Hierarchical Modulation for Control Channel User Data
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Solution Overview
Problem
Current wireless communication systems are limited by the static modulation order of control channels, which restricts spectral efficiency even in favorable conditions, as they cannot dynamically adapt to channel conditions due to complexity and robustness constraints.
Innovation Solution
Implementing hierarchical modulation to transmit both control and user data over a control channel, allowing control data to be demodulated at a lower, predefined order for robustness and user data at a higher order adaptable to current channel conditions, thereby maximizing spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control channel's modulation order is statically fixed to the most robust option to guarantee robustness against noise and interference, then the reliability of control data transmission is improved, but the spectral efficiency of the control channel deteriorates
Solution Approach 1:
The patent segments the control channel transmission into two distinct layers: a control data layer with fixed robust modulation (QPSK) and a user data layer with dynamically adaptable modulation orders. This segmentation allows each layer to be optimized independently - the control data layer maintains reliability through fixed robust modulation while the user data layer maximizes spectral efficiency through dynamic adaptation to channel conditions.
Solution Approach 2:
The patent introduces dynamics by allowing the user data modulation order to be dynamically adapted based on current channel conditions, while the control data modulation order remains static. The network can dynamically select from multiple modulation orders (e.g., QPSK, 16-QAM, 64-QAM, 256-QAM) for the user data layer, enabling the system to optimize spectral efficiency when channel conditions are favorable while maintaining robustness for control data.
2Productivity
If the control channel's modulation order is dynamically adapted to current channel conditions to maximize spectral efficiency, then the productivity of the control channel is improved, but the reliability of control data transmission deteriorates
Solution Approach 1:
The patent divides the transmitted signal into two independent modulation layers: one dedicated to control data with fixed robust modulation and another for user data with dynamic modulation adaptation. This segmentation ensures that dynamic adaptation for spectral efficiency does not compromise the reliability of control data, as each layer operates independently with its own modulation strategy.
Solution Approach 2:
The patent applies different modulation qualities to different parts of the transmitted data: control data receives the highest quality treatment with fixed robust modulation (QPSK) regardless of channel conditions, while user data receives adaptive modulation quality matched to current channel conditions. This local quality differentiation ensures control data reliability is never compromised while maximizing overall spectral efficiency.
3Productivity
If the modulation order for user data on the control channel is increased to maximize spectral efficiency, then the productivity is improved, but the device complexity for demodulation increases
Solution Approach 1:
The patent segments the demodulation process into two distinct stages: first demodulating the control data layer using simple fixed-order demodulation (QPSK), then demodulating the user data layer using the dynamically determined modulation order. This segmentation allows the device to handle high-order modulation for user data while maintaining simple, efficient demodulation for control data, reducing overall computational complexity compared to uniformly high-order demodulation.
Solution Approach 2:
The patent employs preliminary action by first demodulating and decoding the control data layer before proceeding to demodulate the user data layer. The control data contains information about the modulation order used for user data, so by first extracting this information from the control layer, the device can configure its demodulator appropriately for the user data layer, avoiding the need to support all possible modulation orders simultaneously and reducing overall complexity.
4Reliability
If separate channels are used for control data and user data, then the reliability of control data is improved, but the spectral efficiency deteriorates due to redundant resource allocation
Solution Approach 1:
The patent merges the control data channel and user data channel into a single multiplexed transmission over the control channel resources. By combining both data types in one channel with hierarchical modulation, the system eliminates the need for separate dedicated resources for control and user data, thereby improving resource utilization efficiency and spectral efficiency while maintaining the reliability benefits of separate processing through layer segmentation.
Solution Approach 2:
The patent makes the control channel universal by enabling it to carry both control data and user data simultaneously through hierarchical modulation. The control channel structure is designed to support multiple functions: transmitting control information for system operation and transmitting user data for communication payload, thereby eliminating the need for separate dedicated channels and improving overall resource efficiency.
Data Source
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AI summary
A wireless communication device (16A) is configured to receive user data from a radio network node (18) in a wireless communication system (10)that includes a data channel (26) over which user data is transmitted and a control channel (24) over which control data is transmitted. The device (16A) receives over the control channel (24) a hierarchically-modulated symbol (28) which conveys control data on a control-data modulation layer (30A) and conveys user data on a user-data modulation layer (30B). The control-data modulation layer (30A) is recoverable via demodulation at a lower order, and the user-data modulation layer (30B) is recoverable via demodulation at a higher order. The lower order is lower than the higher order and is generally predefined independent of conditions on the control channel (24). The device (16A) recovers the user data received over the control channel (24) by demodulating at least the user-data modulation layer (30B) at the higher order.