LTE Control Channel Search Space Segmentation for Power Reduction
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Solution Overview
Problem
Conventional LTE communications devices, particularly reduced capability or MTC type devices, face challenges in power consumption and complexity due to the need to search through all possible combinations of control channel elements (CCEs) for downlink control information, which increases power usage and reduces battery life.
Innovation Solution
The solution involves configuring communications devices to search only a predetermined subset of possible CCEs for downlink control information, reducing the search space and thus the power consumption, by selecting a fixed or configurable aggregation level for the downlink control channel elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device searches through all possible combinations of control channel elements (CCEs) for downlink control information, then the reliability of receiving control information is improved, but the power consumption increases and battery life decreases
Solution Approach 1:
The patent segments the search space by dividing CCEs into first search spaces (common search spaces) and second search spaces (UE-specific search spaces). The device is configured to search only the first search spaces for control information, eliminating the need to search all possible CCE combinations. This segmentation reduces the search space while maintaining reliable reception of control information intended for the device.
Solution Approach 2:
The patent applies local quality by differentiating between common search spaces that all UEs monitor and UE-specific search spaces that only specific UEs monitor. The device is configured with specific search space characteristics, allowing it to optimize its search behavior based on local requirements rather than searching the entire control region uniformly.
2Reliability
If the device searches through all possible combinations of control channel elements (CCEs), then the completeness of control information reception is improved, but the device complexity increases
Solution Approach 1:
The patent segments the control region into distinct search spaces with different search characteristics. By configuring the device to search only the first search spaces (common search spaces) rather than all possible CCE combinations, the device complexity is reduced while maintaining complete reception of relevant control information.
Solution Approach 2:
The patent introduces dynamic search space configuration where the device can be configured with different search space parameters including aggregation levels and search space indices. This dynamic configuration allows the device to adapt its search behavior based on current conditions without implementing a fixed complex search algorithm.
3Device complexity
If the device uses a simple receiver unit with limited capabilities, then the device cost and complexity are reduced, but the ability to receive comprehensive control information is worsened
Solution Approach 1:
The patent segments the control information reception task by identifying that certain control information (first search spaces) can be received using simple receiver capabilities. The device is configured to search only these first search spaces, which can be decoded with limited complexity, rather than requiring comprehensive capabilities to search all CCEs.
Solution Approach 2:
The patent extracts the essential control information that can be received with limited device capabilities from the full set of possible control information. By focusing search efforts on first search spaces that contain information relevant to all UEs and can be decoded with simple receivers, the patent enables low-complexity devices to receive necessary control information without requiring comprehensive receiver capabilities.
Data Source
AI summary
A communications device transmitting/receiving data to/from a mobile communications network includes a transmitter to transmit data to the mobile communications network via a wireless access interface, a receiver to receive data from the mobile communications network via the wireless access interface, and a controller. The wireless access interface includes plural time divided temporal units and in each temporal unit a down-link control channel and a downlink shared channel. The temporal units may be sub-frames of an LTE carrier. The controller can control the receiver to receive downlink control channel information transmitted by the mobile communications network in one or more control channel elements of the downlink control channel, and to receive the downlink control channel information by searching the downlink control channel in a predetermined sub-set of plural possible sets of control channel elements in one or more of the temporal units according to a fixed aggregation level.