JP2005045561A - Packet transmission scheduling device and its method, and radio base station device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet transmission scheduling device, its method, and a radio base station device by which packets can be efficiently distributed to respective transmitting destinations so that time required for scheduling is shortened and resources for packet transmission are usefully utilized and the throughput of a packet transmission system can be improved. <P>SOLUTION: A transmission destination selection part 203 suitably selects a transmission destination matched with a set condition from a transmitting destination candidate group by comparing the priority of all transmission destination candidates which are rearranged in the descending order of priority and inputted from a sorting part 202 with several preset thresholds. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio base station apparatus constituting a packet communication system, a scheduling apparatus that performs packet transmission control, and a method thereof.

  Conventionally, as a higher-speed IMT-2000 packet transmission method, a method called HSDPA (High Speed Downlink Packet Access) for the purpose of increasing the downlink peak transmission rate and increasing the throughput has been studied.

  In this high-speed packet communication system, services by various applications such as voice, moving image, and data transmission are expected. Therefore, a packet control technique that takes into account various QoS (Quality of Service) requirements is essential. The QoS request value includes an error rate required from an upper layer, an allowable delay time, a transmission rate, fluctuation, a packet discard rate, and the like.

  A typical example of the control technique is scheduling of packet transmission. Scheduling is a technology that determines how much downlink channel resources are allocated to which destination, and performs control such as determining the priority order during transmission for packets waiting to be transmitted in a single or multiple transmission buffers. Do. In addition, since the scheduling greatly affects the throughput in the packet communication system, various ideas have been made.

  Currently, as representative scheduling, there are three typical CIR schemes (hereinafter referred to as Max C / I scheme), Round Robin scheme (hereinafter referred to as RR scheme) and Proportional Fairness scheme (hereinafter referred to as PF scheme). There are types. In the Max C / I system, a transmission opportunity is assigned with higher priority to a mobile station (MT) with better radio link quality. In the RR scheme, transmission opportunities are equally allocated to all MTs. In the PF system, (instantaneous radio link quality) / (average radio link quality) or the like is used as a metric, and a transmission opportunity is preferentially assigned to an MT having a larger metric.

  Non-Patent Document 1 is known for a radio base station apparatus that performs packet transmission control by scheduling. FIG. 6 shows an outline of the scheduling method of this radio base station apparatus.

  This radio base station apparatus has a queue that temporarily holds packets for each MT that is a transmission destination. When the MT uses the QoS guaranteed service and the best effort (BE) service at the same time, it has a queue for each service class. Here, the BE service indicates a service that does not guarantee a delay time. The service class indicates the QoS stage to be guaranteed.

  The radio base station apparatus identifies the MT and the service class from the input packet, and inserts the packet into the corresponding queue. The queue of the MT in which the provided QoS level cannot afford the requested level belongs to the QoS critical group, and if the QoS level sufficiently satisfies the QoS level, it belongs to the QoS non-critical group. Also, MT queues that do not require QoS are classified into BE groups.

  A transmission opportunity is assigned with the highest priority to the queue of the QoS critical group. For this reason, the QoS critical group and other groups are selected by the PRR (Priority Round Robin) method. In other words, if there is a packet waiting for transmission in the queue of the QoS critical group, a transmission opportunity is always preferentially assigned even if it interrupts the service of a queue belonging to another group.

  In the QoS critical group, transmission opportunities are distributed according to the current QoS guarantee implementation condition and the like. The selection of the QoS non-critical group or the BE group is determined by scheduling based on the WRR (Weighted Round Robin) method after weighting based on the surplus bandwidth distribution policy for the QoS guaranteed service and the BE service.

  For the packet queues in the QoS non-critical group, since QoS is already guaranteed, scheduling is performed by the Max C / I method in order to increase the system capacity as much as possible.

  The packet queues in the BE group are weighted according to the radio link quality with the MT, and are scheduled by the PF method.

  FIG. 7 is a block diagram showing a configuration of a packet transmission scheduling apparatus (hereinafter referred to as “scheduler”) 10 provided in such a radio base station apparatus. The scheduler 10 includes a priority calculation unit 11, a sorting unit 12, a user selection unit 13, a modulation / coding control unit 14, a resource management unit 15, and a resource allocation unit 16.

  The priority calculation unit 11 includes memory information such as the amount of data stored in a memory unit (not shown) and its residence time, priority information about each transmission destination, and an ACK (ACKnowledge) signal transmitted from each transmission destination, Priorities for all transmission destinations are calculated based on a NACK signal, a CQI (Channel Quality Indicator) signal, and the like.

