JP2011249915A - Radio communication device and radio communication method - Google Patents

Abstract

Even if the transmission timing of information to be transmitted with priority over a subframe including many systematic bits (such as a subframe of RV = 0 in the initial transmission of SI) overlaps, The present invention provides a wireless communication apparatus and a wireless communication method capable of promptly transmitting systematic bits used for decoding to a receiving side.
An SI transmission method determining unit 102 changes RV to 0 when RV is other than 0 in the initial transmission of SI and the DCI format is 1A. Also, if the RV is other than 0 in the initial transmission of SI and the DCI format is 1C, the SI transmission method determination unit 102 changes the DCI format from 1C to 1A if there is a predetermined amount of PDCCH resources. And RV is changed to 0.
[Selection] Figure 3

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method.

  In LTE (Long Term Evolution), which is one of the next generation communication standards, BCH (Broadcast Channel) is classified into MIB (Master Information Block) and SIB (System Information Block), and transmitted on different channels.

  The MIB is transmitted by PBCH (Physical Broadcast Channel), information on downlink cell bandwidth, information on PHICH (Physical Hybrid ARQ Indicator Channel) configuration of a cell, system frame number (hereinafter referred to as “SFN (System Frame Number)”). Information).

  Moreover, SIB is transmitted by PDSCH (Physical Downlink Shard Channel), and there are 11 types (type 1 to 11). The transmission of SIB information using DLSCH (Down Link Shared Channel) is called D-BCH (Dynamic BCH). Specifically, SIB1 (SIB type1) is information related to whether or not a terminal is allowed to belong to a cell, and SIB2 is an uplink cell bandwidth, a random access parameter, uplink power control. Information about SIB3 is information related to cell reselection, and SIB4 to 8 are information related to neighboring cells. An SI message (SI message) is composed of one or a plurality of SIBs among the SIBs 2 to 11. Since the transmission timings of SIB1 and SI are different and the UE (User Equipment) does not receive them simultaneously, only one of SIB1 and SI is received at a certain timing. In addition, since SIB is transmitted by PDSCH, a turbo code is applied to channel coding.

  Rate matching (Rate Matching) is performed on a circular buffer (CB) basis, and a transmission start position is determined by a redundancy version (RV). In the circular buffer, a systematic bit is stored at the head, and then a parity bit is stored. The RV is repeated as 0, 2, 3, 1 every subframe from the transmission start timing, and data for the physical data size that can be transmitted from the head of the designated RV is extracted from the circular buffer.

  PDSCH decoding requires information such as TBS (Transport Block Size) obtained from RB allocation (Resource Block assignment) and MCS (Modulation and Coding Scheme), and also decodes PDCCH (Physical Downlink Control Channel). There must be.

  Also, in order to receive channels such as D-BCH, DLSCH, and PCH, control information called DCI (Downlink Control Information) is required. For downlink, DCI 1, 1A, 1B, 1C, 1D, 2, 2A formats are prepared. Which format is used is determined by the RNTI to be transmitted and the transmission mode (SISO, MIMO, etc.). The However, when the D-BCH is transmitted, the DCI format is specified to be transmitted in either 1A or 1C. In DCI format 1A, information such as RB allocation, MCS index, HARQ NDI (Hybrid-ARQ New Data Indicator), RV, and TPC (Transmit Power Control) is transmitted. In DCI format 1C, RB allocation and TBS index are transmitted. . Note that the number of bits required for transmission is smaller in the DCI format 1C than in the DCI format 1A.

  Non-Patent Document 1 defines the transmission timing of SIB1 and SI as follows. That is, the transmission timing of SIB1 is a frame satisfying SFN mod 2 and the # 5 subframe, and the transmission timing of SI is a frame satisfying SFN mod T = floor {(n−1) * w / 10}. Here, T is an SI period (SI Periodicity), w is an SI window length, and n is an SI number. The subframe number at the start of reception is {(n−1) * w} mod 10.

