Patent Description:
In some examples, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation or <NUM> network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., a new radio base station (NR BS), a new radio node-B (NR NB), a network node, <NUM> NB, eNB, etc.). A base station or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

<NPL>, discloses that in Next Radio segmentation is performed comparing the Maximum information block length Kmax with the TBS and that different coding schemes are associated with different values of maximum information block length. Especially, coding scheme with low minimum coding rate are associated with low maximum information block length Kmax in order to limit decoding complexity and decoding latency.

<NPL> discusses the potential solutions to support larger maximum TBS and larger PDSCH/PUSCH channel bandwidth.

<NPL>, discusses code segmentation mechanism based on LDPC code for eMBB data channel.

<NPL>, discusses CRC attachment and code block segmentation for eMBB data channel.

Document <CIT> relates to relates to a method and apparatus for determining a Transport Block Size (TBS) in a wireless communication system, and more particularly, to a method and apparatus for determining a TBS table in association with <NUM> QAM.

Document <CIT> relates to a code block segmentation method executed in a base station for transmitting data to a terminal and reducing the performance deterioration, and a base station thereof. For large code block sizes, performance of turbo code deteriorates at high code rate. Therefore, for large code block sizes, channel block segmentation is performed by using an increased number of code blocks. The code block segmentation method can reduce the performance deterioration and divide the code block.

The claimed invention is defined by the independent claims. Further embodiments of the claimed invention are described in the dependent claims. Without limiting the scope of the independent claims, some features will now be discussed briefly.

Certain aspects of the present disclosure generally relate to optimizing transport block delivery using resource based code block segmentation.

NR may support various wireless communication services, such as Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM>), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low latency communications (URLLC).

Aspects of the present disclosure relate to resource-based code block segmentation.

<FIG> illustrates an example wireless network <NUM>, such as a new radio (NR) or <NUM> network, in which aspects of the present disclosure may be performed, for example, for enabling connectivity sessions and internet protocol (IP) establishment, as described in greater detail below.

As illustrated in <FIG>, the wireless network <NUM> may include a number of BSs <NUM> and other network entities. A BS may be a station that communicates with UEs. Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B 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 eNB, Node B, <NUM> NB, AP, NR BS, NR BS, or 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 base station. 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 the wireless network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

A network controller <NUM> may be coupled to a set of BSs <NUM> and provide coordination and control for these BSs. The BSs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered evolved or machine-type communication (MTC) devices or evolved MTC (eMTC) devices. Some UEs may be considered Internet-of-Things (IoT) devices.

For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a 'resource block') may be <NUM> subcarriers (or <NUM>). Consequently, the nominal FFT size may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM> (i.e., <NUM> resource blocks), and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using time division duplex (TDD). A single component carrier bandwidth of <NUM> may be supported. NR resource blocks may span <NUM> sub-carriers with a subcarrier bandwidth of <NUM> over a <NUM> duration. Each radio frame may consist of <NUM> subframes with a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. UL and DL subframes for NR may be as described in more detail below with respect to <FIG>. Alternatively, NR may support a different air interface, other than an OFDM-based. NR networks may include entities such CUs and/or DUs.

As noted above, a RAN may include a CU and DUs. A NR BS (e.g., eNB, <NUM> Node B, Node B, transmission reception point (TRP), access point (AP)) may correspond to one or multiple BSs. NR cells can be configured as access cell (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases DCells may not transmit synchronization signals-in some case cases DCells may transmit SS. NR BSs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine NR BSs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

<FIG> illustrates example components of the BS <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. As described above, the BS may include a TRP. One or more components of the BS <NUM> and UE <NUM> may be used to practice aspects of the present disclosure. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to FIG.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), etc. The data may be for the Physical Downlink Shared Channel (PDSCH), etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. For example, the TX MIMO processor <NUM> may perform certain aspects described herein for RS multiplexing.

For example, MIMO detector <NUM> may provide detected RS transmitted using techniques described herein.