  The sorting unit 12 sorts the transmission destinations in descending order of priority based on the priority for each transmission destination input from the priority calculation unit 11.

  The user selection unit 13 selects the transmission destinations rearranged in the sorting unit 12 one by one in descending order of priority, and selects information about the selected transmission destinations in the modulation and coding control unit 14, the resource allocation The data is input to the unit 16 and a data combination unit (not shown).

  The resource management unit 15 receives the resource amount for packet communication as resource information, and notifies the resource allocation unit 16 of the resource amount that can be used at one transmission timing. Further, the resource management unit 15 inputs to the user selection unit 13 so as to output information about a transmission destination with the next highest priority when resources are allocated to each transmission destination by the resource allocation unit 16. In addition, the resource management unit 15 notifies the resource allocation unit 16 of resources that can be used at one transmission timing in consideration of the resources allocated by the resource allocation unit 16.

  The resource allocation unit 16 allocates a resource such as a code (code) and power for each transmission destination selected by the user selection unit 13 and reports the allocated resource to the resource management unit 15 and the modulation and coding control unit 14. Note that the memory information input to the priority calculation unit 11 is input to the resource allocation unit 16 in parallel, and data of each transmission destination stored in a memory unit (not shown) is a resource allocated to each transmission destination. Each one is inspected for possible modulation.

  The modulation and coding control unit 14 receives, in parallel, the ACK signal, NACK signal, or CQI signal for each transmission destination that is input to the priority calculation unit 11, and the resource allocation unit 16 assigns the resource allocated to each transmission destination. A coding rate, a modulation scheme, and the like that can be used within the range are determined, and an instruction based on the determination is input to a modulation coding unit (not shown).

  Therefore, in the conventional scheduler 10, resources are first allocated by the resource allocation unit 16 to the transmission destination having the highest priority selected by the user selection unit 13, and information on the allocated resources is stored in the resource allocation unit 16. To the resource management unit 15 and the modulation and coding control unit 14.

  Subsequently, the resource management unit 15 subtracts the resources already allocated from all the available resources at one transmission timing, and notifies the resource allocation unit 16 of the remaining resources. Along with this notification, the resource management unit 15 instructs the user selection unit 13 to output information on the transmission destination having the second highest priority.

Subsequently, in the user selection unit 13, the modulation and coding control unit 14, the resource allocation unit 16, and the data combining unit are the same as when the information about the second highest priority transmission destination is the highest priority transmission destination. Respectively. The modulation and coding control unit 14 sets a coding rate and the like for each transmission destination every time there is an input from the user selection unit 13 and the resource allocation unit 16. As described above, in the conventional scheduler 10, resources are sequentially assigned to each transmission destination, and the coding rate and the like are set.
Masahiro Ono and three others, "Proposal of ALL-IP mobile network architecture (3)-Examination of QoS guaranteed packet scheduler in base station", IEICE Technical Report, IEICE, May 2002, MoMuC2002 -3, p. 13-18

  However, in the conventional scheduler 10, the Max C / I method, the RR method, or the PF method is properly used according to the service class for packet transmission. Further, in each service class, according to the priority for each transmission destination. Thus, the coding rate and the like are set after the resources are sequentially allocated. Therefore, in the conventional scheduler 10, the scheduling algorithm in packet transmission control is complicated, and particularly when a packet is transmitted to a plurality of MTs at one transmission timing, there is a problem that the processing calculation amount and the processing time increase. is there. At this time, since it takes longer for the radio base station apparatus to transmit the packet after the reception quality of the MT as the transmission destination is notified, changes in the propagation path environment due to the movement of the MT during that time are also ignored. become unable. This means that communication that fully considers the propagation path environment cannot be performed, which causes a decrease in throughput in the packet communication system. In other words, since the conventional scheduler 10 uses an old CQI signal, selection of a transmission destination and setting of a coding rate and the like cannot be performed in a timely manner, so that packet transmission fails or resources cannot be used effectively. Thus, there is a problem that the throughput in the packet communication system is lowered.

  In order to avoid these problems, a method is conceivable in which a transmission destination is selected from a plurality of transmission destination candidates in advance, and resources that can be used at one transmission timing are allocated in advance. However, in this method, the number of destinations is constant regardless of the amount of resources that can be used, so resources are also assigned to destinations with relatively low priority, and resources assigned to users with high priority. Will decrease.

  Therefore, a method of changing the resource allocation according to the priority is conceivable so that the resources allocated to the transmission destination with a high priority do not decrease. However, in this method, when there is a difference in priority among a plurality of transmission destinations, resources are hardly allocated to a transmission destination with a low priority, so such a transmission destination is out of range (Out of Range). There is a problem that the packet cannot be received (the allocated resource is too small to be received regardless of how the coding rate and the modulation method are adjusted), and the resources that cannot be received are wasted.

