WO2013021526A1 - Relay station, base station, mobile communication system, backhaul link control method, and computer-readable medium - Google Patents

Abstract

A relay station (2) carries out a data relay between a base station (1) and a mobile station (3-2), using a backhaul link (BL1) which is connected to the base station (1) and an access link (AL2) which is connected to the mobile station (3-2). A mobile communication system is configured such that, while operating a relay station cell (20) using the access link (AL2) via the relay station (2), it is possible to switch the frequency which the backhaul ink (BL1) uses. The switch of the frequency which the backhaul link (BL1) uses includes at least one of a switch from an in-band frequency which is the same as the frequency which the access link (AL2) uses to an out-band frequency which differs from the frequency which the access link (AL2) uses, and a switch from the out-band frequency to the in-band frequency.

Description

Relay station, base station, mobile communication system, backhaul link control method, and computer-readable medium

The present invention relates to a mobile communication system including a base station and a relay station belonging to the base station, and more particularly to control of a frequency used for a backhaul link connecting the base station and the relay station.

In 3GPP (3rd Generation Partnership Project) LTE-Advanced (Long Term Evolution Advanced), introduction of a relay station (hereinafter referred to as RN: Relay node) is being studied (see Non-Patent Documents 1 and 2). RN is one of the technologies aimed at increasing the communication speed of a mobile station (hereinafter referred to as UE: User Equipment) at the cell edge and expanding the cell range of a base station (hereinafter referred to as eNB: Evolved Node B). The details of the RN architecture studied by 3GPP are described in Non-Patent Document 2.

In the following, an outline of a mobile communication system based on the RN architecture described in Non-Patent Document 2 will be described. FIG. 1 is a diagram illustrating an example of a network configuration when using RN, which is being studied in 3GPP. A base station (eNB) 91 belongs to a core network (hereinafter referred to as CN) 4 of a mobile communication carrier. The base station (eNB) 91 generates an eNB cell 10 and relays traffic between the mobile station (UE) 3-1 and the core network (CN) 4. Further, the relay station (RN) 92 belongs to the base station (eNB) 91 via the backhaul link (BL1 in the figure), and belongs to the core network (CN) 4 via the backhaul link (BL1). The relay station (RN) 2 can be connected to the management device 5 via the core network (CN) 4. The management device 5 is an OAM (Operation Administration and Maintenance) system and manages information set by a mobile communication carrier. The relay station (RN) 2 can acquire information from the management device 5. The mobile stations (UE) 3-1 and 3-2 belong to the base station (eNB) 91 or the relay station (RN) 92 through an access link (AL1 or AL2 in the figure). The relay station (RN) 92 generates the RN cell 20 and relays traffic between the mobile station (UE) 3-2 and the core network (CN) 4. The backhaul link and access link will be described later.

Fig. 2 is a sequence diagram showing an outline of the RN startup procedure described in Section 4.7.6 of Non-Patent Document 3. Note that the RN studied in 3GPP has a function of connecting to a network in the same procedure as a normal mobile station (UE). The RN startup procedure includes Phase 1 and Phase 2 described below. In phase 1, the relay station (RN) 92 is connected to the network (E-UTRAN / EPC) as a mobile station (UE) in the same procedure as a normal mobile station (UE) (steps S9002 and S9003). Then, the relay station (RN) 92 acquires initial setting parameters from the management device 5 (i.e. OAM system) (step S9004). The initial setting parameters include a list of eNB cells (donor cell list) that can be assigned as an RN using the backhaul link (BL1). After acquiring the initial setting parameters, the relay station (RN) 92 ends phase 1 by releasing the network connection as the UE (step S9005). Note that the base station (eNB) 91-1 to which the relay station (RN) 92 belongs in phase 1 may not have a function of receiving the attribution of the relay station (RN).

In phase 2, the relay station (RN) 92 selects one cell from at least one eNB cell (donor cell candidate) included in the donor cell list acquired from the management apparatus 5, and manages the selected cell. It belongs to the station (eNB) 91-2 as the relay station (RN) 2 (steps S9006 and S9007). Then, the relay station (RN) 92 acquires the setting information of the backhaul link (BL1) from the base station (eNB) 91 to which it belongs, and sets the backhaul link (BL) (step S9008). After completion of the phase 2 procedure, the relay station (RN) 92 starts operation of the relay station cell (RN cell) 20 (step S9009).

Also, as described in Non-Patent Document 4, there are three types of RNs that are being studied by 3GPP: Type 1, Type 1a, and Type 1b. The RN may support only one of these three types, may change the operation mode among a plurality of types, or may use a different operation mode between UEs. The type 1 RN uses the same frequency for the backhaul link and the access link, and time-divides the radio resource for the backhaul link and the radio resource for the access link. This is mainly intended to avoid interference from transmission of the access link at the RN to reception of the backhaul link. The RN operation mode using the same frequency for the bankhole link and the access link is called in-band (or inband) operation.

¡Type 1a RNs use different frequencies for the backhaul link and access link. Therefore, type 1a RNs do not require time sharing of radio resources like type 1 RNs, and perform independent communication between the backhaul link and the access link. The operation mode of RN that uses different frequencies for the backhaul link and the access link is called out-band (or outband, out-of-band) operation.

タ イ プ Type 1b RN, like Type 1 RN, performs in-band operation using the same frequency on the backhaul link and access link. However, type 1b RNs do not perform time division of radio resources. When this type is used, it is assumed that the interference to the reception of the backhaul link due to the transmission of the access link can be separated and suppressed.

RN transmits RN identification information including RN type to eNB in phase 2 of the startup procedure described above. And eNB determines the control method of a backhaul link based on RN type information contained in RN identification information. More specifically, the eNB determines whether to perform in-band operation or out-band operation and whether to time-divide radio resources of the backhaul link based on the RN type information.

In this specification, among eNBs, an eNB that accepts RN attribution is referred to as “Donor eNB (hereinafter DeNB)”. A mobile station (UE) directly belonging to a relay station (RN) is referred to as “RN-UE”. A mobile station (UE) directly belonging to a donor base station (DeNB) is referred to as “eNB-UE”. In the discussion on 3GPP, there is a demand to support multi-hop RN in the future. Multi-hop RN is a technology that enables cascade connection of relay stations (RN) to relay stations (RN) belonging to the eNB. In this specification, when describing multi-hop, the relay station (RN) belonging to the lower layer of the eNB with the radio interface is called `` upper RN '', and the relay station belonging to the lower layer of the upper RN with the radio interface ( RN) is referred to as “lower RN” for distinction. In this specification, a radio interface between the eNB and the RN and between the upper RN and the lower RN is referred to as a “backhaul link”. On the other hand, a radio interface between the eNB and the eNB-UE, and between the RN and the RN-UE is referred to as an “access link”.

