LTE downlink: synchronization signals (2022)
13 hours ago
- #Synchronization
- #LTE
- #Signal Analysis
- Analysis of LTE downlink signals focusing on Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS).
- PSS is transmitted in the last symbol of slots 0 and 10 in each radio frame in FDD systems.
- SSS is transmitted on the symbol before the PSS and occupies the central 6 resource blocks (1.08 MHz).
- PBCH follows PSS and SSS transmissions, occupying all 72 subcarriers in the central 6 resource blocks.
- Recording setup involved driving around to locate the base station for strong line-of-sight signals.
- The cell uses Vodafone’s 10 MHz carrier at 806 MHz in the B20 band with PCI 378.
- PSS structure involves Zadoff-Chu sequences of length 63, with three possible sequences based on cell ID.
- SSS structure uses BPSK modulation and interleaved sequences derived from M-sequences.
- Detection of PSS and SSS involves correlation techniques to identify cell identity and synchronization.
- Analysis includes equalization, channel response estimation, and group delay correction.
- Beamforming effects observed in PSS transmissions with varying power levels across different beams.
- Cross-correlation issues noted between PSS sequences for different cell IDs.
- SSS detection used to confirm cell group number and achieve frame synchronization.
- Techniques to separate and analyze weaker signals from neighboring cells (PCI 378 and 379).
- Observations on synchronization differences between Orange, Vodafone, and Movistar cells.
- Use of Jupyter notebooks for signal processing and visualization of LTE signals.