  The present invention has been made in view of the above points, and reduces the amount of processing calculation to shorten the time required for scheduling, and does not allocate resources to a destination that is so small that the allocated resources cannot be received. An object of the present invention is to provide a packet transmission scheduling apparatus, a method thereof, and a radio base station apparatus capable of efficiently allocating resources and improving throughput in a packet communication system.

  The packet transmission scheduling apparatus according to the present invention includes a priority calculation unit that calculates a priority for each of a plurality of transmission destination candidates, and the transmission whose priority is less than a threshold based on the plurality of calculated priorities. A configuration is adopted that includes a selection unit that selects a transmission destination from the transmission destination candidate group except for a destination candidate, and an allocation unit that allocates a packet transmission resource for each of the selected transmission destinations.

  According to this configuration, when the resource that is proportionally distributed according to the priority is so small that it cannot be received at the transmission destination, the resource that should be allocated to such a transmission destination candidate is selected by the selection unit and other resources having a higher priority. Since transmission to the transmission destination is possible, useless resources that cannot be received in the packet communication system can be reduced, and as a result, the throughput can be improved.

  The packet transmission scheduling apparatus according to the present invention is the packet transmission scheduling apparatus according to the present invention, wherein the selection unit is set based on a ratio of the priority for each transmission destination candidate to a maximum value of the priority in the transmission destination candidate group. A configuration is adopted in which the transmission destination is selected from the transmission destination candidate group using a threshold value.

  According to this configuration, in addition to the effects of the present invention, it is possible to select transmission destinations at a constant ratio regardless of the magnitude of the maximum priority value. Thus, resources that can be used at one transmission timing can be appropriately allocated to each transmission destination.

  The packet transmission scheduling apparatus according to the present invention employs a configuration in which, in the above invention, the selection unit selects the transmission destination from the transmission destination candidate group in the descending order of priority.

  According to this configuration, in addition to the effect of the present invention, since the upper limit number of transmission destinations at one transmission timing is set, among the limited usable resources, the minimum is required because packets are received at the transmission destination. Since it is easy to secure necessary resources, it is possible to reduce resources that are wasted in the packet communication system and improve the throughput.

  The packet transmission scheduling apparatus according to the present invention, in the above invention, employs a configuration in which the allocation means proportionally distributes the packet transmission resources based on the priority for each selected transmission destination.

  According to this configuration, in addition to the effects of the invention, resources that can be used at one transmission timing are proportionally distributed according to the priority of the transmission destination, so that packets can be transmitted in a balanced manner to a plurality of transmission destinations. Can do.

  The packet transmission scheduling apparatus according to the present invention is the packet transmission scheduling apparatus according to the present invention, wherein, when the maximum value of the priority in the transmission destination candidate group exceeds a reference value, the selection unit selects the priority from the transmission destination candidate group. A configuration is adopted in which only the transmission destination having the maximum degree is selected.

  According to this configuration, in addition to the effect of the invention, a destination that is considered to be extremely urgent about packet transmission can be identified by comparing with a reference value. By assigning all the resources that can be used in the network, the adaptability of the entire packet communication system can be improved.

  The packet transmission scheduling apparatus according to the present invention is the packet transmission scheduling apparatus according to the present invention, wherein the selection means includes a transmission waiting data amount, a data transmission waiting time, data priority information according to a service class, packet delivery confirmation information, packet transmission resource information, A configuration is adopted in which the priority for each transmission destination candidate is calculated based on at least one piece of information selected from the group consisting of past throughput information, reception capability information of the receiving communication apparatus, and propagation path information.

  According to this configuration, in addition to the effects of the present invention, information such as the amount of data waiting to be transmitted is reflected in the priority of each transmission destination candidate, thereby suppressing the excess or deficiency of resources allocated to each transmission destination. The quality of service in the packet communication system can be maintained.

  The packet transmission scheduling apparatus according to the present invention employs a configuration in which, in the above invention, the selection unit adjusts the threshold according to the total amount of resources that can be used at one transmission timing.

  According to this configuration, in addition to the effects of the present invention, it is possible to reduce wasteful resources that cannot be received due to too few resources allocated to each destination, and as a result, the throughput of the packet communication system is effectively reduced. Can be improved.

  The radio base station apparatus according to the present invention employs a configuration including the packet transmission scheduling apparatus.

