PRACH Design Using B-IFDMA for Unlicensed Spectrum
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Solution Overview
Problem
Current LTE systems face challenges in spectral efficiency and data rate enhancement due to the scarcity of licensed spectrum, particularly in the low frequency band, and require efficient operation in unlicensed spectrum to meet growing wireless traffic demands.
Innovation Solution
The implementation of a novel physical random access channel (PRACH) design using Block Interleaved Frequency Division Multiple Access (B-IFDMA) waveform and resource allocation strategies, including extended cyclic prefix duration, guard bands, and continuous resource block allocation, to satisfy occupied channel bandwidth regulations and reduce inter-interlace interference in both eLAA and MuLTEfire systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If interlaced resource blocks are used to satisfy occupied channel bandwidth regulations, then bandwidth occupancy requirements are met, but inter-interlace interference increases
Solution Approach 1:
Guard bands are introduced as intermediary elements between adjacent interlaces of resource blocks. These guard bands act as buffers that prevent direct interference between interlaces while maintaining the required occupied channel bandwidth. The guard bands are specifically designed to reduce inter-interlace interference in B-IFDMA waveforms without compromising bandwidth occupancy compliance.
Solution Approach 2:
The patent applies different quality characteristics to different parts of the frequency spectrum. Specifically, resource blocks within the same interlace maintain high quality for data transmission, while the regions between interlaces (guard bands) are designed with different properties to specifically address interference reduction. This local differentiation allows simultaneous optimization of bandwidth utilization and interference management.
2Measurement precision
If cyclic prefix duration is extended to reduce timing estimation ambiguity, then timing synchronization improves, but overhead increases
Solution Approach 1:
The patent segments the B-IFDMA waveform structure to incorporate specific features that aid timing estimation. By dividing the waveform into distinct components with known properties, the system can achieve accurate timing synchronization without requiring a uniformly extended cyclic prefix across the entire signal, thereby reducing overall overhead while maintaining precision.
3Adaptability or versatility
If B-IFDMA waveform is used to operate in unlicensed spectrum, then regulatory compliance is achieved, but spectral efficiency decreases
Solution Approach 1:
The patent optimizes various parameters of the B-IFDMA waveform to improve spectral efficiency while maintaining compliance with unlicensed spectrum regulations. This includes optimizing the spacing and configuration of resource blocks within interlaces, adjusting guard band dimensions, and fine-tuning cyclic prefix lengths. These parameter changes enable better spectral utilization without violating regulatory requirements for occupied channel bandwidth.
Data Source
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AI summary
Technology for an eNodeB operable to configure a physical random access channel (PRACH) to enable uplink communications by a user equipment (UE) is disclosed. The eNodeB can allocate a PRACH subframe configuration for a plurality of UEs that utilizes a Block Interleaved Frequency Division Multiple Access (B-IFDMA) subframe structure. The B-IFDMA subframe structure can comprise interlaced resource blocks (RBs) assigned to each of the plurality of UEs over a selected number of symbols. The eNodeB can decode a PRACH waveform received from one of the plurality of UEs. The UE can be configured to transmit the PRACH waveform using the PRACH subframe configuration.