1. A method for communications device operation, the method comprising:
estimating a communications channel between the communications device and a controller serving the communications device, thereby producing a channel estimate;
quantizing the channel estimate using a codebook, wherein the codebook comprises a plurality of first level codewords, and wherein each first level codeword has a plurality of subsidiary codewords, thereby producing a selected codeword; and
transmitting an index corresponding to the selected codeword from the codebook to the controller,
wherein quantizing the channel estimate using a codebook comprises:
selecting a first level codeword from the plurality of first level codewords that maximizes |HWi|, i\u03b51, . . . , # first level codewords, where H is a channel matrix, and Wi are codewords of codebook, and # first level codewords is the number of first level codewords in the plurality of first level codewords;
selecting a subsidiary codeword from the plurality of subsidiary codewords of the first level codeword that maximizes |HWi|, i\u03b51, . . . , # subsidiary codewords, where # subsidiary codewords is the number of subsidiary codewords of the first level codeword; and
selecting either the first level codeword or the subsidiary codeword based on which codeword maximizes |HWi|, i\u03b5the first codeword, the subsidiary codeword as the selected codeword.
2. The method of claim 1, wherein selecting either the first level codeword or the subsidiary codeword comprises selecting the first level codeword in response to determining that the first level codeword and the subsidiary codeword substantially equally maximizes |HWi|, i\u03b5the first codeword, the subsidiary codeword.
3. The method of claim 1, wherein selecting either the first level codeword or the subsidiary codeword comprises randomly selecting either the first level codeword or the subsidiary codeword in response to determining the first level codeword and the subsidiary codeword substantially equally maximizes |HWi|, i\u03b5the first codeword, the subsidiary codeword.
4. The method of claim 1, wherein the communications device comprises four transmit antennas, and wherein the codebook is expressible as:
W=D\xd7W1; . . . ;W64,
where D is the phase rotation diagonal matrix and given by
D
=
\u2147
j
\u2062
\u2062
\u03b8
1
0
\u2026
0
0
\u2147
j
\u2062
\u2062
\u03b8
2
\u22f1
\u22ee
\u22ee
\u22f1
\u22f1
0
0
\u2026
0
\u2147
j
\u2062
\u2062
\u03b8
64
,
where \u03b8i\u03b50,2\u03c0), i\u03b51, . . . , 64.
5. The method of claim 1, wherein the number of subsidiary codewords in each plurality of subsidiary codewords is equal.
6. A method for communications device operation, the method comprising:
estimating a communications channel between the communications device and a controller serving the communications device, thereby producing a channel estimate;
quantizing the channel estimate using a codebook, wherein the codebook comprises a plurality of first level codewords, and wherein each first level codeword has a plurality of subsidiary codewords, thereby producing a selected codeword; and
transmitting an index corresponding to the selected codeword from the codebook to the controller,
wherein the communications device comprises four transmit antennas,
wherein the codebook is expressible as: W=D\xd7W1; . . . ; W64,
where D is the phase rotation diagonal matrix and given by
D
=
\u2147
j
\u2062
\u2062
\u03b8
1
0
\u2026
0
0
\u2147
j
\u2062
\u2062
\u03b8
2
\u22f1
\u22ee
\u22ee
\u22f1
\u22f1
0
0
\u2026
0
\u2147
j
\u2062
\u2062
\u03b8
64
,
where \u03b8i\u03b50,2\u03c0), i\u03b51, . . . , 64, and
wherein a codeword in the codebook is expressible as:
W4i+j=UiKHzj, i\u03b50, . . . ,15, j\u03b51, . . . ,4,
where Z=z1, z2, z3, z4 and K=z1, k2, k3, k4 are two 4\xd74 unitary matrices, zj is the j-th column of Z, matrices Z and K do not have to be identical, C=c1, . . . , c16 is a 4\xd716 matrix, ci, i\u03b51, . . . , 16 is 4\xd71 vector, and Ui is a 4\xd74 unitary matrix denoted by Ui=ci, ui2, ui3, ui4.