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the BS <NUM> and the UE <NUM>, respectively.

The DL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> may sometimes be referred to as an UL burst, a common UL burst, and/or various other suitable terms. The common UL portion <NUM> may include feedback information corresponding to various other portions of the DL-centric subframe. For example, the common UL portion <NUM> may include feedback information corresponding to the control portion <NUM>. Nonlimiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ indicator, and/or various other suitable types of information. The common UL portion <NUM> may include additional or alternative information, such as information pertaining to random access channel (RACH) procedures, scheduling requests (SRs), and various other suitable types of information. As illustrated in <FIG>, the end of the DL data portion <NUM> may be separated in time from the beginning of the common UL portion <NUM>. One of ordinary skill in the art will understand that the foregoing is merely one example of a DL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

<FIG> is a diagram <NUM> showing an example of an UL-centric subframe. The UL -centric subframe may include a control portion <NUM>. The control portion <NUM> may exist in the initial or beginning portion of the UL-centric subframe. The control portion <NUM> in <FIG> may be similar to the control portion described above with reference to <FIG>. The UL-centric subframe may also include an UL data portion <NUM>. The UL data portion <NUM> may sometimes be referred to as the payload of the UL-centric subframe. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (e.g., UE) to the scheduling entity (e.g., UE or BS). In some configurations, the control portion <NUM> may be a physical DL control channel (PDCCH).

As illustrated in <FIG>, the end of the control portion <NUM> may be separated in time from the beginning of the UL data portion <NUM>. The UL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> in <FIG> may be similar to the common UL portion <NUM> described above with reference to <FIG>. The common UL portion <NUM> may additional or alternative include information pertaining to channel quality indicator (CQI), sounding reference signals (SRSs), and various other suitable types of information. One of ordinary skill in the art will understand that the foregoing is merely one example of an UL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

Aspects of the present disclosure provide a mechanism for code-rate dependent transport block segmentation. As will be described herein, by adjusting segmentation parameters, such as code block size, based on a code rate, code block size may be optimized to achieve a desired result. For example, a smaller code block (CB) size may be selected based on a low code rate to achieve increased coding gain (relative to repeated transmission) when reliability is a priority. On the other hand, when peak data rates are a priority, lower code rates may not be desirable and larger code block sizes may be selected.

As used herein, the term code rate (or information rate) generally refers to the proportion of a data-stream that is useful (non-redundant). That is, if the code rate is k/n, for every k bits of useful information, the coder generates a total of n bits of data, of which n-k are redundant. Thus, the code rate of a convolutional code will typically be <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, or the like, corresponding to one redundant bit inserted after every first, second, third, fourth, fifth, sixth, or seventh bit, respectively.

Using low density parity check (LDPC) codes, the parity-check matrix can be extended to lower rates than conventional LTE turbo codes, which rely on repetition for code rates below <NUM>/<NUM>. This may allow the LDPC codes to achieve higher coding gains also at low coding rates, making them suitable for use cases requiring high reliability. As noted above, aspects of the present disclosure allow smaller may allow transport blocks to be segmented into slightly smaller CB sizes using lower coding rates to achieve higher coding gain.

In conventional systems (e.g., LTE), a transport block size (TB_size) table defines the TB size for certain combinations of modulation coding schemes (MCS) and number of resource blocks (Num_RB). Given a transport block size index (ITBS obtained from the MCS) and Num_RB, the transport block size (TB_size) can be obtained from the TB_size table as a number of bits.

