Techniques for sparse code multiple access (SCMA) codebook design

The present disclosure describes a method, an apparatus, and a computer readable medium for a multilayer transmission in a wireless network. For example, the method may include generating a group of binary data bits for resources of each layer of a plurality of layers, mapping the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, combining the code words, and transmitting the combined code word to receiver in the wireless network. As such, the multilayer transmission in a wireless network is achieved.

BACKGROUND

The present disclosure relates generally to communication systems, and more particularly, to design of code books in sparse code multiple access (SCMA) networks.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

In wireless communications systems employing CDMA, data symbols are spread over orthogonal or near orthogonal code sequences in which a binary code is mapped to a quadrature amplitude modulation (QAM) symbol before a spreading sequence is applied. Although this type of encoding may provide relatively higher coding rates, it may not be enough to meet the demands of current wireless networks.

As such, new techniques or mechanisms to achieve even higher coding rates are needed to meet the growing demands of the wireless networks.

SUMMARY

According to one example, a method for multilayer transmission in a wireless network is provided. The method includes generating, at a transmitter, a group of binary data bits for resources of each layer of a plurality of layers; mapping, at the transmitter, the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers; combining, at the transmitter, the code words; and transmitting, from the transmitter, the combined code word to a receiver in the wireless network.

In another example, an apparatus for multilayer transmission in a wireless network is provided. The apparatus includes means for generating, at a transmitter, a group of binary data bits for resources of each layer of a plurality of layers; means for mapping, at the transmitter, the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers; means for combining, at the transmitter, the code words; and means for transmitting, from the transmitter, the combined code word to receiver in the wireless network.

In a further example, an apparatus for multilayer transmission in a wireless network is provided. The apparatus includes a memory; and at least one processor coupled to the memory and configured to generate, at a transmitter, a group of binary data bits for resources of each layer of a plurality of layers; map, at the transmitter, the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers; combine, at the transmitter, the code words; and transmit, from the transmitter, the combined code word to receiver in the wireless network.

Additionally, in another example, a computer readable medium storing computer executable code for a multilayer transmission is provided. The computer readable medium includes code to generate, at a transmitter, a group of binary data bits for resources of each layer of a plurality of layers; map, at the transmitter, the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers; combine, at the transmitter, the code words; and transmit, from the transmitter, the combined code word to receiver in the wireless network.

DETAILED DESCRIPTION

The present disclosure relates to a multilayer transmission at base station and/or a user equipment.

FIG.1is a diagram illustrating an example of a wireless communications system and an access network100including at least one base station102configured to include a multilayer transmission component420for multilayer transmission to at least one UE104in accordance with various aspects of the present disclosure. The wireless communications system100(also referred to as a wireless wide area network (WWAN)) includes base stations102, UEs104, and an Evolved Packet Core (EPC)160. The base stations102may include macro cells (high power cellular base station) and/or small cells (low power cellular base station). The macro cells include eNBs. The small cells include femtocells, picocells, and microcells.

The small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ LTE and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP150. The small cell102′, employing LTE in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. LTE in an unlicensed spectrum may be referred to as LTE-unlicensed (LTE-U), licensed assisted access (LAA), or MuLTEfire.

FIG.2Ais a diagram200illustrating an example of a DL frame structure in LTE, which may be an example of a frame structure that may be transmitted by at least one base station102configured to multilayer transmission component420for transmitting data in accordance with various aspects of the present disclosure.

FIG.2Bis a diagram230illustrating an example of channels within the DL frame structure in LTE that may be transmitted by base station102and used by UE104as described herein.

FIG.2Cis a diagram250illustrating an example of an UL frame structure in LTE that may be used by UE104.

FIG.2Dis a diagram280illustrating an example of channels within the UL frame structure in LTE that may be used by UE104. Other wireless communication technologies may have a different frame structure and/or different channels.

In LTE, a frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent the two time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into multiple resource elements (REs). In LTE, for a normal cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a total of 84 REs. For an extended cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme. Additionally, the RBs described above may also be referred to as “resources,” “orthogonal resources,” etc. in the present disclosure.

