MIMO Reference Signal Design for Legacy LTE-A Compatibility
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Solution Overview
Problem
Cellular network providers face challenges in supporting both legacy Rel-8 and LTE-A systems, particularly in efficiently transmitting reference signals that are compatible with both standards, especially when dealing with high-order MIMO and the need for backwards compatibility.
Innovation Solution
A method and transmitter design that define specific resource blocks for reference signals in a matrix, allowing for the simultaneous transmission of legacy and next-generation standard-compliant signals using a combination of time-division and frequency-division multiplexing techniques, ensuring compatibility and minimizing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single transmitting terminal codes transmissions according to the known system compliance of mobile terminals, then transmission efficiency for that specific terminal is improved, but the complexity of supporting both legacy Rel-8 and LTE-A systems increases considerably
Solution Approach 1:
The patent segments the reference signal resources in the time-frequency grid by assigning different resource blocks to legacy Rel-8 terminals and LTE-A terminals. This segmentation allows the transmitting terminal to serve both terminal types simultaneously without requiring complex per-terminal coding, as each terminal type receives reference signals designed for its specific MIMO order requirements.
Solution Approach 2:
The patent creates a universal reference signal allocation scheme that works for both legacy and next-generation terminals. By defining a unified resource block structure where both Rel-8 and LTE-A terminals can be served using the same physical infrastructure and signal formats, the system achieves multi-functionality without proportionally increasing complexity.
2Ease of operation
If considerable overhead is introduced to distinguish between legacy system and new system transmissions, then system differentiation and management are improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent applies local quality by assigning reference signals with specific properties to specific resource block locations based on the terminal type. Legacy terminals receive reference signals at locations defined by the Rel-8 standard, while LTE-A terminals receive reference signals at other designated locations. This localized differentiation allows clear system management without requiring pervasive overhead throughout the entire transmission.
Solution Approach 2:
The patent resolves the contradiction by moving the differentiation mechanism from the time domain or frequency domain alone to a combined time-frequency resource block allocation. By utilizing the two-dimensional resource grid and assigning different reference signal patterns across both dimensions, the system achieves clear terminal type differentiation while minimizing the total overhead proportion.
3Adaptability or versatility
If high-order MIMO reference signal design is implemented, then support for LTE-A terminals is improved, but backwards compatibility with legacy Rel-8 terminals deteriorates
Solution Approach 1:
The patent segments the reference signal resource allocation to provide dedicated resource blocks for high-order MIMO operations to LTE-A terminals while maintaining separate resource blocks with legacy-compatible reference signal designs for Rel-8 terminals. This segmentation allows the system to implement advanced features for next-generation terminals without disrupting legacy terminal operations.
Solution Approach 2:
The patent applies local quality by implementing high-order MIMO reference signal characteristics only in specific resource block locations allocated to LTE-A terminals, while maintaining traditional reference signal properties in locations allocated to legacy terminals. This localized implementation ensures that LTE-A terminals receive the enhanced functionality they require while legacy terminals continue to operate with familiar signal characteristics.
Data Source
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AI summary
In a cellular network supporting both legacy standard-compliant mobile terminals and next generation standard-compliant mobile terminals, both legacy reference signals and next generation reference signals are supported. A method of operation of a MIMO transmitter compliant with both standards includes: defining a matrix of resource blocks within an information channel of the cellular network, wherein each resource block corresponds to a region of subcarriers of a transmission timeslot at a given frequency subband; assigning a first set of reference signals (RSs) for the legacy standard-compliant mobile terminals to resource blocks at specific locations within the matrix to be transmitted by the MIMO transmitter, the specific locations being defined by the legacy standard; and assigning a second set of RSs for the next-generation standard-compliant mobile terminals to other resource blocks within the matrix to be transmitted by the MIMO transmitter.