Wideband Speech Coding for Half-Rate CDMA Interoperability

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Solution Overview

Problem

In CDMA wireless systems, the forced use of half-rate speech frames, especially during dim-and-burst signaling or bad channel conditions, leads to degraded speech performance due to inefficiencies in encoding onsets and transient signals, and interoperability issues with AMR-WB codecs, where forced half-rate frames are interpreted as erased frames.

Innovation Solution

Implementing a method to dynamically adjust bit rates by dropping specific signal-coding parameters, such as fixed codebook indices, to maintain full-rate operation while allowing for half-rate transmission in certain conditions, and introducing an interoperable half-rate mode that operates as full-rate by regenerating dropped parameters at the decoder, thereby improving robustness and interoperability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If half-rate speech frames are forced during dim-and-burst signaling or bad channel conditions, then system capacity is improved, but speech performance is degraded

Engineering Contradiction:

Improvesystem capacityVSAvoidspeech performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The system dynamically adjusts the coding rate based on channel conditions and signaling requirements. The speech coder can operate at full-rate or half-rate depending on whether dim-and-burst signaling is active, allowing optimal performance under varying conditions while maintaining good speech quality when capacity is constrained

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the bit rate parameter from fixed to variable, allowing the system to switch between full-rate and half-rate operation. This parameter change enables the system to achieve both high capacity (through half-rate) and good speech performance (through full-rate or optimized half-rate with proper parameter selection)

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If half-rate operation is imposed, then in-band signaling capability is improved, but encoding efficiency for onsets and transient signals is reduced

Engineering Contradiction:

Improvein-band signaling capabilityVSAvoidencoding efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The system dynamically selects between full-rate and half-rate modes based on the presence of dim-and-burst signaling requests. When signaling is required, the system transitions to half-rate mode to free up in-band capacity, while maintaining the ability to handle onsets and transients through proper mode selection and parameter optimization

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If forced half-rate frames are transmitted to AMR-WB codecs, then interoperability is attempted, but frame erasures occur

Engineering Contradiction:

ImproveinteroperabilityVSAvoidframe transmission reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an interoperability layer that acts as an intermediary between CDMA2000 and AMR-WB systems. This layer translates and adapts the bit stream format, ensuring that half-rate frames from CDMA2000 are properly formatted for AMR-WB decoding, thereby preventing frame erasures and enabling successful interoperability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the bit rate parameter to match the capabilities of the receiving codec. When interoperating with AMR-WB, the system adjusts the output bit rate and format parameters to be compatible with AMR-WB expectations, preventing the frame erasure problem that occurs with unadapted half-rate transmission

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8224657B2Method and device for efficient in-band dim-and-burst signaling and half-rate max operation in variable bit-rate wideband speech coding for CDMA wireless systems

Publication Date: 2012.07.17 NOKIA TECHNOLOGIES OY

AI summary

In the method and device for interoperating a first station using a first communication scheme and comprising a first coder and a first decoder with a second station using a second communication scheme and comprising a second coder and a second decoder, communication between the first and second stations is conducted by transmitting signal-coding parameters related to a sound signal from the coder of one of the first and second stations to the decoder of the other station. The sound signal is classified to determine whether the signal-coding parameters should be transmitted from the coder of one station to the decoder of the other station using a first communication mode in which full bit rate is used for transmission of the signal-coding parameters. When classification of the sound signal determines that the signal-coding parameters should be transmitted using the first communication mode and when a request to transmit the signal-coding parameters from the coder of one station to the decoder of the other station using a second communication mode designed to reduce bit rate during transmission of the signal-coding parameters is received, a portion of the signal-coding parameters from the coder one station is dropped and the remaining signal-coding parameters are transmitting to the decoder of the other station using the second communication mode. The dropped portion of the signal-coding parameters are regenerated before the decoder of the other station decodes the signal-coding parameters.