7. The method of claim 6, wherein matrix C is specified as follows:
c1
0.5000
\u22120.5000
0.5000
\u22120.5000
c2
\u22120.5000
\u22120.5000
0.5000
0.5000
c3
\u22120.5000
0.5000
0.5000
\u22120.5000
c4
0.5000
\u22120.5000I
0.5000
\u22120.5000I
c5
\u22120.5000
\u22120.5000I
0.5000
0.5000I
c6
\u22120.5000
0.5000I
0.5000
\u22120.5000I
c7
0.5000
0.5000
0.5000
\u22120.5000
c8
0.5000
\u22120.5000I
\u22120.5000
\u22120.5000I
c9
0.5000
\u22120.5000
0.5000
0.5000
c10
0.5000
0.5000I
\u22120.5000
0.5000I
c11
0.5000
\u20020.3536 + 0.3536I
0.5000I
\u22120.3536 + 0.3536I
c12
0.5000
\u20020.3536 \u2212 0.3536I
\u22120.5000I
\u22120.3536 \u2212 0.3536I
c13
0.5000
\u22120.3536 \u2212 0.3536I
0.5000I
\u20020.3536 \u2212 0.3536I
c14
0.5000
\u22120.3536 + 0.3536I
\u22120.5000I
\u20020.3536 + 0.3536I
c15
0.5000
0.5000
0.5000
0.5000
c16
0.5000
0.5000I
0.5000
0.5000I
8. The method of claim 6, wherein matrices Z and K are specified as follows:
Z
=
K
=
–
0.5
–
0.5
0.5
\u2062
\u2062
j
–
0.5
\u2062
\u2062
j
0.5
\u2062
\u2062
j
0.5
\u2062
\u2062
j
–
0.5
0.5
0.5
\u2062
\u2062
j
–
0.5
\u2062
\u2062
j
–
0.5
–
0.5
0.5
–
0.5
–
0.5
\u2062
\u2062
j
–
0.5
\u2062
\u2062
j
.
9. The method of claim 6, wherein matrix U is specified as follows:
U
1
=
0.5
–
0.5
–
0.5
0.5
–
0.5
–
0.5
0.5
0.5
0.5
0.5
0.5
0.5
–
0.5
0.5
–
0.5
0.5
\u2062
U
2
=
–
0.5
–
0.5
0.5
0.5
–
0.5
0.5
0.5
–
0.5
0.5
0.5
0.5
0.5
0.5
–
0.5
0.5
–
0.5
U
3
=
–
0.5
0.5
0.5
–
0.5
0.5
0.5
–
0.5
–
0.5
0.5
0.5
0.5
0.5
–
0.5
0.5
–
0.5
0.5
U
4
=
0.5
–
0.5
–
0.5
0.5
–
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
0.5
\u2062
j
0.5
0.5
0.5
0.5
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
U
5
=
–
0.5
–
0.5
0.5
0.5
–
0.5
\u2062
j
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
0.5
0.5
0.5
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
U
6
=
–
0.5
0.5
0.5
–
0.5
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
–
0.5
\u2062
j
0.5
0.5
0.5
0.5
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
U
7
=
0.5
0.5
–
0.5
–
0.5
0.5
–
0.5
–
0.5
\u2062
j
0.5
\u2062
j
0.5
0.5
0.5
0.5
0.5
–
0.5
0.5
\u2062
j
–
0.5
\u2062
j
U
8
=
0.5
0.5
–
0.5
–
0.5
0.5
\u2062
j
–
0.5
\u2062
j
–
0.5
0.5
0.5
0.5
0.5
0.5
0.5
\u2062
j
–
0.5
\u2062
j
0.5
–
0.5
U
9
=
0.5
0.5
0.5
0.5
0.5
–
0.5
\u2062
j
–
0.5
0.5
\u2062
j
0.5
–
0.5
0.5
–
0.5
–
0.5
–
0.5
\u2062
j
0.5
0.5
\u2062
j
U
10
=
0.5
0.5
0.5
0.5
–
0.5
\u2062
j
–
0.5
0.5
\u2062
j
0.5
–
0.5
0.5
–
0.5
0.5
–
0.5
\u2062
j
0.5
0.5
\u2062
j
–
0.5
U
11
=
0.5
0.5
0.5
0.5
–
0.5
0.5
\u2062
j
0.5
–
0.5
\u2062
j
0.5
–
0.5
0.5
–
0.5
0.5
0.5
\u2062
j
–
0.5
–
0.5
\u2062
j
U
12
=
0.5
0.5
0.5
0.5
0.5
\u2062
j
0.5
–
0.5
\u2062
j
–
0.5
–
0.5
0.5
–
0.5
0.5
0.5
\u2062
j
–
0.5
–
0.5
\u2062
j
0.5
U
13
=
0.5
0.5
0.5
0.5
1
8
+
1
8
\u2062
j
1
8
–
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
–
1
8
+
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
1
8
–
1
8
\u2062
j
1
8
+
1
8
\u2062
j
U
14
=
0.5
0.5
0.5
0.5
1
8
–
1
8
\u2062
j
1
8
\u2062
–
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
1
8
\u2062
–
1
8
\u2062
j
1
8
–
1
8
\u2062
j
1
8
+
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
U
15
=
0.5
0.5
0.5
0.5
–
1
8
–
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
1
8
+
1
8
\u2062
j
1
8
–
1
8
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
1
8
–
1
8
\u2062
j
1
8
+
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
U
16
=
0.5
0.5
0.5
0.5
–
1
8
+
1
8
\u2062
j
1
8
+
1
8
\u2062
j
1
8
–
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
–
0.5
\u2062
j
0.5
\u2062
j
1
8
+
1
8
\u2062
j
–
1
8
+
1
8
\u2062
j
–
1
8
–
1
8
\u2062
j
1
8
–
1
8
\u2062
j
.