As illustrated inFIG.2A, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include cell-specific reference signals (CRS) (also sometimes called common RS), UE-specific reference signals (UE-RS), and channel state information reference signals (CSI-RS).FIG.2Aillustrates CRS for antenna ports 0, 1, 2, and 3 (indicated as R0, R1, R2, and R3, respectively), UE-RS for antenna port 5 (indicated as R5), and CSI-RS for antenna port 15 (indicated as R).

FIG.2Billustrates an example of various channels within a DL subframe of a frame. The physical control format indicator channel (PCFICH) is within symbol 0 of slot 0, and carries a control format indicator (CFI) that indicates whether the physical downlink control channel (PDCCH) occupies 1, 2, or 3 symbols (FIG.2Billustrates a PDCCH that occupies 3 symbols). The PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs (FIG.2Bshows two RB pairs, each subset including one RB pair). The physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0 and carries the HARQ indicator (HI) that indicates HARQ acknowledgement (ACK)/negative ACK (HACK) feedback based on the physical uplink shared channel (PUSCH). The primary synchronization channel (PSCH) is within symbol 6 of slot 0 within subframes 0 and 5 of a frame, and carries a primary synchronization signal (PSS) that is used by a UE to determine subframe timing and a physical layer identity. The secondary synchronization channel (SSCH) is within symbol 5 of slot 0 within subframes 0 and 5 of a frame, and carries a secondary synchronization signal (SSS) that is used by a UE to determine a physical layer cell identity group number. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DL-RS. The physical broadcast channel (PBCH) is within symbols 0, 1, 2, 3 of slot 1 of subframe 0 of a frame, and carries a master information block (MIB). The MIB provides a number of RBs in the DL system bandwidth, a PHICH configuration, and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

As illustrated inFIG.2C, some of the REs carry demodulation reference signals (DM-RS) for channel estimation at the eNB. The UE may additionally transmit sounding reference signals (SRS) in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by an eNB for channel quality estimation to enable frequency-dependent scheduling on the UL.FIG.2Dillustrates an example of various channels within an UL subframe of a frame. A physical random access channel (PRACH) may be within one or more subframes within a frame based on the PRACH configuration. The PRACH may include six consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. A physical uplink control channel (PUCCH) may be located on edges of the UL system bandwidth. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

The UL transmission is processed at the eNB310in a manner similar to that described in connection with the receiver function at the UE104. Each receiver318RX receives a signal through its respective antenna320. Each receiver318RX recovers information modulated onto an RF carrier and provides the information to a RX processor370.

Referring toFIG.4, in an aspect, a wireless communications system400(which may be the same as or similar to wireless communications system and an access network100ofFIG.1) includes a plurality of UEs (UEs402,404,406,408,410, and412, which may be the same or similar to UE104ofFIG.1) in communication coverage of at least one base station102. The base station102(collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with an EPC (such as EPC160ofFIG.1) through backhaul links132(e.g., S1 interface). In an aspect, base station102may include one or more processors (not shown) and, optionally, memory (not shown), that may operate in combination with multilayer transmission component420for transmitting data to the UEs. In an additional or optional aspect, any of the UEs (e.g., (UEs402,404,406,408,410, and/or412) may also include multilayer transmission component420, one or more processors (not shown), optionally, memory (not shown), that may operate in combination with multilayer transmission component420for transmitting data from the UE to the base station.

In an aspect, base station102which may include multilayer transmission component420may send a transmission (e.g., SCMA transmission)432on downlink120-a(only one downlink shown for simplicity) to one or more UEs (e.g.,402,404,406,408,410, and/or412). Although six UEs (referred to as users or layers in the present disclosure) are shown in theFIG.4, the present disclosure is not limited to six layers. In an example, four resources may be available at the base station for transmitting data to the six layers, e.g., users/UEs. At each layer, only two resources may be used for transmitting the data and no data is transmitted on the unused resources. At each layer, the data available for transmission on the downlink is converted to binary data bits. The binary data bits are then mapped to code words of a signal constellation (e.g., a code book of the respective layer) to maximize the distance between code words of a resource. The code words for all the layers are combined to generate a combined code word prior to transmission.

