Direct transport block size specification

Certain aspects of the present disclosure provide techniques for wireless communication. An exemplary method generally includes receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determining, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmitting the information using the MCS and TBS.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for direct transport block size specification.

DESCRIPTION OF RELATED ART

BRIEF SUMMARY

Certain aspects provide a method for wireless communication. The method generally includes receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determining, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmitting the information using the MCS and TBS.

Certain aspects provide an apparatus for wireless communication. The apparatus generally includes at least one processor configured to receive an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determine, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmit the information using the MCS and TBS. The apparatus also generally includes a memory coupled with the at least one processor.

Certain aspects provide an apparatus for wireless communication. The apparatus generally includes means for receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, means for determining, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and means for transmitting the information using the MCS and TBS.

Certain aspects provide a non-transitory computer-readable medium for wireless communication. The non-transitory computer-readable medium generally includes instructions that, when executed by at least one processor, cause the at least one processor to receive an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determine, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmit the information using the MCS and TBS.

Certain aspects provide a method for wireless communication. The method generally includes transmitting an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, transmitting an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and receiving the information transmitted using the MCS and TBS.

Certain aspects provide an apparatus for wireless communication. The apparatus generally includes at least one processor configured to transmit an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, transmit an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and receive the information transmitted using the MCS and TBS. The apparatus also generally includes a memory coupled with the at least one processor.

Certain aspects provide an apparatus for wireless communication. The apparatus generally includes means for transmitting an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, means for transmitting an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and means for receiving the information transmitted using the MCS and TBS.

Certain aspects provide a non-transitory computer-readable medium for wireless communication. The non-transitory computer-readable medium generally includes instructions that, when executed by at least one processor, cause the at least one processor to transmit an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, transmit an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and receive the information transmitted using the MCS and TBS.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for direct transport block size (TBS) specification. For example, in LTE, transport block size (TBS) may be calculated based on a TBS index from a modulation and coding scheme (MCS) lookup table and another lookup table based on allocated resources. In 5G NR, TBS may be calculated based on allocated resources, modulation order, and target coding rates. However, as a result, in some cases, it can be more difficult to achieve a desired TBS in 5G NR than in LTE due to spectral efficiency.

Thus, aspects of the present disclosure provide techniques for achieving a desired TBS in 5G NR without compromising performance or scheduler flexibility (e.g., MCS entries and/or spectral efficiency and resource allocation that may be used to reach a desired/target TBS). For example, unlike LTE which keeps the spectral efficiency relatively the same within an MCS index value, aspects of the present disclosure propose techniques to achieve a desired TBS with variable spectral efficiency.

The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS).

New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Example Wireless Communications System

FIG. 1illustrates an example wireless communication network100. According to aspects presented herein, the wireless communications network may be a may be a New Radio (NR) or 5G network in which aspects provided herein may be practiced. For example, in some cases, techniques for achieving a desired TBS in 5G NR without compromising performance or scheduler flexibility, as described below, may be practiced by one or more of the base stations or user equipments disclosed inFIG. 1. In some cases, achieving a desired TBS in 5G NR without compromising performance or scheduler flexibility may involve defining a new type of MCS entry in an MCS lookup table that explicitly indicate a desired TBS to be used by a base station and/or user equipment when transmitting information.

As illustrated inFIG. 1, the wireless communication network100may include a number of base stations (BSs)110and other network entities. ABS may be a station that communicates with user equipments (UEs). Each BS110may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB), new radio base station (NR BS), 5G NB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network100through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

FIG. 2illustrates an example logical architecture of a distributed Radio Access Network (RAN)200, which may be implemented in the wireless communication network100illustrated inFIG. 1. A 5G access node206may include an access node controller (ANC)202. ANC202may be a central unit (CU) of the distributed RAN200. The backhaul interface to the Next Generation Core Network (NG-CN)204may terminate at ANC202. The backhaul interface to neighboring next generation access Nodes (NG-ANs)210may terminate at ANC202. ANC202may include one or more transmission reception points (TRPs)208(e.g., cells, B Ss, gNBs, etc.).

The TRPs208may be a distributed unit (DU). TRPs208may be connected to a single ANC (e.g., ANC202) or more than one ANC (not illustrated). For example, for RAN sharing, radio as a service (RaaS), and service specific AND deployments, TRPs208may be connected to more than one ANC. TRPs208may each include one or more antenna ports. TRPs208may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE.

The logical architecture of distributed RAN200may support fronthauling solutions across different deployment types. For example, the logical architecture may be based on transmit network capabilities (e.g., bandwidth, latency, and/or jitter).

The logical architecture of distributed RAN200may share features and/or components with LTE. For example, next generation access node (NG-AN)210may support dual connectivity with NR and may share a common fronthaul for LTE and NR.

The logical architecture of distributed RAN200may enable cooperation between and among TRPs208, for example, within a TRP and/or across TRPs via ANC202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logical architecture of distributed RAN200. As will be described in more detail with reference toFIG. 5, the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and a Physical (PHY) layers may be adaptably placed at the DU (e.g., TRP208) or CU (e.g., ANC202).

FIG. 3illustrates an example physical architecture of a distributed Radio Access Network (RAN)300, according to aspects of the present disclosure. A centralized core network unit (C-CU)302may host core network functions. C-CU302may be centrally deployed. C-CU302functionality may be offloaded (e.g., to advanced wireless services (AWS)), in an effort to handle peak capacity.

A centralized RAN unit (C-RU)304may host one or more ANC functions. Optionally, the C-RU304may host core network functions locally. The C-RU304may have distributed deployment. The C-RU304may be close to the network edge.

FIG. 4illustrates example components of BS110and UE120(as depicted inFIG. 1), which may be used to implement aspects of the present disclosure. For example, antennas452, processors466,458,464, and/or controller/processor480of the UE120and/or antennas434, processors420,480,438, and/or controller/processor440of the BS110may be used to perform the various techniques and methods described herein.