10. The method of claim 6, wherein the codewords W1, . . . , W64 of the codebook W with four place precision are expressible as:
W1
0.5000
\u22120.5000
0.5000
\u22120.5000
W2
0.2570 + 0.1701i
\u22120.6097 \u2212 0.1826i\u2002
0.2570 \u2212 0.1701i
\u22120.6097 + 0.1826i\u2002
W3
0.3527 \u2212 0.4396i
0.4271i
\u22120.3527 \u2212 0.4396i\u2009
\u2003\u2003\u20090 + 0.4271i
W4
\u22120.1701 + 0.2570i\u2009
\u22120.1826 \u2212 0.6097i\u2009
0.1701 + 0.2570i
0.1826 \u2212 0.6097i
W5
\u22120.5000
\u22120.5000
0.5000
0.5000
W6
\u22120.6097 \u2212 0.1826i\u2002
\u22120.2570 \u2212 0.1701i\u2002
0.2570 \u2212 0.1701i
0.6097 \u2212 0.1826i
W7
\u2003\u2003\u20090 + 0.4271i
\u22120.3527 + 0.4396i\u2002
\u22120.3527 \u2212 0.4396i\u2002
\u22120.4271i
W8
\u22120.1826 \u2212 0.6097i\u2002
0.1701 \u2212 0.2570i
0.1701 + 0.2570i
\u22120.1826 + 0.6097i\u2002
W9
\u22120.5000
0.5000
0.5000
\u22120.5000
W10
\u22120.2570 \u2212 0.1701i\u2002
0.6097 + 0.1826i
0.2570 \u2212 0.1701i
\u22120.6097 + 0.1826i\u2002
W11
\u22120.3527 + 0.4396i\u2002
0 \u2212 0.4271i
\u22120.3527 \u2212 0.4396i\u2002
0.4271i
W12
0.1701 \u2212 0.2570i
0.1826 + 0.6097i
0.1701 + 0.2570i
0.1826 \u2212 0.6097i
W13
0.5000
\u22120.5000i
0.5000
\u22120.5000i
W14
0.2570 + 0.1701i
0.1826 \u2212 0.6097i
0.2570 \u2212 0.1701i
\u22120.1826 \u2212 0.6097i\u2002
W15
0.3527 \u2212 0.4396i
\u22120.4271
\u22120.3527 \u2212 0.4396i\u2002
\u22120.4271
W16
\u22120.1701 + 0.2570i\u2002
0.6097 \u2212 0.1826i
0.1701 + 0.2570i
0.6097 + 0.1826i
W17
\u22120.5000
\u22120.5000i
0.5000
0.5000i
W18
\u22120.6097 \u2212 0.1826i\u2002
0.1701 \u2212 0.2570i
0.2570 \u2212 0.1701i
0.1826 \u2212 0.6097i
W19
0.4271i
\u22120.4396 \u2212 0.3527i\u2002
\u22120.3527 \u2212 0.4396i\u2002
0.4271
W20
\u22120.1826 \u2212 0.6097i\u2002
0.2570 + 0.1701i
0.1701 + 0.2570i
\u22120.6097 \u2212 0.1826i\u2002
W21
\u22120.5000
0.5000i
0.5000
\u22120.5000i
W22
\u22120.2570 \u2212 0.1701i\u2002
\u22120.1826 + 0.6097i\u2002
0.2570 \u2212 0.1701i
\u22120.1826 \u2212 0.6097i\u2002
W23
\u22120.3527 + 0.4396i\u2002
0.4271
\u22120.3527 \u2212 0.4396i\u2002
\u22120.4271
W24
0.1701 \u2212 0.2570i
\u22120.6097 + 0.1826i\u2002
0.1701 + 0.2570i
0.6097 + 0.1826i
W25
0.5000
0.5000
0.5000
0.5000
W26
0.6097 + 0.1826i
0.2570 \u2212 0.1826i
0.2570 \u2212 0.1701i
0.6097 + 0.1701i
W27
\u22120.4271i
0.1826 \u2212 0.2570i
\u22120.3527 \u2212 0.4396i\u2002
0.1701 \u2212 0.6097i
W28
0.1826 + 0.6097i
0.4396i
0.1701 + 0.2570i
\u22120.3527 + 0.4271i\u2002
W29
0.5000
0.5000i
0.5000
0.5000i
W30
0.6097 + 0.1826i
\u22120.1701 + 0.6097i\u2002
0.2570 \u2212 0.1701i
0.1826 + 0.2570i
W31
\u22120.4271i
0.6097 + 0.1701i
\u22120.3527 \u2212 0.4396i\u2002
0.2570 + 0.1826i
W32
0.1826 + 0.6097i
\u22120.4271 \u2212 0.3527i\u2002
0.1701 + 0.2570i
\u22120.4396
W33
0.5000
0.5000
0.5000
\u22120.5000
W34
0.2570 \u2212 0.1701i
0.4396
0.6097 \u2212 0.1826i
\u22120.4271 \u2212 0.3527i\u2002