The inventors of the present application conducted a detailed study on the method of switching the frequency used for the RN backhaul link. Whether or not to use the same frequency as the access link for the backhaul link, in other words, whether to use in-band operation or out-band operation, generally depends on the load on the RN cell (eg RN cell traffic volume). It is thought that it is decided based on. Furthermore, as described with reference to the sequence diagram of FIG. 2, whether to perform in-band operation or out-band operation is determined at the initial setup of the RN. Therefore, for example, it is considered that the backhaul link is set so as to be able to cope with the maximum value of the assumed load of the RN cell at the time of initial setup of the RN.

However, since the load on the RN cell changes depending on conditions such as the time zone, if the backhaul link is fixedly set based on the maximum value of the load on the RN cell, the frequency utilization efficiency may decrease. There is. For example, when the DeNB operates the access link (AL1) with the eNB-UE at the first frequency and operates the backhaul link (BL1) with the RN for out-band operation at the second frequency. Think. In the time zone when the number of UEs connected to the DeNB and the RN is small and the traffic volume to be handled by the DeNB and the RN is small, it is assumed that the utilization rates of the first and second frequencies are low. Therefore, if the first and second frequencies corresponding to the maximum load are always used in such a time zone in which the traffic volume is small, the frequency utilization efficiency decreases. It is not preferable to always use the first and second frequencies corresponding to the maximum load from the viewpoint of generating wasteful power consumption.

One of the objects of the present invention is a relay station, a base station, a mobile communication system, a backhaul link control method, and a program capable of contributing to efficient use of frequency resources in a mobile communication system including the relay station Is to provide.

The first aspect includes a relay station. The relay station includes a radio communication unit and a backhaul link control unit. The wireless communication unit relays data between the base station and the mobile station using a backhaul link connected to the base station and an access link connected to the mobile station. The backhaul link control unit switches a use frequency of the backhaul link during operation of a relay station cell using the access link. Here, the use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to the out-band frequency different from the use frequency of the access link, and from the out-band frequency. Including at least one of switching to the in-band frequency.

The second aspect includes a base station. The base station includes a radio communication unit and a backhaul link control unit. The wireless communication unit is configured to be able to perform data transfer with a mobile station connected to the relay station via an access link via a backhaul link connected to the relay station. The backhaul link control unit switches the use frequency of the backhaul link during operation of the relay station cell using the access link by the relay station. Here, the use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to the out-band frequency different from the use frequency of the access link, and from the out-band frequency. Including at least one of switching to the in-band frequency.

The third aspect includes a mobile communication system including a base station and a mobile station. The relay station relays data between the base station and the mobile station using a backhaul link connected to the base station and an access link connected to the mobile station. Furthermore, the mobile communication system according to this aspect is configured to be able to switch the use frequency of the backhaul link during operation of the relay station cell using the access link by the relay station. Here, the use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to the out-band frequency different from the use frequency of the access link, and from the out-band frequency. Including at least one of switching to the in-band frequency.

The fourth aspect includes a backhaul link control method for connecting a base station and a mobile station. Here, the relay station is configured to perform data relay between the base station and the mobile station using the backhaul link and an access link connected to the mobile station. The method according to the present aspect includes switching a use frequency of the backhaul link during operation of a relay station cell using an access link connecting the relay station and a mobile station. Here, switching the use frequency of the backhaul link includes switching from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and the out-band frequency. To at least one of switching to the in-band frequency.

The fifth aspect includes a program for causing a computer to perform the method according to the fourth aspect described above.

According to each aspect described above, a relay station, a base station, a mobile communication system, a backhaul link control method, and a program capable of contributing to efficient use of frequency resources in a mobile communication system including a relay station are provided. Can be provided.

It is a block diagram which shows the structural example of the mobile communication system which concerns on background art. It is a sequence diagram which shows the startup procedure of the relay station which concerns on background art. FIG. 2 is a block diagram showing a configuration example of a mobile communication system according to the first embodiment. 3 is a block diagram showing a configuration example of a base station in the first embodiment. FIG. 3 is a block diagram illustrating a configuration example of a relay station in Embodiment 1. FIG. 3 is a block diagram showing a configuration example of a mobile station in Embodiment 1. FIG. FIG. 4 is a sequence diagram showing an example of a backhaul link control procedure in the first embodiment. 3 is a flowchart showing an operation example of a relay station in the first embodiment. 3 is a flowchart showing an operation example of a base station in the first embodiment. FIG. 10 is a sequence diagram showing an example of a backhaul link control procedure in the second embodiment. 6 is a flowchart illustrating an operation example of a relay station in the second embodiment. 6 is a flowchart showing an operation example of a base station in the second embodiment. FIG. 11 is a sequence diagram showing an example of a backhaul link control procedure in the third embodiment. 12 is a flowchart illustrating an operation example of a relay station in the third embodiment. 10 is a flowchart showing an operation example of a base station in the third embodiment. FIG. 10 is a block diagram illustrating a configuration example of a management device according to a fourth embodiment. FIG. 10 is a sequence diagram showing an example of a backhaul link control procedure in the fourth embodiment. 10 is a flowchart illustrating an operation example of the management device according to the fourth embodiment.

Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted as necessary for clarification of the description.

<Embodiment 1>
FIG. 3 is a block diagram showing a configuration example of the mobile communication system according to the present embodiment. The radio communication system according to the present embodiment will be described as an FDD (Frequency division Duplex) -OFDMA, more specifically, an LTE-Advanced radio communication system based on the LTE scheme. In FIG. 3, the base station (eNB) 1 belongs to the mobile carrier's core network (CN) 4, and is between the mobile station (eNB-UE) 3-1 and the core network (CN) 4. To relay traffic. The base station 1 is a base station that can accept the attribution of the relay station 2 (that is, a base station that can operate as a DeNB), and can also accept the attribution of the mobile station 3-1.

Relay station (RN) 2 connects base station 1 and the backhaul link (BL1 in FIG. 3). Further, the relay station (RN) 2 operates the relay station cell 20 using the access link (AL2 in FIG. 3), and connects to the mobile station (RN-UE) 3-2 through the access link (AL2). Data relay is performed between the base station 1 and the mobile station 3-2. In the present embodiment, the relay station 2 can be connected to the management apparatus 5 via the core network (CN) 4. The management device 5 is an OAM system and manages information set by a mobile communication carrier. The relay station 2 can acquire information (i.e. donor cell list) from the management device 5, and performs initial setting of the backhaul link and the access link according to the RN startup procedure described in Non-Patent Document 3. Note that the procedure for performing the initial setting of the relay station 2 using the information (i.e. donor cell list) distributed from the management device 5 is merely a request based on the LTE standard. That is, the relay station 2 can perform initial setting without performing communication with the management device 5. In this case, information relating to the initial setting of the relay station 2 may be stored in advance in a storage device in the relay station 2. Further, information regarding the initial setting of the relay station 2 may be transmitted from the base station 1 to the relay station 2.

