JP2007134946A - Random access type radio communications system, base station, mobile station, and radio link establishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communications system which improves the certainty of radio link establishment as a random access type radio communications system, and to provide a base station, a mobile station, and a radio link establishing method. <P>SOLUTION: The mobile station has a transmission section, a transmission power control section, a retransmission interval control section, a receiving section, and a retransmission control section. The transmission section transmits a physical channel of an uplink requesting the base station to establish a radio link to the base station. The transmission power control section determines the transmission power. The retransmission interval control section determines the retransmission interval. The receiving section receives the physical channel signal of a downlink, showing an answer of the base station. The retransmission control section decides whether the physical channel signal of the downlink indicates denial of the request. When the request is denied, the retransmission control section designate retransmission of the physical channel signal of the uplink. The mobile station changes transmission conditions, based on the reception state of the physical channel signal of the downlink, indicating the denial of the received request and retransmits the physical channel signal of the uplink. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a random access wireless communication system, and more particularly, to a radio link establishment method when contention occurs, and a base station apparatus and mobile station apparatus using the establishment method.

  In a wireless communication system, when a communication path is shared by a large number of mobile stations, when a plurality of mobile stations try to use the communication path, contention occurs and communication becomes impossible. Therefore, some rule (protocol) for assigning a communication path to each mobile station is required. In particular, in random access, which is a conflicting protocol, this rule greatly affects the efficient use of communication channels, access time, and the like.

  For example, according to Japanese Patent Laid-Open No. 2000-253097, a technique related to a link establishment procedure in a data communication wireless facility compliant with the domestic weak wireless facility standard is disclosed. The wireless data communication control device confirms that the frequency scheduled to be used is not occupied immediately before the start of transmission at the time of outgoing call, and dynamically sets the retransmission waiting time interval and the data communication unit amount after link establishment according to the number of retransmissions. change. In addition, the wireless data communication control device selects the communication channel based on the corresponding history by holding the previous use channel history in the storage unit according to the radio wave condition of the installation location of the corresponding equipment for the frequency channel to be used. Make it possible.

  Japanese Patent Application Laid-Open No. 2001-251236 discloses a transmission apparatus including a reference signal setting unit and a transmission unit. The reference signal setting means sets a known reference signal to be inserted into the random access channel signal based on the propagation path state or the number of retransmissions of the random access channel signal. The transmission means transmits a random access channel signal into which the set known reference signal and information for requesting the start of communication are inserted.

  Japanese Patent Application Laid-Open No. 2003-23428 discloses a technique related to a multicast transmission station that performs multicast communication with a plurality of multicast reception stations using a common physical channel and a dedicated physical channel. The multicast transmission station includes data transmission means, common poll notification means, selection means, individual poll notification means, and data retransmission means. The data transmission means transmits multicast data to a plurality of multicast receiving stations using a common physical channel. The common poll notification means transmits polled multicast data using a common physical channel in order to receive delivery confirmation notifications from a plurality of multicast receiving stations. The selecting means selects one multicast receiving station that performs the individual poll notification based on the delivery confirmation notification received on the dedicated physical channel. The dedicated poll notification means transmits a poll request message using the dedicated physical channel to the multicast receiving station selected by the selection means. The data retransmission unit retransmits the multicast data using the common physical channel based on the retransmission request received on the dedicated physical channel from the multicast receiving station selected by the selection unit.

  Japanese Patent Laid-Open No. 2003-318804 discloses a technique for maintaining the establishment of a wireless link when a wireless mobile station enters a weak electric field area or an area in which a reception electric field rapidly changes. The mobile communication system includes a radio base station and a radio mobile station that communicates with the radio base station via a radio communication line. The radio mobile station includes retransmission control means for retransmitting the radio control data of the layer 2 or layer 3 of the radio communication protocol according to the degree of deterioration of the downlink communication quality from the radio base station. The radio mobile station performs retransmission processing using the retransmission control parameter only when the communication quality deteriorates.

  Japanese Patent Laid-Open No. 2001-128235 discloses a technique related to a wireless network including at least one base station and a plurality of terminals that exchange user data and control data. The terminal sends a reservation message dependent on a first sustainability to allocate transmission capacity to at least one data packet to the base station. Further transmission information of the reservation request received at least once by the base station depends on at least another sustainability.

  Japanese Patent Laid-Open No. 2003-333661 discloses a technique related to a random access control method in a wireless communication system using a spread spectrum communication system. In this mobile communication system, a mobile station transmits a RACH (Random Access Channel) preamble to notify a base station that a message has occurred prior to transmission of the message when attempting to make a call. When the base station detects the RACH preamble, the base station transmits an AICH (Acquisition Indicator Channel) to the mobile station. The RACH preamble transmission of the mobile station is controlled according to at least the resource usage rate and the state of the receiving line.

  According to Japanese Patent Laid-Open No. 9-200848, a technology related to a slot reservation type ICMA-PE PDC packet mobile communication device is disclosed, which includes a base station and a plurality of mobile stations. The mobile station includes a collision control bit processing unit and a random access control unit. The collision control bit processing unit takes in the downlink signal from the base station and processes the collision control bit. The random access control unit controls random access from the content of the collision control bit. When the mobile station reserves a slot in a lump, the slot can be reserved so that the first unit can be transmitted continuously to a plurality of slots as well as the first slot.

  Japanese Patent Laid-Open No. 9-298493 discloses a transmission apparatus that converts desired transmission data to be transmitted into a high-frequency signal and transmits it. The transmission device includes a pseudo noise generation unit, a timing determination unit, and a data transmission unit. The pseudo noise generating unit generates a pseudo noise code code. The timing determination unit determines the transmission timing of the transmission data in synchronization with the pseudo noise code generated by the pseudo noise generation unit. The data transmission unit performs data transmission a predetermined number of times within a predetermined time based on the timing determined by the timing determination unit.

  Japanese Patent Laid-Open No. 2002-199447 discloses a technique related to a system cordless telephone apparatus including an exchange, a plurality of base stations, and a cordless telephone. The exchange includes retransmission number setting means for setting the number of retransmissions of the incoming call signal, retransmission interval setting means for setting the retransmission interval of the incoming call signal, and retransmission control for controlling retransmission operations of the retransmission interval setting means and the retransmission number setting means. Means. Each of the plurality of base stations is connected to the exchange through a wired line. A cordless telephone is wirelessly connected to a plurality of base stations. In such a system cordless telephone apparatus, the retransmission number setting means sets the number of retransmissions of the incoming call signal for each communication area covered by each of the plurality of base stations.

  Japanese Patent Application Laid-Open No. 2002-335582 discloses a technique related to a communication system that performs connectionless type packet-switched communication using a digital mobile communication network. In this digital mobile communication system, the slot timings of all base stations are synchronized, and all base stations use a common frequency. The mobile station arbitrarily transmits a packet in accordance with the slot timing without establishing a link with a specific base station. The connection between the mobile station and the base station uses a slot Aloha system.

  As described above, in a wireless communication system having a plurality of mobile stations and allowing random access from each mobile station, the mobile station establishes a radio link with the base station in order to transmit a user channel signal from the mobile station. There is a need to. In the following, a wireless communication system that establishes a wireless link of a conventional random access method will be described.

  FIG. 1 shows the configuration of a wireless communication system. The wireless communication system includes a base station 200 and mobile stations 100-1, 100-2, ..., 100-n. The mobile stations 100-1,..., 100-n have the same function, and will be described as the mobile station 100 when any one of the mobile stations is described for ease of explanation. In addition, here, the base station 200 is described as a single station, but may be a system including a plurality of base stations.

