Optimum interleaver design for a communication system

1. A method for determining interleaver parameters for a multiple input multiple output (MIMO) communication system, the method comprising:

determining, at one or more processor devices, a maximum average distance for a plurality of adjacent spatial streams for a plurality of system configurations, wherein

the plurality of system configurations correspond to one or more of i) a plurality of different modulation and coding schemes (MCSs), ii) a plurality of different numbers of data tones, and/or iii) a plurality of different channel bandwidths, and

determining the maximum average distance for the plurality of adjacent spatial streams comprises calculating an average distance for multiple spatial streams for each of a plurality of interleaver parameter sets, wherein the average distance for multiple adjacent spatial streams for each of the plurality of interleaver parameter sets is calculated according to either

x

i

i

ss

→

z

k

i

ss

⁢

⁢

x

i

i

ss

+

1

→

z

m

i

ss

+

1

⁢

⁢

D

⁢

⁢

1

=

1

A

⁢

∑

i

ss

⁢

⁢

∑

k

⁢

⁢



k

-

m

⁢

⁢

1



(

i

)

wherein

D1 is the average distance for two adjacent spatial streams for a particular interleaver parameter set,

i is a data tone index before a permutation,

k is the data tone index after the permutation for an i ss -th spatial stream,

m1 is the data tone index after the permutation for an i ss +1-th spatial stream,

i ss is a spatial stream index, and

A is a normalizing factor, or

x

i

i

ss

→

z

k

i

ss

⁢

⁢

x

i

i

ss

+

j

→

z

m

i

ss

+

j

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0

<

j

≤

J

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⁢

D

⁢

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2

=

1

A

⁢

∑

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=

1

J

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∑

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ss

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⁢

∑

k

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

k

-

m

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2



(

ii

)

wherein

D2 is the average distance for J adjacent spatial streams for the particular interleaver parameter set, and

m2 is the data tone index after the permutation for an i ss +j-th spatial stream; and

determining, at one or more processor devices, an interleaver parameter set for the plurality of system configurations based on the determined maximum average distance.

2. The method of claim 1 , wherein determining the interleaver parameter set for the plurality of system configurations based on the determined maximum average distance comprises:

using packet error rate (PER) performance for the interleaver parameter set corresponding to the determined maximum average distance for each of the plurality of system configurations as a PER performance reference;

using packet error rate (PER) performance in each of the plurality of system configurations to compare the plurality of interleaver parameter sets; and

selecting the interleaver parameter set based on

i) the PER performance reference, and

ii) the PER performance in the plurality of system configurations.

3. The method of claim 1 , wherein:

determining the interleaver parameter set for the plurality of system configurations based on the determined maximum average distance comprises:

determining a frequency rotation parameter N ROT based on the determined maximum average distance, and

determining a set of spatial stream constants [n 0 , n 1 , . . . , n k ], where n 0 -n k are integers corresponding to spatial streams i ss =0 through i ss =k, respectively, based on the determined maximum average distance,

wherein

k is a number of spatial streams greater than 1; and

an offset frequency rotation is characterized by N ROT ×N BPSCS ×n i ss ,

wherein N BPSCS is a number of bits per subcarrier.

4. The method of claim 3 , wherein k is greater than 4.

5. A tangible, non-transitory computer readable medium having stored thereon machine executable instructions that, when executed by one or more processors, cause the one or more processors to determine interleaver parameters for a multiple input multiple output (MIMO) communication system by:

determining a maximum average distance for a plurality of adjacent spatial streams for a plurality of system configurations, wherein

the plurality of system configurations correspond to one or more of i) a plurality of different modulation and coding schemes (MCSs), ii) a plurality of different numbers of data tones, and/or iii) a plurality of different channel bandwidths, and

determining the maximum average distance for the plurality of adjacent spatial streams comprises calculating an average distance for multiple spatial streams for each of a plurality of interleaver parameter sets, wherein the average distance for multiple adjacent spatial streams for each of the plurality of interleaver parameter sets is calculated according to either

x

i

i

ss

→

z

k

i

ss

⁢

⁢

x

i

i

ss

+

1

→

z

m

i

ss

+

1

⁢

⁢

D

⁢

⁢

1

=

1

A

⁢

∑

i

ss

⁢

⁢

∑

k

⁢

⁢



k

-

m

⁢

⁢

1



(

i

)

wherein

D1 is the average distance for two adjacent spatial streams for a particular interleaver parameter set,

i is a data tone index before a permutation,

k is the data tone index after the permutation for an i ss -th spatial stream,

m1 is the data tone index after the permutation for an i ss +1-th spatial stream,

i ss is a spatial stream index, and

A is a normalizing factor, or

x

i

i

ss

→

z

k

i

ss

⁢

⁢

x

i

i

ss

+

j

→

z

m

i

ss

+

j

⁢

⁢

0

<

j

≤

J

⁢

⁢

D

⁢

⁢

2

=

1

A

⁢

∑

j

=

1

J

⁢

⁢

∑

i

ss

⁢

⁢

∑

k

⁢

⁢



k

-

m

⁢

⁢

2



(

ii

)

wherein

D2 is the average distance for J adjacent spatial streams for the particular interleaver parameter set, and

m2 is the data tone index after the permutation for an i ss +j-th spatial stream; and

determining an interleaver parameter set for the plurality of system configurations based on the determined maximum average distance.

6. The computer readable medium of claim 5 , wherein determining the interleaver parameter set for the plurality of system configurations based on the determined maximum average distance comprises:

using packet error rate (PER) performance for the interleaver parameter set corresponding to the determined maximum average distance for each of the plurality of system configurations as a PER performance reference,

using packet error rate (PER) performance in each of the plurality of system configurations to compare the plurality of interleaver parameter sets, and

selecting the interleaver parameter set based on

i) the PER performance reference, and

ii) the PER performance in the plurality of system configurations.

7. The computer readable medium of claim 5 , wherein determining the interleaver parameter set for the plurality of system configurations based on the determined maximum average distance comprises:

determining a frequency rotation parameter N ROT based on the determined maximum average distance;

determining a set of spatial stream constants [n 0 , n 1 , . . . , n k ], where n 0 -n k are integers corresponding to spatial streams i ss =0 through i ss =k, respectively, based on the determined maximum average distance,

wherein

k is a number of spatial streams greater than 1; and

an offset frequency rotation is characterized by N ROT ×N BPSCS ×n i ss ,

wherein N BPSCS is a number of bits per subcarrier.

8. The computer readable medium of claim 7 , wherein k is greater than 4.