Code division multiple access wireless system with closed loop mode using ninety degree phase rotation and beamformer verification
View Patent ↗A wireless communication system ( 10 ). The system comprises a user station ( 12 ). The user station comprises despreading circuitry ( 22 ) for receiving and despreading a plurality of slots received from at least a first transmit antenna (A 12 1 ) and a second transmit antenna (A 12 2 ) at a transmitting station ( 14 ). Each of the plurality of slots comprises a first channel (DPCH) comprising a first set of pilot symbols and a second channel (PCCPCH) comprising a second set of pilot symbols. The user station further comprises circuitry ( 50 ) for measuring a first channel measurement (α 1,n ) for each given slot in the plurality of slots from the first transmit antenna and in response to the first set of pilot symbols in the given slot. The user station further comprises circuitry ( 50 ) for measuring a second channel measurement (α 2,n ) for each given slot in the plurality of slots from the second transmit antenna and in response to the first set of pilot symbols in the given slot. The user station further comprises circuitry ( 52 ) for measuring a phase difference value (φ 2 (n)) for each given slot in the plurality of slots in response to the first channel measurement and the second channel measurement for the given slot and in response to a ninety degree rotation of the given slot relative to a slot which was received by the despreading circuitry immediately preceding the given slot.
1. A method of transmitting information, comprising the steps of:
receiving an information signal;
receiving at least one coefficient from a remote communication system;
averaging at least one coefficient over a plurality of slots, wherein the at least one coefficient is phase rotated by 90 degrees in each successive slot;
producing a plurality of weighted information signals from the at least one coefficient and the information signal; and
transmitting the plurality of weighted information signals from respective antennas.
2. A method as in claim 1 , comprising the steps of:
encoding the information signal;
interleaving the information signal;
symbol mapping the information signal; and
modulating the information signal.
3. A method as in claim 1 , wherein the step of producing a plurality of weighted information signals comprises the steps of:
multiplying the information signal by a first coefficient, thereby producing a first weighted information signal; and
multiplying the information signal by a second coefficient, thereby producing a second weighted information signal.
4. A method as in claim 3 , comprising the steps of:
transmitting the first weighted information signal from a first antenna; and
transmitting the second weighted information signal from a second antenna.
5. A method as in claim 1 , wherein the respective coefficients correspond respectively to previously transmitted weighted information signals.
6. A method as in claim 1 , comprising the steps of:
transmitting a first set of pilot symbols over a common pilot channel; and
transmitting a second set of pilot symbols and the weighted information signals over a dedicated physical channel (DPCH).
7. A method as in claim 1 , wherein the averaging step produces an average coefficient
ω
2
,
T
(
n
)
=
1
2
(
ⅇ
j
ϕ
2
(
n
)
+
ⅇ
j
ϕ
2
(
n
-
1
)
)
over time slots n and n−1.
8. A method as in claim 7 , wherein φ 2 (n)∈{0,π}, and wherein φ 2 (n−1)∈{π/2,−π/2}.
9. A method as in claim 7 , comprising the step of producing a normalized coefficient.
ω
1
,
T
(
n
)
=
1
2
.
10. A method as in claim 9 , wherein the step of producing a plurality of weighted information signals comprises multiplying the information signal by ω 1,T (n) and by ω 2,T (n).
11. A method of producing a coefficient in an electronic apparatus, comprising the steps of:
receiving in said electronic apparatus a first coefficient corresponding to an even time slot;
determining a phase angle is 0 when the first coefficient is 0;
determining the phase angle is π when the first coefficient is 1;
receiving in said electronic apparatus a second coefficient corresponding to an odd time slot;
determining the phase angle is π/2 when the second coefficient is 0; and
determining the phase angle is −π/2 when the second coefficient is 1.
12. A method as in claim 11 , wherein the first and second coefficients are received from a remote wireless transmitter.
13. A method as in claim 11 , comprising the step of averaging the first and second coefficients, wherein the second coefficient is phase rotated by 90 degrees with respect to the first coefficient.
14. A method as in claim 13 , comprising the step of producing a third coefficient
ω
2
,
T
(
n
)
=
1
2
(
ⅇ
j
ϕ
2
(
n
)
+
ⅇ
j
ϕ
2
(
n
-
1
)
)
in response to the step of averaging, wherein n and n−1 are indices of sequential time slots.
15. A method as in claim 14 , comprising the step of producing a fourth coefficient.
ω
1
,
T
(
n
)
=
1
2
.
16. A method as in claim 15 , comprising the steps of:
multiplying an information signal by the third coefficient, thereby producing a first weighted information signal; and
multiplying the information signal by the fourth coefficient, thereby producing a second weighted information signal.
