INTERLEAVING IN A WIRELESS COMMUNICATION SYSTEM
The method and apparatus in accordance with the present invention receives bits, writes the bits row-by-row in a matrix, reads the bits column-by-column from the matrix, groups and rotates the bits read column-by-column from the matrix so as to evenly separate the bits in position, frequency, space over one symbol period.
1 . A method to interleave bits, comprising:
receiving bits;
interleaving adjacent received bits over frequency, position, and multiple streams to generate interleaved bits; and
transmitting the interleaved bits over multiple streams using multiple antennas.
2 . The method of claim 1 , wherein the received bits are interleaved across a single symbol period.
3 . The method of claim 1 , the transmitting step comprising transmitting the interleaved bits within a pre-determined symbol period.
4 . The method of claim 1 , the interleaving step further comprising:
writing said received bits row-by-row in a matrix;
reading said bits written row-by-row in said matrix column-by-column;
grouping a pre-determined number of said bits read column-by-column to form subsymbols;
grouping said subsymbols to form groups of subsymbols; and
rotating said groups of subsymbols to form rotated groups of subsymbols.
5 . The method of claim 4 , further comprising transmitting the rotated groups of subsymbols over multiple streams using multiple antennas.
6 . The method of claim 4 , wherein a size of said matrix (N′ CBPS ) is defined as:
N′ CBPS =N SS ×K×B;
wherein,
N SS is the number of streams;
K is the number of tones/stream and
B is the number of bits/tone.
7 . The method of claim 4 , further comprising the step of mapping adjacent received bits onto nonadjacent tones and non-adjacent streams using a first permutation.
8 . The method of claim 7 , further comprising mapping adjacent received bits alternately onto less and more significant bits of a constellation using a second permutation.
9 . The method of claim 8 , wherein said first permutation is defined as:
i
=
N
CBPS
′
r
(
k
mod
r
)
+
⌊
k
r
⌋
where
k
=
0
,
1
,
…
N
CBPS
′
-
1
;
and said second permutation is defined as:
j
=
s
⌊
i
s
⌋
+
(
i
+
N
CBPS
′
-
⌊
ri
N
CBPS
′
⌋
)
mod
s
where
i
=
0
,
1
…
N
CBPS
′
-
1
;
wherein,
r is the number of columns in the matrix;
k denotes the index of the bit before the first permutation;
i denotes the index after the first but before the second permutation;
j denotes the index after the second permutation; and
N′ CBPS is the number of coded bits per sub carrier.
10 . The method of claim 4 , wherein said pre-determined number of bits is a number of bits per tone.
11 . The method of claim 4 , wherein rotating said group of sub-symbols increases separation between adjacent bits.
12 . The method of claim 1 , wherein at least four tones and one stream separation is introduced between adjacent received bits and interleaved bits.
13 . The method of claim 1 , wherein successive bits are modulated onto alternate streams.
14 . A tangible computer-readable medium having stored thereon, computer-executable instructions that, if executed by a computing device, cause the computing device to perform a method to interleave bits, comprising:
receiving bits;
interleaving adjacent received bits over frequency, position, and multiple streams to generate interleaved bits; and
transmitting the interleaved bits over multiple streams using multiple antennas.
15 . The tangible computer-readable medium of claim 14 , wherein the received bits are interleaved across a single symbol period.
16 . The tangible computer-readable medium of claim 14 , further comprising instructions that, if executed by a computing device, cause the computing device to perform the step of mapping adjacent received bits onto nonadjacent tones and non-adjacent streams using a first permutation.
17 . The tangible computer-readable medium of claim 16 , further comprising instructions that, if executed by a computing device, cause the computing device to perform the step of mapping adjacent received bits alternately onto less and more significant bits of a constellation using a second permutation.
18 . A system to interleave and transmit data, comprising:
an interleaver configured to receive bits and interleave adjacent received bits over frequency, position, and multiple streams to generate interleaved bits; and
a transmitter configured to transmit the interleaved bits over multiple streams using multiple antennas.
19 . The system of claim 18 , wherein the received bits are interleaved across a single symbol period.
20 . The system of claim 18 , wherein the interleaver is configured to map adjacent received bits onto nonadjacent tones and non-adjacent streams using a first permutation and map adjacent received bits alternately onto less and more significant bits of a constellation using a second permutation.