JP2016034089A - Radio communication base station and radio communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication base station capable of improving reception characteristics of uplink control signal while preventing interference among uplink control signals after code division multiplex.SOLUTION: The radio communication base station allocates a resource to a control signal. In the uplink control signal allocation, the radio communication base station prepares an uplink control signal management chart, and avoids from allocating to an uplink control signal which has been allocated and an uplink control signal resource to be subjected to code division multiplex.SELECTED DRAWING: Figure 1

Description

  The present invention relates to resource allocation to control signals by a radio communication base station.

  The wireless communication base station needs to communicate with a terminal that moves at high speed. In that case, when the radio communication base station receives radio waves transmitted from the terminal, the frequency of the radio waves may deviate from a predetermined value due to the Doppler effect. Therefore, when the radio communication base station receives the radio wave transmitted from the terminal, it is necessary to estimate and compensate for the frequency shift. Non-Patent Document 1 describes that the frequency shift of the uplink control signal is divided into two stages of rough compensation and fine compensation.

  The 3rd Generation Partnership Project (3GPP), a standardization organization for cellular radio communications, has developed a system called LTE (Long Term Evolution). In LTE, the uplink control signal channel is called PUCCH (Physical Uplink Control Channel). Non-Patent Document 2 describes a signal waveform generation method, and Non-Patent Document 3 describes a signal resource allocation method.

2012 12th International Conference on Electronic Packaging Technology and High Density Packaging (ICEPT-HDP), “Carrier frequency offset estimation for PUCCH in high speed train environment” 3GPP TS36.211 V10.5.0 3GPP TS36.213 V10.8.0

  In order to improve communication efficiency, uplink control signals transmitted from a plurality of terminals may be code division multiplexed and arranged in the same time / frequency region. In code division multiplexing, orthogonality between codes is lost depending on channel conditions, and interference occurs between multiplexed signals.

  For example, when the terminal moves at high speed, a frequency shift due to the Doppler effect occurs in the signal waveform received by the base station from the terminal. Since the moving direction and speed differ for each terminal, the magnitude of the Doppler effect also varies. For this reason, the magnitude of the frequency shift of the uplink control signal is different, the orthogonality between the code division multiplexed signals is lost, and interference occurs. Due to the influence of interference, it becomes difficult to separate code division multiplexed signals.

  A method for generating a signal waveform of an uplink control signal channel (PUCCH) in LTE is described in Non-Patent Document 2.

  FIG. 9 (same as Non-Patent Document 2 and FIG. 5.4.3-1) is a diagram showing the PUCCH resource allocation in LTE. In LTE, the time direction is divided into subframes having a time width of 1 ms, and signals are assigned using subframes as basic units. The Subframe is further divided into two slots, and the time width of the slots is 0.5 ms. The PUCCH is composed of a plurality of PUCCH regions (m = 0, 1,...), And resources of different frequencies are assigned to one PUCCH region in the first half slot and the second half slot. Several formats are defined in PUCCH. Among them, in format 1 / 1a / 1b, uplink control signals transmitted from a plurality of terminals are multiplexed by PUCCH region, cyclic shift, and orthogonal code division.

  As shown in FIG. 10, in PUCCH format 1 / 1a / 1b, there are 3 orthogonal codes (n_oc = 0, 1, 2) and 12 cyclic shifts in an OFDM (Orthogonal Frequency Division Multiplexing) signal. (N_cs = 0, 1,..., 11) is used, and a maximum of 36 control signals are multiplexed in one PUCCH region. Two signals multiplexed only by code division, that is, the same PUCCH region, only the orthogonal code is different by the same cyclic shift (m and n_cs are the same and only n_oc are different), between the two uplink control signals due to the loss of orthogonality Interference occurs.

  This problem can be avoided by using a setting that does not allow uplink control signals that differ only in code division.

  FIG. 11 is a diagram illustrating a state in which a set of (n_oc, n_cs) that can be used in the PUCCH region changes depending on the value of the parameter deltaPUCCH-Shift included in the broadcast information in LTE. Available elements are shown in white and unavailable elements are shown in black. If deltaPUCCH-Shift is set to 3, only one orthogonal code (n_oc) is used for one cyclic shift (n_cs), so that multiplexing of control signals that differ only in orthogonal codes can be avoided. However, since the set of (n_oc, n_cs) that can be used per PUCCH region is 1/3 times that in the case of deltaPUCCH-Shift = 1, the number of necessary PUCCH regions is three times as many. Since more resources are consumed for the PUCCH region, there is a problem that resources that can be used for data signals are reduced and throughput is reduced.

  In order to solve the above-mentioned problem, one of the resource allocation methods to control signals by a representative radio communication base station of the present invention is to prepare an uplink control signal management table in uplink control signal allocation, This avoids allocation to uplink control signal resources that differ only in orthogonal code from the control signal.

  Another aspect of the present invention is a radio communication control method for allocating uplink signal resources to a base station to a plurality of terminals, and the uplink signal resources are different from any one of frequency, orthogonal code, and cyclic shift. In multiplexing, the use of a plurality of the orthogonal codes is allowed for one cyclic shift, and at the time of allocation, only the orthogonal codes are used in at least some of the communications. Control so that different resources are not allocated at the same time.

  If the above control is performed only in a part of the communication, there is an effect of reducing the interference in the part, but the control can also be performed in the entire communication. It may be applied according to the required specifications of the system. In the control, only a terminal having a large moving speed and a large influence of the Doppler effect may be taken.

  Another aspect of the present invention is a base station that communicates with a plurality of terminals, and includes a scheduler that allocates uplink signal resources from the plurality of terminals to the plurality of terminals. The scheduler multiplexes and allocates uplink signal resources according to any one of frequency, orthogonal code, and cyclic shift, and uses multiple orthogonal codes for one cyclic shift in multiplexing. In the allocation, at least a part of the communication is controlled so that only the orthogonal code does not allocate a different resource. The control can be configured to be performed using a table in which a set of frequency, orthogonal code, and cyclic shift corresponds to one ID, for example, Resource index. The embodiments of the present invention disclose various specific examples in which the present invention is applied to a communication system compliant with LTE.