The controllers/processors440and480may direct the operation at the base station110and the UE120, respectively. The processor440and/or other processors and modules at the BS110may perform or direct the execution of processes for the techniques described herein. The memories442and482may store data and program codes for BS110and UE120, respectively. A scheduler444may schedule UEs for data transmission on the downlink and/or uplink.

FIG. 5illustrates a diagram500showing examples for implementing a communications protocol stack, according to aspects of the present disclosure. The illustrated communications protocol stacks may be implemented by devices operating in a wireless communication system, such as a 5G system (e.g., a system that supports uplink-based mobility). Diagram500illustrates a communications protocol stack including a Radio Resource Control (RRC) layer510, a Packet Data Convergence Protocol (PDCP) layer515, a Radio Link Control (RLC) layer520, a Medium Access Control (MAC) layer525, and a Physical (PHY) layer530. In various examples, the layers of a protocol stack may be implemented as separate modules of software, portions of a processor or ASIC, portions of non-collocated devices connected by a communications link, or various combinations thereof. Collocated and non-collocated implementations may be used, for example, in a protocol stack for a network access device (e.g., ANs, CUs, and/or DUs) or a UE.

A second option505-bshows a unified implementation of a protocol stack, in which the protocol stack is implemented in a single network access device. In the second option, RRC layer510, PDCP layer515, RLC layer520, MAC layer525, and PHY layer530may each be implemented by the AN. The second option505-bmay be useful in, for example, a femto cell deployment.

Regardless of whether a network access device implements part or all of a protocol stack, a UE may implement an entire protocol stack as shown in505-c(e.g., the RRC layer510, the PDCP layer515, the RLC layer520, the MAC layer525, and the PHY layer530).

In LTE, the basic transmission time interval (TTI) or packet duration is the 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing. The NR RB is 12 consecutive frequency subcarriers. NR may support a base subcarrier spacing of 15 KHz and other subcarrier spacing may be defined with respect to the base subcarrier spacing, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing.

FIG. 6is a diagram showing an example of a frame format600for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the subcarrier spacing. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols).

In NR, a synchronization signal (SS) block is transmitted. The SS block includes a PSS, a SSS, and a two symbol PBCH. The SS block can be transmitted in a fixed slot location, such as the symbols0-3as shown inFIG. 6. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS blocks may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI), system information blocks (SIBs), other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes.

Example Error Correction Coding

Many communications systems use error-correcting codes. Specifically, error-correcting codes compensate for the intrinsic unreliability of information transfer in these systems by introducing redundancy into the data stream. Low-density parity check (LDPC) codes are a particular type of error correcting codes which use an iterative coding system. In particular, Gallager codes are an early example of regular LDPC codes. LDPC codes are linear block codes in which most of the elements of its parity check matrix H are set to ‘0’.

LDPC codes can be represented by bipartite graphs (often referred to as “Tanner graphs”), wherein a set of variable nodes corresponds to bits of a code word (e.g., information bits or systematic bits), and a set of check nodes correspond to a set of parity-check constraints that define the code. Edges in the graph connect variable nodes to check nodes. Thus, the nodes of the graph are separated into two distinctive sets, variable nodes and check nodes, with edges connecting the two different types of nodes.

A lifted graph is created by copying a bipartite base graph (G), which may also be known as a protograph, a number of times, Z. A variable node and a check node may be considered “neighbors” if they are connected by an “edge” (i.e., the line connecting the variable node and the check node) in the graph. In addition, for each edge (e) of the bipartite base graph (G), a permutation is applied to the Z copies of edge (e) to interconnect the Z copies of G. A bit sequence having a one-to-one association with the variable node sequence is a valid codeword if, and only if, for each check node, the bits associated with all neighboring variable nodes sum to zero modulo two (i.e., they include an even number of 1's). The resulting LDPC code may be quasi-cyclic (QC) if the permutations used are cyclic.

FIGS. 7-7Ashow graphical and matrix representations of an exemplary LDPC code, in accordance with certain aspects of the present disclosure. For example,FIG. 7shows a bipartite graph700representing an exemplary LDPC code. The bipartite graph700includes a set of 5 variable nodes710(represented by circles) connected to 4 check nodes720(represented by squares). Edges in the graph bipartite700connect variable nodes710to the check nodes720(represented by the lines connecting the variable nodes710to the check nodes720). This graph consists of |V|=5 variable nodes and |C|=4 check nodes, connected by |E|=12 edges.

The bipartite graph may be represented by a simplified adjacency matrix, which may also be known as a parity check matrix.FIG. 7Ashows a matrix representation700A of the bipartite graph700. The matrix representation700A includes a parity check matrix H and a code word vector x, where x1-x5 represent bits of the code word x. The parity matrix H is used for determining whether a received signal was normally decoded. The parity check matrix H has C rows corresponding to j check nodes and V columns corresponding to i variable nodes (i.e., a demodulated symbol), where the rows represent the equations and the columns represents the bits of the code word. InFIG. 7A, matrix H has 4 rows and 5 columns corresponding to 4 check nodes and 5 variable nodes respectfully. If a j-th check node is connected to an i-th variable node by an edge, i.e., the two nodes are neighbors, then there is a 1 in the i-th column and in the j-th row of the parity check matrix H. That is, the intersection of an i-th row and a j-th column contains a “1” where an edge joins the corresponding vertices and a “0” where there is no edge. The code word vector x represents a valid code word if, and only if, Hx=0 (e.g., if, for each constraint node, the bits neighboring the constraint (via their association with variable nodes) sum to zero modulo two, i.e., they comprise an even number of ones). Thus, if the code word is received correctly, then Hx=0 (mod2). When the product of a coded received signal and the parity check matrix H becomes ‘0’, this signifies that no error has occurred. The parity check matrix is a C row by V column binary matrix. The rows represent the equations and the columns represent the digits in the code word.

