VoIP Packet Discarding for Bandwidth Efficiency in CDMA2000
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Solution Overview
Problem
In VoIP services over CDMA2000 1xEV-DV systems, the transmission of VoIP packets is inefficient due to a large portion of bandwidth being wasted on encoding background noise, which adversely affects bandwidth usage and voice quality.
Innovation Solution
The method involves identifying and discarding VoIP packets that encode background noise, while performing header compression on the remaining packets to efficiently transmit them over wireless links, thereby optimizing bandwidth usage and improving voice quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rate 1/8 VoIP packets are transmitted on the F-PDCH, then bandwidth utilization is improved, but voice quality deteriorates due to transmission of background noise
Solution Approach 1:
The patent extracts and removes rate 1/8 VoIP packets that encode background noise from the transmission stream. By identifying and discarding these packets before transmission, the system eliminates useless data that wastes bandwidth, while retaining only rate 1 and rate 1/2 packets that encode intelligible speech, thus improving both bandwidth utilization and voice quality.
2Productivity
If many rate 1/8 VoIP packets are bundled into one encoder packet, then packing efficiency is improved, but end-to-end delay increases and voice quality deteriorates
Solution Approach 1:
The patent extracts rate 1/8 packets before bundling, removing the source of the problem. By discarding these low-rate packets upfront, the system avoids the need to bundle them with higher-rate packets, thereby preventing the delay and quality degradation that would result from such bundling while still achieving improved packing efficiency with the remaining packets.
3Loss of information
If background noise packets are transmitted, then speech completeness is maintained, but bandwidth is wasted on uninformative data
Solution Approach 1:
The patent extracts and removes packets encoding background noise, which by definition contain little or no useful speech information. This extraction process maintains speech completeness by retaining only packets with intelligible speech (rate 1 and rate 1/2), while eliminating the bandwidth waste associated with transmitting uninformative background noise data.
Data Source
AI summary
The present invention concerns methods for efficiently supporting Voice over Internet Protocol (VoIP) on the Forward Packet Data Channel (F-PDCH) in CDMA 2000 1xEV-DV systems. Active speech in VoIP is encoded using, for example enhanced variable rate codec (EVRC), which produces 171, 80 and 16 bits per 20 ms of speech for Rate 1, Rate ½ and Rate ⅛, respectively. However, about 60% of the time a user is inactive during a speech session, so an inordinate amount of system bandwidth is comprised of rate ⅛ VoIP packets. In one embodiment of the present invention the apparatus of the present invention identifies the Rate ⅛ voice frame packets and discards them. In another embodiment of the present invention, the apparatus of the present invention identifies the Rate ⅛ voice frame packets and selects some of them for further transmission. In both embodiments the efficiency of channel utilization is increased since the amount of channel band width used to communicate relatively little information, e.g., gaps of silence, is decreased.