LTE Uplink SRS Frequency-Hop Pattern Determination
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Solution Overview
Problem
In LTE wireless communication systems, especially in TDD mode, it is challenging for user equipment (UE) to guarantee uniform frequency-hop patterns and sound the entire system bandwidth due to inconsistent allocation of uplink sub-frames, leading to incomplete bandwidth coverage and non-uniform frequency-hop patterns.
Innovation Solution
A method for determining a continuous frequency-hop parameter nSRS, which involves generating an SRS sequence and mapping it to physical resource elements using RRC signaling, ensuring that the UE can sound the entire frequency-hop bandwidth by adjusting the frequency-hop pattern based on the radio frame index, time slot index, and SRS period, thereby avoiding collisions and ensuring uniform distribution across different configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the last symbol in some sub-frames is used to transmit SRS in LTE TDD system, then uplink SRS transmission can be performed, but uniform frequency-hop patterns and complete bandwidth coverage cannot be guaranteed due to inconsistent uplink sub-frame allocation
Solution Approach 1:
The patent changes the parameter used for frequency-hop pattern determination from sub-frame index to radio frame index. This parameter change ensures that the frequency-hop pattern remains consistent and uniform across different TDD configurations, as radio frame allocation is more consistent than sub-frame allocation in TDD systems.
Solution Approach 2:
The patent segments the frequency-hop pattern determination into two parts: the first N bits from the radio frame index determine the base frequency position, and the remaining bits determine the offset within the allocated bandwidth. This segmentation allows for both uniform distribution and flexible bandwidth adaptation.
2Adaptability or versatility
If 8-bit RRC signaling is used to assign frequency-hop schemes, then four different system bandwidth configurations can be supported, but only partial bandwidth coverage is achieved in TDD mode
Solution Approach 1:
The patent introduces a new dimension for frequency-hop pattern determination by using radio frame index instead of sub-frame index. This dimensional change allows the system to achieve complete bandwidth coverage in TDD mode while maintaining support for four different system bandwidth configurations through the existing 8-bit RRC signaling structure.
3Productivity
If sub-frame index is used for frequency-hop calculation, then frequency allocation can be done per sub-frame, but collision avoidance and uniform distribution cannot be achieved in TDD configurations
Solution Approach 1:
The patent introduces radio frame index as an intermediary between the time domain structure and frequency-hop pattern determination. This intermediary ensures uniform distribution and collision avoidance by providing a consistent reference that is not affected by the variable uplink sub-frame allocation in different TDD configurations.
Data Source
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AI summary
A method for transmitting an uplink sounding reference signal includes indexing Single Carrier Frequency Division Multiple Access (SC-FDMA)symbols within a single radio frame for transmitting a Sounding Reference Signal (SRS) as a number k, and calculating a value of nSRS according to number k and an index number of the radio frames for transmitting the SRS, determining an index number of a frequency-domain start sub-carrier mapped from time-domain SRS symbol with nSRS, and transmitting the SRS through the sub-carrier with the determined index number determined. Before transmitting the SRS, the start frequency position for SRS should be changed according to the specific frequency-hop pattern to guarantee that the UE may uniformly sound the entire SRS frequency-hop bandwidth after multiple soundings.