  According to this configuration, when the resource that is proportionally distributed according to the priority is so small that it cannot be received at the transmission destination, the resource that should be allocated to such a transmission destination candidate is selected by the selection unit and other resources having a higher priority. Since it can be transferred to the transmission destination, useless resources that cannot be received in the packet communication system can be reduced, and as a result, the throughput can be improved.

  The packet transmission scheduling method according to the present invention includes a priority calculation step of calculating a priority for each of a plurality of transmission destination candidates, and the transmission in which the priority is less than a threshold based on the plurality of calculated priorities. A selection step for selecting a transmission destination from the transmission destination candidate group, excluding destination candidates, and an allocation step for allocating a packet transmission resource for each of the selected transmission destinations are provided.

  According to this method, when the resource that is proportionally distributed according to the priority is so small that it cannot be received at the transmission destination, the resource that should be allocated to such a transmission destination candidate is selected at the selection step. Since it can be transferred to the transmission destination, useless resources that cannot be received in the packet communication system can be reduced, and as a result, the throughput can be improved.

  As described above, according to the present invention, when the resource proportionally distributed according to the priority is so small that it cannot be received at the transmission destination, the resource that should be allocated to such a transmission destination candidate is selected by the selection means. Since it can be transferred to another transmission destination with high priority, useless resources that cannot transmit information in the packet communication system can be reduced, and as a result, the throughput can be improved.

  Further, according to the present invention, when a transmission destination is selected from the transmission destination candidate group in the packet transmission scheduling apparatus, a resource is assigned to each transmission destination after all the transmission destinations at one transmission timing are selected. Therefore, it is possible to reduce the load of signal processing for resource allocation, and it is possible to reduce the time required to allocate resources to each transmission destination at a predetermined ratio.

  The gist of the present invention is to calculate priorities for packet transmission for each of a plurality of transmission destination candidates, and to use packet transmission resources (hereinafter simply referred to as “resources”) that can be used at one transmission timing according to the calculated priorities. Can be received if the resources are proportionally distributed according to the priority of each destination candidate. By setting a threshold so that resources are not assigned to destinations with lower priority, the resources that should be assigned to destinations with a priority lower than the threshold are set to destinations with a priority higher than the threshold. It is to transfer and use efficiently.

  Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings as appropriate. In this embodiment, a radio base station apparatus based on the HSDPA scheme using the W-CDMA scheme and a packet transmission scheduling method using this radio base station device will be described as an example. However, the packet transmission scheduling apparatus according to the present invention will be described. The method and the radio base station apparatus can be applied to other communication systems.

  FIG. 1 is a block diagram showing a configuration of radio base station apparatus 100 according to the present embodiment.

  The radio base station apparatus 100 includes a memory unit 101, a data combination unit 102, a modulation and coding unit 103, a transmission unit 104, an antenna duplexer 105, a scheduler 106, a reception unit 107, an ACK / NACK / CQI extraction unit 108, and an antenna element 109. It comprises.

  The memory unit 101 holds data destined for each transmission destination candidate input from a host station device (not shown) for a predetermined period. In addition, the memory unit 101 inputs information about the usage status of the memory, for example, the free capacity, to the scheduler 106.

  The data combining unit 102 extracts data to be actually transmitted from the memory unit 101 in accordance with an instruction from the scheduler 106, and packetizes the extracted data by performing processing such as combining. The data combining unit 102 generates a packet individually for each transmission destination. The generated packets for each transmission destination are temporarily held in a transmission unit 104 described later, and the held packets are multiplexed by a known technique such as code division multiplexing. Then, at one transmission timing, the multiplexed packet is simultaneously transmitted from the antenna element 109 described later to each transmission destination.

  The modulation encoding unit 103 performs each process such as encoding and modulation on the packet addressed to each transmission destination input from the data combining unit 102 under the conditions instructed by the scheduler 106.

  The transmission unit 104 performs known transmission signal processing such as spreading, frequency conversion, and amplification on the packet addressed to each destination input from the modulation and coding unit 103.

  The antenna duplexer 105 outputs a packet input from the transmission unit 104 to the antenna element 109, and inputs a reception signal input from the antenna element 109 to the reception unit 107.

  The scheduler 106 receives priority information about data destined for each destination input from the higher station apparatus, memory information input from the memory unit 101, and input from the ACK / NACK / CQI extraction unit 108. Based on the ACK signal, NACK signal, or CQI signal of each transmission destination candidate, the packet size (Transport Block Size), the coding rate, the modulation method, and the like are determined for each transmission destination, and the determination is performed by the data combining unit. 102 and the modulation encoding unit 103 are instructed to perform processing under predetermined conditions.