  When user channel transmission is required, the mobile station 100 requests the base station 200 to establish a radio link using an uplink transmission request channel. The base station 200 determines whether to allow establishment of a radio link with the mobile station 100 based on the received transmission request channel. When there is no error in the received transmission request channel and there is a user channel to be assigned to the mobile station 100, the base station 200 recognizes the transmission request from the mobile station 100 and sets transmission permission to the transmission permission channel. If there is an error in the received transmission request channel or there is no user channel to be allocated, the base station 200 sets the request rejection to the transmission permission channel.

  The base station 200 notifies the mobile station 100 of transmission permission or rejection of the radio link establishment request using the downlink transmission permission channel. When the transmission is permitted, the mobile station 100 transmits a user channel signal according to an instruction from the base station 200. When the radio link establishment request is rejected, the mobile station 100 requests the radio link establishment again.

  As illustrated in FIG. 2, the mobile station 100 includes a downlink reception unit 901, a transmission permission channel demodulation unit 902, a retransmission control unit 903, an uplink physical channel generation unit 904, a transmission power control unit 905, and an uplink transmission unit 908. Is provided.

  The downlink reception unit 901 receives a downlink physical channel signal transmitted from the base station 200. The received downlink physical channel signal is provided to transmission permission channel demodulation section 902.

  The transmission permission channel demodulation unit 902 receives a downlink physical channel signal and demodulates the transmission permission channel. The demodulated transmission permission channel includes response information of the base station 200 in response to the radio link establishment request. This answer information is sent to the retransmission control unit 903.

  The retransmission control unit 903 determines whether to newly request a radio link establishment or based on the response information, and controls the uplink physical channel generation unit 904 and the transmission power control unit 905. When newly requesting establishment of a radio link, retransmission control section 903 notifies uplink physical channel generation section 904 and transmission power control section 905 that new transmission is to be performed. In the case of a re-request, the retransmission control unit 903 notifies the uplink physical channel generation unit 904 and the transmission power control unit 905 to output a request for establishing a radio link again using the transmission request channel. At this time, the number of retransmissions is also notified. If the response information indicates permission for user channel transmission, since the radio link has been established, the mobile station 100 proceeds to a user channel transmission procedure.

  When notified of uplink new transmission or retransmission, the uplink physical channel generation unit 904 generates and multiplexes a pilot channel and a transmission request channel, and generates an uplink physical channel signal. The generated uplink physical channel signal is sent to the uplink transmitter 908.

  When the number of retransmissions is notified from the retransmission control unit 903, the transmission power control unit 905 obtains the transmission power corresponding to the number of retransmissions. The transmission power is controlled to increase stepwise as the number of uplink physical channel signal retransmissions increases. The obtained transmission power strength is notified to the uplink transmission section 908.

  The uplink transmission unit 908 adjusts the transmission power based on the notified strength of the transmission power, and transmits the uplink physical channel signal supplied from the uplink physical channel generation unit 904 to the base station 200. Here, the interval at which the signal including the transmission request channel is retransmitted is constant.

  Meanwhile, as shown in FIG. 2, the base station 200 includes an uplink receiver 911, a transmission request channel demodulator 912, an uplink received power measurement unit 913, a scheduling unit 914, a downlink physical channel generator 915, a downlink A transmission unit 916 is provided.

  The uplink receiving unit 911 receives an uplink physical channel signal transmitted from the mobile station 100. The received physical channel signal is output to transmission request channel demodulation section 912 and uplink received power measurement section 913.

  The transmission request channel demodulation unit 912 demodulates the uplink physical channel signal. The demodulated transmission request channel includes identification information for identifying the mobile station 100 that has output the transmission request channel. The demodulated transmission request channel is output to scheduling section 914.

  The uplink received power measuring section 913 separates the pilot channel multiplexed on the input uplink physical channel. Uplink received power measurement section 913 measures uplink received power based on this pilot channel. The measured received power strength is output to scheduling section 914.

  The scheduling unit 914 specifies the mobile station 100 that is requesting establishment of a radio link based on the transmission request channel input from the transmission request channel demodulation unit 912. Whether scheduling section 914 permits or rejects establishment of a radio link with mobile station 100 based on the strength of uplink reception power input from uplink reception power measurement section 913 Scheduling is performed. In this scheduling, the scheduling unit 914 gives priority to the mobile station 100 with high uplink reception power and permits establishment of a radio link. This determination result is notified to the downlink physical channel generation unit 915.

  The downlink physical channel generation unit 915 adds the determination result notified from the scheduling unit 914 to the transmission permitted channel. The downlink physical channel generation unit 915 generates a downlink physical channel signal by multiplexing the transmission permission channel to which the determination result is added and the pilot channel. The generated downlink physical channel signal is output to the downlink transmission unit 916.

  The downlink transmission unit 916 transmits the downlink physical channel signal input from the downlink physical channel generation unit 915 to the mobile station 100.

  With reference to FIG. 3, an operation of establishing a radio link in a conventional radio communication system will be described. The radio link establishment is started from the mobile station 100. When user data to be transmitted to the base station 200 is generated, the mobile station 100 transmits an uplink physical channel signal # 0 indicating that a new radio link establishment is requested (step 61).

  The base station 200 receives the physical channel signal # 0 of the radio link establishment request. The base station 200 determines whether to accept or reject the request based on the scheduling algorithm. In the case of the first request shown in FIG. 3, the permitted conditions are not met. The base station 200 adds information indicating rejection to the transmission permission channel, and transmits the downlink physical channel signal # 0 to the mobile station 100 (step 62).

  The mobile station 100 receives the downlink physical channel signal # 0 and recognizes that the request for establishing the radio link has been rejected. The mobile station 100 prepares for retransmission and enters a standby state (step 63).

After the retransmission waiting time t _{int has} elapsed, the mobile station 100 transmits the uplink physical channel signal # 1 that is the first retransmission to the base station 200 (step 64).

  The base station 200 receives the physical channel signal # 1 that is the first retransmission of the mobile station 100. This request does not satisfy the condition again, and the base station 200 adds information indicating rejection to the transmission-permitted channel and transmits the downlink physical channel signal # 1 to the mobile station 100 (step 65).

  The mobile station 100 receives the downlink physical channel signal # 1 and recognizes that the wireless link establishment request for the first retransmission has been rejected. The mobile station 100 prepares for retransmission and enters a standby state (step 66).

The mobile station 100 further transmits an uplink physical channel signal # 2 that is the second retransmission, to the base station 200 after the retransmission waiting time t _{int has} elapsed (step 67).

  The base station 200 receives the second retransmission physical channel signal # 2. The base station 200 confirms that the request at this time satisfies the condition. The base station 200 adds the information indicating that the radio link establishment is valid to the transmission permission channel and transmits the downlink physical channel signal # 2 to the mobile station 100 (step 68).

  The mobile station 100 receives the downlink physical channel signal # 2, and recognizes that information indicating that the radio link is valid is set in the transmission permission channel. Here, a radio link between the mobile station 100 and the base station 200 is established. Thereafter, the mobile station 100 transmits user data to be transmitted using the established radio link (step 69).

At this time, the time until the radio link is established between the mobile station 100 and the base station 200 is 2 × t _int + t _rtt . Here, the round trip time t _rtt between the mobile station 100 and the base station 200 is the downlink physical channel signal corresponding to the uplink physical channel signal after the mobile station 100 transmits the uplink physical channel signal. Indicates the time to receive.

