DM-RS Broadcast Transmission Reducing Reference Signal Overhead
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Solution Overview
Problem
The existing LTE system faces challenges in efficiently transmitting broadcast information while maintaining low reference signal overhead and achieving high spectral efficiency, as it struggles with excessive reference signal overhead and reduced throughput due to the use of both CRS and DM-RS, which limits the ability to multiplex broadcast information with other channels effectively.
Innovation Solution
The solution involves using receiver-specific Demodulation Reference Signals (DM-RS) to support broadcast channel transmission, allowing the reuse of empty time-frequency resources for other channels, and defining antenna ports to enable efficient multiplexing of data/control information with broadcast information in the same subframe, thereby reducing reference signal overhead and improving spectral utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both CRS and DM-RS are used for broadcast information transmission, then channel estimation accuracy is improved, but reference signal overhead increases and spectral efficiency decreases
Solution Approach 1:
The patent extracts and removes the CRS from the broadcast information transmission scheme, retaining only DM-RS. This eliminates the conflict between CRS and DM-RS and reduces reference signal overhead while maintaining channel estimation accuracy through the use of DM-RS alone for demodulating broadcast channels.
Solution Approach 2:
The patent segments the reference signal functionality by dedicating DM-RS specifically to broadcast channel demodulation, separating it from the general-purpose CRS. This segmentation allows optimized resource allocation where DM-RS is transmitted only in resource blocks containing broadcast information, reducing overall overhead.
2Reliability
If broadcast information is transmitted using CRS, then coverage and robustness are improved, but the ability to multiplex with other channels is reduced
Solution Approach 1:
The patent introduces dynamic resource allocation for DM-RS, where the reference signals are transmitted only in resource blocks that actually contain broadcast information. This dynamic approach enables flexible multiplexing with other channels in the same subframe, as resource blocks without broadcast information can be fully allocated to other purposes without CRS overhead.
3Productivity
If DM-RS is used for broadcast channel transmission, then spectral efficiency is improved through better resource utilization, but receiver complexity increases
Solution Approach 1:
The patent configures DM-RS with receiver-specific parameters including scrambling IDs and orthogonal cover codes that enable receivers to self-identify and correlate with the appropriate reference signals. This self-service mechanism simplifies the receiver process by allowing direct correlation-based channel estimation without requiring complex blind detection of CRS parameters.
Data Source
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AI summary
Methods (700, 900) and nodes (110, 120) for transmission of broadcast information, over at least one antenna port, in a subframe, which transmission is received by a receiver (110) in a wireless communication system (100). The broadcast information is transmitted over a set of antenna ports comprising at least one antenna port, in at least one subframe (300) comprising a set of time-frequency resources, wherein a cell-specific reference signal, CRS, is not transmitted in each subframe (300). The method (700) comprises defining (701) a set of antenna ports for the set of time-frequency resources. Also, the method (700) comprises transmitting (702) the broadcast information on the defined (701) set of antenna ports, thereby using said set of time-frequency resources exclusively, such that they are unused for any other antenna port.