Method and apparatus for performing uplink transmission for NB-IoT in wireless communication system
A method and apparatus for transmitting a physical uplink shared channel (PUSCH) and a demodulation reference signal (DM-RS) in a wireless communication system is provided. A narrowband internet-of-things (NB-IoT) user equipment (UE) configures a set of resource units with at least one tone for uplink transmission in NB-IoT, transmits the PUSCH by using the set of resource units, and transmits the DM-RS used for demodulating the PUSCH by a network in the set of resource units.
1. A method for transmitting data and a demodulation reference signal (DM-RS) by a narrowband internet-of-things (NB-IoT) user equipment (UE) in a wireless communication system, the method comprising:
configuring a resource unit for a physical uplink shared channel (PUSCH) for the NB-IoT UE, wherein the resource unit consists of a single tone in a frequency domain;
mapping the data and the DM-RS to the resource unit;
transmitting the data and the DM-RS to a network,
wherein the DM-RS is phase-rotated by π/2 if the data is modulated by π/2 binary phase shift keying (BPSK), and
wherein the DM-RS is phase-rotated by π/4 if the data is modulated by π/4 quadrature phase shift keying (QPSK).
2. The method of claim 1 , wherein a length of the DM-RS is determined based on a number of symbols used for the DM-RS and a number of subframes in the resource unit.
3. The method of claim 1 , wherein the resource unit is a minimum resource block size where the PUSCH for the NB-IoT UE can be scheduled.
4. The method of claim 1 , wherein multiple resource units consists of one transmission time interval (TTI).
5. The method of claim 1 , wherein the resource unit corresponds to a subcarrier spacing of 3.75 kHz or 15 kHz.
6. The method of claim 1 , wherein the data is mapped first in frequency and second in time across a plurality of resource units.
7. The method of claim 1 , wherein the data is mapped first in time and second in frequency within the resource unit.
8. A narrowband internet-of-things (NB-IoT) user equipment (UE) in a wireless communication system, the NB-IoT UE comprising:
a memory;
a transceiver; and
a processor, coupled to the memory and the transceiver, that:
configures at least one resource unit for a physical uplink shared channel (PUSCH) for the NB-IoT UE, wherein the resource unit consists of a single tone in a frequency domain,
maps data and a demodulation reference signal (DM-RS) to the at least one resource unit,
controls the transceiver to transmit the data and the DM-RS to a network,
wherein the DM-RS is phase-rotated by π/2 if the data is modulated by π/2 binary phase shift keying (BPSK), and
wherein the DM-RS is phase-rotated by π/4 if the data is modulated by π/4 quadrature phase shift keying (QPSK).
9. The UE of claim 8 , wherein a length of the DM-RS is determined based on a number of symbols used for the DM-RS and a number of subframes in the resource unit.
10. The UE of claim 8 , wherein the resource unit is a minimum resource block size where the PUSCH for the NB-IoT UE can be scheduled.
11. The UE of claim 8 , wherein multiple resource units consists of one transmission time interval (TTI).
12. The UE of claim 8 , wherein the resource unit corresponds to a subcarrier spacing of 3.75 kHz or 15 kHz.
13. The UE of claim 8 , wherein the data is mapped first in frequency and second in time across a plurality of resource units.
14. The UE of claim 8 , wherein the data is mapped first in time and second in frequency within the resource unit.