Channel estimation, throughput and fairness for multi-user, multipleinput, multiple-output (MU-MIMO) systems through dynamic port allocation
A method and system for improving channel estimation for multi-user, multiple-input, multiple-output (MU-MIMO) systems through dynamic DM-RS port allocation in a 5G New Radio network is provided. The method comprises of allocating, by a Scheduler aware UE port allocation unit, one or more MU-MIMO ports to a plurality of code division multiplexing (CDM) groups for a plurality of UE users, performing, by a code selection unit, a code selection based on a number of allocated MU-MIMO ports, determining, by a spreading factor unit, a spreading factor allocated for each of the MU-MIMO ports in each of the plurality of CDM groups, determining, by a signalling unit, a Downlink Control Information (DCI) signalling of a Partial Port Occupancy (P-Poi) transmission for each UE and obtaining, by a channel estimation unit, channel estimates at the receiver through VSFOCC de-spreading based on the P-POI assigned for each of the MU-MIMO ports.
1 . A method for improving channel estimation for multi-user, multiple-input, multiple-output (MU-MIMO) systems through dynamic demodulation reference signal (DM-RS) port allocation in a 5G New Radio network, the method comprising:
allocating, by a Scheduler aware UE port allocation unit, one or more MU MIMO ports to a plurality of code division multiplexing (CDM) groups for a plurality of UE users;
performing, by a code selection unit, a code selection based on a number of MU-MIMO ports allocated to the plurality of CDM groups; where a Code Division Multiplexing (CDM) group is a set of time-frequency resources where MU-MIMO ports are multiplexed using orthogonality of codes;
determining, by a spreading factor unit, a spreading factor allocated for each of the MU-MIMO ports in each of the plurality of CDM groups;
determining, by a signalling unit, a Downlink Control Information (DCI) signalling of a Partial Port Occupancy (P-Poi) transmission for each UE; and
obtaining, by a channel estimation unit, channel estimates at the receiver through variable spreading factor orthogonal cover codes (VSFOCC) de-spreading based on the P-POI assigned for each of the MU-MIMO ports; and
interpolating, by a linear or DFT interpolator, the obtained channel estimates to determine the channel over a number of Physical Resource blocks (N PRB ), wherein the interpolation along with VSFOCC de-spreading increases the performance gain for channels.
2 . The method of claim 1 , wherein the Scheduling aware UE port mapping unit allots a plurality of spreading factors for the plurality of UE users based on a Modulation and Coding Scheme (MCS) information from a schedule unit.
3 . The method of claim 1 , wherein the code selection for each MU-MIMO port scheduled in the CDM group is assigned from an Orthogonal Variable Spreading Factor (OVSF tree) structure, where each MU-MIMO port present in a same CDM group are mapped to unique Orthogonal Cover Codes (OCC).
4 . The method of claim 1 , further comprising combining, by the channel estimator unit, least square estimation, and P-Poi information based de-spreading of the plurality of CDM groups to perform channel estimation.
5 . The method of claim 1 , further comprising:
reducing an interpolation error of the channel estimates by increasing a number of unique channel estimates for partially loaded COM groups through VSFOCC de-spreading.
6 . A multi-user, multiple-input, multiple-output (MU-MIMO) system to improve channel estimation in 5G New Radio Network, the system comprises:
a transmitter comprising:
a Scheduler aware UE port allocation unit to allocate one or more MU-MIMO ports to a plurality of code division multiplexing (CDM) groups for a plurality of UE users;
a code selection unit to perform code selection according to a number of MU-MIMO ports assigned in the plurality of CDM groups, where a Code Division Multiplexing (CDM) group is a set of time-frequency resources where MU-MIMO ports are multiplexed using orthogonality of codes;
a scheduler aware UE port mapping unit to allot a reduced de-spreading factor for the users based on the Modulation and Coding Scheme (MCS) and a total number of scheduled user information received from the Scheduler aware UE port allocation unit; and
a spreading factor unit to determine the spreading factor for the allocated one or more MU-MIMO ports in each of the plurality of CDM groups;
a signalling unit to transmit Downlink Control Information (DCI) signalling of a Partial Port Occupancy (P-Poi) information for each User Equipment; and
a receiver comprising:
a channel estimator unit to perform channel estimation with variable spreading factor orthogonal cover codes (VSFOCC) de-spreading based on a Partial Port Occupancy (P-Poi) assigned for each of the MU-MIMO ports; and
an interpolator to interpolate the obtained channel estimates over a number of Physical Resource blocks, (N PRB ), wherein the interpolator is one of a linear or DFT interpolator, where interpolation along with VSFOCC de-spreading increases performance gain for channels.
7 . The system of claim 6 , wherein the Scheduling aware UE port mapping unit allots a plurality of spreading factors for the plurality of UE users based on a Modulation and Coding Scheme (MCS) information from a schedule unit.
8 . The system of claim 6 , wherein the code selection for each MU-MIMO port scheduled in the COM group is assigned from an Orthogonal Variable Spreading Factor (OVSF tree) structure, where each MU-MIMO port present in a same CDM group are mapped to unique Orthogonal Cover Codes (OCC).
9 . The system of claim 6 , wherein the channel estimator unit further combines a least square estimation and P-Poi information based de-spreading of the plurality of CDM groups to perform channel estimation.
10 . The system of claim 6 , wherein the interpolator is configured to reduce an interpolation error of the channel estimates by increasing a number of distinct channel estimates for partially loaded CDM groups through VSFOCC de-spreading.