NB-PDCCH Narrowband Resource Mapping for LTE
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Solution Overview
Problem
The existing LTE system cannot transmit PDCCH within the narrow bandwidth required by NBIOT systems, which necessitates a new physical downlink channel resource mapping method.
Innovation Solution
A method for transmitting a narrowband physical downlink control channel (NB-PDCCH) in an NBIOT system by mapping it to a basic element with a frequency resource bandwidth of less than or equal to 180 kHz, allowing PDCCH transmission in the NBIOT system, and utilizing NB-CCEs for resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PDCCH is transmitted using LTE system bandwidth standards, then the control channel can be transmitted with standard resource allocation, but it cannot be transmitted within the narrow bandwidth required by NBIOT systems
Solution Approach 1:
The patent segments the narrowband control channel resources by dividing the 180 kHz NBIOT bandwidth into smaller resource blocks (RBs) of 12 subcarriers each. This segmentation allows the PDCCH to be mapped to specific RB pairs within the narrow bandwidth, making it adaptable to NBIOT terminal capabilities while maintaining structured resource allocation similar to LTE standards.
Solution Approach 2:
The patent changes the bandwidth parameter from standard LTE bandwidths (1.4 MHz minimum) to narrowband 180 kHz bandwidth specifically for NBIOT PDCCH transmission. This parameter change enables the control channel to operate within the limited bandwidth of NBIOT terminals while preserving the fundamental LTE PDCCH functionality and resource mapping structure.
2Adaptability or versatility
If the PDCCH bandwidth is reduced to match NBIOT terminal capabilities, then narrowband communication is enabled, but the minimum system standard bandwidth requirement of 1.4 MHz cannot be met
Solution Approach 1:
The patent implements dynamic bandwidth adaptation by allowing the PDCCH to be transmitted flexibly within the narrow 180 kHz bandwidth when NBIOT terminals are detected, while maintaining the capability to switch to standard LTE bandwidth modes when regular LTE terminals are present. This dynamic approach enables the system to comply with both narrowband requirements and standard LTE specifications depending on the active terminal type.
Solution Approach 2:
The patent applies local quality by creating a specialized narrowband resource allocation structure specifically for NBIOT terminals within the broader LTE framework. The resource mapping is optimized locally for 180 kHz bandwidth with RB pairs configured specifically for narrowband operation, while the overall system maintains standard LTE compliance for other terminals through coexistence mechanisms.
Data Source
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AI summary
Embodiments of the present invention relate to the communications field, and provide a physical downlink channel transmission method, an apparatus, and a system to resolve a problem that a PDCCH in an LTE system cannot be transmitted within a narrow bandwidth. The transmission method includes: transmitting, by a base station, a narrowband physical downlink control channel NB-PDCCH in an nth downlink subframe or a downlink pilot timeslot DwPTS in an nth subframe to a user terminal, where the NB-PDCCH is mapped to an NB-PDCCH mapped basic element, the NB-PDCCH mapped basic element includes a first frequency resource or a second frequency resource in a frequency domain and includes at least one orthogonal frequency division multiplexing OFDM symbol included in the nth downlink subframe or the downlink pilot timeslot DwPTS in the nth subframe in a time domain, a bandwidth of the first frequency resource is less than or equal to 180 kHz, the second frequency resource is a frequency resource included in a resource block RB, and n≥1.