W35
\u22120.3527 \u2212 0.4396i\u2002
0.1826 \u2212 0.2570i
\u22120.4271i
\u22120.1701 + 0.6097i\u2002
W36
0.1701 + 0.2570i
0.1826 + 0.2570i
\u22120.1826 + 0.6097i\u2002
0.1701 \u2212 0.6097i
W37
0.5000
\u22120.5000i
\u22120.5000
\u22120.5000i
W38
0.2570 \u2212 0.1701i
\u22120.4396i
\u22120.6097 + 0.1826i\u2002
0.3527 \u2212 0.4271i
W39
\u22120.3527 \u2212 0.4396i\u2002
\u22120.2570 \u2212 0.1826i\u2002
0.4271i
\u22120.6097 \u2212 0.1701i\u2002
W40
0.1701 + 0.2570i
0.2570 \u2212 0.1826i
0.1826 \u2212 0.6097i
0.6097 + 0.1701i
W41
0.5000
\u22120.5000
0.5000
0.5000
W42
0.2570 \u2212 0.1701i
\u22120.4396
0.6097 \u2212 0.1826i
0.4271 + 0.3527i
W43
\u22120.3527 \u2212 0.4396i\u2002
\u22120.1826 + 0.2570i\u2002
\u22120.4271i
0.1701 \u2212 0.6097i
W44
0.1701 + 0.2570i
\u22120.1826 \u2212 0.2570i\u2002
\u22120.1826 + 0.6097i\u2002
\u22120.1701 + 0.6097i\u2002
W45
0.5000
0.5000i
\u22120.5000
0.5000i
W46
0.2570 \u2212 0.1701i
0.4396i
\u22120.6097 + 0.1826i\u2002
\u22120.3527 + 0.4271i\u2002
W47
\u22120.3527 \u2212 0.4396i\u2002
0.2570 + 0.1826i
0.4271i
0.6097 + 0.1701i
W48
0.1701 + 0.2570i
\u22120.2570 + 0.1826i\u2002
0.1826 \u2212 0.6097i
\u22120.6097 \u2212 0.1701i\u2002
W49
0.5000
0.3536 + 0.3536i
0.5000i
\u22120.3536 + 0.3536i\u2002
W50
0.2570 \u2212 0.1701i
0.3108 + 0.3108i
0.1826 + 0.6097i
\u22120.5514 + 0.0526i\u2002
W51
\u22120.3527 \u2212 0.4396i\u2002
0.3108 \u2212 0.0526i
0.4271
0.3108 + 0.5514i
W52
0.1701 + 0.2570i
\u22120.0526 + 0.3108i\u2002
\u22120.6097 \u2212 0.1826i\u2002
\u22120.3108 \u2212 0.5514i\u2002
W53
0.5000
0.3536 \u2212 0.3536i
\u22120.5000i
\u22120.3536 \u2212 0.3536i\u2002
W54
0.2570 \u2212 0.1701i
0.3108 \u2212 0.3108i
\u22120.1826 \u2212 0.6097i\u2002
\u22120.0526 \u2212 0.5514i\u2002
W55
\u22120.3527 \u2212 0.4396i\u2002
\u22120.0526 \u2212 0.3108i\u2002
\u22120.4271
\u22120.5514 + 0.3108i\u2002
W56
0.1701 + 0.2570i
0.3108 + 0.0526i
0.6097 + 0.1826i
0.5514 \u2212 0.3108i
W57
0.5000
\u22120.3536 \u2212 0.3536i\u2002
0.5000i
0.3536 \u2212 0.3536i
W58
0.2570 \u2212 0.1701i
\u22120.3108 \u2212 0.3108i\u2002
0.1826 + 0.6097i
0.5514 \u2212 0.0526i
W59
\u22120.3527 \u2212 0.4396i\u2002
\u22120.3108 + 0.0526i\u2002
0.4271
\u22120.3108 \u2212 0.5514i\u2002
W60
0.1701 + 0.2570i
0.0526 \u2212 0.3108i
\u22120.6097 \u2212 0.1826i\u2002
0.3108 + 0.5514i
W61
0.5000
\u22120.3536 + 0.3536i\u2002
\u22120.5000i
0.3536 + 0.3536i
W62
0.2570 \u2212 0.1701i
\u22120.3108 + 0.3108i\u2002
\u22120.1826 \u2212 0.6097i\u2002
0.0526 + 0.5514i
W63
\u22120.3527 \u2212 0.4396i\u2002
0.0526 + 0.3108i
\u22120.427i
0.5514 \u2212 0.3108i
W64
0.1701 + 0.2570i
\u22120.3108 \u2212 0.0526i\u2002
0.6097 + 0.1826i
\u22120.5514 + 0.3108i\u2002
11. A method for communications device operation, the method comprising:
estimating a communications channel between the communications device and a controller serving the communications device, thereby producing a channel estimate;
