JP2011097142A - Mobile communication system, base station device, method for adjusting radio parameter, information transmission method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication system that facilitates updating of macrocell information by a macro base station or a host network and to enable a plurality of home base stations to use the updated macrocell information without causing significant delay when transmitting macrocell information to be used for radio parameter adjustment of a home cell by radio from a macro base station. <P>SOLUTION: The macro base station 6 transmits a downlink signal including the same cell information about a macrocell 12 a plurality of times. A home base station 1 receives a first radio signal including the same cell information at least one time, and validates macrocell information included in the received downlink signal until a predetermined time or until the lapse of a predetermined time. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile communication system including a home base station, and more particularly to a configuration of a cell formed by the home base station.

  Standardization organizations such as 3GPP (Third Generation Partnership Project) are working on standardization of small base stations that can be installed in users' homes and offices. The small base station is installed by a user in a home, a small office, or the like, and is connected to the core network through an access line which is a fixed line such as an ADSL (Asymmetric Digital Subscriber Line) or an optical fiber line. Such a small base station is generally called a femto base station, a femtocell base station, or a home base station. In addition, a cell formed by a small base station is extremely small compared to a conventional macro cell. For this reason, the cell which a small base station forms is called a femto cell or a home cell. A cell means a coverage area of a base station.

  3GPP defines such small base stations as Home Node B (HNB) and Home evolved Node B (HeNB) and is working on standardization work. HNB is a small base station for UTRAN (UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network), and HeNB is a small base station for LTE (Long Term Evolution) / E-UTRAN (Evolved UTRAN). In this specification, a small base station as described above is referred to as a “home base station”, and a cell formed by the home base station is referred to as a “home cell”. In addition, when referring to the home base station for UTRAN and E-UTRAN studied by 3GPP, HNB or HeNB, or these are collectively referred to as H (e) NB, following the name of 3GPP. A home cell formed by H (e) NB is referred to as an “H (e) NB cell”.

  In 3GPP Release 8, H (e) NB is standardized as a base station managed by a user (see Non-Patent Document 1). However, it is difficult for the user to appropriately set the configuration (radio frequency, scrambling code / physical cell ID, downlink transmission power, etc.) of the H (e) NB and H (e) NB cell. For this reason, there is concern that interference problems between the M (e) NB cell and the H (e) NB cell may occur due to the configuration of the H (e) NB cell not being performed properly. Yes. Here, the M (e) NB cell is a macro cell generated by M (e) NB (macro NodeB or macro eNodeB). In 3GPP Release 8, H (e) NB is required not to have a serious adverse effect on the performance of M (e) NB.

  In order to suppress interference between the H (e) NB cell and the M (e) NB cell, the H (e) NB has a function for autonomously setting radio parameters (referred to as self-configuration, auto-configuration, etc.). Has been considered to have. Here, the radio parameters are parameters that define the characteristics of radio communication. Specifically, the radio parameters include a radio frequency band, a scrambling code, a pilot signal (CPICH: Common Pilot Channel) transmission power, and a reference signal transmission. Power, maximum value of uplink transmission power by the mobile station, and the like. In addition, in order to perform autonomous self-configuration, it is considered that H (e) NB has a function to receive downlink signals from neighboring macro cells (called Network Listen Mode, Radio Environment Measurement, etc.). Yes.

3GPP TR 25.820 v8.2.0 (2008-09), "3G Home Node B (HNB) study item Technical Report"

  The inventor of the present application has studied in detail the autonomous cell configuration by M (e) NB. Whether or not the mobile station connected to the M (e) NB cell can withstand interference from the H (e) NB cell varies depending on the load status of the M (e) NB cell. When the load on the M (e) NB cell is large, when there are many mobile stations connected to the M (e) NB cell, or the level of interference from other nearby cells or other wireless systems For example, when it is large. In these cases, the mobile station connected to the M (e) NB cell is already in a state of being exposed to a large amount of interference or in a state of weak interference tolerance. For this reason, there is a possibility that the communication quality of the mobile station connected to the M (e) NB cell may deteriorate due to the additional interference from the H (e) NB cell.

  Based on the above consideration, the inventor of the present application wirelessly transmits information (macro cell information) on the M (e) NB cell from the M (e) NB, and the H (e) NB is received from the M (e) NB. A method for adjusting radio parameters for H (e) NB cells based on macro cell information was devised. The macro cell information may include, for example, information on radio resources used in the M (e) NB cell, the load status of the M (e) NB cell, and the like. It is considered that the interference from the H (e) NB cell to the M (e) NB cell can be effectively suppressed by adjusting the radio parameters related to the H (e) NB cell based on the macro cell information.

  When M (e) NB transmits macrocell information, it periodically transmits using broadcast channel (PBCH (Physical broadcast channel in the case of LTE)) or downlink shared channel (PDSCH (Physical downlink shared channel in the case of LTE)). It is possible to do. H (e) NB should just acquire the macrocell information transmitted regularly from M (e) NB, and may adjust the radio | wireless parameter of an own cell.

  However, in this adjustment method, the H (e) NB determines the reception timing of the macro cell information according to the communication status with the mobile station connected to the H (e) NB. That is, reception of macro cell information by H (e) NB is performed when H (e) NB is convenient. Therefore, when M (e) NB updates the contents of the macro cell information, H (e) NBs with different setting contents exist in the field depending on whether or not the updated macro cell information is received. For this reason, it is difficult to update the macro cell information at a timing convenient for the M (e) NB or the upper network by the initiative of the M (e) NB or the upper network.

  The present invention has been made based on the above-mentioned consideration by the inventors. That is, an object of the present invention is to provide a macro cell led by a macro base station or an upper network when transmitting macro cell information used for radio parameter adjustment of a home cell from a macro base station (M (e) NB in 3GPP). To provide a mobile communication system, a base station apparatus, a method, and a program that facilitate updating of information and contribute to the use of updated macro cell information by a plurality of home base stations without causing a large delay. is there.

