Reference signal mapping

1. A method, performed by a wireless terminal, of mapping a set of reference signal samples to subcarriers within a bandwidth allocated for transmission over a channel, wherein each sample has an associated index value from a set of consecutive index values, and the set of reference signal samples are consecutively ordered by their index value, the method comprising:

determining a first subset of samples from the set of reference signal samples that have contiguous index values, wherein a first sample of the first subset of samples has a lowest index value in the set of consecutive index values;

determining a second subset of samples from the set of reference signal samples that have contiguous index values, wherein a last sample of the second subset of samples has a highest index value in the set of consecutive index values, wherein each index value of the second subset of samples is higher than each index value of the first subset of samples, and wherein each sample in the set is included in one of the first or second subsets of samples;

mapping the second subset of samples to a first subset of subcarriers of the bandwidth, including mapping a first sample of the second subset of samples having a lowest index value of the second subset of samples to a first subcarrier at a first end of the bandwidth; and

mapping the first subset of samples to a second subset of subcarriers of the bandwidth, including mapping a last sample of the first subset of samples having a highest index value of the first subset of samples to a last subcarrier at an opposite second end of the bandwidth.

2. The method of claim 1 , wherein:

the first subset of samples are contiguously mapped to the second subset of subcarriers; and

the second subset of samples are contiguously mapped to the first subset of subcarriers.

3. The method of claim 1 :

wherein the first subset of subcarriers spans over a first portion of the bandwidth;

wherein the second subset of subcarriers spans over a different second portion of the bandwidth;

wherein the method further comprises mapping a third subset of samples to a third subset of subcarriers of the bandwidth;

wherein the third subset of subcarriers span over a third portion of the bandwidth that is situated between the first and second portions of the bandwidth; and

wherein the first, second, and third portions of the bandwidth do not overlap.

4. The method of claim 3 , wherein:

the first and second subsets of samples are from a first reference signal sequence; and

the third subset of samples is from a second reference signal sequence.

5. The method of claim 1 , wherein the reference signal samples are one of Sounding Reference Signal (SRS) samples and Demodulation Reference Sequence (DMRS) samples.

6. The method of claim 1 , wherein the channel comprises a Physical Uplink Shared Channel (PUSCH) in a Long Term Evolution (LTE) network.

7. The method of claim 1 , wherein the first subcarrier at the first end of the bandwidth has a lowest frequency of the subcarriers within the bandwidth, and the last subcarrier at the opposite second end of the bandwidth has a highest frequency of the subcarriers within the bandwidth.

8. A wireless terminal operative to map a set of reference signal samples to subcarriers within a bandwidth allocated for transmission over a channel, wherein each sample has an associated index value from a set of consecutive index values, and the set of reference signal samples are consecutively ordered by their index value, the wireless terminal comprising

a subcarrier mapper having one or more processing circuits configured to:

determine a first subset of samples from the set of reference signal samples that have contiguous index values, wherein a first sample of the first subset of samples has a lowest index value in the set of consecutive index values;

determine a second subset of samples from the set of reference signal samples that have contiguous index values, wherein a last sample of the second subset of samples has a highest index value in the set of consecutive index values, wherein each index value of the second subset of samples is higher than each index value of the first subset of samples, and wherein each sample in the set is included in one of the first or second subsets of samples;

map the second subset of samples to a first subset of subcarriers of the bandwidth, including mapping a first sample of the second subset of samples having a lowest index value of the second subset of samples to a first subcarrier at a first end of the bandwidth; and

map the first subset of samples to a second subset of subcarriers of the bandwidth, including mapping a last sample of the first subset of samples having a highest index value of the first subset of samples to a last subcarrier at an opposite second end of the bandwidth.

9. The wireless terminal of claim 8 , wherein:

the one or more processing circuits are configured to contiguously map the first subset of samples to the second subset of subcarriers; and

the one or more processing circuits are configured to contiguously map the second subset of samples to the first subset of subcarriers.

10. The wireless terminal of claim 8 :

wherein the first subset of subcarriers spans over a first portion of the bandwidth;

wherein the second subset of subcarriers spans over a different second portion of the bandwidth;

wherein the one or more processing circuits are further configured to map a third subset of samples to a third subset of subcarriers of the bandwidth;

wherein the third subset of subcarriers span over a third portion of the bandwidth that is situated between the first and second portions of the bandwidth; and

wherein the first, second, and third portions of the bandwidth do not overlap.

11. The wireless terminal of claim 10 , wherein:

the first and second subsets of samples are from a first reference signal sequence; and

the third subset of samples is from a second reference signal sequence.

12. The wireless terminal of claim 8 , wherein the reference signal samples are one of Sounding Reference Signal (SRS) samples and Demodulation Reference Sequence (DMRS) samples.

13. The wireless terminal of claim 8 , wherein the channel comprises a Physical Uplink Shared Channel (PUSCH) in a Long Term Evolution (LTE) network.

14. The wireless terminal of claim 8 , wherein the first subcarrier at the first end of the bandwidth has a lowest frequency of the subcarriers within the bandwidth, and the last subcarrier at the opposite second end of the bandwidth has a highest frequency of the subcarriers within the bandwidth.

