Transmit diversity method applied to a transmitting system and transmitting system having multi-transmission paths thereof

• US 8,897,392 B2
• Filed: 11/09/2010
• Issued: 11/25/2014
• Est. Priority Date: 11/13/2009
• Status: Active Grant

• Current Assignee: Realtek Semiconductor Corp.
• Original Assignee: Realtek Semiconductor Corp.
• Inventors: Lin, Yu-Nan, Yen, Kuang-Yu
• Primary Examiner(s): Neff, Michael
• Assistant Examiner(s): Bolourchi, Nader
• Application Number:
  US12/942,973
• Publication Number:
  US 20110116575A1
• Time in Patent Office: 1,477 Days
• Field of Search: 375/299
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0608 Antenna selection according to transmission parameters
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only

Abstract

A transmit diversity method applied to a transmitting system includes the steps of: receiving a serial stream, and transforming the serial stream into a plurality of parallel streams, wherein each parallel stream is carried by a corresponding sub-carrier; and in light of each sub-carrier, selecting a single transmission path from at least two transmission paths of the transmitting system so as to transmit the parallel stream carried by the sub-carrier. The transmit diversity method further includes the step of: dividing the plurality of parallel streams carried by the sub-carries into M groups, wherein the parallel streams belonging to the same group are transmitted via selecting the same transmission path.

Claims

1. A transmit diversity method applied to a transmitting system, the transmitting system comprising at least two transmission paths, each of the at least two transmission paths has a channel coefficient, the method includes the steps of:

receiving a serial stream, and transforming the serial stream into a plurality of parallel streams, wherein each parallel stream is carried by a corresponding sub-carrier; and

in light of each sub-carrier, selecting a single transmission path from the at least two transmission paths of the transmitting system by comparing energies of a plurality of channel coefficients corresponding to the at least two transmission paths on the sub-carrier, so as to transmit the parallel stream carried by the sub-carrier;

wherein the each channel coefficient is defined by y=h*s+N, where y is a receiving signal of the sub-carrier on the corresponding transmission path, h is the channel coefficient, s is a transmitting signal of the sub-carrier, and N is noise.

2. The transmit diversity method of claim 1, wherein the step of selecting the single transmission path from the at least two transmission paths so as to transmit the parallel stream carried by the sub-carrier comprises:

comparing energies of a plurality of channel coefficients corresponding to the at least two transmission paths on a k^th sub-carrier, where k=1, 2, . . . ; and

selecting a designated transmission path having a maximum energy of the channel coefficient from the at least two transmission paths so as to transmit the parallel stream carried by the k^th sub-carrier.

3. The transmit diversity method of claim 2, wherein the step of selecting the designated transmission path having the maximum energy of the channel coefficient from the at least two transmission paths can be mathematically expressed as:

4. The transmit diversity method of claim 1, wherein each of the at least two transmission paths has a channel coefficient, and the step of selecting the single transmission path from the at least two transmission paths so as to transmit the parallel stream carried by the sub-carrier comprises:

when an energy of the channel coefficient of a first transmission path on a k^th sub-carrier among the at least two transmission paths is greater than a threshold, selecting the first transmission path to transmit the parallel stream carried by the k^th sub-carrier, where k=1, 2, . . . ; and

when the energy of the channel coefficient of the first transmission path on the k^th sub-carrier is smaller than the threshold, selecting a second transmission path to transmit the parallel stream carried by the k^th sub-carrier.

5. The transmit diversity method of claim 1, further comprising:

dividing the plurality of parallel streams carried by the sub-carries into M groups, where M=1, 2, . . . ;

wherein the parallel streams belonging to the same group are transmitted via selecting the same transmission path.

6. The transmit diversity method of claim 5, wherein each of the at least two transmission paths has a channel coefficient, and the step of selecting the single transmission path from the at least two transmission paths so as to transmit the parallel stream carried by the sub-carrier comprises:

comparing summations of energies of a plurality of channel coefficients corresponding to the at least two transmission paths on all sub-carries belonging to a m^th group, where m=1, 2, . . . ; and

selecting a designated transmission path having a maximum summation of energies of the channel coefficients from the at least two transmission paths so as to transmit the parallel streams carried by the sub-carriers belonging to the m^th group.

7. The transmit diversity method of claim 6, wherein the step of selecting the designated transmission path having the maximum summation of energies of the channel coefficients from the at least two transmission paths can be mathematically expressed as:

8. The transmit diversity method of claim 5, wherein each of the at least two transmission paths has a channel coefficient, and the step of selecting the single transmission path from the at least two transmission paths so as to transmit the parallel stream carried by the sub-carrier comprises:

when a summation of energies of the channel coefficient of a first transmission path among the at least two transmission paths on all sub-carriers belonging to a m^th group is greater than a threshold, selecting the first transmission path to transmit the parallel streams carried by the sub-carriers belonging to the m^th group, where m=1, 2, . . . ; and

when the summation of energies of the channel coefficient of the first transmission path on all sub-carriers belonging to the m^th group is smaller than the threshold, selecting a second transmission path to transmit the parallel streams carried by the sub-carriers belonging to the m^th group.

9. The transmit diversity method of claim 1, further comprising:

dividing the plurality of parallel streams carried by the sub-carries into an identical group;

wherein all of the parallel streams are transmitted via selecting the same transmission path.

10. The transmit diversity method of claim 9, wherein the step of selecting the single transmission path from the at least two transmission paths so as to transmit the parallel stream carried by the sub-carrier comprises:

comparing summations of energies of all received signals of each transmission path among the at least two transmission paths; and

selecting a designated transmission path having a maximum summation of energies of the received signals from the at least two transmission paths so as to transmit the parallel streams carried by all of the sub-carriers.

