Precoder Cycling for Wireless Signal Diversity
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Solution Overview
Problem
In LTE and LTE-A systems, the rapid changes in channel environments often lead to inaccurate channel state information (CSI), resulting in reduced received signal quality and data transmission reliability due to the inability to obtain a precise precoding matrix.
Innovation Solution
The implementation of a data sending method that performs transmit diversity preprocessing and precoder cycling, using multiple precoding vectors for each transmit diversity spatial stream across different time-frequency resources to achieve spatial and time-frequency diversity gains, thereby improving signal quality and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precoding technology is used to improve channel transmission, then signal quality can be improved, but when channel state information cannot be obtained due to rapid channel changes, the precoding matrix becomes inaccurate and received signal quality deteriorates
Solution Approach 1:
The patent applies dynamics by making the precoding matrix time-varying through precoder cycling. Instead of using a fixed precoding matrix that becomes inaccurate when channel changes rapidly, the system dynamically switches between multiple precoding matrices (precoders) across different time slots or frequency resources. This dynamic adaptation allows the system to maintain transmission reliability even when channel state information is unavailable or inaccurate, as the cycling precoders can track channel variations without requiring precise real-time CSI.
Solution Approach 2:
The patent implements periodic action through precoder cycling, where multiple precoding matrices are cycled periodically across time-frequency resources. The system uses a codebook containing multiple precoders and selects different precoders for different resource blocks or time slots in a cyclic manner. This periodic switching provides diversity gain and robustness against rapid channel changes, effectively resolving the contradiction between maintaining accurate precoding and adapting to rapidly changing channels without requiring precise real-time channel state information.
2Ease of operation
If a single precoding matrix is used for data transmission, then the transmission process is simple, but when channel environment changes rapidly, the received signal quality deteriorates due to mismatch with current channel conditions
Solution Approach 1:
The patent transforms the static single-precoder system into a dynamic multi-precoder cycling system. While maintaining operational simplicity through automated cycling based on predefined codebooks, the system achieves enhanced reliability by dynamically adapting to channel changes. The precoder cycling mechanism automatically switches between multiple precoders without complex real-time optimization, resolving the contradiction between operational simplicity and signal quality reliability.
3Reliability
If transmit diversity preprocessing is performed to obtain spatial diversity gain, then received signal quality improves, but the system complexity increases due to additional processing steps
Solution Approach 1:
The patent merges transmit diversity preprocessing with precoder cycling into a unified transmission framework. Instead of treating diversity processing and precoding as separate complex stages, the system combines them by applying diversity techniques within the context of cyclic precoding across time-frequency resources. This integration achieves spatial diversity gain while managing system complexity through coordinated operation of diversity modules and precoder cycling mechanisms.
Data Source
AI summary
This application provides a data sending method, a data receiving method, a network device, and a terminal device, to obtain a diversity gain to a greater extent, improve received signal quality, and improve data transmission reliability. The method includes: performing, by a network device, transmit diversity preprocessing on one modulated symbol stream to obtain at least one transmit diversity spatial stream; performing, by the network device, precoder cycling on the at least one transmit diversity spatial stream to obtain at least one precoded data stream, where each of the at least one transmit diversity spatial stream corresponds to at least two different precoding vectors; and sending, by the network device, the at least one precoded data stream to a first terminal device.