In the mobile communication system according to the present embodiment, relay station 2 and base station 1 connect a backhaul link (BL1), and relay station 2 operates relay station cell 20 using an access link (AL2). In the state, the operating frequency of the backhaul link (BL1) (hereinafter referred to as the backhaul link frequency) can be switched. Here, switching of the backhaul link frequency is the same frequency (hereinafter referred to as in-band frequency) as the frequency used for the access link (AL2) to a frequency different from the frequency used for the access link (AL2) (hereinafter referred to as out-band frequency). And at least one of switching from an out-band frequency to an in-band frequency.

In other words, in the mobile communication system according to the present embodiment, in the state where the relay station 2 is operating the relay station cell 20 using the access link (AL2), the operation state of the backhaul link (BL1) is in- It is possible to switch from band operation to out-band operation, or from out-band operation to in-band operation.

The determination of switching of the backhaul link frequency, that is, the determination of the switching condition of the backhaul link frequency may be performed by the relay station 2 or the base station 1. Further, the switching of the backhaul link frequency may be determined by another device (higher level device) in the mobile communication system, or may be performed by an OAM system that monitors the mobile communication system. That is, the determination subject of the switching condition of the backhaul link frequency may be appropriately determined according to the switching condition to be used. When the determination of the switching condition of the backhaul link frequency is performed by the host device or the OAM system, the relay station 2 or the base station 1 or both have information necessary for the determination (eg, the traffic information of the relay station cell 20, the base station The traffic information of the cell 10, the power consumption information of the base station 1, etc.) may be reported to the host device or the OAM system. The host device or the OAM system may determine switching of the backhaul link frequency with reference to information received from the relay station 2 or the base station 1 or both.

There are various variations in the switching conditions of the backhaul link frequency. Specific examples of conditions for switching the backhaul link frequency include (a) traffic volume processed by relay station 2, (b) traffic volume processed by donor base station 1, (c) time zone, and (d) relay station 2 And power consumption of at least a part of the mobile communication system including the base station 1. Hereinafter, these specific examples will be described in order.

(A-1) Traffic volume processed by relay station 2 The mobile communication system according to the present embodiment is provided with a backhaul link on condition that the traffic volume processed by relay station 2 decreases during out-band operation. The frequency may be switched from the out-band frequency to the in-band frequency. For example, the mobile communication system may switch the backhaul link frequency from the out-band frequency to the in-band frequency when it is determined that the traffic volume processed by the relay station 2 falls below a predetermined threshold.

The amount of traffic processed by the relay station 2 is, for example, the amount of data packets transferred to the access link (AL2), the amount of data packets transferred through the backhaul link (BL1), or the mobile station 3 connected to the relay station cell 20 It may be calculated using the total number of -2, or a combination of at least two of these. The traffic amount processed by the relay station 2 may be calculated by the relay station 2, the base station 1, other devices in the mobile communication system, or the OAM server.

In-band operation generally has more frequency resource restrictions than out-band operation, so the amount of traffic that can be processed by base station 1 and relay station 2 is limited. However, when the amount of traffic processed by the relay station 2 is small, the amount of traffic to be processed by the base station 1 and the relay station 2 is also small. For this reason, it is preferable to switch from out-band operation to in-band operation according to the phenomenon of traffic volume processed by the relay station 2. In-band operation uses the same frequency (for example, RF1) for the backhaul link (BL1) and the access link (AL1 and AL2). For this reason, the mobile communication system can efficiently use frequency resources. Further, by switching from the out-band operation to the in-band operation, the base station 1 can stop radio transmission at an unused frequency (for example, RF2). Therefore, it is possible to contribute to reduction of power consumption of the base station 1.

(A-2) Traffic volume processed by relay station 2 The mobile communication system according to the present embodiment is provided with a backhaul link on condition that the traffic volume processed by relay station 2 has increased during in-band operation. The frequency may be switched from the in-band frequency to the out-band frequency. For example, the mobile communication system may switch the backhaul link frequency from the in-band frequency to the out-band frequency when it is determined that the traffic volume processed by the relay station 2 exceeds a predetermined threshold. Thus, the radio communication system can efficiently use frequency resources by in-band operation when traffic is low, and can cope with traffic increase by switching to out-band operation.

(B) Traffic volume processed by base station 1 The mobile communication system according to the present embodiment changes the backhaul link frequency from the out-band frequency to the in-band frequency on the condition that the traffic volume processed by the base station 1 has decreased. You may switch to the band frequency. Also, the mobile communication system according to the present embodiment may switch the backhaul link frequency from the in-band frequency to the out-band frequency on condition that the traffic volume processed by the base station 1 has increased.

Further, the mobile communication system according to the present embodiment may switch between out-band operation and in-band operation on condition that the total amount of traffic processed by relay station 2 and base station 1 has fluctuated. Good. That is, the backhaul link frequency may be switched from the out-band frequency to the in-band frequency on the condition that the total traffic volume has decreased. Also, the backhaul link frequency may be switched from the in-band frequency to the out-band frequency on condition that the total traffic volume has increased.

(C) Time zone The mobile communication system according to the present embodiment may switch between out-band operation and in-band operation according to the time zone. That is, the mobile communication system according to the present embodiment uses an out-band frequency for the backhaul link (BL1) in a predetermined first time zone, and backhauls in a predetermined second time zone. An in-band frequency may be used for the link (BL1).

Here, the second time zone may be a time zone in which the amount of traffic to be processed by the relay station 2 or the base station 1 is assumed to be smaller than that of the first time zone. Specifically, the second time zone may be nighttime and the first time zone may be daytime. As a result, the wireless communication system can perform in-band operation when the traffic is low, and thus can efficiently use frequency resources.

Also, the operator of the mobile communication system may set the second time zone as a time zone in which the power consumption of the base station 1 is desired to be suppressed. Thereby, the radio | wireless communications system can perform in-band operation in the 2nd time slot | zone which should suppress the power consumption of the base station 1, and can contribute to reduction of power consumption.

(D) Power consumption of at least part of mobile communication system The mobile communication system according to the present embodiment includes a base station 1, a plurality of base stations including base station 1, relay station 2, or relay station 2 and base station 1 For example, the backhaul link frequency may be switched from the out-band frequency to the in-band frequency on condition that power consumption of at least a part of the mobile communication system has increased. The wireless communication system can suppress power consumption of the mobile communication system by switching from out-band operation to in-band operation.

