Granted Patent B2

US 8,179,779 · App. 12/586,823 · Granted May 15, 2012

Abstract

Claims (65)

1. A method for characterizing state information of the propagation channel in a cell having edges adjacent to other cells of a cellular network in which at least three non-overlapping sets U, V, W of pilot signals are defined, comprising:

receiving a pilot signal, belonging to the set U, transmitted over a wireless radiofrequency propagation channel from at least one mobile station belonging to the cellular network; and

in a processor, deriving information about the propagation channel from the transmitted and received pilot signal using knowledge of the pilot signals in the set U, wherein:

in a representation of the pilot signals as vectors, each of the sets U, V, and W consists of mutually orthogonal elements;

each of U, V, and W includes at least six peripheral elements and at least three central elements;

the six peripheral elements of each set U, V, W are orthogonal to at least three peripheral elements of each of the other two sets; and

the received pilot signal is a peripheral element of U if the transmitting mobile station is near an edge of the cell, but is a central element of U if the transmitting mobile station is not near an edge of the cell.

2. The method of claim 1 , further comprising, in a processor, precoding a signal and transmitting the signal for reception by a selected mobile station, wherein the precoding step uses at least some of the information about the propagation channel derived from the transmitted and received pilot signal.

3. The method of claim 1 , wherein:

each of the sets U, V, and W consists of nine mutually orthogonal signal vectors, and each said vector has nine components; and

each of the sets U, V, and W is either: a set, of vectors, having the property that all vector components are of the form e 2nπi/3 , wherein n=0, 1, or 2; or a set, of vectors, derivable from a set having said property by applying a common scale factor, phase shift, or unitary rotation to all vectors in the set having said property.

4. A method to be carried out by a base station in a cellular network having a reuse factor of 3 for uplink pilot signals to be used for channel measurement, said base station belonging to a cell in a reuse class A that is one of three reuse classes A, B, and C, wherein said cell may have one or more edges adjacent to cells of class B and simultaneously one or more edges adjacent to cells of class C, the method comprising:

classifying each mobile station currently within the cell served by the base station as a center mobile, a peripheral mobile near a class B cell, or a peripheral mobile near a class C cell;

allocating a set of mutually orthogonal pilot signals to the mobile stations such that each peripheral mobile station adjacent to a class B cell is allocated a pilot signal that is also orthogonal to some class B pilot signals, and each peripheral mobile station adjacent to a class C cell is allocated a pilot signal that is also orthogonal to some class C pilot signals; and

transmitting, to each said mobile station within the served cell, a signal designating at least one pilot signal that has been allocated to that mobile station.

5. The method of claim 4 , wherein:

three sets U={u i }, V={v i }, W={w i } of pilot signals are defined;

one of said sets is allocated to each respective class of cells;

the pilot signals in each of the sets U, V, W viewed as vectors constitute an orthogonal basis;

at least three of the elements u i of U form an orthogonal basis with at least six of the elements v i of V;

at least three other of the elements u i of U form an orthogonal basis with at least six of the elements w i of W;

said at least six elements u i of U form an orthogonal basis with at least three of the elements v i of V and form another orthogonal basis with at least three of the elements w i of W;

at least three of the elements of V form an orthogonal basis with at least six of the elements of W; and

at least three of the elements of W form an orthogonal basis with at least six of the elements of V.

6. A method to be carried out by a mobile station belonging to a cellular network in which at least three: non-overlapping sets U, V, W of pilot signals are defined, comprising:

receiving a signal from a base station designating a pilot signal of a set U, which is one of said three sets U, V, W, to be selected for transmission;

selecting the designated pilot signal; and

transmitting the designated pilot signal to the base station for the base station to derive, using a processor, information therefrom that characterizes the propagation channel between the mobile station and the base station using knowledge of the pilot signals in the set U; wherein:

in a representation of the pilot signals as vectors, each of the sets U, V, and W consists of mutually orthogonal elements;

each of U, V, and W includes at least six peripheral elements and at least three central elements;

the six peripheral elements of each set U, V, W are orthogonal to at least three peripheral elements of each of the other two sets; and

the transmitted pilot signal is a peripheral element of U if the transmitting mobile station is near an edge of the cell, but is a central element of U if the transmitting mobile station is not near an edge of the cell.

