Method and Apparatus for Non-Orthogonal Multiple Access Communication

Abstract

According to aspects of the disclosure, there is provided a method for a UE to select or be assigned or configured with a spreading sequence that is based on one or more communication parameters such as receiver type, receiver capability, SE, TBS, MCS, traffic load, PAPR requirement, MCL, number of layers, overloading, reliability requirement, transmission power consumption, number of active UEs, and transmission latency constraint, etc. In some embodiments, the spreading sequence may be related to a performance metric associated with an above parameter (PAPR, BLER, etc.). In some embodiments, this is achieved by associating spreading sequences with parameters or performance metrics, or both. In some instances the spreading sequences may be arranged or ordered in a manner to reduce signaling overhead (e.g., signaling an index is more efficient than signaling a value of a metric, and ordering correlates the index to the value).

What is claimed is: 
     
         1 . A method comprising:
 obtaining, by a transmitter, an indication of a group of spreading sequences, wherein each of the spreading sequences in the group are orthogonal to one another, wherein the group is one out of a plurality of N groups indexed from 0 to N−1 in a pool comprising N×M number of sequences, wherein N≥1 and M≥1, wherein each group comprising M number of sequences indexed from 0 to M−1, and wherein at least two spreading sequences in the pool are non-orthogonal to one another;   spreading, by the transmitter, a sequence of modulated symbols using one or more spreading sequences based on the indication to generate a sequence of spread symbols;   obtaining, by the transmitter, a set of resource-mapped symbols based on the sequence of spread symbols; and   transmitting, by the transmitter to a receiver, a non-orthogonal multiple access (NoMA) signal generated from the set of resource-mapped symbols.   
     
     
         2 . The method of claim i, wherein the spreading comprises:
 spreading, by the transmitter, a first sequence of modulated symbols using a first spreading sequence of the group of spreading sequences corresponding to the indication, to generate a first sequence of spread symbols; and   spreading, by the transmitter, a second sequence of modulated symbols using a second spreading sequence of the group of spreading sequences corresponding to the indication, to generate a second sequence of spread symbols.   
     
     
         3 . The method of  claim 2 , wherein the first spreading sequence and the second spreading sequence are at least one of:
 both associated with a same spreading factor;   associated with different spreading factors;   both associated with a same sparsity ratio; or   both associated with different sparsity ratios.   
     
     
         4 . The method of  claim 1 , wherein the spreading sequences in the group are ordered in a direction of increasing or decreasing value of a transmission metric associated with a respective spreading sequence. 
     
     
         5 . The method of  claim 4 , wherein the transmission metric is a performance metric that is at least one of:
 cubic metric (CM);   peak to average power ratio (PAPR);   reliability including block error rate (BLER);   transmission block size (TBS);   modulation and coding scheme (MCS);   overloading capability;   receiver capability;   allocated bandwidth;   maximum coupling loss (MCL) range; or   number of active user equipments (UEs).   
     
     
         6 . The method of  claim 1 , wherein the group of spreading sequences and respective spreading sequences in the group are each identified by a respective index value. 
     
     
         7 . The method of  claim 2 , further comprising:
 receiving, by the transmitter, a starting index for the first spreading sequence and at least one of:
 a direction of increasing index or decreasing index to identify the second spreading sequence, or 
 a hopping pattern of spreading sequence indices. 
   
     
     
         8 . The method of  claim 1 , wherein the indication further indicates at least one of:
 a type of spreading sequence to be used by the transmitter;   a number of spreading sequences per group;   a number of groups of spreading sequences;   a performance metric; or   a user equipment (UE) identifier (ID).   
     
     
         9 . The method of  claim 1 , wherein each spreading sequence in the pool is associated with a UE ID, and wherein the obtaining the indication comprises:
 selecting the group of spreading sequences based the UE ID.   
     