JP 2000-253097 A JP 2001-251236 A Japanese Patent Laid-Open No. 2003-23428 JP 2003-318804 A JP 2001-128235 A JP 2003-333661 A Japanese Patent Laid-Open No. 9-200848 JP-A-9-298493 JP 2002-199447 A JP 2002-335582 A

  As described above, in the radio link establishment method based on the random access scheme, when the retransmission interval of the uplink physical channel signal from each mobile station is constant, it collides with the uplink physical channel signal of another mobile station. there is a possibility. In the case of a collision, an error occurs in the physical channel signal due to interference between the physical channel signals, and the radio link cannot be established.

  In addition, there is a high possibility that a specific mobile station with a good communication state is preferentially established with a radio link, and a radio link with a mobile station with a poor communication state cannot be established. That is, there is a high possibility that all mobile stations cannot establish radio links equally.

  An object of the present invention is to provide a radio communication system, a base station, a mobile station, and a radio link establishment method in which reliability of establishment of a radio link is improved in a random access radio communication system.

  Another object of the present invention is to provide a radio communication system, a base station, a mobile station, and a radio link establishment method capable of establishing radio links equally in all mobile stations.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in [Best Mode for Carrying Out the Invention]. These numbers and symbols are added to clarify the correspondence between the description of [Claims] and [Best Mode for Carrying Out the Invention]. However, these numbers and symbols should not be used for the interpretation of the technical scope of the invention described in [Claims].

  In an aspect of the present invention, a mobile station (100) of a wireless communication system includes a transmission unit (108), a transmission power control unit (106), a retransmission interval control unit (107), a reception unit (101), And a control unit (104). The transmission unit (108) transmits an uplink physical channel signal requesting the base station to establish a radio link to the base station (200). The transmission power control unit (106) determines the transmission power of the uplink physical channel signal. The retransmission interval control unit (107) determines a retransmission interval for setting the transmission timing of the uplink physical channel signal. The receiving unit (101) receives a downlink physical channel signal indicating a response of the base station (200) to the request for establishing a radio link. The retransmission control unit (104) determines whether the downlink physical channel signal indicates rejection of the request. When the downlink physical channel signal indicates rejection of the request, the retransmission control unit (104) instructs retransmission of the uplink physical channel signal. The mobile station (100) changes the transmission condition based on the reception state of the downlink physical channel signal indicating rejection of the received request, and retransmits the uplink physical channel signal.

  In the present invention, the retransmission interval control unit (107) determines the retransmission interval based on the number of retransmissions indicating the number of times the downlink physical channel signal indicating rejection of the request is received. At this time, the retransmission interval control unit (107) shortens the retransmission interval in response to an increase in the number of retransmissions.

  In this invention, a transmission power control part (106) sets the transmission power of an uplink physical channel signal based on the frequency | count of retransmission which shows the frequency | count of having received the downlink physical channel signal which shows rejection of a request | requirement. This transmission power is preferably increased in response to an increase in the number of retransmissions.

  The mobile station (100) of the present invention includes a downlink received power measuring unit (103) that measures received power of a downlink physical channel signal indicating rejection of a request. The mobile station (100) changes the transmission condition based on the measured received power, and retransmits the uplink physical channel signal.

  In the present invention, the retransmission interval control unit (107) determines the retransmission interval based on the measured received power. The transmission power control unit (106) determines the transmission power of the uplink physical channel signal based on the measured reception power.

  In another aspect of the present invention, the base station (200) of the wireless communication system includes a reception unit (201), a determination unit (204), and transmission units (205, 208). The receiving unit (201) receives an uplink physical channel signal requesting establishment of a radio link transmitted from the mobile station (100). The determination unit (204) calculates the priority based on the uplink physical channel signal. The determination unit (204) determines whether to permit or reject the request for establishment of the radio link based on the calculated priority. The transmission units (205, 208) add the determination result to the downlink physical channel signal based on the determination result of the determination unit (204), and transmit the result to the mobile station.

  The determination unit (204) of the present invention calculates the priority based on the number of retransmissions. The number of retransmissions indicates the number of times the mobile station (100) that has received the determination result indicating rejection retransmits an uplink physical channel signal. This priority is preferably proportional to the number of retransmissions.

  In addition, the base station (200) of the present invention includes an uplink received power measurement unit (203). The uplink received power measurement unit (203) measures the uplink received power based on the uplink physical channel signal. The determination unit (204) may calculate the priority based on this uplink received power.

  Further, the determination unit (204) may measure the reception interval of the uplink physical channel signal and calculate the priority based on the reception interval. At that time, the priority is preferably proportional to the ratio between the first reception interval and the nth reception interval. The first reception interval indicates the interval between the reception time point of the new uplink physical channel signal and the reception time point of the first retransmission uplink physical channel signal, and the nth reception interval is the (n−1) th time. The interval between the reception time of the uplink physical channel signal of retransmission and the reception time of the uplink physical channel signal of n-th retransmission is shown.

In the present invention, the determination unit (204) calculates the priority pr _n using pr _n = P _{UL, n} × n × t _{INT, 1} / t _{INT, n} . Here, the number of retransmissions n indicates the number of times that the mobile station (100) that has received the determination result indicating rejection retransmits an uplink physical channel signal. The received power P _{UL, n} indicates the received power of the uplink physical channel signal. The first reception interval t _{INT, 1} indicates the interval between the reception time of the new uplink physical channel signal and the reception time of the uplink physical channel signal for the first retransmission. The n-th reception interval t _{INT, n} indicates an interval between the reception time point of the uplink physical channel signal for the (n-1) th retransmission and the reception time point of the uplink physical channel signal for the n-th retransmission.

  In the present invention, a random access wireless communication system includes a plurality of mobile stations as described above and at least one base station as described above.

  In another aspect of the present invention, a radio link establishment method in a mobile station (100) of a random access radio communication system includes an uplink transmission step, a transmission power control step, a retransmission interval control step, A link receiving step and a retransmission control step. The radio link establishment method is a method for establishing a radio link by changing transmission conditions based on a downlink physical channel signal indicating rejection of a received request and retransmitting an uplink physical channel signal through these steps. It is. The uplink transmission step transmits an uplink physical channel signal that requests the base station (200) to establish a radio link to the base station (200). The transmission power control step determines the transmission power of the uplink physical channel signal. The retransmission interval control step determines a retransmission interval for setting the transmission timing of the uplink physical channel signal. The downlink reception step receives a downlink physical channel signal indicating a response of a base station to a request for establishing a radio link. The retransmission control step determines whether or not the downlink physical channel signal indicates rejection of the request, and instructs retransmission of the uplink physical channel signal when the request indicates rejection of the request.

  In the radio link establishment method of the present invention, the retransmission interval control step determines a retransmission interval based on the number of retransmissions. The number of retransmissions is the number of times the mobile station (100) has received a downlink physical channel signal indicating request rejection. Further, based on the number of retransmissions, the transmission power control step determines the transmission power of the uplink physical channel signal.

  The radio link establishment method of the present invention includes a downlink received power measurement step. The downlink received power measurement step measures the received power of a downlink physical channel signal indicating request rejection. The transmission conditions are changed based on the measured received power, and the uplink physical channel signal is retransmitted.

  As a transmission condition based on the measured reception power, the retransmission interval may be determined in the retransmission interval control step, or the transmission power of the uplink physical channel signal may be determined in the transmission power control step.

  Furthermore, in another aspect of the present invention, a method for establishing a radio link in a base station (200) of a random access radio communication system includes an uplink reception step, a determination step, and a downlink transmission step. The uplink reception step receives an uplink physical channel signal requesting establishment of a radio link transmitted from the mobile station (100). The determination step calculates a priority based on the uplink physical channel signal, and determines whether to permit or reject the establishment of the radio link based on the calculated priority. The downlink transmission step adds the determination result to the downlink physical channel signal based on the determination result of the determination step, and transmits the result to the mobile station (100).