For example, base station102and/or multilayer transmission component420may be configured for multilayer transmission (e.g., transmission432) by generating a group of binary data bits for resources of each of the layers, mapping each of the groups of binary data bits to a respective code word in a signal constellation, wherein the mapping of each of the groups of binary data bits is based at least on maximizing a distance between the code words within each of the layers, combining the code words, and transmitting the combined code word. Additionally, the transmission432may be a sparse code multiple access transmission to achieve multi-dimensional coded modulation for non-orthogonal multiple access to meet the growing demands of wireless networks.

In an additional aspect, for example, one or more of the UEs (e.g., UE402,404,406,408,410, and/or412) may include multilayer transmission component420and may send a transmission (e.g., SCMA transmission) on uplink120-b(only one uplink shown for simplicity reasons) to the base station. As the uplinks are synchronized, the transmissions from the one or more UEs are combined at a receiving antenna of the base station. Further, the base station decodes the data transmitted on each layer using a code book associated with the respective layer to determine the data transmitted on each layer. Furthermore, a UE may be assigned more than one layer by the base station.

In a further additional aspect, multilayer transmission component420may include a binary data generating component422, a mapping component424, a combining component426, and/or a transmitting component428for performing the multilayer transmission. Further, multilayer transmission component420and other components (422,424,426, and/or428) may reside at base station102for multilayer transmission from the base station to the one or more UEs and/or at UE104for multilayer transmission from the one or more UEs to the base station.

FIG.5is a diagram illustrating a non-limiting example of a multilayer transmission500in a wireless communications system such as system100(FIG.1) or system400(FIG.4).

For example, in an aspect, a non-limiting example with six layers, four resources is described. Each layer uses two resources out of the four available resources, as described below in reference toFIG.6. That is, each layer uses two resources (out of the four available resources) for transmission and no data is transmitted on the other two non-used resources. The resources used by a layer may be referred to as non-zero resources and the resources not used by the layer may be referred to as zero resources. Further, in an aspect, the resources may be orthogonal to each other (e.g., orthogonal resources) and may be RBs as described above in reference toFIG.2A. Additionally, a 1stresource and a 2ndresource inFIG.5represent the used (e.g., non-zero) resources at a layer and may include any two of the four resources (e.g., any two of resources R1, R2, R3, and/or R4, as described below in reference toFIG.6).

At each layer, an FEC encoder (e.g., FEC encoders531,532,533,534,535, and/or536) converts the data available for transmission at each layer to binary data bits. For instance, data available for transmission at layer C1 may be converted to binary data bits, 0 or 1, for each of the resources, e.g., for 1stresource and the 2ndresource. For example, in an aspect, FEC encoder531may output binary data bits (0,0) at layer C1 for the two resources used by layer C1. The two bits are for the two resources used at layer C1 (e.g., two non-zero resources at layer C1). In an additional or optional aspect, FEC encoder531may output binary data bits (0,1), (1,0), or (1, 1) at layer C1 based on the data available for transmission at the first and second resources of layer C1. A similar procedure may be used at layers C2-C6 for converting the data available for transmission at layers C2-C6 into binary data bits. For example, in an additional or optional aspect, FEC encoder536may output binary data bits (0,0), (0,1), (1,0), and/or (1,1) at layer C6 corresponding to the two resources used by layer C6. Although, the above example is described in the context of two bits, the disclosure is not limited to two bits for each layer. For instance, four bits may be used for each layer, e.g., (0,0,0,0), (0,0,0,1), (0,0,1,0), etc.

