Base Station Reference Signal Mapping for Demodulation Complexity
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Solution Overview
Problem
In LTE communication systems, user devices face increased complexity in demodulation processes due to multiple demodulation patterns required for signals transmitted using one, two, or four antennas, leading to inefficiencies in reception.
Innovation Solution
A base station configuration with multiple antennas, where reference signals for L1/L2 control channels and data channels are mapped within a predetermined number of basic time units at the beginning of each subframe, and additional reference signals are mapped to later time units, reducing the number of demodulation patterns needed at the user device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If reference signals for L1/L2 control channels and data channels are mapped to leading OFDM symbols in each transmission slot, then the transmission rate is improved, but the user device complexity increases due to multiple demodulation patterns
Solution Approach 1:
The patent segments the subframe into two distinct parts: the first part contains reference signals for L1/L2 control channels mapped to leading OFDM symbols, while the second part contains reference signals for data channels mapped to later OFDM symbols. This segmentation allows the user device to process control channel demodulation and data channel demodulation separately, reducing the need to evaluate multiple demodulation patterns simultaneously.
Solution Approach 2:
The patent performs preliminary mapping of reference signals for L1/L2 control channels to the beginning of the subframe (leading OFDM symbols) before mapping data channel reference signals. This preliminary action allows the user device to acquire control channel information first, which can then be used to configure the appropriate demodulation pattern for subsequent data channel processing, thereby reducing overall complexity.
2Adaptability or versatility
If multiple demodulation patterns are supported for different antenna configurations, then the adaptability is improved, but the reception efficiency deteriorates
Solution Approach 1:
The patent introduces dynamic signaling through downlink indicator bits that inform the user device about the antenna configuration and reference signal mapping pattern being used. This dynamic indication allows the system to adapt to different antenna configurations (1, 2, or 4 antennas) while guiding the user device to select the appropriate demodulation pattern, thereby maintaining adaptability without requiring the device to continuously evaluate all possible patterns.
Solution Approach 2:
The patent provides preliminary information about the transmission configuration through downlink indicator bits before the user device performs demodulation. This preliminary indication of the antenna configuration and reference signal mapping allows the user device to pre-configure the correct demodulation pattern, avoiding the need to try multiple patterns and thus improving reception efficiency while maintaining adaptability.
Data Source
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AI summary
A base station communicating with a user device using multiple antennas in a system where a subframe is composed of multiple slots each composed of multiple basic time units is disclosed. The base station includes a first mapping unit configured to map one or more reference signals used for demodulation of one or more L1/L2 control channels and one or more data channels to be transmitted from one or more of the antennas within a predetermined number of basic time units from the beginning of each subframe; and a second mapping unit configured to map reference signals used for demodulation of data channels to be transmitted from other ones of the antennas to one or more basic time units following the basic time units to which the reference signals used for demodulation of the L1/L2 control channels and the data channels are mapped.