The number of demodulated symbols or variable nodes is the LDPC code length. The number of non-zero elements in a row (column) is defined as the row (column) weight dc (dv).

The degree of a node refers to the number of edges connected to that node. This feature is illustrated in the H matrix shown inFIG. 7Awhere the number of edges incident to a variable node710is equal to the number of 1's in the corresponding column and is called the variable node degree d(v). Similarly, the number of edges connected with a check node720is equal to the number of ones in a corresponding row and is called the check node degree d(c).

A regular graph or code is one for which all variable nodes have the same degree, j, and all constraint nodes have the same degree, k. In this case, we say that the code is a (j, k) regular code. On the other hand, an irregular code has constraint nodes and/or variable nodes of differing degrees. For example, some variable nodes may be of degree 4, others of degree 3 and still others of degree 2.

“Lifting” enables LDPC codes to be implemented using parallel encoding and/or decoding implementations while also reducing the complexity typically associated with large LDPC codes. Lifting helps enable efficient parallelization of LDPC decoders while still having a relatively compact description. More specifically, lifting is a technique for generating a relatively large LDPC code from multiple copies of a smaller base code. For example, a lifted LDPC code may be generated by producing Z number of parallel copies of a base graph (e.g., protograph) and then interconnecting the parallel copies through permutations of edge bundles of each copy of the base graph. The base graph defines the (macro) structure of the code and consists of a number (K) of information bit-columns and a number (N) of code bit columns. Lifting the base graph a number (Z) of results in a final block length of KZ.

Thus, a larger graph can be obtained by a “copy and permute” operation where multiple copies of the base graph are made and connected to form a single lifted graph. For the multiple copies, like edges that are a set of copies of a single base edge, are permutated and connected to form a connected graph Z times larger than the base graph.

FIG. 8graphically illustrates the effect of making three copies800of the graph ofFIG. 7. Three copies may be interconnected by permuting like edges among the copies. If the permutations are restricted to cyclic permutations, then the resulting graph corresponds to a quasi-cyclic LDPC with lifting Z=3. The original graph from which three copies were made is referred to herein as the base graph. To obtain derived graphs of different sizes, we can apply the “copy and permute” operation to a base graph.

A corresponding parity check matrix of the lifted graph can be constructed from the parity check matrix of the base graph by replacing each entry in the base parity check matrix with a Z×Z matrix. The 0 entries (those having no base edges) are replaced with the 0 matrix and the 1 entries (indicating a base edge) are replaced with a Z×Z permutation matrix. In the case of cyclic liftings the permutations are cyclic permutations.

A cyclically lifted LDPC code can also be interpreted as a code over the ring of binary polynomials modulo xZ+1. In this interpretation, a binary polynomial, (x)=b0+b1x+b2x2+bZ-1xZ-1may be associated to each variable node in the base graph. The binary vector (b0, b1, b2, . . . , bZ-1) corresponds to the bits associated to Z corresponding variable nodes in the lifted graph, that is, Z copies of a single base variable node. A cyclic permutation by k of the binary vector is achieved by multiplying the corresponding binary polynomial by xkwhere multiplication is taken modulo xZ+1. A degree d parity check in the base graph can be interpreted as a linear constraint on the neighboring binary polynomials B1(x), . . . , Bd(X) written as xk1B1(x)+xk2B2(x)+ . . . +xkdBd(x)=0 where the values, kdare the cyclic lifting values associated to the corresponding edges.

This resulting equation is equivalent to the Z parity checks in the cyclically lifted Tanner graph corresponding to the single associated parity check in the base graph. Thus, the parity check matrix for the lifted graph can be expressed using the matrix for the base graph in which 1 entries are replaced with monomials of the form xkand 0 entries are lifted as 0, but now the 0 is interpreted as the 0 binary polynomial modulo xZ+1. Such a matrix may be written by giving the value kin place of xk. In this case the 0 polynomial is sometimes represented as −1 and sometimes as another character in order to distinguish it from x0.

Typically, a square submatrix of the parity check matrix represents the parity bits of the code. The complementary columns correspond to information bits that, at the time of encoding, are set equal to the information bits to be encoded. The encoding may be achieved by solving for the variables in the aforementioned square submatrix in order to satisfy the parity check equations. The parity check matrix H may be partitioned into two parts M and N where M is the square portion. Thus, encoding reduces to solving Mc=s=Nd where c and d comprise x. In the case of quasi-cyclic codes, or cyclically lifted codes, the above algebra can be interpreted as being over the ring of binary polynomials modulo xZ+1. In the case of the 802.11 LDPC codes, which are quasi-cyclic, the encoding submatrix M has an integer representation900as shown inFIG. 9.

A received LDPC code word can be decoded to produce a reconstructed version of the original code word. In the absence of errors, or in the case of correctable errors, decoding can be used to recover the original data unit that was encoded. Redundant bits may be used by decoders to detect and correct bit errors. LDPC decoder(s) generally operate by iteratively performing local calculations and passing those results by exchanging messages within the bipartite graph700, along the edges, and updating these messages by performing computations at the nodes based on the incoming messages. These steps may typically be repeated several times and may be referred to as message passing steps. For example, each variable node710in the graph700may initially be provided with a “soft bit” (e.g., representing the received bit of the code word) that indicates an estimate of the associated bit's value as determined by observations from the communications channel. Using these soft bits the LDPC decoders may update messages by iteratively reading them, or some portion thereof, from memory and writing an updated message, or some portion thereof, back to, memory. The update operations are typically based on the parity check constraints of the corresponding LDPC code. In implementations for lifted LDPC codes, messages on like edges are often processed in parallel.

