Intra-eNB DL CoMP Interference Cancellation
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Solution Overview
Problem
Conventional methods for mitigating inter-cell interference (ICI) in LTE cellular networks, such as averaging, ICI cancellation, and static fractional frequency reuse, are ineffective in improving downlink performance, especially at cell edges due to high implementation complexity and resource constraints.
Innovation Solution
A system and method for cancelling ICI between UEs in adjacent sectors by forming a downlink CoMP operational set, estimating channel matrix blocks, calculating inverse channel block matrices, and performing pre-coding to generate output signals that enable interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ICI mitigation methods (averaging, ICI cancellation, static fractional frequency reuse) are used, then implementation complexity and resource consumption increase, but downlink performance improvement is limited
Solution Approach 1:
The patent transitions from static fractional frequency reuse to dynamic coordinated multipoint transmission. The system dynamically forms downlink CoMP operational sets based on real-time channel conditions and UE locations, allowing flexible adaptation to changing network states. This dynamic approach enables continuous optimization of resource allocation and interference coordination without requiring complex receiver-side processing.
Solution Approach 2:
The patent introduces a coordinated multipoint operational set as an intermediary structure that manages interference between adjacent sectors. By forming groups of UEs from different sectors that experience mutual interference and coordinating their transmission through channel matrix block estimation and pre-coding, the system achieves interference mitigation without requiring complex receiver-side cancellation algorithms.
2Object-affected harmful factors
If static fractional frequency reuse is used to avoid resource collisions near sector borders, then resource utilization efficiency decreases, but ICI is reduced
Solution Approach 1:
The system replaces static frequency allocation with dynamic resource coordination. The downlink CoMP operational sets are formed and adjusted based on current channel conditions, UE positions, and interference patterns. This allows the system to dynamically allocate resources to UEs in adjacent sectors, maximizing resource utilization while continuously managing interference through coordinated transmission and pre-coding operations.
Solution Approach 2:
The patent changes the allocation parameters from fixed frequency chunks to dynamic operational sets. By estimating channel matrix blocks and calculating pre-coding matrices based on current system state, the system adapts resource allocation parameters in real-time. This enables full frequency reuse in practice while maintaining interference control through coordinated multipoint transmission rather than relying on static fractional reuse.
3Object-affected harmful factors
If receiver-side ICI cancellation techniques (MMSE-SIC, IRC) are used, then ICI is reduced, but receiver complexity and power consumption increase significantly
Solution Approach 1:
The patent applies preliminary interference cancellation at the transmitter side through downlink CoMP operational sets and pre-coding. By estimating channel matrix blocks and calculating sector-specific cross-sector pre-coding matrices before transmission, the system pre-eliminates interference in the transmitted signals. This approach cancels ICI before it reaches the receiver, eliminating the need for complex receiver-side cancellation algorithms and keeping UE receivers simple.
Solution Approach 2:
The system introduces transmitter-side coordination as an intermediary mechanism to prevent interference rather than requiring receiver-side cancellation. The downlink CoMP operational sets and pre-coding matrices act as intermediaries that manage interference at the source, transferring the complexity from the UE receiver to the network infrastructure where it can be handled more efficiently.
Data Source
AI summary
A system and method of cancelling downlink inter-channel interference between a first selected UE in one sector of a cell and a second selected UE in a second sector of said cell by using intra-eNB DL CoMP is described. UEs which are affected by ICI are identified in sectors which are adjacent to each other in the cell. A downlink CoMP operational set is formed for the identified UEs. Channel matrix blocks are estimated for the first and second selected UEs. The channel matrix blocks are representations of the channel characteristics between the first and second UE, in their respective sectors and the serving base station. The estimated channel matrix blocks are then loaded into a cross-sector channel block matrix. The inverse values of the channel matrix blocks are then calculated to form a sector specific cross-sector pre-coding matrix which is used to enable interference cancellation.