Heterogeneous Network Node Toggling Transmission Layers
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Solution Overview
Problem
In heterogeneous wireless communication networks, inter-cell interference and varying channel conditions lead to differing error rates for code words transmitted over multiple layers, making it challenging to maintain a common modulation and coding scheme and achieving target block error rates.
Innovation Solution
The method involves toggling code word to transmission layer mappings in alternating transmissions, allowing network nodes to determine a common downlink modulation and coding scheme and ensuring target block error rates by adjusting transmission parameters based on channel conditions and interference levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple code words are transmitted over multiple layers in a heterogeneous network, then spectral efficiency is improved, but inter-cell interference causes differing error rates for each code word
Solution Approach 1:
The patent applies periodic action by alternating the mapping of code words to transmission layers in a periodic manner. Specifically, in even subframes the first code word is mapped to the first transmission layer and the second code word to the second transmission layer, while in odd subframes this mapping is swapped. This periodic alternation allows the system to maintain high spectral efficiency through multi-layer transmission while ensuring that both code words experience similar interference conditions over time, thereby achieving consistent block error rates
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the code word to transmission layer mapping based on subframe index parity. The mapping parameters are changed periodically between even and odd subframes, allowing the system to adapt to varying channel conditions and interference patterns while maintaining overall performance consistency. This parameter adjustment enables the system to achieve both high spectral efficiency and reliable error rate performance
2Device complexity
If a common modulation and coding scheme is used for multiple code words, then system complexity is reduced, but varying channel conditions and interference make it difficult to achieve target block error rates
Solution Approach 1:
The patent uses parameter changes by alternating the code word to transmission layer mapping based on subframe parity (even/odd subframes). This simple parameter adjustment allows a single common modulation and coding scheme to effectively serve multiple code words under varying channel conditions. By periodically swapping which code word is transmitted on which layer, the system maintains low complexity while ensuring that both code words achieve the target block error rate over time
Data Source
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AI summary
According to certain embodiments, methods and systems for toggling transmission parameters in a heterogeneous network to achieve a target block error rate by a network node may include obtaining a signal-to-noise ratio (SINR) estimate from channel quality information for a downlink between a network node and a wireless device. For each of a first code word and a second code word to be transmitted on the downlink, a block error rate estimate may be obtained based on the SINR estimate. The network node may then determine at least one expected SINR for the first code word and the second code word. The at least one expected SINR may be determined as a function of the SINR estimate and the block error rate estimate. Based on the at least one expected SINR for the first code word and the second code word, a modulation and coding scheme (MCS) for obtaining a target block error rate may be selected. The network node may then transmit the first code word on a first transmission layer and the second code word on a second transmission layer during a first transmission time interval. In a second transmission time interval, the network node may transmit the first code word on the second transmission layer and the second code word on the first transmission layer.