PBCH Subband Allocation for CIoT Coverage Classes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems for cellular Internet-of-Things (CIoT) face challenges in efficiently transmitting system information while reducing costs and battery consumption, particularly for low-complexity user equipment (UEs) that require low data rate and long battery life, and need to operate in challenging coverage conditions.
Innovation Solution
The method involves configuring a physical broadcast channel (PBCH) in a subband of consecutive subcarriers in the frequency domain and allocating different subcarriers for each coverage class to transmit system information efficiently, using techniques such as frequency hopping and resource block allocation to optimize power consumption and network capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If system information is transmitted using conventional methods in LTE, then network coverage is maintained, but power consumption increases and indoor coverage performance deteriorates
Solution Approach 1:
The system divides CIoT devices into different coverage classes based on their reception capability. Coverage Class 1 devices use conventional PBCH transmission, while Coverage Class 2 devices use enhanced repetition-based transmission. This segmentation allows each device type to use the most efficient transmission method, reducing overall power consumption while maintaining reliability for challenging environments.
Solution Approach 2:
The patent changes the transmission parameter of PBCH by introducing repetition transmissions for Coverage Class 2 devices. The base station transmits PBCH multiple times (e.g., 4 repetitions) for devices in coverage-enhanced mode, improving reception reliability in indoor scenarios without forcing all devices to use this power-intensive method.
2Device complexity
If bandwidth is reduced for low-complexity UEs, then cost and battery consumption decrease, but system information transmission efficiency deteriorates
Solution Approach 1:
The patent applies different transmission qualities to different device groups. Coverage Class 1 devices (with better coverage) receive standard PBCH transmission, while Coverage Class 2 devices (in challenging coverage) receive enhanced repetition transmissions. This local differentiation ensures that devices with narrow bandwidth capabilities can still acquire system information efficiently without forcing all devices to use high-complexity wideband methods.
3Reliability
If PBCH is transmitted repeatedly for coverage enhancement, then indoor coverage improves, but network capacity and spectral efficiency deteriorate
Solution Approach 1:
The system segments devices into Coverage Class 1 and Coverage Class 2 based on their coverage requirements. Only Coverage Class 2 devices receive repeated PBCH transmissions, while Coverage Class 1 devices use standard single-transmission PBCH. This segmentation ensures that repetition-based coverage enhancement is applied only where necessary, preserving network capacity for devices that don't require it.
4Reliability
If separate PDCCH resources are allocated for each coverage class, then transmission reliability improves, but device complexity and resource management increase
Solution Approach 1:
The patent implements a self-service mechanism where CIoT devices autonomously determine their coverage class based on downlink coverage measurements. Devices compare measured reference signal received power (RSRP) against thresholds to self-identify as Coverage Class 1 or Coverage Class 2. This eliminates the need for complex network-side device classification while ensuring reliable transmission resource allocation.
Data Source
AI summary
A method and apparatus for transmitting system information in a wireless communication system is provided. A base station (BS) configures a physical broadcast channel (PBCH) in a subband including a set of consecutive subcarriers in a frequency domain, and transmits master information via the PBCH.