  The receiving unit 107 performs known reception signal processing such as amplification, frequency conversion, despreading, and demodulation on the reception signal input from the antenna duplexer 105.

  The ACK / NACK / CQI extraction unit 108 receives an ACK signal or a NACK signal for a packet transmitted from the radio base station apparatus 100 from among the reception signals input from the reception unit 107, and a CQI signal indicating reception quality at the transmission destination candidate And the extracted signals are input to the scheduler 106.

  The antenna element 109 wirelessly transmits a packet input from the antenna duplexer 105, receives a radio signal transmitted from each transmission destination candidate, and inputs the received signal to the antenna duplexer 105.

  FIG. 2 is a block diagram showing the configuration of the scheduler 106. The scheduler 106 includes a priority calculation unit 201, a sorting unit 202, a transmission destination selection unit 203, a modulation / coding control unit 204, a resource management unit 205, and a resource allocation unit 206.

  The priority calculation unit 201 stores memory information such as the amount of data held in the memory unit 101 and its residence time, priority information about each transmission destination candidate, an ACK signal transmitted from the transmission destination candidate, a NACK signal through Priorities for all transmission destination candidates are calculated based on CQI signals and the like.

  The sorting unit 202 rearranges the transmission destination candidates in descending order of priority based on the priority for each transmission destination candidate input from the priority calculation unit 201.

  The transmission destination selection unit 203 compares the priorities of the transmission destination candidates input from the sorting unit 202 in descending order of priority with some preset threshold values, thereby comparing the transmission destination candidates. A transmission destination that meets the setting conditions is appropriately selected from the group. A specific operation in which the transmission destination selection unit 203 selects an appropriate transmission destination from the transmission destination candidate group will be described later. Then, transmission destination selection section 203 inputs information about the selected transmission destination to modulation and coding control section 204, resource allocation section 206, and data combining section 102, respectively.

  The resource management unit 205 receives a resource amount for high-speed packet communication from a higher-level station apparatus (not shown) as resource information, and notifies the resource allocation unit 206 of resources that can be used at one transmission timing.

  The resource allocating unit 206 proportionally distributes resources, that is, codes (codes), power, and the like notified from the resource management unit 205 to the plurality of transmission destinations selected by the transmission destination selection unit 203 according to the priority. Then, the allocated resources are reported to the modulation and coding control unit 204. Note that the memory information input to the priority calculation unit 201 is input to the resource allocation unit 206 in parallel, and the data of each transmission destination held in the memory unit 101 is modulated by the resource allocated to each transmission destination. Confirmed if possible.

  The modulation and coding control unit 204 receives, in parallel, the ACK signal, NACK signal, or CQI signal for each transmission destination input to the priority calculation unit 201, and the resource allocation unit 206 assigns the resource allocated to each transmission destination. An encoding rate, a modulation scheme, and the like that can be used within the range are determined, and an instruction based on this determination is input to the modulation encoding unit 103.

  FIG. 3 is a block diagram illustrating a configuration of the transmission destination selection unit 203. The transmission destination selection unit 203 includes a priority maximum value selection unit 301, a multiplex reference value comparison unit 302, a multiplex threshold comparison unit 303, a maximum multiplex number comparison unit 304, a multiplex threshold calculation unit 305, and a memory unit 306.

  The priority maximum value selection unit 301 selects a transmission destination candidate with the highest priority based on the priorities of the transmission destination candidates sorted in descending order of priority input from the sorting unit 202. Measure the maximum value.

  The multiple reference value comparison unit 302 compares the preset multiple reference value (absolute value) input from the memory unit 306 with the maximum priority value input from the priority maximum value selection unit 301. To do. Then, when the maximum priority value exceeds the multiplex reference value, the multiplex reference value comparison unit 302 selects a transmission destination candidate having the highest priority as a transmission destination and can be used at one transmission timing. All resources are assigned to the destination with the highest priority. In this case, since resources are not allocated to other transmission destination candidates, the comparison in the multiplex threshold comparison unit 303 and the maximum multiplex number comparison unit 304 described later is not performed, and the packet is not multiplexed in the transmission unit 104. . On the other hand, when the maximum priority value does not exceed the multiplex reference value, the multiplex reference value comparison unit 302 directly compares the priority for each transmission candidate input from the priority maximum value selection unit 301 with the multiplex threshold comparison. Let the part 303 pass.