LDPC codes designed for high speed applications often use quasi-cyclic constructions with large lifting factors and relatively small base graphs to support high parallelism in encoding and decoding operations. LDPC codes with higher code rates (e.g., the ratio of the message length to the code word length) tend to have relatively fewer parity checks. If the number of base parity checks is smaller than the degree of a variable node (e.g., the number of edges connected to a variable node), then, in the base graph, that variable node is connected to at least one of the base parity checks by two or more edges (e.g., the variable node may have a “double edge”). Or if the number of base parity checks is smaller than the degree of a variable node (e.g., the number of edges connected to a variable node), then, in the base graph, that variable node is connected to at least one of the base parity checks by two or more edges. Having a base variable node and a base check node connected by two or more edges is generally undesirable for parallel hardware implementation purposes. For example, such double edges may result in multiple concurrent read and write operations to the same memory locations, which in turn may create data coherency problems. A double edge in a base LDPC code may trigger parallel reading of the same soft bit value memory location twice during a single parallel parity check update. Thus, additional circuitry is typically needed to combine the soft bit values that are written back to memory, so as to properly incorporate both updates. However, eliminating double edges in the LDPC code helps to avoid this extra complexity

LDPC code designs based on cyclic lifting can be interpreted as codes over the ring of polynomials modulo may be binary polynomials modulo xZ+1, where Z is the lifting size (e.g., the size of the cycle in the quasi-cyclic code). Thus encoding such codes can often be interpreted as an algebraic operation in this ring.

In the definition of standard irregular LDPC code ensembles (degree distributions) all edges in the Tanner graph representation may be statistically interchangeable. In other words, there exists a single statistical equivalence class of edges. A more detailed discussion of lifted LDPC codes may be found, for example, in the book titled, “Modern Coding Theory,” published Mar. 17, 2008, by Tom Richardson and Ruediger Urbanke.

For multi-edge LDPC codes, multiple equivalence classes of edges may be possible. While in the standard irregular LDPC ensemble definition, nodes in the graph (both variable and constraint) are specified by their degree, i.e., the number of edges they are connected to, in the multi-edge type setting an edge degree is a vector; it specifies the number of edges connected to the node from each edge equivalence class (type) independently. A multi-edge type ensemble is comprised of a finite number of edge types. The degree type of a constraint node is a vector of (non-negative) integers; the i-th entry of this vector records the number of sockets of the i-th type connected to such a node. This vector may be referred to as an edge degree. The degree type of a variable node has two parts although it can be viewed as a vector of (non-negative) integers. The first part relates to the received distribution and will be termed the received degree and the second part specifies the edge degree. The edge degree plays the same role as for constraint nodes. Edges are typed as they pair sockets of the same type. This constraint—that sockets must pair with sockets of like type—characterizes the multi-edge type concept. In a multi-edge type description, different node types can have different received distributions (e.g., the associated bits may go through different channels).

FIG. 10illustrates a portion of a radio frequency (RF) modem1004that may be configured to provide an encoded message for wireless transmission. In one example, an encoder1006in a base station (e.g., Node B102and/or transmitter system210) (or wireless node on the reverse path) receives a message1002for transmission. The message1002may contain data and/or encoded voice or other content directed to the receiving device. The encoder1006encodes the message using a suitable modulation and coding scheme (MCS), typically selected based on a configuration defined by the base station or another network entity. In some cases, the encoder1006may encode the message, for example, using techniques described above (e.g., by using a LDPC code). An encoded bitstream1008produced by the encoder1006may then be provided to a mapper1010that generates a sequence of Tx symbols1012that are modulated, amplified and otherwise processed by Tx chain1014to produce an RF signal1016for transmission through antenna1018.

FIG. 11illustrates a portion of a RF modem that may be configured to receive and decode a wirelessly transmitted signal including an encoded message (e.g., a message encoded using a LDPC code as described above). In various examples, the RF modem receiving the signal may reside at the wireless node (e.g., user equipment120), at the base station (e.g., Node B110), or at any other suitable apparatus or means for carrying out the described functions. An antenna1102receives an RF signal1116(i.e., the RF signal1116produced inFIG. 11) for a wireless node (e.g., user equipment120). An RF chain1104processes and demodulates the RF signal1116and may provide a sequence of demodulated symbols1106to a demapper1108, which produces a bitstream1110representative of the encoded message.

A decoder1112may then be used to decode m-bit information strings from a bitstream that has been encoded using a coding scheme (e.g., an LDPC code). The decoder1112may comprise a layered LDPC decoder with a full-parallel, row-parallel, or block-parallel architecture. LDPC decoder(s) generally operate by iteratively performing local calculations and passing those results by exchanging messages within the bipartite graph700, along the edges, and updating these messages by performing computations at the nodes based on the incoming messages. These steps may typically be repeated several times and may be referred to as message passing steps. For example, each variable node710in the graph700may initially be provided with a “soft bit” (e.g., representing the received bit of the code word) that indicates an estimate of the associated bit's value as determined by observations from the communications channel. The “soft bit” may be represented by a log-likelihood ratio (LLR) that in some aspects may be defined as the log((probability the bit is 0)/(probability the bit is 1)). Using these LLRs the LDPC decoders may update messages by iteratively reading them, or some portion thereof, from memory and writing an updated message, or some portion thereof, back to, memory. The update operations are typically based on the parity check constraints of the corresponding LDPC code. In implementations for lifted LDPC codes, messages on like edges are often processed in parallel. According to aspects, following these decoding techniques, the decoder1112may decode the bitstream1110based on the LLRs to determine the message1002containing data and/or encoded voice or other content transmitted from the base station (e.g., Node B110). The decoder may decode the bitstream1110in accordance with aspects of the present disclosure presented below.

