Multicarrier Subband Allocation for QoS Prioritization
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Solution Overview
Problem
Multicarrier modulation communications systems, such as ADSL, cannot differentiate in quality of service (QoS) among various streams due to uniform noise margins, necessitating a method to prioritize QoS for specific streams like VoIP or videoconference services over others like Internet or digital television.
Innovation Solution
A method that associates each subband with a normalized signal-to-noise ratio, allocates bits based on this classification, and adjusts noise margins to prioritize preferred streams, ensuring higher QoS while minimizing bit rate loss by distributing remaining capacity pro rata among non-preferred streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform noise margins are applied to all streams, then the system is simple to operate, but quality of service cannot be differentiated among various streams
Solution Approach 1:
The patent applies different noise margins to different streams based on their service requirements. Preferred streams (e.g., VoIP, videoconference) receive higher noise margins for better quality of service, while non-preferred streams (e.g., Internet, digital television) receive lower noise margins. This local differentiation resolves the contradiction by enabling QoS differentiation while maintaining operational simplicity through automated classification and allocation.
2Reliability
If higher noise margins are assigned to preferred streams, then quality of service for those streams is enhanced, but bit rate loss increases
Solution Approach 1:
The patent dynamically adjusts the noise margin parameter based on stream classification and service requirements. By changing the noise margin parameter selectively for different streams rather than uniformly, the system enhances QoS for preferred streams while minimizing overall bit rate loss. The automated allocation algorithm optimizes the balance between noise margin and bit rate efficiency.
3Adaptability or versatility
If automated allocation algorithms are implemented to differentiate QoS, then quality of service prioritization is achieved, but device complexity increases
Solution Approach 1:
The patent implements preliminary classification of streams into preferred and non-preferred categories based on service type before the actual bit and noise margin allocation process. This preliminary action simplifies the subsequent automated allocation by pre-organizing streams according to their QoS requirements, reducing the complexity of the allocation algorithm while maintaining effective QoS prioritization.
Data Source
AI summary
A method of allocating a plurality of subbands to a plurality of streams of a multichannel link in a multicarrier modulation communications system, each stream being successively defined in a communications frame of said multichannel link by a number Mj of bits to be transmitted and a noise margin Γj. Each subband is associated with a normalized signal-to-noise ratio on the multichannel link. The subbands are classified in a specific order of the normalized signal-to-noise ratios. An energy Ei per subband is determined by a binary allocation algorithm. For each stream taken in the order of said frame, a number Nj of consecutive subbands taken in the order of normalized signal-to-noise ratios is allocated so that the sum of the numbers nij of bits in each subband allocated to each stream is equal to Mj where:Mj=∑i=1Njnijand nij=log2(1+El·(SNR0)i/ΓJ).