ACK/NACK signals for next generation LTE devices and systems
Devices and methods of providing symmetric UL and DL ACK/NACKs is generally described. UL ACK/NACKs of different UEs are multiplexed and received by a UE with a PUSCH. The receiving UE in response transmits the DL ACK/NACK. The ACK/NACK may be transmitted in a localized or distributed manner among subbands that may be adjacent or each may have blocks separated by blocks of a different subband. The ACK and NACK may use independent resources or the NACK may not be transmitted on the single ACK/NACK resource, the lack of an ACK serving as a NACK. The ACK/NACK may be transmitted using a beamforming weight shaped by the received PUSCH/PDSCH. The ACK/NACK symbol may be located in the first symbol, adjacent to the PUSCH/PDSCH, or at the end of a TTI. If adjacent, the UL grant or UL assignment may indicate whether the ACK/NACK resource is used by the PUSCH/PDSCH.
1. An apparatus comprising: processing circuitry configured to cause a user equipment (UE) arranged to:
decode, from an evolved NodeB (eNB) a physical downlink shared channel (PDSCH);
in response to the PD SCH, generate a Hybrid Automatic Repeat Request Acknowledgement/Negative Acknowledgement (HARQ ACK/NACK), the HARQ ACK/NACK generated using:
r ( n )=exp( jαn )· r u,v ( n )
where r u,v (n) is a base sequence; u is a sequence group number, v is a sequence number and α is a cyclic shift that is different for an ACK than for a NACK, wherein the cyclic shift is determined from a function of an initial cyclic shift, a cell id, and a predetermined constant shift dependent on whether the UL HARQ ACK/NACK is a UL HARQ ACK or a UL HARQ NACK, and modulus-12 operation performed on the function; and
encode the HARQ ACK/NACK for transmission to the eNB in a physical uplink control channel (PUCCH); and
memory configured to store the HARQ ACK/NACK.
2. The apparatus of claim 1 , wherein:
the cyclic shift varies as a function of a symbol and slot number of the PUCCH.
3. The apparatus of claim 2 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence, and
the processing circuitry is further arranged to determine the base sequence as a function of a physical cell identity of the eNB.
4. The apparatus of claim 2 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence, and
the processing circuitry is further arranged to determine the base sequence as a function of a virtual cell identity of the eNB.
5. The apparatus of claim 2 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence, and
the processing circuitry is further arranged to determine the base sequence as a function of at least one of slot index of the PUCCH, a subframe index of the PUCCH, or a frame index of the PUCCH.
6. The apparatus of claim 1 , wherein:
the processing circuitry is further arranged to decode, from the eNB, a physical downlink control channel (PDCCH) that comprises a UL grant to transmit the PUSCH, and
the UL grant comprises an indicator that indicates one of a plurality of values in which one value indicates that a HARQ ACK/NACK resource for HARQ ACK/NACK symbols is to be free from mapping of the PUSCH to the HARQ ACK/NACK resource and another value indicates the PUSCH is to be mapped to the HARQ ACK/NACK resource.
7. The apparatus of claim 1 , wherein the processing circuitry is further arranged to:
apply a repetition code of a predetermined length to an ACK/NACK bit to form a repeated bit,
modulate the repeated bit using one of binary phase shift keying (BPSK) and quadrature PSK (QPSK) to form a modulated symbol,
apply a spreading code to the modulated symbol to form a spread symbol,
apply cell-specific scrambling to the spread symbol to form a scrambled symbol, a scrambling seed of the cell-specific scrambling defined as a function of at least one of a physical cell identity of the eNB, a virtual cell identity of the eNB, a slot index of the PUCCH, a subframe index of the PUCCH and a frame index of the PUCCH, and
map the scrambled signal starting from a lowest frequency index within an allocated subband to form a modulated ACK/NACK symbol of the HARQ ACK/NACK.
8. The apparatus of claim 1 , wherein:
an ACK/NACK resource of the HARQ ACK/NACK is a function of subband index (I SB ) and spreading code index (I SF ) used for the HARQ ACK/NACK,
a resource index for the HARQ ACK/NACK is a function of at least one of a cell-specific parameter, a UE-specific parameter, a parameter signaled in a Downlink Control Information (DCI) format, and, as used for one of the PDSCH and a physical uplink shared channel (PUSCH), at least one of: a beamforming index, a slot index, a subframe index, a frame index and a physical resource block index, and
the cell-specific parameter is configured by master information block (MIB), system information block (SIB) or dedicated Radio Resource Control (RRC) signaling, the UE-specific parameter is configured from one of a primary cell and a serving cell via dedicated RRC signaling, and the parameter signaled in the DCI format is one of the sub band index and a Demodulation Reference Signal (DM-RS) used for the one of the PDSCH and PUSCH.
9. The apparatus of claim 1 , wherein the processing circuitry is further arranged to:
time-division multiplex the HARQ ACK/NACK with a physical uplink control channel (PUCCH), the HARQ ACK/NACK transmitted in a beamformed HARQ ACK/NACK channel, and
dynamically shape a beamforming weight of the HARQ ACK/NACK channel to follow beamforming of a previous PUSCH such that a transmit analog beam direction of the HARQ ACK/NACK channel is based on the previous PUSCH, and digital precoding of the HARQ ACK/NACK channel is based on a channel estimation obtained from an UL Demodulation Reference Signal (DM-RS) transmitted from the UE.
