Dynamic Frequency Hopping in OFDM Variable Bandwidth Systems
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Solution Overview
Problem
Frequency hopping techniques have not been effectively implemented in Orthogonal Frequency Division Multiplexing (OFDM) systems that employ variable bandwidth allocations, as the number of available hopping patterns changes with bandwidth allocations, and bandwidth allocations depend on instantaneous channel conditions, making it difficult to avoid collisions and optimize system efficiency.
Innovation Solution
A method that dynamically allocates subcarriers to mobile terminals based on their channel conditions and determines frequency hopping patterns 'on-the-fly' for each scheduling interval, signaling bandwidth allocations and frequency offsets in a scheduling grant to ensure efficient and flexible frequency hopping in OFDM systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency hopping patterns are established without consideration of bandwidth allocations, then collisions can be avoided, but system efficiency is reduced
Solution Approach 1:
The patent applies dynamics by making the frequency hopping pattern configurable and adaptable based on bandwidth allocation. The system transitions from static, pre-defined hopping patterns to dynamic patterns that are determined based on actual bandwidth allocations, allowing the system to optimize for both collision avoidance and efficiency under different operating conditions
Solution Approach 2:
The patent changes the parameter of frequency hopping pattern selection based on bandwidth allocation parameters. By making the hopping pattern dependent on the allocated bandwidth, the system can adapt its frequency hopping behavior to match the actual resource allocation, thereby improving system efficiency while maintaining collision avoidance through proper pattern selection
2Adaptability or versatility
If the number of available hopping patterns changes with bandwidth allocations, then frequency hopping can be adapted to variable bandwidth, but it becomes difficult to avoid collisions and optimize system efficiency
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple frequency hopping patterns that correspond to different bandwidth allocations. The network device selects the appropriate pre-defined pattern based on the allocated bandwidth, which simplifies the management complexity compared to dynamically generating patterns while maintaining adaptability to variable bandwidth requirements
Solution Approach 2:
The system dynamically selects from multiple pre-defined hopping patterns based on the actual bandwidth allocation. This dynamic selection mechanism allows the system to adapt to variable bandwidth while managing complexity through a finite set of pre-configured patterns rather than requiring complex real-time pattern generation
Data Source
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AI summary
Variable bandwidth assignment and frequency hopping are employed to make efficient use of radio resources. Variable bandwidth assignment is achieved by dynamically allocating different numbers of subcarriers to different mobile terminals depending on their instantaneous channel conditions. The frequency hopping patterns are determined "on-the-fly" based on the current bandwidth assignments. The bandwidth assignments and frequency hopping patterns are signaled to the mobile terminals in a scheduling grant.