Adaptive Cyclic Prefix for OFDM Numerology Interference
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Solution Overview
Problem
In Orthogonal Frequency Division Multiplexing (OFDM) systems, asynchronous transmission and reception due to mismatched subcarrier spacing and propagation delays lead to interference issues, particularly in heterogeneous networks, affecting system performance and throughput.
Innovation Solution
A method and apparatus that generate signals with Reference Signals (RS) and messages by repeating them over OFDM symbols using a resource mapper, performing Inverse Fourier Transform, adding Cyclic Prefix, and adjusting power or beam directions to mitigate interference, allowing for asynchronous detection and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nodes use different subcarrier spacing (multiple numerologies) for transmission, then system adaptability and traffic flexibility are improved, but symbol boundary alignment deteriorates causing detection errors and interference
Solution Approach 1:
The patent applies local quality by making the cyclic prefix length adaptive to the specific numerology being used. Each node can configure its CP length according to its local numerology requirements (15kHz, 30kHz, 60kHz, etc.), allowing different parts of the network to operate with different numerologies while maintaining local synchronization integrity. This resolves the contradiction by enabling numerology diversity without forcing uniform symbol boundary alignment across all nodes.
Solution Approach 2:
The patent changes the parameter of cyclic prefix length dynamically based on the numerology configuration. By adjusting CP length as a variable parameter rather than a fixed value, the system can accommodate different subcarrier spacings and maintain reliable detection despite symbol boundary misalignment. This parameter adaptation allows the system to transition from static to dynamic numerology support.
2Area of stationary object
If nodes are geographically distributed over large distances, then network coverage area is improved, but propagation delay increases causing symbol boundary misalignment and interference
Solution Approach 1:
The patent introduces dynamics by making the cyclic prefix length configurable and adaptable rather than fixed. Nodes can dynamically adjust their CP length based on their propagation delay characteristics and numerology configuration. This dynamic adaptation allows the network to expand geographically while maintaining synchronization reliability through localized parameter optimization.
3Ease of operation
If traditional time-synchronous DL:UL ratio alignment is used across networks, then interference management is simplified, but network efficiency deteriorates due to inability to meet different traffic requirements of individual base stations
Solution Approach 1:
The patent segments the interference management approach by allowing individual base stations to independently configure their numerology and cyclic prefix parameters rather than enforcing a unified time-synchronous DL:UL ratio. This segmentation enables each BS to optimize its configuration for local traffic requirements while the overall system maintains interference coordination through the standardized CP-based synchronization mechanism.
Solution Approach 2:
The patent introduces dynamics by enabling flexible and independent configuration of numerology and cyclic prefix length at each base station. This dynamic capability allows the network to adapt to varying traffic conditions in real-time, with each BS can adjust its DL:UL ratio and numerology configuration independently to meet local demands, thereby improving overall network productivity while maintaining manageable interference through the standardized CP synchronization approach.
4Reliability
If additional guard time is added to mitigate BS-to-BS interference, then interference protection is improved, but system throughput deteriorates due to reduced available transmission time
Solution Approach 1:
The patent changes the parameter of cyclic prefix length to provide interference protection without requiring additional guard time beyond the standardized CP. By optimizing the CP length parameter based on numerology and propagation conditions, the system achieves interference mitigation as an inherent feature of the synchronization mechanism rather than as an additional overhead, thereby preserving system throughput.
Data Source
AI summary
Embodiments herein provides a method and apparatus for data communication in an OFDM system. The method comprising receiving by a second OFDM apparatus a plurality of parameters, a signal comprising data and at least one of a Reference Signal (RS) and a message from a first OFDM apparatus. The plurality of parameters comprises at least one of a numerology of the first apparatus, a numerology of the second apparatus, a ratio of numerology of the first apparatus to the second apparatus and a measurement window. The method includes filtering a desired band comprising the at least one of the RS and the message from the received signal, removing a cyclic prefix from the filtered signal, and decoding at least one of the RS and the message from the signal with adjusting a circular shift in the set of symbols based on the plurality of parameters.