  A mobile communication system according to a first aspect of the present invention includes a first base station capable of communicating with a mobile station by forming a first cell, and a mobile station by forming a second cell. A second base station that is capable of communicating with each other. The first base station can transmit the first radio signal including the same cell information regarding the first cell a plurality of times. The second base station receives a first radio signal including cell information related to the same first cell at least once, and receives the cell information included in the received first radio signal. Valid until the elapse of a predetermined time or until a predetermined time.

  The 2nd aspect of this invention is related with the base station apparatus which forms its own cell and performs radio | wireless communication between mobile stations. The base station apparatus includes a radio transmission / reception unit and a control unit. The said control part controls the said radio | wireless transmission / reception part so that the 1st radio signal transmitted from the periphery base station which forms a periphery cell may be received. The transmission of the first radio signal from the neighboring base station is performed so as to repeatedly transmit the first radio signal including the same cell information a plurality of times. The control unit adjusts radio parameters related to the own cell based on cell information related to the neighboring cells included in the first radio signal. Here, the control unit controls the radio transmission / reception unit to receive the first radio signal including cell information related to the same first cell at least once, and is received by the radio transmission / reception unit. The cell information included in the first radio signal is valid until a predetermined time has elapsed or until a predetermined time.

  A 3rd aspect of this invention is related with the base station apparatus which has a radio | wireless transmission / reception part. The wireless transmission / reception unit is configured to be able to communicate with a mobile station by forming a first cell and to transmit a first wireless signal including cell information regarding the first cell. Here, the cell information is received by a neighboring base station and used for adjusting radio parameters of a cell formed by the neighboring base station. The first radio signal is repeatedly transmitted in units of a plurality of times, and includes cell information having the same content during the one-unit transmission period. Furthermore, the cell information can be updated after the one unit transmission with the same content.

A 4th aspect of this invention is related with the adjustment method of the radio | wireless parameter in a base station. The method includes the following (a) to (c).
(A) receiving at least once a first radio signal including cell information of the same content related to neighboring cells and repeatedly transmitted from the neighboring cells a plurality of times;
(B) validating the cell information included in the received first radio signal until the elapse of a predetermined time or until a predetermined time; and (c) radio parameters relating to the own cell based on the cell information. To adjust.

A fifth aspect of the present invention relates to an information transmission method by a base station that can form a first cell and communicate with a mobile station. The method includes the following (a) to (b).
(A) repeatedly transmitting a first radio signal including cell information of the same content related to the first cell, a plurality of times as a unit, and (b) the cell transmitted by the first radio signal. Update the content of the information on the condition that the transmission of one unit is completed.

A sixth aspect of the present invention relates to a program for causing a computer to execute control related to a base station that forms its own cell and performs wireless communication with a mobile station. The control includes the following (a) to (c).
(A) controlling a radio communication unit included in the base station so as to receive at least once a first radio signal including cell information of the same content related to the neighbor cell and repeatedly transmitted from the neighbor cell a plurality of times;
(B) validating the cell information included in the received first radio signal until a predetermined time elapses or a predetermined time; and (c) radio parameters relating to the own cell based on the cell information. To adjust.

A seventh aspect of the present invention is a program for causing a computer to execute control related to a base station that can form a first cell and communicate with a mobile station. The control includes the following (a) to (b).
(A) repeatedly transmitting a first radio signal including cell information of the same content related to the first cell, a plurality of times as a unit, and (b) the cell transmitted by the first radio signal. Update the content of the information on the condition that the transmission of one unit is completed.

  According to the present invention, when macro cell information used for radio parameter adjustment of a home cell is wirelessly transmitted from a macro base station (M (e) NB in 3GPP), the macro cell information is updated by the macro base station or an upper network. It is possible to provide a mobile communication system, a base station apparatus, a method, and a program that can easily and contribute to the use of updated macro cell information by a plurality of home base stations without causing a large delay.

It is a figure which shows the network structural example of the mobile communication system concerning the 1st Embodiment of this invention. It is a sequence diagram which shows the specific example of the radio | wireless parameter adjustment procedure of the home base station in the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the macro base station in the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the home base station in the 1st Embodiment of invention. It is a flowchart which shows the specific example of the transmission procedure of the macrocell information by the macro base station in the 1st Embodiment of this invention. It is a flowchart which shows the specific example of the radio | wireless parameter adjustment procedure by the home base station in the 1st Embodiment of this invention. It is a figure which shows the downlink radio frame structure of LTE / E-UTRAN. It is a figure which shows the specific example of a MBSFN sub-frame structure. It is a figure which shows the network structural example of the mobile communication system concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the specific example of the radio | wireless parameter adjustment procedure of the home base station in the 2nd Embodiment of this invention. It is a figure which shows the downlink radio frame structure of LTE / E-UTRAN. It is a figure which shows the network structural example of the mobile communication system concerning the 3rd Embodiment of invention. It is a flowchart which shows the specific example of the radio | wireless parameter adjustment procedure by the home base station in the 3rd Embodiment of this invention. It is a figure which shows the specific example of a MBSFN sub-frame structure.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted as necessary for the sake of clarity.

<First Embodiment>
FIG. 1 is a diagram illustrating a network configuration example of the mobile communication system according to the present embodiment. FIG. 1 shows a case where the mobile communication system according to the present embodiment is an EPS (Evolved Packet System). In FIG. 1, only one home base station (HeNB) 1 is shown for simplicity of explanation, but a form in which a plurality of home base stations are arranged in the macro cell 12 is common. In general, there are a plurality of mobile stations 7 connected to the home cell 11 and a plurality of mobile stations 8 connected to the macro cell 12. Hereinafter, the mobile station 7 connected to the home cell 11 is referred to as “HUE (Home UE)”, and the mobile station 8 connected to the macro cell 12 is referred to as “MUE (Macro UE)”.

