DMRS Port Mapping for Orthogonal Resource Allocation
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing demodulation reference signal (DMRS) resource allocation, particularly in multiple-access technologies like LTE and NR, which can lead to suboptimal performance due to improper handling of orthogonal DMRS ports and frequency domain orthogonal cover codes (FD-OCC).
Innovation Solution
The proposed solution involves transmitting DMRS capability information to restrict resource allocation for physical channels to multiples of two orthogonal DMRS ports, ensuring they are not multiplexed in the same code division multiplexing group, and applying FD-OCC to every three or six resource elements of the DMRS, thereby optimizing DMRS port management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DMRS ports are multiplexed in the same CDM group with different FD-OCC lengths, then resource utilization increases, but port orthogonality deteriorates
Solution Approach 1:
The patent applies different FD-OCC lengths (length-2 vs length-4) to different DMRS ports within the same CDM group, creating local differentiation in code properties. This allows ports to be multiplexed while maintaining orthogonality through localized code design rather than uniform code allocation.
Solution Approach 2:
The patent changes the FD-OCC length parameter for different DMRS ports (from uniform length to variable lengths of 2 and 4). This parameter variation enables simultaneous multiplexing of multiple ports while preserving orthogonality, resolving the contradiction between resource utilization and port orthogonality.
2Reliability
If resource allocation is restricted to integer multiples of resource blocks, then DMRS port orthogonality is maintained, but spectral efficiency decreases
Solution Approach 1:
The patent changes the resource allocation parameter from continuous to discrete integer multiples of resource blocks. This discretization maintains orthogonality by ensuring proper alignment of DMRS ports while the patent compensates for spectral efficiency through optimized FD-OCC application within these constrained blocks.
Solution Approach 2:
The patent applies FD-OCC locally within each resource block allocation, ensuring that orthogonality is maintained at the local block level while allowing flexible overall resource allocation. This local application of codes preserves orthogonality without requiring overly conservative system-wide resource restrictions.
3Reliability
If VRB-to-PRB interleaving is applied, then frequency diversity is improved, but DMRS resource allocation complexity increases
Solution Approach 1:
The patent applies FD-OCC to DMRS ports before the VRB-to-PRB interleaving mapping process. This preliminary code application ensures that orthogonality is established in advance, simplifying the subsequent interleaving operation and reducing overall allocation complexity while maintaining frequency diversity benefits.
Solution Approach 2:
The patent modifies the DMRS resource allocation parameters to work harmoniously with VRB-to-PRB interleaving by applying FD-OCC with specific lengths that are compatible with the interleaving pattern. This parameter adjustment maintains frequency diversity while reducing the computational complexity of the overall allocation process.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a network entity, demodulation reference signal (DMRS) capability information that indicates a number of orthogonal DMRS ports for DMRS communications. The UE may receive, from the network entity, information that is associated with a DMRS port mapping for the number of orthogonal DMRS ports and that indicates to restrict a resource allocation for a physical downlink shared channel (PDSCH) or physical uplink shared channel (PUSCH) to an integer that is a multiple of two for each contiguous physical resource block, to restrict a virtual resource block to physical resource block (VRB-to-PRB) mapping, or to restrict the number of orthogonal DMRS ports such that a legacy number of DMRS ports and an extended number of DMRS ports are not multiplexed in a same code division multiplexing (CDM) group. Numerous other aspects are described.