Example Direct Transport Block Size Specification

In LTE, transport block size (TBS) is calculated based on a TBS index from a modulation and coding scheme (MCS) lookup table and another lookup table based on allocated resources. In 5G NR, TBS may be calculated based on allocated resources, modulation order, and target coding rates. As a result, in some cases, it can be more difficult to achieve a desired TBS in 5G NR than in LTE due to spectral efficiency. Additionally, in 5G NR for ultra reliable low-latency communication (URLLC) transmissions (and potentially other scenarios), some TBS values may be expected to be dominant (e.g., 32 bits may be dominant in an industrial employment).

In 5G NR, there are two types of MCS entries in the MCS lookup table in NR, namely explicit MCS and implicit (e.g., reserved) MCS. Explicit MCS entries specify a modulation order and a target coding rate, while implicit MCS entries only specify a modulation order. In some cases, implicit MCS entries may be used when performing a re-transmission of a TB and indicate that the same TBS from a previous transmission is used for the retransmission of the same transport block (TB).

In some cases, it may be difficult or even impossible to reach a particular TBS given certain scheduling constraints, such as an exact number of resource elements with an exact MCS. For example, if the exact number of REs needed for transmission with the exact MCS cannot be allocated, a desired TBS may not be attainable. Additionally, padding the transport block from the media access control (MAC) layer, may degrade performance. Further, there are a limited number of MCS values—some of which may not support certain TBS. Additionally, implicit MCS entries cannot be used for initial transmission, thus restricting certain TBSs.

Thus, aspects of the present disclosure provide techniques for achieving a desired TBS in 5G NR without compromising performance or scheduler flexibility (e.g., MCS entries and/or spectral efficiency and resource allocation that may be used to reach a desired/target TBS). For example, unlike LTE which keeps the spectral efficiency relatively the same within an MCS index value, aspects of the present disclosure propose techniques to achieve a desired TBS with variable spectral efficiency. In some cases, achieving such results may involve defining a new type of MCS entry in the MCS lookup table that explicitly indicate a desired TBS (e.g., rather than having to calculate the TBS).

FIG. 12illustrates example operations1200for wireless communication in a network, according to certain aspects of the present disclosure. According to aspects, Operations1200may be performed by a wireless communications device (e.g., UE120and/or BS110).

The wireless communications device may include one or more components as illustrated inFIG. 4, which may be configured to perform operations1200described herein. For example, the antenna434, modulator/demodulator432, transmit processor420, controller/processor440, and/or memory442of the base station110, as illustrated inFIG. 4, may perform operations1200described herein. Additionally or alternatively, the antenna452, demodulator/modulator454, transmit processor464, controller/processor480, and/or memory482of the user equipment120, as illustrated inFIG. 4, may perform operations1200described herein.

Operations1200begin at1202by receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table.

At1204, the wireless communications device determines, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information.

At1206, the wireless communications device transmits the information using the MCS and TBS.

FIG. 13illustrates example operations1300for wireless communication in a network, according to certain aspects of the present disclosure. According to aspects, Operations1300may be performed by a wireless communications device (e.g., UE120and/or BS110).

The wireless communications device may include one or more components as illustrated inFIG. 4, which may be configured to perform operations1300described herein. For example, the antenna434, modulator/demodulator432, transmit processor420, controller/processor440, and/or memory442of the base station110, as illustrated inFIG. 4, may perform operations1300described herein. Additionally or alternatively, the antenna452, demodulator/modulator454, transmit processor464, controller/processor480, and/or memory482of the user equipment120, as illustrated inFIG. 4, may perform operations1300described herein.

Operations1300begin at1302by transmitting an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table.

At1304, the wireless communications device transmits an explicit indication of the TB S to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value.

At1306, the wireless communications device receives the information transmitted using the MCS and TBS.

As noted above, aspects of the present disclosure propose techniques to achieve a desired TBS with variable spectral efficiency, unlike LTE which keeps the spectral efficiency relatively the same within an MCS index value. In some cases, achieving such results may involve defining a new type of MCS entry in the MCS lookup table (e.g., known as Explicit-TBS entries) that explicitly indicate a desired TBS (e.g., rather than having to calculate the TBS). According to aspects, in some cases, these Explicit-TBS entries may not explicitly define a coding rate to use when transmitting information.

For example, in some cases, a base station may transmit an indication of a MCS to use for transmitting information. According to aspects this MCS indication may indicate an MCS index value corresponding to an entry in an MCS lookup table. In some cases, the MCS index value may correspond to an Explicit-TBS entry in the MCS lookup table, indicating to a user equipment a particular TBS to use for transmitting the information. For example, in one case, a base station may transmit a message indicating an MCS index value (e.g., MCS28) that corresponds to an Explicit-TBS entry in the MCS lookup table. At the user equipment, the user equipment may then use the MCS index value to determine a TBS to use for transmission of the information, as described below.

As noted, the MCS index value may correspond to an Explicit-TBS MCS entry in the MCS lookup table. In some cases, the user equipment may determine the TBS using a TBS lookup table and the MCS value indicated by the Explicit-TBS MCS entry value (e.g., using the MCS value to look up the TBS in the TBS lookup table). In other cases, the Explicit-TBS MCS value may indicate to the user equipment that the user equipment is to receive a message comprising an explicit indication of the TBS. For example, in some cases, the user equipment may receive the explicit indication of the TBS in a radio resource control (RRC) message from the network, downlink control information (DCI), a media access control-control element (MAC-CE) from the network, and/or in a semi-persistent scheduling configuration (SPS) message from the network.

According to aspects, Explicit-TBS MCS entries can be configured as in the dynamic scheduling cases and, for activation-based SPS, the TBS value (direct TBS configuration and/or explicit-TBS MCS) can be activated/deactivated. For example, in some cases, the MCS index may be included in a DCI activating SPS message that activates the SPS process. Additionally, in some cases, an explicit indication of the TBS may be RRC configured, for example, in an SPS RRC configuration.