Hereinafter, a specific example of the configuration of the mobile communication system and the backhaul link frequency switching operation according to the present embodiment will be described in detail. FIG. 4 is a block diagram showing a configuration example of the base station 1. As shown in FIG. In FIG. 4, the radio communication unit 11 receives an uplink signal transmitted from the mobile station 3-1 or the relay station 2 via an antenna. The reception data processing unit 13 restores the received uplink signal. The obtained received data is transferred to the core network 4 via the communication unit 14. The transmission data processing unit 12 stores the data acquired from the communication unit 14 for the mobile stations 3-1, 3-2 or the relay station 2 in a buffer set for each mobile station and for each bearer, error correction coding, A transport channel is generated by performing rate matching, interleaving, and the like. Further, the transmission data processing unit 12 adds a control information to the data sequence of the transport channel to generate a radio frame.

The wireless communication unit 11 performs a process such as orthogonal modulation, frequency conversion, and signal amplification of the transmission symbol sequence to generate a downlink signal, and transmits this to the mobile station 3-1 or the relay station 2. The backhaul link control unit 15 controls transmission timing related to communication with the relay station 2 via the backhaul link, radio resource allocation, and a frequency used in the backhaul link.

FIG. 5 is a block diagram showing a configuration example of the relay station 2. The relay station 2 has a function equivalent to that of the base station 1 unless otherwise specified. In FIG. 5, the lower radio link communication unit 21 receives an uplink signal transmitted from the mobile station 3-2 via an antenna. The reception data processing unit 23 has both functions of a reception data processing unit 13 of the base station 1 and a transmission data processing unit 34 of the mobile station 3 described later. The reception data obtained by the reception data processing unit 23 is transmitted to the base station 1 via the upper radio link communication unit 24.

The transmission data processing unit 22 has both functions of a transmission data processing unit 12 of the base station 1 and a reception data processing unit 32 of the mobile station 3 described later. The transmission data processing unit 22 generates a transmission symbol sequence from the transmission data transmitted toward the mobile station 3-2 acquired from the upper radio link communication unit 24. The lower radio link communication unit 21 generates a downlink signal from the symbol string and transmits it to the mobile station 3-2.

The backhaul link control unit 25 performs communication control with the base station via the backhaul link such as selection of a frequency used for the backhaul link.

FIG. 6 is a block diagram illustrating a configuration example of the mobile station 3. The wireless communication unit 31 receives a downlink signal via an antenna. The received data processing unit 32 restores the received data from the received downlink signal and sends it to the buffer unit 35. The received data stored in the buffer unit 35 is read out and used according to its purpose. Further, the transmission data control unit 33, the transmission data processing unit 34, and the wireless communication unit 31 generate an uplink signal using the transmission data stored in the buffer unit 35, and transmit it to the base station 1 or the relay station 2 To do.

Subsequently, a specific example of the procedure for switching the backhaul link frequency in this embodiment will be described below with reference to FIGS. Note that the specific example described with reference to FIGS. 7 to 9 relates to an example in which the relay station 2 determines the switching condition of the backhaul link frequency. FIG. 7 is a sequence diagram showing an example of a backhaul link control procedure in the first embodiment. FIG. 7 shows the interaction between the base station 1, the relay station 2, and the mobile stations 3-1 and 3-2, where “eNB” is the base station 1, “RN” is the relay station 2, and “RN” -UE "corresponds to mobile station 3-2 belonging to RN, and" eNB-UE "corresponds to mobile station 3-1 belonging to eNB including DeNB.

Steps S101 to S103 show data communication between eNB 1, RN 2, UE 3-1 and 3-2 in out-band operation. Specifically, the eNB 1 and the RN 2 perform data communication using the frequency RF2 as the backhaul link frequency (step S101). The RN 2 and RN-UE 3-2 perform data communication using the frequency RF1 as the frequency of the access link (AL2) (step S102). The eNB 1 and eNB-UE 3-1 perform data communication using the frequency RF1 as the frequency of the access link (AL1) (step S103).

In step S104, RN 2 decides switching of the backhaul link frequency, here switching from the out-band frequency RF2 to the in-band frequency RF1. The determination may be performed using any of the above-described switching conditions of the backhaul link frequency. For example, the RN 2 monitors the traffic of the RN cell 20. Then, the RN 2 may determine switching to the in-band frequency when the traffic volume of the RN cell 20 falls below a preset threshold value.

In step S105, RN 2 transmits a request for changing the frequency used in the backhaul link to eNB 1. In Step S106, the eNB 1 instructs the RN 2 to change the backhaul link setting (frequency, presence / absence of resource division, etc.) in response to receiving the backhaul link frequency change request. Here, when the frequency RF2 becomes unused due to switching to in-band operation, the eNB-1 may stop radio transmission at the frequency RF2.

In step S107, RN 2 changes the setting of the backhaul link including frequency switching based on the backhaul link change instruction from eNB 1 (step S107). Steps S108 to S110 show data communication between eNB 1, RN 2, UE 3-1 and 3-2 after switching the backhaul link frequency, that is, after switching from out-band operation to in-band operation. ing. The eNB 1 and the RN デ ー タ 2 perform data communication using the frequency RF1 as the backhaul link frequency (step S108). The RN 2 and the RN-UE 3-2 perform data communication using the frequency RF1 as the frequency of the access link (AL2) (step S109). The eNB 1 and eNB-UE 3-1 perform data communication using the frequency RF1 as the frequency of the access link (AL1) (step S110).

FIG. 8 is a flowchart showing an operation example of the relay station 2 regarding switching of the backhaul link frequency. In step S201, the relay station 2 determines switching of the backhaul link frequency. When switching of the backhaul link frequency is not performed (No in Step S201), the relay station 2 returns to Step S201 for determining switching of the backhaul link frequency. When switching of the backhaul link frequency is determined (Yes in Step S201), the relay station 2 transmits a backhaul link change request to the base station 1 (Step S202).

In step S203, the relay station 2 determines whether a backhaul link change request has been received from the base station 1. When the backhaul link change request is received (Yes in Step S203), the relay station 2 changes the setting of the backhaul link including switching of the backhaul link frequency (Step S204). When the backhaul link change request has not been received (No in Step S203), the relay station 2 returns to Step S203 for determining whether or not the backhaul link change request has been received.

FIG. 9 is a flowchart showing an operation example of the base station 1 regarding switching of the backhaul link frequency. In step S301, the base station 1 determines whether or not a backhaul link change request has been received. When the backhaul link change request is received (Yes in Step S301), the base station 1 transmits the backhaul link change request to the relay station 2 (Step S302). When the backhaul link change request has not been received (No in Step S301), the base station 1 returns to Step S301 for determining reception of the backhaul link change request. In step S303, the base station 1 stops radio transmission at this frequency when an unused frequency is generated due to switching of the backhaul link frequency, particularly switching from the out-band frequency to the in-band frequency. To do.