  The HeNB 1 forms the home cell 11 and performs bidirectional wireless communication with the HUE 7. The HeNB 1 is connected to the upper network 15 via an access line such as an IP (Internet Protocol) network, and relays traffic between the HUE 7 and the upper network 15. In the example of FIG. 1, the upper network 15 includes a core network 150 and a HeNB-GW 151 of a network operator (mobile communication operator). HNB-GW151 is arrange | positioned between the core network 150 and HeNB1, and relays user data and control data between these.

  The MeNB 6 forms a macro cell 12 having a cell size larger than that of the home cell 11 and performs bidirectional wireless communication with the MUE 8. The MeNB 6 is connected to the upper network 15 and relays traffic between the MUE 8 and the upper network 15.

  Furthermore, in the present embodiment, the macro cell information is wirelessly transmitted from the MeNB 6 so that the radio parameters of the home cell 11 can be adjusted according to the radio resource usage status of the macro cell 12, the load status of the macro cell 12, and the like. The HeNB 1 receives the macro cell information and adjusts the radio parameters of the home cell 11 according to the situation of the macro cell 12 indicated by the macro cell information. Hereinafter, details of radio parameter adjustment of the home cell 11 using macro cell information will be described.

  The MeNB 6 periodically transmits a downlink signal including macro cell information. At this time, the MeNB 6 repeatedly transmits a downlink signal including macro cell information having the same content a plurality of times. Specifically, MeNB6 should just transmit the downlink signal containing the macrocell information of the same content in multiple times as 1 unit. For example, when performing transmission in units of five times, the MeNB 6 continuously transmits macro cell information having the same content five times each time a regular transmission timing arrives. That is, when updating the contents of the macro cell information, the MeNB 6 updates the macro cell information at the sixth transmission after the transmission up to the fifth transmission with the same contents is completed, and the updated macro cell at the sixth to tenth transmissions. Send information.

  The macro cell information may include at least one of information on radio resources used in the macro cell 12 and information indicating a load status of the macro cell 12. For example, the macro cell information may include information on radio frequencies or resource blocks used in the macro cell 12. Further, in order to notify the load status of the macro cell 12, the macro cell information includes information on transmission power of the downlink signal by the MeNB 6, information on reception quality of the uplink signal in the MeNB 6, and information on reception quality of the downlink signal in the MUE 8. It is good to include at least one of them. In the case of LTE / E-UTRAN, the reception power level of an uplink reference signal or SIR (Signal to Interference Ratio) may be used as the reception quality of the uplink signal. Here, the uplink reference signal is a demodulation reference signal (DRS) or a sound reference signal (SRS) transmitted from the LTE / E-UTRAN MUE 8. In the case of UTRAN, it is preferable to use the received total wideband power (RTWP) in MeNB 6 as the received quality of the uplink signal.

  The HeNB 1 receives a downlink signal including macro cell information transmitted from the MeNB 6 during operation of the home cell 11. At this time, HeNB1 may stop transmission of the downlink signal with respect to HUE7 temporarily. Here, HeNB1 performs the reception operation | movement of the downlink signal from MeNB6 so that at least 1 can be acquired among the macrocell information of the same content transmitted from MeNB6 in multiple times. HeNB1 should just make macrocell information effective until progress of predetermined time, or predetermined time, after acquiring macrocell information. Here, the predetermined period in which the macro cell information is regarded as valid may be determined based on the total number of transmissions of the MeNB downlink signal including the same macro cell information by the MeNB 6 or the repeated transmission period. HeNB1 should just not perform the reception operation | movement of the downlink signal transmitted from MeNB6, while hold | maintaining effective macrocell information. When the macro cell information becomes invalid due to the elapse of a predetermined time or the arrival of a predetermined time, an operation of receiving a downlink signal from the MeNB 6 may be performed in order to acquire new macro cell information.

The calculation of the predetermined time may be performed according to the following equation (1), for example.
T = (N-n) * T_interval (1)
Here, T is a predetermined time. T_interval is the transmission interval of the MeNB downlink signal including macro cell information. N is the total number of transmissions of the MeNB downlink signal including macro cell information with the same content. n is a transmission order number indicating how many times the macro cell information included in the MeNB downlink signal received by HeNB 1 is the number of times of transmission. The transmission order number may be included in the MeNB downlink signal together with the macro cell information.

  Specifically, HeNB1 should just perform the reception operation | movement of the downlink signal from MeNB6 according to the transmission rule which can determine the frequency | count (total transmission frequency) of macrocell information repeatedly transmitted with the same content, or a repetition transmission period. . For example, in the case of LTE / E-UTRAN, the HeNB1 only needs to be able to specify the number of transmissions or the transmission period with the same content as the resource element to which the physical channel carrying the macrocell information is mapped. Here, the resource element is a minimum allocation unit of LTE / E-UTRAN downlink radio resources employing ODFM (Orthogonal Frequency Division Multiplexing), and is defined by one subcarrier in the frequency domain and one OFDM symbol in the time domain. . The definition of resource elements is described in 3GPP technical specification TS36.211.

  The transmission rule may be stored in advance in a memory (not shown) included in the HeNB 1. Further, at least a part of the transmission rule may be wirelessly transmitted from the MeNB 6. For example, information indicating the total number of transmissions or the repeated transmission period may be included in the MeNB downlink signal together with the macro cell information. In addition, at least a part of the transmission rule is transmitted via an access line from a device (for example, MME (Mobility Management Entity), MCE (Multi-cell / multicast Coordination Entity), management server, etc.) arranged in the upper network 15. You may supply to HeNB1.

  The HeNB 1 refers to the macro cell information, determines the radio resources used in the macro cell 12, the load status of the macro cell 12, and adjusts the radio parameters of the home cell 11. For example, the HeNB 1 may determine radio resources to be used in the home cell 11 so as to avoid radio resources (subcarriers or resource blocks) used in the macro cell 12. Moreover, HeNB1 is good to adjust the downlink transmission power of HeNB1 or the uplink transmission power of HUE7 so that the interference from the home cell 11 to the macrocell 12 may become below a reference level according to the load condition of the macrocell 12.

