SRS Partial Sounding for Higher Port Multiplexing and Coverage
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Solution Overview
Problem
Current NR systems face challenges with SRS capacity and coverage, particularly due to the minimum configurable SRS bandwidth being 4 RBs per OFDM symbol, limiting the number of SRS ports that can be multiplexed and affecting uplink coverage.
Innovation Solution
Implementing SRS partial sounding, allowing the UE to transmit SRS in a fraction of the configured bandwidth, with two types: Type 1 where the same part is sounded in every OFDM symbol and Type 2 where the sounded part varies over time, enhancing SRS capacity by increasing the number of multiplexed ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the minimum configurable SRS bandwidth is set to 4 RBs per OFDM symbol, then the SRS transmission is simplified and standardized, but the number of SRS ports that can be multiplexed is limited and uplink coverage is affected
Solution Approach 1:
The patent introduces partial sounding by segmenting the configured SRS bandwidth into a fractional portion that is actually transmitted. The SRS bandwidth is divided such that only a fraction (e.g., 1/2, 1/4) of the total bandwidth is sounded at a time, while the remaining portions are sounded in subsequent OFDM symbols. This segmentation allows more SRS ports to be multiplexed across multiple symbols without increasing the per-symbol bandwidth requirement, thereby resolving the contradiction between configuration simplicity and multiplexing capacity.
Solution Approach 2:
The patent extends the SRS transmission from a single OFDM symbol to multiple OFDM symbols in the time domain. By utilizing the time dimension, the system can sound multiple fractional portions of the bandwidth across different symbols, effectively increasing the total number of multiplexed ports without violating the minimum bandwidth constraint per symbol. This dimensional transition from space-only (frequency) to space-time (frequency-time) resolves the contradiction.
2Ease of operation
If the same part of bandwidth is sounded in every OFDM symbol (Type 1 partial sounding), then the implementation is simpler and coverage is improved, but the number of multiplexed ports is limited compared to Type 2
Solution Approach 1:
The patent provides two dynamic configurations for partial sounding: Type 1 where the same fractional portion is reused across symbols (static pattern), and Type 2 where different fractional portions are sounded in different symbols (dynamic pattern). Type 2 allows for more flexible port multiplexing by dynamically switching between different frequency portions, thereby achieving higher multiplexing capacity while maintaining implementation simplicity through standardized control mechanisms.
3Quantity of substance
If partial sounding is implemented to increase multiplexed ports, then SRS capacity is improved, but the time required to sound the entire bandwidth increases
Solution Approach 1:
The patent implements partial sounding where the fractional portion of bandwidth is sounded continuously across multiple OFDM symbols. Instead of leaving gaps or idle time between sounding different portions, the system maintains continuous SRS transmission by overlapping the time required to sound multiple portions. This continuous action allows the entire bandwidth to be sounded efficiently across multiple symbols without significant time penalty, resolving the contradiction between multiplexing capacity and time consumption.
Data Source
AI summary
According to some embodiments, a method performed by a wireless device comprising receiving a sounding reference signal (SRS) configuration comprising an indication of a size of a fractional portion of an SRS bandwidth and a location of the fractional portion of the SRS bandwidth to use for sounding and transmitting SRS according to the received SRS configuration.