The present invention relates to a wireless communication system, and more particularly to an apparatus and method for transmitting control information.
Wireless communication systems are widely used to provide various kinds of communication services such as voice or data services. Generally, a wireless communication system is a multiple access system that can communicate with multiple users by sharing available system resources (bandwidth, transmission (Tx) power, and the like). A variety of multiple access systems can be used, for example, a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, a Multi-Carrier Frequency Division Multiple Access (MC-FDMA) system, and the like.
Accordingly, the present invention is directed to a method and apparatus for transmitting an uplink signal that substantially obviate one or more problems due to limitations and disadvantages of the related art.
An object of the present invention devised to solve the problem lies on a method and apparatus for effectively transmitting an uplink signal in a wireless communication system. Another object of the present invention devised to solve the problem lies on a method and apparatus for effectively transmitting control information. A further object of the present invention devised to solve the problem lies on a method and apparatus for effectively multiplexing control information and data.
It is to be understood that objects to be achieved by the present invention are not limited to the aforementioned objects and other objects which are not mentioned will be apparent to those of ordinary skill in the art to which the present invention pertains from the following description.
The object of the present invention can be achieved by providing a method for transmitting an uplink signal by a communication apparatus in a wireless communication system, the method including channel encoding control information; and multiplexing the channel encoded control information with a plurality of data blocks by performing channel interleaving, wherein the number of channel encoded symbols for the control information is determined using an inverse number of the sum of a plurality of spectral efficiencies (SEs) for initial transmission of the plurality of data blocks.
In another aspect of the present invention, provided herein is a communication apparatus for transmitting an uplink signal in a wireless communication system including a radio frequency (RF) unit, and a processor, wherein the processor channel-encodes control information, and performs channel interleaving, such that the channel encoded control information is multiplexed with a plurality of data blocks, and the number of channel encoded symbols for the control information is determined using an inverse number of the sum of a plurality of spectral efficiencies (SEs) for initial transmission of the plurality of data blocks.
The spectral efficiency (SE) for initial transmission of each data block is given as the following equation:
where, PayloadData is a size of a data block, NRE
The number of channel encoded symbols for the control information is determined by the following equation:
where, PayloadUCI is a size of the control information, SEData(i) is a spectral efficiency for initial transmission of an i-th data block, βoffsetPUSCH is an offset value, α is an integer of 1 or higher, λ′i is a constant, N is a total number of data blocks, and ┌ ┐ is a ceiling function.
The number of channel encoded symbols for the control information is determined by the following equation:
where, PayloadUCI is a size of the control information, PayloadData(1) is a size of a first data block, NRE
NRE
where, MscPUSCH(i)-initial is the number of scheduled subcarriers for initial PUSCH transmission of the i-th data block, NsymbPUSCH(i)-initial is the number of SC-FDMA symbols for initial PUSCH transmission of the i-th data block, C(i) is the number of code blocks of the i-th data block, Kr(i) is a size of r-th code block of the i-th data block, and r is an integer of 0 or higher.
N is set to 2 (N=2), α is set to 1 (α=1), λ1 is set to 1 (λ1=1), and λ2 is set to 1 (λ2=1).
The control information is acknowledgement/negative acknowledgement (ACK/NACK) or Rank Indicator (RI).
In another aspect of the present invention, provided herein is a method for transmitting an uplink signal by a communication apparatus in a wireless communication system, the method including: channel encoding control information; and multiplexing the channel encoded control information with one of a plurality of data blocks by performing channel interleaving, wherein the number of channel encoded symbols for the control information is determined by the following equation:
where, α is an integer of 1 or higher, PayloadUCI is a size of the control information, NRE
In another aspect of the present invention, provided herein is a communication apparatus for transmitting an uplink signal including a radio frequency (RF) unit; and a processor, wherein the processor channel-encodes control information, and performs channel interleaving, such that the channel encoded control information is multiplexed with a plurality of data blocks, and the number of channel encoded symbols for the control information is determined by the following equation:
where, α is an integer of 1 or higher, PayloadUCI is a size of the control information, NRE
NRE
where MscPUSCH(x)-initial is the number of scheduled subcarriers for initial PUSCH transmission of the data block x, NsymbPUSCH(x)-initial is the number of SC-FDMA symbols for initial PUSCH transmission of the data block x, C(x) is the number of code blocks of the data block x, Kr(x) is a size of r-th code block of the data block x, and r is an integer of 0 or higher.
α is set to 1 (α=1).
The control information may include information related to channel quality.
The control information may include at least one of a Channel Quality Indicator (CQI) and a Precoding Matrix Indicator (PMI).
Exemplary embodiments of the present invention have the following effects. The method and apparatus for transmitting an uplink signal according to the present invention can effectively transmit an uplink signal in a wireless communication system. In addition, control information and data can be effectively multiplexed.
It is to be understood that the advantages that can be obtained by the present invention are not limited to the aforementioned advantages and other advantages which are not mentioned will be apparent from the following description to the person with an ordinary skill in the art to which the present invention pertains.
