apparatus 2, that is, when the frequency information of the direct signal notified from the base station 1a to the mobile station 3a and the frequency information of the relay signal indicate the same frequency, the mobile station 3a Performs normal communication without being aware of whether the communication partner is the base station 1a or the wireless device 2 (performs a communication operation similar to that in direct communication with the base station 1a).

  As described above, in the radio communication system according to the present embodiment, the base station involves frequency conversion in the radio apparatus in addition to the frequency information of the signal (direct signal) transmitted from the base station to the mobile station. The frequency information of the signal (relay signal) after relaying is explicitly notified. As a result, it is possible to realize a radio communication system in which the frequency is converted, and to perform efficient handover and transmission path measurement.

  In the present embodiment, the base station performs the second control including the first control packet including the frequency information of the direct signal transmitted by itself and the frequency information of the relay signal after frequency conversion by the wireless device. Although the configuration in the case of transmitting a packet to a mobile station has been shown, the base station may transmit by a single control packet including both frequency information of a direct signal and frequency information of a relay signal. . Any control packet may be used as long as it can notify the mobile station of the frequency information of the direct signal and the frequency information of the relay signal.

  As described above, the communication apparatus according to the present invention is useful for a mobile station that communicates with a base station that transmits a control signal (control packet) including transmission frequency information. In particular, the received signal is subjected to frequency conversion. This is suitable for a communication device that can operate normally even when a signal transferred by another communication device (repeater) having a function of transferring data is received.

It is a figure which shows the structural example of Embodiment 1 of the radio | wireless communications system containing the communication apparatus concerning this invention. 3 is a diagram illustrating an internal configuration example of each device (base station, wireless device, mobile station) included in the wireless communication system according to Embodiment 1. FIG. It is a sequence diagram which shows an example of the execution operation determination process by a receiving frequency determination part. 6 is a diagram illustrating an internal configuration example of each device (base station, wireless device, mobile station) included in a wireless communication system according to Embodiment 2. FIG.

Explanation of symbols

1, 1a Base station (BS)
2 Radio equipment (Repeater)
3, 3a Mobile station (MS)
11, 31 Information packet transmission / reception unit 12, 33 Control packet transmission / reception unit 13, 21, 34 Baseband signal processing unit 14, 22, 23, 35 RF processing unit 15 Relay frequency management unit 32, 32a Reception frequency determination unit

Claims (8)

In a wireless communication system including a base station that transmits a signal including transmission frequency information, a mobile station that communicates with the base station, and a wireless device that relays signals transmitted and received between the base station and the mobile station, A communication device that operates as the mobile station,
Transmission frequency information acquisition means for acquiring transmission frequency information included in a received signal from the base station or the wireless device;
Based on the acquired transmission frequency information and the received frequency information of the received signal, execution operation determining means for determining an operation to be performed thereafter,
A communication apparatus comprising:   The communication apparatus according to claim 1, wherein the execution operation determination unit determines whether to perform an operation according to the transmission frequency information based on the transmission frequency information and the reception frequency information.   The said execution operation | movement determination means determines execution of the operation | movement according to the said reception frequency information, when the frequency which the said transmission frequency information shows differs from the frequency which the said reception frequency information shows. Communication device.   The communication apparatus according to claim 1, 2 or 3, wherein the communication apparatus operates as a mobile station of a wireless communication system to which the IEEE 802.16 standard is applied. A wireless communication system comprising a base station, a mobile station that communicates with the base station, and a wireless device that relays signals transmitted and received between the base station and the mobile station,
The base station
A signal including first transmission frequency information which is frequency information of a signal transmitted by itself and second transmission frequency information which is frequency information of a signal transmitted from the wireless apparatus to the mobile station is addressed to the mobile station. To
The mobile station
The operation to be performed thereafter is determined based on the first and second transmission frequency information included in the reception signal from the base station or the radio apparatus and the reception frequency information of the reception signal. A wireless communication system.   The mobile station specifies whether the communication partner is the base station or the wireless device based on the first and second transmission frequency information and the reception frequency information, 6. The wireless communication system according to claim 5, wherein a communication operation according to the above is executed.   The radio communication system according to claim 5 or 6, wherein the mobile station uses the first and second transmission frequency information in a handover destination determination process when executing a handover.   The wireless communication system according to claim 5, 6 or 7, wherein the IEEE 802.16 standard is applied.

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