Composite Reference Signal Transmission in OFDM Symbols
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Solution Overview
Problem
Current communication networks face challenges in achieving efficient transmission and reception of reference signals, particularly in synchronization and beamforming, which affects performance and capacity, especially in high-frequency operations where propagation is more challenging.
Innovation Solution
The method involves transmitting a composite reference signal in a single OFDM symbol as a time domain concatenation of a first and a last reference signal, with a single cyclic prefix determined by the last part of the OFDM symbol, allowing for joint beamforming of multiple reference signals and reducing the time required for synchronization and beam finding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple reference signals are transmitted in separate OFDM symbols, then each signal can be transmitted with its own cyclic prefix, but the synchronization time increases and beam scanning efficiency decreases
Solution Approach 1:
The patent combines multiple reference signals (first reference signal and last reference signal) into a single composite reference signal transmitted within one OFDM symbol. This merging approach maintains the reliability of individual signal transmission while eliminating the time loss associated with transmitting multiple separate symbols, thereby reducing synchronization time and enabling faster beam scanning.
Solution Approach 2:
The patent transitions from transmitting reference signals in the time dimension (separate OFDM symbols) to transmitting them within the frequency dimension (single OFDM symbol with multiple frequency resources). This dimensional change allows multiple signals to coexist without temporal separation, achieving both reliability and time efficiency.
2Reliability
If multiple reference signals are transmitted in separate OFDM symbols, then each signal maintains its properties, but the number of transmission beams that can be scanned per time interval is reduced
Solution Approach 1:
By merging multiple reference signals into a composite signal within a single OFDM symbol, the system preserves the individual signal properties through frequency-domain separation while doubling the beam scanning capacity. This allows twice as many transmission beams to be scanned in each time interval compared to separate symbol transmission.
3Loss of time
If a composite reference signal is transmitted in a single OFDM symbol, then synchronization time is reduced and beam scanning efficiency is improved, but the cyclic prefix determination becomes more complex
Solution Approach 1:
The patent applies local quality by determining the cyclic prefix based specifically on the last part of the OFDM symbol (the last reference signal) rather than attempting to create a unified cyclic prefix for the entire composite signal. This localized approach simplifies the complexity while maintaining the time efficiency benefits of single-symbol transmission.
4Reliability
If reference signals are transmitted in multiple OFDM symbols, then frequency diversity is improved, but the single carrier properties are compromised
Solution Approach 1:
The patent achieves frequency diversity within the frequency dimension of a single OFDM symbol rather than across multiple time symbols. By allocating different frequency resources to different reference signals within the same symbol, the system maintains single carrier properties while still obtaining the benefits of frequency diversity for improved reliability.
Data Source
AI summary
There is provided mechanisms for transmitting reference signals. A method is performed by a first network device. The method comprises transmitting, in a single orthogonal frequency-division multiplexing (OFDM) symbol, a composite reference signal to a second network device. The composite reference signal is a time domain concatenation of at least a first reference signal and a last reference signal. The composite reference signal has a single cyclic prefix. The cyclic prefix is determined according to a last part of the single OFDM symbol. There is also provided mechanisms for receiving such reference signals.