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the invention. The following embodiments of the present invention can be applied to a variety of wireless access technologies, for example, CDMA, FDMA, TDMA, OFDMA, SC-FDMA, MC-FDMA, and the like. CDMA can be implemented by wireless communication technologies, such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented by wireless communication technologies, for example, a Global System for Mobile communications (GSM), a General Packet Radio Service (GPRS), an Enhanced Data rates for GSM Evolution (EDGE), etc. OFDMA can be implemented by wireless communication technologies, for example, IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, E-UTRA (Evolved UTRA), and the like. UTRA is a part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of an Evolved UMTS (E-UMTS) that uses an E-UTRA. The LTE-Advanced (LTE-A) is an evolved version of 3GPP LTE.
Although the following embodiments of the present invention will hereinafter describe inventive technical characteristics on the basis of the 3GPP LTE/LTE-A system, it should be noted that the following embodiments will be disclosed only for illustrative purposes and the scope and spirit of the present invention are not limited thereto. Specific terms used for the exemplary embodiments of the present invention are provided to aid in understanding of the present invention. These specific terms may be replaced with other terms within the scope and spirit of the present invention.
Referring to
Referring to
Referring to
Referring to
Control information transmitted over a PDCCH is referred to as Downlink Control Information (DCI). DCI includes resource allocation information for either a UE or a UE group and other control information. For example, DCI includes uplink/downlink (UL/DL) scheduling information, an uplink transmission (UL Tx) power control command, etc.
PDCCH carries a variety of information, for example, transmission format and resource allocation information of a downlink shared channel (DL-SCH), transmission format and resource allocation information of an uplink shared channel (UL-SCH), paging information transmitted over a paging channel (PCH), system information transmitted over the DL-SCH, resource allocation information of an upper-layer control message such as a random access response being transmitted over PDSCH, a set of Tx power control commands of each UE contained in a UE group, a Tx power control command, activation indication information of Voice over IP (VoIP), and the like. A plurality of PDCCHs may be transmitted within a control region. A user equipment (UE) can monitor a plurality of PDCCHs. PDCCH is transmitted as an aggregation of one or more contiguous control channel elements (CCEs). CCE is a logical allocation unit that is used to provide a coding rate based on a radio channel state to a PDCCH. CCE may correspond to a plurality of resource element groups (REGs). The format of PDCCH and the number of PDCCH bits may be determined according to the number of CCEs. A base station (BS) decides a PDCCH format according to DCI to be sent to the UE, and adds a Cyclic Redundancy Check (CRC) to control information. The CRC is masked with an identifier (e.g., Radio Network Temporary Identifier (RNTI)) according to a PDCCH owner or a purpose of the PDCCH. For example, provided that the PDCCH is provided for a specific UE, an identifier of the corresponding UE (e.g., cell-RNTI (C-RNTI)) may be masked with the CRC. If PDCCH is provided for a paging message, a paging identifier (e.g., paging-RNTI (P-RNTI)) may be masked with a CRC. If. PDCCH is provided for system information (e.g., system information block (SIC)), system information RNTI (SI-RNTI) may be masked with CRC. If PDCCH is provided for a random access response, random access-RNTI (RA-RNTI) may be masked with CRC. Control information transmitted over PDCCH is referred to as downlink control information (DCI). DCI includes resource allocation information for a UE or a UE group and other control information. For example, DCI includes UL/DL scheduling information, an uplink Tx power control command, etc.
Table 1 shows a DCI format 0 for uplink scheduling. In Table 1, although the size of the RB allocation field is denoted by 7 bits, the scope or spirit of the present invention is not limited thereto, the actual size of the RB allocation field can be changed according to system bandwidth.
Table 2 shows information of an MCS index for enabling the LTE to transmit uplink (UL) data. 5 bits are used for MCS. Three states (IMCS=29˜31) from among several states, each of which is capable of being denoted by 5 bits, are used for uplink (UL) retransmission.
Referring to
PUCCH may be used to transmit the following control information, i.e., Scheduling Request (SR), HARQ ACK/NACK, and a Channel Quality Indicator (CQI), and a detailed description thereof will hereinafter be described.
Table 3 shows the mapping relationship between PUCCH format and UCI for use in LTE.
In LTE-A, two methods may be used to simultaneously transmit UCI and UL-SCH data. A first method simultaneously transmits PUCCH and PUSCH. A second method multiplexes UCI to a PUSCH in the same manner as in the legacy LTE.
Since the legacy LTE UE is unable to simultaneously transmit PUCCH and PUSCH, it multiplexes UCI to a PUSCH region when UCI (e.g., CQI/PMI, HARQ-ACK, RI, etc.) transmission is needed for a subframe via which PUSCH is transmitted. For example, provided that CQI and/or PMI (CQI/PMI) transmission is needed for a subframe to which PUSCH transmission is allocated, the UE multiplexes UL-SCH data and CQI/PMI prior to DFT spreading, and then simultaneously transmits control information and data over PUSCH.
Referring to
All the transport blocks (TBs) are used to calculate CRC parity bits. Transport Block (TB) bits are denoted by α0, α1, α2, α3 . . . αA-1. Parity bits are denoted by p0, p1, p2, p3, . . . pL-1. The size of TBs is denoted by A, and the number of parity bits is denoted by L.
