Two-tone physical uplink shared channel for machine type communications

1. One or more non-transitory computer-readable media (NTCRM) having instructions that, when executed by one or more processors, cause a user equipment (UE) to:

map a demodulation reference signal (DMRS) to resource elements within a sub-physical resource block (PRB) physical uplink shared channel (PUSCH) allocation based on a sub-PRB configuration of a PUSCH allocation, wherein the sub-PRB configuration is a 2 out of 3 subcarrier configuration, wherein the 2 out of 3 subcarrier configuration indicates a configuration of 2 adjacent subcarriers out of 3 allocated subcarriers including a subcarrier x, a subcarrier x+1, and a subcarrier x+2; and

cause the DMRS to be transmitted.

2. The one or more NTCRM of claim 1 , wherein the DMRS has a length-16 sequence, or a length-12 sequence.

3. The one or more NTCRM of claim 1 , wherein to map the DMRS includes to map the DMRS to resource elements in a fourth symbol in each of a plurality of consecutive slots, and wherein each of the plurality of consecutive slots are 4 milliseconds.

4. The one or more NTCRM of claim 1 , wherein the sub-PRB PUSCH allocation comprises 2 out of 3 allocated subcarriers.

5. The one or more NTCRM of claim 1 , wherein the DMRS is a first DMRS and the instructions, when executed, are further to cause the UE to:

map the first DMRS to a first subcarrier of the 2 out of 3 allocated subcarriers; and

map a second DMRS to a second subcarrier of the 2 out of 3 allocated subcarriers.

6. The one or more NTCRM of claim 1 , wherein the DMRS is mapped to one subcarrier.

7. The one or more NTCRM of claim 1 , wherein the DMRS comprises 2-tone binary phase shift keying (BPSK) DMRS symbols and the instructions, when executed, are further to cause the UE to:

apply discrete Fourier transforming pre-coding to the 2-tone BPSK DMRS symbols; and

cause the DMRS to be transmitted on one subcarrier.

8. The one or more NTCRM of claim 1 , wherein the instructions, when executed, are further to cause the UE to map the DMRS to resource elements in a fourth symbol in each of a plurality of consecutive slots.

9. An apparatus, comprising:

memory to include information to configure a user equipment (UE) with a plurality of sub-physical resource block (PRB) configurations; and

baseband circuitry to:

receive an indication of capability information for the UE with respect to a sub-PRB allocation;

construct, based on the capability information, a configuration message to configure the UE with one or more sub-PRB configurations for a physical uplink shared channel (PUSCH), wherein a first sub-PRB configuration of the one or more sub-PRB configurations is a 2 out of 3 subcarrier configuration, wherein the 2 out of 3 subcarrier configuration indicates a configuration of 2 adjacent subcarriers out of 3 allocated subcarriers including a subcarrier x, a subcarrier x+1, and a subcarrier x+2, and wherein resource elements within a sub-PRB determined by the first sub-PRB configuration are used to carry a demodulation reference signal (DMRS) from the UE; and

cause the configuration message to be sent to the UE.

10. The apparatus of claim 9 , wherein the baseband circuitry is further configured to:

cause an allocation message to be sent to the UE to indicate the 2 out of 3 allocated subcarriers; and

receive the PUSCH transmission from the UE on the 2 out of 3 allocated subcarriers, with a 15 kHz subcarrier spacing.

11. The apparatus of claim 9 , wherein the 2 out of 3 allocated subcarriers are based on a plurality of non-overlapping sets of subcarriers, and the 3 allocated subcarriers are based on the plurality of non-overlapping sets of subcarriers.

12. The apparatus of claim 11 , wherein the plurality of non-overlapping sets of subcarriers include subcarrier sets {0, 1, 2}, {3, 4, 5}, {6, 7, 8} and {9, 10, 11}.

13. The apparatus of claim 9 , wherein the baseband circuitry is further configured to:

generate and cause transmission of downlink control information that includes M bits in a subcarrier indication field to indicate a set of allocated subcarriers.

14. The apparatus of claim 9 , wherein the indication of capability information is to indicate support for a 2 out of 3 subcarrier configuration, a 3-subcarrier configuration, or a 6-subcarrier configuration.

15. The apparatus of claim 9 , wherein the one or more sub-PRB configurations further include a 3-subcarrier configuration or a 6-subcarrier configuration.

16. The apparatus of claim 9 , wherein the baseband circuitry is further configured to:

indicate the set of allocated subcarriers based on the following table:

I sc

n sc

0-3

3I sc + {Y, Y + 1}

4-7

3(I sc − 4) + {0, 1, 2}

8-9

6(I sc − 8) + {0, 1, 2, 3, 4, 5}

wherein n SC is the set of allocated subcarriers, I SC is indicated by the M bits in the subcarrier indication field, and Y is 0 or 1.

17. A method, comprising:

mapping a demodulation reference signal (DMRS) to resource elements within a sub-physical resource block (PRB) physical uplink shared channel (PUSCH) allocation based on a sub-PRB configuration of a PUSCH allocation, wherein the sub-PRB configuration is a 2 out of 3 subcarrier configuration that indicates a configuration of 2 adjacent subcarriers out of 3 allocated subcarriers including a subcarrier x, a subcarrier x+1, and a subcarrier x+2; and

transmitting the DMRS to a base station.

18. The method of claim 17 , wherein the mapping the DMRS includes mapping the DMRS to resource elements in a fourth symbol of a plurality of consecutive slots.

19. The method of claim 17 , wherein the sub-PRB PUSCH allocation comprises 2 out of 3 allocated subcarriers.

20. The method of claim 17 , wherein the DMRS is a first DMRS, the method further comprising:

mapping the first DMRS to a first subcarrier of the 2 out of 3 allocated subcarriers; and

mapping a second DMRS to a second subcarrier of the 2 out of 3 allocated subcarriers.