  Further, Non-Patent Document 2 discloses that when the transmission timings of SIB1 and SI overlap, SIB1 is transmitted and SI is not transmitted. FIG. 1 shows a state in which the technique of Non-Patent Document 2 is combined with the technique of Non-Patent Document 1 described above. In Non-Patent Document 2, the subframes of a multicast and broadcast single frequency network (hereinafter referred to as “MBSFN (Multicast and Broadcast Single Frequency Network)”) are # 1, 2, 3, 6, 7, and 8. , It is disclosed that the transmission is prioritized over SI.

3GPP TS36.321 V8.6.0, “MAC protocol specification” 3GPP TS36.331 V8.6.0, “RRC Protocol specification”

  However, in the technique disclosed in Non-Patent Document 2, since SIB1 and MBSFN are transmitted with priority over SI transmission, as shown in FIG. (In FIG. 2, the case of RV = 2 is shown). Depending on the size of the physical data to be transmitted, as shown in FIG. 2B, a subframe with an RV of 0 may include many systematic bits. In this case, a large number of systematic bits may not be transmitted. When many systematic bits are lost, there is a problem that error correction capability by turbo decoding cannot be expected and SI cannot be decoded.

  An object of the present invention is when a transmission timing of information to be transmitted with priority over a subframe including many systematic bits (such as a subframe of RV = 0 in the initial transmission of SI) is overlapped. Even if it exists, it is providing the radio | wireless communication apparatus and radio | wireless communication method which can transmit the systematic bit used for a decoding immediately to a receiving side.

  The wireless communication apparatus of the present invention is a wireless communication apparatus that transmits data composed of systematic bits and parity bits in a predetermined format using a plurality of subframes, wherein the plurality of subframes It is determined whether a timing at which a predetermined subframe including the systematic bit is transmitted in a frame overlaps with a timing at which a subframe of other information to be transmitted is given priority over the data. The timing overlaps, and the format is a first format that can indicate which part of the data is included in the transmitted subframe. Data transmission method determining means for changing a subframe to be transmitted next to the subframe to the predetermined subframe; A configuration that includes.

  The wireless communication method of the present invention is a wireless communication apparatus that transmits data composed of systematic bits and parity bits in a predetermined format using a plurality of subframes. It is determined whether a timing at which a predetermined subframe including the systematic bit is transmitted in a frame overlaps with a timing at which a subframe of other information to be transmitted is given priority over the data. The timing overlaps, and the format is a first format that can indicate which portion of the data is included in the transmitted subframe. And a step of changing a subframe to be transmitted next to the frame to the predetermined subframe.

  According to the present invention, when the transmission timing of information to be transmitted with priority over a subframe including many systematic bits (such as a subframe of RV = 0 in the initial transmission of SI) is duplicated, Even so, the systematic bits used for decoding can be transmitted immediately to the receiving side.

The figure which shows a mode that the technique of this nonpatent literature 2 was combined with the technique of nonpatent literature 1. The figure which shows the subject in the technique of a nonpatent literature 2 indication 1 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 1 of the present invention. FIG. 3 is a flowchart showing an SI transmission procedure in the SI transmission method determination unit shown in FIG. FIG. 2 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 2 of the present invention. Block diagram showing the configuration of a wireless communication apparatus according to Embodiment 3 of the present invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in the embodiment, configurations having the same functions are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
FIG. 3 is a block diagram showing a configuration of radio communication apparatus 100 according to Embodiment 1 of the present invention. Hereinafter, the configuration of the wireless communication apparatus 100 will be described with reference to FIG.

  The SI initial transmission retransmission determination unit 101 acquires the SI period, SI window length, SFN, and subframe number, and obtains the SFN and subframe number to be transmitted for each SI from the acquired SI period and SI window length. Further, the SFN 1 SFN and subframe number are obtained. Also, the number of SI transmissions is determined from the current SFN and subframe number. However, when SIB1 is transmitted, the number of SI transmissions is not increased. SI initial transmission retransmission determination section 101 determines SI initial transmission if the number of transmissions is 0, and determines SI retransmission if the number of transmissions is 1 or more. Information about whether SI is initially transmitted or retransmitted is output to SI transmission method determining section 102.