10. The apparatus of claim 1 , wherein:
the processing circuitry is further arranged to time-division multiplex the HARQ ACK/NACK with a physical uplink control channel (PUCCH), the HARQ ACK/NACK transmitted in a beamformed HARQ ACK/NACK channel, and
a HARQ ACK/NACK symbol is a first symbol of a DL Transmission Time Interval (TTI),
the HARQ ACK/NACK symbol is adjacent to the PDSCH,
the HARQ ACK/NACK channel is disposed at an end of the DL TTI after the PD SCH.
11. The apparatus of claim 1 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence (x u (n)), and
the processing circuitry is further arranged to, if a ZC sequence length (Nzc) is less than a subband size (K), generate the base sequence using a cyclic extension for the ZC sequence:
r u,v ( n )= x q ( n mod N ZC ),0≤ n≤K.
12. The apparatus of claim 1 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence (x u , (n)), and
the processing circuitry is further arranged to, if a ZC sequence length (Nzc) is less than a subband size (K), generate the base sequence by puncturing a carrier in the subband such that:
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with the ZC sequence:
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13. The apparatus of claim 1 , wherein:
the sequence is a Zadoff-Chu (ZC) sequence (x u (n)), and
the processing circuitry is further arranged to, if a ZC sequence length (Nzc) is larger than a subband size (K), generate the base sequence by puncturing an element in the ZC sequence such that:
r u,v ( n )= x q ( n ),0≤ n≤K.
14. The apparatus of claim 1 , wherein the processing circuitry is further arranged to:
generate a scrambling seed, the scrambling seed using n s is a slot index of the HARQ ACK/NACK and N cell ID is a cell identifier (ID) of the eNB:
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init
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ID
apply, using the scrambling seed, cell-specific scrambling to a symbol of the HARQ ACK/NACK to form a scrambled symbol prior to transmission of the HARQ ACK/NACK.
15. The apparatus of claim 1 , wherein:
the processing circuitry is further arranged to decode, from the eNB, a HARQ ACK/NACK received in a channel in which HARQ ACK/NACKs for multiple UEs are multiplexed in at least one of a time-division multiplexing (TDM), frequency-division multiplexing (FDM) and code-division multiplexing (CDM) manner, which is downconverted to baseband by mixer circuitry prior to the resource being determined.
16. The apparatus of claim 1 , wherein the initial cyclic shift is provided by higher layers via dedicated UE specific RRC signaling.
17. An apparatus of an evolved NodeB (eNB) comprising:
processing circuitry arranged to:
encode, for transmission to a user equipment (UE), a physical downlink shared channel (PDSCH); and
decode, from the UE in response to transmission of the PDSCH, a Hybrid Automatic Repeat Request Acknowledgement/Negative Acknowledgement (HARQ ACK/NACK) in a physical uplink control channel (PUCCH), the HARQ ACK/NACK being:
r ( n )=exp( jαn )· r u,v ( n )
where r u,v (n) is a base sequence; u is a sequence group number, v is a sequence number and α is a cyclic shift that is different for an ACK than for a NACK, wherein the cyclic shift is determined from a function of an initial cyclic shift, a cell id, and a predetermined constant shift dependent on whether the UL HARQ ACK/NACK is a UL HARQ ACK or a UL HARQ NACK, and modulus-12 operation performed on the function; and
memory configured to store the HARQ ACK/NACK.
18. The apparatus of claim 17 , wherein:
an ACK/NACK resource of the HARQ ACK/NACK is a function of subband index (I SB ) and spreading code index (I SF ) used for the HARQ ACK/NACK,
a resource index for the HARQ ACK/NACK is a function of at least one of a cell-specific parameter, a UE-specific parameter, a parameter signaled in a Downlink Control Information (DCI) format, and, as used for one of the PDSCH and a physical uplink shared channel (PUSCH), at least one of: a beamforming index, a slot index, a subframe index, a frame index and a physical resource block index, and
the cell-specific parameter is configured by master information block (MIB), system information block (SIB) or dedicated Radio Resource Control (RRC) signaling, the UE-specific parameter is configured from one of a primary cell and a serving cell via dedicated RRC signaling, and the parameter signaled in the DCI format is one of the subband index and a Demodulation Reference Signal (DM-RS) used for the one of the PDSCH and PUSCH.
19. An apparatus comprising:
a transceiver arranged to communicate with a base station; and
processing circuitry arranged to cause a user equipment (UE) to:
configure the transceiver to receive from the eNB a physical downlink shared channel (PDSCH) associated with the UE;
determine a resource for a downlink (DL) HARQ ACK/NACK in response to the PDSCH; and
configure the transceiver to transmit to the eNB the DL HARQ ACK/NACK, wherein the DL HARQ ACK/NACK uses a same base sequence but different cyclic shifts dependent on whether the UL HARQ ACK/NACK is a UL HARQ ACK or a UL HARQ NACK, wherein the cyclic shift is determined from a function of an initial cyclic shift, a cell id, and a predetermined constant shift dependent on whether the UL HARQ ACK/NACK is a UL HARQ ACK or a UL HARQ NACK, and modulus-12 operation performed on the function.
20. The apparatus of claim 19 , wherein the initial cyclic shift is provided by higher layers via dedicated UE specific RRC signaling.