Synchronizing Wireless Network Logic Entities
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Solution Overview
Problem
In wireless communication networks, handovers between unsynchronized radio access logic entities lead to temporary disruptions or degradations in broadcast and multicast services due to differences in packet reception timing across entities, resulting in lost or duplicate packets during handovers.
Innovation Solution
A method and device for synchronizing radio access logic entities by estimating the time difference in packet reception across entities within a synchronization area, allowing each entity to wait before retransmitting packets to ensure synchronized delivery, using a reference clock to determine the correct timing for retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receivers are equipped to synchronize local clocks of logic entities, then synchronization precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a synchronization manager as an intermediary component that coordinates packet transmissions between logic entities. Instead of each entity independently synchronizing via GPS, the manager receives packets from entities, determines their reception times, and controls retransmission timing to achieve synchronization without requiring GPS equipment at each entity.
Solution Approach 2:
The patent uses timing information copying and propagation. The synchronization manager collects reception time data from multiple logic entities, processes this timing information, and distributes synchronization control decisions back to entities. This copying of timing data enables synchronization without direct GPS connection at each entity.
2Device complexity
If logic entities operate with independent local clocks, then device complexity is reduced, but service reliability deteriorates during handovers due to packet loss and duplication
Solution Approach 1:
The synchronization manager performs preliminary timing analysis by collecting packet reception times from all logic entities before coordinating their retransmissions. By determining the timing relationships in advance and preparing synchronization decisions, the system ensures reliable handovers without requiring complex real-time synchronization mechanisms at each entity.
Solution Approach 2:
The system implements feedback loops where logic entities report their packet reception times to the synchronization manager, which then adjusts retransmission timing based on this feedback. This closed-loop control ensures that packets are retransmitted in a synchronized manner, preventing loss and duplication during handovers while keeping individual entity complexity low.
Data Source
AI summary
A device (D) is dedicated to synchronizing radio access logic entitles (EL1-EL3) each having a local clock and forming part of a wireless communication network capable of broadcasting and/or multicasting content-defining data packets between a broadcast and/or multicast source (SD) and mobile communication terminals, via logic entities. This device (D) comprises calculation means (MC) tasked with i) estimating, for each logic entity (EL1-EL3) of a synchronization area (ZS) of the network, the time (HRRk), with respect to a reference clock (CR) when said entity received a selected packet from the broadcast and/or multicast source (SD), then ii) determining, for each logic entity, a value (Vk) that represents the time difference between its reception time (HRRk) and the latest reception time (HRRk) among those of the logic entities, and iii) ordering each logic entity to wait for a period of time equal to the value (Vk) which was determined for it before retransmitting each packet received from the broadcast and/or multicast source (SD) to the terminals (MS) located within its synchronization area (ZS).