  SI transmission method determination section 102 acquires RV, RB allocation information, and DCI format, and outputs a resource size change request to PDCCH resource control section 103. SI transmission method determining section 102 acquires whether or not the resource size can be changed from PDCCH resource control section 103. Also, a resource size change request is output to the PDSCH resource control unit 104, whether or not the resource size is changed, and RV, RB allocation information, and a DCI format are output. Specifically, it is as follows.

  SI transmission method determination section 102 outputs the received RV, RB allocation information, and DCI format if RV = 0 in the initial transmission. If RV = 0 is not satisfied, the DCI format is confirmed. If 1A, RV = 0, RB allocation information, and the acquired value are output as the DCI format.

  On the other hand, when the DCI format is 1C, RV itself is not transmitted, so that it is not possible to force RV = 0 as in the case where the DCI format is 1A. Therefore, when the DCI format is 1C, the DCI format itself is changed to 1A. However, as described above, since the DCI format 1A requires a larger number of bits than the DCI format 1C, the format may not be changed due to resource size. Therefore, when the DCI format is 1C, the SI transmission method determination unit 102 outputs a resource size change request to the PDCCH resource control unit 103. When the PDCCH resource control unit 103 notifies that the resource size can be changed, the SI transmission method determination unit 102 outputs the DCI format as 1A and RV = 0, and outputs the received value as the RB allocation information. On the other hand, when notified from the PDCCH resource control unit 103 that the resource size cannot be changed, the SI transmission method determination unit 102 obtains a transmission physical data size from the RB allocation information and obtains a systematic bit that can be transmitted using RV.

  When the systematic bits that can be transmitted satisfy a certain ratio, the received RV, RB allocation information, and DCI format are output. On the other hand, if the systematic bits that can be transmitted do not satisfy a certain ratio, a resource size change request is output to the PDSCH resource control unit 104, and whether it is possible or not is acquired.

  When the resource size can be changed, the number of RB allocations is increased until the systematic bits become a certain ratio. On the other hand, if the resource size cannot be changed, the process ends, and the current RB allocation and the received RV and DCI formats are output.

  The PDCCH resource control unit 103 and the PDSCH resource control unit 104 output whether or not the resource size change request from the SI transmission method determination unit 102 is acceptable. This indicates general resource control. That is, if there is a margin in the resource and the resource size can be changed, the SI transmission method determining unit 102 is notified that the resource size can be changed, and if there is no margin in the resource, the resource size cannot be changed. To the SI transmission method determination unit 102.

  Next, the SI transmission procedure in SI transmission method determination section 102 shown in FIG. 3 will be described with reference to FIG. In FIG. 4, in step (hereinafter abbreviated as “ST”) 201, the number of subframes that have elapsed from the SI transmission start timing is obtained, and RV is determined. Also, the number of RB allocations (the number of RB assignments) is determined.

  In ST202, it is determined whether SI is the initial transmission and RV is 0 or not. If this condition is satisfied, the process proceeds to ST203, and if this condition is not satisfied, the SI transmission process is terminated. Here, the determination of the initial transmission of SI means whether SI has been transmitted without being affected by SIB1 or MBSFN from the SI transmission start timing.

  In ST203, it is determined whether or not the DCI format to be transmitted is 1A. If the DCI format is 1A, the process proceeds to ST204, SI is transmitted with RV = 0, and the process ends. On the other hand, if the DCI format is other than 1A, that is, 1C, the process proceeds to ST205.

  In ST205, it is determined whether or not there is a free PDCCH resource. If there is a free space, the process proceeds to ST206, the SI is set with the DCI format of 1A and RV = 0, and the process ends. On the other hand, if there is no available resource, the process proceeds to ST207.

