Full Duplex Sub-band Pattern Coordination for TDD Interference
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Solution Overview
Problem
Dynamic Time Division Duplexing (TDD) networks face challenges in meeting stringent latency and reliability performance due to the exclusive availability of either downlink or uplink transmission at a time, leading to additional payload buffering delays and cross-link interference (CLI).
Innovation Solution
The method involves receiving full duplex sub-band patterns by network equipment in a radio access network (RAN) and associating them with specific categories of uplink and downlink traffic. This allows for scheduling and transmission of traffic according to the full duplex sub-band patterns during TDD timing units, while also determining and mitigating CLI through compression subspace plans and traffic-aware coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic TDD is used to enable flexible resource allocation, then adaptability to asymmetric traffic patterns is improved, but cross-link interference between neighboring nodes increases
Solution Approach 1:
The frequency spectrum is divided into full-duplex sub-bands, allowing independent control of uplink and downlink transmissions within the same time slot. This segmentation enables neighboring nodes to operate in different directions simultaneously without mutual interference, resolving the contradiction between dynamic adaptability and cross-link interference.
Solution Approach 2:
The system dynamically configures full-duplex sub-band patterns based on real-time traffic conditions and node coordination. Neighboring nodes exchange information to dynamically adjust their transmission directions and sub-band allocations, enabling flexible adaptation to asymmetric traffic patterns while minimizing cross-link interference through coordinated dynamic control.
2Loss of time
If full duplexing is implemented to eliminate buffering delays, then latency is reduced, but cross-link interference management complexity increases
Solution Approach 1:
By segmenting the bandwidth into full-duplex sub-bands, the system enables simultaneous uplink and downlink transmissions without requiring complex interference cancellation algorithms. The segmentation approach simplifies interference management by spatially separating conflicting transmissions, thus reducing both buffering delay and management complexity.
Solution Approach 2:
The system incorporates feedback mechanisms where neighboring nodes exchange information about their intended transmissions and received signal strengths. This feedback enables nodes to adjust their full-duplex configurations dynamically, managing cross-link interference through coordinated adaptation rather than complex processing, thereby maintaining low latency while controlling complexity.
3Strength
If downlink transmission power is increased to improve signal strength, then downlink coverage is enhanced, but cross-link interference to neighboring uplink transmissions increases
Solution Approach 1:
The frequency spectrum is segmented into full-duplex sub-bands that are allocated to different transmission directions for neighboring nodes. This segmentation allows downlink transmissions to operate at high power without causing cross-link interference to neighboring uplink transmissions, as the interference is prevented by directional allocation rather than power reduction.
Solution Approach 2:
The system applies different transmission characteristics to different spatial regions and directions. Neighboring nodes are configured with opposite transmission directions in adjacent full-duplex sub-bands, creating local quality differentiation that enables high downlink power without proportional increase in harmful interference to neighboring uplink transmissions.
Data Source
AI summary
A set of full duplex sub-band patterns, which each define downlink or uplink full duplex frequency sub-band resources during a TDD radio timing unit, are configured to RANs that are neighbors to one another. A RAN determines a traffic load, selects a full duplex sub-band pattern to accommodate the traffic load, and transmits an index associated with the selected pattern to neighboring RANs over a backhaul link. Selecting the pattern may be based on potential CLI. A neighboring RAN may adopt the selected pattern for downlink transmission. A RAN may select a compression subspace plan from among configured subspace plans and transmit, via a backhaul link, an index associated with the compression plan to neighboring RANs for use thereby in performing downlink transmission to minimize CLI. A RAN may transmit, via a backhaul link, an index associated with configured aggressor RAN action based on an uplink traffic or channel type.