Hierarchical Modulation Constellation Design for Cooperative Multimedia
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Solution Overview
Problem
Current cooperative communication systems face limitations in improving the error rate of refinement bits while preserving the cooperative diversity gain of base bits, especially in multimedia transmission, and lack optimal constellation designs for source and relay nodes.
Innovation Solution
The method employs protection-level-exchanging modulation and optimal constellation diagram designs for source and relay nodes, using different hierarchical modulation constellations to enhance the bit error rate (BER) of refinement bits and maintain the cooperative diversity gain of base bits, by exchanging protection levels and rearranging constellation mappings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hierarchical modulation is used in cooperative communication, then the transmission structure is simple, but the bit error rate of refinement bits cannot be improved while preserving cooperative diversity gain of base bits
Solution Approach 1:
The patent applies protection-level-exchanging modulation where the relay node inverts the protection levels of base bits and refinement bits. Specifically, base bits are modulated with refinement protection level and refinement bits are modulated with base protection level, allowing the destination to achieve both cooperative diversity gain and improved refinement bit error rate through this inverted approach
Solution Approach 2:
The patent implements different hierarchical modulation constellation diagrams at different nodes: the source node uses one constellation diagram while the relay node uses a different constellation diagram with exchanged protection levels. This local differentiation allows each node to optimize its transmission for its specific role in the cooperative communication system
2Reliability
If standard constellation diagrams are used at source and relay nodes, then the system is easy to implement, but optimal reception performance cannot be achieved
Solution Approach 1:
The patent changes the modulation parameters by using different hierarchical modulation constellation diagrams at the source and relay nodes. The relay node specifically changes the protection level parameters through protection-level-exchanging modulation, optimizing the reception performance by adjusting these modulation parameters rather than using identical standard diagrams
3Reliability
If cooperative communication is implemented, then channel fading impact is mitigated, but bandwidth efficiency decreases due to extra transmission time slot
Solution Approach 1:
The patent combines cooperative communication with hierarchical modulation to merge the benefits of both approaches. By using protection-level-exchanging modulation, the system achieves cooperative diversity gain while optimizing bandwidth efficiency through the integrated modulation scheme that allows the relay to transmit information with exchanged protection levels rather than simply repeating the source signal
Data Source
AI summary
Provided is a cooperative multimedia communication system. The source node includes a first hierarchical modulation constellation diagram, modulates two data streams and transmits a first signal and a second signal. The relay node includes a protection-level-exchanging modulation and a second hierarchical modulation constellation diagram, modulates the second signal to generate a third signal and transmits the third signal. The destination node receives the first signal and the third signal and performs optimal decoding. The present disclosure designs a pair of optimal hierarchical constellation diagrams respectively for the source node and the relay node. Moreover, the present disclosure further provides a cooperative multimedia communication method.