JP5832811B2 - Radio base station and radio communication system - Google Patents

Description

  The present invention relates to a radio base station and a radio communication system.

  As a wireless communication system, LTE (Long Term Evolution) system is standardized by 3GPP (3rd Generation Partnership Project). In LTE, radio resources used for radio communication between a radio base station and a radio terminal are allocated in units of resource blocks. The radio base station and the radio terminal execute data uplink transfer and downlink transfer using assigned radio resources. Radio resources are allocated according to channel quality of radio communication, data transmission amount, and the like.

  When a wireless terminal needs uplink radio resources to transmit a buffer status report (BSR: Buffer Status Report), a power headroom report (PHR: Power Headroom Report), etc., the wireless terminal requests a radio resource allocation request ( SR: Scheduling Request) is transmitted to the radio base station (see Non-Patent Document 1).

  The radio base station that has received the SR executes a scheduler function and allocates uplink radio resources to the radio terminal that has transmitted the SR. When the uplink radio resource allocation is completed, an uplink grant, which is radio resource allocation information, is transmitted from the radio base station to the radio terminal.

  When the radio terminal receives the uplink grant, the radio terminal recognizes that the uplink radio resource allocation has been completed, and transmits data using the uplink radio resource corresponding to the uplink grant.

  However, the uplink radio resource may not be allocated to the radio terminal due to a reason that the radio link is congested in the radio base station. If the uplink radio resource cannot be allocated in the radio base station, the SR needs to be transmitted again from the radio terminal.

3GPP TS 36.321 V8.3.0 (2008-09), “Medium Access Control protocol specification”

  Accordingly, an object of the present invention, which has been made in view of the above problems, is to provide a radio base station and a radio communication system that reduce the repeated transmission of SR from a radio terminal.

In order to solve the above-described problems, a radio base station according to the present invention
A wireless base station that communicates with a wireless terminal,
A scheduling unit that executes a scheduler function for allocating uplink radio resources to radio terminals;
When receiving a transmission interval from when a radio resource allocation request is transmitted together with a radio resource allocation request transmitted from a radio terminal to when it is transmitted again , the scheduling unit executes a scheduler function, and the scheduling unit executes the uplink radio resource when unable to assign, to within the time transmission interval, is characterized in that a control unit repeating retry scheduler function to be able to allocate uplink radio resources.

A wireless communication system according to the present invention includes:
A scheduling unit that executes a scheduler function for the allocation of uplink radio resources to non-linear terminal and the wireless terminal a wireless communication system having a radio base station,
When receiving a transmission interval from when a radio resource allocation request is transmitted together with a radio resource allocation request transmitted from a radio terminal to when it is transmitted again , the scheduling unit executes a scheduler function and the scheduling unit executes the uplink radio resource when unable to assign, to within the time of the transmission interval, and a radio base station having said uplink radio control unit to repeat a retry of a scheduler operable can assign source
And it is characterized in and this.

  As described above, the solution of the present invention has been described as a radio communication base station and a radio communication system. However, the present invention can also be realized as a method, a program, and a storage medium storing the program substantially corresponding to these. It should be understood that these are included in the scope of the present invention.

  According to the radio base station according to the present invention configured as described above, the scheduler function is retried when uplink radio resources cannot be allocated, and therefore, unnecessary SR transmission from the radio terminal is unnecessary. It becomes.

It is a figure which shows schematic structure of the radio | wireless communications system which concerns on one Embodiment of this invention. It is a flowchart which shows the process for the uplink radio | wireless resource allocation performed with a radio base station. It is a timing chart for demonstrating the process of the radio | wireless resource allocation between the conventional wireless base station and a wireless terminal. It is a timing chart for demonstrating the process of radio | wireless resource allocation between the radio base station and radio | wireless terminal of this embodiment.

  Hereinafter, embodiments of a radio base station and a radio communication system to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a radio communication system having a radio base station according to an embodiment of the present invention. The radio communication system 1 conforms to, for example, LTE, and the radio base station 10 according to the present embodiment provides different radio resources to a plurality of radio terminals 20 (only a single radio terminal is shown in FIG. 1). A block is allocated and wireless communication is performed between the wireless base station 10 and the plurality of wireless terminals 20.

  The wireless terminal 20 includes a wireless communication unit 21 and a control unit 22. The wireless communication unit 21 performs wireless communication with the wireless base station 10. That is, the wireless communication unit 21 receives downlink data. Further, the radio communication unit 21 transmits uplink data to the radio base station 10 using radio resources allocated by the radio base station 10. Further, the radio communication unit 21 can transmit an SR to the radio base station 10 and receive an uplink grant.

  When the wireless communication unit 21 receives the downlink data, the control unit 22 controls each part of the wireless terminal 20 according to the downlink data. Further, uplink data transmitted from the wireless communication unit 21 is generated by the control unit 22 according to the operation of each part of the wireless terminal 20 and transmitted to the wireless communication unit 21.

