GSM Packet Synchronization Over Discontinuous IP Networks

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Solution Overview

Problem

GSM systems face challenges in maintaining synchronization requirements over unsynchronized networks like the Internet, leading to discontinuities and session resets, especially when traditional point-to-point links are replaced with unreliable IP networks.

Innovation Solution

Incorporating synchronizers in small-scale BTS and AGW devices to process and manage packets, ensuring synchronization by generating replacement data and buffering to maintain consistent packet transmission rates, thus adhering to Abis and Air interface protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional point-to-point links are replaced with IP-based networks to improve flexibility and support Internet communication, then network adaptability and versatility are improved, but synchronization reliability deteriorates due to discontinuous packet delivery

Engineering Contradiction:

Improvenetwork adaptabilityVSAvoidsynchronization reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces synchronizer components (212, 214) as intermediary devices between the IP network and GSM interfaces. These synchronizers receive discontinuous IP packets, buffer them, and retransmit them at synchronized rates required by GSM protocols, thereby mediating between the unreliable IP network and the synchronization-sensitive GSM interfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The synchronizers perform preliminary buffering and rate adjustment of incoming IP packets before forwarding them to the GSM interfaces. By pre-processing packets to ensure proper timing and synchronization before they reach the GSM layer, the system prevents synchronization issues from propagating through the network stack.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If data is transmitted over discontinuous IP networks without synchronization management, then network flexibility is improved, but session continuity deteriorates due to packet discontinuities causing session resets

Engineering Contradiction:

Improvenetwork flexibilityVSAvoidsession continuity

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The synchronizer acts as a mediator that absorbs the discontinuities from the IP network and presents a continuous, synchronized stream to the GSM session. This intermediary layer protects the session from IP network variations while maintaining network flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The synchronizer implements buffering mechanisms that cushion against packet arrival variations and discontinuities before they can disrupt the session. By pre-buffering packets and smoothing out timing variations, the system prevents session resets while maintaining flexibility in the underlying network transport.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If synchronizers are added to maintain packet synchronization over IP networks, then synchronization reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The synchronization function is segmented into separate, dedicated synchronizer components (212, 214) that can be independently deployed in BTS and AGW devices. This segmentation allows the complexity to be isolated to specific modules rather than distributed throughout the entire system, making the complexity more manageable and maintainable.

Inventive Principle:

Principle #1Segmentation

4Stability of the object's composition

If replacement data is generated to repair packet discontinuities, then session stability is improved, but data loss increases due to generation of synthetic replacement packets

Engineering Contradiction:

Improvesession stabilityVSAvoiddata loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of information

Solution Approach 1:

The system generates replacement packets as temporary, disposable artifacts that serve only to maintain session continuity. These replacement packets are inexpensive to generate and are designed to be short-lived, serving only until the next valid packet arrives or the session is naturally terminated. The loss of information is acceptable because these are control/management packets where exact data fidelity is less critical than maintaining session state.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP2174516B1Transporting GSM packets over a discontinuous IP based network

Publication Date: 2015.12.09 BROADCOM INC

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AI summary

A system for transferring data includes an interface configured to receive data that is sent via a first link, and a processor coupled to the interface. The processor is configured to: receive data that is sent via a first link; determine whether there is discontinuity in the received data, the determination being based at least in part on information included in the received data; in the event that the received data includes a discontinuity, generate replacement data that repairs the discontinuity; and transmit at least a portion of replacement data to a second link such that a synchronization requirement associated with the second link is fulfilled.