After performing transport block (TB) CRC attachment, code block segmentation and code block CRC attachment are performed at step S110. Input bits for code block segmentation are denoted by b0, b1, b2, b3, . . . , bB-1, where B denotes the number of bits of a TB (including CRC). Bits provided after code block segmentation are denoted by cr0, cr1, cr2, cr3, . . . , cr(K
The channel coding is performed after performing the code block segmentation and code block CRC attachment at step S120. Bits after channel coding are denoted by dr0(i), dr1(i), dr2(i), dr3(i), . . . dr(D
Rate matching may be performed after the channel coding at step S130. Bits provided after rate matching are denoted by er0, er1, er2, er3, . . . , er(E
Code block concatenation is performed after the rate matching at step S140. Bits provided after the code block concatenation are denoted by f0, f1, f2, f3, . . . fG-1 denotes a total number of bits coded for data transmission. If control information is multiplexed with UL-SCH transmission, bits used for control information transmission are not included in ‘G’. f0, f1, f2, f3, . . . fG-1 may correspond to UL-SCH codewords.
In the case of UL control information, channel quality information (CQI and/or PMI), RI and HARQ-ACK are independently channel-coded. UCI channel coding is performed on the basis of the number of coded symbols for each piece of control information. For example, the number of coded symbols may be used for rate matching of the coded control information. In a subsequent process, the number of coded symbols may correspond to the number of modulation symbols or the number of REs.
Channel coding of channel quality information is performed using an input bit sequence o0, o1, o2, o3, . . . oO-1 at step S150. The output bit sequence of the channel coding for channel quality information is denoted by q0, q1, q2, q3, . . . , qQ
Channel coding of RI is performed using an input bit sequence [o0RI] or [o0RI o1RI] at step S160. [o0RI] and [o0RI o1RI] denote 1-bit RI and 2-bit RI, respectively.
In the case of the 1-bit RI, repetition coding is used. In the case of the 2-bit RI, the (3,2) simplex code is used, and the encoded data may be cyclically repeated.
Table 4 exemplarily shows channel coding of the 1-bit RI, and Table 5 exemplarily shows channel coding.
In Tables 4 and 5, Qm is a modulation order. o2RI is denoted by o2RI=(o0RI+o1RI)mod 2, and ‘mod’ is a modulo operation. ‘x’ or ‘y’ is a place holder for maximizing a Euclidean distance of a modulation symbol carrying RI information when the RI bit is scrambled. Each of ‘x’ and ‘y’ has the value of 0 or 1. The output bit sequence q0RI, q1RI, q2RI, . . . , qQ
The channel coding of HARQ-ACK is performed using the input bit sequence [o0ACK], [o0ACK o1ACK], or [o0ACK o1ACK . . . oO
Table 6 exemplarily shows channel coding of HARQ-ACK. Table 7 exemplarily shows channel coding of 2-bit HARQ-ACK.
In Tables 6 and 7, Qm is a modulation order. For example, Qm=2 may correspond to QPSK, Qm=4 may correspond to 16QAM, and Qm=6 may correspond to 64QAM. o0ACK may correspond to an ACK/NACK bit for a codeword 0, and o1ACK may correspond to an ACK/NACK bit for a codeword 1. o2ACK is denoted by o2ACK=(o0ACK+o1ACK)mod 2, and ‘mod’ is a modulo operation. ‘x’ or ‘y’ is a place holder for maximizing a Euclidean distance of a modulation symbol carrying HARQ-ACK information when the HARQ-ACK bit is scrambled. Each of ‘x’ and ‘y’ has the value of 0 or 1. QACK is a total number of coded bits, the bit sequence q0ACK, q1ACK, q2ACK, . . . , qQ
The inputs of a data and control multiplexing block (also called ‘data/control multiplexing block’) are coded UL-SCH bits denoted by f0, f1, f2, f3, . . . , fG-1 and coded CQI/PMI bits denoted by q0, q1, q2, q3, . . . , qQ
The channel interleaver multiplexes control information and UL-SCH data for PUSCH transmission. In more detail, the channel interleaver includes a process of mapping control information and UL-SCH data to a channel interleaver matrix corresponding to PUSCH resources.
After execution of channel interleaving, the bit sequence h0, h1, h2, . . . , hH+Q
Referring to
In LTE, control information (e.g., QPSK modulated) may be scheduled in a manner that the control information can be transmitted over PUSCH without UL-SCH data. Control information (CQI/PMI, RI and/or ACK/NACK) is multiplexed before DFT spreading so as to retain low CM (Cubic Metric) single-carrier characteristics. Multiplexing of ACK/NACK, RI and CQI/PMI is similar to that of
If UCI is transmitted over PUSCH, the UE must determine the number Q′UCI of encoded symbols for UCI so as to perform channel coding (See S150, S160 and S170 of
A method for deciding the number (Q′) of encoded symbols for UCI in legacy LTE will hereinafter be described using CQI/PMI as an example. Equation 1 indicates an equation defined in LTE.
