AMG4.6 and LSF2.1

Status date

There are two separate development efforts for this project which are captured internally within Altobridge as AMG4.6 and LSF2.1.

AMG4.6 Project
AMG4.6: The main objectives of AMG4.6 were to satisfy requirements from our existing customer base to increase the value proposition of the AMG system. A number of features were added to this release including Edge, AMR, Channel Quenching and enhancements to the current operation of the Bandwidth Manager functionality. This release allows for a smarter internal method of managing the ever increasing number of terminals which our customer base chooses to deploy within their network.

LSF2.1 Project
LSF 2.1 builds on our initial release of the Local Switching product by improving its functionality. Specifically in the areas of supporting Multiple PDCH channels for GPRS and Edge, Licensing, codec matching and the integration of the LS OMC with a Vendor Network Management System. In addition to the software development there is a comprehensive set of customer facing documents and training materials.


The new suite of customer bandwidth terminals will need to be closely managed as each one is quite unique. This will be handled through regular communication with the customer from a project management perspective but also through rigorous onsite testing with the customer.

For LSF2.1 end to end System Test was only possible in the customer lab environment. As such we introduced in a Joint System Test phase.

The Multiple PDCH Feature required significant amounts of lab testing and recoding due to the complexity of the feature. This functionality was being implemented for the first time on the vendor hardware.

The implementation of the NetAct (OMC to NMS Integration) feature while not a difficult feature required a long delivery cycle. This was primarily driven by the requirement to integrate with a 3rd party Network Management System.


We have clearly demonstrated our ability to provide both single and multiple TRX remote system which generates a positive Return On Investment for GSM operators and helps them meet their universal Service Obligations for small communities (100 to 200 users) with a relatively high ARPU of 10$ to $20. With the release of AMG4.6, Altobridge will further enhance its product offering by enabling customers to use a wide variety of bandwidth terminals thereby allowing them to extend their market penetration as the end customer needs dictate. Altobridge will further refine and improve the existing backhaul bandwidth savings to be made through the implementation of the Channel Quenching feature.

This project has the following benefits:

  • Cellular operators using satellite Abis or terrestrial Abis can achieve significant savings. Consider a scenario where an operator wants to deploy additional coverage in a remote community where typical backhaul is limited or difficult to install. The only option may be to use expensive satellite links. LS minimizes the amount of traffic over the backhaul, which allows the operator to deploy coverage costs effectively. Using LS the costs related to leasing Satellite bandwidth can be reduced by up to 70%.
  • First mover advantage – this is where an operator is the first to deploy GSM coverage together with LS in a rural area where majority of traffic is voice. LS allows the operator to secure maximum savings as all local calls are on the same network.
  • Existing sites can be easily migrated to LS with reduced backhaul costs.
  • Sites can be extended without the need to increase backhaul capacity.
  • The existing network architecture and business model remains unaffected by implementing LS.
  • The core network remains in control of the call and in control of all charging.
  • Existing features and services of the existing core network are seamlessly preserved for subscribers.
  • No modification is necessary to the existing BTS and BSC.
  • There are reduced backhaul requirements for large “Special Events” or “Exhibition” sites.
  • Potential increase in voice traffic as the voice quality is considerably better for local calls than backhauled calls. Typically customers stay on calls longer when call quality is good.

The LS solution offers a significant reduction in operating expenditure of GSM sites as a percentage of calls are locally switched, reducing satellite and terrestrial bandwidth requirement. This results in extra savings for the operator. Satellite bandwidth requirements are further reduced by optimisation of the Abis over IP.

The following codecs are supported:

  • Full Rate (FR)
  • Half Rate (HR)
  • Enhanced Full Rate (EFR)
  • All AMR codecs

LS supports intra cell handover and Inter cell handover within the RGW. This means that the call remains locally switched after the handover. If one of the parties on a locally switched call requires handover to a cell outside of the RGW, the call is handed back to the network.


AMG4.6 Project

Architectural Diagram

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BTS: This element of the overall system shall consist of a standard low power pico-cell BTS (IP Access BTS, note that AMG5.0 will add support for the Ericsson PICO BTS).

Remote Gateway: The Altobridge Remote Gateway, in conjunction with the Altobridge Ground Gateway, shall enable the use of minimal bandwidth while providing ubiquitous GSM Voice and SMS services to mobile users. It essentially shall emulate the GSM function of a BSC in conjunction with the Altobridge Ground Gateway.

Remote Gateway Structure

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Satcom Terminal: This aspect of the overall solution provides connectivity between the Remote Gateway and the Ground Gateway.

Ground Earth Station (GES): This entity of the overall solution provides the connectivity between the satellite network and terrestrial telephony and packet data networks. It is the complimentary peer of the satellite terminal equipment.

Ground Gateway: The Ground Gateway shall provide the complementary peer of the Remote Gateway and this system shall provide a standard inter-connect to the Public Land Mobile Network (PLMN) this essential part of the Altobridge product offering shall enable multiple Remote Gateways to interact with standard GSM network through one interface.

MSC: The Mobile Services Switching Centre (MSC) is an integral part of an existing PLMN. It shall provide standard MSC and Visitor Location Register (VLR) functions for the subscribers at remote locations.

LSF2.1 Project

Architectural Diagram

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To integrate Local Switching into the customer product suite, two new network elements are integrated into the current BSS architecture:

  • RGW - remote Abis gateway located with the BTS,
  • CGW - central Abis gateway located with the BSC.

The RGW (Remote Gateway) and the CGW (Central Gateway) as seen in the figure above are the base components of Local Switching technology. The RGW is the interface between the remote BTS and the E1 or T1. The CGW is the interface between the BSC and the E1 or T1.

The other components (BSC, MSC etc) are independent of the Altobridge solution and not governed by our architecture in anyway. As such, their function remains the same as described previously in the AMG architectural description.


As this project encompasses two separate deliverables, there were two project plans as detailed below.

The implementation and execution of both projects was achieved and all deliverables have been completed.

The project plan addressed delivering the software features on the AMG4.6 release in line with the planned timeline to exceed customer expectations.

Specifically, the features developed and delivered include:

  • AMR
  • Edge
  • Enhanced Bandwidth Management
  • Extended Welcome Character Set
  • Channel Quenching
  • Optimised Long Signalling
  • Full Rate Calls
  • EP8 Features for Aero Market

This project delivered the following features;

  • Licensing
  • Codec Matching
  • Multiple PDCH Support for GPRS & EDGE
  • OMC to NMS Integration
  • Customer Document Set
  • Customer Training Materials
Current status

Specific details follow:-

AMG4.6 software has been developed and delivered.

LSF2.1 software has been developed and delivered.