Base Station Search Space Distribution for Carrier Aggregation
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Solution Overview
Problem
In LTE-Advanced communication systems, the existing methods for configuring search spaces in a wide band with aggregated component carriers face challenges in preventing overlapping of search spaces between different component carriers and user terminals, leading to inefficiencies in downlink control channel transmission.
Innovation Solution
A base station apparatus is configured with a control information generation section, a determining section, and a transmission section that use fundamental frequency block-specific and user terminal-specific offset values to arrange and distribute search spaces, preventing overlap by calculating offset values using equations that account for component carrier-specific and user terminal-specific indices, thereby ensuring separate search spaces between fundamental frequency blocks and user terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If search spaces are configured in a wide band with aggregated component carriers, then the communication system can support carrier aggregation and widen the bandwidth, but search spaces may overlap between different component carriers and user terminals
Solution Approach 1:
The patent applies local quality by making search space configurations specific to each component carrier and user terminal. By introducing component carrier-specific indices and user terminal-specific indices into the search space determination equations, each user terminal receives downlink control information in uniquely identified search spaces on each component carrier, preventing overlap while maintaining carrier aggregation capability
Solution Approach 2:
The patent changes parameters by introducing offset values derived from component carrier-specific and user terminal-specific indices into the search space determination process. These offset values modify the starting positions and sizes of search spaces, ensuring that search spaces for different component carriers and user terminals do not overlap, thus resolving the contradiction between carrier aggregation and search space separation
2Reliability
If blind decoding is performed over the whole range of PDCCH, then all downlink control information can be detected, but the mobile station load increases significantly
Solution Approach 1:
The patent applies segmentation by dividing the PDCCH range into specific search spaces for each user terminal on each component carrier. Instead of performing blind decoding over the entire PDCCH range, user terminals only perform blind decoding within their assigned search spaces, which are determined using component carrier-specific and user terminal-specific indices. This segmentation significantly reduces the mobile station processing load while ensuring reliable detection of downlink control information
Data Source
AI summary
A base station apparatus having a control information generation section that generates, per fundamental frequency block, a downlink control information piece for demodulating a data channel that is transmitted for each of a plurality of fundamental frequency blocks assigned to a user terminal, a determining section that determines, per fundamental frequency block, a search space which is a candidate area where the downlink control information piece is arranged, and a transmission section that transmits a downlink control channel in which the search space containing the downlink control information piece is arranged is disclosed. The control information generation section arranges respective downlink control information pieces corresponding to the fundamental frequency blocks in a downlink control channel of a specific fundamental frequency block among the fundamental frequency blocks, and the determining section distributes positions of search spaces such that the search spaces are separate between fundamental frequency blocks and between user terminals.