Signal transmission multiple antenna method and device
View Patent ↗The invention lies within the field of wireless communications systems with several transmitting antennas, corresponding to MIMO (Multiple Input Multiple Output) systems or to MISO (Multiple Input Single Output) systems. According to the invention, the symbols to be transmitted are pre-encoded with a particular linear pre-encoding matrix then coded according to space-time block coding so as to benefit to the full from temporal and spatial diversities allowing at reception for particularly easy and efficient linear decoding.
1. Method of transmitting a signal composed of a plurality of symbols from n e transmitting antennas, n e being a whole number greater than or equal to 2, the method comprising the steps of:
performing a linear pre-encoding operation on the symbols to be transmitted so as to generate, for each burst of m consecutive symbols to be transmitted, m linear combinations of symbols, m being a whole number greater than or equal to n e , the linear pre-encoding operation consisting in applying to each vector of m consecutive symbols to be transmitted a complex orthonormal pre-encoding matrix of dimension m×m so as to create the m linear combinations of symbols, and
for each burst of m consecutive symbols to be transmitted, coding the m linear combinations according to a space-time coding so as to transmit one after the other blocks of q coded linear combinations, q being a whole number smaller than or equal to m, each block of q coded linear combinations being transmitted from q′ transmitting antennas, q′ being a whole number greater than or equal to q, each of the coded linear combinations of the block of q coded linear combinations being transmitted during q″ consecutive temporal transmitting intervals specific to the block from one of the n e transmitting antennas, q″ being a whole number greater than or equal to q,
wherein the pre-encoding matrix is the Kronecker product of a Hadamard matrix of order
m
k
by a matrix of the Special Unitary group SU(k), k being a whole number greater than or equal to 2.
2. Method according to claim 1 , wherein q, q′ and q″ are equal to 2.
3. Method according to claim 2 , wherein n e is equal to 2.
4. Method according to claim 1 , wherein the number n e of transmitting antennas is equal to m, each coded linear combination being transmitted from a transmitting antenna specific to it.
5. Method according to any one of claims 1 to 4 , further comprising the step of, prior to the step of coding the m linear combinations, interleaving the linear combinations to modify the temporal order of the latter.
6. Method according to claim 5 , wherein the interleaving step is performed with the aid of an interleaving matrix of dimension m′×m′, m′ being greater than or equal to m.
7. Method according to claim 1 , wherein the matrix of the Special Unitary group SU(2) is of type
[
SU
(
2
)
]
=
[
a
b
-
b
*
a
*
]
=
[
ⅇ
ⅈ
θ
1
cos
η
ⅇ
ⅈ
θ
2
sin
η
-
ⅇ
-
ⅈ
θ
2
sin
η
ⅇ
-
ⅈ
θ
i
cos
η
]
with
η
=
Π
4
+
k
′
Π
2
,
θ
1
=
-
θ
2
+
Π
2
+
k
″
Π
and
θ
2
=
θ
1
-
π
2
,
k
′
and k″ being integers.
8. Method of receiving a signal comprised of a plurality of symbols transmitted from n e transmitting antennas, n e being greater than or equal to 2, the symbols being transmitted by:
performing a linear pre-encoding operation on the symbols to be transmitted so as to generate, for each burst of m consecutive symbols to be transmitted, m linear combinations of symbols, m being a whole number greater than or equal to ne, the linear pre-encoding operation consisting in applying to each vector of m consecutive symbols to be transmitted a complex orthonormal pre-encoding matrix of dimension m×m so as to create the m linear combinations of symbols, and
for each burst of m consecutive symbols to be transmitted, coding the m linear combinations according to a space-time coding so as to transmit one after the other blocks of q coded linear combinations, q being a whole number smaller than or equal to m, each block of q coded linear combinations being transmitted from q′ transmitting antennas, q′ being a whole number greater than or equal to q, each of the coded linear combinations of the block of q coded linear combinations being transmitted during q″ consecutive temporal transmitting intervals specific to the block from one of the n e transmitting antennas, q″ being a whole number greater than or equal to q,
the method of receiving comprising the steps of:
receiving the signal comprised of the plurality of symbols transmitted from the n e transmitting antennas with the aid of n r receiving antennas, n r being a whole number greater than or equal to 1, and
decoding the m coded linear combinations received on each of the n r receiving antennas by performing an inverse space-time coding operation and an inverse linear pre-encoding operation so as to retrieve, from the m coded linear combinations that were transmitted, the m transmitted symbols,
wherein the inverse linear pre-encoding operation consists in applying to the linear combinations derived from the inverse space-time coding operation a complex orthonormal inverse pre-encoding matrix, and
the m retrieved symbols corresponding to the result of the application of a global matrix with diagonal elements proportional to a sum of diagonal elements of a diagonal matrix, and with at least several non diagonal elements proportional to a difference between diagonal elements of the diagonal matrix, the other non diagonal elements being zero, the diagonal matrix corresponding to the transformation of the m linear combinations of symbols into the linear combinations derived from the inverse space-time coding operation.
