Non-orthogonal Superposition for MBMS Spectral Efficiency
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Solution Overview
Problem
Conventional 3GPP LTE systems face limitations in spectral efficiency and interference management due to orthogonal multiplexing, particularly in multimedia broadcast multicast services (MBMS), where users with varying propagation losses receive signals with suboptimal modulation and power allocation, leading to inefficient resource utilization and interference.
Innovation Solution
Implementing multiuser non-orthogonal superposition transmissions at eNodeBs, where multiple physical multicast channels with different modulation and coding schemes are multiplexed and transmitted using partially or fully overlapping physical resource blocks, with power offset parameters and scrambling identities sent to UEs to enable efficient decoding and interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If orthogonal multiplexing is used in conventional 3GPP LTE systems, then interference management is simplified, but spectral efficiency deteriorates
Solution Approach 1:
The patent merges multiple physical multicast channels with different modulation and coding schemes into a single aggregate PMCH signal, allowing multiple users to share the same time-frequency resources through non-orthogonal multiplexing. This combining approach improves spectral efficiency while managing interference through superposition coding.
Solution Approach 2:
The patent transitions from orthogonal frequency-division multiplexing to non-orthogonal multiplexing by adding a power domain dimension. Different users are separated not by frequency or time but by power levels, allowing closer UEs to receive higher-order signals and farther UEs to receive lower-order signals simultaneously on the same resources.
2Device complexity
If single modulation and coding scheme is used for all users, then system complexity is reduced, but spectral efficiency deteriorates
Solution Approach 1:
The patent applies different modulation and coding schemes to different users based on their specific channel conditions. Each user receives a customized MCS tailored to their propagation loss characteristics, with closer UEs getting higher-order modulations and farther UEs getting more robust lower-order modulations, thereby optimizing spectral efficiency for each local user.
Solution Approach 2:
The system dynamically assigns different modulation and coding schemes to multiple users within the same cell based on their varying channel conditions. The eNodeB can adaptively adjust the MCS for each user in real-time, allowing the system to respond to changing propagation conditions and maximize overall spectral efficiency.
3Productivity
If non-orthogonal superposition transmissions are implemented, then spectral efficiency is improved, but decoding complexity at UE increases
Solution Approach 1:
The eNodeB performs preliminary actions by pre-signaling power offset parameters, scrambling identities, and modulation and coding schemes to UEs before the actual data transmission. This advance provision of decoding parameters enables UEs to efficiently decode the aggregate PMCH signal without having to perform complex blind searches or iterative decoding procedures.
Solution Approach 2:
The system implements feedback mechanisms where UEs report their channel conditions and reception status to the eNodeB. Based on this feedback, the eNodeB adjusts the power offset parameters and MCS assignments to optimize the superposition coding scheme, balancing spectral efficiency gains with UE decoding complexity.
Data Source
AI summary
Technology for an eNodeB operable to perform multiuser non-orthogonal superposition transmissions for multimedia broadcast multicast service (MBMS) is disclosed. The eNodeB can modulate a first physical multicast channel (PMCH) signal for MBMS with a first modulation and coding scheme (MCS). The eNodeB can modulate a second PMCH signal for MBMS with a second MCS. The eNodeB can multiplex the first PMCH signal and the second PMCH signal to form an aggregate PMCH signal. The eNodeB can transmit the aggregate PMCH signal to a plurality of UEs using multiuser non-orthogonal superposition for MBMS, wherein the first PMCH signal in the aggregate PMCH signal is transmitted using physical resource blocks (PRBs) that are partially or fully overlapped in time and frequency with PRBs of the second PMCH signal in the aggregate PMCH signal.