  Next, a specific example of the radio parameter adjustment procedure of the home cell 11 performed by the HeNB 1 operating the home cell 11 will be described below with reference to the sequence diagram of FIG. In step S101, MeNB6 transmits the downlink signal (henceforth, MeNB downlink signal) containing macrocell information. In step S102, HeNB1 temporarily stops transmission of its own downlink signal (hereinafter referred to as HeNB downlink signal), and receives the MeNB downlink signal. In step S103, HeNB1 acquires macrocell information from the received MeNB downlink signal. In step S104, the HeNB 1 adjusts the radio parameters of the home cell 11 based on the acquired macro cell information.

  In step S105, macro cell information having the same content as in step S101 is retransmitted. Here, the period T_interval is a transmission cycle of macro cell information. For example, if the macro cell information is transmitted once every LTE / E-UTRAN radio frame (10 ms), the period T_interval is 10 ms. In step S106, HeNB1 suspends transmission of a HeNB downlink signal according to the timing at which the MeNB downlink signal containing macrocell information is transmitted. Here, it is assumed that the macro cell information has been successfully acquired in steps S102 and S103. In this case, HeNB1 does not need to receive a MeNB downlink signal in step S106. The reason for stopping the transmission of the MeNB macro cell information even if the macro cell information of the same content has been acquired is that it does not prevent the reception of the MeNB downlink signal by another HeNB 1 arranged in the vicinity.

  Steps S107 and S108 are the same as steps S105 and S106 described above. Although not shown in FIG. 2, after the transmission period of the macro cell information with the same content ends, the HeNB 1 executes the operation of step S102 again.

  As described above, the MeNB 6 repeatedly transmits macro cell information having the same content. HeNB1 performs the reception operation | movement of a MeNB downlink signal so that at least 1 can be acquired among the macrocell information of the same content transmitted in multiple times. Further, after acquiring the macro cell information, the HeNB 1 makes the macro cell information valid until a predetermined time elapses or a predetermined time. Thereby, HeNB1 can determine the timing which should acquire new information according to the elapsed time after acquiring macrocell information previously in consideration of the frequency | count or period when macrocell information of the same content is transmitted. Moreover, MeNB6 can change the transmission content of macrocell information on the condition that transmission of the macrocell information with the same content was completed several times. That is, it is possible to easily update the macro cell information led by the MeNB 6 or the upper network 15. Moreover, HeNB1 can utilize the macrocell information after an update without a big delay because HeNB1 receives at least 1 of the macrocell information transmitted by the same content.

  In the above description, an example in which MeNB 6 generates macro cell information has been shown. However, the arrangement of the macro cell information generation function can be changed as appropriate. For example, the macro cell information generated in the upper network 15 may be supplied to the MeNB 6. For example, in the EPS / E-UTRAN architecture, the MeNB terminates the logical channel, and the MeNB performs macro cell radio resource management. For this reason, it is good also to arrange | position the production | generation function of macrocell information in MeNB. On the other hand, in the UMTS / UTRAN architecture, a radio network controller (RNC) performs radio resource management of macro cells. For this reason, in the UMTS / UTRAN architecture, the RNC may generate macro cell information and supply the macro cell information to the macro base station (MNB).

  Next, configuration examples of the MeNB 6 and the HeNB 1 according to the present embodiment will be described. FIG. 3 is a block diagram illustrating a configuration example of the MeNB 6. In FIG. 3, the radio communication unit 601 performs layer mapping (when MIMO (Multiple Input / Multiple Output) is performed) and precoding (when MIMO is performed) on the transmission symbol sequence supplied from the transmission data processing unit 602. , Mapping to resource elements, OFDM signal generation (IDFT: Inverse Discrete Fourier Transform), frequency conversion, signal amplification, and the like are performed to generate a MeNB downlink signal. The generated MeNB downlink signal is wirelessly transmitted from the antenna. Also, the radio communication unit 601 receives an uplink signal transmitted from the MUE 8 and restores a received symbol sequence.

  The transmission data processing unit 602 acquires user data transmitted toward the MUE 8 from the communication unit 604, and acquires control data (including macro cell information) transmitted toward the HeNB 1 from the macro cell information control unit 605. The transmission data processing unit 602 generates a transport channel by performing error correction coding, rate matching, interleaving, and the like on these transmission data. Further, the transmission data processing unit 602 performs scramble and modulation symbol mapping on the transport channel data sequence to perform physical channel (PBCH (Physical Broadcast Channel), PMCH (Physical Multicast Channel), PDCCH (Physical Downlink Control Channel), PDSCH). (Physical Downlink Shared Channel) etc.) for each transmission symbol string is generated.

  The reception data processing unit 603 restores the reception data for each logical channel from the reception symbol sequence supplied from the wireless communication unit 601. User traffic data and some control data included in the obtained reception data are transferred to the core network 150 via the communication unit 604.

  The macro cell information control unit 605 generates macro cell information and sends it to the transmission data processing unit 102. Note that the macro cell information may be supplied from the upper network to the macro cell information control unit 605. The macro cell information control unit 605 manages repetitive transmission of macro cell information with the same content and update of macro cell information.

  FIG. 4 is a block diagram illustrating a configuration example of the HeNB 1. The wireless communication unit 101 has the same function as the wireless communication unit 601 described above. In addition, the wireless communication unit 101 has a function (Network Listen Mode) for receiving downlink signals from neighboring base stations including the MeNB 6. In the specific configuration of the radio communication unit 101, one radio receiver may be used for both the reception of the uplink signal from the HUE 7 and the reception of the downlink signal from the neighboring base station. Further, the wireless communication unit 101 may include two receivers for receiving an uplink signal from the HUE 7 and receivers for receiving a downlink signal from a neighboring base station.

  The transmission data processing unit 102, the reception data processing unit 103, and the communication unit 104 have the same functions as the transmission data processing unit 602, the reception data processing unit 603, and the communication unit 604 described above. In addition, when the received data processing unit 103 acquires the macro cell information from the received data string of the MeNB downlink signal from the MeNB 6, the received data processing unit 103 sends this to the configuration control unit 105.

