RTP Header Compression UDP Checksum Elimination

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Solution Overview

Problem

Despite the use of robust header compression (RoHC) in VoIP over UMTS systems, there is still a significant overhead due to the transmission of dynamic fields in the RTP/UDP/IPv6 headers, particularly the UDP checksum, which is not fully compressible and is sent with every voice packet, limiting air interface capacity.

Innovation Solution

The proposed solution further compresses and decompresses dynamic fields in the RTP header, eliminates the UDP checksum, and optionally converts regular UDP to UDP-Lite, allowing for the removal of the RoHC header, thereby reducing overhead by eliminating unnecessary header components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If RoHC compression is applied to RTP/UDP/IPv6 headers, then header size is reduced from 656 bits to approximately 3 bytes, but the UDP checksum (2 bytes) remains uncompressible and must be transmitted with every packet

Engineering Contradiction:

Improveheader sizeVSAvoidair interface capacity

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent extracts and removes the UDP checksum field from the header compression process. By identifying that the checksum is the specific portion causing compression failure, the invention separates this field from the compressible header components, allowing the rest of the header to be fully compressed while the checksum is handled separately or eliminated through alternative error checking mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter of the UDP checksum by transitioning from mandatory checksum transmission to optional or eliminated checksum usage. This may involve switching to UDP-Lite with selective checksum coverage, using alternative error detection methods, or accepting higher error rates in exchange for complete header compression, thereby transforming the uncompressible checksum into a compressible or removable element.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the UDP checksum is transmitted with every voice packet, then error detection capability is maintained, but overhead increases and air interface capacity is limited

Engineering Contradiction:

Improveerror detectionVSAvoidair interface capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the checksum parameter by adopting UDP-Lite instead of standard UDP, which allows selective checksum coverage. The checksum can be applied only to critical portions of the packet rather than the entire packet, reducing the checksum size and enabling better compression while maintaining essential error detection capabilities for voice traffic.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial checksum coverage instead of complete checksum coverage. By using UDP-Lite with selective checksum fields, only the most critical parts of the packet are checksummed, providing sufficient error detection for voice applications while reducing overhead and enabling full header compression.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9031071B2Header elimination for real time internet applications

Publication Date: 2015.05.12 ALCATEL LUCENT SA

AI summary

The disclosed techniques provide for eliminating real-time transport protocol, RTP, extension bit X, marker bit M, time stamp and sequence number information and/or user data protocol, UDP, checksum information from the header of a packet for transmission.