  In the radio link establishment method of the present invention, the determination step calculates the priority based on the number of retransmissions. The number of retransmissions indicates the number of times the mobile station (100) that has received the determination result indicating rejection retransmits an uplink physical channel signal.

  The radio link establishment method of the present invention includes an uplink received power measurement step. The uplink received power measurement step measures the uplink received power based on the uplink physical channel signal. Based on this uplink received power, the determination step calculates the priority. The determination step may measure an uplink physical channel signal reception interval and calculate a priority based on the reception interval.

  According to the present invention, it is possible to provide a radio communication system, a base station, a mobile station, and a radio link establishment method that improve the reliability of radio link establishment.

  Further, according to the present invention, it is possible to provide a radio communication system, a base station, a mobile station, and a radio link establishment method capable of establishing radio links equally in all mobile stations.

  The best mode for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the wireless communication system includes a base station 200 and mobile stations 100-1, 100-2,. In the random access type wireless communication system, when user data to be transmitted from the mobile station 100-i (i = 1,..., N) to the base station 200 is generated, the mobile station 100-i first transmits the base data A radio link for transmitting user data to the station 200 needs to be established. The mobile station 100-i requests the base station 200 to establish a radio link using a signal including an uplink transmission request channel. The base station 200 determines whether to allow establishment of a radio link with the mobile station 100-i based on the received transmission request channel, and determines whether to permit transmission or reject the radio link establishment request in the downlink. The mobile station 100-i is notified using the transmission permission channel. When the transmission is permitted, the mobile station 100-i transmits user data using the user channel according to the instruction. When the radio link establishment request is rejected, the mobile station 100 requests the radio link establishment again.

  As shown in FIG. 4, the mobile station 100 includes a downlink reception unit 101, a transmission permission channel demodulation unit 102, a downlink reception power measurement unit 103, a retransmission control unit 104, an uplink physical channel generation unit 105, a transmission power control. Unit 106, retransmission interval control unit 107, and uplink transmission unit 108.

  The downlink receiving unit 101 receives a downlink physical channel signal transmitted from the base station 200. The received downlink physical channel signal is supplied to the transmission permission channel demodulation unit 102 and the downlink received power measurement unit 103.

  The transmission permission channel demodulator 102 receives a downlink physical channel signal and demodulates the transmission permission channel. The demodulated transmission permission channel includes response information of the base station 200 in response to the radio link establishment request. This answer information is sent to the retransmission control unit 104.

  Downlink received power measurement section 103 extracts multiplexed pilot channels from downlink physical channel signals, and measures downlink received power based on the pilot channels. The downlink received power value is sent to transmission power control section 106 and retransmission interval control section 107.

  The retransmission control unit 104 determines whether to newly request a radio link establishment or a re-request based on the response information, and includes an uplink physical channel generation unit 105, a transmission power control unit 106, and a retransmission interval control unit 107. Control. When newly requesting establishment of a radio link, retransmission control section 104 notifies uplink physical channel generation section 105, transmission power control section 106, and retransmission interval control section 107 that new transmission of radio link establishment is to be performed. . When re-requesting the establishment of the radio link, the retransmission control unit 105 performs retransmission of the uplink physical channel signal to the uplink physical channel generation unit 105, the transmission power control unit 106, and the retransmission interval control unit 107. Notify the number of retransmissions. If the response information indicates permission for user channel transmission, since the radio link has been established, the mobile station 100 proceeds to a user channel transmission procedure.

  The uplink physical channel generation unit 105 newly generates a transmission request channel when notified of new transmission of an uplink physical channel signal. When the retransmission of the uplink physical channel signal is notified, the uplink physical channel generation unit 105 generates the previously transmitted transmission request channel. The uplink physical channel generation unit 105 multiplexes the transmission request channel to which the number of retransmissions is added and the pilot channel, and generates an uplink physical channel signal. This uplink physical channel signal is output to uplink transmitting section 108.

The transmission power control unit 106 transmits the uplink physical channel signal based on the number of retransmissions input from the retransmission control unit 104 and the downlink reception power value input from the downlink reception power measurement unit 103. Determine the power. As shown in FIG. 5, the transmission power control unit 106 includes a transmission power determination table that is referred to when determining the value of the transmission power P _{TX, n} of the uplink physical channel signal. Here, n indicates the number of uplink physical channel signal retransmissions. The number of retransmissions n is from 1 to N times. The received power P _DL is divided into X ranges with P ′ _{DL, x} as the received power threshold. x indicates which of the received power ranges is divided into X pieces. The received power threshold value P ′ _{DL, x} satisfies the following condition.
_{P'DL, 0} <_{P'DL, 1} <_{P'DL, 2} <... <_{P'DL, X-1} <_{P'DL, X}

That is, the first received power range is received power P ′ _{DL, 0 to} P ′ _{DL, 1} , the second received power range is received power P ′ _{DL, 1 to} P ′ _{DL, 2} , and the Xth received power range is , Received power P ′ _{DL, X−1 to} P ′ _{DL, X.} However, when the initial value of the transmission power of the uplink physical channel signal (transmission power of the signal including the first transmission request channel) is P _{TX, 0} , the transmission power P _{TX, nx} in the table is determined by the following condition: Shall be satisfied.
P _{TX, 0} <P _{TX, 10} <P _{TX, 11} <P _{TX, 12} <... <P _{TX, 1X} ,
P _{TX, 20} <P _{TX, 21} <P _{TX, 22} <... <P _{TX, 2X} , ...,
_{PTX, n0} < _{PTX, n1} < _{PTX, n2} <... < _PTX , _nX , ...,
P _{TX, N0} <P _{TX, N1} <P _{TX, N2} <... <P _{TX, NX}

Therefore, when the number of retransmissions is n and the received power P _DL is in the x-th received power range, the transmission power value P _{TX, n} is P _{TX, nx} from the transmission power determination table. This transmission power determination table can be set for each mobile station 100. The determined transmission power value P _{TX, n} is notified to uplink transmission section 108.

The retransmission interval control unit 107 retransmits the uplink physical channel signal based on the number of retransmissions input from the retransmission control unit 104 and the downlink received power value input from the downlink received power measurement unit 103. Determine the transmission interval. As shown in FIG. 6, retransmission interval control section 107 includes a retransmission interval determination table that is referred to when determining the value of retransmission interval t _{INT, n} . Here, n indicates the number of uplink physical channel signal retransmissions. The number of retransmissions n is from 1 to N times. The interval until the first retransmission, that is, the initial value of the retransmission interval is set to _{tINT, 0} . The received power P _DL is divided into X ranges with P ′ _{DL, x} as the received power threshold. x indicates which of the received power ranges is divided into X pieces. The received power threshold value P ′ _{DL, x} satisfies the following condition.
_{P'DL, 0} <_{P'DL, 1} <_{P'DL, 2} <... <_{P'DL, X-1} <_{P'DL, X}

That is, the first received power range is received power P ′ _{DL, 0 to} P ′ _{DL, 1} , the second received power range is received power P ′ _{DL, 1 to} P ′ _{DL, 2} , and the Xth received power range is , Received power P ′ _{DL, X−1 to} P ′ _{DL, X.} Here, it is assumed that it is divided into the same X as the transmission power determination table shown in FIG. 5, but may be different. The retransmission interval t _{INT, nx} is assumed to satisfy the following condition.
t _{INT, 10} <t _{INT, 11} <t _{INT, 12} <... <t _{INT, 1X} ,
t _{INT, 20} <t _{INT, 21} <t _{INT, 22} <... <t _{INT, 2X} , ...,
t _{INT, n0} <t _{INT, n1} <t _{INT, n2} <... <t _{INT, nX,.}
t _{INT, N0} <t _{INT, N1} <t _{INT, N2} <... <t _{INT, NX}

Therefore, when the number of retransmissions n and the measured downlink received power P _DL are in the xth received power range, the retransmission interval t _{INT, n} is t _{INT, nx} from the retransmission interval determination table. This retransmission interval determination table can also be set for each mobile station 100. The retransmission interval t _{INT, n} determined in this way is notified to the uplink transmitter 108.

