White Space Spectrum Reassignment for LTE Secondary Channels
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Solution Overview
Problem
In communication systems, the arrival of primary users in white spaces often leads to inefficient use of frequency spectrum, as secondary users are forced to switch to new bands or use licensed spectrum, leaving unused resources unused, especially in areas with varying population density and broadcast station presence.
Innovation Solution
A method and apparatus for efficiently reassigning secondary communication channels to unused portions of white spaces by reconfiguring them into non-contiguous or reduced bandwidth channels, using a frequency reassignment circuit with a filter array and routing logic to selectively route signals and avoid primary user frequencies, allowing continuous data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary users switch to new bands or licensed spectrum when primary users arrive in white spaces, then interference with primary users is avoided, but frequency spectrum utilization efficiency deteriorates
Solution Approach 1:
The patent segments the frequency spectrum into multiple sub-channels or frequency blocks within the white space. When primary users arrive, the system divides the available spectrum and allocates specific segments to secondary users, allowing simultaneous operation without interference. This segmentation enables continuous spectrum utilization even when primary users are present.
Solution Approach 2:
The patent implements dynamic frequency assignment where secondary users can dynamically switch between different frequency blocks within the white space based on primary user activity. When primary users arrive in certain frequency ranges, secondary users dynamically migrate to other available blocks within the same white space, maintaining continuous operation without leaving the white space entirely.
2Reliability
If secondary users leave white spaces when primary users arrive, then interference is avoided, but loss of unused spectrum resources increases
Solution Approach 1:
The patent converts the presence of primary users (which would normally force secondary users to leave) into an opportunity for dynamic spectrum sharing. By implementing intra-white-space frequency reassignment, the system allows secondary users to adapt to primary user presence and continue utilizing the white space resources, effectively converting the harmful effect of primary user arrival into a manageable condition that maintains spectrum utilization.
3Productivity
If contiguous secondary communication channels are reassigned to non-contiguous channels, then spectrum utilization improves, but device complexity increases
Solution Approach 1:
The patent introduces a frequency reassignment circuit as an intermediary component that handles the complex task of frequency translation and channel reassignment. This dedicated circuitry manages the mapping between contiguous and non-contiguous channels, isolating the complexity from the main communication system and enabling efficient spectrum utilization through specialized hardware designed for this specific function.
Data Source
AI summary
One embodiment of the present invention relates to a method for efficient reassignment of a secondary communication channel (having a first priority) within a white space, upon arrival of a conflicting primary user signal (having a second priority higher than the first priority). In particular, the method comprises reassigning a secondary communication channel to unused portions of one or more white spaces remaining after the arrival of one or more primary users. For example, in one embodiment wherein one or more secondary communication channels are operated at contiguous secondary frequency ranges within a white space, a primary/incumbent user may arrive at a frequency range that conflicts with the secondary frequency range and that generates unused frequency portions of the white space(s). The secondary communication channel may be reassigned to the unused frequency portions of the white space (e.g., forming a non-contiguous secondary communication channel, forming a secondary communication channel having a reduced bandwidth).