  According to the present invention, the amount of resources required for uplink control signals is suppressed by code division multiplexing, and at the same time, the interference between orthogonal codes is reduced to improve the reception characteristics of uplink control signals.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The flowchart which shows the form of the process sequence of Example 1 of this invention. Table showing example of uplink control signal management table Table showing an example of an uplink control signal management table when the present invention is applied to an LTE base station The flowchart which shows the form of the process sequence of Example 3 of this invention. The flowchart which shows the form of the process sequence of Example 4 of this invention. The flowchart which shows the form of the process sequence of step 304 of FIG. The flowchart which shows the form of the process sequence of step 305 of FIG. The flowchart which shows the form of the process sequence of step 306 of FIG. Diagram showing PUCCH resource allocation in LTE Diagram showing code division multiplexing and cyclic shift multiplexing in LTE PUCCH format 1 / 1a / 1b Diagram showing (n_oc, n_cs) pairs that can be used within LTE PUCCH region The figure which shows the structure of the base station of Example 5 of this invention.

  Embodiments will be described below with reference to the drawings. However, the present invention is not construed as being limited to the description of the embodiments below. Those skilled in the art will readily understand that the specific configuration can be changed without departing from the spirit or the spirit of the present invention. Publications, patents and patent applications cited in this specification form part of the description of the present specification as they are.

  FIG. 1 is a flowchart showing an embodiment of a processing procedure.

  FIG. 2 is an example of a table for managing resources of uplink control signals.

  In FIG. 2, the uplink control signal is managed by the resource index, and one terminal can be assigned to one resource index. In FIG. 2, it is assumed that uplink control signals are multiplexed by frequency, orthogonal code, and cyclic shift, and have numbers of frequency m, code n_oc, and cyclic shift n_cs, respectively. Assume that a set of (m, n_oc, n_cs) is uniquely determined for one Resource index according to one standard or the like. FIG. 2 holds the ID (UE ID) of the terminal assigned to each Resource index.

  The operation procedure of the flowchart of FIG. 1 is shown below.

  In step 101, an uplink control signal management table is initialized. Specifically, the UE ID is set to None (no assignment) for all resource indexes in the resource management table of the uplink control signal in FIG.

  In step 102, one terminal is selected from terminals that need to be assigned an uplink control signal. As the order of selection of terminals, for example, the order of small UE ID, the random order, or the priority order by QoS can be considered.

  In step 103, according to a standard or the like, a resource index candidate value for arranging the uplink control signal of the terminal selected in step 102 is calculated. Multiple Resource indexes may be candidates.

  In step 104, an available resource index is searched from the candidate values of the resource index obtained in step 103. Whether or not the resource index can be used is determined using the uplink control signal management table of FIG. The candidate value of Resource index is searched, the UE ID is read, and it is confirmed whether the Resource index has already been assigned. If another UE ID has been assigned, that resource index cannot be used.

  If the resource index has not been assigned, the resource index, m, and n_cs are the same and only the n_oc is searched for, and the UE ID is read. As a result, if it has already been assigned to another terminal, the candidate value of the resource index targeted here cannot be used. For example, since Resource index = 0 has a UE ID of None and only n_oc differs, Resource index = 12, 24 UE IDs are also None, so Resource index = 0 can be used. On the other hand, although the UE ID is None for Resource index = 1, the UE ID of Resource index = 13 for which n_oc = 1 is already assigned to the terminal with ID = 51. Therefore, if Resource index = 1 is used, a signal different from Resource index = 13 by n_oc is multiplexed and interferes, so Resource index = 1 cannot be used.

  Step 105 branches from the result of step 104 depending on whether there is an available resource index. If it exists, go to Step 106, and if not, go to Step 108.

  In step 106, an uplink control signal resource used by the terminal is selected. In step 104, when only one available resource index is found, that resource is used, and when more than one resource index is found, one of them is used as an uplink control signal resource. There is no particular rule for determining one from a plurality of candidates, and there are methods such as selecting the resource found first or selecting it randomly.

  In step 107, the uplink control signal management table of FIG. For example, when a resource with resource index = 0 is selected for the terminal with ID number 60 in step 106, the UE ID with resource index = 0 in FIG.

  In step 108, since no resource that can be allocated in step 104 was found, the allocation of the uplink control signal to the terminal is given up.

  In step 109, it is confirmed whether there is another terminal that needs to be assigned an uplink control signal. If there is still a terminal that needs to be assigned an uplink control signal, the process proceeds to step 102, and if there is no terminal, this flow is terminated.

  In this way, the use status of resources is managed by the uplink control signal management table of FIG. 2, and the uplink control signal is not assigned to a plurality of resources having the same m and n_cs but different only by n_oc. It is possible to reduce the influence of interference in the separation of the uplink control signal.

  A plurality of resources that can be allocated to the uplink control signal are prepared, and Resource index numbers are assigned in order. However, not all resource indexes are actually used. Even if resource index numbers are assigned on the premise of code division multiplexing, the method of this embodiment can avoid the influence of intersymbol interference due to multiplexing of uplink control signals. As a result, it is possible to prepare as many resource indexes as code division divisions in a small time / frequency region, and thus it is possible to use a large amount of time / frequency region for data signals.

  Here, in the uplink control signal management table of FIG. 2, a state called terminal moving speed (UE speed) may be added. The uplink control signal management table in FIG. 2 is for avoiding intersymbol interference in code division multiplexing. Therefore, when it is assumed that intersymbol interference does not occur, the uplink control signal may be multiplexed by code division. For example, when it is determined that the moving speed of the terminal is low and the influence of the Doppler effect is small, the uplink control signal of the terminal may be multiplexed with the uplink control signal of another terminal by code division. Therefore, in step 107 of FIG. 1, UE speed may be set to High when the moving speed of the terminal to which resources are allocated to the uplink control signal in Step 106 is high, and UE speed may be set to Low when the speed is low. . Further, in step 104, when the moving speed of the terminal selected in step 102 is high, it is determined that only a resource index having a resource index UE ID of None, in which m and n_cs are the same and only n_oc is different, can be used. When the moving speed of the terminal is low, it can be determined that a Resource index whose Resource ID UE ID is None or UE speed is Low can be used, where m and n_cs are the same and only n_oc is different.