  The multiple threshold value calculation unit 305 multiplies the maximum priority value input from the priority maximum value selection unit 301 by a ratio to the preset maximum priority value input from the memory unit 306. The multiple threshold is calculated. Specifically, for example, when the maximum priority value is “10” and the ratio to the maximum priority value is “1/2”, the multiple threshold (absolute value) is “5”. . When the multiple threshold value is calculated by the multiple threshold value calculation unit 305, the multiple threshold value can also be calculated by setting a difference (absolute value) from the maximum priority value in advance and using this difference. . However, when the multiplex threshold value is calculated using the difference from the maximum priority value, the multiplex threshold value becomes negative depending on the magnitude of the maximum priority value, and all the transmission destination candidates are selected. It is assumed that the function as the threshold value cannot be exhibited. Therefore, it is preferable to use the ratio of the priority to the maximum value in the calculation of the multiple threshold. By using this ratio to the maximum priority value, the destination is selected regardless of the magnitude of the maximum priority value, so it is possible to avoid selecting too many or too few destinations. As a result, resources can be allocated more appropriately to each destination.

  The multiple threshold value comparison unit 303 compares the multiple threshold value input from the multiple threshold value calculation unit 305 with the priority of each transmission destination candidate that passes through the multiple reference value comparison unit 302, and transmits a transmission destination candidate group. A transmission destination candidate whose priority is equal to or higher than the multiplex threshold is selected as a transmission destination.

  The maximum multiplexing number comparison unit 304 compares the preset upper limit number of transmission destinations input from the memory unit 306 with the number of selected transmission destinations input from the multiplexing threshold value comparison unit 303. When the number of selected destinations exceeds the preset maximum number of destinations, the selected destination is set to the same number as the preset maximum number of destinations in order from the lowest priority Reduce until. Then, the maximum multiplex comparison unit 304 inputs information about transmission destinations selected below a preset upper limit number of transmission destinations to the resource allocation unit 206 and the like.

  Accordingly, the memory unit 306 includes a preset multiplex reference value input to the multiplex reference value comparison unit 302, a ratio to the maximum priority value input to the multiplex threshold value calculation unit 305, and a maximum multiplex number comparison unit 304. And the maximum multiplex number input to each. Each preset value stored in the memory unit 306 can be adjusted as appropriate in consideration of the propagation path environment, transmission resources, and the like.

  Incidentally, the multiplex reference value, the multiplex threshold value, and the maximum multiplex number each function as a threshold value when the transmission destination selection unit 203 selects a transmission destination from the transmission destination candidate group. Further, these threshold values may be appropriately adjusted according to the total amount of resources that can be used at one transmission timing. For example, when the amount of resources that can be used at one transmission timing is small, it is possible to prevent the resources allocated to each transmission destination from becoming too small by reducing the threshold value.

  Next, the operation of the transmission destination selection unit 203 will be specifically described with reference to the flowchart shown in FIG.

  In step ST410, after the priorities for the respective transmission destination candidates sorted in descending order of priority are input from the sorting unit 202 to the priority maximum value selecting unit 301, the priority maximum value selecting unit 301 determines the priorities. The largest destination candidate is selected and the priority of that destination candidate is measured.

  In step ST420, the maximum priority value measured in step ST410 is compared with the multiplex reference value (absolute value) set in advance and held in the memory unit 306, and the magnitude relationship is determined. Here, when the maximum priority value exceeds the multiplex reference value, only the transmission destination candidate with the highest priority is selected as the transmission destination, and all resources that can be used at one transmission timing are included in this transmission destination. Once assigned, the next step is step ST470. On the other hand, if the maximum priority value does not exceed the multiple reference value, the next step is step ST430.

  In step ST430, the multiple threshold calculation unit 305 multiplies the maximum priority value input from the priority maximum value selection unit 301 by a ratio to the maximum priority value input from the memory unit 306. Thus, the multiple threshold value is calculated.

  In step ST440, the multiple threshold value calculated in step ST430 is input from the multiple threshold value calculation unit 305 to the multiple threshold value comparison unit 303. In the multiple threshold value comparison unit 303, the priority is equal to or higher than the multiple threshold value and has not yet been selected. It is determined whether there is no transmission destination candidate. Here, in step ST440, when the priority is equal to or higher than the multiplex threshold and there is a transmission destination candidate that has not yet been selected, the next step is step ST450, while the transmission destination candidate does not exist. In that case, the next step is Step ST470.

  In step ST450, the multiple threshold value comparison unit 303 selects transmission destination candidates that have a priority level equal to or higher than the multiple threshold value and are not yet selected in order from the highest priority level.

