Alternating SACCH Transmissions for Dual SIM Collision Avoidance
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Solution Overview
Problem
In Dual SIM Dual Active (DSDA) mobile devices, the collision of Slow Associated Control Channel (SACCH) transmissions between an active and a held voice call leads to prioritization of the active call, resulting in missed measurement reports for the held call, causing increased handovers or call drops due to SACCH blanking.
Innovation Solution
The mobile device determines potential collisions between control channel transmissions for active and held calls and alternates or prioritizes them based on signal strength and quality thresholds to avoid collisions, ensuring both calls receive necessary measurement reports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SACCH transmission of the active call is always prioritized, then the active call control channel transmission is ensured, but the held call measurement reports are lost
Solution Approach 1:
The patent implements periodic action by alternating between transmitting SACCH for the active call and SACCH for the held call in different time periods. When the active call SACCH is transmitted in one period, the held call SACCH is transmitted in the next period, ensuring both calls receive periodic measurement report transmissions without permanent loss of information for either call.
2Productivity
If control channel transmissions for both calls are transmitted at the same time over one transmitter, then both calls can maintain active transmission, but transmission collision occurs
Solution Approach 1:
The patent applies segmentation by dividing the control channel transmissions into separate time segments for the active call and held call. Instead of attempting simultaneous transmission which causes collision, the single transmitter is segmented to transmit SACCH for one call in one time slot and SACCH for the other call in a different time slot, eliminating transmission collision while maintaining both call connections.
3Device complexity
If the BS does not receive measurement reports for the held call, then the device structure is simplified with one transmitter, but handovers or dropping of held calls increase
Solution Approach 1:
The patent implements preliminary action by proactively alternating the transmission timing of SACCH for the held call before collision occurs with the active call SACCH. The mobile device determines potential collision in advance and adjusts the held call SACCH transmission timing accordingly, ensuring measurement reports are transmitted successfully before handover decisions are triggered, thus maintaining held call stability without requiring additional transmitters.
Data Source
AI summary
Devices and methods are configured for resolving control channel transmission collision in a mobile device having first and second subscriptions (SUBs) when the first SUB is in an active voice call and the second SUB is in a held voice call. The devices and methods involve determining whether a control channel transmission of the first SUB would collide with a control channel transmission of the second SUB. In response to determining that the first SUB control channel transmission would collide with the second SUB control channel transmission, the devices and methods alternate the first SUB control channel transmission and the second SUB control channel transmission to avoid collision.