8TX codebook enhancements

1 . A method for wireless communication, comprising:

receiving, at a wireless device from a wireless communication node, a configuration that indicates at least one of one or more numbers of port groups for uplink transmissions from the wireless device, wherein a total number of ports is eight;

determining, at the wireless device, a precoder for an uplink transmission according to the configuration, wherein the precoder is determined from a set of candidate precoders that is reduced by one or more rules that specify a starting port index and a predefined port index order for each candidate precoder in the set; and

performing, at the wireless device, the uplink transmission using the precoder.

2 . The method of claim 1 , wherein the one or more numbers of port groups indicated by the configuration is one or more of: one port group, two port groups, four port groups, or eight port groups.

3 . The method of claim 1 , further comprising:

transmitting, to the wireless communication node, information that indicates one or more supported numbers of port groups.

4 . The method of claim 1 , wherein an indicated number of port groups is a highest capability that indicates that one or more capabilities lower than the highest capability are configured or supported, and wherein an order of port group capabilities from highest to lowest is one port group, two port groups, four port groups, and eight port groups.

5 . The method of claim 1 , wherein determining a precoder for a transmission according to the configuration includes:

determining at least one of a rank, a number of layers, or a transmit precoding matrix indicator (TPMI) for each port group of the at least one number of port groups indicated by the configuration.

6 . The method of claim 5 , wherein an indication of number of port groups is included in a downlink control information (DCI), a medium access control control element (MAC CE) or a radio resource control (RRC) signaling.

7 . The method of claim 1 , wherein the configuration is received via one of a radio resource control (RRC) signaling, a medium access control (MAC) control element, or a downlink control indicator (DCI).

8 . The method of claim 1 , further comprising:

mapping ports of one or more port groups to ports of the precoder according to at least one of one or more pre-defined mappings.

9 . The method of claim 8 , wherein the one or more pre-defined mappings include:

a mapping of two port groups each having four ports to ports {0,1,4,5,2,3,6,7} of the precoder, or

a mapping of four port groups each having two ports to ports {0,4,1,5,2,6,3,7} of the precoder.

10 . A method for wireless communication, comprising:

transmitting, to a wireless communication device, a configuration that indicates at least one of one or more numbers of port groups for uplink transmissions from the wireless communications device, wherein a total number of ports is eight; and

indicating, to the wireless communication device, a precoder for a transmission according to the configuration, or an indication of number of port groups, wherein the precoder is determined from a set of candidate precoders that is reduced by one or more rules that specify a starting port index and a predefined port index order for each candidate precoder in the set.

11 . The method of claim 10 , wherein the one or more port groups comprise one or more of: one port group, two port groups, four port groups, or eight port groups.

12 . The method of claim 10 , wherein an indicated number of port groups is a highest capability that indicates that one or more capabilities lower than the highest capability are supported or configured.

13 . The method of claim 12 , wherein an order of port group capabilities from highest to lowest is one port group, two port groups, four port groups, and eight port groups.

14 . The method of claim 10 , wherein the indication of number of port groups is included in a downlink control information (DCI), a medium access control control element (MAC CE) or a radio resource control (RRC) signaling.

15 . The method of claim 10 , further comprising:

indicating a number of antenna elements for a polarization direction in the configuration.

16 . The method of claim 10 , wherein the configuration is transmitted via one of a downlink control information (DCI), a medium access control control element (MAC CE) or a radio resource control (RRC) signaling.

17 . An apparatus for wireless communication, comprising a memory and at least one processor, wherein the at least one processor executes instructions stored on the memory to implement a method comprising:

receiving, from a wireless communication node, a configuration that indicates at least one of one or more numbers of port groups for uplink transmissions, wherein a total number of ports is eight;

determining a precoder for an uplink transmission according to the configuration, wherein the precoder is determined from a set of candidate precoders that is reduced by one or more rules that specify a starting port index and a predefined port index order for each candidate precoder in the set; and

performing the uplink transmission using the precoder.

18 . An apparatus for wireless communication, comprising a memory and at least one processor, wherein the at least one processor executes instructions stored on the memory to implement a method comprising:

transmitting, to a wireless communication device, a configuration that indicates at least one of one or more numbers of port groups for uplink transmissions from the wireless communications device, wherein a total number of ports is eight; and

indicating, to the wireless communication device, a precoder for a transmission according to the configuration, or an indication of number of port groups, wherein the precoder is determined from a set of candidate precoders that is reduced by one or more rules that specify a starting port index and a predefined port index order for each candidate precoder in the set.