  In step ST460, the maximum multiplexing number comparison section 304 has a cumulative number of transmission destination candidates selected in step ST450 at one transmission timing, and a preset upper limit number of transmission destinations inputted from the memory section 306, that is, the maximum. The magnitude relationship with the number of multiplexes is determined. Here, in step ST460, when the cumulative number of selected transmission destination candidates at one transmission timing is smaller than the maximum multiplexing number, the processing returns to step ST440 again and a transmission destination candidate is selected by the same procedure. On the other hand, when the number of selected transmission destination candidates reaches the maximum multiplexing number, the next step is step ST470.

  In step ST470, the transmission destination selected in step ST420 and step ST450 is formally determined as the transmission destination at one transmission timing. In step ST470, information on the transmission destination at the determined transmission timing is input from transmission destination selection section 203 to resource allocation section 206, modulation and coding control section 204, and data combining section 102.

  In FIG. 5, the priority for each transmission destination candidate rearranged in the descending order of priority input from the sorting unit 202 to the transmission destination selection unit 203 and a transmission destination are selected from the transmission destination candidate group. A plurality of examples in which various threshold values used in the above are combined are shown. In FIGS. 5A, 5B, 5C, and 5D, the transmission destination candidates A to J are arranged in descending order of priority.

  In the example of FIG. 5A, the priority of the transmission destination candidate A is the highest, and the priority does not exceed the multiplex reference value. Therefore, in the example of FIG. 5A, not only the transmission destination candidate A but also any of the transmission destination candidates B to J may be selected as the transmission destination. In the example of FIG. 5A, since the multiple threshold is set at a position 2/3 of the maximum priority value, the priority is selected as a transmission destination candidate, that is, a transmission destination having a priority equal to or higher than the multiple threshold. There are three possible transmission destination candidates, that is, transmission destination candidates A, B, and C. Here, if the maximum multiplexing number in the example of FIG. 5A is 6, for all of the transmission destination candidates A, B, and C, the rank regarding the high priority does not exceed this maximum multiplexing number. It will be. Therefore, in the example of FIG. 5A, three transmission destination candidates A, B, and C are selected as transmission destinations at one transmission timing, and one transmission timing is selected according to the ratio of these priorities. The resources that can be used in are allocated in proportion in the scheduler 106.

  Further, the example of FIG. 5B is an example in which, in the example of FIG. 5A, only the multiplex threshold value is lowered to a position of ½ with respect to the maximum priority value. In the example of FIG. 5B, as shown in FIG. 5, five destination candidates A, B, C, D, and E are selected as destinations.

  Further, the example of FIG. 5C is an example in which the five priorities of the transmission destination candidates A, B, C, D, and E are lowered in the order as they are in the example of FIG. 5B. Therefore, in the example of FIG. 5C, since the maximum value of the priority is lowered, all the priorities of the transmission destination candidates A to J are equal to or higher than the multiplex threshold. In the example of FIG. 5 (c), the maximum multiplexing number is 6, as shown in the figure, so that the highest priority order from the highest to the sixth, that is, transmission destination candidates A, B, C, D, Six of E and F are selected as transmission destinations.

  The example of FIG. 5D is an example in which the multiplex reference value is lower than the maximum priority value in the example of FIG. In the example of FIG. 5D, since the priority of the transmission destination candidate A exceeds the multiplex reference value, only the transmission destination candidate A is selected as the transmission destination. Although the priority of the transmission destination candidate B also exceeds the multiplex reference value, only the transmission destination candidate A is selected as the transmission destination. In this way, for a destination whose priority exceeds the multiplex reference value, it can be determined that the urgency of packet transmission is extremely high. Therefore, by assigning all available resources at one transmission timing to this destination, The adaptability of the entire packet communication system can be further enhanced. Also, if all the resources that can be used at one transmission timing are assigned to one transmission destination, there is no need to multiplex packets in the transmission unit 104, and the amount of signal processing in the radio base station apparatus 100 is reduced. be able to. Furthermore, if the processing amount of signal processing in the radio base station apparatus 100 can be reduced, the time required for packet transmission scheduling can be shortened. Therefore, the response from the radio base station apparatus 100 to the transmission destination is improved, and packet communication is performed. Throughput in the system can be improved.

  As described above, according to radio base station apparatus 100 according to the present embodiment, when the resources that are proportionally distributed according to the priority are so small that they cannot be received at the transmission destination, transmission to such a transmission destination is performed. Can be transferred to other destinations with higher priority, so resources available at one transmission timing can be used more effectively, resulting in improved throughput in packet communication systems can do.

  Further, according to scheduler 106 according to the present embodiment, since all the transmission destinations at one transmission timing are selected within transmission destination selection section 203, transmission destination selection section 203 and modulation and coding control section It is not necessary to input / output signals one by one every time a transmission destination is selected between the 204, the resource management unit 205, and the resource allocation unit 206. As a result, the processing amount of signal processing in the scheduler 106 can be reduced, and transmission destination selection and resource allocation to each transmission destination can be performed in a shorter time.