performing a first stage quantization of the channel estimate using a codebook, wherein the codebook comprises a plurality of first level codewords, wherein each first level codeword has a plurality of subsidiary codewords, and wherein the first stage quantization uses only the plurality of first level codewords, thereby producing a selected first level codeword;
transmitting a first index corresponding to the selected first level codeword from the codebook to the controller;
performing a second stage quantization of the channel estimate using the codebook, wherein the second stage quantization uses the entirety of the codebook, thereby producing a selected codeword; and
transmitting a second index corresponding to the selected codeword from the codebook to the controller,
wherein performing a first stage quantization of the channel estimate comprises, selecting a first level codeword from the plurality of first level codewords that maximizes |HWi|, i\u03b51, . . . , # first level codewords as the selected first level codeword, where H is a channel matrix, and Wi are codewords of codebook, and # first level codewords is the number of first level codewords in the plurality of first level codewords.
12. A method for communications device operation, the method comprising:
estimating a communications channel between the communications device and a controller serving the communications device, thereby producing a channel estimate;
performing a first stage quantization of the channel estimate using a codebook, wherein the codebook comprises a plurality of first level codewords, wherein each first level codeword has a plurality of subsidiary codewords, and wherein the first stage quantization uses only the plurality of first level codewords, thereby producing a selected first level codeword;
transmitting a first index corresponding to the selected first level codeword from the codebook to the controller;
performing a second stage quantization of the channel estimate using the codebook, wherein the second stage quantization uses the entirety of the codebook, thereby producing a selected codeword; and
transmitting a second index corresponding to the selected codeword from the codebook to the controller,
wherein performing a second stage quantization of the channel estimate comprises:
selecting a subsidiary codeword from the plurality of subsidiary codewords of the selected first level codeword that maximizes |HWi|, i\u03b51, . . . , # subsidiary codewords, where H is a channel matrix, and Wi are codewords of codebook, and # subsidiary codewords is the number of subsidiary codewords of the first level codeword; and
selecting either the selected first level codeword or the subsidiary codeword based on which codeword maximizes |HWi|, i\u03b5the first codeword, the subsidiary codeword as the selected codeword.
