Polarization state techniques for wireless communications

• US 20040264592A1
• Filed: 07/31/2003
• Published: 12/30/2004
• Est. Priority Date: 12/30/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Corral, Celestino A., Sibecas, Salvador, Emami, Shahriar, Stratis, Glafkos, Rasor, Gregg
• Granted Patent: US 7,310,379 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2614 Peak power aspects

Abstract

Communication systems include a transmitter that modulates a radio signal transmitted from two differently polarized antennas during a state time in which a wave state of the radio signal conveys information and is based on one or more polarization states selected from a constellation of polarization states comprising at least three polarization states. The communication system includes a receiver that intercepts the radio signal by two differently polarized antennas during the state time, and demodulates the signal. The polarization states may identify user devices or may quantify a portion of the information intended for a user device.

Claims

1. A transmitter apparatus, comprising:

a mapper that maps sets of data into a series of reference polarization mapper output components (RP(s)) and a corresponding series of associated polarization mapper output components (AP(s)), wherein a combination of each pair of the reference and associated mapper output components defines one of a series of wave states (WS(s)), each based a polarization state (P_j) selected by the mapper from a constellation (P) of polarization states (P_{j,j=1 to J}) comprising at least two non-orthogonal states;

a first polarized antenna that transmits a reference radio signal that is modulated using the series of reference polarization mapper output component (RP(s)); and

a second polarized antenna, having a polarization different than the polarization of the first polarized antenna, that transmits an associated radio signal that is modulated using the series of associated polarization mapper output component (AP(s)).

2. The transmitter apparatus according to claim 1, further comprising:

an RP modulator that generates an RP modulated signal (RP(t)) from the component (RP(s));

an AP modulator that generates an AP modulated signal (AP(t)) from the component (AP(s)); and

RP and AP transmitters modulated respectively by the RP(t) and AP(t) modulated signals, that are each coupled to one of the first and second polarized antennas;

.

3. The transmitter apparatus according to claim 1, further comprising:

a table that stores the polarization states of the constellation (P) of polarization states.

4. The transmitter apparatus according to claim 1, wherein the mapper selects the polarization state P_j from a subset (P1) of the constellation of polarization states (P) corresponding to a first user device, based on a subset of a set of the data identified for delivery to the first user.

5. The transmitter apparatus according to claim 1, further comprising a pseudo noise generator, wherein the mapper selects the polarization state P_j based a pseudorandom number generated by the pseudo noise generator corresponding to a first user device.

6. The transmitter apparatus according to claim 1, wherein the mapper selects the polarization state P_j based on a subset of a set of data associated with a first user device and combines the subset of the set of data with a number derived from a pseudorandom number generated by a pseudorandom generator corresponding to the first user device.

7. The transmitter apparatus according to claim 1, wherein the mapper selects the polarization state (P_j) using a subset of a set of data.

8. The transmitter apparatus according to claim 1, wherein each polarization state (P_j) in the constellation (P) of polarization states comprises a reference polarization component (RP_i) and a corresponding associated polarization component (AP_j).

9. The transmitter apparatus according to claim 8, wherein each of the reference polarization mapper output components (RP(s)) is a reference polarization component (RP_j) from the constellation (P), and each of the associated polarization mapper output components (AP(s)) is the corresponding associated polarization component (AP_j) from the constellation (P).

10. The transmitter apparatus according to claim 8, wherein the first and second antennas are orthogonally polarized and complex coefficients of a reference polarization component (RP_j) and a corresponding associated polarization components (AP_j) in the constellation (P) are determined by:

RPI_j=cos γ

_j RPQ_j=0 API_j=sin γ

_j cos δ

_j APQ_j=sin γ

_j sin δ

_j

wherein RPI_j is an in-phase value and RPQ_j is a quadrature value of the reference polarization component (RP_j);

API_j is an in-phase value and APQ_j is a quadrature value of the associated polarization component (AP_j);

γ

_j is determined by arctan (E_2j/E_1j);

E_1j is a maximum instantaneous voltage in one of the antennas;

E_2j is a maximum instantaneous voltage in the other of the antennas; and

δ

_j is an instantaneous polarization-phase angle by which E_2j leads E_1j.

