Uplink SRS Cyclic-Shift Multiplexing for Multi-Antenna Resources
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Solution Overview
Problem
Existing LTE wireless communication systems face challenges in efficiently managing sounding reference signals (SRS) for multiple antennas, particularly in LTE-Advanced, where increased SRS overhead and resource limitations hinder effective SRS transmission.
Innovation Solution
Methods for configuring and transmitting SRS include determining cyclic shift multiplexing and transmission combs for multiple antennas, handling collisions with other channels, and providing triggers for aperiodic SRS transmission, ensuring efficient resource allocation in time, frequency, and code domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SRS transmissions are increased to support multiple antennas in LTE-Advanced, then measurement capability is improved, but SRS overhead increases
Solution Approach 1:
The patent combines SRS transmissions from multiple antennas into the same time-frequency resources by using different cyclic shifts for code division multiplexing. This allows multiple antennas to share the same SRS resources simultaneously, improving measurement capability while avoiding the need for separate dedicated resources for each antenna, thus controlling overhead.
Solution Approach 2:
The patent introduces cyclic shift as an additional dimension for multiplexing SRS transmissions. Instead of allocating separate time-frequency resources for each antenna, the system uses the code domain (cyclic shifts) as another dimension to differentiate between antennas, enabling efficient resource utilization and reduced overhead.
2Measurement precision
If SRS resources are allocated for all antennas, then measurement accuracy is improved, but available resources are insufficient
Solution Approach 1:
The patent merges SRS resources from multiple antennas by allowing simultaneous transmissions in the same time-frequency resources. Through cyclic shift multiplexing, the system combines what would otherwise be separate resource allocations into shared resources, effectively doubling or quadrupling the measurement capability without proportionally increasing total resource consumption.
3Productivity
If cyclic shift multiplexing is used for multiple antennas, then resource efficiency is improved, but interference management becomes more complex
Solution Approach 1:
The patent uses cyclic shift as a configurable parameter to differentiate between antennas. By changing the cyclic shift parameter for each antenna, the system enables simple code division multiplexing that improves resource efficiency. The interference management is handled through standardized procedures that select appropriate cyclic shifts, keeping the complexity manageable despite the improved efficiency.
Data Source
AI summary
A wireless transmit/receiver unit (WTRU) is configured to receive sounding reference signal (SRS) configuration information. The SRS configuration information indicates a plurality of SRS configurations and indicates antenna transmission information. The WTRU is configured to receive SRS trigger information. The SRS trigger information comprises an indication to trigger transmission of one of the plurality of SRS configurations. The WTRU is configured to transmit a plurality of SRS associated with the indication in the SRS trigger information and based on the SRS configuration information. At least a first SRS of the plurality of SRS is transmitted over a first antenna port in a first symbol and at least a second SRS of the plurality of SRS is transmitted over a second antenna port in a second symbol.