13. The method of claim 12, wherein selecting either the selected first level codeword or the subsidiary codeword comprises, selecting the selected first level codeword in response to determining that the first level codeword and the subsidiary codeword substantially equally maximizes |HWi|, i\u03b5the first codeword, the subsidiary codeword.
14. The method of claim 12, further comprising, normalizing the channel estimate prior to performing a first stage quantization of the channel estimate.
15. A method for controller operation, the method comprising:
receiving a first channel state information (CSI) from a communications device, wherein the first CSI comprises a first index to a first level codeword in a codebook, wherein the codebook comprises a plurality of first level codewords, wherein each first level codeword has a plurality of subsidiary codewords;
reconstructing a first channel estimate using the codebook and the first index;
adjusting transmission circuitry in the controller using the reconstructed first channel estimate; and
receiving a second CSI from a communications device, wherein the second CSI comprises a second index to a codeword in the codebook;
wherein in response to determining that the first index is different from the second index, the method further comprises:
reconstructing a second channel estimate using the codebook and the second index,
adjusting transmission circuitry in the controller using the reconstructed second channel estimate;
transmitting a first transmission to the communications device using the adjusted transmission circuitry, wherein transmitting the first transmission comprises:
in response to determining that the first index is not different from the second index, precoding the transmission with the reconstructed first channel estimate, thereby producing a first precoded transmission, and transmitting the first precoded transmission to the communications device; and
in response to determining that the first index is different from the second index, precoding the transmission with the reconstructed second channel estimate, thereby producing a second precoded transmission, and transmitting the second precoded transmission to the communications device.
16. The method of claim 15, further comprising, prior to receiving a second CSI, transmitting a second transmission to the communications device.
17. The method of claim 15, wherein the first CSI is encoded in a message from the communications device, and wherein receiving a first CSI comprises:
receiving the first CSI; and
decoding the first CSI to extract the first index.
18. A communications device comprising:
a processor; and
a computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
perform channel estimation on a communications channel between the communications device and a controller serving the communications device to produce a channel estimate;
quantize the channel estimate using a codebook to produce a selected codeword, wherein the codebook comprises a plurality of first level codewords and a plurality of subsidiary codewords, and wherein each first level codeword corresponds to a unique sub-set of the plurality of subsidiary codewords, wherein fewer than all of the plurality of subsidiary codewords are included in the unique sub-set of subsidiary codewords corresponding to the optimal first level codeword, and wherein none of the plurality of first level codewords are subsidiary codewords; and
transmit an index corresponding to the selected codeword from the codebook to the controller.
19. The communications device of claim 18, wherein the instructions to quantize the channel estimate include instructions to:
analyze the plurality of first level codewords to identify an optimal one of the plurality of first level codewords;
analyze each subsidiary codeword in the unique sub-set of subsidiary codewords that corresponds to the optimal first level codeword to identify an optimal subsidiary codeword, wherein subsidiary codewords in the plurality of subsidiary codewords that are not included in the unique sub-set of subsidiary codewords corresponding to the optimal first level codeword are not analyzed during said quantization; and
pursuant to said analysis, select one of the optimal first level codeword or the optimal subsidiary codeword as the selected codeword.
20. A communications device for performing quantization using a codebook that includes a plurality of first level codewords and a plurality of subsidiary codewords, the communications device comprising:
a processor; and
a computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
estimate a communications channel between the communications device and a controller serving the communications device to produce a channel estimate;
perform a first stage quantization of the channel estimate to identify an optimal one of the plurality of first level codewords;
transmit a first indication that identifies the optimal first level codeword;
subsequent to transmitting the first indication, perform a second stage quantization of the channel estimate to identify an optimal codeword; and
transmit a second indication that identifies the optimal codeword,
wherein each of the plurality of first level codewords corresponds to a unique sub-set of the plurality of subsidiary codewords, and
wherein the instructions to perform the second stage quantization include instructions to analyze each subsidiary codeword in the unique sub-set of subsidiary codewords corresponding to the optimal first level codeword without analyzing ones of the plurality of subsidiary codewords that are not in the unique sub-set of subsidiary codewords corresponding to the optimal first level codeword.
