JP2011239282A - Wireless communication base station device, wireless communication terminal unit, and rate matching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication base station device, a wireless communication terminal unit, and a rate matching method which enhance a coding gain and reduce an error rate.SOLUTION: A CQI-M determination section 101 determines Mcorresponding to a downlink CQI as a CQI-M. A PER-M determination section 102 determines Mcorresponding to a downlink PER as a PER-M. A UE-M determination section 103 determines Mcorresponding to the number of UEs accessing a base station device as a UE-M. An Mdetermination section 104 selects the lowest Mout of the CQI-M, PER-M, and UE-M. An Ncalculation section 105 receives a transmission channel and calculates the size of an empty buffer of an unused channel. An Ndetermination section 106 obtains Nby dividing a value obtained through the addition of the soft buffer size and the empty buffer size by Mwhich is multiplied by 1 or 2 according to a communication mode.

Description

  The present invention relates to a radio communication base station apparatus, a radio communication terminal apparatus, and a rate matching method.

  In LTE (Long Term Evolution), which is one of the next generation communication standards, the following communication methods are used for transmission of DLSCH (Down Link Shared Channel), PCH (Paging Channel) and MCH (Multicast Channel) transport channels Has been agreed.

  When a cyclic redundancy check (CRC) bit is added to the transmission data and the data size after the CRC addition exceeds 6144, the data is divided. Data having a size of 6144 or less is called a code block (CB). When the number of code blocks becomes 2 or more, CRC is added to each code block.

  Also, turbo coding is performed with a coding rate R = 1/3 in units of code blocks, and systematic bits and parity bits (two types) are generated. Sub-block interleaving is performed for each of the generated systematic bits and parity bits, and the parity bits subjected to sub-block interleaving are combined after the systematic bits subjected to sub-block interleaving.

  The combined data is stored in a circular buffer and rate matching is performed in units of code blocks.

  Further, the data of each code block stored in the circular buffer is extracted from the position specified by RV (Redundancy Version) for the specified size, and the data of each code block is combined to obtain transmission data.

In LTE, a transmission mode (Transmission Mode) is specified for downlink transmission, and examples include SISO (Single Input Single Output), transmission diversity (Transmission Diversity), and MIMO (Multiple Input Multiple Output). . The soft buffer size (N _soft ) in the downlink physical layer is defined for UE categories 1 to 5 (UE Categories 1 to 5). Here, the UE category is a downlink physical layer parameter set indicating the performance of the terminal that defines the maximum transport block size in the physical layer, the soft buffer size of the terminal, the maximum number of spatial multiplexing layers, and the like. Note that not only downlink but also uplink is defined. The maximum throughput is categorized and the buffer size (because it is a rate match parameter) is defined accordingly. The relationship between the UE category and N _soft is shown in Table 1 below.

When the transmission data size after downlink encoding is larger than the soft buffer size of the UE (User Equipment), the rate match is less than the buffer size of the UE. The sizes of the transport block (N _IR ) and the code block (N _cb ) are obtained by the following equations (1) and (2), respectively.

In the above equation (1), N _IR indicates the soft buffer size for the transport block, and N _soft indicates the soft buffer size. K _MIMO is 2 when the communication mode is MIMO, and 1 otherwise. M _{DL_HARQ} indicates the number of HARQ processes, and is 8 in FDD (Frequency Division Duplex). M _limit is 8.

In the above equation (2), N _cb represents the soft buffer size per code block, C represents the number of code blocks, and K _w represents the circular buffer length.

  When retransmission occurs due to transmission with a data size equal to or less than the buffer size of the UE, HARQ synthesis can be performed without discarding the previously received data, so reception processing is performed without loss of coding gain and retransmission gain. Can do.

Since N _soft is a specified value, K _MIMO is 1 or 2, and min (M _{DL_HARQ} , M _limit ) is 8 in FDD, N _IR can be considered as a fixed value unless the transmission mode is changed.

3GPP TS 36.212 v8.7.0, 3rd Generation Partnership Project, Technical Specification Group Radio Access Network, Evolved Universal Terrestrial Radio Access, Multiplexing

However, since K _MIMO cannot be dynamically changed, _NIR becomes a fixed value, the amount of parity bits that can be transmitted cannot be increased or decreased according to the communication status, and the coding gain decreases, resulting in an error. There is a problem that the rate becomes high.

  An object of the present invention is to provide a radio communication base station apparatus, a radio communication terminal apparatus, and a rate matching method that increase the coding gain and reduce the error rate.

  The radio communication base station apparatus of the present invention includes a variable parameter determination means for determining a variable parameter based on a downlink CQI, a downlink packet error rate, and the number of wireless communication terminal apparatuses being accessed, and a communication mode. Accordingly, a configuration is provided that includes a determination unit that determines the soft buffer size per transport block by dividing the soft buffer size by the variable parameter that is multiplied by 1 or 2 accordingly.