In Equation 1, ‘0’ denotes the number of CQI/PMI bits, and ‘L’ denotes the number of CRC bits. If ‘O’ is equal to or less than 11, L is set to 0. If ‘O’ is higher than 12, L is set to 8. QCQI is denoted by QCQI=Qm·Q′, and Qm is a modulation order. QRI denotes the number of encoded RI bits. If RI is not transmitted, Q, is set to 0 (QRI=0). βoffsetPUSCH denotes an offset value, and may be adapted to adjust the coding rate of CQI/PMI. βoffsetPUSCH may also be denoted by βoffsetPUSCH=βoffsetCQI. MscPUSCH-initial is a band that is scheduled for initial PUSCH transmission of a transport block (TB). NsymbPUSCH-initial is the number of SC-FDMA symbols for each subframe for initial PUSCH transmission of the same transport block (TB), and may also be denoted by NsymbPUSCH-initial=(2·(NsymbUL−1)−NSRS). NsymbUL denotes the number of SC-FDMA symbols for each slot, NSRS is 0 or 1. In the case where the UE is configured to transmit PUSCH and SRS in a subframe for initial transmission or in the case where PUSCH resource allocation for initial transmission partially or entirely overlaps with a cell-specific SRS subframe or band, NSRS is set to 1. Otherwise, NSRS is set to 0.
denotes the number of bits of data payload (including CRC) for initial PUSCH transmission of the same transport block (TB). C is a total number of code blocks, r is a code block number, and Kr is the number of bits of a code block (r). MscPUSCH-initial, C, and Kr are obtained from initial PDCCH for the same transport block (TB). ┌n┘ is a ceiling function, and returns the smallest integer from among at least n values. ‘min(a,b)’ returns the smallest one of ‘a’ and ‘b’
The part (2) for an upper limit is removed from Equation 1, but only the part (1) can be represented by the following equation 2.
In Equation 2, PayloadUCI is the sum of the number (O) of UCI bits and the number (L) of CRC bits (i.e., PayloadUCI=O+L). In legacy LTE, if UCI is ACK/NACK or RI, the number (L) of CRC bits is set to 0. If UCI is CQI/PMI and the CQI/PMI is composed of 11 bits or less, L is set to 0 (i.e., L=0). Otherwise, if UCI is CQI/PMI and the CQI/OMI is composed of 12 bits or higher, L is set to 8 (i.e., L=8). Payload)Data is the number of bits of data payload (including CRC) for initial PUSCH transmission recognized through either initial PDCCH or a random access response grant for the same transport block (TB). NRE
In Equation 2, PayloadData/NRE
In Equation 3, PayloadData/Qm·NRE
In the present invention, SE is a spectral efficiency SEData) for UL-SCH data (i.e., a transport block (TB)) in so far as the SE is not mentioned specially in a different manner. SE may also denote PayloadData/NRE
In the case of HARQ-ACK, L is set to 0 (i.e., L=0), βoffsetPUSCH is set to βoffsetPUSCH-ACK (i.e., βoffsetPUSCH=βoffsetHARQ-ACK), and the number of coded symbols is determined in the same manner as in Equation 1 other than the part (2) indicating the upper limit. Similarly, in the case of RI, L is set to 0 (i.e., L=0), is set to βoffsetRI (i.e., βoffsetPUSCH=βoffsetRI), and the number of coded symbols is determined in the same manner as in Equation 1 other than the part (2) indicating the upper limit.
The above-mentioned description may be applied only when one codeword (corresponding to a TB) is transmitted over a PUSCH, because the legacy LTE does not support a single user (SU)-MIMO. However, LTE-A supports SU-MIMO, so that several codewords can be transmitted over a PUSCH. Therefore, a method for multiplexing a plurality of codewords and UCI is needed.
A method for effectively multiplexing several pieces of data and UCI in a PUSCH will hereinafter be described with reference to the annexed drawing. For convenience of description, although UL-SCH transmission will be described on the basis of a codeword, a transport block (TB) and a codeword are equivalent data blocks. Therefore, the equivalent data blocks may be commonly known as ‘UL-SCH data block’. In addition, the codeword may be replaced with a corresponding transport block (TB), or vice versa. The relationship between the codeword and the transport block (TB) may be changed by codeword swapping. For example, a first TB and a second TB may correspond to a first codeword and a second codeword, respectively. On the other hand, if codeword swapping is applied, the first TB may correspond to the second codeword, and the second TB may correspond to the first codeword. The HARQ operation is performed on the basis of a transport block (TB). The following embodiments may be implemented independently or collectively.
In accordance with the present invention, when two or more codewords are transmitted, UCI is multiplexed to a layer via which a specific codeword is transmitted so that the multiplexed result is transmitted. Preferably, a specific codeword may be selected according to information of a new data indicator (NDI) capable of discriminating between new transmission (or initial transmission) and retransmission. UCI is multiplexed to all or some of a layer via which the corresponding codeword is transmitted.
For example, in the case where two codewords are all in new transmission (or initial transmission), UCI may be multiplexed to a layer via which a first codeword (or a transport block TB) is transmitted. In another example, in the case where one of two codewords corresponds to new transmission and the other one corresponds to retransmission (i.e., a codeword of new transmission and a codeword of retransmission are mixed), UCI may be multiplexed to a layer via which a codeword of new transmission is transmitted. Preferably, the size of resources (e.g., the number of REs) (corresponding to the number of modulation symbols or the number of coded symbols) where the UCI is multiplexed may be decided according to the number of REs via which the corresponding codeword is transmitted, the modulation scheme/order, the number of bits of data payload, and an offset value. Preferably, in order for UCI resources to be determined to be an MCS (Modulation and Coding Scheme) function of the corresponding codeword, UCI can be multiplexed to all layers for transmitting the corresponding codeword.