As described above, in the mobile communication system according to the present embodiment, in the state where the relay station 2 is operating the relay station cell 20 using the access link (AL2), the frequency used for the backhaul link (BL1) ( Hereinafter, the backhaul link frequency) can be switched. For this reason, the mobile communication system can efficiently use frequency resources. Further, by switching from the out-band operation to the in-band operation, the base station 1 can stop radio transmission at an unused frequency (for example, RF2). Therefore, it is possible to contribute to reduction of power consumption of the base station 1.

<Embodiment 2>
In this embodiment, a modification of backhaul link control including switching of the backhaul link frequency described in Embodiment 1 will be described. Specifically, after switching the backhaul link frequency, the mobile communication system according to the present embodiment returns the backhaul link frequency before switching in accordance with the deterioration of radio parameters of relay station cell 20. The radio parameter of the relay station cell 20 can be rephrased as the communication quality of the relay station cell 20. A specific example of the radio parameter of the relay station cell 20 is the downlink throughput (data amount that can be transmitted per unit time) of the RN cell 20, or the number of mobile stations that can be connected to the RN cell 20. For example, the mobile communication system may switch back the backhaul link frequency when the difference (decrease width) in throughput before and after switching the backhaul link frequency exceeds a predetermined threshold. Further, the mobile communication system may switch back the backhaul link frequency when the throughput after switching the backhaul link frequency falls below a predetermined threshold.

The decision of switching backhaul link frequency may be made by the relay station 2 or the base station 1. In addition, the determination of backhaul link frequency switching may be performed by another device (higher-order device) in the mobile communication system, or by an OAM system that monitors the mobile communication system. In other words, the determination subject of the backhaul link frequency switch-back may be appropriately determined according to the frequency switch-back condition.

That is, in the mobile communication system according to the present embodiment, when the switching of the backhaul link frequency causes the communication quality (eg, throughput) of the relay station cell 20 to deteriorate, the switching operation for returning the backhaul link frequency to the original state I do. Therefore, it is possible to contribute to efficient use of frequency resources and reduction of power consumption of the base station 1 while suppressing deterioration of communication quality of the RN cell 20.

Hereinafter, a specific example of the backhaul link frequency switching and switching back procedure according to the present embodiment will be described with reference to FIGS. The specific example described with reference to FIGS. 10 to 12 relates to an example in which the relay station 2 determines the backhaul link frequency switchback. FIG. 10 is a sequence diagram showing an example of a backhaul link control procedure in the second embodiment. Processes and operations from step S101 to step S110 in FIG. 10 are the same as the step group having the same reference numerals in FIG. 7 described in the first embodiment. Therefore, only the difference from FIG. 7 will be described here.

In step S401 after changing the setting of the backhaul link, the RN 2 measures whether or not the radio parameter (in other words, communication quality) of the RN cell 20 has deteriorated. When detecting the deterioration of the radio parameter, the RN 2 transmits a backhaul link recovery request to the eNB 1 in order to return the backhaul link setting including the backhaul link frequency before switching (step S402). In step S403, the eNB を 1 instructs the RN 2 to change the backhaul link setting (frequency, presence / absence of resource division, etc.) in response to receiving the recovery request. In addition, when the radio transmission at the frequency before the switching is stopped, the eNB 1 restarts the radio transmission at the frequency before the switching.

In step S404, RN2 restores the backhaul link setting in response to receiving the backhaul link change instruction. The data communication before the change is restored (from step S101 to step S103). Steps S405 to S407 perform data communication between eNB 1, RN 2, UE 3-1 and 3-2 after switching backhaul link frequency, that is, after switching from in-band operation to out-band operation. Show. Accordingly, steps S405 to S407 are the same as steps S101 to S103.

FIG. 11 is a flowchart showing an operation example of the relay station 2 regarding switching and switching backhaul link frequencies. Processes and operations from step S201 to step S204 in FIG. 11 are the same as those in the step group having the same reference numerals in FIG. 8 described in the first embodiment. Therefore, only the difference from FIG. 8 will be described here.

In step S501 after switching the backhaul link frequency, the relay station 2 determines whether or not the radio parameters of the relay station cell 20 have deteriorated. If the radio parameter has not deteriorated (No in step S501), the relay station 2 ends the procedure of FIG. On the other hand, when the radio parameter is degraded (Yes in step S501), the relay station 2 transmits a backhaul link recovery request to the DeNB for switching back the backhaul link frequency (step S502). In step S503, the relay station 2 determines whether a backhaul link change request has been received from the base station 1. When the backhaul link change request is received (Yes in Step S503), the relay station 2 changes the setting of the backhaul link including switching back of the backhaul link frequency (Step S504). When the backhaul link change request has not been received (No in Step S503), the relay station 2 returns to Step S503 for determining whether or not the backhaul link change request has been received.

FIG. 12 is a flowchart showing an operation example of the base station 1 regarding backhaul link frequency switching back. In step S601, the base station 1 determines whether or not a backhaul link recovery request has been received from the relay station 2. When the backhaul link recovery request is received (Yes in step S601), the base station 1 instructs the RN to change the setting of the backhaul link including the backhaul link frequency switch back (step S602). If the backhaul link recovery request has not been received (No in step S601), the base station 1 returns to step S601 to determine whether or not a backhaul link recovery request has been received.

<Embodiment 3>
In this embodiment, a modification of backhaul link control including switching of the backhaul link frequency described in Embodiment 1 will be described. Specifically, in the mobile communication system according to the present embodiment, after switching the backhaul link frequency, the radio parameter of the relay station cell 20 is changed according to the deterioration of the deterioration being smaller than the reference. Stop operation. For example, the mobile communication system may stop the operation of the relay station cell 20 when the throughput difference (decrease width) before and after the switching of the backhaul link frequency falls below a predetermined threshold. Also, the mobile communication system may stop the operation of the relay station cell 20 when the throughput after switching the backhaul link frequency exceeds a predetermined threshold.

The decision to stop operation of the relay station cell 20 may be made by the relay station 2 or the base station 1. In addition, the operation stop determination of the relay station cell 20 may be performed by another device (higher-order device) in the mobile communication system, or may be performed by an OAM system that monitors the mobile communication system. That is, the determination subject of the operation stop of the relay station cell 20 may be appropriately determined according to the operation stop condition of the relay station cell 20.

That is, the mobile communication system according to the present embodiment stops the operation of the relay station cell 20 when the deterioration of the communication quality of the relay station cell 20 after switching of the backhaul link frequency is small. Therefore, in addition to the efficient use of frequency resources and the reduction of power consumption of the base station 1, it can also contribute to the reduction of power consumption of the relay station 2.