In general, the number of over the air (OVA) bits needed for a TB transmission may be represented as a variable B, where: <MAT> to account for <NUM> cyclic redundancy check (CRC) bits. A TB with B larger than a maximum CB size is split (segmented) into multiple CBs. This segmentation process can be demonstrated by the following equations for a number of segmented code blocks (Num_CB) and approximate code block size (Appr_CB_size): <MAT> <MAT> In practice, code block sizes are quantized to K+ and K-, where K+ and K- are the two allowable CB sizes closest to Appr_CB_size. In current systems, CB segmentation is only a function of TB size. Thus, for multiple (MCS, Num_RB) combinations with the same TB size and Num_CB, the quantized CB sizes K+ and K- are all the same. Every CB may be encoded with a turbo code rate <NUM>/<NUM>, while the effective code rate is controlled by rate matching, repetition, or truncation. The Max_CB_size in such systems is <NUM> bits.

According to the claimed invention, however, a segmentation of transport blocks is dependent on code rate (as a criteria to select code block size). In other words, different code block sizes (values of K+ and K-) may be selected for segmentation based on a code rate. For example, a first code block size may be used for segmentation for a minimum code rate of <NUM>/<NUM> or more (e.g., LDPC using a first base graph BG1) while a second (smaller) code block size may be used for a minimum code rate less than <NUM>/<NUM> (e.g., LDPC using a second base graph BG2).

<FIG> illustrates example operations <NUM> for code rate dependent CB segmentation, according to the claimed invention. Operation <NUM> may be performed by any transmitting device (e.g., UE or base station). In some examples, operations <NUM> may be performed by elements of base station <NUM> or UE <NUM> as shown in <FIG>.

The operations begin, at <NUM>, by determining over the air resources available for sending a transport block (TB). At <NUM>, code block segmentation of the TB into multiple code blocks is performed, based on the determination of air link resources and a code rate. At <NUM>, the code blocks are transmitted. On the receive side, a device may perform corresponding operations as the transmitter, for example, determining the code rate-based code block size used for segmentation and processing the received code blocks accordingly.

For NR, various different segmentation parameters may be agreed upon, such as: <MAT>.

In addition to a max code block size, a code block threshold (CB_threshold) may also be introduced and used for segmentation. For example, for code block sizes below a threshold value (CB_size < CB_threshold), LDPC encoding rates may be lower than <NUM>/<NUM> (e.g., <NUM>/<NUM>). For code block sizes above the threshold value (CB_size > CB_threshold), LDPC encoding rate may be greater than or equal to <NUM>/<NUM>. The exact value of CB_threshold may be selected based on various factors, such as a desire to keep decoder length/complexity reasonable.

Code rate dependent segmentation described herein may be used as an alternative to lowering effective code rate by repetition.

This approach may be advantageous in cases where the gain from repetition may be less than the gain by reducing code rate. This may be illustrated by considering an example of a CB_size of <NUM> and a number of over the air bits (Num_OVA_bits) of <NUM>, where different code rates are considered for different schemes. According to a first scheme (Scheme <NUM>):.

In this example, a gain of <NUM>. 3dB may be obtained with Scheme2, which may be greater than the gain obtained by repetition in Scheme <NUM>. In this example, and following examples, <NUM>/<NUM> is used as an example of a threshold code rate, but other threshold code rates may be used to determine smaller code block sizes.

Aspects of the present disclosure may help enable transmission with a lower code rate, for example, by making (code block sizes of) TB segmentation resource dependent (e.g., considering code rate, and not just as a function of TB size).

As described herein, TB segmentation decisions may be made as a function of not only TB size, but also Num_OVA_bits (which depends on code rate). In general, Num_OVA_bits may be determined by modulation and coding scheme (MCS) and NUM_RB as follows:
(MCS, Num_RB) →Num_OVA_bits, where OVA is "over the air.

Unlike prior systems, the techniques presented herein may, thus, allow TBs with the same TB size but different resources to be segmented into different CB sizes, for example, so that the code rate of LDPC may be different. In general, the techniques may try to use OVA bits for lower code rate instead of repetition (to achieve better gain). This may apply only to code blocks of certain sizes B that are less than a maximum code block size, but greater than a threshold, such as: <MAT>.