11. The transmitter apparatus according to claim 1, wherein the wave state (WS(s)) is determined by the mapper from the polarization state (P_j) selected from the constellation (P) of polarization states and an amplitude/absolute phase state (Ψ

_m) selected from a constellation (Ψ

) of amplitude/absolute phase states (Ψ

_{m,m=1 to M}).

12. The transmitter apparatus according to claim 11, wherein each amplitude/absolute phase state (Ψ

_m) in the constellation (Ψ

) of amplitude/absolute phase states is stored as an in-phase value (I<sub>Ψ

m</sub>) and a quadrature value (Q<sub>Ψ

m</sub>).

13. The transmitter apparatus according to claim 11, wherein the first and second antennas are substantially orthogonally polarized and each reference polarization mapper output component (RP(s)) and each corresponding associated polarization mapper output component (AP(s)) is determined by:

RPI(s_s=i)=|E_i| cos γ

_i cos φ

_i RPQ(s_s=i)=|E_i|cos γ

_i sin φ

_i API(s_s=i)=|E_i| sin γ

_i cos(φ

_i+δ

_i) APQ(s_s=i)=|E_i| sin γ

_i sin(φ

_i+δ

_i)

wherein RPI(s_s=i) is an in-phase value and RPQ(s_s=i) is a quadrature value of the reference polarization component of the wave state for state time i (WS(s_s=i));

API(s_s=i) is an in-phase value and APQ(s_s=i) is a quadrature value of the associated polarization component of the wave state (WS(s_s=i));

|E_i| is a magnitude of a selected state of the constellation (Ψ

) of amplitude/absolute phase states, φ

_i is a absolute phase of the selected state of the constellation (ψ

) of amplitude/absolute phase states;

γ

_i is an amplitude related parameter of a selected state of the constellation (P) of polarization states and δ

_i is an instantaneous polarization-phase angle of the selected state of the constellation (P) of polarization states.

14. The transmitter apparatus according to claim 11, wherein the polarization state (P_j) is selected based on a pseudorandom number generated by a generator corresponding to a user device and the amplitude/absolute phase state (Ψ

_m) is selected based on a subset of the set of data associated with the user device.

15. The transmitter apparatus according to claim 11, wherein the at least one amplitude/absolute phase state (Ψ

_m) is selected based on a pseudorandom number generated by a pseudorandom generator corresponding to a user device and the at least one polarization state (P_j) is selected based on a subset of the set of data associated with the user device.

16. The transmitter apparatus according to claim 1, wherein the at least two non-orthogonal polarization states comprise at least three polarization states.

17. A receiver apparatus, comprising:

first and second antennas that are differently polarized within a receive band;

a reference polarization (RP) receiver that converts radio energy intercepted by the first antenna to a baseband reference received polarized signal component (R′

P (t));

an associated polarization (AP) receiver that converts radio energy intercepted by the second antenna to a baseband associated received polarized signal component (A′

P(t));

a reference polarization demodulator that generates a series of received reference polarization components R′

P (s) from the baseband reference polarization signal (R′

P(t));

an associated polarization demodulator that generates a corresponding series of received associated polarization components A′

P(s) from the baseband associated polarization signal (A′

P(t)); and

a demapper that generates a most likely transmitted set of data by selecting, for each pair comprising a received reference polarization component R′

P(s) and the corresponding received associated polarization component A′

P(s), a most likely transmitted polarization state (P′

j) from a constellation of polarization states (P′

).

18. The receiver apparatus according to claim 17, wherein the demapper comprises:

a polarimetric filter that generates a best estimate of a desired signal using a dot product of a filter vector and the received reference polarization component R′

P(s) and the corresponding received associated polarization component A′

P(s); and

a state demapper that determines the most likely transmitted set of data from the best estimate of the desired signal.

19. The receiver apparatus according to claim 17, wherein the receiver measures characteristics of a channel and uses the characteristics to correct the received reference polarization component R′

P(s) and the corresponding received associated polarization component A′

P(s).

