Hierarchical Preamble Structure for Wireless Receiver Power Reduction
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Solution Overview
Problem
Existing wireless communications systems face challenges in reducing power consumption and preamble detection time while maintaining effective transmission and avoiding interference between multiple piconets, which can lead to missed calls or messages and increased packet error rates.
Innovation Solution
A system and method that uses a hierarchical preamble structure, where each piconet transmits a unique code sequence, allowing for efficient preamble detection and reduced power consumption by concatenating sub-sequences with varying numbers of zeroes, and employing a two-stage despreading process to decode received signals, enabling better identification of transmission sources and reducing false locks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the preamble is shortened to reduce receiver on-time and power consumption, then power consumption is reduced, but the transmission is more easily missed by the receiver
Solution Approach 1:
The preamble is segmented into multiple sub-sequences, each with a specific number of zeroes, arranged in a hierarchical structure. This segmentation allows the preamble to be both short and highly detectable, as the structured pattern enables reliable detection even with reduced overall length.
Solution Approach 2:
The hierarchical preamble structure is designed in advance with specific patterns of zeroes and sub-sequences that facilitate easy detection. The preliminary design of this structured pattern ensures that receivers can quickly and reliably detect the transmission start, compensating for the reduced preamble length.
2Loss of time
If the preamble is shortened to reduce air-time, then receiver on-time is reduced, but existing advantages of wireless communications techniques cannot be fully exploited
Solution Approach 1:
The preamble structure transitions from a simple time-domain sequence to a hierarchical structure with multiple dimensions (sub-sequences, zeroes, positions). This dimensional complexity allows the short preamble to carry more information and enable full exploitation of bandwidth and frequency diversity advantages.
Solution Approach 2:
The hierarchical preamble uses variable parameters including different numbers of zeroes in each sub-sequence, different sub-sequence positions, and unique code sequences for different piconets. These parameter variations allow the short preamble to maintain adaptability for bandwidth utilization, frequency diversity, and interference management.
3Productivity
If multiple piconets operate in close proximity, then network density is increased, but interference between piconets occurs leading to false locks
Solution Approach 1:
Each piconet is assigned a unique local quality in the form of a distinctive code sequence within the hierarchical preamble structure. This local differentiation allows receivers to identify and lock onto the correct piconet signal even when multiple piconets operate simultaneously in close proximity, preventing false locks.
Solution Approach 2:
The unique code sequences are assigned to different piconets in advance, enabling preliminary differentiation before transmission. When multiple piconets operate concurrently, receivers can use these pre-assigned unique sequences to quickly identify the intended piconet and avoid false locks on interfering signals.
Data Source
AI summary
System and method for simplifying preamble detection and reducing power consumption in receivers. A preferred embodiment comprises a preamble made up of two sequences, a first sequence that is specified in the time domain and a second sequence that is specified in the frequency domain. The first sequence which comprises multiple copies of a time domain code sequence can allow easy detection of the preamble while the second sequence comprises multiple copies of a frequency domain code sequence and allows easy determination of the frequency response of the communications channel. A hierarchical sequence can be used to allow multi-stage correlation. This can result in a less complex correlator, hence lower power consumption. Piconets can use different code sequences to allow rapid determination of the source of a transmission without requiring the receiver to decode the entire transmission.