7. The method of claim 6 , wherein:

each of the sets U, V, and W consists of nine mutually orthogonal signal vectors, and each said vector has nine components; and

each of the sets U, V, and W is either: a set, of vectors, having the property that all vector components are of the form e 2nπi/3 , wherein n=0, 1, or 2; or a set, of vectors, derivable from a set having said property by applying a common scale factor, phase shift, or unitary rotation to all vectors in the set having said property.

8. The method of claim 6 , wherein:

at least three of the elements of V form an orthogonal basis with at least six of the elements of W; and

at least three of the elements of W form an orthogonal basis with at least six of the elements of V.

9. Base station apparatus configured for characterizing state information of the propagation channel in a cell having edges adjacent to other cells of a cellular network in which at least three non-overlapping sets U, V, W of pilot signals are defined, comprising:

a circuit configured to receive a pilot signal belonging to a set U that is one of the three sets U, V, W of pilot signals, said pilot signal being transmitted over a wireless radiofrequency propagation channel from at least one mobile station belonging to the cellular network; and

a processor configured to derive information about the propagation channel from the received pilot signal using stored knowledge of the pilot signals in the set U, wherein:

in a representation of the pilot signals as vectors, each of the sets U, V, and W consists of mutually orthogonal elements;

each of U, V, and W includes at least six peripheral elements and at least three central elements;

the six peripheral elements of each set U, V, W are orthogonal to at least three peripheral elements of each of the other two sets; and

the received pilot signal is a peripheral element of U if the transmitting mobile station is near an edge of the cell, but is a central element of U if the transmitting mobile station is not near an edge of the cell.

10. The base station apparatus of claim 9 , further comprising a processor configured to precode a signal for transmission to a selected mobile station, wherein the precoding uses at least some of said information about the propagation channel.

11. Base station apparatus for a cellular network having a reuse factor of 3 for uplink pilot signals to be used for channel measurement such that each cell of respective reuse class A, B, or C may simultaneously have one or more edges adjacent to cells of the other two classes, said base station apparatus configured for a base station belonging to a reuse class A, and comprising:

a processor configured to classify each mobile station currently within a cell served by the base station as a center mobile, a peripheral mobile near a class B cell, or a peripheral mobile near a class C cell; and

a processor configured to allocate a set of mutually orthogonal pilot signals to the mobile stations such that each peripheral mobile station adjacent to a class B cell is allocated a pilot signal that is also orthogonal to some class B pilot signals, and each peripheral mobile station adjacent to a class C cell is allocated a pilot signal that is also orthogonal to some class C pilot signals; and

a transmitter, configured to transmit, to each said mobile station within the served cell, a signal designating at least one pilot signal that has been allocated to that mobile station.

12. A mobile station belonging to a cellular network in which at least three non-overlapping sets U, V, W of pilot signals are defined, comprising:

a receiver for receiving a signal from a base station designating a pilot signal of a set U, which is one of said three sets U, V, W, to be selected for transmission;

a storage element for storing information about the pilot signals constituting sets U, V, and W;

a processor for providing the designated pilot signal to a transmitter using the stored information; and

a transmitter for transmitting the designated pilot signal to the base station for the base station to derive, using a processor, information therefrom that characterizes the propagation channel between the mobile station and the base station using knowledge of the pilot signals in the set U; wherein:

in a representation of the pilot signals as vectors, each of the sets U, V, and W consists of mutually orthogonal elements;

each of U, V, and W includes at least six peripheral elements and at least three central elements;

the six peripheral elements of each set U, V, W are orthogonal to at least three peripheral elements of each of the other two sets; and

the transmitted pilot signal is a peripheral element of U if the transmitting mobile station is near an edge of the cell, but is a central element of U if the transmitting mobile station is not near an edge of the cell.

13. The mobile station of claim 12 , wherein:

each of the sets U, V, and W consists of nine mutually orthogonal signal vectors, and each said vector has nine components; and

each of the sets U, V, and W is either: a set, of vectors, having the property that all vector components are of the form e 2nπi/3 , wherein n=0, 1, or 2; or a set, of vectors, derivable from a set having said property by applying a common scale factor, phase shift, or unitary rotation to all vectors in the set having said property.

14. The mobile station of claim 12 , wherein:

at least three of the elements of V form an orthogonal basis with at least six of the elements of W; and

at least three of the elements of W form an orthogonal basis with at least six of the elements of V.

Assignments (10)