Uplink transmission techniques in low latency wireless communication systems
Symbol alignment and power scaling are provided for different length transmission time intervals (TTIs) within predefined boundaries, such as boundaries of a slot of a subframe. Described techniques provide for identifying time and/or frequency resources for one or more TTIs and allocating such resources based on a location within a subframe, pilot signals that may be transmitted using the resources, other processing timelines, or any combination thereof. In some cases, a power allocation for symbols within a TTI may be determined based on the allocated resources for the TTI. Frequency hopping patterns and power scaling for three-symbol TTIs are also provided.
1. A method for wireless communication, comprising:
receiving an uplink resource allocation for an uplink transmission, the uplink resource allocation identifying an uplink transmission time interval (TTI) including a number of symbols;
identifying a first frequency resource for transmitting a first subset of the symbols based at least in part on the uplink resource allocation;
identifying a second frequency resource for transmitting a second subset of the symbols based at least in part on the uplink resource allocation; and
transmitting the uplink transmission using the first frequency resource and the second frequency resource, wherein the first subset of the symbols, the second subset of the symbols, or both, includes both a data signal and a pilot signal.
2. The method of claim 1 , wherein the first subset of the symbols has two symbols and the second subset of the symbols has one symbol.
3. The method of claim 2 , further comprising:
configuring a first symbol of the first subset of the symbols for a pilot signal transmission and a second symbol of the first subset of the symbols for a data transmission.
4. The method of claim 2 , further comprising:
configuring the one symbol of the second subset of the symbols for transmission of both data and a pilot signal.
5. The method of claim 1 , wherein the first subset of the symbols is to be transmitted at a beginning of a wireless transmission subframe, and wherein the first subset of the symbols has two symbols.
6. The method of claim 5 , wherein a first symbol of the first subset of the symbols is located at the beginning of the wireless transmission subframe and is unallocated for data or pilot signal transmissions and a second symbol of the first subset of the symbols is allocated for transmission of both data and a pilot signal.
7. The method of claim 1 , wherein the second subset of the symbols is to be transmitted at an end of a wireless transmission subframe, and wherein the second subset of the symbols has two symbols.
8. The method of claim 7 , wherein a last symbol of the second subset of the symbols is located at the end of the wireless transmission subframe and is configured for a sounding reference signal (SRS) transmission, and wherein a first symbol of the second subset of the symbols that precedes the last symbol of the second subset of the symbols is allocated for transmission of both data and a pilot signal.
9. The method of claim 1 , further comprising:
identifying a first transmission power for the first subset of the symbols, wherein the first subset of the symbols has two symbols; and
applying a power offset to the first transmission power to determine a second transmission power for the second subset of the symbols, wherein the second subset of the symbols has one symbol.
10. The method of claim 9 , wherein the power offset increases a transmission power for the second subset of the symbols to compensate for reduced time diversity and achievable energy per bit of the second subset of the symbols relative to the first subset of the symbols.
11. The method of claim 9 , further comprising:
receiving the power offset with the uplink resource allocation.
12. The method of claim 9 , further comprising:
receiving, prior to the receiving the uplink resource allocation, a configuration with the power offset.
13. The method of claim 1 , wherein the number of symbols are contained within a slot, and wherein the uplink transmission is a physical uplink control channel transmission.
14. An apparatus for wireless communication, comprising:
one or more processors,
one or more memories coupled with the one or more processors; and
instructions stored in the one or more memories and executable by the one or more processors to cause the apparatus to:
receive an uplink resource allocation for an uplink transmission, the uplink resource allocation identifying an uplink transmission time interval (TTI) including a number of symbols;
identify a first frequency resource for transmitting a first subset of the symbols based at least in part on the uplink resource allocation;
identify a second frequency resource for transmitting a second subset of the symbols based at least in part on the uplink resource allocation; and
transmit the uplink transmission using the first frequency resource and the second frequency resource, wherein the first subset of the symbols, the second subset of the symbols, or both, includes both a data signal and a pilot signal.
15. The apparatus of claim 14 , wherein the first subset of the symbols has two symbols and the second subset of the symbols has one symbol.
16. The apparatus of claim 15 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
configure a first symbol of the first subset of the symbols for a pilot signal transmission and a second symbol of the first subset of the symbols for a data transmission.
17. The apparatus of claim 15 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
configure the one symbol of the second subset of the symbols for transmission of both data and a pilot signal.
18. The apparatus of claim 14 , wherein the first subset of the symbols is to be transmitted at a beginning of a wireless transmission subframe, and wherein the first subset of the symbols has two symbols.
19. The apparatus of claim 18 , wherein a first symbol of the first subset of the symbols is located at the beginning of the wireless transmission subframe and is unallocated for data or pilot signal transmissions and a second symbol of the first subset of the symbols is allocated for transmission of both data and a pilot signal.
20. The apparatus of claim 14 , wherein the second subset of the symbols is to be transmitted at an end of a wireless transmission subframe, and wherein the second subset of the symbols has two symbols.
21. The apparatus of claim 20 , wherein a last symbol of the second subset of the symbols is located at the end of the wireless transmission subframe and is configured for a sounding reference signal (SRS) transmission, and wherein a first symbol of the second subset of the symbols that precedes the last symbol of the second subset of the symbols is allocated for transmission of both data and a pilot signal.
22. The apparatus of claim 14 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
identify a first transmission power for the first subset of the symbols, wherein the first subset of the symbols has two symbols; and
apply a power offset to the first transmission power to determine a second transmission power for the second subset of the symbols, wherein the second subset of the symbols has one symbol.
23. The apparatus of claim 22 , wherein the power offset increases a transmission power for the second subset of the symbols to compensate for reduced time diversity and achievable energy per bit of the second subset of the symbols relative to the first subset of the symbols.
24. The apparatus of claim 22 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive the power offset with the uplink resource allocation.
25. The apparatus of claim 22 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, prior to the reception of the uplink resource allocation, a configuration with the power offset.
26. The apparatus of claim 14 , wherein the number of symbols are contained within a slot, and wherein the uplink transmission is a physical uplink control channel transmission.
27. An apparatus for wireless communication, comprising:
one or more processors,
one or more memories coupled with the one or more processors; and
instructions stored in the one or more memories and executable by the one or more processors to cause the apparatus to:
transmit an uplink resource allocation for an uplink transmission, the uplink resource allocation identifying an uplink transmission time interval (TTI) including a number of symbols, wherein the uplink resource allocation comprises a first frequency resource for receiving a first subset of the symbols and a second frequency resource for receiving a second subset of the symbols; and
receive the uplink transmission using the first frequency resource and the second frequency resource, wherein the first subset of the symbols, the second subset of the symbols, or both, includes both a data signal and a pilot signal.