20. A method of radio communication, comprising:

modulating a radio signal transmitted from two differently polarized antennas during a state time in which a wave state of the radio signal conveys information and is based on one or more polarization states selected from a constellation of polarization states comprising at least three polarization states.

21. The method according to claim 20, wherein the wave state is generated by a reference transmit signal coupled to one of the two differently polarized antennas and an associated transmit signal coupled to the other of the two differently polarized antennas to produce the wave state having a combined polarization state that is based on the one or more polarization states.

22. The method according to claim 20, further comprising:

generating a plurality of frequency channels, wherein each frequency channel has a polarization state during the state time that is based on a portion of the information; and

combining the plurality of frequency channels by frequency multiplexing to form the wave state.

23. The method according to claim 20, further comprising:

generating a reference wave state modulation signal by a complex modulator using a reference wave state in-phase component and a reference wave state quadrature component;

generating an associated wave state modulation signal by a complex modulator using an associated wave state in-phase component and an associated wave state quadrature component; and

generating the wave state using the reference wave state modulation signal to modulate a reference transmit signal coupled to a first of the two differently polarized antennas and the associated wave state modulation signal to modulate a reference transmit signal coupled to a second of the two differently polarized antennas.

24. The method according to claim 20, further comprising:

maximizing a distance metric of the constellation of polarization states.

25. The method according to claim 24, wherein the distance metric is based on great circle distances between pairs of the at least three polarization states that are mapped using Poincaré

sphere coordinates.

26. The method according to claim 20, wherein the state time is a pilot state time and the wave state consists of a single predetermined polarization state selected from the constellation.

27. The method according to claim 20, further comprising:

generating the wave state by a combination of one or more combined modulation states, wherein each combined modulation state is formed from a polarization state and is determined at least partially from a portion of the information.

28. The method according to claim 27, wherein each of the combined modulation states is further formed from a non-polarization modulation state formed by combinations of one or more of a group of modulations consisting of amplitude, absolute phase, and frequency modulations.

29. The method according to claim 27, further comprising:

forming a non-polarization modulation state from a portion of the information associated with a user;

selecting as the polarization state a polarization state that is associated with a user device; and

combining the non-polarization modulation state with the selected polarization state to form a user identifiable data symbol.

30. The method according to claim 29, further comprising:

combining user identifiable data symbols for different user devices to determine the wave state.

31. The method according to claim 29, further comprising:

selecting the polarization state that is associated with a user device from the constellation of polarization states using one or more parameters associated with a set of user devices identified as potentially interfering user devices that are in a group of parameters that consists of received power levels at one or more of the user devices, a required carrier to interference power ratio, and a quantity of the potentially interfering user devices.

32. The method according to claim 29, further comprising:

selecting the polarization state that is associated with the user device from a subset of the constellation of polarization states, wherein the polarization states in the subset are determined by incremental changes to the polarization defining parameters of a pivot polarization state for the user device.

33. The method according to claim 32, further comprising:

selecting the polarization state that is associated with the user device using one or more parameters associated with a set of user devices identified as potentially interfering user devices that are in a group of parameters that consists of received power levels at one or more of the user devices, a required carrier to interference power ratio, and a quantity of the potentially interfering user devices.

34. The method according to claim 29, further comprising:

selecting the polarization state from the constellation of polarization states using one or more parameters associated with a user device that are in a group of parameters that consists of geographical location of the user device and a time of day.

35. The method according to claim 34, wherein the geographical location is determined by one of a location identification message received by the user device by wire or wirelessly, and manual entry, and a Global Positioning system receiver coupled to the user device.

36. The method according to claim 29, further comprising:

repeating the forming, selecting, and combining to form up to N user identifiable data symbols for each of a plurality of user devices;

combining a user identifiable data symbol for each of the plurality of user devices to form one of N sub-channel reference wave state components and one of N sub-channel associated wave state components; and

combining N sub-channel reference wave state components formed by repeating the combining of the user identifiable data symbol for each of the plurality of user devices, using Inverse Fast Fourier Transformation to generate complex reference and associated wave state coefficients; and

generating the modulated radio signal using the complex reference wave state coefficients and complex associated wave state coefficients.

