Millimetre wave(mmw) communication system and method using multiple recieve and transmit antennas

• US 20040067775A1
• Filed: 02/19/2003
• Published: 04/08/2004
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: Millimetrix Broadband Networks Limited
• Original Assignee: Millimetrix Broadband Networks Limited
• Inventors: Dalal, Hezi, Steinberg, Yossi
• Granted Patent: US 7,272,408 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/084 Equal gain combining, only phase adjustments antenna beam scanning or forming by phase or amplitude control H01Q3/26, e.g. phased arrays
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

The spectral efficiency of a millimeter wave (MMW) communication system (100) is enhanced by using multiple receive (116a, 116b . . . 116r) and transmit antenna elements (114a, 114b . . . 114t), arranged in arrays. Each of the receive antenna elements (116a, 116b . . . 116r) receives the signals transmitted from all of the transmit antenna elements (114a, 114b . . . 114t) with different degrees of phase shift. The signals which are received are combined in a one channel and substantially cancels out all others, thereby achieving channel separation. The spectral efficiency increases linearly with the number of antenna elements (per array). The spectral efficiency of an array can further be increased by using dual polarization antenna elements and techniques.

Claims

1. A millimeter-wave (MMW) communication system comprising:

a transmit subsystem for providing signals to a plurality of transmit antenna elements; and

a receive subsystem for receiving the signals from a plurality of receive antenna elements;

wherein the transmit and receive antenna elements are physically arranged so that each of the receive antenna elements receives the signals transmitted from all of the transmit antenna elements with differing degrees of phase shift.

2. System, according to claim 1, wherein:

the transmit antenna elements are arranged in a transmit array;

the receive antenna elements are arranged in a receive array; and

each of the receive antenna elements receives signals from all of the transmit antenna elements with phase shifts incurred in relation to their positions in the respective receive and transmit arrays.

3. System, according to claim 2, wherein:

the transmit array and the receive array each have the same number of antenna elements; and

the transmit antenna elements are arranged with a geometry mirroring that of the receive antenna elements.

4. A system, according to claim 1, wherein:

for a given one of the transmit antenna elements, a one of the receive antenna elements is a corresponding antenna element which is positioned directly across from, aligned with, and aimed at the given one of the transmit antenna elements, and the remaining receive antenna elements are non-corresponding antenna elements;

there is an overall link length (L) between the transmit antenna elements and the receive antenna elements;

there are direct link lengths (L_k,k) between corresponding antenna elements;

there are cross-link lengths (L_k,l) between non-corresponding antenna elements;

the cross-link lengths (L_k,l) are longer than the direct link lengths by an amount dependent upon the link length (L) and the physical geometry of the transmit and receive antenna elements.

5. System, according to claim 1, wherein:

the transmit subsystem comprises;

a transmit shaping section for receiving a plurality of transmit data streams and producing a plurality of transmit streams;

a transmitter section providing the plurality of transmit streams as the signals to the transmit antenna elements;

the receive subsystem comprises;

a receiver section for receiving and boosting the signals from the receive antenna elements and providing a plurality of receive streams;

an equalizer section for receiving the plurality of receive streams, separating the signals from the transmit antennas from one another, and providing a plurality of received data streams corresponding to the plurality of transmit data streams.

6. System, according to claim 5, wherein:

the equalizer section equalizes and compensates the receive streams by isolating and separating components of the transmitted signals therein based on their relative phase difference to produce the received data streams corresponding to the transmit data streams.

7. System, according to claim 5, wherein:

each of the plurality of transmit data streams comprises an independent stream of symbols to be transmitted;

each of the resulting plurality of independent streams of symbols are convolved with a transmission pulse to form a composite signal and are multiplexed into the plurality of transmit streams via a transmit shaping matrix (Q) in the transmit shaping section.

8. System, according to claim 7, wherein:

the composite signals received by the receive antenna elements is represented in complex baseband by the matrix equation y=F_rTF_tQa+n wherein;

y is an r×

1 complex vector representing the composite received signal as represented on the plurality of receive streams;

a is an s×

1 vector of information symbols representing data encoded onto the plurality of transmit data streams;

T is a two-dimensional matrix representing composite complex transfer characteristics of a transmission path between the receive and transmit antenna elements, and elements (T_k,l) of the matrix T represent the transfer characteristics of individual transmission paths between individual receive antenna elements and individual transmit antenna elements;

Q is a t×

s transmit shaping matrix representing the manner in which symbol data on the plurality of transmit data streams modulates the transmit pulse and is distributed across the plurality of transmit streams;

n is an r×

1 complex Gaussian noise vector representing noise experienced at each of the plurality of receive antenna elements; and

F_t and F_r are diagonal matrices representing the gains of the individual transmit and receive antenna elements, respectively.