  The uplink transmission unit 108 waits for the retransmission interval specified by the retransmission interval control unit 107 and then receives the uplink input from the uplink physical channel generation unit 105 with the transmission power specified by the transmission power generation unit 106. The physical channel signal is transmitted to the base station 200.

  The base station 200 includes an uplink reception unit 201, a transmission request channel demodulation unit 202, an uplink reception power measurement unit 203, a scheduling unit 204, a downlink physical channel generation unit 205, and a downlink transmission unit 208.

  The uplink receiving unit 201 receives an uplink physical channel signal transmitted from the mobile station 100. The uplink physical channel signal is supplied to the transmission request channel demodulation unit 202 and the uplink received power measurement unit 203.

  The transmission request channel demodulation unit 202 receives an uplink physical channel signal from the uplink reception unit 201 and demodulates the transmission request channel. The demodulated transmission request channel includes information for identifying a mobile station as a transmission source and mobile station information such as the number of transmissions. This mobile station information is sent to the scheduling unit 204.

Uplink received power measuring section 203 extracts a multiplexed pilot channel from an uplink physical channel signal input from uplink receiving section 201, and uplink received power P _{UL, n} based on the pilot channel. Measure. The uplink received power value is sent to the scheduling section 204.

  Scheduling section 204 receives mobile station information from transmission request channel demodulation section 202 and uplink received power value from uplink received power measurement section 203. The mobile station information includes information for identifying the mobile station 100 that has issued a request for establishing a radio link, and the number of retransmissions of a signal including a transmission request channel. The scheduling unit 204 identifies the mobile station 100 and retransmits the signal. Detect the number of transmissions. In addition, the scheduling unit 204 measures the reception interval ratio of the signal including the retransmitted transmission request channel for each mobile station. Based on the reception interval ratio of the signal including the transmission request channel, the number of retransmissions, and the received power value of the uplink, the scheduling unit 204 permits the radio link establishment between the mobile station 100 and the base station 200. Is valid or invalid. The scheduling unit 204 prioritizes the radio link establishment permission with priority given to the mobile station 100 having a large number of retransmissions. The determination result is notified to the downlink physical channel generation unit 205.

Here, details of this determination will be described. First, it is confirmed that there is no error in the demodulation result of the transmission request channel. If there is an error, permission to establish a radio link is invalidated before making the following determination. Scheduling preferentially assigns the mobile station 100 having the highest priority coefficient pr _n to the uplink user channel among the mobile stations 100 requesting establishment of the radio link. When the number of retransmissions is n, the uplink reception power is P _{UL, n} , and the uplink reception interval is t _{INT, n} , the priority coefficient pr _n is calculated by the following equation.

pr _n = P _{UL, n} × n × t _{INT, 1} / t _{INT, n} (1)
However, in the case of transmission of a new uplink physical channel signal from the mobile station 100, t _{INT, n} = t _{INT, 1, that} is, pr _n = P _{UL, n} . Note that t _{INT, 1} / t _{INT, n} is the ratio between the first retransmission interval and the current (n-th) retransmission interval, that is, the reception interval ratio of the retransmitted transmission request channel. The priority coefficient pr _n increases as the uplink reception power increases, the number of retransmissions increases, and the reception interval of the transmission request channel decreases. Therefore, it can be seen that the mobile station 100 that has repeated retransmissions is easily prioritized.

  The downlink physical channel generation unit 205 is notified of the radio link establishment permission validity / invalidity determination result from the scheduling unit 204, and adds the determination result to the transmission permission channel. The downlink physical channel generation unit 205 multiplexes the transmission permission channel and the pilot channel to generate a downlink physical channel signal. The generated downlink physical channel signal is supplied to the downlink transmission unit 208.

  The downlink transmission unit 208 transmits the downlink physical channel signal supplied from the downlink physical channel generation unit 205 to the mobile station 100.

  Next, an operation for establishing a radio link in the random access scheme between the mobile station 100 and the base station 200 will be described with reference to the drawings.

  With reference to FIG. 7, the operation of mobile station 100 when establishing a radio link with base station 200 will be described.

For example, when user data to be transmitted to the base station 200 is generated, the mobile station 100 starts establishing a new radio link. First, as a preparation for uplink transmission, the retransmission control unit 104 notifies the uplink physical channel generation unit 105, the transmission power control unit 106, and the retransmission interval control unit 107 that a new radio link establishment is started, Prompt for initial setting. At this time, the retransmission control unit 104 notifies the number of retransmissions n (= 0). The transmission power control unit 106 sets the initial transmission power value P _{TX, 0} as the transmission power value of the uplink physical channel signal based on the number of retransmissions n = 0. The initial transmission power value P _{TX, 0} is preferably held in the transmission power control unit 106 and set for each mobile station 100. The retransmission interval control unit 107 sets the retransmission interval initial value t _{INT, 0} as the retransmission interval t _{INT, n} based on the number of retransmissions n = 0. This retransmission interval initial value t _{INT, 0} is preferably held in retransmission interval control section 107 and set for each mobile station 100. The transmission power value determined by the transmission power control unit 106 and the retransmission interval determined by the retransmission interval control unit 107 are notified to the uplink transmission unit 108 (step S10).

  The uplink physical channel generation unit 105 multiplexes the transmission request channel and the pilot channel, and generates an uplink physical channel signal. The number of retransmissions n (= 0) given from the retransmission control unit 104 and information for identifying the mobile station 100 are added to this transmission request channel. The uplink physical channel generation unit 105 outputs an uplink physical channel signal to the uplink transmission unit 108. Based on the transmission power value determined by the transmission power control unit 106 and the retransmission interval determined by the retransmission interval control unit 107, the uplink transmission unit 108 generates the uplink transmission generated by the uplink physical channel generation unit 105. A physical channel signal is transmitted to the base station 200 (step S12).

When the mobile station 100 transmits an uplink physical channel signal, the mobile station 100 waits for a downlink reception from the base station 200. The base station 200 processes the transmission request from the mobile station 100 and notifies the result on the downlink. The downlink reception unit 101 of the mobile station 100 receives the downlink physical channel signal transmitted from the base station 200 and supplies the downlink physical channel signal to the transmission permission channel demodulation unit 102 and the downlink received power measurement unit 103. The transmission permission channel demodulation unit 102 demodulates the transmission permission channel from the downlink physical channel signal, and outputs response information of the base station 200 to the radio link establishment request to the retransmission control unit 104. Downlink received power measurement section 103 extracts a multiplexed pilot channel from the downlink physical channel signal _, and measures downlink received power P _{DL, n} based on the pilot channel. The received power value is output to transmission power control section 106 and retransmission interval control section 107 (step S14).

  Based on the answer information, retransmission control section 105 determines whether or not uplink user channel transmission is permitted (step S16). If transmission is permitted (step S16—permitted), uplink user channel transmission is started, and the process of establishing a radio link between the mobile station 100 and the base station 200 is completed. In the case of rejection (step S16—rejection), the radio link cannot be established between the mobile station 100 and the base station 200. Therefore, the mobile station 100 moves to the procedure of uplink physical channel retransmission.