In an aspect, the output of an FEC encoder is mapped to code words. For instance, in an aspect, output of FEC encoder531(e.g., (0,0)) may be mapped to 3 and −1. The mapping of the binary data bits to code words in a signal constellation (also referred to as a “code book”) is based at least on maximizing distance between the code words of different layers, specifically the code words that are close. For example, as described below in reference toFIG.7, binary data bits (0,0) associated with layer C1 are mapped to (3, −1), binary data bits (0,1) associated with layer C1 are mapped to (1, 3), binary data bits (1,0) associated with layer C1 are mapped to (−1, −3), and binary data bits (1,1) associated with layer C1 are mapped to (−3, 1). For instance, the binary data bits (0,0) and (0,1) are separated by the maximum distance possible in the signal constellation by mapping them to (3, −1) and (1,3). This allows the receiver (e.g., receiver at UE104or base station102) to correctly detect the pair of transmitted bits.

Additionally, each of the layers C2-C6 may have its own code book such that the mapping of the binary bits of a layer maximizes distance between the code words between the layers. Although, the mapping of resources (e.g., used/non-zero resources) at layer C1 is described above, similar mapping procedures may be designed or implemented for resources at layers C2-C6. For example, binary data bits of layers 2-6 associated with the first and second resources may be mapped as shown below:

Further, in an aspect, the code words for each of the layers may be combined, e.g., to a combined code word, prior to transmission. For instance, in an aspect, the code words associated with all the layers of a resource are combined via a linear combiner570to produce a combined code word for that resource. For example, code words for resource “R1,” e.g., code words 3, c21, and c31 may be combined to produce a combined code word “A” to be transmitted on resource R1. Additionally, code words for resource “R2,” e.g., code words −1, c42, and c52 may be combined to produce a combined code word “B” to be transmitted on resource R2. As a result, on the receiving side (e.g., at UE104or base station102), the received signal will be a linear combination of all the layers on a particular resource. As such, when the receiver receives the multilayer transmission432, the receiver searches for combinations of all possible signals for decoding at the receiver. As described above, data for multiple layers are transmitted from the base station. In additional aspect, the layers may be assigned to one UE, two UEs, three UEs, and so on. For instance, all the layers (i.e., six layers) may be assigned to UE104for increasing throughput at the UE.

Additionally, the signal constellation/code book mechanism/procedure described above is from a base station perspective, and a same/similar mechanism/procedure may be defined/implemented at a UE for transmission on an uplink at the base station.

FIG.6is a diagram illustrating a non-limiting example of resource allocation600among various layers in a wireless communications system such as system100(FIG.1) or system400(FIG.4).

For example, in an aspect, the number of resources may be defined as “M” and the number of layers may be defined as “N,” wherein the value of M is less than N. That is, the number of resources is less than the number of layers (e.g., UEs). This may result in the resources being shared by the layers (e.g., non-dedicated resources). The data may be transmitted on a downlink from base station102to one or more UEs104or on the uplink from one or more UEs104to base station102. AlthoughFIG.6is described in the context of four resources and six layers, the procedure/mechanism may be applied to any other numbers of resources and/or layers.

In an aspect, the resources may be represented by rows—R1 (610), R2 (620), R3 (630), and R4 (640) and the layers may be represented by columns—C1 (615), C2 (625), C3 (635), C4 (645), C5 (655), and C6 (655). Each of the resources may comprise one or more RBs which are described above in detail in reference toFIG.2A. Additionally, as described above in reference toFIGS.4-5, each of the layers may use two resources (out of a total of the four available resources) for transmission. That is, data is transmitted on only two resources (out of the four resources) for each layer and no data is transmitted on the other two resources. In an example aspect, the resources used by a layer may be referred to as “used” or “non-zero” resources and the resources not used by the layer may be referred to as “unused” or “zero” resources.

In an aspect, the four resources may be allocated or assigned among the six layers with each of the layers using two resources for transmission as illustrated inFIG.6. For example, layer C1 (615) may use resources R1 (610) and R2 (620), layer C2 (625) may use resources R1 (610) and R3 (630), layer C3 (635) may use resources R1 (610) and R4 (640), layer C4 (645) may use resources R2 (620) and R3 (630), layer C5 (655) may use resources R2 (620) and R4 (640), and layer C6 (665) may use resources R3 (630) and R4 (640).