  The configuration control unit 105 controls the radio communication unit 101, the transmission data processing unit 102, and the reception data processing unit 103 to temporarily stop HeNB downlink signal transmission and receive a MeNB downlink signal. The configuration control unit 105 adjusts the radio parameter of the home cell 11 according to the macro cell information acquired by the reception data processing unit 103.

  Subsequently, operations of the MeNB 6 and the HeNB 1 will be described with reference to flowcharts. FIG. 5 is a flowchart showing a specific example of the macro cell information transmission operation by the MeNB 6. In step S201, the macro cell information control unit 605 generates macro cell information. In step S202, the value of the counter C for counting the number of times the macro cell information is transmitted is reset to zero. In step S203, it is determined whether the value of the counter C is less than the maximum number of transmissions C_max. When the value of the counter C is less than C_max (YES in step S203), the control unit 605 supplies macro cell information to the transmission data processing unit 602. The transmission data processing unit 602 and the wireless communication unit 601 transmit a downlink signal including macro cell information. In step S205, the value of counter C is incremented by 1, and the process returns to step S203. When the value of the counter C reaches C_max (NO in step S203), the process returns to step S201 to generate new (updated) macro cell information.

  In the example of FIG. 5, the maximum number of transmissions C_max is used to repeatedly transmit macro cell information having the same content. However, the period T_max in which macro cell information having the same content should be transmitted may be specified. T_max may be specified in units of time or may be specified in units of 10 ms radio frames.

  FIG. 6 is a flowchart showing a specific example of the radio parameter adjustment procedure by the HeNB 1. In step S301, HeNB1 suspends transmission of a HeNB downlink signal at the transmission timing of macrocell information, and receives a MeNB downlink signal. In step S302, the configuration control unit 105 determines whether the macro cell information has been successfully acquired. If the macro cell information cannot be acquired (NO in step S302), the HeNB 1 returns to step S301 and attempts to receive the next macro cell information to be transmitted.

  On the other hand, if the macro cell information has been successfully acquired (YES in step S302), the configuration control unit 105 adjusts the radio parameters of the home cell 11 (step S303). Thereafter, until the repeated transmission expires, the HeNB 1 temporarily stops the transmission of the HeNB downlink signal at the transmission timing of the macro cell information (steps S304 and S305). In addition, since it is not necessary to further receive the cell information of the same content as the acquired macro cell information, HeNB1 does not need to perform the reception operation | movement of a MeNB downlink signal.

  In step S303 in FIG. 6, in order to determine the expiration of repeated transmission, the maximum number of transmissions C_max or transmission period T_max of the same content macro cell information in MeNB 6 may be used. These pieces of information may be set in advance in the HeNB 1 or may be supplied from the upper network 15 to the HeNB 1.

  As described above, according to the operation flow of FIG. 6, the HeNB 1 tries to acquire from the head of the macro cell information having the same content. And when acquisition of macrocell information is successful, HeNB1 only performs transmission stop of its own HeNB downlink signal at the transmission timing of subsequent macrocell information with the same content, and does not receive a MeNB downlink signal.

  FIGS. 7A to 7C are diagrams illustrating specific examples of the LTE / E-UTRAN downlink radio frame structure (type 1) in the present embodiment. One radio frame includes ten subframes # 0 to # 9 in the time direction. The length of one radio frame is 10 ms, and the length of one subframe is 1 ms. FIG. 7A shows a downlink signal transmitted from the MeNB 6. A subframe hatched by diagonal lines indicates a subframe used for transmission. Also, the black-filled subframe represents a subframe in which macro cell information is transmitted. In the example of FIG. 7A, a downlink signal including macro cell information is mapped to the fifth subframes 500 to 503 of each radio frame. The number of repeated transmissions is “3”, and the macro cell information transmitted in subframes 500 to 502 has the same content.

  FIG. 7B shows a downlink signal transmitted from the HeNB 1. A subframe hatched by diagonal lines indicates a subframe used for transmission. On the other hand, a white subframe indicates a subframe that is not used for transmission. HeNB1 stops transmission of a HeNB downlink signal in subframes 510 to 513 corresponding to subframes 500 to 503 in which macrocell information is transmitted. Note that the HeNB 1 may perform transmission with low transmission power in the subframes 510 to 513.

  FIG. 7C shows the execution timing of the MeNB downlink signal reception operation by HeNB1. The subframes hatched with diagonal lines indicate the subframes in which HeNB1 performs MeNB downlink signal reception operation. HeNB1 performs the operation of receiving a MeNB downlink signal in subframe 520 corresponding to subframe 500 in which macrocell information is transmitted. If the macro cell information is successfully acquired by this reception operation, the HeNB 1 does not perform the reception operation in the sub frames 521 and 522 corresponding to the sub frames 501 and 502 in which the same macro cell information is transmitted. In the subframe 523 corresponding to the subframe 503 after the repeated transmission is completed, the HeNB1 performs the MeNB downlink signal reception operation again.

  At the end of the present embodiment, a specific example of physical channels that can be used for transmission of macro cell information in LTE / E-UTRAN will be described. LTE / E-UTRAN defines MBSFN (Multimedia Broadcast Multicast Service Single Frequency Network) subframes used for transmitting broadcast information to a plurality of UEs. In addition, in the 3GPP LTE-Advanced Study Item, introduction of a relay station (hereinafter referred to as RN: Relay node) is under consideration. RN is one of the technologies aimed at increasing the communication speed of a mobile station at the cell edge, expanding the cell range of eNB, and the like. The use of MBSFN subframes for data transmission from eNB to RN is under consideration. 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, expanding the cell range of a base station (hereinafter referred to as eNB: Evolved Node B), and the like. Specifically, a new downlink control channel (referred to as R-PDCCH) for transmitting control data from the eNB to the RN and a new downlink shared channel (referred to as R-PDSCH) for transmitting relay data to the RN. Mapping) to MBSFN subframes.