21. The communications device of claim 20, wherein the instructions to perform the first stage quantization include instructions to analyze each of the plurality of first level codewords without analyzing any of the subsidiary codewords.
22. The communications device of claim 21, wherein the instructions to perform the second stage quantization include instructions to analyze at least some of the plurality of subsidiary codewords.
23. The communications device of claim 20, wherein fewer than all of the plurality of subsidiary codewords are included in the unique sub-set of subsidiary codewords corresponding to the optimal first level codeword, and wherein none of the first level codewords are subsidiary codewords.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A p-type semiconductor structure comprising:
a semiconductor substrate;
an interfacial layer comprised of SiO2 located on said semiconductor substrate, and having a thickness ranging from about 0.1 nm to about 5 nm, and having interface states below 1\xd71011 chargescm2;
a high k dielectric comprised of a Hf based material located on said interfacial layer; and a TiC metal gate located on said high k dielectric, the TiC metal gate having a workfunction between 4.75 and 5.3 eV, wherein a sidewall of the TiC metal gate is aligned to a sidewall of the high-k dielectric and is aligned to a sidewall of the interfacial layer.
2. The semiconductor structure of claim 1 wherein said semiconductor substrate comprises Si, Ge, SiGe, SiC, SiGeC, Ga, GaAs, InAs, InP, other IIIV or IIIVI compound semiconductors, organic semiconductors or layered semiconductors.
3. The semiconductor structure of claim 1 wherein said interfacial layer has a Si content from about 1 to about 80 atomic percent.
4. The semiconductor structure of claim 1 wherein said interfacial layer has a Si content that is graded.
5. The semiconductor structure of claim 1 wherein said high k dielectric has a dielectric constant that is greater than 4.0 and a thickness from about 0.5 to about 10 nm.
6. The semiconductor structure of claim 1 wherein said high k dielectric comprises an oxide, nitride, oxynitride, silicate or mixtures thereof.
7. The semiconductor structure of claim 1 wherein said high k dielectric comprises HfO2, Hf silicate or Hf oxynitride.
8. The semiconductor structure of claim 1 wherein said interfacial layer, said high k dielectric and said TiC gate metal are patterned into a gate region.
9. The semiconductor structure of claim 1 further comprising a Si-containing conductive material atop said TiC metal gate.
10. A p-type semiconductor structure comprising:
a semiconductor substrate;
an interfacial layer comprised of SiO2 located on said semiconductor substrate, and having a thickness ranging from about 0.1 nm to about 5 nm, and having interface states below 1\xd71011 chargescm2;
a high k dielectric comprised located on said interfacial layer; and
a TiC metal gate located on said high k dielectric, the TiC metal gate having a workfunction between 4.75 and 5.3 eV, wherein said p-type semiconductor structure has an inversion layer thickness of about 14 \u212b or less.
11. The p-type semiconductor structure of claim 10 wherein said semiconductor substrate comprises Si, Ge, SiGe, SiC, SiGeC, Ga, GaAs, InAs, InP, other IIIV or IIIVI compound semiconductors, organic semiconductors or layered semiconductors.
12. The p-type semiconductor structure of claim 10 wherein said interfacial layer has a Si content from about 1 to about 80 atomic percent.
13. The p-type semiconductor structure of claim 10 wherein said interfacial layer has a Si content that is graded.
14. The p-type semiconductor structure of claim 10 wherein said high k dielectric has a dielectric constant that is greater than 4.0 and a thickness from about 0.5 to about 10 nm.
15. The p-type semiconductor structure of claim 10 wherein said high k dielectric comprises an oxide, nitride, oxynitride, silicate or mixtures thereof.
16. The p-type semiconductor structure of claim 10 wherein said high k dielectric comprises HfO2, Hf silicate or Hf oxynitride.
17. The p-type semiconductor structure of claim 10 wherein said interfacial layer, said high k dielectric and said TiC gate metal are patterned into a gate region.
18. The p-type semiconductor structure of claim 10 further comprising a Si-containing conductive material atop said TiC metal gate.