The number of retransmissions n is incremented. That is, when a new wireless link establishment request is rejected, the number of retransmissions n is 1. The transmission power control unit 106 refers to the transmission power determination table (FIG. 5) based on the number of retransmissions n and the downlink reception power P _{DL, n,} and retransmits the radio link establishment request. The transmission power _{PTX, n} of the physical channel signal is determined. The retransmission interval control unit 107 refers to the retransmission interval determination table (FIG. 6) based on the number of retransmissions n and the downlink received power P _{DL, n,} and performs uplink physical retransmission. The transmission interval t _{INT, n} of the channel signal is determined. That is, the next radio link establishment request is transmitted after the transmission interval t _{INT, n} from the time when the rejected radio link establishment request is transmitted (step S18). Returning to step S12, the uplink physical channel signal is retransmitted based on the determined transmission power _{PTX, n} and transmission interval _{tINT, n} . The mobile station 100 repeats step S12 to step S18 until the radio link establishment is completed.

  Next, the operation of the base station 200 when there is a radio link establishment request from the mobile station 100 will be described with reference to FIG.

In the base station 200, the uplink receiving unit 201 receives the uplink physical channel signal transmitted from the mobile station 100 and supplies it to the transmission request channel demodulating unit 202 and the uplink received power measuring unit 203. Uplink received power measurement section 203 extracts the multiplexed pilot channel from the uplink physical channel signal and measures _uplink received power P _{UL, n} based on the pilot channel. The transmission request channel demodulation unit 202 demodulates the transmission request channel multiplexed on the uplink physical channel signal and extracts mobile station information. Uplink received power P _{UL, n} and mobile station information are output to scheduling section 204 (step S20).

The scheduling unit 204 determines whether or not the transmission permission request of the mobile station 100 can be made based on the demodulation result of the transmission request channel and reception power. First, the scheduling unit 204 checks whether there is an error in the demodulation result of the transmission request channel. If there is an error in the demodulation result, the transmission permission request of the mobile station 100 is rejected. It is determined whether or not the mobile station 100 can request transmission permission without error in the demodulation result. The scheduling unit 204 calculates a priority coefficient pr _n for each mobile station 100. As described above, the priority coefficient Pr _n is calculated as pr _n = P _{UL, n} × n × t _{INT, 1} / t _{INT, n} . The mobile station 100-m having the highest calculated priority coefficient pr _n is assigned an uplink user channel. That is, the transmission permission request of the mobile station 100-m is permitted, and the other mobile station 100 is denied the transmission permission request (step S22).

  The result of determining whether or not the transmission permission request from the mobile station 100 is acceptable is transmitted to the mobile station 100. The downlink physical channel generation unit 205 adds the transmission permission request determination result determined by the scheduling unit 204 to the transmission permission channel. The downlink physical channel generation unit 205 multiplexes the transmission permission channel and the pilot channel to generate a downlink physical channel signal. The generated downlink physical channel signal is transmitted to the mobile station 100 by the downlink transmission unit 208 (step S24). The base station 200 repeats this every time it receives a transmission permission request from the mobile station 100. If there is no downlink user channel to be assigned to the mobile station 100 (when there is no resource), all transmission permission requests are rejected regardless of the result of the determination.

  Next, the operation timing between the mobile station 100 and the base station 200 will be described. FIG. 9 shows operation timings of the mobile station 100 and the base station 200 that have established a radio link at the second retransmission.

  When user data to be transmitted to the base station 200 is generated, the mobile station 100 transmits an uplink physical channel signal # 0 indicating that a new radio link establishment is requested (step 71).

The base station 200 receives the physical channel signal # 0 of the radio link establishment request. The base station 200 determines whether to permit or reject this request. This new radio link establishment request is rejected because an error has been detected or the conditions permitted by the low priority coefficient pr _n are not met. The base station 200 adds information indicating rejection to the transmission permission channel, and transmits the downlink physical channel signal # 0 to the mobile station 100 (step 72).

The mobile station 100 receives the downlink physical channel signal # 0 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100 prepares for retransmission and enters a standby state (step 73). At this time, retransmission interval t _{INT, 1} and transmission power P _{TX, 1} are calculated based on the number of retransmissions n = 1 and received power P _{DL, 0} , and are set in uplink transmission section 108.

The mobile station 100 transmits the uplink physical channel signal # 1, which is the first retransmission, to the base station 200 with the transmission power P _{TX, 1} after the retransmission standby time t _{INT, 1 has} elapsed (step 74).

The base station 200 receives the physical channel signal # 1 that is the first retransmission of the mobile station 100. The received power P _{UL, 1} increases, the number of retransmissions n becomes “1”, and the priority coefficient pr ₁ increases, but this request also does not satisfy the condition. Accordingly, the base station 200 adds information indicating rejection to the transmission-permitted channel and transmits the downlink physical channel signal # 1 to the mobile station # 1 (step 75).

The mobile station 100 receives the downlink physical channel signal # 1 and recognizes that the wireless link establishment request for the first retransmission has been rejected. The mobile station 100 prepares for the second retransmission. Based on the number of retransmissions n = 2 and the received power P _{DL, 1} of the downlink physical channel signal # 1, the retransmission interval t _{INT, 2} and the transmission power P _{TX, 2} are calculated and set in the uplink transmitter 108. (Step 76).

Mobile station 100 may retransmit wait time _{t INT, 2} after, the second uplink physical channel signal # 2 is retransmitted to the base station 200 at transmit power _{P TX, 2} (step 77).

The base station 200 receives the physical channel signal # 2 that is the second retransmission of the mobile station 100. Further increase reception power P _{UL, 2,} number of retransmissions n becomes "2", since the retransmission interval ratio also increases, priority coefficient pr ₂ is further increased. Therefore, the wireless link establishment request is permitted by this second retransmission. The base station 200 adds information indicating that the radio link establishment is valid to the transmission permission channel, and transmits the downlink physical channel signal # 2 to the mobile station 100 (step 78).

  The mobile station 100 receives the downlink physical channel signal # 2, and recognizes that information indicating that the radio link is valid is set in the transmission permission channel. Here, a radio link between the mobile station 100 and the base station 200 is established. Thereafter, the mobile station 100 transmits user data to be transmitted using the established radio link (step 79).

At this time, the time until the wireless link is established between the mobile station 100 and the base station 200 is t _{INT, 1} + t _{INT, 2} + t _rtt . Here, the round trip time t _rtt between the mobile station 100 and the base station 200 is the downlink physical channel signal corresponding to the uplink physical channel signal after the mobile station 100 transmits the uplink physical channel signal. Indicates the time to receive. The relationship between the conventional retransmission interval t _int and the retransmission interval t _{INT, 1} , t _{INT, 2} , t _{INT, 3} of the present embodiment,
Let t _int = t _{INT, 1} > t _{INT, 2} > t _{INT, 3} . In the case of the same retransmission number 2, compared with the time until the conventional wireless link is established,
2 × t _int + t _rtt > t _{INT, 1} + t _{INT, 2} + t _rtt
Thus, it can be seen that the time until the wireless link establishment in this embodiment is short. For this reason, the number of transmissions of a transmission permission request within a certain time increases, and the possibility that the request is permitted increases.

  Furthermore, the operation timing between the two mobile stations 100-1 and 100-2 and the base station 200 will be described with reference to FIG. Here, retransmission of the first transmission permission request of mobile station 100-1 and transmission of a new transmission permission request of mobile station 100-2 are performed substantially simultaneously.