In the case where the new transmission and the retransmission are present, the reason why the UCI is multiplexed to the codeword corresponding to the new transmission is as follows. In HARQ initial transmission, a data transport block size (TBS) of a PUSCH is established to satisfy a target Frame Error Rate (FER) (e.g., 10%). Therefore, when data and UCI are multiplexed and transmitted, the number of REs for the UCI is defined as a function of the number of REs allocated for transmission of both a data TBS and a PUSCH, as shown in Equation 2. On the other hand, when UCI is multiplexed to a PUSCH retransmitted by HARQ, the UCI can be multiplexed using a parameter having been used for initial PUSCH transmission. In order to reduce resource consumption during transport block (TB) retransmission, the BS may allocate a smaller amount of PUSCH resources as compared to the initial transmission, such that there may arise an unexpected problem when the size of UCI resources is decided by a parameter corresponding to retransmission. Accordingly, in the case where HARQ retransmission occurs, the size of UCI resources may be determined using a parameter used for initial PUSCH transmission. However, assuming that there is a high difference in channel environment between initial transmission and retransmission in association with the same codeword, transmission quality of UCI may be deteriorated when the size of UCI resources is decided using the parameter used for initial PUSCH transmission. Therefore, the retransmission codeword and the initial transmission codeword are simultaneously transmitted, UCI is multiplexed to an initial transmission codeword, so that the amount of UCI resources can be adaptively changed even when the channel environment is changed.
In another example, if all codewords correspond to retransmission, two methods can be used. A first method can be implemented by multiplexing a UCI to a first codeword (or TB). A second method can be implemented by multiplexing a UCI to a codeword to which the latest UCI was multiplexed. In this case, the amount of UCI resources can be calculated using either information of a codeword related to the latest initial transmission or information of a codeword that has been retransmitted the smallest number of times, such that UCI resources can be most appropriately adapted to channel variation.
In accordance with embodiment 1B, in the case where one of two codewords corresponds to new transmission, and the other one corresponds to retransmission (i.e., a new transmission codeword and a retransmission codeword are mixed), UCI may be multiplexed to a layer via which the retransmission codeword is transmitted. In the case of using a successive interface cancellation (SIC) receiver, a retransmission codeword having a high possibility of causing rapid termination is first decoded and at the same time that UCI is decoded, and interference affecting the new transmission codeword can be removed using the decoded retransmission codeword. Provided that the base station (BS) uses the SIC receiver, if UCI is multiplexed to a layer via which the new transmission codeword is transmitted (See Embodiment 1A), latency for enabling the BS to read UCI may be unavoidably increased. The method shown in the embodiment 1B can be implemented by multiplexing UCI to a firstly decoded codeword on the condition that the SIC receiver can recognize the firstly decoded codeword. On the other hand, provided that UCI is transmitted to a layer via which a new transmission codeword is transmitted under the condition that new transmission and retransmission are mixed, information corresponding to retransmission is first decoded, and interference is removed from the layer via which the new transmission codeword is transmitted, thereby improving UCI detection performance.
If the UCI is multiplexed to a specific codeword, the corresponding codeword can be transmitted to a plurality of layers, so that UCI can also be multiplexed to a plurality of layers.
Equation 4 exemplarily shows a method for calculating the number (Q′) of coded symbols for UCI under the condition that the UCI is multiplexed to one specific codeword.
In Equation 4, SE)Data is a spectral efficiency (SE), and is given as PayloadData/NRe
Equation 4 is characterized in that a payload size of a codeword via which UCI is multiplexed, the number of REs via which the corresponding codeword is transmitted, and the number (LData) of layers via which the corresponding codeword is transmitted are used to decide the number of encoded symbols for UCI. In more detail, the number of layers for UCI multiplexing is multiplied by the number of time-frequency resource elements (REs), such that a total number of time-frequency-space REs can be applied to the process of calculating UCI resources.
Equation 5 exemplarily shows another method for calculating the number (Q′) of encoded symbols for UCI when the UCI is multiplexed to one specific codeword.
In Equation 5, SEData denotes a spectral efficiency (SE), and is given as PayloadData/NRe
In the same manner as in Equation 4, Equation 5 is also characterized in that a payload size of a codeword via which UCI is multiplexed, and the number of REs via which the corresponding codeword is transmitted are used to decide the number of encoded symbols for the UCI. Differently from Equation 4, Equation 5 is used to calculate the number of resources where UCI is multiplexed (i.e., the number of encoded symbols), and the number of layers where UCI is multiplexed is multiplied by the calculated number of resources. Therefore, the number of UCI resources in all layers where UCI is multiplexed is given as the same number.
In accordance with the embodiment 1C), if several codewords (e.g., two codewords) (or transport blocks TBs) are transmitted, UCI can be multiplexed to a codeword (or a transport block TB) selected according to the following rules. Preferably, UCI includes channel state information (or channel quality control information). For example, UCI includes CQI and/or CQI/PMI.
Rule 1.1) CQI is multiplexed to a codeword (or a TB) having the highest IMCS. Referring to Table 2, the higher the IMCS value, the better the channel state for the corresponding codeword (or TB). Accordingly, CQI is multiplexed to a codeword (or a TB) having the highest IMCS value, such that reliability of transmitting channel state information can be increased.