9. Method of receiving a signal composed of a plurality of symbols transmitted from n e transmitting antennas, n e being greater than or equal to 2, the symbols being transmitted by:
performing a linear pre-encoding operation on the symbols to be transmitted so as to generate, for each burst of m consecutive symbols to be transmitted, m linear combinations of symbols, m being a whole number greater than or equal to n e , the linear pre-encoding operation consisting in applying to each vector of m consecutive symbols to be transmitted a complex orthonormal pre-encoding matrix of dimension m×m so as to create the m linear combinations of symbols,
for each burst of m consecutive symbols to be transmitted, coding the m linear combinations according to a space-time coding so as to transmit one after the other blocks of q coded linear combinations, q being a whole number smaller than or equal to m, each block of q coded linear combinations being transmitted from q′ transmitting antennas, q′ being a whole number greater than or equal to q, each of the coded linear combinations of the block of q coded linear combinations being transmitted during q″ consecutive temporal transmitting intervals specific to the block from one of the n e transmitting antennas, q″ being a whole number greater than or equal to q, and
prior to the step of coding the m linear combinations, interleaving the linear combinations to modify the temporal order of the latter,
the method of receiving comprising the steps of:
receiving the signal composed of the plurality of symbols transmitted from the n e transmitting antennas with the aid of n r receiving antennas, n r being a whole number greater than or equal to 1, and
decoding the m coded linear combinations received on each of the n r receiving antennas by performing an inverse space-time coding operation, an inverse interleaving operation and an inverse linear pre-encoding operation so as to retrieve, from the m coded linear combinations that were transmitted, the transmitted symbols,
wherein the inverse linear pre-encoding operation consists in applying to the linear combinations derived from the inverse space-time coding operation a complex orthonormal inverse pre-encoding matrix, and
the m retrieved symbols corresponding to the result of the application of a global matrix with diagonal elements proportional to a sum of diagonal elements of a diagonal matrix, and with non diagonal elements proportional to a difference between at least two diagonal elements of the diagonal matrix, the diagonal matrix corresponding to the transformation of the m linear combinations of symbols into the linear combinations derived from the inverse space-time coding operation and from the inverse interleaving operation.
10. Wireless communications system comprising:
means of transmitting a signal composed of a plurality of symbols from n e transmitting antennas, n e being a whole number greater than or equal to 2,
wherein the means of transmitting includes:
means for performing a linear pre-encoding operation on the symbols to be transmitted so as to generate, for each burst of m consecutive symbols to be transmitted, m linear combinations of symbols, m being a whole number greater than or equal to n e , the linear pre-encoding operation consisting in applying to each vector of m consecutive symbols to be transmitted a complex orthonormal pre-encoding matrix of dimension m×m so as to create the m linear combinations of symbols, and
means for, for each burst of m consecutive symbols to be transmitted, coding the m linear combinations according to a space-time coding so as to transmit one after the other blocks of q coded linear combinations, q being a whole number smaller than or equal to m, each block of q coded linear combinations being transmitted from q′ transmitting antennas, q′ being a whole number greater than or equal to q, each of the coded linear combinations of the block of q coded linear combinations being transmitted during q″ consecutive temporal transmitting intervals specific to the block from one of the n e transmitting antennas, q″ being a whole number greater than or equal to q, and
the pre-encoding matrix is the Kronecker product of a Hadamard matrix of order
m
k
by a matrix of the Special Unitary group SU(k), k being a whole number greater than or equal to 2.
11. Wireless communications system according to claim 10 , further comprising:
means for receiving the signal composed of the plurality of symbols transmitted from the n e transmitting antennas with the aid of n r receiving antennas, n r being a whole number greater than or equal to 1,
wherein the means for receiving includes means for decoding the m coded linear combinations received on each of the n r receiving antennas by performing an inverse space-time coding operation and an inverse linear pre-encoding operation so as to retrieve, from the m coded linear combinations that were transmitted, the m transmitted symbols.