  In ST207, based on the RV obtained in ST201, it is determined whether the transmission of systematic bits is 80% or more. If it is 80% or more, the SI transmission process is terminated, and if it is less than 80%, the process proceeds to ST208. Here, the transmission of systematic bits is 80%, but the present invention is not limited to this, and an arbitrary value can be set.

  In ST208, it is determined whether or not there is a vacancy in the PDSCH resource. If there is a vacancy, the process proceeds to ST209, the number of RB allocations is increased, and the process returns to ST207. If there is no space in the PDSCH resource, the SI transmission process is terminated.

  Note that the initial transmission SI with less than 80% systematic bits is processed on the receiving side from LLR (Log Likelihood Ratio) derivation, descrambling, derate matching, and HARQ IR buffer storage. Is not done. CRC (Cyclic Redundancy Check) determination is determined as NACK.

  Also, scheduling is performed so that MBSFN is not transmitted in the subframe in which D-BCH is transmitted for the first time. Also, the UE is not assigned to SI that cannot transmit RV = 0 by SIB1.

  As described above, according to the first embodiment, when RV is not 0 in the initial transmission of SI, if DCI format is 1A, RV is changed to 0, and if DCI format is 1C, PDCCH resources are assigned. By changing the DCI format to 1A on condition that there is a predetermined amount of free space and changing RV to 0, a sufficient amount of systematic bits can be transmitted in the initial transmission of SI. UEs can decode the SI.

  When the DCI format is 1C and the DCI format cannot be changed, control is performed so that a sufficient amount of systematic bits can be transmitted by increasing the number of RB allocations.

  The outline of the present embodiment is as follows. In the LTE standard, subframes containing a lot of systematic bits (for example, subframes with SI RV = 0) out of data sent using a plurality of subframes (in the above, equivalent to SI) due to restrictions on the standards. ), It may be necessary to transmit other information (SIB) with a higher priority at the same timing. Therefore, in such a case, control is performed such that high priority information (SIB) is transmitted and this subframe is not transmitted.

  However, when a subframe including many systematic bits is not transmitted, the systematic bits used for decoding are insufficient, so that decoding becomes difficult until the second and subsequent transmissions. Therefore, in this embodiment, the following measures are taken.

  First, consider the case where the DCI format is 1A. When the DCI format is 1A, transmission is performed by forcibly changing the next subframe of a subframe including many systematic bits (the number of systematic bits is small) to a subframe including many systematic bits. This allows many systematic bits to be transmitted instead of sacrificing the next subframe. Note that the DCI format 1A is a format in which RV indicating the transmission start position can be notified. Therefore, even if the subframe to be transmitted is forcibly switched on the transmission side, it is not mistaken which subframe is transmitted on the reception side.

  Next, consider the case where the DCI format is 1C. In the DCI format 1C, RV information is not notified. Therefore, forcibly switching the subframe as in the case of the DCI format 1A causes erroneous recognition of the subframe transmitted on the receiving side. Therefore, after changing the DCI format to 1A, the same processing as 1A is performed. However, since the number of bits required for the DCI format 1C is smaller than that of the DCI format 1A, there is a possibility that resources may be insufficient even if the DCI format is simply switched to 1A. In such a case, the format remains 1C, and the systematic bits are increased so that the information of the remaining subframes can be decoded even if there are no subframes containing many systematic bits.

(Embodiment 2)
FIG. 5 is a block diagram showing a configuration of radio communication apparatus 120 according to Embodiment 2 of the present invention. Hereinafter, the configuration of the wireless communication apparatus 120 will be described with reference to FIG. However, FIG. 5 differs from FIG. 3 in that the MBSFN transmission timing determination unit 122 is added and the SI initial transmission retransmission determination unit 101 is changed to the SI initial transmission retransmission determination unit 121.

  SI initial transmission retransmission determination section 121 obtains the SFN and subframe number for which RV = 0 for each SI, and outputs it to MBSFN transmission timing determination section 122.

