Receiver Synchronization Using Zeroed Frequency Acquisition Sequences
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Solution Overview
Problem
Receiver synchronization in transmit diversity systems is inefficient due to interference and increased computational complexity, particularly when dealing with multiple transmitters, as existing methods either waste power, require lengthy acquisition times, or involve expensive algorithms.
Innovation Solution
Multiple transmitters simultaneously transmit orthogonal acquisition sequences with specific frequencies zeroed out, allowing receivers to filter and distinguish sequences based on zeroed frequencies, using delay and add filters and simplifying processing to achieve synchronization without increased complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmitters transmit synchronization signals simultaneously in transmit diversity systems, then data throughput and link range are improved, but the synchronization signals interfere with one another making receiver acquisition difficult
Solution Approach 1:
The patent segments the available frequency spectrum into distinct subsets, assigning each transmitter a unique frequency subset for its synchronization signal. This segmentation prevents interference between simultaneous transmissions from multiple transmitters while maintaining the diversity benefits of the system.
Solution Approach 2:
Each transmitter transmits with a specific local quality characteristic - a unique frequency signature or pattern that identifies it. This allows the receiver to distinguish between simultaneous signals from different transmitters by detecting their distinct local frequency characteristics.
2Ease of operation
If synchronization structures are transmitted from only a single antenna, then receiver acquisition is simplified, but diversity benefits are lost and transmitter power is wasted
Solution Approach 1:
The patent segments the transmission resources so that each antenna transmits a unique portion of the synchronization information on different frequencies. This allows the receiver to acquire signals from multiple antennas simultaneously without complex processing, while still benefiting from the diversity of multiple transmitters.
Solution Approach 2:
The synchronization structure is designed to serve multiple functions simultaneously: it provides acquisition information for the receiver, maintains diversity benefits across multiple transmitters, and enables the receiver to identify and synchronize with each transmitter individually through their unique frequency signatures.
3Reliability
If distinct pseudonoise structures are transmitted from each antenna with multiple correlators used to detect them, then synchronization is achieved, but computational complexity and processing cost increase significantly
Solution Approach 1:
The patent segments the detection process by frequency - the receiver uses a single correlator that processes signals in the frequency domain, separating the contributions from different transmitters based on their assigned frequency subsets. This avoids the need for multiple time-domain correlators and significantly reduces computational complexity.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple separate correlators in the time domain with a frequency-domain processing approach. By transforming the detection problem into the frequency domain, the system achieves the same synchronization reliability with a single correlator, reducing computational burden.
4Measurement precision
If orthogonal synchronization structures are transmitted from multiple antennas, then superior synchronization performance is achieved, but the approach is the most computationally expensive
Solution Approach 1:
The patent moves the orthogonality implementation from the time domain to the frequency dimension. By assigning different frequency subsets to different transmitters, the system achieves orthogonal separation without requiring complex time-domain orthogonal waveforms, thereby maintaining synchronization precision while reducing computational expense.
Data Source
AI summary
According to one or more embodiments, multiple transmitters may simultaneously transmit orthogonal acquisition sequences with certain frequencies zeroed out, such that receivers receiving a signal (waveform) may separate the signal into the orthogonal sequences based on which frequencies are zeroed out to perform acquisition processes. For example, each transmitter may simultaneously transmit an orthogonal acquisition sequence with certain tones zeroed out depending upon which transmitter transmits the symbol. A particular receiver may then receive a signal, and filter it to produce a plurality of filtered signals that distinguish orthogonal acquisition sequence symbols based on which tones are zeroed out within the symbols. The particular receiver may synchronize with a particular transmitter in response to detecting an orthogonal acquisition sequence within one of the filtered signals and correlating the detected sequence to the particular transmitter based on from which of the plurality of filtered signals the orthogonal acquisition sequence is detected.