Uplink Reference Signal Multiplexing via RSMB Partitioning
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Solution Overview
Problem
Current communication systems face challenges in efficiently multiplexing uplink reference signals and partitioning scheduling bandwidths, particularly in DFT-spread OFDMA systems, which affects channel quality estimation and data signal transmission scheduling.
Innovation Solution
The method involves multiplexing reference signals with a transmission bandwidth larger than data signals in sub-frames, using distributed and localized RS transmissions, and dividing the system bandwidth into smaller Reference Signal Multiplexing Blocks (RSMBs) to enable efficient scheduling and channel quality estimation, allowing for joint or independent scheduling of data and reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals are transmitted with larger bandwidth than data signals (distributed RS), then channel quality estimation accuracy is improved, but spectrum efficiency deteriorates due to wider bandwidth occupation
Solution Approach 1:
The system divides the uplink transmission into separate short blocks (SB) for reference signals and long blocks (LB) for data. Reference signals are confined to SB while data transmission occupies LB, separating the functions of channel estimation and data transmission into distinct time-frequency resources.
Solution Approach 2:
The reference signal bandwidth is made dynamic by allowing UEs to transmit distributed RS (occupying larger bandwidth) in some sub-frames and localized RS (occupying smaller bandwidth) in others, based on scheduling decisions and channel conditions, optimizing the trade-off between estimation accuracy and spectrum efficiency.
2Object-generated harmful factors
If reference signals are confined to short blocks only, then interference to data transmission is reduced, but channel estimation flexibility deteriorates
Solution Approach 1:
Different parts of the uplink structure are assigned different qualities/functions: short blocks (SB) are dedicated to reference signal transmission with high quality requirements for channel estimation, while long blocks (LB) are optimized for data transmission. This local differentiation allows RS to be confined to SB without compromising overall system performance.
3Loss of information
If distributed RS transmission is used, then channel sounding capability is improved, but device complexity increases due to more complex signal processing
Solution Approach 1:
Distributed reference signal transmission is performed periodically in certain sub-frames rather than continuously. The network can schedule distributed RS transmissions at specific intervals to obtain channel sounding information when needed, while using localized RS in other sub-frames to reduce processing complexity during normal operation.
Data Source
AI summary
A method for multiplexing reference signal (RS) transmissions from user equipments (UEs), with the RS having a bandwidth larger than the data signal bandwidth (distributed RS) is provided. A transmission time interval (TTI) comprises of one or more sub-frames and each sub-frame comprises of at least two RS transmission periods and a plurality of data signal transmission periods. A distributed RS is transmitted during at least one of the at least two RS transmission periods in at least one of the sub-frames comprising the TTI. During the remaining RS transmission periods, for a UE having a data signal transmission, the RS bandwidth is substantially the same as the data signal bandwidth (localized RS). The total system bandwidth is divided into contiguous, non-overlapping sub-bandwidths, called reference signal multiplexing blocks (RSMBs). Transmission of distributed RS occurs within an RSMB and does not cross over different RSMBs. The size and number of RSMBs can be re-configurable in time and a re-configuration period is much larger than the TTI duration.