Method and apparatus for data transmission using multiple transmit antennas
A method and apparatus for increasing the data rate and providing antenna diversity using multiple transmit antennas is disclosed. A set of bits of a digital signal are used to generate a codeword. Codewords are provided according to a channel code. Delay elements may be provided in antenna output channels, or with suitable code construction delay may be omitted. n signals represent n symbols of a codeword are transmitted with n different transmit antennas. At the receiver MSLE or other decoding is used to decode the noisy received sequence. The parallel transmission and channel coding enables an increase the data rate over previous techniques, and recovery even under fading conditions. The channel coding may be concatenated with error correction codes under appropriate conditions.
1. An encoder, comprising:
a processor configured to:
employ a trellis structure with branches such that the branches of the trellis structure have labels that correspond to sets comprising of n symbols that are elements of a signal constellation;
select a branch of the trellis structure based on input data, and a previous state of the encoder; and
transmit a set of the sets of n symbols of the signal constellation that corresponds to a branch label of the branch that is selected, over a plurality of n antennas simultaneously.
2. The encoder of claim 1 , wherein the branch is selected by selecting, at each time t, branches of a form q t 1 q t 2 . . . q t n .
3. The encoder of claim 1 , wherein the encoder transmits using phase shifts of a carrier.
4. The encoder of claim 1 , wherein the encoder delays a transmission of at least one symbol by a predetermined time delay.
5. The encoder of claim 1 , wherein the trellis structure comprises a space-time code.
6. The encoder of claim 1 , wherein the encoder converts each of the n symbols into baseband signals and multiplies each of the baseband signals by a selected, respective, PN bit sequence.
7. The encoder of claim 6 , wherein a first of the respective PN bit sequence is the same as a second of the respective PN bit sequence.
8. The encoder of claim 6 , wherein a first of the respective PN bit sequence is correlated to a second of the respective PN bit sequence.
9. A method of encoding, comprising:
employing a trellis structure with branches such that the branches of the trellis structure have labels that correspond to sets comprising of n symbols that are elements of a signal constellation;
selecting, by a processor, a branch of the trellis structure based on input data, and a previous state of an encoder; and
transmitting a set of the sets of n symbols of the signal constellation that corresponds to a branch label of the branch that is selected, over a plurality of n antennas simultaneously.
10. The method of claim 9 , wherein the branch is selected by selecting, at each time t, branches of a form q t 1 q t 2 . . . q t n .
11. The method of claim 9 , wherein the transmitting uses phase shifts of a carrier.
12. The method of claim 9 , wherein the transmitting delays a transmission of at least one symbol by a predetermined time delay.
13. The method of claim 9 , wherein the trellis structure comprises a space-time code.
14. The method of claim 9 , further comprising:
converting each of the n symbols into baseband signals and multiplies each of the baseband signals by a selected, respective, PN bit sequence.
15. The method of claim 14 , wherein a first of the respective PN bit sequence is the same as a second of the respective PN bit sequence.
16. The method of claim 14 , wherein a first of the respective PN bit sequence is correlated to a second of the respective PN bit sequence.
17. A transmitter for transmitting a digital signal comprising:
n antennas;
a module that provides a signal to the n antennas and which employs a multi-level structured space-time code with an encoder at each level having a trellis structure, wherein the module selects branches of the trellis structure at different levels, and selects constellation points of a constellation based on labels of the branches that are selected and a set partitioning of the constellation, with the constellation points corresponding to the labels of the branches being transmitted over the n antennas simultaneously.
18. The transmitter of claim 17 , wherein:
the module selects the branches of the trellis structure, at each time t, branches of a form q t 1 q t 2 . . . q t n .