  For example, when an uplink control signal is assigned to a terminal moving at a low speed, it is assumed that there are 23 resource index candidate values in step 103. The UE ID of Resource index = 23 is None. Furthermore, Resource index is 11 and 35 with the same m and n_cs but only n_oc is different, UE ID of Resource index = 11 is None, UE ID of Resource index = 35 is already assigned as 52, but UE speed is Low It is. Therefore, in step 106, the uplink control signal of the terminal can be assigned to Resource index = 23.

  In this way, by distinguishing terminals moving at low speed, it is possible to efficiently allocate resource index to terminals moving at low speed, and the uplink control signal due to lack of available resource index The probability of deferring allocation (state of step 108) can be reduced.

  In addition, in the above process, a resource index that preferentially assigns another low-speed terminal to a resource index in which m and n_cs are the same and only n_oc is different is assigned to the terminal moving at low speed in step 106. Can do. Since such a resource index is a resource index that cannot be assigned to a fast moving terminal, even if this resource index is assigned to a slow moving terminal, a resource index that can be used by a fast moving terminal The number does not decrease. From this, it is possible to assign an uplink control signal to a terminal moving at a low speed without increasing the probability of postponing the assignment of the uplink control signal of the terminal moving at a high speed (the state of step 108).

  The moving speed of the terminal can be estimated, for example, by a frequency shift that occurs in the uplink signal due to the Doppler effect, and may be managed separately from the uplink control signal management table of FIG.

  FIG. 3 is an example of a table for managing resources of uplink control signals when the present invention is applied to an LTE base station. Differences from FIG. 2 will be described below.

  M in FIG. 3 indicates the number of the PUCCH region. Here, it is assumed that the PUCCH region of PUCCH format 1 / 1a / 1b starts from m = 4, and when m = 4, only three types of n_cs = 0, 1, and 2 are used. The value of m started in the PUCCH region and the value of n_cs used in the first PUCCH region are determined by parameters included in the broadcast information. The value of deltaPUCCH-Shift is assumed to be 1. An RNTI (Radio Network Temporary Identifier) set between the base station and the terminal is used as the UE ID.

  In LTE, orthogonal code division multiplexing of uplink control signals is used in PUCCH format 1 / 1a / 1b. There are two types of uplink control information transmitted in PUCCH format 1 / 1a / 1b: SR (Scheduling Request) and HARQ-ACK (Hybrid Automatic Repeat request-ACKnowledgement).

  HARQ-ACK is an uplink control signal for notifying whether the downlink data signal has arrived correctly. The downlink data signal allocation notification is notified by a downlink control signal. The downlink control signal is assigned to a downlink control signal channel called PDCCH (Physical Downlink Control CHannel). PDCCH resources are numbered and are called CCE index (Control Channel Element index). When HARQ-ACK is transmitted by uplink control signal for downlink data signal notified by downlink control signal, Resource index of uplink control signal allocated to HARQ-ACK is uniquely determined by CCE index of downlink control signal . Accordingly, the PDCCH CCE index and the PUCCH resource index need to be managed at the same time, and therefore, the uplink control signal management table of FIG. 3 includes columns of PDCCH and PUCCH.

  Since HARQ-ACK is transmitted after reception of the downlink data signal, the PUCCH grouped in FIG. 3 is for a subframe after PDCCH, and the time difference is defined as a standard. In order to improve the PDCCH reception characteristics of the terminal, a plurality of continuous CCE indexes may be assigned to one downlink control signal. In this case, the PUCCH Resource index is the one with the smallest value among the assigned CCE indexes. Calculated on the basis.

  FIG. 3 is a table assuming TDD (Time Division Duplex). In TDD, since the number of uplink subframes may be smaller than the number of downlink subframes, HARQ-ACK corresponding to a plurality of downlink subframes may be assigned to PUCCH. Therefore, the CDC index corresponding to a plurality of subframes is included in the PDCCH field. In this example, TDD is assumed, but the present invention is not limited to TDD, and can be similarly implemented in FDD (Frequency Division Duplex).

  SR is used when a terminal requests a base station to allocate resources for uplink data communication. When establishing a connection with the terminal, the base station allocates a resource for an uplink control signal for SR in advance and notifies the terminal of the information. In FIG. 3, 11 resource indexes (0 to 10) are reserved for SR. This number is determined by parameters included in the broadcast information.

  In LTE, as shown in FIG. 9, the PUCCH is divided into two slots, and different n_oc and n_cs are used for each slot. Therefore, in FIG. 3, n_oc and n_cs are shown for each of the two slots. It is defined by the standard that m, n_oc, and n_cs in each slot are calculated from the resource index.

  Since one resource index has different sets of (n_oc, n_cs) in two slots, it is necessary to correct the search method in step 204 of FIG. There are two search methods shown below, either of which may be adopted.

  The first method is a method for avoiding intersymbol interference in all slots. The candidate value of the resource index is searched in the uplink control signal management table of FIG. 3, and the RNTI is read to check whether the resource index has already been assigned. When there is no allocation, paying attention to the first slot, search for a resource index having the same resource index, m, and n_cs but different only in n_oc, and read the RNTI. As a result, if it has already been assigned to another terminal, the candidate value of the resource index targeted here cannot be used. Next, paying attention to the second slot, a resource index having the same resource index, m, and n_cs but different only in n_oc is searched, and the RNTI is read. As a result, if it has already been assigned to another terminal, the candidate value of the resource index targeted here cannot be used. As described above, the Resource index that does not cause intersymbol interference in the uplink control signal in both the first slot and the second slot is searched and made available.

  For example, Resource index = 11 in FIG. 3 has RNTI of None, and when focusing on the first slot, only n_oc is different. Resource index = 23, RNTI of 35 is None, and focusing on the second slot, only n_oc is Since the RNTIs of different Resource indexes = 15 and 19 are None, Resource index = 11 can be used by avoiding interference in both slots. On the other hand, although RNTI is None for Resource index = 40, Resource index = 40 is not usable because RNTI of Resource index = 16, which is different only in n_oc from the first slot, has been allocated instead of None.