Additionally, for each of the layers, no transmission occurs on each of the other two resources not used by a layer. For example, no transmission occurs on resources R3 (630) and R4 (640) for layer C1 (615), no transmission occurs for resources R2 and R4 for layer C2, no transmission occurs for resources R2 and R3 for layer C3, no transmission occurs for resources R1 and R4 for layer C4, no transmission occurs for resources R1 and R3 for layer C5, and no transmission occurs for resources R1 and R1 for layer C6.

In an additional aspect, a pair of layers may be configured as an orthogonal pair. For example, layers C1 (615) and C6 (665) may be configured as an orthogonal pair, layers C2 (625) and C5 (655) may be configured as another orthogonal pair, and/or layers C3 (635) and C4 (645) may be configured as an additional orthogonal pair. That is, the six layers are configured as three orthogonal pairs. In an aspect, a pair of layers may be configured as an orthogonal pair if they use different resources for transmission. For instance, layer C1 (615) uses resources R1 (610) and R2 (620) for transmission and layer C6 (665) uses resources R3 (630) and R4 (640) for transmission. As the resources used by layers C1 and C6 are different resources, layers C1 and C6 may be configured or defined as an orthogonal pair. Further, layer C2 uses resources R1 and R3 for transmission and layer C5 uses resources R3 and R4 for transmission. As the resources used by layers C2 and C5 are different, layers C2 and C5 are defined as an orthogonal pair. Furthermore, layer C3 uses resources R1 and R4 for transmission and layer C4 uses resources R2 and R3 for transmission. As the resources used by layers C3 and C4 are different resources (in other words, different orthogonal resources), layers C1 and C6 are defined as an orthogonal pair

In an additional aspect, layers may be rotated to increase distance between code words of each of the layers. For example, in an aspect, layer C2 (625) may be rotated by 60° from layer C1 (615) to increase the distance between the code words, for example, in two dimension, from layer C1. Further, layer C3 (635) may be rotated by 120° from layer C1 to increase the distance, for example, in two dimension, from layer C1. That is, layer C3 is rotated an additional 60° from layer C2 to increase the distance from C2. This may increase the success rate of decoding at the receiver when the receiver is decoding the data received at the receiver as the code words are separated. In an additional or optional aspect, layer C2 (625) may be rotated by 45° from layer C1 (615) to increase the distance between the code words, for example, in two dimension, from layer C1. Further, layer C3 (635) may be rotated by 90° from layer C1 to increase the distance, for example, in two dimension, from layer C1. That is, layer C3 is rotated an additional 45° from layer C2 to increase the distance from C2. As the layers are rotated differently, the performance at the receiving end may differ as well. For instance, the performance achieved with rotating the layers 60°/120° is better than the performance achieved by rotating the layers 45°/90° as illustrated inFIGS.9A,9B,10,11B, and11C.

FIG.7is a diagram illustrating a non-limiting example of mapping binary data bits of a group of layers to code words in a wireless communications system such as system100(FIG.1) or system400(FIG.4).

For example, in an aspect, binary data bits associated with each of the resources of the layers are mapped to code words in a signal constellation (e.g., a codebook), wherein each of the layers may have its own codebook. For instance, in reference to layer C1, binary data bits “0” and “0” (represented by (0,0) inFIG.7) associated with resources R1 and R2 may be mapped to “3” and “−1,” respectively. Additionally, in reference to layer C1, binary data bits (0,1) associated with resources R1 and R2 may be mapped to “1” and “3,” respectively; binary data bits (1,0) associated with resources R1 and R2 may be mapped to “−1” and “−3,” respectively; and binary data bits (1,1) associated with resources R1 and R2 may be mapped to “−3” and “1,” respectively. For instance, in an aspect, the mapping of resources, e.g., R1 and R2 of layer C1, to code words 3 and −1, is performed in such as way the distance between the code words (of the signal constellation or code book) is maximized to increase the likelihood of successful decoding at the receiver. Although, the mapping of the binary data bits to code words in a signal constellation is described above in the context of one layer, e.g., layer C1, similar mapping procedure may be implemented for each of the other layers.