9. System, according to claim 8, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (a) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing (d) between adjacent ones of the receive antenna elements;

the transmit shaping matrix. (Q), an inter-element spacing (d) and a geometry of the transmit and receive antenna elements are determined as a function of the carrier frequency (f_c) and link length (L).

10. System according to claim 9, wherein:

the parameters of the transmit shaping matrix (Q) are determined so that a resultant equivalent transfer matrix F_rTF_tQ can be inverted readily without introducing significant sources of error.

11. System according to-claim 9, wherein:

the transmit shaping matrix (Q) and an inter-element spacing (d) and a geometry of the transmit and receive antenna elements are selected to take maximum advantage of phase differences over transmission paths of differing lengths to achieve channel discrimination with minimal signal-to-noise ratio (SNR) degradation.

12. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 23 GHz;

the link length (L) is approximately 3 km; and

the spacing (d) is approximately 4.42 m.

13. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 23 GHz;

the link length (L) is approximately 3 km; and

the spacing (d) is approximately 3.6 m.

14. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 23 GHz;

the link length (L) is approximately 3 km; and

the spacing (d) is approximately 5.1 m.

15. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 38 GHz;

the link length (L) is approximately 3 km; and

the spacing d is approximately 3.45 m.

16. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L) between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 38 GHz;

the link length (L) is approximately 2 km; and

the spacing (d) is approximately 2.75 m.

17. System, according to claim 1, wherein:

the signals are transmitted at a carrier frequency (f_c);

there is a link length (L);

between the transmit antenna elements and the receive antenna elements;

there is an inter-element spacing (d) between adjacent ones of the transmit antenna elements, and a substantially equal inter-element spacing d between adjacent ones of the receive antenna elements;

the carrier frequency (f_c) is approximately 38 GHz;

the link length (L) is approximately 1 km; and

the spacing (d) is approximately 1.99 m.

18. System, according to claim 1, wherein:

there are two transmit antenna elements (214) arranged in a transmit array, and separated by a distance (d);

there are two receive antenna elements (216), arranged in a receive array, and separated by a distance substantially equal to the distance (d);

there is an overall link length (L) representing a linear distance between the transmit and receive arrays;

a direct link distance between a first of the two transmit antenna elements and a first of the two receive antenna elements is substantially equal to a direct link distance between a second of the two transmit antenna elements and a second of the receive antenna elements;

a cross-link distance between the first of the two transmit antenna elements and the second of the two receive antenna elements is substantially equal to a cross-link distance between a second of the two transmit antenna elements and a first of the receive antenna elements;

the distance (a) is chosen so that the cross-link lengths are longer than the direct link lengths by an amount substantially equal to one quarter of a carrier wavelength of the signals.

19. System, according to claim 1, wherein:

a transmit array comprises three linearly arranged transmit antenna elements, and

a receive array comprises three linearly arranged receive antenna elements.

20. System, according to claim 1, wherein:

a transmit antenna array comprises three co-planar transmit antenna elements; and

a receive antenna array comprises three co-planar receive antenna elements.

21. System, according to claim 20, wherein:

the transmit antenna elements are arranged in an equilateral triangular configuration; and

the receive antenna elements are arranged in an equilateral triangular configuration.

22. System, according to claim 1, wherein:

the transmit antenna array comprises four co-planar transmit antenna elements; and

the receive antenna array comprising four co-planar receive antenna elements.

23. System, according to claim 22, wherein:

the transmit antenna elements are arranged in a square configuration; and

the receive antenna elements are arranged in a square configuration.