  The second method is a method for avoiding intersymbol interference in any one of the slots. The candidate value of the resource index is searched in the uplink control signal management table of FIG. 3, and the RNTI is read to check whether the resource index has already been assigned. When there is no allocation, paying attention to the first slot, search for a resource index having the same resource index, m, and n_cs but different only in n_oc, and read the RNTI. As a result, if no assignment is made to another terminal, the candidate value of the Resource index targeted here can be used. Next, paying attention to the second slot, a resource index having the same resource index, m, and n_cs but different only in n_oc is searched, and the RNTI is read. As a result, if no assignment is made to another terminal, the candidate value of the Resource index targeted here can be used. As described above, the Resource index that does not cause intersymbol interference in the uplink control signal can be used in at least one of the first slot and the second slot.

  In this method, when receiving PUCCH format 1 / 1a / 1b, the frequency shift due to the Doppler effect is estimated from the received signal in the slot where no intersymbol interference occurs, and the result is used to receive the slot where the intersymbol interference occurs. It is possible to perform signal correction. For example, Resource index = 40 in FIG. 3 has an RNTI of None, and paying attention to the second slot, Resource index = 36, which differs only in n_oc, and RNTI of 44 is also None, so Resource index = 40 can be used. . Focusing on the first slot, the RNTI of Resource index = 16, which differs only in n_oc, has been assigned instead of None, but there is no problem because intersymbol interference is avoided in the second slot.

  However, in the second method, when there is intersymbol interference in one slot, care must be taken so that the resource index of the interfering partner does not become unavailable. For example, Resource index = 39 in FIG. 3 is RNTI None, Resource index = 35, which differs only in n_oc focusing on the second slot, and 43 RNTI is None, so Resource index = 39 can be used . Paying attention to the first slot, the RNTI of Resource index = 27, which is different only in n_oc, has already been assigned, so intersymbol interference with Resource index = 27 remains in the first slot. However, since Resource Index = 27 pays attention to the second slot and RNTI is assigned to Resource index = 31 which differs only in n_oc, there is intersymbol interference in the second slot. That is, when Resource index = 39 is used, intersymbol interference occurs in both the first and second slots with respect to the assigned Resource index = 27, and therefore Resource index = 27 becomes unusable. Therefore, it is determined that Resource index = 31 cannot be used.

  In the first method, since intersymbol interference does not occur in all slots, reception characteristics are better than in the second method in which intersymbol interference may occur in any one slot. On the other hand, in the second method, the condition for making the Resource index available is more relaxed than in the first method. Therefore, if the second method is used, the uplink control signal allocation postponed due to the lack of available Resource index ( The probability of the state of step 108 in FIG. 1 can be reduced. The designer can select either method in consideration of this trade-off relationship.

  As described above, by configuring the uplink control signal management table, the present invention can be applied in LTE.

  FIG. 4 is a flowchart showing an embodiment of an SR allocation processing procedure.

  In step 201, an uplink control signal management table is initialized. Specifically, in the resource management table of the uplink control signal in FIG. 3, RNTI is set to None (no assignment) for all resource indexes.

  In step 202, the process waits for the establishment of a new connection with the terminal or the occurrence of a connection release event with the terminal that has established the connection.

  In step 203, the process branches according to the event generated in step 202. If the establishment of a new connection with the terminal occurs, the process proceeds to step 204. If the connection with the established terminal has been released, the process proceeds to step 209.

  In step 204, the resource index of the available uplink control signal is searched by the first or second method of the second embodiment.

  Step 205 branches from the result of step 204 depending on whether there is an available resource. If it exists, the process proceeds to step 206. If it does not exist, the process proceeds to step 208.

  In Step 206, the Resource index obtained in Step 204 is used as the resource of the SR uplink control signal used by the new connection destination terminal generated in Step 202.

  In step 207, the uplink control signal management table of FIG. 3 is updated based on the result of step 206. Thereafter, the process returns to step 202.

  In step 208, since no resources that can be allocated in step 204 are found, the allocation of the uplink control signal to the terminal is given up. Thereafter, the process returns to step 202.

  In step 209, in the uplink control signal management table of FIG. 3, the assignment of the uplink control signal of the terminal corresponding to the connection release generated in step 202 is restored. For example, the RNTI of the disconnected terminal generated in step 202 is 60, and Resource index = 0 is assigned as a resource of the Scheduling Request uplink control signal to the terminal of RNTI = 60 in the uplink control signal management table of FIG. In this case, RNTI of Resource index = 0 is returned to None. Thereafter, the process returns to step 202.

  When establishing a connection with the terminal, the base station allocates a resource for an uplink control signal for SR in advance and notifies the terminal of the information. Therefore, in step 202, the establishment of a new connection with the terminal is detected, and by searching the resource index that can be allocated in step 204, the SR uplink control signals of a plurality of terminals are arranged in the same time / frequency region. Can be avoided.

  Further, when the connection with the terminal is released, it is not necessary to allocate resources to the SR, so it is necessary to delete the allocation from the uplink control signal management table of FIG. Therefore, in step 202, the connection with the established terminal is detected, and in step 209, the uplink control signal allocation information is restored and released to reallocate resources to the terminals to be connected thereafter. be able to.

  Here, a part (Resource index 0 to 10 in the example of FIG. 3) corresponding to the SR allocation management in the uplink control signal management table of FIG. 3 is prepared in advance for a plurality of uplink subframes. In LTE, a period is set for SR allocation, and SR allocation to terminals is managed within the period. For example, when the period of 80 subframes is set, the uplink control signals for all SR transmission opportunities are managed by preparing the portion corresponding to the SR allocation management in the uplink control signal management table of FIG. can do. If the SR allocation cycle is short, for example, set to 5 subframes, an uplink control signal management table may be prepared for PUCCH during 5 subframes.

  FIG. 5 is a flowchart showing an embodiment of a downlink control signal allocation processing procedure.

  As described above, in LTE, HARQ-ACK is transmitted in addition to SR in PUCCH format 1 / 1a / 1b. When HARQ-ACK is transmitted by uplink control signal for downlink data signal notified by downlink control signal, Resource index of uplink control signal allocated to HARQ-ACK is uniquely determined by CCE index of downlink control signal . Therefore, it is necessary to manage the PUCCH resource index assignment when assigning the PDCCH CCE index.