A rule may be conceived that allows a different CB size between the maximum CB size and a threshold value to be used based on (effective) code rate. The effective code rate may be calculated as the number of bits to transmit (B) divided by the number of OVA bits used for transmission, and the rule may be expressed as:
If B/Num_OVA_bits > <NUM>/<NUM>,
Then: effective code rate ><NUM>/<NUM>, CB segmentation may be
based on a first CB size (e.g., using a first K+ and K- similar to LTE)
Else If B/Num_OVA_bits < <NUM>/<NUM>,
Then: CB segmentation may be performed and,
If the resulting CB_size < CB_threshold, it may already support a lower
code rate,
Then: the first CB size may be kept (e.g., LTE like CB
segmentation)
If resulting CB_size >= CB_threshold, and only support <NUM>/<NUM>
code rate,
Then: the CB segmentation may be redone using a
new/second CB size. For example, redoing the segmentation with a new CB size may be done as:
- Num_CB_new = B/(CB_threshold - <NUM>),
- Get new CB size K+ and K-
If CB_threshold<Max_CB_size, for a TB with B between CB_threshold
and Max_CB_size,
Then: the TB may be split it into more than one CBs (using the new
K+ and K-). The example above demonstrates code rate-based segmentation using a threshold code rate of <NUM>/<NUM>. In the example, a different segmentation of the TB is performed for code rates below <NUM>/<NUM>.

<FIG> illustrates an example of resource (code rate) dependent CB segmentation, for a first TB with a size B. As shown in the example of <FIG>, the CB threshold size may be less than the Max_CB_Size. Even though B is greater than the CB_threshold, but less than the Max_CB_Size, there may be no segmentation if the effective code rate is > <NUM>/<NUM>. On the other hand, if the effective code rate is < <NUM>/<NUM>, the TB may be split into two CBs (e.g., based on a new K+/K-).

For LDPC coding and assuming that the first TB has <NUM> bits (B = <NUM>), it could be transmitted as a single CB (of BG1) at a minimum code rate of <NUM>/<NUM> or it could be segmented into two CBs (of BG2) and transmitted with a minimum rate of <NUM>/<NUM>, to achieve coding gain such that different segmentation (using different code block sizes) of the same size TB may be performed based on code rate. To generalize this approach, the goal may be to segment if segmentation allows the use of a lower LDPC code rate rather than repeating more bits to reach the target code rate.

Referring again to <FIG>, for a second TB, with B > Max_CB_Size and a code rate threshold of <NUM>/<NUM>, a fixed segmentation may be used if the effective code rate > <NUM>/<NUM> or, rate-based segmentation may be used if the effective code rate is < <NUM>/<NUM>. As illustrated, the rate-based segmentation results in segmentation of the second TB into <NUM> slightly smaller code blocks.

Those skilled in the art will recognize that the values used in these examples are to facilitate understanding and various other suitable values may be used.

Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more.

For example, means for transmitting and/or means for receiving may comprise one or more of a transmit processor <NUM>, a TX MIMO processor <NUM>, a receive processor <NUM>, or antenna(s) <NUM> of the base station <NUM> and/or the transmit processor <NUM>, a TX MIMO processor <NUM>, a receive processor <NUM>, or antenna(s) <NUM> of the user equipment <NUM>. Additionally, means for generating, means for multiplexing, and/or means for applying may comprise one or more processors, such as the controller/processor <NUM> of the base station <NUM> and/or the controller/processor <NUM> of the user equipment <NUM>.

Claim 1:
A method for wireless communications, comprising:
determining (<NUM>) a number of resource blocks available for sending a transport block, TB;
performing (<NUM>) segmentation of the TB into smaller code blocks, CBs, based on the determined number of resource blocks and a code rate for the code blocks, wherein performing the segmentation comprises:
selecting a first code block size if the code rate is greater than or equal to a threshold code rate, else
selecting a second code block size if the code rate is less than the threshold code rate; and
transmitting (<NUM>) the CBs, wherein the code blocks are encoded using low density parity check, LDPC, coding.