Late Entry in Asynchronous Frequency Hopping Systems
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Solution Overview
Problem
In asynchronous frequency hopping systems, late entrants miss initial synchronization information, making it difficult for them to join ongoing communication sessions, and resending synchronization information using a different random hopping pattern struggles to maintain a pseudorandom frequency hopping pattern and equal frequency distribution as per FCC requirements.
Innovation Solution
A method and apparatus that generate a random permutation sequence of frequencies during the connection establishment phase, allowing late entrants to join by switching subsequent frequencies in the sequence to include synchronization frames, ensuring the hopping pattern remains pseudorandom and all frequencies are used equally, without affecting battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchronization information is resent using a different random hopping pattern, then late entrants can join the communication session, but the overall frequency hopping pattern cannot maintain pseudorandomness as per FCC requirements
Solution Approach 1:
The patent introduces a frequency indicator as an intermediary element that carries information about the hopping pattern without disrupting the pseudorandom sequence. This indicator acts as a mediator between the need for late entry synchronization and the requirement to maintain FCC-compliant pseudorandom hopping patterns, allowing late entrants to synchronize while the overall pattern remains compliant
Solution Approach 2:
The patent segments the synchronization information into separate frequency indicator fields that are embedded within the existing hopping framework. By dividing the synchronization task into discrete indicator segments rather than introducing a completely separate hopping pattern, the system enables late entry without compromising the overall pseudorandom pattern integrity
2Adaptability or versatility
If synchronization information is interleaved among traffic slots, then late entrants can receive it, but it is difficult to ensure equal frequency distribution as per FCC requirements
Solution Approach 1:
The patent changes the parameter representation by using frequency indicators that specify positions in the hopping sequence rather than directly transmitting synchronization on fixed frequencies. This parameter transformation allows the system to maintain uniform frequency distribution while providing synchronization opportunities for late entrants at appropriate points in the sequence
3Ease of operation
If PRE and SYNC are always on fixed, known frequencies, then receivers know what frequencies to listen to, but the hopping pattern loses randomness and FCC requirements are violated
Solution Approach 1:
The frequency indicator serves as an intermediary that provides the necessary frequency information to receivers without establishing fixed, known frequencies for PRE and SYNC. The indicator conveys the specific frequency position dynamically, maintaining both receiver operability and hopping pattern randomness required by FCC regulations
Data Source
AI summary
A wireless method and apparatus for late entry in frequency hopping systems that, during call setup, computes a random permutation sequence through a hop set of frequencies, chooses preamble frequencies to omit data thereon in lieu of preamble data, and swaps frequencies in the random permutation sequence such that synchronization frequencies lie next to the preamble frequencies with an expected delay such that late entrants can join. The wireless method and apparatus meets the FCC requirement of maintaining a pseudorandom hopping pattern and equal distribution of all frequencies in a hop set while guaranteeing late entry and having no effect on battery performance of radios.