Additionally, in some cases, a modulation order (e.g., that indicates to the UE a modulation method (e.g., QPSK, 16 QAM, 64 QAM, 256 QAM, etc) to be used) can be explicitly defined for each Explicit-TBS MCS entry in the MCS lookup table. Further, according to aspects, an indication of the modulation order may be received in an RRC message, DCI, and/or MAC-CE from the network.

In some cases, the explicit indication of the TBS may be indicated as a number of bits (e.g., a transport block size in a number of bits). According to aspects, when indicated as a number of bits, the TBS can be any value or only values that are already valid TBSs from the TBS determination procedure. In other cases, the explicit indication of the TBS may be indicated as a TBS index value in a TBS lookup table. For example, the user equipment may use the TBS index value to look up the explicit TBS in the TBS lookup table. According to aspects, this TBS lookup table may be different from LTE in that, with the proposed TBS lookup table, there is a one-to-one mapping between the TBS and TBS index, whereas a TBS index in conjunction with a number of allocated RBs was used to determine the TBS.

As noted previously, the MCS lookup table may comprise entries for explicit MCS values, implicit MCS values, and explicit-TBS MCS values. In some cases, the MCS lookup table may comprise dedicated MCS entries for each type of MCS value. That is, in some cases, the MCS lookup table may comprise distinct entries for explicit MCS values, distinct entries for implicit MCS values, and distinct entries for explicit-TBS MCS values.

In other cases, the MCS lookup table may comprise entries that are shared among two or more MCS types. For example, in some cases, explicit TBS MCS values and implicit MCS values may share the same indices (e.g., entries) in the MCS lookup table. In such a case, a user equipment may need to know how to distinguish between explicit-TB S MCS values and implicit MCS values. To distinguish between the type of MCS values when MCS values share the same entries in the MCS table, the user equipment may look to see whether an explicit TBS has been configured by the network or not. For example, if the user equipment has received a message (e.g., RRC, MAC-CE, DCI, and/or SPS activating message) indicating an explicit TBS (e.g., an explicit TBS is configured), the user equipment may assume that the MCS index value corresponds to an explicit-TBS MCS value. However, if the user equipment has not received a message indicating an explicit TBS (e.g., an explicit TBS is not configured), the user equipment may assume that the MCS index value corresponds to an implicit MCS value. Additionally, in some cases, the user equipment may assume the MCS index value corresponds to an implicit MCS value when the user equipment receives a message indicating an explicit TBS and the indicated explicit TBS is set to a special value (e.g., zero or all ones, etc.).

In some cases, explicit-TBS entries may share the same MCS indices in the MCS lookup table with both explicit MCS values and implicit MCS values. In such a case, the user equipment may determine whether the MCS index value corresponds to an explicit MCS value, an implicit MCS value, or an explicit-TBS MCS value using similar techniques as presented above. For example, if an explicit TBS is not configured, the entries in the MCS lookup table and their values may be assumed to be either explicit or implicit MCS entries as defined in the MCS lookup table. For example, if the particular MCS index value corresponds to an entry in the MCS lookup table where explicit MCS value typically is located and when an explicit TBS is not configured, the user equipment may assume that the MCS index value corresponds to an explicit MCS value. According to aspects, when an explicit MCS value is configured, the user equipment may assume that the MCS index value corresponds to an explicit-TBS MCS value. Additionally, in some cases, if an explicit TBS is configured to a special value (e.g. zero or all-ones, etc.), the user equipment may assume the MCS index value corresponds to either explicit or implicit MCS entries as defined in the table.

According to aspects, when transmitting information across a wireless channel, this information may need to be encoded, for example, using a low-density parity check (LPDC) code, as described above. In some cases, in order to encode information using an LDPC code, a user equipment may first have to make a determination of the LDPC base-graph to use to perform the encoding. This determination is traditionally based, at least in part, on a target code rate. However, when using explicitly-indicated TBSs for a first transmission, it may not be clear how to determine the LDPC base-graph since explicit-TBS MCS entries may lack an explicitly-defined target code rate.

According to aspects, to resolve the issue with determining the LDPC base-graph, aspects of the present disclosure propose techniques whereby, in some cases, the base-graph may be determined based on the TBS for explicit-TBS MCS entries. In such a case, all explicit-TBS MCS entries may share the same base-graph configuration or each entry may correspond to a unique base-graph configuration (e.g., each entry may correspond with its own base-graph configuration). Additionally, in some cases, a first group of explicit-TBS MCS entries may share a first LDPC base-graph configuration while a second group of explicit-TB S MCS entries may share a second LDPC base-graph configuration.

In other cases, an indication of a base-graph and/or base-graph configuration to use for a corresponding explicit-TB S MCS value may be fixed in a standards document and looked up by the user equipment. In such case, a single base-graph and/or base-graph configuration may correspond to all explicit-TB S MCS entries or subsets of MCS indices may be mapped to different base graphs and/or base-graph configurations.

Further, according to aspects, if the explicit-TBS MCS entries overlap with explicit MCS entries, the target code rate from latter may be used for the base-graph determination. For explicit-TBS MCS entries that do not overlap with explicit MCS entries, either the first or second option described above may be used to determine the LDPC base-graph.

According to aspects, once the LDPC base-graph has been determined, the user equipment may encode information (e.g., using the determined LDPC base-graph) and transmit the information using the MCS (e.g., received in the indication from the network) and the explicitly-indicated TBS. For example, the UE may encode information using the determined LDPC base-graph. The UE may then transmit the information according to the MCS and explicitly-indicated TBS.

According to aspects, in addition to or alternatively, a combination of MCS and RB allocation can be used to directly indicate TBS. For example, according to aspects, the combination of an MCS index and an RB allocation in a range or set of values may map to a specific TBS, which can be explicitly defined in a standards document or configured by the network (e.g., using an RRC, DCI, MAC-CE, and/or SPS activating message). According to aspects, the proposed technique is different from LTE since, in LTE, for a given MCS index, each RB allocation yields a unique TBS. However, for techniques provided herein, for a given MCS index, multiple RB allocation values may yield the same TBS.