  When user data to be transmitted to the base station 200 is generated, the mobile station 100-1 transmits an uplink physical channel signal # 0 indicating that a new radio link establishment is requested (step 81).

The base station 200 receives the physical channel signal # 0 of the radio link establishment request and determines whether the request is permitted / rejected. This new radio link establishment request is rejected because an error has been detected or the conditions permitted by the low priority coefficient pr _n are not met. The base station 200 adds information indicating rejection to the transmission permission channel, and transmits the downlink physical channel signal # 0 to the mobile station 100-1 (step 82).

  The mobile station 100-1 receives the downlink physical channel signal # 0 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100-1 prepares for retransmission and enters a standby state (step 83).

The mobile station 100-1 transmits the uplink physical channel signal # 1, which is the first retransmission, to the base station 200 with the transmission power P _{TX, 1} after the retransmission waiting time t _{INT, 1 has} elapsed (step 84). . At this time, the mobile station 100-2 transmits user equipment data to be transmitted to the base station 200 and transmits an uplink physical channel signal # 0 indicating that a new radio link establishment is requested (step 81 ′). . These uplink transmissions are almost simultaneous and are prone to error due to interference with each other. Accordingly, the base station 200 invalidates the transmission permission, and transmits the downlink physical channel signal # 1 to the mobile station 100-1 and the downlink physical channel signal # 0 to the mobile station 100-2 (Step S1). 85, 82 ').

  The mobile station 100-1 receives the downlink physical channel signal # 1 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100-1 prepares for retransmission and enters a standby state (step 86). On the other hand, the mobile station 100-2 receives the downlink physical channel signal # 0 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100-2 prepares for retransmission and enters a standby state (step 83 ').

Mobile station 100-1, retransmission wait time _{t INT, 2} after, the second uplink physical channel signal # 2 is retransmitted to the base station 200 at transmit power _{P TX, 2} (Step 87) . The mobile station 100-2 transmits the uplink physical channel signal # 1 that is the first retransmission after the elapse of the retransmission waiting time t _{INT, 1} after the retransmission of the mobile station 100-1 to the transmission power P _{TX, 1} is transmitted to the base station 200 (step 84 ').

  The base station 200 determines that the condition is not satisfied for these transmission permission requests. Accordingly, the base station 200 invalidates the transmission permission, and transmits the downlink physical channel signal # 2 to the mobile station 100-1 and the downlink physical channel signal # 1 to the mobile station 100-2 (Step S1). 88, 85 ').

  The mobile station 100-1 receives the downlink physical channel signal # 2 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100-1 prepares for retransmission and enters a standby state (step 89). On the other hand, the mobile station 100-2 receives the downlink physical channel signal # 1 and recognizes that the request for establishing the radio link has been rejected. The retransmission control unit 104 of the mobile station 100-2 prepares for retransmission and enters a standby state (step 86 ').

The mobile station 100-1 transmits the uplink physical channel signal # 3, which is the third retransmission, to the base station 200 with the transmission power P _{TX, 3} after the retransmission waiting time t _{INT, 3 has} elapsed (step 90). . The base station 200 receives the uplink physical channel signal # 3. Without competition with the mobile station 100-2, also, since by such that the number of retransmissions is 3 priority coefficient pr ₃ is higher, the base station 200 permits a radio link establishment request. The base station 200 adds information indicating that the radio link establishment is valid to the transmission permission channel and transmits the downlink physical channel signal # 3 to the mobile station 100-1 (step 91). The mobile station 100-1 receives the downlink physical channel signal # 3 and recognizes that transmission permission has been obtained (step 92). Here, the radio link between the mobile station 100-1 and the base station 200 is established.

On the other hand, the mobile station 100-2 further transmits the uplink physical channel signal # 2 that is the second retransmission after the retransmission waiting time _{tINT, 2} after a further delay from the retransmission of the mobile station 100-1. _{PTX, 2} is transmitted to the base station 200 (step 87 '). The base station 200 receives the uplink physical channel signal # 2. At this time, since the mobile station 100-1 has already established a radio link and the radio link establishment request of the mobile station 100-2 also satisfies the conditions, the base station 200 permits the radio link establishment request. give. The base station 200 adds information indicating that the radio link establishment is valid to the transmission permission channel and transmits the downlink physical channel signal # 2 to the mobile station 100-2 (Step 94). The mobile station 100-2 receives the downlink physical channel signal # 2 and recognizes that transmission permission has been obtained (step 95). Here, a radio link between the mobile station 100-2 and the base station 200 is established.

In this way, since the number of retransmissions n between the mobile station 100-1 and the mobile station 100-2 is different, the retransmission interval _{tINT, n} between the mobile station 100-1 and the mobile station 100-2 is different, and the number of retransmissions The transmission timing deviates with each increase. Therefore, the transmission timing of the uplink physical channel signal between the mobile stations can avoid collision.

In the present embodiment, the unit of time between the base station round-trip time _trtt and the retransmission interval _tINT , _n is not particularly limited, and may be a second unit, and may be any symbol time, chip time, etc. Units.

Further, the downlink received power P _{DL, n that} is a base for calculating the transmission power P _{TX, n} has been described using the instantaneous value _, but the downlink received power P _{DL, n} after the retransmission is used _{. It} is good also as an average value of ₀ , _{PDL, 1} , ..., _{PDL, n} . Further, the downlink received power P _{DL, n that} is a base for calculating the retransmission interval t _{INT, n} has been described using an instantaneous value. However, the downlink received power P _DL after the retransmission has been described. _{, 0} , P _{DL, 1} ,..., P _{DL, n} may be an average value.

  As described above, when a radio link is established using a random access scheme, according to the present invention, each mobile station can perform uplink transmission according to the number of uplink physical channel signal retransmissions and downlink received power. Control the retransmission interval of physical channel signals. Therefore, it is possible to reduce the number of times the uplink physical channel signal transmitted from each mobile station collides. Accordingly, it is possible to reduce errors in the uplink physical channel signal when the radio link is established.

  Each mobile station controls the retransmission interval of the uplink physical channel signal according to the number of retransmissions and the downlink received power. Therefore, an opportunity to transmit an uplink physical channel signal for establishing a radio link is controlled. Also, the transmission power of the uplink physical channel signal is controlled in accordance with the number of retransmissions and the downlink reception power. Therefore, it is possible to reduce the occurrence of errors in uplink physical channel signals. Therefore, by the transmission control of the uplink physical channel signal of the mobile station, it is possible to establish a radio link equally between a mobile station with good communication status and a mobile station with poor communication status.

  Further, in scheduling at the base station, a priority coefficient is calculated based on the number of retransmissions, the retransmission interval, and the uplink received power, and the transmission permission of the uplink user channel is enabled by the priority coefficient. A mobile station is selected. Therefore, a wireless link can be established without depending on the communication state. Therefore, a mobile station with a good communication state and a mobile station with a bad communication state can establish a radio link equally.

It is a block diagram which shows the structure of a radio | wireless communications system. It is a block diagram which shows the structure of the conventional mobile station and base station. It is a figure which shows operation | movement with the mobile station at the time of the conventional radio link establishment, and a base station. It is a block diagram which shows the structure of the mobile station and base station which concern on embodiment of this invention. It is a figure which shows the structure of the transmission power determination table. It is a figure which shows the structure of the same retransmission interval determination table. It is a flowchart which shows operation | movement of the mobile station. It is a flowchart which shows operation | movement of the base station. It is a figure which shows the operation timing of the mobile station and a base station. It is a figure which shows the operation | movement timing of the said 2 mobile station and a base station.

