QMF Voice Channel Multiplexing for Timeslot Reduction
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Solution Overview
Problem
Conventional systems face inefficiencies in allocating timeslots for both G.711 and G.722 voice channels, leading to resource consumption and reduced conferencing effectiveness due to incompatibility and the need for costly conversions.
Innovation Solution
Implementing a modified Quadrature Mirror Filter (QMF) within a PBX to separate and compress high-bandwidth and low-bandwidth voice signals, allowing for efficient distribution using a minimum number of timeslots while maintaining compatibility with G.711 equipment, by decomposing signals into high and low bands and using companding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional systems allocate timeslots to support both G.711 and G.722 talkers with conversion at a common device, then compatibility between different voice standards is achieved, but the number of timeslots consumed increases and system capacity is reduced
Solution Approach 1:
The patent segments the voice signal into high-bandwidth and low-bandwidth channels using a Quadrature Mirror Filter (QMF) before transmission. This allows G.722 signals to be split into components that can share timeslots with G.711 signals, reducing the total timeslot consumption while maintaining compatibility between different voice standards.
Solution Approach 2:
The patent introduces a frequency-domain dimension by separating voice signals into high and low bandwidth components. This dimensional separation enables efficient timeslot sharing between G.711 and G.722 channels, as the frequency components can be multiplexed together without requiring separate timeslots for each signal type.
2Adaptability or versatility
If G.722 channels are converted to G.711 for conferencing summation, then compatibility with G.711-optimized conferencing is maintained, but system capacity is reduced and conversion cost increases
Solution Approach 1:
Instead of converting entire G.722 signals to G.711, the patent segments the G.722 signal into high and low bandwidth components. The low-bandwidth component can be processed by G.711 conferencing systems while the high-bandwidth component is preserved, allowing partial compatibility without full conversion and thus maintaining higher system capacity.
Solution Approach 2:
The patent applies different processing qualities to different parts of the signal. The low-bandwidth portion is processed using G.711 compatibility methods for conferencing, while the high-bandwidth portion maintains its original quality. This local differentiation allows the system to maintain both compatibility and capacity without requiring complete signal conversion.
3Adaptability or versatility
If a maximum number of timeslots is allocated to support both voice standards at conversion devices, then both G.711 and G.722 channels can be transported, but precious resources are consumed and conferencing effectiveness is reduced
Solution Approach 1:
The patent merges the high and low bandwidth channels into a single timeslot structure using QMF decomposition. By combining these frequency components, the system can transport both G.711 and G.722 channels through fewer timeslots than would be required if separate timeslots were allocated for each signal type, thus reducing resource consumption while maintaining support for multiple voice standards.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces timeslot consumption and preserves conferencing capabilities, enabling seamless interoperability between G.722 and G.711 channels without the need for system-wide conversion, thus optimizing resource usage and maintaining existing investment in G.711 infrastructure.
Implementation Method 1
separating the input signal into a first low-bandwidth signal and a first high-bandwidth signal
Implementation Method 2
compressing the first low-bandwidth signal to provide a low-bandwidth channel
Implementation Method 3
the first compander expander portion receiving the low-bandwidth channel and producing a second low-band signal
Implementation Method 4
the converter compression portion receiving the first high-band signal and compressing the first high-band signal to produce a high-bandwidth channel
Implementation Method 5
the converter expander portion receiving the high-bandwidth channel and producing a second high-band signal
Implementation Method 6
the reconstruction portion of the QMF receives the second low-band signal and the second high-band signal and produces an output signal
Data Source
AI summary
A method and apparatus for distributing high-bandwidth and low-bandwidth voice channels is presented. An input signal is received and separated into a first low-band signal and a first high-band signal. The first low-band signal is compressed to provide a low-bandwidth channel and is used to carrying encoded voice signals (e.g. G.711). The high-band signal is also compressed to provide a high-bandwidth channel and is used to carry encoded voice signals (e.g. G.722).