User Equipment Bandwidth Adjustment for Local Oscillator Leakage Avoidance
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Solution Overview
Problem
In multicarrier radio communication systems, user equipment (UE) face challenges in monitoring the whole system bandwidth due to local oscillator leakage, which affects data demodulation and control signaling, especially when the centre frequency coincides with critical subcarriers, limiting scheduling flexibility and requiring costly receiver circuitry to suppress interference.
Innovation Solution
The UE adjusts its bandwidth to correspond to a determined subset of subcarriers and fine-tunes its local oscillator to ensure the centre frequency does not coincide with predetermined subcarriers, allowing it to monitor a sub-bandwidth anywhere within the system bandwidth and avoid critical information loss, while reducing the need to suppress local oscillator leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the UE monitors the whole system bandwidth, then the UE can receive all information, but local oscillator leakage causes interference on critical subcarriers especially at the centre frequency
Solution Approach 1:
The patent divides the system bandwidth into multiple sub-bandwidths and allows the UE to monitor only a selected sub-bandwidth rather than the entire bandwidth. This segmentation approach reduces the impact of local oscillator leakage by limiting the UE's reception bandwidth to a portion where interference is minimized, while still enabling sufficient communication functionality.
Solution Approach 2:
The patent enables dynamic adjustment of the UE's reception bandwidth parameter and centre frequency. By changing these parameters, the UE can select optimal bandwidth and frequency positions that avoid critical subcarriers affected by local oscillator leakage, while maintaining adequate information reception capability.
2Object-affected harmful factors
If the UE uses receiver circuitry to suppress local oscillator leakage, then interference is reduced, but the cost of receiver circuitry increases
Solution Approach 1:
The patent extracts the problematic centre frequency region from the UE's reception bandwidth. By selecting a sub-bandwidth that excludes or minimizes inclusion of the centre frequency where local oscillator leakage occurs, the patent eliminates the need for expensive suppression circuitry while still maintaining adequate communication performance.
Solution Approach 2:
Instead of investing in expensive receiver circuitry to suppress local oscillator leakage, the patent adopts a simpler approach: the UE uses a relatively narrow and flexible reception bandwidth that naturally avoids the problematic frequency region. This 'disposable' bandwidth allocation strategy is cheaper than implementing robust interference suppression hardware.
3Object-affected harmful factors
If the UE is limited to monitor bandwidth symmetrically around the DC subcarrier, then local oscillator interference is minimized, but scheduling flexibility is reduced
Solution Approach 1:
The patent introduces dynamic bandwidth selection where the UE can be assigned different sub-bandwidths and frequency positions based on scheduling decisions. Rather than being fixed to a symmetric bandwidth around DC, the UE's reception parameters can be dynamically adjusted to optimize both interference avoidance and scheduling flexibility according to current system conditions.
Solution Approach 2:
The patent applies local quality by allowing different parts of the frequency spectrum to have different reception characteristics. The UE's reception bandwidth is selectively positioned to include or exclude specific frequency regions with different interference characteristics, enabling optimized performance for each local frequency region rather than uniform treatment across the entire bandwidth.
4Productivity
If the centre frequency of local oscillator coincides with a predetermined subcarrier, then the subcarrier can be used for transmission, but critical information loss occurs due to interference
Solution Approach 1:
The patent takes preliminary action by pre-identifying and excluding the centre frequency region from the UE's reception bandwidth before any transmission occurs. By proactively selecting a sub-bandwidth that avoids the problematic centre frequency where local oscillator leakage occurs, the patent prevents critical information loss on predetermined subcarriers rather than attempting to correct interference after it occurs.
Data Source
AI summary
A User Equipment, UE, supporting communication in a multicarrier radio communication system and a method therein for receiving information from a Radio Base Station, RBS, are provided. The method comprises determining 310 a bandwidth by which the UE will receive information, the bandwidth comprising a plurality of sub-carriers. The method also comprises adjusting 320 a bandwidth of the UE to correspond to the determined bandwidth by which the UE will receive information; and fine tuning 330 a local oscillator of the UE such that a centre frequency of a local oscillator does not coincide with a predetermined subcarrier transmitted from the RBS.