Hereinafter, a specific example of the backhaul link frequency switching and the operation stop procedure of the relay station cell 20 in the present embodiment will be described with reference to FIGS. Note that the specific example described with reference to FIGS. 13 to 15 relates to an example in which the relay station 2 determines to stop the operation of the relay station cell 20. FIG. 13 is a sequence diagram showing an example of a backhaul link control procedure in the third embodiment. Processes and operations from step S101 to step S110 in FIG. 13 are the same as those in the step group having the same reference numerals in FIG. 7 described in the first embodiment. Therefore, only the difference from FIG. 7 will be described here.

In Step S701 after changing the setting of the backhaul link, the RN 2 measures whether or not the radio parameter (in other words, communication quality) of the RN cell 20 has deteriorated. If the degradation of the line parameter is below the reference, the RN 2 transmits an RN cell suspension notification to the eNB 1 in order to suspend the RN cell 20 (step S702). In step S703, the eNB 1 stops data transmission addressed to the RN 2 in response to receiving the RN cell suspension notification (step S703). The RN 2 suspends the operation of the RN cell 20 after transmitting the RN cell suspension notification (step S704). Steps S705 and S706 indicate data communication after the RN cell 20 is suspended. That is, the RN-UE 3-2 connected to the RN cell 20 before suspending the RN cell directly belongs to the eNB cell 10 through the access link (AL1) and performs data communication.

FIG. 14 is a flowchart showing an operation example of the relay station 2 regarding switching of the backhaul link frequency and suspension of operation of the relay station cell 20. Processes and operations from step S201 to step S204 in FIG. 14 are the same as those in the step group having the same reference numerals in FIG. 8 described in the first embodiment. Therefore, only the difference from FIG. 8 will be described here.

In step S801 after switching the backhaul link frequency, the relay station 2 determines whether or not the radio parameters of the relay station cell 20 have deteriorated. If the degradation of the radio parameters exceeds the standard (No in step S801), the relay station 2 ends the procedure of FIG. On the other hand, when the degradation of the radio parameter is below the reference (Yes in step S801), the relay station 2 transmits a relay station cell suspension notification to the base station 1 (step S802). In step S803, the relay station 2 stops the operation of the relay station cell 20.

FIG. 15 is a flowchart showing an operation example of the base station 1 regarding the suspension of operation of the relay station cell 20. In step S901, the base station 1 determines whether or not a relay station cell suspension notification is received from the relay station 2. When the relay station cell suspension notification is received (Yes in step S901), the base station 1 stops data transmission to the relay station 2 (step S902). When the relay station cell suspension notification is not received (No in step S901), the base station 1 returns to step S901 for determining reception of the relay station cell suspension notification.

<Embodiment 4>
In this embodiment, a specific example of a backhaul link frequency switching procedure taking into account the power consumption of the mobile communication system described in Embodiment 1 will be described. Specifically, the mobile communication system according to the present embodiment monitors the total power consumption of the plurality of base stations 1 or the plurality of relay stations 2 or both in the management apparatus 5, and responds to the increase in the total power consumption. Switch backhaul link frequency from out-band frequency to in-band frequency. Node groups (base stations and relay stations) to be monitored may be determined according to their geographical arrangement.

The mobile communication system according to the present embodiment can switch the backhaul link frequency in consideration of the total power consumption of a plurality of nodes included in the mobile communication system. Therefore, the suppression of the power consumption of the base station 1 can contribute to the suppression of the total power consumption of a plurality of nodes.

Hereinafter, a specific example of the configuration of the mobile communication system and the backhaul link frequency switching operation according to the present embodiment will be described in detail. The configuration examples of the base station 1, the relay station 2, and the mobile station 3 may be the same as those shown in FIGS.

FIG. 16 is a block diagram showing a configuration example of the management apparatus 5 in the present embodiment. The communication unit 51 transmits and receives data packets between the base station 1 and the relay station 2 via the core network 4. The reception data processing unit 53 restores information included in the received uplink data packet. When the restored information is information regarding power consumption, the reception data processing unit 53 sends this to the backhaul link management unit 54. The backhaul link management unit 54 manages the frequency used for the backhaul link, the power consumption of the plurality of base stations 1, and the like. Further, the backhaul link management unit 54 instructs the change of the backhaul link frequency according to the total power consumption of the plurality of base stations 1 to be managed. When the transmission data processing unit 52 receives control information related to the backhaul link frequency from the backhaul link management unit 54, the transmission data processing unit 52 transmits the control information to the corresponding base station 1 and relay station 2.

Subsequently, a specific example of the procedure for switching the backhaul link frequency in the present embodiment will be described below with reference to FIGS. FIG. 17 is a sequence diagram showing an example of a backhaul link control procedure in the fourth embodiment. The sequence in FIG. 17 is different from the sequence in FIG. 7 in that the determination subject of the backhaul frequency is not the RN 2 but the management device 5. Accordingly, the processes and operations in steps S101 to S103 and steps S106 to S110 in FIG. 17 are the same as those in the step group having the same reference numerals shown in FIG. Therefore, only the difference from FIG. 7 will be described here.

In step S1101, eNB 1 notifies the management device 5 (i.e. OAM server) of information (e.g. power consumption or power usage rate) regarding the power consumption of eNB 1. This notification may be performed periodically at a predetermined cycle, or may be performed when power consumption exceeds a reference. In step S1102, the management device 5 aggregates the power consumption information received from the plurality of eNBs 1 and controls the power consumption. Specifically, when the total power consumption of the plurality of eNB 1 exceeds a predetermined reference level, the management device 5 identifies the eNB 1 having an out-band operation backhaul link, and the eNB 1 A backhaul link change request is transmitted to (step S1103). This backhaul link change request includes an instruction to switch the backhaul frequency to the in-band frequency. Note that when the eNBe1 is specified, the management device 5 changes the backhaul link to in-band operation to generate a frequency that does not require data transmission, and can stop transmission at this frequency. You may choose eNB 1.

FIG. 18 is a flowchart showing an operation example of the management apparatus 5 related to switching of the backhaul link frequency in the fourth embodiment. In step S1201, the management device 5 receives power consumption information from the plurality of base stations 1. In step S1202, the management device 5 determines whether or not the total power consumption of the plurality of base stations 1 exceeds the reference level. When the total power consumption exceeds the reference level (Yes in step S1202), the management apparatus 5 identifies the base station 1 and the relay station 2 that should change the backhaul link for out-band operation, and changes the backhaul link. Send a request. This frequency is changed from the out-band frequency to the in-band frequency.

As described above, in the mobile communication system according to the present embodiment, the management apparatus 5 collects power consumption information of a plurality of base stations 1 and selects the base station 1 whose configuration of the backhaul link should be changed. For this reason, it is possible to suppress power consumption in consideration of the plurality of base stations 1 or the entire mobile communication system.

