Systems and methods for spreading and co-orthogonal multi-stream spreading
Systems and methods are provided for spreading symbols over multiple time-frequency resources that rely on simple base constellations that can be sent over a frequency tone or time slot. A set of input bits (or an input symbol) are mapped to K symbols, and a symbol-to-resource-element mapping is applied that maps the K symbols to resource units. The mapping to the K symbols may be a linear mapping that maps an input symbol to K target tones through a 2K×2 real matrix, where input symbol is a complex point in a base constellation, and is considered as a 2-dimensional real vector. Up to K co-orthogonal 2K×2 real matrices (whose columns are orthogonal to each other) can be associated with the subset of K target tones. Each of the K co-orthogonal matrices can be used for mapping of an independent symbol from a separate steam of symbols which can be associated to a single UE or separate UEs.
1. A method of transmitting comprising:
using an input symbol mapping, mapping a first input symbol to K symbols, the first input symbol being a point on a 2B-ary constellation, each of the K symbols belonging to a respective one-dimensional constellation consisting of M points, where K>=2 and 2B>=M;
applying a symbol-to-resource-element mapping to the K symbols; and
transmitting on resources according to the symbol-to-resource-element mapping.
2. The method of claim 1 , wherein the symbol-to-resource-element mapping maps the K symbols to K tones out of T OFDM tones.
3. The method of claim 1 ,
wherein the input symbol mapping comprises a first mapping that maps a real component of the first input symbol to K real components and K imaginary components of the K symbols, and a second mapping that maps an imaginary component of the first input symbol to the K real components and the K imaginary components of the K symbols.
4. The method of claim 1 , further comprising:
modulating a first input bit stream to produce the first input symbol.
5. The method of claim 4 , wherein the modulation is performed using QAM modulator with Gray labeling.
6. The method of claim 4 , wherein the modulation is performed using QAM modulator with non-Gray labeling.
7. The method of claim 1 , further comprising repeating the using the input symbol mapping and the applying the symbol-to-resource-element mapping for another independent input symbol using a different linear mapping.
8. The method of claim 1 , wherein the using the input symbol mapping and the applying the symbol-to-resource-element mapping are performed by a first transmitter, the method further comprising:
in each of a plurality of other transmitters, also performing input symbol mapping and symbol-to-resource-element mapping but using a respective mapping of a corresponding plurality of mappings in place of the input symbol mapping.
9. The method of claim 1 , wherein applying the symbol-to-resource-element mapping and transmitting comprises transmitting the K symbols using K resources out of T resources, where 2<=K<=T, and the K resources being defined by a first signature of length T.
10. The method of claim 9 , further comprising:
prior to transmitting the K symbols using the K resources out of the T resources, multiplying the K symbols by a scrambling sequence, or an interleaving matrix, or a scrambling sequence and an interleaving matrix.
11. A method of transmitting comprising:
for each of L input symbols, mapping the input symbol to a respective set of K symbols using a respective one of L input symbol mappings, wherein the input symbol is a point on a 2B-ary complex plane, and each symbol of the respective set of K symbols belonging to a respective one-dimensional constellation consisting of M points, wherein both L and K are positive integer numbers, 2B>=M, and K>=2;
performing symbol-wise combining of the L sets of K symbols to produce a combined set of K symbols; and
applying a symbol-to-resource-element mapping to the combined set of K symbols, and transmitting an output of the symbol-to-resource-element mapping.
12. The method of claim 11 , wherein each input symbol mapping comprises a first mapping that maps a real component of the input symbol to K real components and K imaginary components of the respective set of K symbols, and a second mapping that maps an imaginary component of the input symbol to the K real components and the K imaginary components of the respective set of K symbols.
13. The method of claim 12 , wherein the L mappings are co-orthogonal mappings.
14. The method of claim 12 , further comprising:
modulating at least one input bit stream to produce the L input symbols.
15. The method of claim 14 , wherein K<T, T being a positive integer number.
16. The method of claim 15 , wherein M=2B, and wherein there is a one-to-one mapping between the input symbol and one of the M points.
17. The method of claim 15 , wherein 2B>M, and wherein multiple inputs are mapped to a same point from the M points.
18. The method of claim 17 , wherein an initial mapping is used for one of the respective sets of K symbols, and a mapping derived from the initial mapping is used for each of the other respective sets of K symbols.
19. The method of claim 18 , wherein the initial mapping uses an initial labelling of a constellation point, and for consecutive mappings comprising a previous mapping and a subsequent mapping, for the subsequent mapping a permutation maps an l i+1 -th labeling to the constellation point which was associated with an l i th label in the previous mapping, where l i+1 mod 2B, where r is a primitive root of 2B.
20. The method of claim 11 , further comprising:
repeating the mapping for another set of input symbols using a different signature; and
combining outputs produced using different signatures prior to transmission.
21. The method of claim 11 , wherein applying a symbol-to-resource-element mapping and transmitting comprises transmitting the combined set of K symbols using K resources out of T resources, where 2<=K<=T, and the K resources being defined by a first signature, and transmitting zeros on the remaining of the T resources.
22. The method of claim 21 , further comprising:
in a different transmitter, performing the input symbol mapping, the symbol-to-resource-element mapping, combining and transmitting using further mappings for a further set of L input symbols or a different number of input symbols.
23. The method of claim 21 , wherein the K resources out of T possible resources comprise K tones out of T OFDM tones.
24. A device comprising:
a non-transitory memory storage comprising instructions; and
a processor in communication with the non-transitory memory storage, wherein the processor execute the instructions to:
use an input symbol mapping to map a first input symbol to K symbols, the first input symbol being a point on a 2B-ary constellation, each of the K symbols belonging to a respective one-dimensional constellation consisting of M points, where K>=2 and 2B>=M;
apply a symbol-to-resource-element mapping to the K symbols; and
transmit an output of the symbol-to-resource-element mapping on resources.
25. The device of claim 24 , wherein the instructions to transmit the output of the symbol-to-resource-element mapping on the resources comprise instructions to transmit the K symbols using K resources out of T resources, wherein 2<=K<=T, the K resources being defined by a first signature of length T.
26. The device of claim 24 , wherein
the input symbol mapping comprises a first mapping that maps a real component of the first input symbol to K real components and K imaginary components of the K symbols, and a second mapping that maps an imaginary component of the first input symbol to the K real components and the K imaginary components of the K symbols.