According to aspects, in some cases, more than one channel coding scheme may be used for a data channel when transmitting the information. For example, in some cases, different channel codes may be used to encode data on a physical downlink shared channel (PDSCH) and/or a physical uplink shared channel (PUSCH). In some cases, the choice of which channel code to use may depend on the TBS and, potentially, on the target code rate.

In such a case, the channel coding scheme may be configured based on an explicit-TBS MCS entry in the MCS lookup table. For example, for explicit-TBS entries, the channel coding scheme may be determined based on the configured TBS value (e.g., the explicitly-indicated TBS) received in a message from the network (e.g., RRC, DCI, MAC-CE, SPS, etc.). In some cases, when an explicitly-indicated TBS value is used to specify the TBS, this TBS may override any other TBSs when determining the channel code for the data channel.

Further, in some cases, when explicit-TBS entries in the MCS lookup table overlap other entries in the MCS lookup table (e.g., as described above), the channel coding scheme may be determined according to the original entries (i.e., the entries in the MCS lookup table that are overlapped by the explicit-TB S MCS entries).

Additionally, in some cases, when explicit-TBS entries in the MCS lookup table overlap other entries in the MCS lookup table (e.g., as described above), the channel coding scheme may be determined according to the explicitly-indicated TBS value as well as a coding rate and modulation of the original entries (i.e., the entries in the MCS lookup table that are overlapped by the explicit-TB S MCS entries).

Additionally or alternatively, the channel coding scheme may be explicitly defined for all or a subset of entries in the MCS table. Further, according to aspects, an indication of the channel coding scheme may be received in an RRC message, a MAC-CE, or DCI from the network.

FIG. 14illustrates a communications device1400that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG. 12. The communications device1400includes a processing system1402coupled to a transceiver1408. The transceiver1408is configured to transmit and receive signals for the communications device1400via an antenna1410, such as the various signal described herein. The processing system1402may be configured to perform processing functions for the communications device1400, including processing signals received and/or to be transmitted by the communications device1400.

The processing system1402includes a processor1404coupled to a computer-readable medium/memory1412via a bus1406. In certain aspects, the computer-readable medium/memory1412is configured to store instructions that when executed by processor1404, cause the processor1404to perform the operations illustrated inFIG. 12, or other operations for performing the various techniques discussed herein.

In certain aspects, the processing system1402further includes a receiver component1414for performing the operations illustrated at1202ofFIG. 12. Additionally, the processing system1402includes a determination component1416for performing the operations illustrated at1204inFIG. 12. Additionally, the processing system1402includes a transmitter component1418for performing the operations illustrated at1206inFIG. 12. The receiver component1414, the determination component1416, and the transmitter component1418may be coupled to the processor1404via bus1406. In certain aspects, receiver component1414, the determination component1416, and the transmitter component1418may be hardware circuits. In certain aspects, the receiver component1414, the determination component1416, and the transmitter component1418may be software components that are executed and run on processor1404.

FIG. 15illustrates a communications device1500that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG. 13. The communications device1500includes a processing system1502coupled to a transceiver1508. The transceiver1508is configured to transmit and receive signals for the communications device1500via an antenna1510, such as the various signal described herein. The processing system1502may be configured to perform processing functions for the communications device1500, including processing signals received and/or to be transmitted by the communications device1500.

The processing system1502includes a processor1504coupled to a computer-readable medium/memory1512via a bus1506. In certain aspects, the computer-readable medium/memory1512is configured to store instructions that when executed by processor1504, cause the processor1504to perform the operations illustrated inFIG. 13, or other operations for performing the various techniques discussed herein.

In certain aspects, the processing system1502further includes a transmitter component1514for performing the operations illustrated at1302and1304ofFIG. 13. Additionally, the processing system1502includes a receiver component1516for performing the operations illustrated at1306inFIG. 13. The transmitter component1514and the receiver component1516may be coupled to the processor1504via bus1506. In certain aspects, the transmitter component1514and the receiver component1516may be hardware circuits. In certain aspects, the transmitter component1514and the receiver component1516may be software components that are executed and run on processor1504.

Example Embodiments

Embodiment 1: A method for wireless communications in a network performed by a wireless communications device, including receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determining, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmitting the information using the MCS and TBS.

Embodiment 2: The method of Embodiment 1, wherein explicit indication of the TBS is received in a radio resource control (RRC) message from the network.

Embodiment 3: The method of Embodiment 1, wherein the explicit indication of the TBS is received in a media access control-control element (MAC-CE) message received from the network.

Embodiment 4: The method of any of Embodiments 1 to 3, wherein the wireless communications device receives the explicit indication of the TBS from a TBS lookup table.

Embodiment 5: The method of any of Embodiments 1 to 4, wherein a modulation order is explicitly defined for each entry in the MCS lookup table and transmitting the information comprises transmitting the information using the modulation order.

Embodiment 6: The method of any of Embodiments 1 to 5, wherein a modulation order is received in a radio resource control (RRC) message received from the network transmitting the information comprises transmitting the information using the modulation order.

Embodiment 7: The method of any of Embodiments 1 to 6, wherein the explicit indication of the TBS indicates the TBS in a number of bits.

Embodiment 8: The method of any of Embodiments 1 to 7, wherein the explicit indication of the TBS indicates an index value corresponding to an entry in a TBS lookup table.

Embodiment 9: The method of any of Embodiments 1 to 8, wherein the MCS lookup table comprises dedicated entries for explicit MCS values, implicit MCS values, and MCS values corresponding to explicitly-indicated TBSs.

Embodiment 10: The method of any of Embodiments 1 to 9, wherein the MCS lookup table comprises entries for explicit MCS values, implicit MCS values, and MCS values corresponding to explicitly-indicated TBSs and the entries for implicit MCS values and the entries for the MCS values corresponding to explicitly-indicated TBSs share one or more of the same entries in the MCS lookup table.