Rule 1.2) If two codewords (or two TBs) have the same IMCS value, CQI is multiplexed to Codeword 0 (i.e., a first codeword).
a) exemplarily shows some parts of a DCI format to be newly added for LTE-A uplink MIMO. Referring to
b) exemplarily shows that two transport blocks (or two codewords) are transmitted and UCI (e.g., channel quality control information) is multiplexed to one (or one codeword) of two transport blocks. Since each of CW0 and CW1 has an MCS of 28 or less and an NDI field is toggled, this means that all of two transport blocks correspond to initial transmission. Since a CQI request field is set to 1 (CQI request=1), aperiodic CQI is multiplexed along with data. Although the CQI request field is set to 0 (CQI request=0), if periodic CQI transmission having PUSCH transmission is planned, the periodic CQI is multiplexed along with data. CQI may include a CQI-only format or a (CQI+PMI) format. In this case, according to the above-mentioned rules, channel state information is multiplexed to a codeword (CW0) (or a transport block) having the highest IMCS value.
c) exemplarily shows that two transport blocks (or two codewords) are transmitted and UCI (e.g., channel quality control information) is multiplexed to one transport block (or one codeword). Since each of CW0 and CW1 has an MCS/RV of 28 or less and an NDI field is toggled, this means that all of two codewords (CW0 and CW1) correspond to initial transmission. Since a CQI request field is set to 1 (CQI request=1), aperiodic CQI is multiplexed along with data. Although the CQI request field is set to 0 (CQI request=0), if periodic CQI transmission having PUSCH transmission is planned, the periodic CQI is multiplexed along with data. CQI may include a CQI-only format or a (CQI+PMI) format. In this case, according to the above-mentioned rules, since two transport blocks have the same IMCS value, channel state information is multiplexed to a codeword CW1 acting as a first transport block.
Equations 6 and 7 exemplarily show methods for calculating the number (Q′) of encoded symbols for UCI when UCI is multiplexed to one specific codeword according to the above-mentioned rules. Except for the above-mentioned rules, Equations 6 and 7 are identical to Equations 4′ and 5.
In Equations 6 and 7, SEData(x) is a spectral efficiency (SE), and is given as PayloadData(x)/NRe
If the number of encoded symbols for UCI is the number of encoded symbols for each layer or the rank is set to 1, LUCI=LData(x)=1 is established. Equation 1 of the legacy LTE can be modified into the following Equation 8 according to the above-mentioned rules.
In Equation 8, 0 is the number of CQI/PMI bits, and L is the number of CRC bits. If O is 11 or less, L is set to 0. If O is 12 or higher, L is set to 8. QCQI is denoted by QCQI=Qm·Q′, where Qm is a modulation order. QRI is the number of encoded RI bits. If there is no RI transmission, QRI is set to 0 (QRI=0). βoffsetPUSCH is an offset value, and may be used to adjust the coding rate of CQI/PMI. βoffsetPUSCH is given as βoffsetCQI (i.e., βoffsetPUSCH=βoffsetCQI). MscPUSCH(x)-initial is a band scheduled for initial PUSCH transmission of the transport block x, and is represented by the number of subcarriers. NsymbPUSCH(x)-initial is the number of SC-FDMA symbols for each subframe for initial PUSCH transmission of the same transport block (i.e., transport block x), and may also be denoted by NsymbPUSCH(x)-initial=(2·(NsymbUL−1)−NSRS). NsymbUL is the number of SC-FDMA symbols for each slot, and NSRS is 0 or 1. In the case where the UE is configured to transmit PUSCH and SRS in a subframe for initial transmission of the transport block x or in the case where PUSCH resource allocation for initial transmission of the transport block x partially or entirely overlaps with a cell-specific SRS subframe or band, NSRS is set to 1. Otherwise, NSRS is set to 0.
is the number of bits of data payload (including CRC) for initial PUSCH transmission of the same transport block (i.e., a transport block x). C(x) is a total number of code blocks for the transport block x, r is a code block number. Kr is the number of bits of the code block (r) for use in the transport block x. MscPUSCH-initial, C, and Kr are obtained from initial PDCCH for the same transport block (i.e., a transport block x). The transport block x is determined according to the above-mentioned rules 1.1) and 1.2). ┌n┐ is a ceiling function, and returns the smallest integer from among at least n values. ‘min(a,b)’ returns the smallest one of ‘a’ and ‘b’
In accordance with the embodiment 1D), UCI can be multiplexed to a predetermined codeword irrespective of new transmission (initial transmission) or retransmission. In this case, parameters used for calculating UCI resources can be partially or entirely updated even in the case of retransmission through a UL grant or the like. In the legacy LTE, when UCI is multiplexed to retransmission PUSCH, the calculation of UCI resources can be performed using information of the initial PUSCH transmission. In contrast, if the UCI is multiplexed to a retransmission PUSCH, UCI resources can be calculated using information of retransmission PUCSH. If parameters used for the UCI resource calculation are changed due to a channel variation or the like during the retransmission, the embodiment 1D) of the present invention includes the context indicating that the changed parameters are partially or entirely updated and used during the UCI resource calculation. In addition, if the number of layers via which the corresponding codeword is transmitted is changed during the retransmission, the embodiment 1D) of the present invention may also reflect the changed result to UCI multiplexing.