11. The transmit diversity method of claim 10, wherein the step of selecting the designated transmission path having a maximum summation of energies of the received signals from the at least two transmission paths can be mathematically expressed as:

12. The transmit diversity method of claim 1, being applied to an orthogonal frequency-division multiplexing (OFDM) transmission.

13. A transmitting system having multi-transmission paths, comprising:

a serial-to-parallel transform circuit, for receiving a serial stream, and for transforming the serial stream into a plurality of parallel streams, wherein each parallel stream is carried by a corresponding sub-carrier;

at least two transmission paths, wherein each of the at least two transmission paths has a channel coefficient; and

a transmission path selector, coupled between the serial-to-parallel transform circuit and the at least two transmission paths;

wherein in light of each sub-carrier, the transmission path selector selects a single transmission path from the at least two transmission paths of the transmitting system by comparing energies of a plurality of channel coefficients corresponding to the at least two transmission paths on the sub-carrier, so as to transmit the parallel stream carried by the sub-carrier;

wherein the each channel coefficient is defined by y=h*s+N, where y is a receiving signal of the sub-carrier on the corresponding transmission path, h is the channel coefficient, s is a transmitting signal of the sub-carrier, and N is noise.

14. The transmitting system of claim 13, wherein the transmission path selector comprises:

a computing unit, for comparing energies of a plurality of channel coefficients corresponding to the at least two transmission paths on a k^th sub-carrier, in order to generate a comparison result, where k=1, 2, . . . ; and

a selecting unit, coupled to the computing unit, for selecting a designated transmission path having a maximum energy of the channel coefficient from the at least two transmission paths according to the comparison result, so as to transmit the parallel stream carried by the k^th sub-carrier.

15. The transmitting system of claim 14, wherein the computing unit and the selecting unit of the transmission path selector can be mathematically expressed as:

16. The transmitting system of claim 13, wherein each of the at least two transmission paths has a channel coefficient, and the transmission path selector comprises:

a determining unit, for determining whether an energy of the channel coefficient of a first transmission path on a k^th sub-carrier among the at least two transmission paths is greater than a threshold, in order to generate a determining result, where k=1, 2, . . . ; and

a selecting unit, coupled to the determining unit, for selecting to use the first transmission path or a second transmission path to transmit the parallel stream carried by the k^th sub-carrier according to the determining result;

wherein when the determining result indicates that the energy of the channel coefficient of the first transmission path on the k^th sub-carrier is greater than the threshold, the selecting unit selects the first transmission path to transmit the parallel stream carried by the k^th sub-carrier; and

when the determining result indicates that the energy of the channel coefficient of the first transmission path on the k^th sub-carrier is smaller than the threshold, the selecting unit selects the second transmission path to transmit the parallel stream carried by the k^th sub-carrier.

17. The transmitting system of claim 13, further comprising:

a group dividing circuit, coupled between the serial-to-parallel transform circuit and the transmission path selector, for dividing the plurality of parallel streams carried by the sub-carries into M groups, where M=1, 2, . . . ;

wherein the parallel streams belonging to the same group are transmitted via selecting the same transmission path.

18. The transmitting system of claim 17, wherein each of the at least two transmission paths has a channel coefficient, and the transmission path selector comprises:

a computing unit, for comparing summations of energies of a plurality of channel coefficients corresponding to the at least two transmission paths on all sub-carries belonging to a m^th group, in order to generate a comparison result, where m=1, 2, . . . ; and

a selecting unit, coupled to the computing unit, for selecting a designated transmission path having a maximum summation of energies of the channel coefficients from the at least two transmission paths according to the comparison result, so as to transmit the parallel streams carried by the sub-carriers belonging to the m^th group.

19. The transmitting system of claim 18, wherein the computing unit and the selecting unit of the transmission path selector can be mathematically expressed as:

20. The transmitting system of claim 17, wherein each of the at least two transmission paths has a channel coefficient, and the transmission path selector comprises:

a determining unit, for determining whether a summation of energies of the channel coefficient of a first transmission path among the at least two transmission paths on all sub-carriers belonging to a m^th group is greater than a threshold, in order to generate a determining result, where m=1, 2, . . . ; and

a selecting unit, coupled to the determining unit, for selecting to use the first transmission path or a second transmission path to transmit the parallel streams carried by the sub-carriers belonging to the m^th group according to the determining result;

wherein when the determining result indicates that summation of energies of the channel coefficient of the first transmission path on all sub-carriers belonging to the m^th group is greater than the threshold, the selecting unit selects the first transmission path to transmit the parallel streams carried by the sub-carriers belonging to the m^th group; and

when the determining result indicates that summation of energies of the channel coefficient of the first transmission path on all sub-carriers belonging to the m^th group is smaller than the threshold, the selecting unit selects the second transmission path to transmit the parallel streams carried by the sub-carriers belonging to the m^th group.

21. The transmitting system of claim 13, further comprising:

a group dividing circuit, coupled between the serial-to-parallel transform circuit and the transmission path selector, for dividing the plurality of parallel streams carried by the sub-carries into an identical groups;

wherein all of the parallel streams are transmitted via selecting the same transmission path.

22. The transmitting system of claim 21, wherein the transmission path selector comprises:

a computing unit, for comparing summations of energies of all received signals of each transmission path among the at least two transmission paths, in order to generate a comparison result; and

a selecting unit, coupled to the computing unit, for selecting a designated transmission path having a maximum summation of energies of the received signals from the at least two transmission paths according to the comparison result, so as to transmit the parallel streams carried by all of the sub-carriers.

23. The transmitting system of claim 22, wherein the computing unit and the selecting unit of the transmission path selector can be mathematically expressed as:

24. The transmitting system of claim 13, being applied to an orthogonal frequency-division multiplexing (OFDM) transmission.