CoMP Response Signal Orthogonality via Common Hopping Pattern
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Solution Overview
Problem
In CoMP communication, response signals from different terminals interfere with each other due to non-orthogonal ZAC sequences and hopping patterns, leading to degraded CoMP quality, and existing solutions increase uplink control channel overhead when trying to separate time and frequency resources.
Innovation Solution
A terminal and base station configuration that uses a common hopping pattern for multiple channels, allowing first spreading with separable sequences and controlling the sequence usage based on a common hopping pattern among coordinated multipoint reception base stations, and a correlation processing section to combine correlation values from multiple base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If different terminals use different ZAC sequences with different cyclic shift amounts for code-multiplexing response signals, then the number of multiplexed terminals increases, but response signals from different terminals interfere with each other in CoMP reception
Solution Approach 1:
The patent applies local quality by assigning different cyclic shift amounts to different terminals based on their specific reception characteristics. Each terminal's response signal is spread with a ZAC sequence having a cyclic shift amount specifically suited to that terminal's channel conditions, allowing optimal local performance while maintaining overall system capacity.
Solution Approach 2:
The patent changes the cyclic shift amount parameter of ZAC sequences to resolve interference in CoMP reception. By adjusting this parameter based on reception quality metrics, the system maintains orthogonality between response signals from different terminals while preserving the ability to multiplex multiple terminals.
2Object-affected harmful factors
If time and frequency resources are separated to avoid interference in CoMP communication, then response signal quality improves, but uplink control channel overhead increases
Solution Approach 1:
Instead of separating time and frequency resources, the patent changes the cyclic shift parameter of ZAC sequences to achieve orthogonality. This parameter-based solution eliminates interference while maintaining resource efficiency and avoiding the overhead associated with resource separation.
Solution Approach 2:
The patent transitions from resolving interference in the time-frequency domain (through resource separation) to resolving it in the cyclic shift domain. By exploiting the additional dimension of cyclic shift amounts, the system achieves orthogonality without sacrificing time or frequency resources.
3Object-affected harmful factors
If a common hopping pattern is used for multiple channels in CoMP reception, then response signals become orthogonal and interference-free, but sequence allocation complexity increases
Solution Approach 1:
The patent applies universality by using a common hopping pattern for multiple channels (PUCCH and PUSCH). This single hopping pattern serves multiple functions: it provides orthogonality between response signals, maintains consistency across different channel types, and simplifies overall sequence allocation while preventing interference.
Solution Approach 2:
The patent promotes homogeneity by applying the same hopping pattern across different channels and terminal types. This uniform approach ensures consistent orthogonal behavior throughout the system, making sequence allocation more manageable while effectively preventing interference between response signals.
Data Source
AI summary
A wireless communication terminal apparatus wherein CoMP communication can normally be performed without increasing the overhead of an upstream line control channel. In this apparatus, a spreading unit (214) primarily spreads a response signal by use of a ZAC sequence established by a control unit (209). A spreading unit (217) secondarily spreads the response signal, to which CP has been added, by use of a block-wise spread code sequence established by the control unit (209). The control unit (209) controls, in accordance with sequence numbers and a hopping pattern established therein, the circular shift amount of the ZAC sequence to be used for the primary spread in the spreading unit (214) and the block-wise spread code sequence to be used for the secondary spread in the spreading unit (217). The hopping pattern established in the control unit (209) is a hopping pattern common to a plurality of base stations that CoMP-receive the response signal.