In accordance with the embodiment 1D), in Equation 4, NRe
The embodiment 2A provides a method for calculating the amount of UCI resources when UCI is multiplexed to all layers irrespective of the number of codewords. In more detail, the embodiment 2A) provides a method for calculating the spectral efficiency (SE) of each codeword within a subframe via which UCI is transmitted, and calculating the number of encoded symbols for UCI using the sum of calculated SEs (or an inverse number of the sum of calculated SEs). SE of each codeword may be calculated using parameters for initial PUSCH transmission of the same codeword.
Equation 9 exemplarily shows a method for calculating the number (Q′) of encoded symbols for UCI when UCI is multiplexed to all layers.
In Equation 9, PayloadUCI and βoffsetPUSCH are identical to those of Equation 2. UCI includes CQI/PMI, ACK/NACK or RI. QmUCI is a modulation order for the UCI. Qm(1) is a modulation order of the first transport block, and Qm(2) is a modulation order of the second transport block. PayloadData(1) and PayloadData(2) are associated with a first transport block and a second transport block, respectively, and denote the number of bits of data payload (including CRC) for either initial PDCCH transmission for the corresponding transport block or initial PUSCH transmission recognized through a random access response grant for the corresponding transport block. NRe
Although Equation 9 assumes that QmUCI, Qm(1) and Qm(2) are given independently of each other, QmUCI=Qm(1)=Qm(2) may also be given in the same manner as in LTE. In this case, Equation 9 can be simplified as shown in the following equation 10.
In addition, if the number (Q′) of encoded symbols for UCI may be the number of encoded symbols per layer, or if the rank is 2, LData1=LData2=1 is given so that Equation 10 can be simplified as shown in the following equation 10.
Meanwhile, Equation 9 can be generalized as shown in the following equation 12.
In Equations 12 and 13, α or λi (i=1, . . . , N) is an integer of 1 or higher. λi is a constant, and is given as 1/λi. SEData(i) (where i=1, . . . , N) denotes a spectral efficiency (SE) for initial PUSCH transmission of the i-th transport block, and is given as PayloadData(i)/NRe
Equation 14 shows another method for calculating the number (Q′) of encoded symbols for UCI when the UCI is multiplexed to all codewords. The method shown in Equation 14 calculates an average amount of multiplexed UCI resources on the basis of a layer, and multiplies the calculated average amount by a total number of layers where UCI is multiplexed. The following Equation 14 can also be modified in the same manner as in Equations 10 to 13.
In Equation 14, PayloadUCI, PayloadData(1), PayloadData(2), NRe
Equations 15 and 16 exemplarily show another method for calculating the number (Q′) of encoded symbols for UCI when the UCI is multiplexed to all codewords. The following Equation 14 may also be modified in the same manner as in Equations 10 to 13.
In Equations 15 and 16, PayloadUCI, PayloadData(1), PayloadData(2), NRe
The embodiment 2B provides another method for calculating the amount of UCI resources when UCI is multiplexed to all layers irrespective of the number of codewords. The embodiment 2B calculates the overall spectral efficiency (SE) of all codewords using parameters of initial transmission of all the codewords in a subframe in which UCI is transmitted, and calculating the number of encoded symbols for UCI using the calculated overall SE.
Equations 17 and 18 illustrate values corresponding to NRe
The following Equations 17 and 18 can be modified in the same manner as in Equations 10 to 13.
In Equations 16 and 17, PayloadUCI, PayloadData(1), PayloadData(2), NRe
The embodiment 2C provides another method for calculating the amount of UCI resources when UCI is multiplexed to all layers irrespective of the number of codewords. The embodiment 2C provides a method for calculating the number of encoded symbols for UCI for each transport block. If different codewords have different modulation orders, the embodiment 2C has an advantage in that a modulation order for each codeword can be used as a modulation order of UCI.
Equations 19 and 20 exemplarily illustrate a method (Q′) for calculating the number of encoded symbols for UCI. The method shown in Equations 19 and 20 can calculate the number (Q′1, Q′2, . . . , Q′N) of encoded modulation symbols for UCI for each transport block, as represented by Q′=Q′1+Q′2+ . . . +Q′N. If modulation orders for use in individual transport blocks are different from one another, UCI uses a modulation order (QPSK, 16QAM, or 64QAM) of the multiplexed transport block. The following Equations 19 and 20 can be modified in the same manner as in Equations 10 to 13.
In Equations 19 and 20, PayloadUCI, PayloadData(1), PayloadData(2), NRe
Equations 21 and 22 exemplarily illustrate a method for calculating the number (Q′) of encoded symbols for UCI. The method shown in Equations 21 and 22 can calculate the number (Q′1, Q′2, . . . , Q′n) of encoded modulation symbols for UCI for each transport block, as represented by Q′=Q′1+Q′2+ . . . +QN. If modulation orders for use in individual transport blocks are different from one another, UCI uses a modulation order (QPSK, 16QAM, or 64QAM) of the multiplexed transport block. The following Equations 21 and 22 can be modified in the same manner as in Equations 10 to 13.
In accordance with the method shown in Equations 21 and 22, Q′1 UCI modulation symbols are multiplexed to a first transport block, and Q′2 UCI modulation symbols are multiplexed to a second transport block. In Equation 21, Q′1 or Q′2 denotes a total number of UCI modulation symbols multiplexed to each codeword, and numbers of UCI modulation symbols multiplexed to individual layers within one codeword may be different from one another. On the other hand, as shown in Equation 22, Q′1 or Q′2 denotes an average number of UCI modulation symbols multiplexed to individual layers, so that the same number of UCI modulation symbols is multiplexed to each layer within one codeword.