In the present embodiment, an example of controlling the backhaul link based on the total power consumption of a plurality of base stations 1 has been shown, but the total amount of power consumption including equipment that uses electricity other than the base station 1 The backhaul link may be controlled based on a ratio (usage rate) to the maximum power consumption. For example, the management device 5 monitors power consumption information of electronic devices such as server computers as well as a plurality of base stations 1, and changes the backhaul link configuration when the total power consumption exceeds a reference level Good. Further, when the ratio (usage rate) to the maximum power consumption is used as the power consumption information, the base station 1 may notify the management device 5 of its own power usage rate. The management device 5 may change the configuration of the backhaul link when the number of base stations whose power usage rate is higher than the threshold is equal to or greater than a predetermined number.

<Other embodiments>
In Embodiments 1 to 4 described above, mobile communication systems that support LTE relay stations have been described. However, the application destination of these embodiments is not limited to a mobile communication system that supports LTE relay stations. That is, these embodiments are widely applicable to mobile communication systems including relay stations.

Regarding the procedure for changing the backhaul link frequency described in Embodiments 1 to 4, the base station 1, the relay station 2, other devices included in the mobile communication system, or the processing / operations performed by the management device 5, Any of them may be realized by using a semiconductor processing apparatus including ASIC (Application Specific Specific Integrated Circuit). Further, these processes may be realized by causing a computer such as a microprocessor or DSP (Digital Signal Processor) to execute a program. Specifically, a program including an instruction group for causing a computer to execute at least one of the algorithms related to each node described with reference to FIGS. 7 to 15 and FIGS. 17 to 18 is created, and the program is stored in the computer. What is necessary is just to supply.

This program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include various types of tangible storage media (tangible storage medium). Examples of non-transitory computer-readable media include magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical discs), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable ROM), flash ROM, RAM (random access memory)) are included. The program may also be supplied to the computer by various types of temporary computer-readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

Further, Embodiments 1 to 4 can be appropriately combined. Furthermore, the above-described embodiment is merely an example relating to application of the technical idea obtained by the present inventors. That is, the technical idea is not limited to the above-described embodiment, and various changes can be made.

This application claims priority based on Japanese Patent Application No. 2011-175925 filed on Aug. 11, 2011, the entire disclosure of which is incorporated herein.

DESCRIPTION OF SYMBOLS 1 Base station 2 Relay station 3 Mobile station 4 Core network 5 Base station control apparatus 11 Wireless communication part 12 Transmission data processing part 13 Reception data processing part 14 Communication part 15 Backhaul link control part 21 Lower radio | wireless link wireless communication part 22 Transmission data Processing unit 23 Reception data processing unit 24 Upper wireless link communication unit 25 Backhaul link control unit 31 Wireless communication unit 32 Reception data processing unit 33 Transmission data control unit 34 Transmission data processing unit 35 Buffer unit 51 Communication unit 52 Transmission data processing unit 53 Received data processing unit 54 Backhaul link management unit

Claims (45)