  In step 301, the uplink control signal management table of FIG. 3 is initialized with the uplink control signal management table generated by the SR assignment obtained from the third embodiment. All the RNTIs corresponding to the PUCCH resource index to which no SR is assigned are initialized to None (no assignment), and all the RNTIs of the PDCCH are also initialized to None (no assignment).

  In step 302, one downlink control signal to be assigned is selected.

  Step 303 branches according to the type of downlink control signal to be assigned. If the downlink control signal is a downlink data signal allocation notification, the process proceeds to step 304. If the downlink control signal is an uplink data signal allocation notification, the process proceeds to step 305. If the downlink control signal is another downlink control signal, the process proceeds to step 306.

  In steps 304 to 306, a CCE index assignment process is performed for the downlink control signal according to each case. Details of the processing will be described later.

  In step 307, it is confirmed whether there is another downlink control signal that needs to be allocated. If it is still necessary to assign a downlink control signal, the process proceeds to step 302.

  FIG. 6 is a flowchart showing an embodiment of the CCE index assignment processing procedure (step 304) when the downlink control signal is a downlink data signal assignment notification.

  In step 401, a CCE index to which the downlink control signal can be assigned is searched. An assignable CCE index is searched by referring to a plurality of candidate CCE index values in the uplink control signal management table of FIG. There can be a plurality of assignable CCE indexes obtained as search results.

  Step 402 branches depending on whether there is an assignable CCE index. If it exists, the process proceeds to step 403. If it does not exist, the process proceeds to step 411.

  Step 403 branches depending on whether it is necessary to respond HARQ-ACK with PUCCH format 1a / 1b to the downlink data signal assigned by the downlink data signal assignment notification. If necessary, go to Step 405, otherwise go to Step 410.

  Normally, a downlink data signal always requires a HARQ-ACK response, and an uplink control signal of PUCCH format 1a / 1b is allocated, but this allocation may be unnecessary. For example, when a terminal to which a downlink data signal is allocated has an uplink data signal allocated simultaneously in a subframe in which HARQ-ACK is transmitted, since the HARQ-ACK is multiplexed and responded to the uplink data signal, the uplink control signal is allocated. Not necessary. In addition, when CQI (Channel Quality Information) is transmitted simultaneously in a subframe where a terminal to which a downlink data signal is allocated transmits HARQ-ACK, HARQ-ACK is returned in PUCCH format 2a / 2b, so PUCCH format 1a / There is no need to assign an uplink control signal of 1b. In the bundling mode where bundled HARQ-ACK responses to downlink data signals assigned to multiple subframes are transmitted in TDD, only HARQ-ACK for downlink data signals assigned to one subframe is used. There is no need to assign an uplink control signal for HARQ-ACK to downlink data signals assigned to other subframes.

  In step 405, the resource index of the corresponding HARQ-ACK uplink control signal is calculated for the candidate value of the downlink control signal allocation CCE index obtained in step 401. However, if the uplink control signal management table is configured as shown in FIG. 3, the Resource index corresponding to the CCE index can be obtained from the table.

  In step 406, the available resource index is searched from the candidate values of the resource index obtained in step 405. Whether or not the resource index is usable is determined using the first or second method of the second embodiment and the uplink control signal management table of FIG.

  Here, in the same way as in the first embodiment, when the moving speed of the terminal is low, it is possible to use a resource index in which m and n_cs are the same but only n_oc is different and the RNTI of the resource index is None or the UE speed is Low. Can be determined. For example, assume that there is an uplink control signal management table in FIG. 3, and when an uplink control signal is allocated to a terminal moving at a low speed, there are 12 resource index candidate values. The RNTI of Resource index = 12 is None. Focusing on the first slot, look at the RNTI of Resource index = 24, 36 where m and n_cs are the same and only n_oc is different. The RNTI of Resource index = 24 is None, and the RNTI of Resource index = 36 has been allocated, but the UE speed is Low. Therefore, it can be determined that Resource index = 12.

  Step 407 branches from the result of step 406 depending on whether there are any available resources. If it exists, the process proceeds to step 408, and if not, the process proceeds to step 411.

  In step 408, an uplink control signal resource used by the terminal is selected. In step 406, if only one available resource index is found, that resource is used, and if more than one resource index is found, one of them is used as an uplink control signal resource. There is no particular rule for determining one from a plurality of candidates, and there are methods such as selecting the resource found first or selecting it randomly. Also, a CCE index corresponding to the selected Resource index is assigned to the downlink control signal.

  In step 409, the uplink control signal management table of FIG. 3 is updated based on the result of step 408. Specifically, the terminal RNTI is set for the selected PUCCH Resource index, and the terminal RNTI is also set for the corresponding PDCCH CCE index.

  In step 410, one CCE index candidate value obtained in step 401 is selected and assigned to the downlink control signal. Since uplink control signal allocation is not necessary, there is no restriction by the uplink control signal management table of FIG. By this assignment, the RNTI of the terminal is set for the selected CCE index, thereby updating the uplink control signal management table of FIG.

  Step 411 is a process when the CCE index that can be allocated in step 401 is not found or the uplink control signal resource that can be allocated in step 406 is not found, and the downlink control corresponding to the allocation of the downlink data signal to the terminal. Give up the signal assignment.

  FIG. 7 is a flowchart showing an embodiment of the CCE index assignment processing procedure (step 305) when the downlink control signal is an uplink data signal assignment notification.

  In step 501, a CCE index to which the downlink control signal can be assigned is searched. An assignable CCE index is searched by referring to a plurality of candidate CCE index values in the uplink control signal management table of FIG. There can be a plurality of assignable CCE indexes obtained as search results.

  Step 502 branches depending on whether there is an assignable CCE index. If it exists, the process proceeds to step 503, and if it does not exist, the process proceeds to step 508.

  In step 503, one of the CCE index candidate values obtained in step 501 is selected and assigned to the downlink control signal. There is no restriction by the uplink control signal management table of FIG. By this assignment, the RNTI of the terminal is set for the selected CCE index, thereby updating the uplink control signal management table of FIG.

