TDD Node Frequency Partitioning for Crosslink Interference
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Solution Overview
Problem
In cellular Time Division Duplex (TDD) networks, adjacent cells with different TDD patterns experience unwanted crosslink interference due to dynamic reconfiguration of time slots, which affects uplink and downlink traffic requirements.
Innovation Solution
Implementing a system where nodes in adjacent cells use different parts of the frequency range for time slots with differing communication modes, creating a fractional frequency reuse within the TDD pattern, and synchronizing patterns to minimize overlapping time slots with differing modes, thereby reducing crosslink interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different TDD patterns are used in adjacent cells to adapt to different uplink/downlink traffic requirements, then adaptability is improved, but crosslink interference increases
Solution Approach 1:
The patent applies local quality by differentiating frequency resource allocation between cells based on their specific TDD patterns. Each cell uses different frequency parts (first part vs second part) in time slots where their communication modes differ, creating localized frequency separation exactly where needed at cell boundaries with different TDD patterns, while allowing full frequency usage in non-overlapping or same-mode slots.
Solution Approach 2:
The patent changes the frequency parameter dynamically based on time slot and cell location. Nodes adjust which frequency part to use depending on the communication mode (uplink/downlink) of their current time slot and their position relative to adjacent cells, creating a dynamic frequency allocation scheme that adapts to TDD pattern variations while suppressing crosslink interference.
2Object-affected harmful factors
If frequency resources are restricted to reduce crosslink interference, then harmful factors are reduced, but traffic capacity decreases
Solution Approach 1:
The patent implements dynamic frequency resource allocation where nodes can use different frequency parts depending on the communication mode of the current time slot. This dynamic approach allows the system to suppress crosslink interference only when necessary (in time slots with different communication modes between adjacent cells) while maintaining full frequency usage in other slots, thus preserving overall traffic capacity.
Solution Approach 2:
The patent segments the frequency range into different parts (first part and second part) that can be allocated differently to adjacent cells based on their TDD patterns. This segmentation allows selective frequency restriction only in specific time slots where crosslink interference occurs, rather than permanently restricting the entire frequency range, thereby maintaining higher overall traffic capacity.
Data Source
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AI summary
In a system (1) of a first and a second node (2i, 2i+1) for a cellular network operating in Time Division Duplex, TDD, mode the first node (2i) is configured to wirelessly communicate (8, 9) with user equipments (3k) according to a first pattern (Pi) of time slots (ST) each having a communication mode of either uplink (U) or downlink (D) or mixed (S), and the second node (2i+1) is configured to wirelessly communicate (8, 9) with user equipments (3k+1) according to a second pattern (Pi+1) of time slots (ST) each having a communication mode of either uplink (U) or downlink (D) or mixed (S), wherein the first node (2i) is configured to use, in a time slot (ST) of the first pattern (Pi) whose communication mode (U, D, S) differs from the communication mode (U, D, S) of an overlapping time slot (ST) of the second pattern (Pi+1), only a first part (A) of the frequency range (BW) of the cellular network, and the second node (2i+1) is configured to use in said overlapping time slot (ST) only a second part (B) of the frequency range (BW).