  The MBSFN transmission timing determination unit 122 acquires the SFN and subframe number for which RV = 0 for each SI, and outputs the MBSFN transmission subframe number. The MBSFN transmission timing determining unit 122 checks whether or not the subframe number for which RV = 0 for each SI matches the subframe number that can be transmitted by the MBSFN, and if it matches, the subframe is not subject to MBSFN transmission. Subframe. That is, no MBSFN subframe is assigned to this subframe. On the other hand, if they do not match, this subframe is set as an MBSFN transmission target subframe.

  As described above, according to the second embodiment, when the subframe number where RV = 0 for each SI matches the subframe number that can be transmitted by MBSFN, the MBSFN subframe is not allocated to this subframe. Therefore, it is possible to avoid giving priority to MBSFN over SI.

  The outline of the present embodiment is as follows. When performing so-called multicast communication or broadcast communication such as MBSFN transmission, it is required to send the same information to all users at the same time, and the transmission timing cannot be delayed only for a certain user. Therefore, if this timing overlaps with the transmission timing of a subframe including many systematic bits (for example, a subframe in which RV = 0 of SI), multicast communication has priority over transmission of the subframe. Therefore, as in the first embodiment, there is a problem that SI decoding is delayed.

  Here, in multicast communication, timing restrictions are not as severe as in the SIB described in the first embodiment. Therefore, in this embodiment, this problem is solved by shifting the timing of multicast communication.

(Embodiment 3)
FIG. 6 is a block diagram showing a configuration of radio communication apparatus 130 according to Embodiment 3 of the present invention. Hereinafter, the configuration of the wireless communication apparatus 130 will be described with reference to FIG. However, FIG. 6 differs from FIG. 3 in that the SIB1 information determination unit 132 is added and the SI initial transmission retransmission determination unit 101 is changed to the SI initial transmission retransmission determination unit 131.

  SI initial transmission retransmission determination section 131 obtains the SFN and subframe number for which RV = 0 for each SI, and outputs it to SIB1 information determination section 132.

  The SIB1 information determination unit 132 acquires the SFN and subframe number for which RV = 0 for each SI from the SI initial transmission retransmission determination unit 131, and outputs the SIB1 information. The SIB1 information determination unit 132 determines whether or not there is no transmission of RV = 0 by SIB1 for each SI, and when there is no transmission of RV = 0, performs setting to exclude the SI from decoding targets in the UE, If transmission of = 0 does not disappear, the SI is set to be a decoding target in the UE.

  As described above, according to the third embodiment, when SI RV = 0 is not transmitted by SIB1, by excluding this SI from the decoding target in the UE, the UE has a low possibility of being decoded. There is no need for decoding, and wasteful processing can be reduced.

  The outline of the present embodiment is as follows. When a subframe including many systematic bits (for example, a subframe where RV = 0 of SI) cannot be received, there is a high possibility that the system will fail even if decoding is attempted by the receiving device because the systematic bits are insufficient. Therefore, in this embodiment, if it is known that transmission of such a subframe is disturbed by other data to be transmitted with priority, the reception apparatus is instructed not to perform decoding. Thereby, useless processing in the receiving apparatus can be reduced.

  In the first to third embodiments, the case where the transmission timing of “initial transmission and subframe of RV0” overlaps with the transmission timing of other information has been studied. However, the present invention is not limited to this. Absent.

  For example, the processing of the first to third embodiments may be performed on a subframe that is not “initial transmission”. The reason why the “initial transmission” subframe is studied in the first to third embodiments is that the SIB may take resources at the timing of the initial transmission of SI in the LTE standard. Therefore, when resources are deprived at other timings, the above-described processes of the first to third embodiments may be performed on such subframes. However, even if the second and subsequent transmissions are obstructed, there is a high possibility that a predetermined subframe has already been received in the initial transmission, so the above-described processes of the first to third embodiments are applied to the case of “initial transmission”. The effect that is obtained is great.