  In step 504, a downlink data signal is also assigned to a terminal to which an uplink data signal is assigned, and a branch is made depending on whether or not HARQ-ACK for the downlink data signal is transmitted in the same subframe as the uplink data signal. If there is such a downlink data signal assignment, the process proceeds to step 505, and if not, the process proceeds to step 506.

  In step 505, the resource index of the HARQ-ACK uplink control signal assigned to the terminal is released, and the uplink control signal management table in FIG. 3 is updated. For example, when the HARQ-ACK uplink control signal is assigned to the terminal, the RNTI for the resource index is changed to None.

  Step 506 branches depending on whether or not the SR uplink control signal is also assigned in the same subframe to the terminal to which the uplink data signal is assigned. If there is an SR uplink control signal allocation, the process proceeds to step 507, and if not, the process ends.

  In step 507, the resource index of the SR uplink control signal assigned to the terminal is released, and the uplink control signal management table in FIG. 3 is updated. For example, when the SR uplink control signal is assigned to the terminal, the RNTI of the Resource index is changed to None.

  In step 508, since the CCE index that can be allocated in step 501 is not found, the allocation of the downlink control signal corresponding to the allocation of the uplink data signal to the terminal is given up.

  FIG. 8 is a flowchart showing an embodiment of the CCE index assignment processing procedure (step 306) when the downlink control signal is a downlink control signal other than the above.

  In step 601, a CCE index to which the downlink control signal can be assigned is searched. An assignable CCE index is searched by referring to a plurality of candidate CCE index values in the uplink control signal management table of FIG. There can be a plurality of assignable CCE indexes obtained as search results.

  Step 602 branches depending on whether there is an assignable CCE index. If it exists, the process proceeds to step 603, and if it does not exist, the process proceeds to step 604.

  In step 603, one of the CCE index candidate values obtained in step 601 is selected and assigned to the downlink control signal. There is no restriction by the uplink control signal management table of FIG. By this assignment, the uplink control signal management table of FIG. 3 is updated by setting a value (for example, 0) indicating that the assignment has already been made to the selected CCE index in RNTI.

  In step 604, since the CCE index that can be allocated in step 601 is not found, the allocation of the downlink control signal to the terminal is given up.

  As described above, by managing the resource usage status in the uplink control signal management table of FIG. 3 and assigning the CCE index of the downlink control signal and the resource index of the uplink control signal, the PUCCH region and the cyclic shift are the same, but only the signs are different. By preventing uplink control signals from being assigned to a plurality of resources, it is possible to reduce the influence of interference in the separation of uplink control signals multiplexed with codes.

  When the uplink control signal is managed in the uplink control signal management table of FIG. 3, a state called terminal moving speed (UE speed) may be added similarly to the method described in the first embodiment. This also applies to initialization of the uplink control signal management table in step 301, and the state of the terminal moving speed can be set for the SR resource index. As a result, it is possible to code division multiplex the HARQ-ACK uplink control signal of a terminal having a low moving speed and the SR uplink control signal of a terminal having a low moving speed using a resource index in which m and n_cs are equal.

  Other downlink control signals at the branch of step 303 include, for example, System Information (broadcast information), Paging, and downlink data allocation notification of multicast data. HARQ-ACK is not transmitted from the terminal for these data. Also, control signals without downlink data transmission are included in other downlink control signals. Also in the downlink data signal of LTE Random Access Response, HARQ-ACK is not transmitted from the terminal. However, since Random Access Response includes uplink signal allocation information in the data part, when applying this embodiment in a subframe in which the uplink signal is transmitted, it is processed as if there is an uplink data signal allocation notification. It ’s fine. The LTE TDD scheme has a Bundling mode as a HARQ-ACK transmission scheme. When the number of subframes assigned to uplink signals in TDD is smaller than the number of subframes assigned to downlink signals, when downlink data signals are assigned to the same terminal in consecutive subframes, only one HARQ-ACK uplink control signal is multiplexed. Sent. The resource index of this HARQ-ACK uplink control signal is only that corresponding to the CCE index of the downlink control signal of the subframe in which downlink data is first transmitted. Therefore, no HARQ-ACK response is required for downlink control signals assigned to other downlink data signals. In step 303, these downlink control signals may be classified as other downlink control signals.

  In step 410, a CCE index corresponding to a resource index that is unavailable or can be used only by a low-speed terminal may be preferentially selected with reference to the uplink control signal management table. Since only a finite number of CCE indexes are prepared, it is conceivable that the CCE index is insufficient when it is necessary to assign downlink control signals to a plurality of terminals. Therefore, by preferentially assigning a CCE index that cannot be used by a terminal that needs to transmit a HARQ-ACK uplink control signal in step 410, a CCE index that can be used by a terminal that needs to transmit a HARQ-ACK uplink control signal is set. Secure and reduce the possibility of CCE index shortage.

  In step 503, the CCE index of the downlink control signal corresponding to the allocation of the uplink data signal is determined. In LTE, when uplink data signals are allocated, HARQ-ACK is multiplexed in the uplink data signal area, and uplink control signals are not used. Therefore, consider the limitation by the uplink control signal management table when selecting the CCE index. do not have to. Updating of the uplink control signal management table by this allocation is only required to update the allocation information of the PDCCH CCE index. Here, referring to the uplink control signal management table, a CCE index corresponding to a resource index that is unavailable or available only to low-speed terminals may be preferentially selected. Since only a finite number of CCE indexes are prepared, it is conceivable that the CCE index is insufficient when it is necessary to assign downlink control signals to a plurality of terminals. Therefore, the CCE index that cannot be used by the terminal that needs to transmit the HARQ-ACK uplink control signal is preferentially assigned in step 503, so that the CCE index that can be used by the terminal that needs to transmit the HARQ-ACK uplink control signal is set. Secure and reduce the possibility of CCE index shortage.

  In step 504, a downlink data signal is also allocated to a terminal to which an uplink data signal is allocated, and it is determined whether HARQ-ACK for the downlink data signal is transmitted in the same subframe as the uplink data signal. This is because, in LTE, when an uplink data signal is allocated, HARQ-ACK is multiplexed in the area of the uplink data signal and the uplink control signal is not used. Therefore, in step 505, the RNTI of the resource index assigned to the HARQ-ACK uplink control signal may be returned to None. Since only a finite number of CCE indexes are prepared, it is conceivable that the CCE index is insufficient when it is necessary to assign downlink control signals to a plurality of terminals. Therefore, the operation of returning the allocation of the HARQ-ACK uplink control signal to None can increase the available CCE index and reduce the possibility that the CCE index is insufficient.