Explanation of symbols

100, 100-1, 100-2,..., 100-n mobile station 101 downlink receiving unit 102 transmission permission channel demodulating unit 103 downlink received power measuring unit 104 retransmission control unit 105 uplink physical channel generating unit 106 transmission power control Unit 107 retransmission interval control unit 108 uplink transmission unit 200 base station 201 uplink reception unit 202 transmission request channel demodulation unit 203 uplink received power measurement unit 204 scheduling unit 205 downlink physical channel generation unit 208 downlink transmission unit 901 downlink Reception unit 902 Transmission permission channel demodulation unit 903 Retransmission control unit 904 Uplink physical channel generation unit 905 Transmission power control unit 908 Uplink transmission unit 911 Uplink reception unit 912 Transmission request channel demodulation unit 913 Uplink Received power measurement unit 914 Scheduling unit 915 Downlink physical channel generation unit 916 Downlink transmission unit

Claims (26)

A transmitter for transmitting to the base station an uplink physical channel signal requesting the base station to establish a radio link;
A transmission power control unit for determining transmission power of the uplink physical channel signal;
A retransmission interval control unit for determining a retransmission interval for setting transmission timing of the uplink physical channel signal;
A receiver for receiving a downlink physical channel signal indicating a response of the base station to the request for establishment of the radio link;
A retransmission control unit that determines whether or not the downlink physical channel signal indicates rejection of the request, and instructing retransmission of the uplink physical channel signal when indicating the rejection of the request; and
A mobile station that changes a transmission condition based on a reception state of the downlink physical channel signal indicating rejection of the received request and retransmits the uplink physical channel signal. The mobile station according to claim 1, wherein the retransmission interval control unit determines the retransmission interval based on a number of retransmissions indicating the number of times the downlink physical channel signal indicating rejection of the request is received. The mobile station according to claim 2, wherein the retransmission interval control unit shortens the retransmission interval in response to an increase in the number of retransmissions. The transmission power control unit sets transmission power of the uplink physical channel signal based on the number of retransmissions indicating the number of times the downlink physical channel signal indicating rejection of the request is received. The mobile station according to claim 3. The mobile station according to claim 4, wherein the transmission power control unit increases the transmission power in response to an increase in the number of retransmissions. A downlink received power measurement unit that measures received power of the downlink physical channel signal indicating rejection of the request;
The mobile station according to any one of claims 1 to 5, wherein the retransmission control unit instructs retransmission of the uplink physical channel signal in which the transmission condition is changed based on the received power. The mobile station according to claim 6, wherein the retransmission interval control unit determines the retransmission interval based on the received power. The mobile station according to claim 6 or 7, wherein the transmission power control unit determines transmission power of the uplink physical channel signal based on the received power. A receiver that receives an uplink physical channel signal requesting establishment of a radio link transmitted from a mobile station;
A determination unit that calculates priority based on the uplink physical channel signal, and determines whether to permit or reject the request for establishment of the radio link based on the calculated priority;
A base station comprising: a transmission unit that adds the determination result to a downlink physical channel signal based on the determination result of the determination unit and transmits the result to the mobile station. The said determination part calculates the said priority based on the frequency | count of retransmission which shows the frequency | count that the said mobile station which received the said determination result which shows the said rejection retransmits the said physical channel signal of an uplink. Base station. The base station according to claim 10, wherein the determination unit calculates the priority so as to be proportional to the number of retransmissions. An uplink received power measuring unit for measuring uplink received power based on the uplink physical channel signal;
The base station according to claim 9, wherein the determination unit calculates a priority based on the uplink received power. The determination unit measures a reception interval of the uplink physical channel signal,
The base station according to any one of claims 9 to 12, wherein the priority is calculated based on the reception interval. The determination unit sets the priority to a first reception interval indicating an interval between a reception time of the new uplink physical channel signal and a reception time of the uplink physical channel signal of the first retransmission,
Proportional to the ratio of the reception time of the uplink physical channel signal at the (n-1) th retransmission and the nth reception interval indicating the interval between the reception time of the uplink physical channel signal at the nth retransmission. The base station according to claim 13, wherein the base station is calculated as follows. The number of retransmissions indicating the number of times the mobile station that has received the determination result indicating the rejection retransmits the uplink physical channel signal is n,
The received power of the uplink physical channel signal is P _{UL, n} ,
The first reception interval indicating the interval between the reception time of the new uplink physical channel signal and the reception time of the uplink physical channel signal in the first retransmission is t _{INT, 1} ,
The nth reception interval indicating the interval between the reception time point of the uplink physical channel signal in the (n-1) th retransmission and the reception time point of the uplink physical channel signal in the nth retransmission is _{tINT, n.} ,
If the priority is pr _n ,
The determination _{unit, pr n = P UL, n} × n × t INT, 1 / t INT, the base station according to claim 13 or claim 14 calculates the priority by _n. A plurality of mobile stations according to any one of claims 1 to 8,
A wireless communication system comprising: at least one base station according to any one of claims 9 to 15. A wireless link establishment method in a mobile station of a random access wireless communication system,
An uplink transmission step of transmitting to the base station an uplink physical channel signal requesting the base station to establish a radio link;
A transmission power control step for determining transmission power of the uplink physical channel signal;
A retransmission interval control step for determining a retransmission interval for setting a transmission timing of the uplink physical channel signal;
A downlink receiving step of receiving a downlink physical channel signal indicating a response of the base station to the request for establishment of the radio link;
A retransmission control step for determining whether the downlink physical channel signal indicates rejection of the request, and instructing retransmission of the uplink physical channel signal when indicating the rejection of the request; and
A radio link establishment method, wherein a transmission condition is changed based on a reception state of the downlink physical channel signal indicating rejection of the received request, and the uplink physical channel signal is retransmitted. The radio link establishment method according to claim 17, wherein the retransmission interval control step determines the retransmission interval based on the number of retransmissions indicating the number of times the downlink physical channel signal indicating rejection of the request is received. The transmission power control step determines transmission power of the uplink physical channel signal based on the number of retransmissions indicating the number of times the downlink physical channel signal indicating rejection of the request is received. The radio link establishment method according to claim 18. A downlink received power measurement step of measuring received power of the downlink physical channel signal indicating rejection of the request;
The radio link establishment method according to any one of claims 17 to 19, wherein the retransmission control step instructs retransmission of the uplink physical channel signal whose transmission condition is changed based on the received power. The radio link establishment method according to claim 20, wherein the retransmission interval control step determines the retransmission interval based on the received power. The mobile station according to claim 20 or 21, wherein the transmission power control step determines transmission power of the uplink physical channel signal based on the received power. A wireless link establishment method in a base station of a random access wireless communication system,
An uplink reception step of receiving an uplink physical channel signal requesting establishment of a radio link transmitted from a mobile station;
A determination step of calculating a priority based on the uplink physical channel signal and determining whether to allow or reject the establishment of the radio link based on the calculated priority;
A downlink transmission step comprising: a downlink transmission step of adding the determination result to a downlink physical channel signal based on the determination result of the determination step and transmitting the result to the mobile station. The priority level is calculated based on the number of retransmissions indicating the number of times the mobile station that has received the determination result indicating the rejection retransmits the uplink physical channel signal. Wireless link establishment method. An uplink received power measurement step for measuring uplink received power based on the uplink physical channel signal;
The radio link establishment method according to claim 23 or 24, wherein the determination step calculates a priority based on the uplink received power. The determining step measures a reception interval of the uplink physical channel signal,
The radio link establishment method according to any one of claims 23 to 25, wherein the priority is calculated based on the reception interval.

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