  Furthermore, the control unit 22 generates SR when transmitting BSR and PHR, and transmits the SR to the wireless communication unit 21. The SR transmission interval Tsr can be set for each radio terminal 20 and is transmitted to the radio base station 10 together with the SR.

  Moreover, the control part 22 recognizes the uplink radio | wireless resource for transmitting uplink data based on the uplink grant produced | generated based on SR in the wireless base station 10, so that it may mention later.

  The radio base station 10 includes a radio communication unit 11, a control unit 12, a scheduling unit 13, a ROM 14, a counter 15, and the like. The wireless communication unit 11 performs wireless communication with the wireless terminal 20. That is, the wireless communication unit 11 transmits downlink data. Further, the radio communication unit 11 receives uplink data transmitted from the radio terminal 20 using radio resources allocated by the radio base station 10. Further, the radio communication unit 11 receives the SR transmitted by the radio terminal 20 and transmits an uplink grant that is radio resource allocation information.

  Uplink data is transmitted from the wireless communication unit 11 to the control unit 12. The control unit 12 transmits uplink data to a network (not shown). Further, the control unit 12 transmits downlink data to be transmitted to the wireless terminal received from the network to the wireless communication unit 11.

  In addition, SR is transmitted from the wireless communication unit 11 to the control unit 12. When the SR is transmitted, the control unit 12 causes the scheduling unit 13 to execute the scheduler function. By executing the scheduler function, uplink radio resources are allocated to the radio terminal 20 that has transmitted the SR.

  When the uplink radio resource allocation is completed, an uplink grant that is allocation information of the radio resource allocated by the scheduling unit 13 is generated and transmitted to the radio communication unit 11.

  The radio base station 10 transmits / receives uplink data and downlink data to / from a plurality of radio terminals 20. Therefore, radio link congestion, that is, the free capacity of radio resources, may be insufficient for allocation of new radio resources. In such a case, the scheduling unit 13 cannot allocate uplink radio resources.

  When the control unit 12 causes the scheduling unit 13 to execute the scheduler function, the control unit 12 determines whether the assignment is completed. If the allocation is impossible, the control unit 12 causes the scheduling unit 13 to retry the scheduler function after the first time has elapsed. The first time is determined, for example, as a processing unit time defined in the wireless communication system 1, for example, a subframe (1 ms) in a wireless frame.

  Thereafter, the control unit 12 causes the scheduling unit 13 to retry the scheduler function until the uplink radio resource allocation is completed or the number of allocation failures reaches the first number. Note that a counter 15 is connected to the control unit 12, and the counter 15 detects the number of executions of the scheduler function.

  The first number of times is changed according to the SR transmission interval Tsr for each radio terminal 20. The first number of times Nrt is the SR transmission interval Tsr (ms) from the radio terminal 20, the first time Trt (ms), from the time of transmission from the uplink grant radio base station 10 until the radio terminal 20 receives it. The time Ttr is determined so as to satisfy Tsr> Nrt × Trt + Ttr.

  The first number of times corresponding to the SR transmission interval Tsr is stored in the ROM 14 as table data. As described above, since the transmission interval Tsr is notified together with the SR, the number of times corresponding to the transmission time notified when the SR is received is read out by the control unit 12.

  Next, processing for radio resource allocation executed by the radio base station 10 when receiving SR from the radio terminal 20 will be described with reference to the flowchart of FIG. Note that the processing for radio resource allocation starts when the radio base station 10 receives the SR transmitted from the radio terminal 20.

  In step S100, the control unit 12 recognizes the transmission interval Tsr received together with the SR. After recognizing the transmission interval Tsr, the process proceeds to step S101.

  In step S101, the control unit 12 resets the number of executions of the scheduler function in the counter 14 to zero. If reset to zero, the process proceeds to step S102.

  In step S102, the control unit 12 reads the number of times corresponding to the time interval Tsr recognized in step S100 from the ROM 14, and sets it to the first number. After setting the first number of times, the process proceeds to step S103.

  In step S103, the control unit 12 causes the scheduling unit 13 to execute a scheduler function. After execution of the scheduler function, the process proceeds to step S104.

  In step S104, the control unit 12 determines whether or not uplink radio resource assignment has been completed. When the assignment is not completed, the process proceeds to step S105. When the assignment is completed, the process proceeds to step S107.

  In step S105, the control unit 12 controls the counter 15 so that the number of executions of the scheduler function is incremented by +1. After measuring the number of executions, in the next step S106, it is determined whether or not the number of executions is less than the first number set in step S102. If it is less than the first number, the process returns to step S105. On the other hand, when the first number of times is reached, the allocation of radio resources is abandoned and the process for allocation ends.

