CoMP Reference Signal Reception With Adaptive ZC Hopping
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Solution Overview
Problem
Existing methods for channel quality estimation in Coordinated Multiple Point (CoMP) transmission and reception in LTE-Advanced systems face issues of inter-cell interference due to non-orthogonal ZC sequence usage, leading to inaccurate CQI estimation and deteriorated system throughput.
Innovation Solution
A radio communication apparatus and method that employs a hopping pattern calculation section to dynamically switch ZC sequence numbers for CoMP and Non-CoMP terminals, generating orthogonal ZC sequences to reduce interference within and outside CoMP sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ZC sequences with different ZC sequence numbers are used for SRS transmission in CoMP terminals, then inter-cell interference is reduced, but cross-correlation occurs at certain levels leading to inaccurate CQI estimation
Solution Approach 1:
The patent applies dynamics by making the ZC sequence number selection adaptive rather than static. The terminal dynamically selects ZC sequence numbers based on reception timing differences detected between serving cell and non-serving cell reference signals. This dynamic adaptation allows the system to maintain orthogonality under varying propagation conditions while minimizing inter-cell interference and cross-correlation effects.
Solution Approach 2:
The patent changes the parameter of ZC sequence number selection based on propagation conditions. By adjusting which ZC sequence numbers are used according to the detected timing differences and channel conditions, the system optimizes the balance between reducing inter-cell interference and maintaining accurate CQI estimation, resolving the contradiction between these two objectives.
2Reliability
If CoMP transmission and reception is implemented across multiple cells, then reception quality is improved, but terminal scheduling complexity increases due to coordinated scheduling among multiple cells
Solution Approach 1:
The patent segments the scheduling complexity by separating the functions of different cells. The serving cell handles primary scheduling and control, while non-serving cells provide reference signals for timing detection and coordinated reception. This segmentation allows multiple cells to participate in CoMP without requiring all cells to perform full scheduling functions, thereby reducing overall system complexity while maintaining reception quality improvements.
3Object-affected harmful factors
If ZC sequence groups are assigned to reduce inter-cell interference, then orthogonal ZC sequences are achieved, but the number of available ZC sequence groups is limited to 30
Solution Approach 1:
The patent makes ZC sequence number selection dynamic rather than relying solely on static assignment from a limited set of 30 sequence groups. By dynamically selecting appropriate ZC sequence numbers based on detected timing differences and propagation conditions, the system effectively expands the available sequence options beyond the fixed 30 groups, improving adaptability while maintaining orthogonality and interference reduction benefits.
Solution Approach 2:
The patent changes the approach from fixed ZC sequence group assignment to flexible ZC sequence number selection based on channel conditions. This parameter change allows the system to adaptively choose from available sequences according to actual propagation characteristics, effectively increasing versatility without requiring more than 30 sequence groups while still achieving inter-cell interference reduction.
Data Source
AI summary
Provided are a wireless communication apparatus and a reference signal generating method, wherein inter-cell interference is reduced inside and outside a CoMP set. A CoMP mode setting unit (101) sets whether the terminal (100) thereof is a CoMP terminal or a Non-CoMP terminal. When the terminal (100) is set as a Non-CoMP terminal, the hopping pattern calculating unit (104) calculates a ZC sequence number to be used as the transmission timing, from among all the ZC sequence numbers that can be used within the system. When the terminal (100) is set as a CoMP terminal, the hopping pattern calculating unit (104) calculates a ZC sequence number to be used as the transmission timing, by hopping the ZC sequence numbers to be used within the CoMP set. A ZC sequence generating unit (105) generates a ZC sequence to be used as an SRS, using the calculated ZC sequence number.