  In step 506, it is determined whether or not the SR uplink control signal is also assigned in the same subframe to the terminal to which the uplink data signal is assigned. This is because in the LTE, the SR uplink control signal is not transmitted when there is an uplink data signal allocation. Therefore, in step 507, the RNTI of the resource index assigned to the SR uplink control signal may be returned to None. Since only a finite number of CCE indexes are prepared, it is conceivable that the CCE index is insufficient when it is necessary to assign downlink control signals to a plurality of terminals. Therefore, the operation of returning the SR uplink control signal assignment to None can increase the available CCE index and reduce the possibility that the CCE index is insufficient.

  In step 603, since the CCE index of the downlink control signal not accompanied by the HARQ-ACK uplink control signal is selected, there is no need to consider the limitation by the uplink control signal management table, and the uplink control signal management table by this allocation is not necessary. There is no need to update. Updating of the uplink control signal management table by this allocation is only required to update the allocation information of the PDCCH CCE index. Here, referring to the uplink control signal management table, a CCE index corresponding to a resource index that is unavailable or available only to low-speed terminals may be preferentially selected. Since only a finite number of CCE indexes are prepared, it is conceivable that the CCE index is insufficient when it is necessary to assign downlink control signals to a plurality of terminals. Therefore, a CCE index that cannot be used by a terminal that needs to transmit a HARQ-ACK uplink control signal is preferentially assigned in step 603, so that a CCE index that can be used by a terminal that needs to transmit a HARQ-ACK uplink control signal is set. Secure and reduce the possibility of CCE index shortage.

  In LTE, for example, when operating with a 20 MHz bandwidth, a maximum of 88 CCE indexes are prepared per subframe. Since the uplink control signal is multiplexed with three codes, if the CCE index is randomly assigned to two downlink control signals accompanied by the HARQ-ACK uplink control signal, the same Frequency index and Cyclic with a probability of 2/87. Code division multiplexing is performed on the shift index. That is, the probability is 2.3%. For example, if the Doppler effect occurs in communication with a high-speed mobile terminal, there is a possibility that an error occurs in reception of the uplink control signal with a probability of 2.3%. According to the present embodiment, this probability can be reduced to 1% or less, for example.

  FIG. 12 is a diagram showing the configuration of the base station of the present invention.

  A scheduler 700 is connected to the core network side to exchange data, and communicates with a terminal via a PUCCH processing unit 701, a user data receiving unit 702, a user data transmitting unit 703, and a PDCCH generating unit 704.

  The scheduler 700 includes a control unit 710, a user data scheduler 711, an uplink control signal management table holding unit 712, a terminal moving speed holding unit 713, and a control signal scheduler 714. The control unit 710 controls communication between the scheduler 700 and other blocks. The user data scheduler 711 schedules resource allocation for user data communication between the base station and the terminal. The schedule result is notified to the control signal scheduler 714. The uplink control signal management table holding unit 712 holds, for example, the uplink control signal management table of FIG. The terminal moving speed holding unit 713 holds the moving speed of each terminal. Typically, in the uplink control signal management table of FIG. 3, information on whether UE speed is set to Low or High is held. The control signal scheduler 714 assigns the PDCCH CCE index and the PUCCH resource index as shown in the third and fourth embodiments, for example. Information on the downlink control signal that needs to be allocated is notified from the user data scheduler 711. Further, a control information signal or the like not related to the user data is notified from the control unit 710. The control signal allocation result by the control signal scheduler 714 is notified to each of 701 to 704.

  A PUCCH processing unit 701 receives an uplink control signal in accordance with an instruction from the scheduler 700. The PUCCH processing unit 701 includes a slot distribution unit 720, a frequency shift estimation unit 721, an uplink control signal demodulation unit 722, a slot combination unit 723, and an uplink control signal decoding unit 724.

  Slot distribution section 720 forms a PUCCH region from the signal received from 705 and distributes it to two slots. Frequency shift estimation unit 721 estimates the frequency shift using the signal received from slot distribution unit 720. However, in some slots, the uplink control signal is code division multiplexed, and it may be difficult to estimate the frequency shift. Therefore, the control signal scheduler 714 notifies the slot where the control signal is not code division multiplexed, and the frequency shift estimation unit 721 estimates the frequency shift using the signal of an appropriate slot based on the information. Based on the frequency shift estimated by the frequency shift estimation unit 721, the uplink control signal demodulation unit 722 compensates and demodulates the frequency shift occurring in the received signal. The slot combining unit 723 combines the signals of the two slots demodulated by the uplink control signal demodulating unit 722. However, since the uplink control signal is code division multiplexed depending on the slot, the quality of the demodulated signal differs depending on the slot. Therefore, the control signal scheduler 714 notifies the slot where the control signal is not code division multiplexed, and the uplink control signal demodulator 722 weights each slot based on the information and synthesizes the signal. Uplink control signal decoding section 724 decodes the signal obtained by slot combining section 723 and notifies scheduler 700 of the result.

  A user data receiving unit 702 receives uplink user data according to an instruction from the scheduler 700. Based on the allocation information notified from the control signal scheduler 714, the user data is restored from the signal received from 705 and notified to the scheduler 700.

  A user data transmission unit 703 transmits downlink user data in accordance with an instruction from the scheduler 700. Based on the allocation information notified from the control signal scheduler 714, the user data received from the scheduler 700 is converted into a radio signal and notified to 706.

  A PDCCH generation unit 704 generates a downlink control signal according to instructions from the scheduler 700 and the control signal scheduler 714 and notifies the 706 of the downlink control signal.

  A received signal distribution unit 705 divides the signal received from 707 into an uplink control signal and uplink user data, and passes them to the PUCCH processing unit 701 and the user data receiving unit 702, respectively.

  A transmission signal combining unit 706 combines signals received from the user data transmission unit 703 and the PDCCH processing unit 704 to generate a radio signal and passes it to 707.

