Frequency-Selective SRS Precoding for PUSCH Resource Allocation
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Solution Overview
Problem
In wireless communication systems, particularly in 3GPP New Radio (NR) networks, there is a challenge in determining the appropriate precoding for Physical Uplink Shared Channel (PUSCH) transmissions when the SRS resource allocation and PUSCH resource allocation do not span the same Physical Resource Blocks (PRBs, and for UEs that only support non-coherent transmission, frequency-selective precoding and precoded SRS are unclear.
Innovation Solution
The method involves transmitting an SRS on a first set of frequency-domain resources and receiving an uplink scheduling assignment for a second set of frequency-domain resources, where the same precoding applied to the SRS is used for PRBs within the first set, and a different precoding is applied for PRBs outside the first set, based on the closest SRS resource to minimize the absolute distance in resource index, ensuring proper precoding for PUSCH transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency-selective precoding is applied to SRS transmission, then precoding accuracy for PUSCH is improved, but device complexity increases for UEs that only support non-coherent transmission
Solution Approach 1:
The SRS frequency bandwidth is divided into multiple subbands, with each subband using a separate precoder. This segmentation allows frequency-selective precoding to be applied in a manageable way, where each subband can be processed independently rather than requiring complex full-bandwidth frequency-selective precoding
Solution Approach 2:
Different precoding strategies are applied to different subbands based on local channel conditions. Each subband can have its own precoding configuration optimized for that specific frequency range, rather than applying a single precoding strategy across the entire bandwidth
2Productivity
If SRS resource allocation spans different PRBs than PUSCH resource allocation, then frequency resource utilization is improved, but precoding determination becomes ambiguous
Solution Approach 1:
The network introduces intermediate parameters (SRI, TPMI, TRI) that mediate between SRS resource allocation and PUSCH resource allocation. These intermediaries carry precoding information that bridges the gap when SRS and PUSCH occupy different frequency resources, allowing the UE to determine appropriate precoding without direct one-to-one resource mapping
Solution Approach 2:
The network预先 configures multiple SRS resources with different frequency allocations and precoding settings. The UE is instructed to use specific pre-configured SRS resources for channel sounding before PUSCH transmission, allowing precoding to be determined in advance based on the relationship between pre-configured SRS resources and the actual PUSCH allocation
Data Source
AI summary
Systems and methods relating to frequency-selective Sounding Reference Signal (SRS) precoding and uplink transmission are disclosed. In some embodiments, a method of operation of a wireless device comprises transmitting SRS on a first set of frequency-domain resources, and receiving an uplink scheduling assignment for an uplink physical channel comprising a resource allocation of a second set of frequency-domain resources comprising: (a) one or more frequency-domain resources that are also included in the first set and (b) one or more frequency-domain resources that are not included in the first set. In order to form a precoded uplink channel, the method further comprises: for each frequency-domain resource in (a), applying a same precoding as applied to the SRS on the frequency-domain resource; and, for each frequency-domain resource in (b), applying a same precoding as applied to the SRS on a different frequency-domain resource. The method further comprises transmitting the precoded uplink channel.