TDM Subframe Segmentation for Interference Mitigation in Heterogeneous Networks
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Solution Overview
Problem
Wireless communication networks face performance degradation due to dominant interference between base stations of different types and power levels, which existing technologies struggle to effectively mitigate, especially in heterogeneous networks where interference affects both downlink and uplink communications.
Innovation Solution
The proposed solution involves reserving subframes for weaker base stations experiencing high interference from stronger ones, mitigating interference by canceling or avoiding collisions between reference signals, and optimizing relay station operations in multicast/broadcast single frequency network mode to reduce interference and improve signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base stations of different power levels operate simultaneously in the same frequency resources, then network coverage and capacity are improved, but dominant interference from strong base stations degrades communication performance of weak base stations
Solution Approach 1:
The patent segments the time domain into different subframe types (MBSFN subframes and non-MBSFN subframes) to separate transmissions from base stations of different power levels. Weak base stations transmit reference signals and control information in MBSFN subframes where strong base stations remain silent, while strong base stations use non-MBSFN subframes, thereby eliminating dominant interference and enabling reliable communication for both types of base stations simultaneously
Solution Approach 2:
The patent implements periodic transmission patterns where weak base stations alternately transmit in MBSFN subframes (with periodic silence from strong base stations) and non-MBSFN subframes (with periodic transmission from strong base stations). This periodic structure ensures that reference signals from weak base stations are transmitted during interference-free intervals, improving reception reliability while maintaining network capacity
2Productivity
If reference signals from base stations of different power levels are transmitted simultaneously on the same resources, then resource utilization is improved, but reference signal collision and interference increase
Solution Approach 1:
The patent segments reference signal transmissions by assigning weak base stations to transmit reference signals exclusively in MBSFN subframes, while strong base stations transmit reference signals in non-MBSFN subframes. This temporal segmentation eliminates reference signal collisions and interference, ensuring that reference signals from different power levels do not overlap in time-frequency resources
Solution Approach 2:
The patent introduces MBSFN subframes as an intermediary time resource where weak base stations can transmit reference signals without interference from strong base stations. The MBSFN subframe structure acts as a mediator that separates the reference signal transmissions of different base station types, allowing both to coexist without harmful interference
3Ease of operation
If TDM control symbols are transmitted by base stations in the presence of dominant interferers, then control information delivery is maintained, but reception quality degrades due to interference
Solution Approach 1:
The patent segments control information transmissions by having weak base stations transmit TDM control symbols in MBSFN subframes where strong base stations are silent, while strong base stations transmit control information in non-MBSFN subframes. This segmentation ensures that TDM control symbols from weak base stations are transmitted during interference-free intervals, improving reception quality while maintaining control information delivery
Data Source
AI summary
Techniques for supporting communication in a heterogeneous network are described. In an aspect, communication in a dominant interference scenario may be supported by reserving subframes for a weaker base station observing high interference from a strong interfering base station. In another aspect, interference due to a first reference signal from a first station (e.g., a base station) may be mitigated by canceling the interference at a second station (e.g., a UE) or by selecting different resources for sending a second reference signal by the second station (e.g., another base station) to avoid collision with the first reference signal. In yet another aspect, a relay may transmit in an MBSFN mode in subframes that it listens to a macro base station and in a regular mode in subframes that it transmits to UEs. In yet another aspect, a station may transmit more TDM control symbols than a dominant interferer.