37. The method according to claim 29, wherein the state time is during a data transferring period of a carrier-sense multiple access, collision avoidance communication system and user identifiable data symbols for a plurality of user devices are transmitted simultaneously during the state time.

38. The method according to claim 29, wherein predetermined polarization states associated with each of one or more user devices are identified to contending user devices during a contention period of the carrier-sense multiple access, collision avoidance communication system.

39. The method according to claim 20, further comprising:

assigning a polarization state of the constellation of polarization states to a polarization channel.

40. The method according to claim 39, further comprising:

assigning the polarization channel to a user device.

41. The method according to claim 40, further comprising:

assigning other polarization states of the constellation of polarization states to other polarization channels; and

assigning at least one of the other polarization channels to the user device according to a bandwidth assigned to the user device.

42. The method according to claim 20, wherein the wave state is one of N sequential wave states, further comprising:

determining a non-polarization modulation state that quantifies a portion of the information that is associated with a user device, the non-polarization modulation state having a duration of N state times;

generating a sequence of N pseudorandom numbers associated with the user device;

selecting a sequence of N polarization modulation states from the constellation using the sequence of N pseudorandom numbers; and

generating each of the N wave states by combining one of the sequence of N polarization modulation states with the non-polarization modulation state.

43. The method according to claim 20, wherein the wave state is a polarization state selected from the constellation of polarization states using a chipset of a data symbol that is a portion of the information, further comprising:

generating a pseudorandom number associated with the user device

selecting a polarization state from the constellation using a logical combination of the pseudorandom number and the chipset; and

generating the wave state as the polarization state.

44. The method according to claim 20, further comprising:

selecting a first polarization state from the constellation using a pseudorandom number that is associated with a first user device;

selecting a first frequency channel associated with the first user device from a set of frequency channels;

forming a first non-polarization state based on a portion of the information associated with a first user device using one of amplitude modulation, absolute phase modulation, and amplitude/absolute phase modulation; and

combining the first polarization state, the first frequency channel, and the first non-polarization modulation state to form a first combined modulation state; and

forming the wave state from the first combined modulation state.

45. The method according to claim 44, further comprising:

selecting a second polarization state from the constellation using a pseudorandom number that is associated with a second user device;

forming a second non-polarization state based on a portion of the information associated with the second user device using one of amplitude modulation, absolute phase modulation, and amplitude/absolute phase modulation;

combining the second polarization state and the second non-polarization modulation state with the first frequency channel to form a second combined modulation state; and

forming the wave state by a combination of the first and second combined modulation states.

46. The method according to claim 20, further comprising:

selecting a first polarization state from the constellation using a pseudorandom number that is associated with a first user device;

selecting a first time division multiplexing time slot associated with the first user device from a set of time slots for transmitting the wave state;

forming a first non-polarization state modulation based on a portion of the information associated with the first user device, using one of amplitude modulation, absolute phase modulation, and amplitude/absolute phase modulation;

combining the first polarization state and the first non-polarization modulation state to form a first combined modulation state; and

transmitting the first combined modulation state during the first time slot.

47. The method according to claim 46, further comprising:

selecting a second polarization state from the constellation using a pseudorandom number that is associated with a second user device;

forming a second non-polarization state modulation based on a portion of the information associated with the second user device, using one of amplitude modulation, absolute phase modulation, and amplitude/absolute phase modulation; and

combining the second polarization state and the second non-polarization modulation state to form a first combined modulation state;

combining the first and second combined modulation states; and

transmitting the first and second combined modulation states during the first time slot.

48. The method according to claim 20, further comprising:

selecting a chip from each of M data symbols intended for corresponding M user devices;

performing M logical operations, each being a logical operation of an orthogonal function value associated with each of the M user devices and the chip from the corresponding user device;

combining results of the M logical operations; and

selecting a polarization states using the combined results.

