Sub-Carrier Selective Cyclic Delay Diversity for Wireless Throughput
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Solution Overview
Problem
In multiple-antenna wireless communication systems, existing cyclic delay diversity techniques often result in throughput deterioration when applied to receiving ends that do not require cyclic delay diversity, especially in multiple access systems like OFDMA, due to phase shifts affecting all sub-carriers.
Innovation Solution
A sub-carrier selective approach is implemented, where a cyclic delay diversity controller selects specific sub-carriers for phase shifting, using phase shifters to compensate for relative phase variations in shadow zones, thereby preventing throughput deterioration in receiving ends that do not require cyclic delay diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic delay diversity is applied to all sub-carriers in multiple-antenna systems, then shadow zones are compensated and signal reception is improved, but throughput deteriorates in receiving ends that do not require cyclic delay diversity
Solution Approach 1:
The patent applies cyclic delay diversity selectively to specific sub-carriers rather than uniformly to all sub-carriers. The controller identifies which sub-carriers require CDD based on channel conditions and applies phase shifting only to those specific sub-carriers, leaving other sub-carriers unchanged. This localised application resolves the contradiction by providing shadow zone compensation only where needed while maintaining normal throughput performance in receiving ends that do not require CDD.
2Reliability
If phase shifting is applied to all sub-carriers, then relative phase variations are compensated, but system complexity increases and unnecessary processing is performed
Solution Approach 1:
The patent extracts and isolates only the sub-carriers that require phase shifting for shadow zone compensation. The controller identifies specific sub-carriers needing CDD and applies phase shifting exclusively to those, rather than processing all sub-carriers uniformly. This extraction approach reduces system complexity by eliminating unnecessary processing operations while maintaining effective phase variation compensation for the required sub-carriers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for simultaneous communication in multiple-antenna systems by applying cyclic delay diversity only to necessary sub-carriers, enhancing system performance and preventing throughput loss in receiving ends that do not require it.
Implementation Method 1
at least one shifter for shifting a phase of a signal mapped to the at least one selected sub-carrier
Data Source
AI summary
A cyclic delay diversity (CDD) technique in a multiple-antenna broadband wireless communication system is provided. An apparatus in the multiple-antenna broadband wireless communication system includes: a controller for selecting at least one sub-carrier to which CDD is applied; at least one shifter for shifting a phase of a signal mapped to the at least one selected sub-carrier; and an operator for converting the signal, which is mapped to the at least one selected sub-carrier and whose phase is shifted, and other signals mapped to the remaining sub-carriers into time-domain signals.