24. A millimeter-wave (MMW) communication system, according to claim 1, wherein the receive subsystem further comprises:

an equalizer section comprising a first equalizer, a second equalizer, a third equalizer, and a fourth equalizer, each having an input and an output;

the inputs of the first and third equalizers are connected to receive a first input stream from a first receive antenna element;

the inputs of the second and fourth equalizers are connected to receive a second input stream from a second receive antenna element;

the outputs of the equalizers are connected to corresponding first, second, third and fourth phase locked loops, each having an output;

the outputs of the first and second phase locked loops are summed in a first summer, said summer having an output; and

the outputs of the third and fourth phase locked loops are summed in a second summer, said summer having an output.

25. System, according to claim 24, further comprising:

a fifth phase locked loop connected to the output of the first summer; and

a sixth phase locked loop connected to the output of the second summer.

26. System, according to claim 24, wherein:

the first and second equalizers correspond to first and second elements, respectively, of an equalization matrix W that inverts a composite transmission channel between the transmit antenna elements and the receive antenna elements.

27. System, according to claim 24, wherein:

the first and second equalizers isolate and separate a first symbol stream from two receive streams; and

the third and fourth equalizers isolate and separate a second symbol stream from the two receive streams.

28. A millimeter-wave (MMW) communication system, according to claim 1, wherein the receive subsystem further comprises:

an equalizer section comprising a first phase locked loop, a second phase locked loop, a third phase locked loop, and a fourth phase locked loop, each having an input and an output;

the inputs of the first and third phase locked loop are connected to receive a first input stream from a first receive antenna element;

the inputs of the second and fourth phase locked loop are connected to receive the second input stream from a second receive antenna element;

the outputs of the phase locked loop are connected to corresponding first, second, third and fourth equalizers, each having an output;

the outputs of the first and second equalizers are summed in a first summer, said summer having an output; and

the outputs of the third and fourth equalizers are summed in a second summer, said summer having an output.

29. System, according to claim 28, further comprising:

a fifth phase locked loop connected to the output of the first summer; and

a sixth phase locked loop connected to the output of the second summer.

30. A millimeter-wave (MMW) communication system, according to claim 1, wherein the receive subsystem further comprises:

a first equalizer, a second equalizer, a third equalizer, and a fourth equalizer, each having an input and an output;

the input of the first equalizer is connected to receive a first input stream from a first receive antenna element;

the input of the second equalizer is connected to receive a second input stream from a second receive antenna element;

the input of the third equalizer is connected to receive a third input stream from a third receive antenna element;

the input of the fourth equalizer is connected to receive a fourth input stream from a fourth receive antenna element;

the outputs of the equalizers are connected to corresponding first, second, third and fourth phase locked loops, each having an output;

the outputs of the first, second, third and fourth phase locked loops are summed in a summer having an output; and

31. System, according to claim 30, further comprising:

a fifth phase locked loop connected to the output of the summer.

32. A millimeter-wave (MMW) communication system, according to claim 1, wherein the receive subsystem further comprises:

a first phase locked loop, a second phase locked loop, a third phase locked loop, and a fourth phase locked loop, each having an input and an output,

the input of the first phase locked loop is connected to receive a first input stream from a first receive antenna element;

the input of the second phase locked loop is connected to receive a second input stream from a second receive antenna element;

the input of the third phase locked loop is connected to receive a third input stream from a third receive antenna element;

the input of the fourth phase locked loop is connected to receive a fourth input stream from a fourth receive antenna element;

the outputs of the phase locked loop are connected to corresponding first, second, third and fourth equalizers, each having an output;

the outputs of the first, second, third and fourth equalizers are summed in a summer having an output; and

33. System, according to claim 32, further comprising:

a fifth phase locked loop connected to the output of the summer.

34. A method of increasing spectral efficiency in a millimeter-wave (MMW) communication system;

comprising;

providing a transmit array comprising at least two transmit antenna elements;

providing a receive array comprising corresponding at least two receive antenna elements;

arranging the transmit and receive antenna elements so that each of the receive antenna elements receives the signals transmitted from all of the transmit antenna elements with differing degrees of phase shift.

35. Method, according to claim 34, further comprising:

combining the signals received by the receive antenna elements in a manner which emphasizes one channel and substantially cancels out all others, thereby achieving channel separation.

36. Method, according to claim 34, further comprising:

choosing a geometry for the antenna elements so that the differences in link length between individual transmit antenna elements and individual receive antenna elements are all related to a carrier wavelength of the signals.

37. Method, according to claim 34, further comprising:

maintaining a distance between the transmit antenna elements and the receive antenna elements of approximately 0.5-6 km.