15. A method, performed by a base station, of demapping subcarriers received within a bandwidth allocated for transmission over a channel to a set of reference signal samples, such that each sample has an associated index value from a set of consecutive index values, and the set of reference signal samples are consecutively ordered by their index value, the method comprising:

determining a first subset of the subcarriers of the bandwidth, wherein a first subcarrier of the first subset of subcarriers has a lowest frequency of the subcarriers;

determining a second subset of the subcarriers, wherein a last subcarrier of the second subset of subcarriers has a highest frequency of the subcarriers, and wherein the frequency of each subcarrier in the second subset of subcarriers is higher than the frequency of each subcarrier in the first subset of subcarriers;

demapping the second subset of subcarriers to a first subset of samples having contiguous index values, such that a first subcarrier of the second subset of subcarriers having a lowest frequency of the second subset of subcarriers is demapped to have an index value at a first end of the range of index values; and

demapping the first subset of subcarriers to a second subset of samples having contiguous index values, such that a last subcarrier of the first subset of subcarriers having a highest frequency of the first subset of subcarriers is demapped to have an index value at an opposite second end of the range of index values, wherein each sample in the set of reference signal samples is included in one of the first or second subsets of samples.

16. The method of claim 15 , wherein:

the second subset of subcarriers are contiguously demapped to the first subset of samples; and

the first subset of subcarriers are contiguously demapped to the second subset of samples.

17. The method of claim 15 , wherein the first subset of subcarriers spans over a first portion of the bandwidth, and the second subset of subcarriers spans over a different second portion of the bandwidth, the method further characterized by:

demapping a third subset of subcarriers of the bandwidth to a third subset of samples;

wherein the third subset of subcarriers span over a third portion of the bandwidth that is situated between the first and second portions of the bandwidth; and

wherein the first, second, and third portions of the bandwidth do not overlap.

18. The method of claim 17 , wherein:

the first and second subsets of samples form a first reference signal sequence; and

the third subset of samples form a second reference signal sequence.

19. The method of claim 15 , wherein the reference signal samples are one of Sounding Reference Signal (SRS) samples and Demodulation Reference Sequence (DMRS) samples.

20. The method of claim 15 , wherein the channel comprises a Physical Uplink Shared Channel (PUSCH) in a Long Term Evolution (LTE) network.

21. The method of claim 15 , wherein the index value at the first end of the range of index values is a lower index value than the index value at the opposite second end of the range of index values.

22. A base station operative to demap subcarriers received within a bandwidth allocated for transmission over a channel to a set of reference signal samples, such that each sample has an associated index value from a range of consecutive index values, and the set of reference signal samples are consecutively ordered by their index value, the base station comprising:

a subcarrier demapper including one or more processing circuits configured to:

determine a first subset of the subcarriers of the bandwidth, wherein a first subcarrier of the first subset of subcarriers has a lowest frequency of the subcarriers;

determine a second subset of the subcarriers, wherein a last subcarrier of the second subset of subcarriers has a highest frequency of the subcarriers, and wherein the frequency of each subcarrier in the second subset of subcarriers is higher than the frequency of each subcarrier in the first subset of subcarriers;

demap the second subset of subcarriers to a first subset of reference signal samples having contiguous index values, such that a first subcarrier of the second subset of subcarriers having a lowest frequency of the second subset of subcarriers is demapped to have an index value at a first end of the range of index values; and

demap the first subset of subcarriers to a second subset of reference signal samples having contiguous index values, such that a last subcarrier of the first subset of subcarriers having a highest frequency of the first subset of subcarriers is demapped to have an index value at an opposite second end of the range of index values, wherein each sample in the set of reference signal samples is included in one of the first or second subsets of samples.

23. The base station of claim 22 , wherein:

the one or more processing circuits are configured to contiguously demap the second subset of subcarriers to the first subset of samples; and

the one or more processing circuits are configured to contiguously demap the first subset of subcarriers to the second subset of samples.

24. The base station of claim 22 :

wherein the first subset of subcarriers spans over a first portion of the bandwidth;

wherein the second subset of subcarriers spans over a different second portion of the bandwidth;

wherein the one or more processing circuits are further configured to demap a third subset of subcarriers of the bandwidth to a third subset of samples;

wherein the third subset of subcarriers span over a third portion of the bandwidth that is situated between the first and second portions of the bandwidth; and

wherein the first, second, and third portions of the bandwidth do not overlap.

25. The base station of claim 24 , wherein:

the first and second subsets of samples form a first reference signal sequence; and

the third subset of samples form a second reference signal sequence.

26. The base station of claim 22 , wherein the reference signal samples are one of Sounding Reference Signal (SRS) samples and Demodulation Reference Sequence (DMRS) samples.

27. The base station of claim 22 , wherein the channel comprises a Physical Uplink Shared Channel (PUSCH) in a Long Term Evolution (LTE) network.

28. The base station of claim 22 , wherein the index value at the first end of the range of index values is a lower index value than the index value at the opposite second end of the range of index values.