FIG.8is a diagram illustrating a non-limiting example of mapping of a group of binary data bits to code words in a wireless communications system such as system100(FIG.1) or system400(FIG.4). For example, the mapping of a group of binary data bits associated with layer C1 to code words in a signal constellation (e.g., a codebook) of layer C1 are shown inFIG.8.

FIGS.9A-Billustrate non-limiting examples of code book designs900and950in a wireless communications system such as system100(FIG.1) or system400(FIG.4). For example,FIG.9Aillustrates a code book design for layer C1 with the signal constellation rotated by 60° for layer C2 and 120° for layer C3 (referred to as “Design 1”). Additionally,FIG.9Billustrates an additional code book design for layer C1 with the signal constellation rotated by 45° for layer C2 and 90° for layer C3 (referred to as “Design 2”).

FIG.10is a diagram illustrating code book performance with six layers, 4 resources (or symbols) per layers, and 2 bits used per each layer. As illustrated inFIG.10, the performance of Design 1 (i.e., rotated by 60°/120°) is relatively better than the performance of Design 2 (i.e., rotated by 45°/90°), both of which are relatively better than know code book designs.

FIGS.11A-Cillustrate code book performance with known code book designs (FIG.11A) and Design 1 (i.e., rotated by 60°/120°) and Design 2 (i.e., rotated by 45°/90°).

FIGS.12A-Billustrate code book performance with a known code book design, and Design 1 (i.e., rotated by 60°/120°) and Design 2 (i.e., rotated by 45°/90°) in accordance with aspects of the present disclosure.

FIG.13is a flow diagram of an aspect of a multilayer transmission, which may be executed by the multilayer transmission component420ofFIG.4. Referring toFIG.13, a base station such as base station102and/or UE104(FIGS.1and4) may include one or more processors to perform an aspect of a method1300for a multilayer transmission. While, for purposes of simplicity of explanation, the method is shown and described as a series of acts, it is to be understood and appreciated that the method is not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, it is to be appreciated that a method could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a method in accordance with one or more features described herein.

In an aspect, at block1310, the method1300may include generating, at a transmitter, a group of binary data bits for resources of each layer of a plurality of layers. For example, in an aspect, base station102and/or multilayer transmission component420may generate a group of binary data bits (for example, (0,0) for layer C1, etc.) for resources of all six layers. In an aspect, binary data generating component422may generate the group of binary data bits for resources of each layer of the plurality of layers. In an additional or optional aspect, generating a group of binary data bits may be performed by/at a FEC encoder (e.g., FEC encoder531for layer C1). In an additional or optional aspect, UE104and/or multilayer transmission component420may generate a group of binary data bits (for example, (0,0) for layer C1, etc.) for resources of all six layers.

In an aspect, at block1320, the method1300may include the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers. For example, in an aspect, base station102and/or multilayer transmission component420may map each of the groups of binary data bits (for example, (0,0)) to respective code words (for example, (3, −1)) in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers (e.g., distance is maximized between 3 and −1). In an aspect, mapping component424may perform the mapping. In an additional or optional aspect, mapping may be performed by at/by a code book (e.g., code book551for layer C1). In an additional or optional aspect, UE104and/or multilayer transmission component420may map the group of binary data bits of each layer of the plurality of layers to respective code words in a signal constellation, wherein the mapping is based at least on maximizing a distance between the code words within each layer of the plurality of layers.

In an aspect, at block1330, the method1300may include combining, at the transmitter, the code words. For example, in an aspect, base station102and/or multilayer transmission component420may combine the code words at the transmitter, e.g., prior to transmission. In an aspect, combining component426may perform the combining. In an additional or optional aspect, the combining may be performed at/by a linear combiner570. In an additional or optional aspect, UE104and/or multilayer transmission component420may combine, at the transmitter, the code words.