  Reference numeral 707 denotes an analog front end, which converts an analog signal received by the antenna 708 into a digital signal and passes it to the reception signal distribution unit 705, and converts a digital signal received from the transmission signal coupling unit 706 into an analog signal to convert the antenna to the antenna. Pass to 708.

  By configuring the base station as described above, it is possible to implement resource allocation to the control signal of the present invention.

  The scheduler configuration described above can be configured by software that operates on a processing device using a computer including a processing device and a storage device. The computer may include an input device, an output device, and the like. In addition, functions equivalent to those configured by software can be realized by hardware such as FPGA (Field Programmable Gate Array) and ASIC (Application Specific Integrated Circuit). Arbitrary portions of the input device, the output device, the processing device, and the storage device may be configured by other devices connected by a wired or wireless network. The idea of the invention is equivalent and unchanged.

  The present invention is not limited to the embodiments described above, and includes various modifications. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

101-604 Step 700 in the flowchart Scheduler 701 PUCCH processing unit 702 User data receiving unit 703 User data transmitting unit 704 PDCCH processing unit 705 Received signal distribution unit 706 Transmission signal combining unit 707 Analog front end 708 Antenna 710 Control unit 711 User data scheduler 712 Uplink control signal management table holding section 713 Terminal moving speed holding section 714 Control signal scheduler 720 Slot distribution section 721 Frequency shift estimation section 722 Uplink control signal demodulation section 723 Slot combination section 724 Uplink control signal decoding section

Claims (15)

An uplink control signal management table for managing resources allocated to uplink control signals;
When allocating resources to the new uplink control signal, select an allocated resource and a resource that is not code division multiplexed from the uplink control signal management table, and allocate the resource to the new uplink control signal.
A radio communication base station that updates the uplink control signal management table with information on resources allocated to the new uplink control signal. The radio communication base station according to claim 1,
Distinguishes the assignment of the uplink control signal to a terminal with a slow moving speed and the assignment of the uplink control signal to a terminal with a fast moving speed, and manages them in the uplink control signal management table,
Allowing uplink control signals between the terminals with low moving speed to be code division multiplexed;
A radio communication base station that assigns an uplink control signal to an uplink control signal of a terminal having a high moving speed so that an uplink control signal of another terminal is not code division multiplexed. The radio communication base station according to claim 1,
The uplink control signal is a radio communication base station including an SR uplink control signal. A radio communication base station according to claim 3,
The uplink control signal includes a HARQ-ACK uplink control signal,
When assigning the HARQ-ACK uplink control signal, the uplink control signal management table is initialized by the SR uplink control signal assignment,
A radio communication base station that avoids code division multiplexing of the SR uplink control signal and the HARQ-ACK uplink control signal with the SR uplink control signal or HARQ-ACK uplink control signal of another terminal. The wireless communication base station according to claim 4, wherein
The resource of the HARQ-ACK uplink control signal is determined by an allocation index of the downlink control signal,
A radio communication base station that avoids code division multiplexing of the uplink control signal by selecting an allocation index of the downlink control signal so that a plurality of the uplink control signals avoid code division multiplexing. A radio communication control method for allocating uplink signal resources to a base station to a plurality of terminals,
The uplink signal resource is multiplexed and allocated by any one of frequency, orthogonal code, and cyclic shift,
The multiplexing allows the use of a plurality of the orthogonal codes for one cyclic shift,
A radio communication control method for performing control so that resources different only in the orthogonal code are not simultaneously assigned in at least a part of communication at the time of assignment. The wireless communication control method according to claim 6,
A radio communication control method for performing control so that resources different only in the orthogonal code are not simultaneously assigned in all communications. The wireless communication control method according to claim 6,
The base station
Manages an uplink control signal management table that manages a set of IDs for identifying downlink signal resources from the base station to the terminal, the set of frequencies, orthogonal codes, and cyclic shifts, and IDs of terminals associated with the set And
When allocating the downlink signal resource, add the ID of the terminal to allocate the resource to the set,
A radio communication control method for deleting an ID of a terminal added to the set when releasing resources from the terminal. The wireless communication control method according to claim 6,
The base station
Detecting the moving speed of the terminal trying to allocate uplink signal resources,
A radio communication control method for performing control so that only resources having different orthogonal codes are not allocated at the time of allocation only when a moving speed is equal to or greater than a predetermined threshold. A wireless communication base station that communicates with a plurality of terminals,
A scheduler for allocating uplink signal resources from the plurality of terminals to the base station to the plurality of terminals;
The scheduler
The uplink signal resources are multiplexed and allocated according to any one of frequency, orthogonal code, and cyclic shift,
The multiplexing allows the use of a plurality of the orthogonal codes for one cyclic shift,
A radio communication base station that performs control so that resources different only in the orthogonal code are not allocated in at least a part of communication at the time of the allocation. The wireless communication base station according to claim 10, wherein
The scheduler
Refer to a table corresponding to a set of frequency, orthogonal code, and cyclic shift for one resource index,
A radio communication base station that allocates one terminal to the one Resource index. The wireless communication base station according to claim 10, wherein
The scheduler
Refer to the table corresponding to the set of frequency, orthogonal code, cyclic shift, and CCE index of the downlink control signal for one Resource index,
A radio communication base station that allocates one terminal to the one Resource index. The wireless communication base station according to claim 10, wherein
The scheduler
Refer to a table corresponding to a set of frequency, orthogonal code, and cyclic shift for one resource index,
Assign one terminal to the one Resource index,
A wireless communication base station that refers to speed information of the plurality of terminals at the time of assignment. The wireless communication base station according to claim 10, wherein
The uplink signal is PUCCH, which is an LTE-compliant uplink control signal channel,
The PUCCH is multiplexed with PUCCH regions having different frequencies or timings, 12 cyclic shifts, and 3 orthogonal code divisions,
A radio communication base station to which the uplink signal resource is allocated under the condition of the LTE-compliant parameter deltaPUCCH-Shift = 1 or 2. The radio communication base station according to claim 14,
A radio communication base station that also allocates resources of the uplink signal when the type of downlink signal to be allocated is specific at the time of allocation of PDCCH, which is an LTE-compliant downlink signal channel.

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