Narrowband Reference Signal Scrambling Sequence Extension
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Solution Overview
Problem
In wireless communications systems, narrowband reference signals (NRS) from different cells can collide, causing interference and performance degradation due to their limited resource elements and periodic scrambling sequences, which are not effectively filtered out by user equipment (UE) due to their short sequence length.
Innovation Solution
The length of the NRS scrambling sequence for non-anchor carriers is extended from one radio frame to several radio frames, with the initialization equation adjusted to include the system frame number, allowing for increased initializations and improved interference rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the NRS scrambling sequence length is kept short (one radio frame), then the signaling overhead and processing complexity are reduced, but the interference rejection capability deteriorates due to inability to effectively filter out colliding signals from multiple cells
Solution Approach 1:
The patent applies dynamics by making the scrambling sequence initialization variable across multiple radio frames rather than static within a single frame. The initialization value changes dynamically from frame to frame, enabling the UE to distinguish between colliding NRS from different cells through the varying scrambling patterns, thus improving interference rejection while maintaining reasonable processing complexity.
2Reliability
If the NRS scrambling sequence length is extended to several radio frames, then the interference rejection capability is improved by enabling better filtering of colliding signals, but the signaling overhead and processing complexity increase
Solution Approach 1:
The patent segments the extended scrambling sequence into manageable portions across multiple radio frames. Rather than processing one extremely long sequence, the system divides it into frame-by-frame segments with incremental initialization values, allowing UEs to process interference rejection in manageable steps while still benefiting from the extended sequence length for better collision filtering.
3Ease of operation
If the NRS scrambling sequence initialization is based only on within-frame parameters, then the sequence length remains short and processing is simpler, but the ability to distinguish colliding NRS from multiple cells is insufficient
Solution Approach 1:
The patent adds another dimension to the scrambling sequence initialization by incorporating the radio frame number into the initialization equation. This transforms the initialization from a two-dimensional parameter (within-frame only) to a three-dimensional parameter (including frame number), providing additional differentiation capability for distinguishing colliding NRS from multiple cells while maintaining processing simplicity through the systematic extension approach.
Data Source
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AI summary
The described techniques relate to methods, systems, devices, and apparatuses that support narrowband reference signal (NRS) configuration for non-anchor carriers. Generally, the described techniques provide for increasing the length of an NRS scrambling sequence for non-anchor carriers. For example, the NRS scrambling sequence initialization equation may be a function of system frame number. A base station may transmit to a user equipment (UE) a non-anchor carrier configuration indicating that the NRS scrambling sequence is extended with respect to other NRS scrambling sequences. For example, the non-anchor carrier configuration may indicate the scrambling sequence initialization for the NRS. In some examples, the length of the NRS scrambling sequence is increased by extending the number of possible initializations. The base station and UE may communicate based on the extended length of the NRS scrambling sequence for non-anchor carriers of the NRS.