Multi-Carrier Receiver Frequency Error Compensation
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Solution Overview
Problem
In dual cell HSDPA operations, existing technologies face challenges in accurately compensating for frequency errors between carriers, leading to inefficiencies and increased complexity, especially when using separate local oscillators for each carrier, which adds cost and complexity.
Innovation Solution
A wireless receiver design that utilizes a single analog oscillator for down-converting multi-carrier signals, with coarse frequency correction applied to the analog oscillator and fine frequency corrections applied in the digital domain using digital oscillators to separate and adjust the carrier signals, allowing for efficient frequency error compensation between carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate local oscillators are used for each carrier, then frequency error compensation for each carrier is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple carrier processing functions into a single receiver chain. Multiple carriers are down-converted using a common local oscillator and processed through a single digital signal processing path, eliminating the need for separate oscillators and receiver paths for each carrier. This merging approach reduces device complexity while maintaining frequency error compensation capability through digital processing.
Solution Approach 2:
The patent replaces the mechanical/analog approach of using separate local oscillators for each carrier with a digital signal processing approach. Frequency error compensation is achieved through digital mixing and processing in the baseband, substituting the need for multiple precision analog oscillators with a single oscillator and digital correction algorithms.
2Measurement precision
If separate local oscillators are used for each carrier, then frequency error compensation for each carrier is improved, but cost increases
Solution Approach 1:
The patent merges multiple carrier processing functions into a single receiver chain, reducing the bill of materials by eliminating redundant oscillators and associated circuitry. This consolidation directly reduces manufacturing cost while maintaining the required frequency error compensation performance through shared hardware resources and digital processing.
3Device complexity
If a single local oscillator is used to down-convert both carrier signals, then device complexity and cost are reduced, but frequency error compensation capability deteriorates
Solution Approach 1:
The patent replaces the need for multiple analog oscillators with a single analog oscillator combined with digital signal processing. Frequency error compensation is achieved through digital mixing operations in the baseband, where complex exponential sequences are used to correct frequency offsets. This substitution of analog precision requirements with digital processing maintains compensation accuracy while reducing hardware complexity.
Solution Approach 2:
The patent changes the domain in which frequency error compensation is performed, moving from analog frequency domain (requiring precise oscillators) to digital baseband domain. By performing frequency correction as a digital parameter adjustment rather than an analog frequency adjustment, the system achieves the same compensation accuracy with lower hardware requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient frequency error compensation between carriers, reducing complexity and cost while maintaining high performance, applicable in both UE and base stations, and supports dual-cell HSDPA and LTE standards.
Implementation Method 1
down-converted by mixing each with the output of a common analog oscillator
Implementation Method 2
low-pass filtering to remove signal components outside the desired frequency range
Data Source
AI summary
A wireless receiver utilizes a single analog oscillator to down-convert multi-carrier signals in one or more receiver front-end paths. The received signals are digitized, and the different carrier signals received at each antenna are separated in digital domain by mixing the digitized signal from each antenna with a carrier/antenna separation digital oscillator to down-convert a desired carrier signal and low-pass filtering to remove unwanted carriers. A coarse frequency correction adjusts the analog oscillator, and fine frequency corrections adjust digital oscillators mixing with the separated signals. In one embodiment, the fine frequency correction is applied to the carrier/antenna separation digital oscillators in the separation function. In another embodiment, the fine frequency correction is applied to frequency adjustment digital oscillators mixing with the separated signals. The frequency corrections may be based on reference symbols in the received signals.