Narrowband Synchronization Signal Design for IoT
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Solution Overview
Problem
Current narrowband IoT (NB-IoT) technologies face challenges in efficiently transmitting and receiving synchronization signals, which are crucial for NB-IoT operation, particularly in reducing complexity and power consumption while maintaining effective cell identification and synchronization.
Innovation Solution
The method involves transmitting and receiving narrowband synchronization signals using specific sequences such as Zadoff-Chu sequences and interleaved m-sequences, with techniques like repeated transmission of PSS in multiple OFDM symbols and divisional mapping of SSS across OFDM symbols to enhance correlation properties and reduce computational load, thereby simplifying the reception process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If narrowband synchronization signals are transmitted using conventional LTE methods, then cell identification and synchronization can be achieved, but apparatus complexity and power consumption increase
Solution Approach 1:
The synchronization signal transmission is segmented into specific narrowband frequency regions (e.g., center 3 PRBs or guard band PRBs) rather than across the entire LTE bandwidth. This segmentation allows NB-IoT devices to process only the relevant narrowband portion, reducing computational complexity while maintaining synchronization functionality
Solution Approach 2:
The synchronization signal transmission extracts and isolates specific frequency resources from the LTE spectrum, dedicating particular PRBs for NB-PSS and NB-SSS transmission. This extraction enables devices to focus processing on extracted narrowband signals, reducing overall processing complexity
2Reliability
If narrowband synchronization signals are transmitted using conventional LTE methods, then cell identification and synchronization can be achieved, but power consumption increases
Solution Approach 1:
By segmenting the frequency spectrum into narrowband regions and transmitting synchronization signals only in these segmented regions, the patent enables devices to reduce their receiver bandwidth and processing load, directly reducing power consumption while maintaining synchronization reliability
Solution Approach 2:
The patent changes the frequency domain parameters by confining synchronization signal transmission to specific narrowband PRB allocations rather than full bandwidth. This parameter change enables power-efficient reception by allowing devices to process only the necessary narrowband frequency components
3Area of stationary object
If synchronization signals are transmitted across the entire LTE bandwidth, then comprehensive coverage is achieved, but NB-IoT device processing complexity increases
Solution Approach 1:
The patent segments the LTE frequency bandwidth into specific narrowband regions (1 PRB = 180 kHz) for synchronization signal transmission. This segmentation allows NB-IoT devices to process only the segmented narrowband portion rather than the entire LTE bandwidth, reducing processing complexity while maintaining coverage
4Measurement precision
If repeated transmission of PSS in multiple OFDM symbols is implemented, then correlation properties improve, but transmission time increases
Solution Approach 1:
The patent implements periodic repetition of the NB-PSS across multiple OFDM symbols within the narrowband allocation. This periodic action enhances correlation properties by providing multiple opportunities for detection, while the repetition occurs within a confined time window to minimize overall transmission time impact
Data Source
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AI summary
This closure relates to narrowband communication supporting an Internet of Things (IoT) service in a next-generation wireless communication system and, more particularly, to a method and apparatus for transmitting and receiving narrowband synchronization signals. A base station transmits an NB secondary synchronization signal (SSS) indicating N NB cell identities assigned for NB Internet of Things (IoT) operation, a specific sequence generated by multiplying a base sequence with a cover sequence in element units is used for the NB SSS, wherein the base sequence is generated through a second Zadoff-Chu sequence having a length corresponding to a largest prime number less than a length L in a frequency domain, and the specific sequence is divisionally mapped to and transmitted in a plurality of orthogonal frequency division multiplexing (OFDM) symbols in elements each having a length M.