Mobile operator drastically reduces testing hardware needs and related investment while significantly improving efficiency
Optimising the deployment of new GSM/GPRS services
1. Background
A mobile operator wanted to accelerate the deployment of new GPRS/GSM services while minimising the impact on the operational network as well as keeping the costs to a minimum.
 In order to test in the test-bed a new service, the mobile operator needs to analyse signalling information (initially two Gr Interfaces) between the central HLR database which identifies users with respective rights, and the SGSN, as well as other interfaces, including in this case two times the A, Abis and Gb interfaces. The operator's system set-up consists of Nokia base stations (BTS), Siemens Mobile Switching Centres (MSC) and Tektronix analysers
In the pilot phase prior to the introduction of the new service, the above-mentioned interfaces need to be made accessible to the engineers of the test-bed, located remotely, but in the same city. In this testing phase four analysers are needed, simultaneously analysing the interfaces to shorten testing.
In the operational phase the Gr interfaces need to be analysed for troubleshooting by the operational maintenance centres, located in two remote cities.
This results in the set-up below for the initial testing phase, before optimisation:
Diagram 1: Design before optimisation
2. System Requirements
In order to be able to make optimal use of its infrastructure, test equipment and engineering staff, the mobile operator put forward the following system requirements and constraints:
1. The Gr signalling information located in two E1 lines between the SGSN and the HLR needed to be analysed simultaneously both locally and remotely by several analysers, without disturbing the operational lines.
2. As the other E1 interfaces were already in use for other purposes, and taking into account the cost of additional E1 interfaces on the Tektronix analysers, only one E1 interface on the analysers could be used to monitor both the Tx and Rx signals of both E1 lines.
3. To further reduce recurring costs, the number of E1 leased lines between the operational site, the test lab, and the maintenance centre needed to be reduced.
4. System flexibility had to be built in, in order to be able to add additional future monitoring sites, interfaces, and analysers for troubleshooting in the operational phase.
3. The Solution
a. Testing phase I Arcadiz Telecom
designed a cost-effective solution that answered all the above needs of the mobile operator. The solution for the testing phase consisted of two small TDM DaCCs systems with the requested broadcast capabilities, as shown in diagram 2. This allowed the mobile operator to reduce the number of E1 test ports on the Tektronix analysers from ten to five, and the number of leased lines from four to one. Furthermore it removed all impedance and noise disturbance from the operational lines, reducing the impact of the analysers on the operational network to a minimum.
Diagram 2: Gr interface concentrated and broadcasted
b. Testing phase II
After the above network was set up for analysing the GSM/GPRS signalling, additional interfaces needed to be analysed in the test lab, including two Gb, A and Abis interfaces. The installed solution allowed for a smooth connection of these extra interfaces to the four analysers via the DaCCs in the test lab, using the embedded broadcast and concentrating function. In this way, the mobile operator was not forced to upgrade the analysers with six additional E1 interfaces.
This resulted in the set-up of diagram 3.
Diagram 3: Addition of Gb, A and Abis interfaces to analyse
c. The operational phase
In the operational phase two remote maintenance centres located in two different cities need to analyse the various interfaces for troubleshooting purposes. The same cross connect of the operational site is used to concentrate the same Gr interfaces to two extra E1 long haul leased lines. By doing so, there was no need to add six additional long haul E1 leased lines, and two E1 ports on the analysers in the maintenance centres. This results in the setup of diagram 4.
Diagram 4: Addition of analysers in remote troubleshooting centres
4. Cost savings and advantages
The use of the DNX allowed the mobile operator to reduce significantly both investment and recurring costs, as shown in diagram 5. With the same token, the operational network became more reliable as physical tapping of the E1 cables for analysis purposes was avoided.
a. Investment cost
Taking into account that the cost of the analyser is 300k with additional 10k per E1 interface, the cost savings amount to 50k for the first testing phase, 60k additional for the second testing phase, and 20k additional for the operational phase.
b. Cost of leased lines
Taking into account that the monthly cost of the local leased lines is 600, and for the intercity leased lines 1500, the yearly cost savings amount to 21k for the testing phase with an additional 108k per year for the operational phase.
c. Maintenance
Avoiding the tapping of the E1 copper wires makes the network more reliable as the analysers will not interfere with the network. Although the cost savings inherent to an increased up-time of the network are not included in the chart below (metrics unavailable), they are estimated to be the single largest cost saving.
Diagram 5: Accumulated Costs and Cost Savings for the first year
5. Competitive Position
The DNX family of systems provides a right-sized, flexible and feature-rich solution. No serious alternatives providing the same scalability, grooming, cross connect and broadcasting functions have been identified on the market today.
The DNX system allows for tapping nx64kbps circuits inside E1, E3 and STM-1 interfaces. It starts from 8 E1s and can grow to 512 protected non-blocking E1s, and 8 STM-1, with unlimited broadcast capability, maximising the protection of the initial investment for future addition of sites and analysers.
About Arcadiz Telecom
Through the years Arcadiz Telecom has become the partner of choice for many of Europe's leading carriers and service providers. Our approach? A thorough analysis of our customer's current - and future - needs in order to provide them with the best possible, innovative, reliable and cost-effective solutions.
Cost-efficient and innovative
In today's challenging environment our customers need to constantly expand and improve their services offering, while at the same time boosting profitability by reducing operating expenses and making even better use of existing infrastructure. Arcadiz Telecom is totally dedicated to meet these needs and builds upon years of industry experience. This is why Arcadiz Telecom has chosen to team up with best-of-class suppliers offering leading edge technologies and systems. These relationships and our in-depth knowledge and understanding of the industry and the carrier and ISP marketplace allow us to design, implement and support tailor-made solutions.
Contact Information
For more information on this case, contact Marc Vandeputte, Business Development Manager at Arcadiz Telecom.
Email: marc.vandeputte@arcadiz.com
Telephone: +32 16 392 690
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