Systems and methods for uplink DMRS enhancement in FD-MIMO

An apparatus of an evolved Node B (eNB) for wireless communication, the apparatus comprising:

• one or more processors configured to:
• generate a first uplink grant for a first user equipment (UE), the first uplink grant allocating a plurality of resource blocks (RBs) to the first UE;
• generate a second uplink grant for a second UE, the second uplink grant allocating a first portion of the RBs in the plurality of RBs to the second UE;
• and
• obtain an uplink transmission from the first UE, the uplink transmission having a first demodulation reference signal (DMRS) sequence for the first portion of the RBs in the plurality of RBs and having a second DMRS sequence for a second portion of the RBs in the plurality of RBs, the second portion of the RBs in the plurality of RBs being different from the first portion of the RBs in the plurality of RBs,
• wherein the second DMRS sequence is different from the first DMRS sequence,
• wherein the first DMRS sequence is based on a first root sequence used for the first portion of the plurality of RBs that are overlapping,
• wherein the second DMRS sequence is based on a second root sequence used for the second portion of the plurality of RBs that are non-overlapping, and
• wherein the second root sequence is independent from the first root sequence.

An apparatus of a user equipment (UE), comprising:

• one or more processors configured to:
• obtain an uplink grant for a plurality of resource blocks (RBs), the uplink grant indicating that use of multiple demodulation reference signals (DMRS) sequences is enabled;
• identify a first cluster of the plurality of RBs that are overlapping with a set of RBs granted to a second UE;
• identify a second cluster of the plurality of RBs that are non-overlapping with the set of RBs granted to the second UE;
• generate a first demodulation reference signal (DMRS) sequence for the first cluster of the plurality of RBs;
• generate a second DMRS sequence for the second cluster of the plurality of RBs, the second DMRS sequence being different from the first DMRS sequence;
• and
• generate an uplink transmission, the uplink transmission having the first DMRS sequence for the first cluster of the plurality of RBs and having the second DMRS sequence for the second cluster of the plurality of RBs,
• wherein the first DMRS sequence is based on a first Zadoff-Chu root sequence used for the first cluster of the plurality of RBs that are overlapping,
• wherein the second DMRS sequence is based on a second Zadoff-Chu root sequence used for the second cluster of the plurality of RBs that are non-overlapping, and
• wherein the second Zadoff-Chu root sequence is independent from the first Zadoff-Chu root sequence.

A method for wireless communication, comprising:

• obtaining an uplink grant for a plurality of resource blocks (RBs);
• determining a first portion of the plurality of RBs that are overlapping with a set of RBs granted to a second UE;
• determining a second portion of the plurality of RBs that are non-overlapping with the set of RBs granted to the second UE;
• generating a first demodulation reference signal (DMRS) sequence for the first portion of the plurality of RBs;
• and
• generating a second DMRS sequence for the second portion of the plurality of RBs,
• wherein the second DMRS sequence is different from the first DMRS sequence,
• wherein the first DMRS sequence is based on a first root sequence used for the first portion of the plurality of RBs that are overlapping,
• wherein the second DMRS sequence is based on a second root sequence used for the second portion of the plurality of RBs that are non-overlapping, and
• wherein the second root sequence is independent from the first root sequence.