The embodiment 2D provides a method for calculating the amount of UCI resources when UCI is multiplexed to all layers irrespective of the number of codewords. The embodiment 2D provides a method for calculating the number of encoded symbols for UCI for each transport block.
Differently from the embodiment 2C, the embodiment 2D can calculate the ratio of UCI resources multiplexed to each codeword using the number of layers and modulation order of the corresponding codeword in a current transmission subframe. Equations 23 and 24 exemplarily illustrate a method for calculating the number of encoded symbols for UCI according to the embodiment 2D. The embodiment 2D shown in Equations 23 and 24 can calculate the number (Q′1, Q′2, . . . , QN) of encoded modulation symbols for UCI for each transport block, as represented by Q′=Q′1+Q′2+ . . . +Q′N. Q′1 or Q′2 UCI modulation symbols are multiplexed to a layer to which the corresponding codeword is transmitted. If individual transport blocks use different modulation orders, UCI may use a modulation order (QPSK, 16QAM, or 64QAM) of the multiplexed transport block. The following equations 23 and 24 can be modified in the same manner as in Equations 10 to 13.
In Equations 23 and 24, PayloadUCI, PayloadData(1), PayloadData(2), NRe
In the embodiments 2A to 2D, the scope of a codeword where UCI can be multiplexed is not limited according to UCI types. However, ACK/NACK is multiplexed to all codewords, and CSI information such as CQI/PMI can be multiplexed only to a specific codeword as shown in the embodiments 1A to 1C.
The above-mentioned description does not disclose the upper limit and/or the lower limit used for calculating the number of encoded symbols (See the part (2) of Equation 1), for convenience of description and better understanding of the present invention. For example, after the number of finally determined encoded symbols is calculated through Equations 4 to 24, the upper limit and/or the lower limit can be restricted in the same manner as in Equation 1.
For convenience of description and better understanding of the present invention, the above-mentioned description has disclosed that the number (Q′) of encoded symbols for UCI is set to a total number of all symbols. In this case, QUCI=Q′UCI(total)·Qm is obtained. QUCI is a total number of encoded bits for UCI, Q′UCI(total) is a total number of encoded symbols for UCI. Qm is a modulation order. In this case, the equation for calculating Q′UCI includes parameters related to the number of layers as shown in the above-mentioned equations. On the other hand, according to implementation methods, the number (Q′) of encoded symbols for UCI may be determined on the basis of each layer. In this case, QUCI=L·Q′UCI(layer)·Qm is obtained. In this case, L is the number of layers where UCI is multiplexed (differently, the number of layers mapped to a UCI-related transport block), Q′UCI(layer) is the number of encoded symbols for UCI for each layer. Q′UCI(layer) is obtained by setting each of all the layer-related parameters shown in the above-mentioned equations to 1.
Referring to
The aforementioned embodiments are achieved by combination of structural elements and features of the present invention in a predetermined type. Each of the structural elements or features should be considered selectively unless specified separately. Each of the structural elements or features may be carried out without being combined with other structural elements or features. Also, some structural elements and/or features may be combined with one another to constitute the embodiments of the present invention. The order of operations described in the embodiments of the present invention may be changed. Some structural elements or features of one embodiment may be included in another embodiment, or may be replaced with corresponding structural elements or features of another embodiment. Moreover, it will be apparent that some claims referring to specific claims may be combined with another claims referring to the other claims other than the specific claims to constitute the embodiment or add new claims by means of amendment after the application is filed.
The embodiments of the present invention have been described based on the data transmission and reception between the base station and the user equipment. A specific operation which has been described as being performed by the base station may be performed by an upper node of the base station as the case may be. In other words, it will be apparent that various operations performed for communication with the user equipment in the network which includes a plurality of network nodes along with the base station can be performed by the base station or network nodes other than the base station. The base station may be replaced with terms such as a fixed station, Node B, eNode B (eNB), and access point. Also, the user equipment may be replaced with terms such as mobile station (MS) and mobile subscriber station (MSS).
The embodiments according to the present invention can be implemented by various means, for example, hardware, firmware, software, or their combination. If the embodiment according to the present invention is implemented by hardware, the embodiment of the present invention can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.
If the embodiment according to the present invention is implemented by firmware or software, the embodiment of the present invention may be implemented by a type of a module, a procedure, or a function, which performs functions or operations described as above. Software code may be stored in a memory unit and then may be driven by a processor. The memory unit may be located inside or outside the processor to transmit and receive data to and from the processor through various means which are well known.
It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the invention. Thus, the above embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all change which comes within the equivalent scope of the invention are included in the scope of the invention.
Various embodiments have been described in the best mode for carrying out the invention.
Exemplary embodiments of the present invention can be applied to a wireless communication system such as a UE, a relay and a BS.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Number | Date | Country | Kind |
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10-2011-0030166 | Apr 2011 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR2011/002634 | 4/13/2011 | WO | 00 | 7/20/2012 |
Number | Date | Country | |
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61323843 | Apr 2010 | US | |
61324291 | Apr 2010 | US | |
61366909 | Jul 2010 | US | |
61369080 | Jul 2010 | US |