Control Channel Placement for Wireless Decoding Latency
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Solution Overview
Problem
The existing LTE and LTE-A wireless communication systems face challenges in blind decoding of control channels, leading to decoding latency and reduced system performance due to limited contiguous search spaces and poor channel gain, especially with the introduction of new features like carrier aggregation and MIMO beamforming.
Innovation Solution
A method where the network uniformly distributes control channels across logical domains, allowing mobile devices to monitor and decode control information from multiple candidates with better frequency scheduling gain, optimizing the placement of control channel candidates to improve channel gain and reduce decoding latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control channels are placed in contiguous search space for simplicity, then device complexity is reduced, but channel gain deteriorates
Solution Approach 1:
The search space is divided into multiple segments corresponding to different aggregation levels (L=1, 2, 4, 8), with each segment containing control channel candidates at its respective aggregation level. This segmentation allows the system to distribute control channels across different regions of the search space, improving channel gain while maintaining manageable device complexity through structured organization.
Solution Approach 2:
Different regions of the search space are assigned different properties based on aggregation level. Lower aggregation levels (L=1, 2) are placed in regions with better channel conditions, while higher aggregation levels (L=4, 8) are placed in other regions. This local quality differentiation optimizes channel gain for each aggregation level while maintaining overall system simplicity.
2Device complexity
If the number of PDCCH candidates is limited to reduce UE complexity, then device complexity is reduced, but decoding latency increases
Solution Approach 1:
The network pre-configures the UE with the complete set of PDCCH candidates across all aggregation levels and their positions in the search space before actual control channel transmission. This preliminary configuration allows the UE to have all decoding candidates ready in advance, reducing decoding latency when actual control information needs to be received, while maintaining manageable complexity through the pre-established structure.
3Device complexity
If all PDCCH candidates are contiguous in CCE domain for simplicity, then device complexity is reduced, but system performance deteriorates
Solution Approach 1:
The contiguous CCE domain is segmented into multiple regions, each dedicated to specific aggregation levels. This segmentation allows control channels to be distributed across different CCE regions according to their aggregation level requirements, improving system performance through better resource utilization while maintaining the simplicity of contiguous structure within each segment.
Solution Approach 2:
The system changes the parameter of search space distribution from completely contiguous to segmented-contiguous, where each aggregation level has its own contiguous region. This parameter change enables better frequency scheduling gain and channel gain while preserving the simplicity of contiguous allocation within each aggregation level's region.
Data Source
AI summary
A method of blind decoding of a control channel for a wireless communication system comprising a network and a mobile device is disclosed. The network selects at least one of a plurality of control channels of at least one logical domain of control channel element, for transmitting control information to the mobile device, wherein the plurality of control channels of each logical domain are uniformly distributed over the logical domain. On the other side, the mobile device monitors all of the control channel candidates of each of the at least one logical domain of control channel element, for obtaining the control information which is transmitted from the network and configured to the mobile device, wherein all of the control channel candidates of each logical domain are uniformly distributed over the logical domain.