Secondary System Transceiver Interference Protection
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Solution Overview
Problem
In wireless broadcast systems, secondary systems face interference issues when sharing spectrum with primary systems, particularly due to proximity of transmitters to receivers, leading to impractical reuse of unused channels by secondary systems, as primary receivers are not designed to handle strong adjacent signals and interference prevention requires physical separation, which is often unfeasible.
Innovation Solution
A method where a secondary system transceiver receives and re-transmits a delayed version of the primary system signal, adjusting power and coding secondary signals to minimize interference, allowing secondary systems to use primary system channels without degrading primary system reception, by synchronizing symbol rates and locking carrier phases to the re-transmitted primary signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If secondary system transmitters are located close to primary system receivers to enable spectrum sharing, then channel utilization efficiency is improved, but interference to primary system receivers increases
Solution Approach 1:
The patent introduces an intermediary mechanism where the secondary system transceiver receives and re-transmits a delayed version of the primary system signal. This delayed re-transmission acts as an intermediary signal that helps primary receivers distinguish and reject the direct strong interference from secondary transmitters, thereby enabling close proximity deployment while protecting primary reception
Solution Approach 2:
The patent changes the timing parameter by introducing a controlled delay to the re-transmitted primary signal. This delay parameter is specifically designed to fall within the multipath delay resolution capability of primary receivers, transforming the interference scenario into a manageable signal structure that receivers can handle
2Reliability
If physical separation is increased between secondary system transmitters and primary system receivers to prevent interference, then signal-to-interference ratio is improved, but coverage area and channel reuse flexibility deteriorate
Solution Approach 1:
The patent makes the system dynamic by allowing secondary systems to adaptively adjust their transmission parameters based on the delayed primary signal. The secondary system can dynamically code its signals using knowledge of the primary signal and adjust power levels, enabling reliable operation without fixed physical separation requirements
3Object-affected harmful factors
If guard channels are left between occupied channels to prevent adjacent channel interference, then interference protection is improved, but spectrum efficiency deteriorates
Solution Approach 1:
The patent converts the potentially harmful adjacent channel interference into a beneficial structure by having the secondary system re-transmit the primary signal on adjacent channels with a controlled delay. This transforms what would be interference into a structured signal that primary receivers can resolve, eliminating the need for guard channels
Data Source
AI summary
A method and transceiver in a secondary system for utilizing channel bandwidths allocated to a primary system. A secondary system transceiver receives a primary system signal, re-transmits a delayed version of the primary system signal, and communicates with secondary system equipment utilizing secondary system signals within at least part of a bandwidth of at least one channel of the primary system. The re-transmission of the primary system signal allows the use of primary system channels by the secondary system without adversely affecting the primary or secondary system users.