Optimized signaling of demodulation reference signal patterns
Orthogonality in cyclic shift (CS) and orthogonal cover code (OCC) selection for DMRS in MIMO is improved by new n DMRS to n DMRS (2) mapping patterns. Values in the mapping tables are arranged in sets, with minimum CS separation between the values in each set. Additionally, the semi-static n DMRS is independently configurable for each UL component carrier (CC) in the case of cross-CC scheduling in carrier aggregation, and the PHICH allocation formula that defines the allocation of the PHICH process relative to the k th codeword (CW) on the c th UL CC is a function of both the CS index n DMRS,k,c (2) that is dynamically assigned to a certain layer of the considered CW and the semi-static CS offset n DMRS,c (1) for the c th CC.
1. A method of determining cyclic shift (CS) values associated with DeModulation Reference Signals (DMRS) for a plurality of transmission layers and allocating transmission resources, by a device in a wireless communication system employing Multiple Input Multiple Output (MIMO) operation and carrier aggregation, comprising:
receiving a semi-static cyclic shift (CS) value n DMRS,c (1) associated with each component carrier (CC) in the case of cross-CC scheduling; and
allocating transmission resources for a Physical Hybrid Automatic Repeat Request (HARQ) Channel (PHICH) transmission such that an allocation for a k th codeword on a c th CC is a function of both a first CS value n DMRS,k,c (2) associated with a DeModulation Reference Signal (DMRS) for a certain layer of a codeword and the semi-static CS value n DMRS,c (1) associated with the c th CC.
2. The method of claim 1 wherein allocating transmission resources comprises determining one or more resources to be used for a PHICH transmission based on values I PRB — RA lowest — index , N PHICH group , I PHICH and N SF PHICH , wherein N SF PHICH is spreading-factor size used for modulation of PHICH, I PRB — RA lowest — index is an index associated with a lowest physical resource block (PRB) index in a particular slot of a corresponding uplink control transmission, N PHICH group is a number of PHICH groups and is configured by higher layers, and I PHICH is a constant whose value depends on a time-division duplex (TDD) or frequency division duplex (FDD) configuration being used.
3. The method of claim 2 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) +n DMRS,c (1) )mod N PHICH group +I PHICH N PHICH group
n PHICH,k,c seq =(└ I PRB — RA lowest — index /N PHICH group ┘+n DMRS,k,c (2) +n DMRS,c (1) )mod 2 N SF PHICH .
4. The method of claim 2 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) +n DMRS,c (1) )mod N PHICH group +I PHICH N PHICH group
n PHICH,k,c seq =(└ I PRB RA lowest — index /N PHICH group ┘+n DMRS,k,c (2) )mod 2 N SF PHICH .
5. The method of claim 2 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) )mod N PHICH group +I PHICH N PHICH group
n PHICH,k,c seq =(└ I PRB — RA lowest — index /N PHICH group ┘+n DMRS,k,c (2) +n DMRS,k,c (1) )mod 2 N SF PHICH .
6. An apparatus for determining cyclic shift (CS) values associated with DeModulation Reference Signals (DMRS) for a plurality of transmission layers and allocating transmission resources in a wireless communication system employing Multiple Input Multiple Output (MIMO) operation and carrier aggregation, comprising:
a receiver operable to receive a semi-static cyclic shift (CS) value n DMRS,c (1) associated with each of one or more component carriers (CCs); and
a controller operable to allocate transmission resources for a Physical Hybrid Automatic Repeat Request (HARQ) Channel (PHICH) transmission such that an allocation for a k th codeword on a c th CC is a function of both a first CS value n DMRS,k,c (2) associated with a DeModulation Reference Signal (DMRS) for a particular layer of a codeword and the semi-static CS value n DMRS,c (1) associated with the c th CC.
7. The apparatus of claim 6 wherein the controller is operable to allocate transmission resources by determining one or more resources to be used for a PHICH transmission based on values I PRB — RA lowest — index , N PHICH group , I PHICH and N SF PHICH , wherein N SF PHICH is a spreading-factor size used for modulation of PHICH, I PRB — RA lowest — index is an index associated with a lowest physical resource block (PRB) index in a particular slot of a corresponding uplink control transmission, N PHICH group is a number of PHICH groups and is configured by higher layers, and I PHICH is a constant whose value depends on a time-division duplex (TDD) or frequency division duplex (FDD) configuration being used.
8. The apparatus of claim 7 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) +n DMRS,c (1) )mod N PHICH group +I PHICH N PHICH group
n PHICH,k,c seq =(└ PRB — RA lowest — index /N PHICH group ┘+n DMRS,k,c (2) +n DMRS,c (1) )mod 2 N SF PHICH .
9. The apparatus of claim 7 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) +n DMRS,c (1) )mod N PHICH group +I PHICH N PHICH group
PHICH,k,c seq =(└ I PRB RA lowest — index /N PHICH group ┘+n DMRS,k,c (2) )mod 2 N SF PHICH .
10. The apparatus of claim 7 , wherein determining the one or more resources comprises determining an index pair (n PHICH group , n PHICH seq ) associated with a first resource, wherein n PHICH group comprises a PHICH group number and n PHICH seq comprises an orthogonal signal index within the PHICH group number, and wherein:
n PHICH,k,c group =( I PRB — RA lowest — index +n DMRS,k,c (2) )mod N PHICH group +I PHICH N PHICH group
n PHICH,k,c seq =(└ I PRB — RA lowest — index /N PHICH group ┘+n DMRS,k,c +n DMRS,c (1) )mod 2 N SF PHICH .