     
         10 . The method of  claim 1 , wherein the group of spreading sequences is grouped based on a type of spreading sequence, and wherein the type of spreading sequence is at least one of:
 a spreading sequence having only one non-zero element;   a spreading sequence having at least two non-zero elements and at least one zero element; or   a spreading sequence having no zero elements.   
     
     
         11 . The method of  claim 1 , further comprising:
 generating a pool of discrete Fourier transform (DFT) spreading sequences using a fast Fourier transform (FFT) algorithm, the pool including a plurality of groups and each group of the plurality of groups including at least one spreading sequence,   wherein the generating further comprises grouping spreading sequences based on at least one of:   characteristics of the spreading sequences in the plurality of groups; or   the spreading sequences in the plurality of groups being non-orthogonal with respect to at least one other spreading sequence in the pool, and each of the spreading sequences in the plurality of groups being orthogonal to one another.   
     
     
         12 . The method of  claim 1 , wherein the at least two spreading sequences are in two different groups. 
     
     
         13 . The method of  claim 1 , wherein the pool includes a second group of spreading sequences, and wherein the second group of spreading sequences includes at least one spreading sequence that is orthogonal to the each of the spreading sequences in the group. 
     
     
         14 . An apparatus comprising:
 at least one processor; and   a non-transitory computer readable storage medium storing programming for execution by the at least one processor, the programming including instructions to cause the apparatus to:   obtain an indication of a group of spreading sequences, wherein each of the spreading sequences in the group are orthogonal to one another, wherein the group is one out of a plurality of N groups indexed from 0 to N−1 in a pool comprising N×M number of sequences, wherein N≥1 and M≥1, wherein each group comprising M number of sequences indexed from 0 to M−1, and wherein at least two spreading sequences in the pool are non-orthogonal to one another;   spread a sequence of modulated symbols using one or more spreading sequences based on the indication to generate a sequence of spread symbols;   obtain a set of resource-mapped symbols based on the sequence of spread symbols; and   transmit a non-orthogonal multiple access (NoMA) signal generated from the set of resource-mapped symbols.   
     
     
         15 . The apparatus of  claim 14 , wherein the instructions to spread a sequence of modulated symbols comprise instructions to:
 spread a first sequence of modulated symbols using a first spreading sequence of the group of spreading sequences corresponding to the indication, to generate a first sequence of spread symbols; and   spread a second sequence of modulated symbols using a second spreading sequence of the group of spreading sequences corresponding to the indication, to generate a second sequence of spread symbols.   
     
     
         16 . The apparatus of  claim 15 , wherein the first spreading sequence and the second spreading sequence are at least one of:
 both associated with a same spreading factor;   associated with different spreading factors;   both associated with a same sparsity ratio; or   both associated with different sparsity ratios.   
     
     
         17 . The apparatus of  claim 16 , wherein the spreading sequences in the group are ordered in a direction of increasing or decreasing value of a transmission metric associated with a respective spreading sequence. 
     
     
         18 . The apparatus of  claim 17 , wherein the transmission metric is a performance metric that is at least one of:
 cubic metric (CM);   peak to average power ratio (PAPR);   reliability including block error rate (BLER);   transmission block size (TBS);   modulation and coding scheme (MCS);   overloading capability;   receiver capability;   allocated bandwidth;   maximum coupling loss (MCL) range; or   number of active user equipments (UEs).   
     
     
         19 . The apparatus of  claim 16 , wherein the group of spreading sequences is grouped based on a type of spreading sequence, wherein the type of spreading sequence is at least one of:
 a spreading sequence having only one non-zero element;   a spreading sequence having at least two non-zero elements and at least one zero element; or   a spreading sequence having no zero elements.   
     
     
         20 . The apparatus of  claim 14 , wherein the indication further indicates at least one of:
 a type of spreading sequence to be used by the apparatus;   a number of spreading sequences per group;   a number of groups of spreading sequences;   a performance metric; or   a user equipment (UE) identifier (ID).