In an aspect, at block1340, the method1300may include transmitting, from the transmitter, the combined code word to a receiver in the wireless network. For example, in an aspect, in an aspect, base station102and/or multilayer transmission component420may transmit the combined432. In an aspect, transmitting component428may perform the transmission. In an additional or optional aspect, UE104and/or multilayer transmission component420may transmit the combined code word to a receiver in the wireless network.

In an example aspect, base station102may be the transmitter and UE104may be the receiver, for example, in a downlink SCMA transmission from base station102to UE104. In an additional example aspect, UE104may be the transmitter and base station102may be the receiver, for example, in an uplink SCMA transmission from UE104to base station102.

FIG.14is a conceptual data flow diagram1400illustrating the data flow between different means/components in an exemplary apparatus1402that includes multilayer transmission component1420, which may be the same as or similar to multilayer transmission component420ofFIG.4for multilayer transmission. The apparatus may be a base station, which may be base station102ofFIG.1or4, and/or a UE which may be UE104ofFIG.1or4. The apparatus includes a binary data generating component1406to generate a group of binary data bits for resources of each of the layers, a mapping component1408to map each of the groups of binary data bits to a respective code word in a signal constellation, a combining component1410to combine the code words, and a transmission component1412to transmit the combined code word, and a reception component1404that receives one or more signals (e.g., combined code words) from UE1450.

FIG.15is a diagram1500illustrating an example of a hardware implementation for an apparatus1502′ employing a processing system1514that includes multilayer transmission component1420(ofFIG.14), which may be the same as or similar to multilayer transmission component420(ofFIG.4) for multilayer transmission. The processing system1514may be implemented with a bus architecture, represented generally by bus1524. The bus1524may include any number of interconnecting buses and bridges depending on the specific application of the processing system1514and the overall design constraints. The bus1524links together various circuits including one or more processors and/or hardware components, represented by the processor1504, components1404,1406,1408,1410, and1412, and computer-readable medium/memory1506. The bus1524may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1514may be coupled to a transceiver1510. The transceiver1510is coupled to one or more antennas1520. The transceiver1510provides a means for communicating with various other apparatus over a transmission medium. The transceiver1510receives a signal from the one or more antennas1520, extracts information from the received signal, and provides the extracted information to the processing system1514, specifically the reception component1404. In addition, the transceiver1510receives information from the processing system1514, specifically the transmission component1412, and based on the received information, generates a signal to be applied to the one or more antennas1520. The processing system1514includes a processor1504coupled to a computer-readable medium/memory1506. The processor1504is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1506. The software, when executed by the processor1504, causes the processing system1514to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1506may also be used for storing data that is manipulated by the processor1504when executing software. The processing system1514further includes at least one of the components1404,1406,1408,1410, and1412. The components may be software components running in the processor1504, resident/stored in the computer readable medium/memory1506, one or more hardware components coupled to the processor1504, or some combination thereof.

In one configuration, the apparatus1502/1502′ for wireless communication includes means for generating a group of binary data bits for resources of each of the layers; means for mapping each of the groups of binary data bits to a respective code word in a signal constellation, wherein the mapping of each of the groups of binary data bits is based at least on maximizing a distance between the code words within each of the layers; means for combining the code words; and means for transmitting the combined code word. The aforementioned means may be one or more of the aforementioned components of the apparatus1502and/or the processing system1514of the apparatus1502′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1514may include the TX Processor316, the RX Processor370, and the controller/processor375. As such, in one configuration, the aforementioned means may be the TX Processor316, the RX Processor370, and the controller/processor375configured to perform the functions recited by the aforementioned means. In an additional aspect, the processing system1514may include the TX Processor368, the RX Processor356, and the controller/processor359. As such, in another configuration, the aforementioned means may be the TX Processor368, the RX Processor356, and the controller/processor359configured to perform the functions recited by the aforementioned means.