1. Wireless communication means for relaying data between the base station and the mobile station using a backhaul link connected to the base station and an access link connected to the mobile station;
   Backhaul link control means for switching the use frequency of the backhaul link during operation of the relay station cell using the access link;
   With
   The use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and from the out-band frequency to the in-band frequency. A relay station that includes at least one of switching to a band frequency.
2. The backhaul link control means includes (a) a first traffic volume processed by the relay station, (b) a second traffic volume processed by the base station, (c) a time zone, and (d) the relay The relay station according to claim 1, wherein the use frequency of the backhaul link is switched based on a predetermined condition regarding at least one of power consumption of at least a part of a mobile communication system including a station and the base station.
3. The backhaul link control means determines the in-band frequency from the out-band frequency in response to a decrease in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The relay station according to claim 2, wherein the relay station switches to a -band frequency.
4. The backhaul link control means is configured to output the out-band frequency from the in-band frequency in response to an increase in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The relay station according to claim 2 or 3, wherein switching to a -band frequency is performed.
5. The backhaul link control means uses the out-band frequency for the backhaul link in a first time zone and uses the in-band frequency for the backhaul link in a second time zone. 2. The relay station according to 2.
6. The backhaul link control means performs switching from the out-band frequency to the in-band frequency in response to an increase in power consumption of at least a part of the mobile communication system. Relay station.
7. The backhaul link control means has received an instruction message from the base station, a device arranged in the mobile communication system, or an OAM (Operation Administration and Maintenance) system that has determined that the predetermined condition has been established. The relay station according to any one of claims 2 to 6, wherein the use frequency of the backhaul link is switched accordingly.
8. The relay station according to any one of claims 1 to 7, wherein the backhaul link control means transmits a frequency switching request for the backhaul link to the base station.
9. The backhaul link control means switches the use frequency of the backhaul link from the in-band frequency to the out-band frequency, or after switching from the out-band frequency to the in-band frequency. The relay station according to any one of claims 1 to 8, wherein a process of returning the use frequency of the backhaul link before switching is performed in accordance with deterioration of the radio parameter of
10. The relay station according to claim 9, wherein the backhaul link control means transmits a request for returning the use frequency of the backhaul link before switching to the base station.
11. The relay station according to claim 9, wherein the backhaul link control means performs a process of returning the use frequency of the backhaul link before switching in response to receiving a request from the base station.
12. The backhaul link control means, after switching the use frequency of the backhaul link from the out-band frequency to the in-band frequency, in accordance with the deterioration of the radio parameters of the relay station cell is smaller than the reference, The relay station according to any one of claims 1 to 11, wherein a process of stopping the operation of the relay station cell is performed.
13. The relay station according to claim 12, wherein the backhaul link control means transmits information on the suspension of operation of the relay station cell to the base station.
14. The relay station according to claim 12, wherein the backhaul link control means performs a process of stopping the operation of the relay station cell in response to receiving a request from the base station.
15. Via a backhaul link connected to the relay station, wireless communication means capable of performing data transfer with a mobile station connected to the relay station by an access link;
    Backhaul link control means for switching the use frequency of the backhaul link during operation of the relay station cell using the access link by the relay station;
    With
    The use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and from the out-band frequency to the in-band frequency. A base station including at least one of switching to a band frequency.
16. The backhaul link control means includes (a) a first traffic volume processed by the relay station, (b) a second traffic volume processed by the base station, (c) a time zone, and (d) the relay The base station according to claim 15, wherein the use frequency of the backhaul link is switched based on a predetermined condition regarding at least one of power consumption of at least a part of a mobile communication system including the station and the base station.
17. The backhaul link control means determines the in-band frequency from the out-band frequency in response to a decrease in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The base station according to claim 16, which performs switching to a -band frequency.
18. The backhaul link control means is configured to output the out-band frequency from the in-band frequency in response to an increase in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The base station according to claim 16 or 17, which performs switching to a -band frequency.
19. The backhaul link control means uses the out-band frequency for the backhaul link in a first time zone and uses the in-band frequency for the backhaul link in a second time zone. 16. A base station according to 16.
20. The backhaul link control means performs switching from the out-band frequency to the in-band frequency in response to an increase in power consumption of at least a part of the mobile communication system. base station.
21. The backhaul link control means has received an instruction message from the mobile station, a device arranged in the mobile communication system, or an OAM (Operation Administration and Maintenance) system that has determined the establishment of the predetermined condition. The base station according to any one of claims 16 to 20, wherein the use frequency of the backhaul link is switched accordingly.
22. The base station according to any one of claims 15 to 21, wherein the backhaul link control means transmits a frequency switching request for the backhaul link to the base station.
23. The backhaul link control means switches the use frequency of the backhaul link from the in-band frequency to the out-band frequency, or after switching from the out-band frequency to the in-band frequency. The base station according to any one of claims 15 to 22, wherein the base station performs processing for returning the use frequency of the backhaul link before switching in accordance with deterioration of the radio parameter.
24. The base station according to claim 23, wherein the backhaul link control means transmits a request for returning the use frequency of the backhaul link before switching to the relay station.
25. The base station according to claim 23, wherein the backhaul link control means performs a process of returning the use frequency of the backhaul link before switching in response to receiving a request from the relay station.
26. The backhaul link control means, after switching the use frequency of the backhaul link from the out-band frequency to the in-band frequency, in accordance with the deterioration of the radio parameters of the relay station cell is smaller than the reference, The base station according to any one of claims 15 to 25, wherein processing for stopping the operation of the relay station cell is performed.
27. 27. The base station according to claim 26, wherein the backhaul link control means transmits information related to suspension of operation of the relay station cell to the relay station.
28. The base station according to claim 26, wherein the backhaul link control means performs a process of stopping the operation of the relay station cell in response to receiving a request from the relay station.
29. A base station,
    A relay station that relays data between the base station and the mobile station using a backhaul link connected to the base station and an access link connected to the mobile station;
    Backhaul link control means for switching the use frequency of the backhaul link during operation of the relay station cell using the access link by the relay station;
    With
    The use frequency of the backhaul link is switched from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and from the out-band frequency to the in-band frequency. A mobile communication system including at least one of switching to a band frequency.
30. The backhaul link control means includes (a) a first traffic volume processed by the relay station, (b) a second traffic volume processed by the base station, (c) a time zone, and (d) the relay 30. The mobile communication system according to claim 29, wherein a use frequency of the backhaul link is switched based on a predetermined condition regarding at least one of power consumption of at least a part of a mobile communication system including a station and the base station. .
31. The backhaul link control means determines the in-band frequency from the out-band frequency in response to a decrease in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The mobile communication system according to claim 30, wherein switching to a -band frequency is performed.
32. The backhaul link control means is configured to output the out-band frequency from the in-band frequency in response to an increase in the first traffic volume, the second traffic volume, or a sum of the first and second traffic volumes. The mobile communication system according to claim 30 or 31, wherein switching to a -band frequency is performed.
33. The backhaul link control means uses the out-band frequency for the backhaul link in a first time zone and uses the in-band frequency for the backhaul link in a second time zone. 30. The mobile communication system according to 30.
34. The backhaul link control means performs switching from the out-band frequency to the in-band frequency in response to an increase in power consumption of at least a part of the mobile communication system. Mobile communication system.
35. The backhaul link control means switches the use frequency of the backhaul link from the in-band frequency to the out-band frequency, or after switching from the out-band frequency to the in-band frequency. The mobile communication system according to any one of claims 29 to 34, wherein a process of returning the use frequency of the backhaul link before switching is performed in accordance with deterioration of the radio parameter of
36. The backhaul link control means, after switching the use frequency of the backhaul link from the out-band frequency to the in-band frequency, in accordance with the deterioration of the radio parameters of the relay station cell is smaller than the reference, The mobile communication system according to any one of claims 29 to 35, wherein a process of stopping the operation of the relay station cell is performed.
37. The backhaul link control means includes at least one of a control unit arranged in the base station, a control unit arranged in the mobile station, and an OAM (Operation Administration and Maintenance) system. The mobile communication system according to any one of the above.
38. A backhaul link control method for connecting a base station and a mobile station,
    The relay station is configured to relay data between the base station and the mobile station using the backhaul link and an access link connected to the mobile station,
    The method comprises switching the use frequency of the backhaul link during operation of a relay station cell using an access link connecting the relay station and a mobile station,
    Switching the use frequency of the backhaul link includes switching from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and from the out-band frequency to the in-band frequency. including at least one of switching to -band frequency,
    Control method of backhaul link.
39. Switching the use frequency of the backhaul link includes (a) a first traffic volume processed by the relay station, (b) a second traffic volume processed by the base station, (c) a time zone, and ( d) switching the use frequency of the backhaul link based on a predetermined condition regarding at least one of power consumption of at least a part of a mobile communication system including the relay station and the base station. 38. The method according to 38.
40. Switching the use frequency of the backhaul link is based on the fact that the first traffic volume, the second traffic volume, or the sum of the first and second traffic volumes has decreased. 40. The method of claim 39, comprising switching from frequency to the in-band frequency.
41. Switching the use frequency of the backhaul link uses the out-band frequency for the backhaul link in a first time zone and uses the in-band frequency for the backhaul link in a second time zone. 40. The method of claim 39, comprising:
42. Switching the use frequency of the backhaul link includes switching from the out-band frequency to the in-band frequency in response to an increase in power consumption of at least a part of the mobile communication system. 40. The method of claim 39.
43. The radio parameter of the relay station cell has deteriorated after switching the use frequency of the backhaul link from the in-band frequency to the out-band frequency or from the out-band frequency to the in-band frequency. In response, the method of any one of claims 38 to 42, further comprising returning the used frequency of the backhaul link before switching.
44. After switching the use frequency of the backhaul link from the out-band frequency to the in-band frequency, the operation of the relay station cell is stopped in response to a deterioration in radio parameters of the relay station cell being smaller than a reference The method according to any one of claims 38 to 43, further comprising:
45. A non-transitory computer-readable medium storing a program for causing a computer to perform a control method of a backhaul link connecting a base station and a mobile station,
    The relay station is configured to relay data between the base station and the mobile station using the backhaul link and an access link connected to the mobile station,
    The method includes switching a use frequency of the backhaul link during operation of a relay station cell using an access link connecting the relay station and a mobile station,
    Switching the use frequency of the backhaul link includes switching from the same in-band frequency as the use frequency of the access link to an out-band frequency different from the use frequency of the access link, and from the out-band frequency to the in-band frequency. including at least one of switching to -band frequency,
    A non-transitory computer readable medium.

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