  The above MBSFN subframe may be used for transmission of macro cell information. Specifically, a physical channel for transmitting data (including macro cell information) from MeNB 6 to HeNB 1 may be newly defined and mapped to an MBSFN subframe. FIG. 8 is a diagram illustrating a specific example of the format of the extended MBSFN subframe 800. PDCCH and PDSCH mapped to MBSFN subframe 800 are physical channels for normal MUE8. As described above, R-PDCCH and R-PDSCH are physical channels for RN. H-PDCCH and H-PDSCH are a downlink control channel and a downlink shared channel for HeNB1. The macro cell information may be transmitted using H-PDSCH. The mapping method between H-PDCCH and H-PDSCH is not limited to that shown in FIG.

<Second Embodiment>
In the present embodiment, a modification of the above-described first embodiment will be described. In 1st Embodiment, HeNB1 showed the example which stops transmission of a HeNB downlink signal in the timing at which the macrocell information of the same content as having acquired successfully is transmitted. On the other hand, in this Embodiment, the example which transmits a HeNB downlink signal in the timing at which the macrocell information of the same content as having acquired successfully is transmitted is demonstrated. Thereby, the reduction | decrease in the capacity of the home cell 11 can be suppressed.

  FIG. 9 is a diagram illustrating a network configuration example of the mobile communication system according to the present embodiment. The network configuration of this embodiment may be the same as that of the first embodiment.

  FIG. 10 is a sequence diagram illustrating a radio parameter adjustment procedure of the home cell 11 performed by the HeNB 2 of the present embodiment. Steps S101 to S104 in FIG. 10 are the same as steps S101 to S104 shown in FIG. Here, it is assumed that the macro cell information is successfully acquired in steps S102 and S103.

  In step S105, macro cell information having the same content as in step S101 is retransmitted. In step S406, HeNB2 does not perform the macro cell information reception operation. Furthermore, in step S406, HeNB2 transmits the HeNB downlink signal (HUE data in FIG. 10) with respect to HUE7 using the other radio | wireless resource except the radio | wireless resource (resource element) used for transmission of macrocell information. To do. Steps S107 and S408 are the same as steps S105 and S406 described above.

  FIGS. 11A to 11C are diagrams illustrating specific examples of the LTE / E-UTRAN downlink radio frame structure (type 1) in the present embodiment. In FIG. 11B, at the timing (subframes 711 and 712) at which the macro cell information having the same content as the received macro cell information is transmitted, the HeNB downlink signal is transmitted using resource elements that do not collide with the macro cell information transmission. Is done. This point is in contrast to FIG. 7B described above.

  In 1st Embodiment mentioned above, the example which stops transmission of a HeNB downlink signal was shown in the timing at which the macrocell information of the same content as the received macrocell information is transmitted. In this case, the cell capacity of the home cell 11 may be reduced. This is because the resource elements used for transmitting the macro cell information and its surrounding resource elements cannot be used for downlink transmission from the HeNB 1 to the mobile station. On the other hand, in this Embodiment, transmission of a HeNB downlink signal is continued in the timing at which the macrocell information of the same content as the received macrocell information is transmitted. For this reason, a decrease in the capacity of the home cell 11 can be suppressed. Moreover, since the resource element (namely, subcarrier) used for transmission of macrocell information is not used, reception of the MeNB downlink signal by other HeNB1 arrange | positioned in the periphery is not prevented.

<Third Embodiment>
FIG. 12 is a diagram illustrating a network configuration example of the mobile communication system according to the present embodiment. In the present embodiment, an example in which an update flag is transmitted from MeNB 6 in addition to macro cell information will be described. The update flag indicates whether or not the content has been updated from the macro cell information transmitted in the immediately preceding one unit (multiple times) transmission period. The update flag may be transmitted in combination with the macro cell information and before the macro cell information. In the case of LTE / E-UTRAN, a physical channel including an update flag may be mapped to any resource element transmitted prior to the resource element to which macro cell information is transmitted in each subframe.

  FIG. 13 is a flowchart showing a specific example of the radio parameter adjustment procedure by the HeNB 3 according to the present embodiment. The operations in steps S301 to S305 in FIG. 13 are the same as the steps with the same reference numerals shown in FIG. In step S501, the update flag transmitted before the macro cell information is acquired from the MeNB downlink signal, and the content of the update flag is determined. When the update flag is on, that is, when the macro cell information is updated from the transmission content in the immediately preceding one transmission period (YES in step S501), the HeNB 3 further receives and decodes the MeNB downlink signal, and the macro cell information Is acquired (step S302). On the other hand, when the update flag is off (NO in step S501), the HeNB 1 skips the macro cell information acquisition (step S302). Thereby, HeNB3 can stop the reception of a useless MeNB downlink signal for acquiring the macrocell information which is not updated, or can stop the decoding process of a useless MeNB downlink signal.

  FIG. 14 shows the format of the extended MBSFN subframe 800 shown in FIG. 8 again. For example, the macro cell information may be transmitted using H-PDSCH. At this time, the update flag may be transmitted using H-PDCCH transmitted before H-PDSCH.

  Although the flowchart of FIG. 13 is shown as a modification of the first embodiment, this embodiment may be combined with the second embodiment.

<Fourth embodiment>
In the 1st-3rd embodiment mentioned above, HeNB 1-3 showed the example which tries acquisition from the head among the macrocell information of the same content. However, the HeNBs 1 to 3 may acquire any one of the macro cell information having the same content transmitted a plurality of times, and it is not always necessary to attempt acquisition from the top. For example, the HeNBs 1 to 3 may perform a MeNB downlink signal reception operation in order to obtain arbitrary M-th macro cell information out of macro cell information having the same content repeatedly transmitted N times. Here, N is an integer of 2 or more, and M is an integer of 1 or more and N or less.