  In the present invention, “destination” means a unit of use of various services in the packet communication system. For example, if one user uses two services simultaneously, the destination in the present invention is 2 Become one. Therefore, two priorities are calculated for the same user.

  In this embodiment, the case of performing packet transmission scheduling on the premise of the HSDPA method in the W-CDMA method has been described. However, the present invention is not limited to this case. For example, TDMA (Time Division Multiplexing Access) ) System and OFDM (Orthogonal Frequency Division Multiplexing) system packet communication system.

  The packet transmission scheduling apparatus, the method thereof, and the radio base station apparatus according to the present invention should be assigned to such a transmission destination candidate when the resources proportionally distributed according to the priority are so small that they cannot be received at the transmission destination. Can be transferred to another destination with a higher priority by the selection means, so that useless resources that cannot transmit information in the packet communication system can be reduced, and as a result, the throughput can be improved. This is effective, and is useful as a radio base station apparatus constituting an HSDPA communication system in the W-CDMA system, a scheduling apparatus that performs packet transmission control, and a method thereof.

The block diagram which shows the structure of the wireless base station apparatus which concerns on one embodiment of this invention The block diagram which shows the structure of the scheduler which concerns on one embodiment of this invention The block diagram which shows the structure of the transmission destination selection part which is a component of the scheduler which concerns on one embodiment of this invention The flowchart which shows operation | movement of the transmission destination selection part in this invention The figure which shows the relationship between the priority for every transmission destination candidate and several threshold value in one embodiment of this invention The figure which shows the outline | summary of the scheduling method in the conventional radio base station apparatus. A block diagram showing a configuration of a scheduler provided in a conventional radio base station apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Radio base station apparatus 101 Memory part 102 Data coupling part 103 Modulation encoding part 104 Transmission part 105 Antenna duplexer 106 Scheduler 107 Reception part 108 ACK / NACK and CQI extraction part 109 Antenna element 201 Priority calculation part 202 Sort part 203 Transmission Preselection unit 204 Modulation coding control unit 205 Resource management unit 206 Resource allocation unit 301 Maximum priority value selection unit 302 Multiplex reference value comparison unit 303 Multiplex threshold value comparison unit 304 Maximum multiplexing number comparison unit 305 Multiplex threshold value calculation unit 306 Memory unit

Claims (9)

Priority calculation means for calculating the priority for each of a plurality of transmission destination candidates;
Based on the plurality of calculated priorities, a selection unit that selects a transmission destination from the transmission destination candidate group excluding the transmission destination candidates whose priority is less than a threshold;
A packet transmission scheduling apparatus, comprising: allocating means for allocating a packet transmission resource for each of the selected transmission destinations.   The selection means uses the threshold value set based on a ratio of the priority for each transmission destination candidate to the maximum value of the priority in the transmission destination candidate group, and selects the transmission destination candidate group from the transmission destination candidate group. The packet transmission scheduling apparatus according to claim 1, wherein a transmission destination is selected.   The packet transmission scheduling apparatus according to claim 1, wherein the selection unit selects the transmission destination from the transmission destination candidate group in the descending order of priority.   The packet transmission scheduling apparatus according to claim 1, wherein the allocating unit proportionally distributes the packet transmission resource based on the priority for each selected transmission destination.   The selection means selects only the transmission destination having the highest priority from the transmission destination candidate group when the maximum value of the priority in the transmission destination candidate group exceeds a reference value. The packet transmission scheduling apparatus according to claim 1.   The selection means includes transmission waiting data amount, data transmission waiting time, data priority information according to service class, packet delivery confirmation information, packet transmission resource information, past throughput information, reception capability information of the receiving communication device, and 2. The packet transmission scheduling apparatus according to claim 1, wherein the priority for each of the transmission destination candidates is calculated based on at least one information selected from the group consisting of propagation path information.   The packet transmission scheduling apparatus according to claim 1, wherein the selection unit adjusts the threshold according to a total amount of resources that can be used at one transmission timing.   A radio base station apparatus comprising the packet transmission scheduling apparatus according to any one of claims 1 to 7. A priority calculating step for calculating a priority for each of a plurality of transmission destination candidates;
A selection step of selecting a transmission destination from the transmission destination candidate group based on the plurality of calculated priorities, excluding the transmission destination candidates whose priority is less than a threshold;
A packet transmission scheduling method comprising: allocating a packet transmission resource to each of the selected transmission destinations.

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