  The wireless communication terminal apparatus according to the present invention includes a variable parameter determining means for determining a variable parameter based on a downlink CQI, a downlink packet error rate, and the number of wireless communication terminal apparatuses being accessed, and a communication mode. And determining means for determining the soft buffer size per transport block by dividing the soft buffer size by the variable parameter multiplied by 1 or 2.

  The rate matching method of the present invention includes a variable parameter determination step for determining a variable parameter based on a downlink CQI, a downlink packet error rate, and the number of wireless communication terminal devices being accessed, and a communication mode. And determining the soft buffer size per transport block by dividing the soft buffer size by the variable parameter multiplied by 1 or 2.

  According to the present invention, the coding gain can be increased and the error rate can be reduced.

The block diagram which shows the structure of the soft buffer size ( _NIR ) determination processing part per transport block which concerns on one embodiment of this invention The figure which shows the relationship between CQI and _MTxEnable The figure which shows the relationship between PER and _MTxEnable The figure which shows the relationship between the number of UEs and _MTxEnable Flow chart showing processing procedure of N _IR determination processing unit Schematic diagram showing how to use the soft buffer size

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(One embodiment)
FIG. 1 is a block diagram showing a configuration of a soft buffer size (N _IR ) determination processing unit 100 per transport block according to an embodiment of the present invention. The N _IR determination processing unit 100 is mounted on the radio communication base station and the UE. Hereinafter, the configuration of the _NIR determination processing unit 100 will be described with reference to FIG.

The CQI-M determination unit 101 stores the relationship between CQI and _MTxEnable as shown in FIG. The CQI-M determination unit 101 receives the downlink CQI, and outputs M _TxEnable corresponding to the received CQI to the M _TxEnable determination unit 104 as CQI-M.

The PER-M determination unit 102 stores the relationship between PER and _MTxEnable as shown in FIG. The PER-M determination unit 102 receives ACK / NACK from the communication partner, measures the downlink PER, and outputs M _TxEnable corresponding to the measured PER to the M _TxEnable determination unit 104 as PER-M.

The UE-M determination unit 103 stores the relationship between the number of transmission UEs and M _TxEnable as illustrated in FIG. The UE-M determination unit 103 receives the number of UEs that are accessing the base station apparatus, and outputs the M _TxEnable corresponding to the received number of UEs to the M _TxEnable determination unit 104 as UE-M.

The M _TxEnable determining unit 104 includes the CQI-M output from the CQI-M determining unit 101, the PER-M output from the PER-M determining unit 102, and the UE-M output from the UE-M determining unit 103. Among them, the lowest _MTxEnable is selected and output to the N _IR determination unit 106. Note that _MTxEnable is the number of subframes that can be transmitted during RTT (Round Trip Time), and is a variable parameter.

The N _Enable calculation unit 105 receives a transmission channel, calculates an empty buffer size (N _Enable ) of an unused channel, and outputs it to the N _IR determination unit 106.

The N _IR determination unit 106 receives the SISO / MIMO information (communication mode), sets K _MIMO = 1 if SISO and K _MIMO = 2 if MIMO, and outputs M _TxEnable , M _TxEnable , output from the M _TxEnable determination unit 104 using _{N Enable} output from N _Enable calculating unit 105 obtains the _{N IR} the following formula (3), and outputs.

Next, the processing procedure of the above-described N _IR determination processing unit 100 will be described with reference to FIG. In FIG. 5, in ST201, the CQI-M determination section 101 determines _MTxEnable corresponding to the downlink CQI as CQI-M. Specifically, when CQI is low (bad communication environment), _MTxEnable is reduced, and when CQI is high (communication environment is good), _MTxEnable is increased. However, the maximum value of _MTxEnable is RTT.

In ST202, the PER-M determining section 102 determines _MTxEnable corresponding to the downlink PER as PER-M. Specifically, when the PER is low (the error rate is high or the number of residual packets is large), M _TxEnable is decreased, and when the PER is high (the error rate is low or the number of residual packets is small), M _{Increase TxEnable} . However, the maximum value of _MTxEnable is RTT.

In ST203, UE-M determining section 103 determines M _TxEnable corresponding to the number of UEs as UE-M. Specifically, M _TxEnable is decreased when the number of UEs is large, and M _TxEnable is increased when the number of UEs is small. However, the maximum value of _MTxEnable is RTT. In addition, you may perform the process of ST201-203 simultaneously.

In ST _{204, M TxEnable} determination unit 104, among the _{M TxEnable} determined in ST201～203, determines the minimum _{M TxEnable.}

In ST205, the N _Enable calculation unit 105 searches for an empty buffer of an unused channel and obtains an empty buffer size N _Enable . The target channels are PDCCH (control channel), MCH (broadcast channel), and BCH (Physical-BCH, Dynamic-BCH). When the channel is not used, the free buffer size of each channel is added to N _Enable . Note that if there is no free buffer, N _Enable = 0.