<Other embodiments>
In the first to fourth embodiments, the case of EPS / E-UTRAN has been specifically described. However, the home cell radio parameter adjustment method based on the macro cell information described in these embodiments is naturally applicable to other mobile communication systems such as UMTS.

  The processing performed in each of the devices (HeNB1 to 3 and MeNB6) described in the first to fourth embodiments described above is ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), MPU (Micro Processing Unit). Alternatively, it can be realized using a computer system including a CPU (Central Processing Unit) or a combination thereof. Specifically, the computer system may be made to execute a program including a group of instructions related to the processing procedure of each device described with reference to the sequence diagram or the flowchart.

  These programs can be stored in various types of storage media accessible by the computer system. The program can be transmitted via a communication medium. Here, the storage medium includes, for example, a flexible disk, a hard disk, a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD, a ROM cartridge, a battery-backed RAM memory cartridge, a flash memory cartridge, a nonvolatile RAM cartridge, and the like. . In addition, the communication medium includes a wired communication medium such as a telephone line, a wireless communication medium such as a microwave line, and the Internet.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention described above.

1, 2, 3 Home base station (HeNB)
6 Macro base station (MeNB)
7 Mobile station connected to home cell (HUE)
8 Mobile station (MUE) connected to macro cell
11 Home cell 12 Macro cell 15 Host network 101 Wireless communication unit 105 Configuration control unit 150 Core network 151 HeNB-GW
601 Wireless communication unit 605 Macro cell information control unit 500 to 503 Subframe 510 to 513 Subframe 520 to 523 Subframe 711 to 712 Subframe

Claims (44)