17. A method of producing a coefficient, comprising the steps of:
receiving a first coefficient corresponding to an even time slot;
determining a phase angle is 0 whe the first coefficient is 0;
determining the phase angle is π when the first coefficient is 1;
receiving a second coefficient corresponding to an odd time slot;
determining the phase angle is π/2 when the second coefficient is 0;
determining the phase angle is −π/2 when the second coefficient is 1;
averaging the first and second coefficients, wherein the second coefficient is phase rotated by 90 degrees with respect to the first coefficient;
producing a third coefficient
ω
2
,
T
(
n
)
=
1
2
(
ⅇ
j
ϕ
2
(
n
)
+
ⅇ
j
ϕ
2
(
n
-
1
)
)
in response to the step of averaging, wherein n and n−1 are indices of sequential time slots;
producing a fourth coefficient;
ω
1
,
T
(
n
)
=
1
2
;
multiplying an information signal by the third coeficient, thereby producing a first weighted information signal;
multiplying the intormation signal by the fourth coefficient, thereby producing a second weigthed information signal; and
transmiting the first weighted information signal from a first antenna; and
transmitting the second weighted information signal front a second antenna.
18. A method of calculating a coefficient, comprising:
receiving at least one coefficient from a remote communication system;
averaging at least one coefficient over a plurality of slots, wherein the at least one coefficient is phase rotated by 90 degrees in each successive slot; and
producing a plurality of weighted information signals from the at least one coefficient and an information signal.
19. A method as in claim 18 , wherein the step of producing a plurality of weighted information signals comprises the steps of:
multiplying the information signal by a first coefficient, thereby producing a first weighted information signal; and
multiplying the information signal by a second coefficient, thereby producing a second weighted information signal.
20. A method as in claim 18 , wherein the respective coefficients correspond respectively to previously transmitted weighted information signals.
21. A method as in claim 18 , wherein the averaging step produces an average coefficient
ω
2
,
T
(
n
)
=
1
2
(
ⅇ
j
ϕ
2
(
n
)
+
ⅇ
j
ϕ
2
(
n
-
1
)
)
over time slots n and n−1.
22. A method as in claim 21 , wherein φ 2 (n)∈{0,π}, and wherein φ 2 (n−1)∈{π/2,−π/2}.
23. A method as in claim 21 , comprising the step of producing a normalized coefficient
ω
1
,
T
(
n
)
=
1
2
.
24. A method as in claim 23 , wherein the step of producing a plurality of weighted information signals comprises multiplying the information signal by ω 1,T (n) and by ω 2,T (n).
25. A transmit circuit, comprising:
a feedback circuit coupled to receive at least one coefficient from a remote communication system, the feedback circuit producing an average of the at least one coefficient over a plurality of slots, wherein the at least one coefficient is phase rotated by 90 degrees in each successive slot;
a first multiplier circuit having a first input terminal coupled to receive an information signal and having a second input terminal coupled to receive the average of the at least one coefficient, the first multiplier circuit having an output terminal coupled to receive a first weighted information signal; and
a first transmit antenna coupled to the first multiplier circuit output terminal.
26. A transmit circuit as in claim 25 , comprising:
a channel encoder circuit having an input terminal coupled to receive said information signal and having an output terminal;
an interleaver circuit having an output terminal and having an input terminal coupled to the output terminal of the channel encoder circuit;
a symbol mapper circuit having an output terminal and having an input terminal coupled to the output terminal of interleaver circuit; and
a modulator circuit having an output terminal coupled to the first input terminal of the first multiplier circuit and having an input terminal coupled to the output terminal of symbol mapper circuit.
27. A transmit circuit as in claim 25 , comprising:
a second multiplier circuit having a first input terminal coupled to receive the information signal and having a second input terminal coupled to receive a normalized coefficient, the multiplier circuit having an output terminal coupled to receive a second weighted information signal; and
a second transmit antenna coupled to the second multiplier circuit output terminal.
28. A transmit circuit as in claim 27 , wherein the normalized coefficient is
ω
1
,
T
(
n
)
=
1
2
.
29. A transmit circuit as in claim 25 , wherein the at least one coefficient corresponds to a previously transmitted weighted information signal.
30. A transmit circuit as in claim 25 , wherein the average of the at least one coefficient is
ω
2
,
T
(
n
)
=
1
2
(
ⅇ
j
ϕ
2
(
n
)
+
ⅇ
j
ϕ
2
(
n
-
1
)
)
over time slots n and n−1.
31. A transmit circuit as in claim 30 , wherein φ 2 (n)∈{0,π}, and wherein φ 2 (n−1)∈{π/2,−π/2}.