DECT Beacon Signal Redundancy for Collision Avoidance
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Solution Overview
Problem
In DECT wireless communication networks, occultation and collision of beacon signals between multiple networks can occur due to uncoordinated carrier frequencies and time slots, leading to communication losses, which are critical in applications like rescue operations and industrial trials.
Innovation Solution
A wireless digital communication method where the main station transmits a beacon signal in a first time slot, and it is retransmitted by the secondary station in a subsequent downlink time slot, potentially on a different carrier frequency, to reduce occultation and collision risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple DECT networks transmit beacon signals simultaneously on the same carrier frequency and time slot, then network coverage and connectivity are improved, but signal occultation and collision occur leading to communication loss
Solution Approach 1:
The beacon signal is transmitted periodically at multiple predefined time positions within a frame structure. Each network transmits beacons at specific periodic intervals (e.g., time positions 0, 4, 8, 12) rather than continuously, which when combined with frequency hopping, distributes transmissions across different time-frequency resources to avoid permanent occultation.
Solution Approach 2:
The system employs dynamic frequency hopping where the carrier frequency changes over time according to a predefined sequence. The beacon transmission frequency is not static but evolves through multiple frequency slots, allowing networks to dynamically avoid frequency conflicts and reducing the probability of sustained signal occultation between neighboring networks.
2Productivity
If beacon signals are transmitted on the same time slot and carrier frequency, then transmission efficiency is improved, but signal collision occurs causing mobile stations to lose network connectivity
Solution Approach 1:
The transmission resource is segmented into multiple time positions within a frame (e.g., positions 0, 4, 8, 12) and multiple frequency slots. Instead of using a single time-frequency resource, the beacon signal is divided across several segmented positions, so that even if one segment collides, other segments remain available for reception.
Solution Approach 2:
The system transitions from a single-dimension (single time slot) transmission to a multi-dimensional resource allocation spanning both time (multiple positions within frame) and frequency (multiple slots). This dimensional expansion allows efficient use of resources while providing redundancy against collisions in any single dimension.
3Reliability
If additional transmission/reception means are added to prevent beacon signal occultation, then communication reliability is improved, but equipment complexity and weight increase
Solution Approach 1:
Instead of adding physical redundancy (duplicate hardware systems), the invention creates virtual copies of the beacon transmission at multiple time positions and frequencies. The same beacon information is copied and transmitted across different resource positions, providing redundancy through signal replication rather than hardware duplication.
Solution Approach 2:
The existing DECT transmission infrastructure is made multi-functional by utilizing it for both data communication and beacon signaling across multiple time-frequency resources. The same radio frequency interface and baseband processing handle both regular traffic and beacon transmissions, eliminating the need for separate dedicated hardware for beacon functions.
Data Source
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AI summary
Cordless digital communication method complying with a standard based on TDMA mode access for a star network comprising a base unit (FP1) and at least one mobile unit (MP2), the communication using a time-division duplex mode implementing a plurality of frames each comprising downlink (Tx) timeslots followed by uplink (Rx) timeslots, transmission being carried out at a carrier frequency chosen from a set number of carrier frequencies, the method comprising the following steps: transmission, by the base unit (MP1), in a first downlink (Tx) timeslot (IT0), of a pilot signal (15); and transmission, by the base unit (MP1), in a second downlink (Tx) timeslot (IT5) of the same frame, of a repetition of the pilot signal (15').