LTE Control Channel Interleaving for Interference Randomization
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Solution Overview
Problem
Existing symbol group interleaving methods in LTE systems are inflexible and fail to effectively randomize interference across varying frequency bandwidths, OFDM symbol allocations, and changing CCE or CCE group sizes, leading to suboptimal interference randomization and frequency diversity.
Innovation Solution
A flexible symbol group interleave approach that allows for different interleaving patterns across cells, incorporating cell-specific cyclic shifts and the use of Quadratic Permutation Polynomials or prime number interleaves to handle varying control channel parameters, ensuring interference randomization and frequency diversity by renumbering and strategically placing symbol groups within available resource blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common interleaving scheme for CCE groups is used across different cells, then the complexity of interference coordination is reduced, but interference randomization between control channels from different cells is insufficient
Solution Approach 1:
The patent applies local quality by introducing cell-specific cyclic shifts to the common interleaving scheme. Each cell applies a unique cyclic shift value to its CCE group, creating locally differentiated interference patterns while maintaining the global common interleaving structure. This resolves the contradiction by keeping the overall system simple while adding localized variation to randomize interference.
Solution Approach 2:
The patent changes the parameter of cyclic shift values applied to CCE groups in different cells. By varying this parameter across cells, the patent achieves interference randomization without fundamentally changing the interleaving scheme structure, thus maintaining low complexity while improving interference randomization.
2Object-affected harmful factors
If interference avoidance techniques are used to coordinate transmissions between base stations, then interference at mobiles is reduced, but the system complexity and coordination overhead increase
Solution Approach 1:
The patent enables base stations to self-randomize their interference patterns through cell-specific cyclic shifts applied to CCE groups. Each base station independently applies its own cyclic shift based on cell identity, eliminating the need for complex inter-base station coordination while still achieving interference randomization and reduction.
3Adaptability or versatility
If the number of control channel elements or CCE group sizes are changed to adapt to varying traffic conditions, then system flexibility is improved, but the interleaving scheme becomes less predictable and harder to manage
Solution Approach 1:
The patent creates a universal interleaving framework that works with varying CCE group sizes and configurations. The common interleaving scheme combined with cell-specific cyclic shifts provides a multi-functional solution that adapts to different traffic conditions and CCE configurations without requiring separate management procedures, thus maintaining simplicity while improving flexibility.
Data Source
AI summary
A method and a radio base station for interleaving control channel data to be transmitted in a telecommunications system are described. The method comprises grouping the control channel elements CCE1-CCEn into a first order of control channel symbol groups, adding symbol groups comprising dummy values or zeros to the first order of control channel symbol groups based on a number of available symbol group positions for the shared control channel, interleaving the first order of the control channel symbol groups resulting in an a second order, and mapping the second order of control channel symbol groups to the available control channel transmission resources.