49. The method according to claim 20, further comprising:

selecting a polarization state from the constellation of polarization states using a first pseudorandom number associated with a user device;

selecting a frequency channel from a set of frequency channels using a second pseudorandom number associated with the user device;

forming a non-polarization modulation state from a portion of the information associated with the user device using one of amplitude modulation, absolute phase modulation, and amplitude/absolute phase modulation; and

combining the polarization state, the frequency state, and the non-polarization modulation state to form the wave state.

50. The method according to claim 20, further comprising:

determining a non-polarization modulation state that quantifies a portion of the information that is associated with a user device, that is to be transmitted within a frame having a duration that is a multiple of the state time;

generating a first pseudorandom number associated with the user device;

selecting a polarization modulation state using the first pseudorandom number;

generating a second pseudorandom number associated with the user device;

determining the wave state by combining the selected polarization modulation state with the non-polarization modulation state; and

transmitting the wave state at a state time within the frame selected by using the second pseudorandom number.

51. The method according to claim 20, further comprising forming the wave state based on a logical operation performed on a stored sequence of combined modulation states, wherein the operation is based on at least one previous combined modulation state that includes a polarization state.

52. A method of radio communication, comprising:

demodulating a radio signal intercepted by two differently polarized antennas during a state time in which a wave state that conveys information is based on one or more polarization states selected from a constellation of at least three polarization states.

53. The method according to claim 52, wherein the received desired combined modulation states comprise memory encoded combined modulation states based on an encoded combined modulation state and other encoded combined modulation state, further comprising:

storing the received best estimated memory encoded combined modulation state, which is used with previously stored received best estimated memory encoded combined modulation states to determine in a maximum likelihood estimation process a most likely encoded combined modulation state that represents the combined modulation state.

56. The method according to claim 53, further comprising:

determining a most likely transmitted combined modulation state using a minimum distance of a best estimated received combined modulation state and states of a constellation of all possible desired combined modulation states.

57. The method according to claim 53, further comprising:

determining a most likely transmitted polarization state using a minimum distance of a best estimated received polarization state and states of a polarization constellation of all possible desired polarization states;

determining a best estimate of a non-polarization modulation state using the most likely transmitted polarization state; and

determining a most likely transmitted non polarization state using a minimum distance of the best estimate of a received non-polarization modulation state and states of a non-polarization constellation comprising all possible desired non-polarization states.

58. The method according to claim 53, wherein the desired and undesired combined modulation signals are received at a receiver that determines most likely transmitted state from radios signals received simultaneously from independent first and second user devices.

59. The method according to claim 53, wherein the desired and undesired combined modulation signals are received at a receiver that determines a most likely transmitted state from a radio signal that, as transmitted, includes the desired and undesired combined modulation signals.

60. The method according to claim 53, further comprising:

determining the polarization state of the undesired combined modulated signal by using a polarization state received in a pilot polarization signal associated with the second user device.

54. A method for receiving a radio signal, comprising:

generating a reference received signal (S_H(t)) and an associated received signal (S_V(t)) by intercepting a radio signal comprising a desired combined modulated state associated with a first user device combined with an undesired combined modulated state associated with a second user device, wherein the desired combined modulated signal comprises a desired polarization state associated with the first user device and the undesired modulated signal comprises an undesired polarization state associated with the second user device, and wherein the radio signal is modified by channel characteristics, and wherein the interception performed by two differently polarized antennas, and wherein the desired and undesired polarization states have been selected from a constellation of polarization states comprising at least three polarization states.

55. The method according to claim 54, further comprising:

generating complex reference received state components from the reference received signal (S_H(t)) and the associated received signal (S_V(t)) and complex associated received state components for the channel characteristics;

generating complex components of a cancellation state that is orthogonally polarized to a polarization state of the undesired combined modulated radio signal;

generating a complex dot product of the complex received state components and the complex components of the cancellation state; and

polarimetrically processing the complex dot product of the corrected complex received state components and the complex components of the cancellation state to determine a best estimate of the desired combined modulation state.