Anchor MSCe Intersystem Handoff Codec Negotiation
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Solution Overview
Problem
Current intersystem handoff processes in mobile communication networks do not adequately address transcoding incompatibilities and suboptimal codec selections, leading to dropped calls and poor voice bearer path characteristics during handoffs between different Mobile Switching Centers (MSCs).
Innovation Solution
The implementation of an Anchor MSCe and Target MSCe configuration that sends Handoff Request messages with SIP INVITE messages containing TIA/EIA-41 FacilitiesDirective2 INVOKE messages, allowing for SDP offer/answer exchanges between the B-Party, Anchor MGW, and Target MGW to establish compatible codecs, ensuring transcoding capabilities meet pre-established criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intersystem handoff processes are used, then handoff speed is maintained at acceptable levels, but transcoding incompatibilities cause dropped calls and poor voice bearer path characteristics
Solution Approach 1:
The patent applies preliminary action by performing codec compatibility assessment and SDP offer/answer exchange during the handoff preparation phase before the actual handoff execution. The Anchor MSCe evaluates transcoding capabilities and establishes compatible codecs in advance, preventing dropped calls due to incompatibility while minimizing interruptions to voice service continuity.
2Manufacturing precision
If codec compatibility is thoroughly verified through SDP offer/answer exchange, then voice bearer path characteristics improve, but handoff processing complexity increases
Solution Approach 1:
The patent uses SDP (Session Description Protocol) as an intermediary mechanism that standardizes the codec negotiation process between Anchor MSCe and Target MSCe. The SDP offer/answer exchange acts as a structured intermediary protocol that simplifies the complex task of codec compatibility verification, enabling systematic comparison of transcoding capabilities while maintaining manageable procedure complexity.
3Reliability
If transcoding capabilities are fully utilized to match codecs, then voice quality improves, but the number of transcodings in the bearer path increases
Solution Approach 1:
The patent applies parameter changes by dynamically selecting and negotiating optimal codec parameters during the handoff process. The Anchor MSCe modifies codec selection based on real-time assessment of transcoding capabilities and network conditions, choosing parameters that maximize voice quality while minimizing the number of required transcodings in the bearer path.
Data Source
AI summary
An Anchor Mobile Switching Center emulation (MSCe) and a Target MSCe are described herein that take part in an intersystem handoff of a Mobile Station (MS) which is in communication with a B-party. Upon the MS establishing a connection with the Target MSCe, the Anchor MSCe may perform SDP offer/answer exchange between the Target network and the B-Party for the purpose of codec renegotiation to correct a transcoding incompatibility or to enhance the voice bearer path characteristics or to minimize the number of transcodings in the bearer path, between the two parties. The Anchor MSCe and the Target MSCe both support Advanced Legacy Mobile Station Domain (ALMSD) implying that only the SIP transport is used for intersystem handoff communications.