Full-Duplex Shared Medium Interference Management
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Solution Overview
Problem
Full-duplex communication over shared transmission media, such as coaxial cables, faces challenges with inter-terminal interference due to limited isolation between terminals, which cannot be removed as the interfering signal is not known to the receiving terminal, leading to signal clipping and reduced signal resolution.
Innovation Solution
A method involving a resource controller that characterizes interference between subscriber devices, groups them into interfering groups, and assigns disjoint transmission time intervals to prevent simultaneous upstream and downstream communications within these groups, thereby avoiding harmful interference while maintaining full-duplex transmission capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the dynamic range of receivers is increased to mitigate inter-terminal interference, then signal clipping is avoided, but signal resolution for lower-power useful signal decreases
Solution Approach 1:
The patent segments the cable network into multiple interfering groups based on interference characteristics. Terminals within the same interfering group are separated in time (TDD), while terminals from different interfering groups can communicate simultaneously in full-duplex mode. This segmentation allows the system to manage inter-terminal interference at the group level rather than requiring increased dynamic range across all receivers.
Solution Approach 2:
The patent changes the time-domain parameter by introducing disjoint transmission time intervals for terminals within the same interfering group. Instead of increasing the receiver's dynamic range parameter, the system uses time division to separate interfering signals, thereby maintaining signal resolution while mitigating interference.
2Productivity
If full-duplex communication is implemented over shared transmission medium, then data throughput is doubled, but inter-terminal interference causes signal clipping
Solution Approach 1:
The patent divides terminals into interfering groups and applies time division within each group while maintaining frequency division between groups. This allows simultaneous upstream and downstream communications across different groups, achieving doubled throughput while controlling interference through group-based separation.
Solution Approach 2:
The patent adds a time dimension to the frequency-domain full-duplex communication by implementing TDD within interfering groups. This creates a hybrid FDMA-TDD scheme that achieves full-duplex capacity while using time separation to eliminate harmful interference within groups.
3Adaptability or versatility
If terminals are assigned non-overlapping frequency bands for full-duplex communication, then same carriers can be used for both directions, but limited isolation between terminals causes interference
Solution Approach 1:
The patent segments terminals into interfering groups based on their isolation characteristics. Terminals within the same group are separated in time, while terminals from different groups can operate simultaneously. This segmentation enables full-duplex versatility while managing interference through group-based time division.
Solution Approach 2:
The patent implements dynamic resource allocation where transmission time intervals are assigned based on the communication direction and interfering group membership. The system dynamically switches between TDD for terminals in the same interfering group and simultaneous full-duplex operation for terminals in different groups, optimizing both adaptability and interference management.
Data Source
AI summary
The present invention relates to a method for assigning transmission resources (101) to communications between an access node (11) and a plurality of subscriber devices (41 to 46) coupled to a shared transmission medium.In accordance with an embodiment of the invention, the method comprises characterizing interference between respective ones of the plurality of subscriber devices over the shared transmission medium, grouping highly-interfering subscriber devices into respective interfering groups (G1, G2, G3, G4) based on the so-characterized interference, and assigning disjoint transmission time intervals to upstream communication from any one subscriber device of any one interfering group and to downstream communication towards any other subscriber device of the same interfering group.The present invention also relates to a resource controller.