Embodiment 11: The method of Embodiment 10, wherein when an explicitly-indicated TBS is not configured by the network, the shared one or more same entries in the MCS lookup table correspond to implicit MCS values and when the explicitly-indicated TBS is configured by the network, the shared one or more same entries in the MCS lookup table correspond to MCS values corresponding to explicitly-indicated TBSs.

Embodiment 12: The method of Embodiment 11, wherein when an explicitly-indicated TBS is configured by the network and the explicit indication of the TBS corresponds to a special value, the shared one or more same entries in the MCS lookup table correspond to implicit MCS values.

Embodiment 13: The method of any of Embodiments 1 to 9, wherein the MCS lookup table comprises entries for explicit MCS values, implicit MCS values, and MCS values corresponding to explicitly-indicated TBSs and the MCS values corresponding to explicitly-indicated TBSs share one or more of the same entries in the MCS lookup table as the entries for explicit MCS values and entries for the implicit MCS values.

Embodiment 14: The method of any of Embodiments 1 to 13, wherein the explicit indication of the TBS lacks an indication of a target code rate and further comprising determining a low-density parity check (LDPC) base-graph to use for encoding the information based, at least in part, on the explicit indication of the TBS.

Embodiment 15: The method of any of Embodiments 1 to 14, wherein the MCS lookup table comprises entries for explicit MCS values, entries for implicit MCS values, and entries for MCS values corresponding to explicitly-indicated TBSs and one of: each entry for MCS values corresponding to explicitly-indicated TBSs correspond to a same LDPC base-graph configuration; each entry for MCS values corresponding to explicitly-indicated TBSs correspond to a different unique base-graph configuration; or a first group of entries for MCS values corresponding to explicitly-indicated TBSs correspond to a first base-graph configuration and a second group of entries for MCS values corresponding to explicitly-indicated TBSs correspond to a second base-graph configuration.

Embodiment 16: The method of any of Embodiments 1 to 14, wherein the MCS lookup table comprises entries for explicit MCS values, entries for implicit MCS values, and entries for MCS values corresponding to explicitly-indicated TBSs; and when the MCS values corresponding to explicitly-indicated TBSs share the same entries as the explicit MCS values, determining the LDPC base-graph is based further on a target code rate associated with a corresponding explicit MCS value.

Embodiment 17: The method of any of Embodiments 1 to 16, wherein the explicit indication of the TBS is received in a semi-persistent scheduling (SPS) message.

Embodiment 18: The method of any of Embodiments 1 to 17, wherein the explicit indication of the TBS is activated and deactivated according to an SPS configuration.

Embodiment 19: The method of any of Embodiments 1 to 18, further comprising determining the TBS based further on MCS index value and a resource block allocation.

Embodiment 20: The method of any of Embodiments 1 to 19, wherein a combination of the MCS index value and the resource block value map to the determined TBS when the combination is within a certain range.

Embodiment 21: A wireless communications in a network performed by a wireless communications device, including transmitting an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, transmitting an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and receiving the information transmitted using the MCS and TBS.

Embodiment 22: The method of Embodiment 21, wherein the explicit indication of the TBS is transmitted in a radio resource control (RRC) message from the network.

Embodiment 23: The method of Embodiment 21, wherein the explicit indication of the TBS is transmitted in a media access control-control element (MAC-CE) message received from the network.

Embodiment 24: The method of any of Embodiments 21 to 23, wherein the explicit indication of the TBS indicates the TBS in a number of bits.

Embodiment 25: The method of any of Embodiments 21 to 24, wherein the explicit indication of the TBS indicates an index value corresponding to an entry in a TBS lookup table.

Embodiment 26: The method of any of Embodiments 21 to 25, wherein the explicit indication of the TBS is transmitted in a semi-persistent scheduling (SPS) message.

Embodiment 27: The method of any of Embodiments 21 to 26, wherein the explicit indication of the TBS is activated and deactivated according to an SPS configuration.

Embodiment 28: An apparatus for wireless communication in a network performed by a wireless communications device, comprising: at least one processor configured to: receive an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table; determine, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information; and transmit the information using the MCS and TBS; and a memory coupled with the at least one processor.

Embodiment 29: An apparatus for wireless communication in a network performed by a wireless communications device, comprising: at least one processor configured to: transmit an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table; transmit an explicit indication of the TB S to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value; and receive the information transmitted using the MCS and TBS; and a memory coupled with the at least one processor.

Embodiment 30: An apparatus for wireless communication in a network performed by a wireless communications device, comprising means for receiving an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, means for determining, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and means for transmitting the information using the MCS and TBS.

Embodiment 31: An apparatus for wireless communication in a network performed by a wireless communications device, comprising means for transmitting an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, means for transmitting an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and means for receiving the information transmitted using the MCS and TBS.

Embodiment 32: A non-transitory computer-readable medium for wireless communication in a network performed by a wireless communications device, comprising instructions that, when executed by at least one processor, cause the at least one processor to receive an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, determine, based on the MCS index value, a transport block size (TBS) to use for transmitting the information, wherein determining the TBS comprises receiving an explicit indication of the TBS to use for transmitting the information, and transmit the information using the MCS and TBS.

Embodiment 33: A non-transitory computer-readable medium for wireless communication in a network performed by a wireless communications device, comprising instructions that, when executed by at least one processor, cause the at least one processor to transmit an indication of a modulation and coding scheme (MCS) to use for transmitting information, wherein the indication of the MCS indicates an MCS index value corresponding to an entry in an MCS lookup table, transmit an explicit indication of the TBS to use for transmitting the information, wherein the explicit indication of the TBS corresponds to the MCS index value, and receive the information transmitted using the MCS and TBS.