  On the other hand, in step S107, the control unit 12 generates an uplink grant corresponding to the radio resource allocated to the scheduling unit 13. Furthermore, in the next step S108, the uplink grant is transmitted to the radio communication unit 11. After transmission of the uplink grant, the process for allocation is terminated.

  According to the radio base station 10 of the present embodiment configured as described above, it is possible to retry uplink radio resource allocation a plurality of times for the first SR received from the radio terminal 20 as described above. Is possible. Therefore, useless repetition of SR transmission from the radio terminal 20 can be reduced.

  In addition, it is possible to shorten the elapsed time from the time of the first SR reception until the completion of uplink radio resource allocation. The shortening of the elapsed time will be described with reference to FIGS. FIG. 3 is a timing chart for explaining processing of radio resource allocation between a conventional radio base station and a radio terminal. FIG. 4 is a timing chart for explaining processing of radio resource allocation between the radio base station and the radio terminal in the present embodiment.

  As shown in FIG. 3, in the conventional radio base station, the scheduler function has been tried once for a single SR transmission from the radio terminal. If the radio resource cannot be allocated after the scheduler function is implemented, the uplink grant is not transmitted. Therefore, if the radio terminal cannot receive the uplink grant, it transmits another SR when a predetermined time interval Tsr has elapsed since the previous SR transmission.

  The trial of the SR transmission and the scheduler function is repeated until the allocation of radio resources is completed in the radio base station. When the allocation of radio resources is completed in the radio base station, an uplink grant is transmitted from the radio base station, and transmission of uplink data from the radio terminal is started. Therefore, it takes at least ((the number of SR transmissions) × (the SR transmission interval) before the uplink data transmission starts after the SR transmission.

  On the other hand, in the present embodiment, as shown in FIG. 4, even if radio resource allocation fails, retry of the scheduler function is repeated before receiving another SR. Therefore, since the retry of the scheduler function is repeated, the possibility of successful radio resource allocation by a single SR is higher than that of the conventional radio base station. Therefore, there is an increased possibility that the time taken to complete the allocation of radio resources is shortened compared to the conventional radio base station.

  Further, according to the radio base station 10 of the present embodiment, since the upper limit value of the retry count of the scheduler function is determined for one SR reception, the time until the radio resource allocation is completed is shortened. However, an excessive load on the radio base station 10 is prevented. By retrying the scheduler function, it is possible to shorten the time taken to complete the allocation of radio resources. On the other hand, the load on the radio base station 10 increases as the number of retries increases. Therefore, it is possible to prevent an extreme increase in the load on the radio base station 10 by setting an upper limit value as in this embodiment.

  Also, according to the radio base station of the present embodiment, the first number that is the upper limit value of the number of retries is appropriately changed according to the SR transmission interval Tsr from the radio terminal 20. For example, when the first number is a fixed value and the transmission interval Tsr is relatively short, the scheduler function is retried according to the first SR even if the second and subsequent SRs are received. May be repeated. However, according to the present embodiment, it is possible to terminate the retry of the scheduler function before receiving another SR.

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

  For example, the first time is configured to be a processing unit time defined in the wireless communication system 1, but is not limited to the processing unit time. If the time is shorter than the shortest SR transmission interval by the wireless terminal 20, the same effect as in the present embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 10 Wireless base station 11 Wireless communication part 12 Control part 13 Scheduling part 15 Counter 20 Wireless terminal

Claims (4)

A wireless base station that communicates with a wireless terminal,
A scheduling unit that executes a scheduler function for allocating uplink radio resources to the radio terminal;
When receiving a transmission interval from when the radio resource allocation request is transmitted together with a radio resource allocation request transmitted from the radio terminal until it is transmitted again , the scheduling unit executes the scheduler function, and the scheduling unit when unable allocation of uplink radio resources, the radio base, characterized in that it comprises said up within a time transmission interval, said control unit to repeat a retry of the scheduler function to be able to allocate uplink radio resources Bureau. The radio base station according to claim 1,
The radio base station , wherein the control unit calculates the number of times the scheduler function is retried so that an uplink radio resource allocation response can be transmitted to the radio terminal within the transmission interval . The radio base station according to claim 2 ,
The radio base station , wherein the control unit calculates the number of times by using a time from when the uplink radio resource cannot be allocated until the scheduler function is retried . The continuously line terminal and a radio communication system having a radio base station,
The radio base station is
A scheduling unit that executes a scheduler function for allocating uplink radio resources to the radio terminal;
The scheduling unit executes the scheduler function when receiving a transmission interval from when the radio resource allocation request is transmitted together with the radio resource allocation request transmitted from the radio terminal to when it is transmitted again , and the scheduling unit if not made the allocation of the uplink radio resource, and the up within a time transmission interval, the uplink radio to the radio base station and a control unit repeating retry the scheduler function to be able to be allocated source A wireless communication system comprising:

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