Systems and Methods for Sparse Code Multiple Access

• US 20140140360A1
• Filed: 12/28/2012
• Published: 05/22/2014
• Est. Priority Date: 11/16/2012
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Nikopour, Hosein, Baligh, Mohammadhadi
• Granted Patent: US 9,240,853 B2
• Time in Patent Office: Days
• US Class Current: 370/479
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0473 taking constraints in layer or codeword to antenna mapping into account
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/0074 Code shifting or hopping
• CPC Class Codes: H04L 27/345 Modifications of the signal space to allow the transmission of additional information
• CPC Class Codes: H04L 27/362 Modulation using more than one carrier, e.g. with quadrature carriers, separately amplitude modulated H04L27/366 takes precedence
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA

Abstract

Coding gains can be achieved by encoding binary data directly to multi-dimensional codewords, which circumvents QAM symbol mapping employed by conventional CDMA encoding techniques. Further, multiple access can be achieved by assigning different codebooks to different multiplexed layers. Moreover, sparse codewords can be used to reduce baseband processing complexity on the receiver-side of the network, as sparse codewords can be detected within multiplexed codewords in accordance with message passing algorithms (MPAs).

Claims

1. A method for multiplexing data, the method comprising:

receiving a first binary or M-ary data associated with a first multiplexed layer;

encoding the first binary or M-ary data by selecting a first codeword from a first codebook, wherein the first codebook is assigned exclusively to the first multiplexed layer;

multiplexing the first codeword with at least a second codeword from a second codebook to obtain multiplexed codewords, wherein the second codebook is assigned exclusively to a second multiplexed layer; and

transmitting the multiplexed codewords over shared resources of a network.

2. The method of claim 1, wherein encoding the first binary or M-ary data by selecting the first codeword comprises:

selecting the first codeword from a first set of codewords in the first codebook in accordance with a binary or M-ary value of the first binary or M-ary data, wherein each codeword in the first set of codewords is associated with a different binary or M-ary value.

3. The method of claim 2, wherein each codeword in the first set of codewords comprises a low density of non-zero values such that the corresponding codeword can be detected within multiplexed codewords in accordance with a message passing algorithm (MPA).

4. The method of claim 1, wherein the first multiplexed layer is associated with a first user and the second multiplexed layer is associated with a second user.

5. The method of claim 1, wherein the first multiplexed layer and the second multiplexed layer carry separate data streams associated with a common.

6. The method of claim 5, wherein the first multiplexed layer and the second multiplexed layer occupy different multiple-input-multiple-output (MIMO) spatial layers.

7. The method of claim 5, wherein the first multiplexed layer and the second multiplexed layer occupy different Orthogonal Frequency-Division Multiple Access (OFDMA) tones.

8. A transmitter comprising:

a processor; and

a computer readable storage medium storing programming for execution by the processor, the programming including instructions to;

receive a first binary or M-ary data associated with a first multiplexed layer;

encode the first binary or M-ary data by selecting a first codeword from a first codebook, wherein the first codebook is assigned exclusively to the first multiplexed layer;

multiplex the first codeword with at least a second codeword from a second codebook to obtain multiplexed codewords, wherein the second codebook is assigned exclusively to a second multiplexed layer; and

transmit the multiplexed codewords over shared resources of a network.

9. A method for receiving data, the method comprising:

receiving a signal carrying multiplexed codewords, the multiplexed codewords including a plurality of codewords communicated over shared resources of a network, wherein each of the plurality of codewords belongs to a different one of a plurality of codebooks, wherein each of the plurality of codebooks are associated with a different one of a plurality of multiplexed layers;

identifying, by a receiver, a first one of the plurality of codewords within the multiplexed codewords, the first codeword belonging to a first one of the plurality of codebooks assigned exclusively to a first one of the plurality of multiplexed layers, wherein the receiver is associated with the first multiplexed layer; and

decoding the first codeword to obtain a first binary or M-ary data.

10. The method of claim 9, wherein identifying the first codeword within the multiplexed codewords comprises applying a message passing algorithm (MPA) to detect the first codeword amongst the plurality of codewords included within the multiplexed codewords.

11. The method of claim 10, wherein decoding the first codeword to obtain the first binary or M-ary data comprises:

mapping the first codeword directly to a binary or M-ary value of the first binary or M-ary data, wherein each codeword in the first codebook is associated with a different binary or M-ary value.

12. The method of claim 10, wherein different ones of the plurality of multiplexed layers occupy different multiple-input-multiple-output (MIMO) spatial layers.

13. The method of claim 9, wherein different ones of the plurality of multiplexed layers occupy different Orthogonal Frequency-Division Multiple Access (OFDMA) tones.

14. A receiver comprising:

a processor; and

a computer readable storage medium storing programming for execution by the processor, the programming including instructions to;

receive a signal carrying multiplexed codewords, the multiplexed codewords including a plurality of codewords communicated over shared resources of a network, wherein each of the plurality of codewords belongs to a different one of a plurality of codebooks, wherein each of the plurality of codebooks are associated with a different one of a plurality of multiplexed layers;

identify a first one of the plurality of codewords within the multiplexed codewords, the first codeword belonging to a first one of the plurality of codebooks assigned exclusively to a first one of the plurality of multiplexed layers, wherein the receiver is associated with the first multiplexed layer; and

decode the first codeword to obtain a first binary or M-ary data.

15. A method for designing Sparse Code Multiple Access (SCMA) code, the method comprising:

generating a plurality of multi-dimensional modulation codebooks; and

generating a plurality of sparse codebooks from the plurality of multi-dimensional modulation codebooks.

16. The method of claim 15, wherein each of the plurality of sparse codebooks comprises a plurality of sparse codewords, and wherein different sparse codewords within a sparse codebook are associated with different binary values.

17. The method of claim 15, wherein each codeword in the plurality of sparse codebooks comprise a low density of non-zero values such that the corresponding codeword can be detected within multiplexed codewords in accordance with a message passing algorithm (MPA).

18. The method of claim 15, wherein each of plurality of multi-dimensional modulation codebooks are assigned to a different multiplexed layer.

19. A method for designing Sparse Code Multiple Access (SCMA) code, the method comprising:

generating a plurality of mapping matrices;

generating at least one multi-dimensional constellation;

optimizing one or more of a permutation, a phase operator, and a conjugate operator; and

generating SCMA codewords in accordance with the mapping matrices, the at least one multi-dimensional constellation, and one or more of the permutation, the phase operator, and the conjugate operator.

20. A method for designing low density signature (LDS) code, the method comprising:

generating a plurality of mapping matrices;

optimizing one or more phase operators; and

generating LDS signatures in accordance with the mapping matrices, the one or more phase operators, and a constellation.

21. The method of claim 20, wherein each of the LDS signatures are assigned to a different multiplexed layer.