NB-IoT TDD Search Space Configuration for Control Channel Monitoring
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently transmitting and receiving physical downlink control channels in time division duplex (TDD) mode, particularly in narrowband Internet-of-Things (NB-IoT) systems, due to resource limitations and inefficiencies in special subframes.
Innovation Solution
A method and apparatus for configuring a search space for the physical downlink control channel, excluding aggregation level 1 in TDD special subframes, which includes a downlink period, guard period, and uplink period, to optimize channel monitoring and transmission in NB-IoT systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If search space is configured with aggregation level 1 in TDD special subframe, then channel monitoring coverage is maximized, but receiver complexity and decoding difficulty increase
Solution Approach 1:
The patent extracts aggregation level 1 from the search space configuration in TDD special subframes, excluding it from valid aggregation levels. This removes the most complex decoding case (aggregation level 1) while maintaining support for aggregation levels 2, 4, and 8, thereby reducing receiver complexity without completely sacrificing monitoring coverage.
Solution Approach 2:
The patent changes the parameter of valid aggregation levels from the standard set {1, 2, 4, 8} to a modified set {2, 4, 8} for TDD special subframes. This parameter modification optimizes the balance between coverage and complexity by eliminating the lowest aggregation level that causes excessive receiver burden.
2Reliability
If search space is configured with multiple aggregation levels in TDD special subframe, then channel monitoring robustness is improved, but processing time and complexity increase
Solution Approach 1:
The patent removes aggregation level 1 from the set of valid aggregation levels in TDD special subframes. This extraction eliminates the most time-consuming and complex decoding operation while retaining multiple other aggregation levels (2, 4, 8) that provide robustness through diversity, thus reducing processing time while maintaining monitoring robustness.
3Adaptability or versatility
If search space configuration includes all standard aggregation levels, then decoding flexibility is maximized, but resource overhead and complexity increase
Solution Approach 1:
The patent modifies the search space configuration parameters by restricting valid aggregation levels to {2, 4, 8} for TDD special subframes, excluding aggregation level 1. This parameter change maintains decoding flexibility through multiple aggregation level options while reducing configuration complexity and resource overhead by eliminating one aggregation level variant.
Data Source
AI summary
The present invention relates to a method for receiving a signal in a wireless communication system supporting narrowband Internet of things (NB-IoT) operated in time division duplex (TDD) and a device therefor, the method comprising the steps of: configuring a search space for a physical downlink control channel; and monitoring the physical downlink control channel on the basis of the configured search space, wherein the search space is configured by a TDD special subframe from which aggregation level 1 has been excluded, and the TDD special subframe indicates a subframe including a downlink period, a guard period, and an uplink period.