In ST206, according to the SISO / MIMO information acquired by the N _IR determining unit 106, K _MIMO = 1 for SISO, K _MIMO = 2 for _MIMO , and N _soft , M _TxEnable , and N _Enable are _expressed by the formula (3). ) to by substituting determine the _{N IR.}

As shown in Equation (3), N _IR is a value obtained by adding the _soft buffer size (N _soft ) in the downlink physical layer and the empty buffer size (N _Enable ) of the unused channel, and the number of CQI, PER, and UE _Is divided by a value that is 1 or 2 times the variable parameter (M _TxEnable ) determined based on the above.

FIG. 6 is a schematic diagram showing how to use the soft buffer size. Here, a case where N _IR is composed of 7 code blocks is shown. FIG. _6A shows a conventional method of use, where M _TxEnable is 8 and N _Enable is 0. In the conventional usage method, _NIR becomes a fixed value, and the reception buffer size becomes small. On the other hand, FIG. 6 (b) shows a usage by _{N IR} determination processing according to the present _{embodiment, M TxEnable} indicates the case of _{6, N Enable>} 0.

In the usage method according to the present embodiment, since M _TxEnable is a variable parameter, the transmit buffer size that can be transmitted can be increased. That is, the _NIR can be made variable, thereby enabling rate matching. Compared with FIG. 6 (a), FIG. 6 (b) can increase the transmission amount of parity bits, thereby increasing the coding gain and lowering the error rate, thereby improving the throughput. Can be planned. In addition, the available reception buffer size can be increased by using an unused channel empty buffer.

As described above, according to the present embodiment, a value obtained by adding the _soft buffer size (N _soft ) in the downlink physical layer and the empty buffer size (N _Enable ) of the unused channel is based on the CQI, PER, and the number of UEs. By dividing by a value that is 1 or 2 times the variable parameter (M _TxEnable ) determined in this way to obtain N _IR , it is possible to increase the transmission buffer size that can be transmitted and increase the transmission amount of parity bits. Therefore, the coding gain can be increased, the error rate can be reduced, and the throughput can be improved.

In the present embodiment, the minimum value among CQI-M, PER-M, and UE-M is determined as _MTxEnable , but it may be determined only by CQI-M or PER-M.

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

_{DESCRIPTION OF SYMBOLS} 101 CQI-M determination part 102 PER-M determination part 103 UE-M determination part 104 M _TxEnable determination part 105 N _Enable calculation part 106 N _IR determination part

Claims (9)

Variable parameter determining means for determining a variable parameter based on the downlink CQI, the downlink packet error rate, and the number of wireless communication terminal devices being accessed;
Determining means for determining the soft buffer size per transport block by dividing the soft buffer size by the variable parameter multiplied by 1 or 2 according to the communication mode;
A wireless communication base station apparatus comprising:   First variable parameter determining means for determining the first variable parameter by decreasing the first variable parameter when the downlink CQI is low and increasing the first variable parameter when the downlink CQI is high. The radio communication base station apparatus according to claim 1 provided.   When the downlink packet error rate is low, the second variable parameter is decreased, and when the downlink packet error rate is high, the second variable parameter is increased and the second variable parameter is determined. The radio communication base station apparatus according to claim 1, further comprising parameter determination means.   The third variable parameter is determined by decreasing the third variable parameter when the number of wireless communication terminal devices being accessed is large, and increasing the third variable parameter when the number of wireless communication terminal devices being accessed is small. The wireless communication base station apparatus according to claim 1, further comprising third variable parameter determination means.   The variable parameter determining means includes a first variable parameter obtained based on the downlink CQI, a second variable parameter obtained based on the downlink packet error rate, and the number of wireless communication terminal devices being accessed. The wireless communication base station apparatus according to claim 1, wherein the smallest variable parameter is determined among the third variable parameters obtained based on the base station. An empty buffer size calculating means for calculating the size of an unused channel empty buffer;
The radio communication base station apparatus according to claim 1, wherein the determination unit divides a value obtained by adding the empty buffer size to the soft buffer size.   The radio communication base station apparatus according to claim 1, wherein the variable parameter is the number of subframes that can be transmitted during a round trip time. Variable parameter determining means for determining a variable parameter based on the downlink CQI, the downlink packet error rate, and the number of wireless communication terminal devices being accessed;
Determining means for determining the soft buffer size per transport block by dividing the soft buffer size by the variable parameter multiplied by 1 or 2 according to the communication mode;
A wireless communication terminal apparatus comprising: A variable parameter determining step for determining a variable parameter based on the downlink CQI, the downlink packet error rate, and the number of wireless communication terminal devices being accessed;
A decision step of determining the soft buffer size per transport block by dividing the soft buffer size by the variable parameter multiplied by 1 or 2 according to the communication mode;
A rate matching method comprising:

Images