  The reason why the subframe of “RV0” is targeted is that SI has a structure in which a systematic bit is followed by a parity bit in the LTE standard, and the first subframe includes the most systematic bits. . Therefore, if the other subframe includes more systematic bits, the processes of the first to third embodiments may be performed on the subframe. Moreover, you may perform said 1st-3rd process for the sub-frame containing fewer systematic bits. However, the effect obtained by targeting the subframe containing the most systematic bits is great.

  As mentioned above, although Embodiment 1-3 was demonstrated based on the LTE specification, it is not restricted to this. For example, the ideas of Embodiments 1 to 3 may be applied to channels other than D-BCH, or may be applied to information other than System Information. In the first to third embodiments, information (RV) indicating a transmission start position is used as information to be notified when a transmitted subframe is switched. However, the present invention is not limited to this. Absent. Other information may be used as long as the information indicating which part of the data is the transmitted subframe can be used. That is, the description in Embodiments 1 to 3 described above is for the LTE standard, but is not limited thereto. In the future, when a standard similar to or similar to the LTE standard appears in the future, the idea of the present invention can be applied to those standards.

  The radio communication apparatus and radio communication method according to the present invention can be applied to, for example, a mobile communication system.

101, 121, 131 SI initial transmission retransmission determination unit 102 SI transmission method determination unit 103 PDCCH resource control unit 104 PDSCH resource control unit 122 MBSFN transmission timing determination unit 132 SIB1 information determination unit

Claims (9)

A wireless communication device for transmitting data composed of systematic bits and parity bits in a predetermined format using a plurality of subframes,
Whether the timing at which a predetermined subframe including the systematic bit among the plurality of subframes is transmitted overlaps with the timing at which a subframe of other information to be transmitted with priority over the data is transmitted Determining means for determining whether or not;
If the timing overlaps and the format is a first format that can indicate which part of the data is included in the transmitted subframe, then the predetermined subframe is followed Data transmission method determining means for changing a subframe to be transmitted to the predetermined subframe;
A wireless communication apparatus comprising: The data transmission method determining means, when the timing is duplicated and the format is a second format that cannot indicate which part of the data is included in the transmitted subframe, the data On the condition that there is a vacant channel resource used for transmission, the format used for data transmission is changed to the first format, and the subframe to be transmitted next is changed to the predetermined subframe. The wireless communication device according to claim 1.   When the data transmission method determination means is a second format in which the timing is duplicated and the format is not able to indicate which part of the data is included in a subframe in which the format is transmitted, The radio communication apparatus according to claim 1, wherein the number of allocated resource blocks is increased until systematic bits included in the plurality of subframes exceed a certain ratio.   The wireless communication apparatus according to claim 1, further comprising: a transmission timing determination unit that does not assign a timing at which a multicast communication or broadcast communication subframe is transmitted to a timing overlapping with the predetermined subframe in the data transmission.   2. The radio communication apparatus according to claim 1, wherein among the plurality of subframes, the predetermined subframe is a subframe including more systematic bits than a subframe to be transmitted next to the predetermined subframe. .   6. The radio communication apparatus according to claim 5, wherein the data has a structure in which a parity bit is connected after a systematic bit, and the predetermined subframe is a subframe including an initial portion of the data.   The wireless communication according to claim 6, further comprising: excluding means for excluding the subframe from the decoding target in the wireless communication terminal device when a subframe transmitted first in the initial transmission of the data is not the predetermined subframe. apparatus. Other information to be transmitted in preference to the data is transmitted at a timing at which the initial transmission of the data is performed unless the other information is transmitted,
The wireless communication apparatus according to claim 1, wherein the predetermined subframe is a subframe including a head of the data. A wireless communication device for transmitting data composed of systematic bits and parity bits in a predetermined format using a plurality of subframes,
Whether the timing at which a predetermined subframe including the systematic bit among the plurality of subframes is transmitted overlaps with the timing at which a subframe of other information to be transmitted with priority over the data is transmitted Determining whether or not,
If the timing overlaps and the format is a first format that can indicate which part of the data is included in the transmitted subframe, then the predetermined subframe is followed Changing a subframe to be transmitted to the predetermined subframe;
A wireless communication method comprising:

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