Systems and methods for selecting subcarriers for sub-PRB transmissions
Systems and methods for selecting subcarriers to be used for sub-Physical Resource Block (PRB) transmission and, in some embodiments, for mapping Demodulation Reference Signals (DMRS) to resources on the selected subcarriers are disclosed. In some embodiments, a method of operation of a radio node for providing sub-PRB transmission comprises selecting two adjacent subcarriers from a set of three allocated subcarriers that are allocated for a sub-PRB transmission that uses Single Carrier Frequency Division Multiple Access (SC-FDMA) Pi/2 Binary Phase Shift Keying (BPSK) modulation using only two adjacent subcarriers out of the set of three allocated subcarriers with Discrete Fourier Transform (DFT) spread length of 2. In some embodiments, the selection is such that the selected adjacent subcarriers varies, e.g., from one cell to another. In doing so, interference is distributed.
1. A method of operation of a radio node for providing sub-Physical Resource Block (sub-PRB) transmission, comprising:
selecting two adjacent subcarriers from a set of three allocated subcarriers that are allocated for a sub-PRB transmission that uses Single Carrier Frequency Division Multiple Access (SC-FDMA) Pi/2 Binary Phase Shift Keying (BPSK) modulation using only two adjacent subcarriers out of the set of three allocated subcarriers with Discrete Fourier Transform (DFT) spread length of 2,
wherein selecting the two adjacent subcarriers from the set of three allocated subcarriers comprises selecting the two adjacent subcarriers based on a cell Identifier, ID, of a cell that has allocated the sub-PRB transmission.
2. The method of claim 1 further comprising performing one or more tasks related to the sub-PRB transmission.
3. The method of claim 2 wherein performing the one or more tasks comprises performing the sub-PRB transmission using SC-FDMA Pi/2 BPSK modulation using only the two selected adjacent subcarriers out of the set of three allocated subcarriers with DFT-spread length of 2.
4. The method of claim 1 wherein selecting the two adjacent subcarriers based on the cell ID of the cell that has allocated the sub-PRB transmission comprises selecting the two adjacent subcarriers based on a value resulting from the cell ID modulo 2 operation.
5. The method of claim 4 wherein the two adjacent subcarriers are two subcarriers with lowest indexes among the set of three allocated subcarriers if the value is “0” and the two adjacent subcarriers are two subcarriers with the highest indexes among the set of three allocated subcarriers if the value is “1”.
6. The method of claim 1 wherein Demodulation Reference Signal, DMRS, is mapped to the two selected adjacent subcarriers in accordance with an alternating pattern.
7. The method of claim 1 wherein Demodulation Reference Signal, DMRS, is mapped to the two selected adjacent subcarriers in accordance with a deterministic alternating pattern.
8. The method of claim 1 wherein the radio node is a base station.
9. A radio node for providing sub-Physical Resource Block (sub-PRB) transmission, comprising:
processing circuitry configured to cause the radio node to select two adjacent subcarriers from a set of three allocated subcarriers that are allocated for a sub-PRB transmission that uses Single Carrier Frequency Division Multiple Access (SC-FDMA) Pi/2 Binary Phase Shift Keying (BPSK) modulation using only two adjacent subcarriers out of the set of three allocated subcarriers with Discrete Fourier Transform (DFT) spread length of 2,
wherein selecting the two adjacent subcarriers from the set of three allocated subcarriers comprises selecting the two adjacent subcarriers based on a cell Identifier, ID, of a cell that has allocated the sub-PRB transmission.
10. The radio node of claim 9 wherein the processing circuitry is further configured to perform one or more tasks related to the sub-PRB transmission.
11. The radio node of claim 10 wherein performing the one or more tasks comprises performing the sub-PRB transmission using SC-FDMA Pi/2 BPSK modulation using only the two selected adjacent subcarriers out of the set of three allocated subcarriers with DFT-spread length of 2.
12. The radio node of claim 10 wherein performing the one or more tasks comprises sending information that indicates the two selected adjacent subcarriers to another node.
13. The radio node of claim 10 wherein selecting the two adjacent subcarriers based on the cell ID of the cell that has allocated the sub-PRB transmission comprises selecting the two adjacent subcarriers based on a value resulting from the cell ID modulo 2 operation.
14. The radio node of claim 13 wherein the two adjacent subcarriers are two subcarriers with lowest indexes among the set of three allocated subcarriers if the value is “0” and the two adjacent subcarriers are two subcarriers with the highest indexes among the set of three allocated subcarriers if the value is “1”.
15. The radio node of claim 9 wherein Demodulation Reference Signal, DMRS, is mapped to the two selected adjacent subcarriers in accordance with an alternating pattern.
16. The radio node of claim 9 wherein Demodulation Reference Signal, DMRS, is mapped to the two selected adjacent subcarriers in accordance with a deterministic alternating pattern.
17. The radio node of claim 9 wherein selecting the two adjacent subcarriers from the set of three allocated subcarriers comprises selecting the two adjacent subcarriers based on whether a cell that has allocated the sub-PRB transmission is either “even” or “odd”.
18. The radio node of claim 9 wherein selecting the two adjacent subcarriers from the set of three allocated subcarriers comprises selecting the two adjacent subcarriers randomly per cell.
19. The radio node of claim 9 wherein Demodulation Reference Signal, DMRS, is mapped to the two selected adjacent subcarriers in accordance with a predefined pattern.
20. The radio node of claim 19 wherein the predefined pattern is a periodic pattern that alternates the DMRS mapping among the two selected adjacent subcarriers.
21. The radio node of claim 19 wherein the predefined pattern is a pseudorandom pattern that maps DMRS among the two selected adjacent subcarriers.
22. The radio node of claim 9 wherein Demodulation Reference Signal, DMRS, is mapped to only one of the two selected adjacent subcarriers in a predefined manner.
23. The radio node of claim 22 wherein the one of the two selected adjacent subcarriers to which DMRS is mapped is a center subcarrier of the set of three allocated subcarriers.