Narrowband Synchronization Signal Sequence 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, particularly in reducing complexity and power consumption while maintaining effective cell identity indication and synchronization performance.
Innovation Solution
The method involves using specific sequences for NB-PSS and NB-SSS, such as Zadoff-Chu sequences and complementary Golay sequences, which are repeatedly transmitted over multiple OFDM symbols, and employing a combination of cyclic shifts and cover sequences to enhance correlation properties and reduce computational load, allowing for efficient cell identity indication and synchronization in NB-IoT systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Zadoff-Chu sequences and complementary Golay sequences are used for NB-PSS and NB-SSS, then synchronization performance and correlation properties are improved, but sequence length and computational complexity increase
Solution Approach 1:
The NB-SSS sequence is divided into two parts: a base sequence (complementary Golay sequence) and a cover sequence (Zadoff-Chu sequence). This segmentation allows the system to leverage the auto-correlation properties of Golay sequences for synchronization while using Zadoff-Chu sequences for cell identity indication, thereby improving overall synchronization performance without excessively increasing computational complexity.
Solution Approach 2:
The patent employs parameter changes by selecting specific root indices for Zadoff-Chu sequences and using different Golay sequence pairs to generate diverse NB-SSS sequences. This enables support for multiple cell identities (up to 168 different sequences) while maintaining manageable sequence lengths and computational requirements through optimized parameter selection.
2Adaptability or versatility
If multiple cell identities are supported through sequence combinations, then cell identity indication capability is improved, but sequence length and processing load increase
Solution Approach 1:
The cell identity indication is segmented into two components: the base sequence index (from complementary Golay sequences) and the cover sequence root index (from Zadoff-Chu sequences). This segmentation enables the system to indicate multiple cell identities through a combination of two smaller index sets rather than requiring a single large sequence set, thereby improving adaptability while reducing processing load.
Solution Approach 2:
The patent achieves multi-functionality by using the same NB-SSS structure to simultaneously provide synchronization information and cell identity indication. The complementary Golay sequences provide robust correlation for synchronization, while the Zadoff-Chu cover sequences provide orthogonal properties for distinguishing multiple cell identities, allowing a single sequence design to fulfill multiple functions efficiently.
3Reliability
If synchronization signals are repeatedly transmitted over multiple OFDM symbols, then synchronization reliability is improved, but transmission time and power consumption increase
Solution Approach 1:
The patent implements periodic action by transmitting the NB-PSS and NB-SSS sequences repeatedly across multiple OFDM symbols within a synchronization signal block. This periodic repetition enhances synchronization reliability through multiple correlation opportunities, while the structured periodic pattern allows receivers to efficiently accumulate correlation energy without requiring continuous high-power transmission.
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 a narrowband secondary synchronization signal indicating a narrowband cell identity, a specific sequence generated by performing phase rotation with respect to a base sequence generated through a second Zadoff-Chu sequence having a predetermined length L in a frequency domain and multiplying the base sequence by a cover sequence in element units is used for the narrowband secondary synchronization signal, and a specific root index is selected from among M (M<L) root indices as a root index of the second Zadoff-Chu sequence and the specific root index is selected in a range from k to k+M-1 in terms of a predetermined offset k.