A first base station forming a first cell and capable of communicating with a mobile station;
A second base station that forms a second cell and is capable of communicating with a mobile station;
With
The first base station can transmit a first radio signal including the same cell information regarding the first cell a plurality of times,
The second base station receives the first radio signal including the same cell information at least once, and receives the cell information included in the received first radio signal after elapse of a predetermined time or Valid until a predetermined time,
Mobile communication system.   The mobile communication system according to claim 1, wherein the second base station is configured to adjust a radio parameter related to the second cell based on the cell information.   While the second base station holds the valid cell information, the second base station does not receive the first radio signal including the same cell information as the valid cell information. The mobile communication system according to claim 1, wherein a downlink radio signal can be transmitted to a mobile station in a cell.   The mobile communication according to claim 3, wherein the second base station transmits the downlink radio signal using another radio resource different from a radio resource used for transmission of the first radio signal. system.   The said 2nd base station stops the radio | wireless transmission with respect to the mobile station in a said 2nd cell temporarily, when receiving the said 1st radio signal. Mobile communication system.   The said 2nd base station acquires the said cell information intermittently with a period longer than the transmission interval of the said 1st radio signal by the said 1st base station, In any one of Claims 1-5 The mobile communication system described.   The mobile communication system according to any one of claims 1 to 6, wherein the first base station further transmits a second radio signal including information indicating whether or not the content of the cell information is updated. The first base station transmits the first radio signal including the same cell information as a unit a plurality of times, and the content of the cell information can be updated after the unit is transmitted.
The first base station transmits the content of the cell information without transmitting the first radio signal when the content of the cell information to be newly transmitted is the same as that of the immediately preceding transmission of one unit. The mobile communication system according to claim 7, wherein the second radio signal including information indicating that there is no update is transmitted.   The second base station receives the second radio signal, and reads the cell information from the first radio signal on condition that the content of the cell information has been updated. Item 9. The mobile communication system according to Item 7 or 8.   The said 2nd base station acquires the said cell information based on the transmission rule information which can determine the total frequency | count of transmission or repetition transmission period of the said 1st radio signal containing the said same cell information. The mobile communication system according to any one of 1 to 9.   The mobile communication system according to claim 10, wherein at least part of the transmission rule information is supplied to the second base station from an upper network to which the first and second base stations are connected.   The mobile communication system according to claim 10, wherein at least a part of the transmission rule information is wirelessly transmitted from the first base station.   The transmission rule information includes the transmission timing of the first radio signal, the repeated transmission period of the first radio signal including the same cell information, and the first radio signal including the same cell information. The mobile communication system according to any one of claims 10 to 12, comprising at least one of the total number of transmissions.   The first base station transmits the first radio signal including the cell information having the same content a plurality of times according to a predetermined total number of transmissions or a repeated transmission period. The mobile communication system according to item.   The mobile communication system according to claim 14, wherein the first base station repeatedly transmits the first radio signal including the cell information having the same content until reaching a predetermined total number of transmissions.   The mobile communication system according to claim 14, wherein the first base station repeatedly transmits the first radio signal including the cell information having the same content during a predetermined repetitive transmission period.   The mobile communication system according to any one of claims 1 to 16, wherein the first radio signal further includes information on a transmission sequence number indicating how many times the cell information having the same content is transmitted. The predetermined time is T, the transmission interval of the first radio signal is T_interval, the total number of transmissions of the same cell information by the first base station is N, and the second base station receives The said predetermined time T is determined by the following formula | equation, when the transmission order number of the said cell information contained in the said 1st radio signal is set to n, The following formula is any one of Claims 1-17 Mobile communication system.
T = (N-n) * T_interval   The said 2nd base station receives again the said 1st radio signal containing the cell information of the same content as the cell information which failed in reception, when acquisition of the said cell information fails, The mobile communication system according to any one of the above.   20. The cell information according to claim 1, wherein the cell information includes at least one of information on a radio resource used in the first cell and information indicating a load status of the first cell. The mobile communication system described.   The cell information includes at least one of information on transmission power of a downlink signal by the first base station and information on reception quality of an uplink reference signal at the first base station. The mobile communication system according to any one of -20. A base station device that forms its own cell and performs wireless communication with a mobile station,
A wireless transceiver,
Controlling the radio transceiver to receive a first radio signal transmitted from a neighboring base station forming a neighboring cell, and based on cell information regarding the neighboring cell included in the first radio signal, A controller that adjusts radio parameters for its own cell;
With
The transmission of the first radio signal is performed such that the first radio signal including the same cell information is repeatedly transmitted a plurality of times,
The controller is
The wireless transmitter / receiver is controlled to receive at least one first wireless signal including cell information related to the same first cell, and is included in the first wireless signal received by the wireless transmitter / receiver. The cell information is valid until a predetermined time elapses or a predetermined time,
Base station device.   The mobile communication system according to claim 22, wherein the control unit adjusts radio parameters related to the own cell based on the cell information. (Equivalent to Dependent Claim 1 of Amidaka)
The radio transceiver unit does not receive the first radio signal including the same cell information as the valid cell information while the control unit holds the valid cell information. The base station apparatus according to claim 22 or 23, capable of transmitting a downlink radio signal to a mobile station in a cell to itself.   The base station apparatus according to claim 24, wherein the radio transmission / reception unit transmits the downlink radio signal using another radio resource different from a radio resource used for transmitting the first radio signal.   The base according to any one of claims 22 to 25, wherein the radio transmission / reception unit temporarily stops radio transmission to a mobile station in the second cell when receiving the first radio signal. Station equipment.   The base station according to any one of claims 22 to 26, wherein the radio transmission / reception unit intermittently obtains the cell information at a period longer than a transmission interval of the first radio signal by the neighboring base station. apparatus.   The control unit controls the radio transmission / reception unit to further receive a second radio signal including information indicating whether or not the content of the cell information is updated, and the content of the cell information is being updated. The base station apparatus according to any one of claims 22 to 27, wherein the cell information is read from the first radio signal.   The control unit receives the first radio signal by the radio transmission / reception unit based on transmission rule information capable of determining the number of first radio signal total transmissions or the repeated transmission period including the same cell information. The base station apparatus according to any one of claims 22 to 28, wherein:   The transmission rule information includes the transmission timing of the first radio signal, the repeated transmission period of the first radio signal including the same cell information, and the first radio signal including the same cell information. The base station apparatus according to claim 26, comprising at least one of the total number of transmissions. The predetermined time is T, the transmission interval of the first radio signal is T_interval, the total number of transmissions of the same cell information by the first base station is N, and the second base station receives The said predetermined time T is determined by the following formula | equation, when the transmission order number of the said cell information contained in a said 1st radio signal is set to n, The one of Claims 22-30 Base station device.
T = (N-n) * T_interval A radio transceiver configured to form a first cell and communicate with a mobile station and configured to transmit a first radio signal including cell information related to the first cell;
The cell information is received by a neighboring base station and used to adjust radio parameters of a cell formed by the neighboring base station,
The first radio signal is repeatedly transmitted as a unit a plurality of times, and includes cell information having the same content during the transmission period of the unit.
The cell information can be updated after the one unit transmission with the same content.
Base station device.   The base station apparatus according to claim 32, wherein the radio transmission / reception unit further transmits a second radio signal including information indicating presence / absence of content update of the cell information.   When the content of the cell information to be newly transmitted is the same as that of the previous one unit transmission, the wireless transmission / reception unit updates the content of the cell information without transmitting the first wireless signal. The base station apparatus according to claim 33, wherein the second radio signal including information indicating the absence is transmitted.   The wireless transmission / reception unit wirelessly transmits the first information used for determining the total number of transmissions or the repeated transmission period of the first wireless signal including the cell information having the same content. The base station apparatus according to claim 1.   The first information includes a transmission timing of the first radio signal, a repeated transmission period of the first radio signal including the cell information having the same content, and the first radio signal including the cell information having the same content. 36. The base station apparatus according to claim 35, including at least one of the total number of transmissions.   37. The cell information according to any one of claims 32-36, wherein the cell information includes at least one of information on a radio resource used in the first cell and information indicating a load status of the first cell. The base station apparatus as described. (A) receiving at least once a first radio signal including cell information of the same content related to neighboring cells and repeatedly transmitted from the neighboring cells a plurality of times;
(B) validating the cell information included in the received first radio signal until a predetermined time elapses or a predetermined time; and (c) radio parameters relating to the own cell based on the cell information. Adjusting,
A method for adjusting radio parameters in a base station. (D) While holding the effective cell information, the mobile station in the second cell does not receive the first radio signal including the same cell information as the effective cell information. 39. The method of claim 38, further comprising transmitting a downlink radio signal to the.   40. The method of claim 39, wherein the downlink radio signal is transmitted using another radio resource that is different from a radio resource used to transmit the first radio signal.   41. The method according to any one of claims 38 to 40, wherein upon receiving the first radio signal, radio transmission to a mobile station in the own cell is temporarily stopped. An information transmission method by a base station capable of communicating with a mobile station by forming a first cell,
(A) repeatedly transmitting a first radio signal including cell information of the same content related to the first cell, a plurality of times as a unit, and (b) the cell transmitted by the first radio signal. Updating the content of the information on the condition that the transmission of one unit is terminated,
With
The cell information is received by a neighboring base station, and is used for adjusting radio parameters of a cell formed by the neighboring base station. A program for causing a computer to execute control related to a base station that forms its own cell and performs wireless communication with a mobile station,
The control is
(A) controlling a radio communication unit included in the base station so as to receive at least once a first radio signal including cell information of the same content related to the neighbor cell and repeatedly transmitted from the neighbor cell a plurality of times;
(B) validating the cell information included in the received first radio signal until a predetermined time elapses or a predetermined time; and (c) radio parameters relating to the own cell based on the cell information. Adjusting,
A program comprising: A program for causing a computer to execute control related to a base station that can form a first cell and communicate with a mobile station,
The control is
(A) repeatedly transmitting a first radio signal including cell information of the same content related to the first cell, a plurality of times as a unit, and (b) the cell transmitted by the first radio signal. Updating the content of the information on the condition that the transmission of one unit is terminated,
With
The cell information is received by a neighboring base station and used for adjusting radio parameters of a cell formed by the neighboring base station.

Images