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The Shrinking Mobile Network

Wed, 10/10/2007 - 11:38am
Compact and fully-integrated, a NIB helps companies quickly build an internal mobile network that allows real-world testing.

By Gilad Peleg, LGC Wireless

Successful mobile networking products depend on thorough testing in real-world environments. What works for one handset, application, or service platform may not work for another, so the testing environment should be flexible enough to support all possible scenarios. Traditionally, such testing has required simulating network responses (which don’t guarantee real-world interoperability) or deploying an expensive on-site network whose cost and complexity drive up the cost of development and lengthen time to market.

As the pace of mobile product development quickens, developers need to find better environments for testing interoperability between end user devices, access and

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Figure 1: Mobile network elements.
core network products. Whether the product is a piece of carrier networking gear, an enterprise convergence solution, a management or provisioning system, an in-building wireless system, feature software, or a handset, developers must be able to use a test network that presents a broad range of scenarios to meet international market and application requirements.

Traditional Test Alternatives
Mobile product development is never static. Mobile chipsets are now being built into laptop computers and other products. Fixed-mobile convergence (FMC) and high-speed data protocols such as HSDPA are further changing the landscape for mobile developers, impacting the feature sets and performance of everything from BSC and BTS equipment to over-the-air administration, management systems, PBX interfaces, Wi-Fi convergence platforms, and handsets. However, there is also no shortage of competition, so every developer tries to pack as many differentiated features as possible into its products.

Testing options have never kept pace with the development of new mobile services, platforms and devices. Today, engineers spend 20% to 30% of the development cycle in testing and verifying a product. By reducing the time spent on this part of the process, companies can speed the product cycle, reduce time to revenue, and become more competitive.

Until now, developers had only two options for testing new devices: build a test network or simulate network activity. Each of these options has drawbacks. Building a network is a complex business. The company must acquire an MSC, a BSC, a BTS, home and visitor location registers (HLR/VLR), interfaces to the PSTN and PBX equipment, and application servers (see Figure 1).

Typically, this equipment is designed to support millions of subscribers, so the company must pay high-capacity prices for this equipment even though it will only have a handful of active devices on the network at any given time.

In addition, traditional cellular network equipment is difficult to deploy and configure. Most systems are quite large and require forklifts or cranes to put in place, and the various components must be integrated and configured on-site. Moreover, most network systems are quite large, and were never designed to be used within the space and power constraints of a development lab. These factors combine to ensure that only the largest companies have the resources to build an in-house network.

When building a test network is not an option, the only option is to simulate a network environment by buying or building simulation equipment. In fact, developers can often spend 10% to 15% of

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Figure 2: Configuration for handset testing with a NIB.
the total development time creating simulators to test their products. These simulations can check the accuracy of protocol implementations, but they can’t provide real-world interoperability testing on a live network. As a result, a product can "test" fine in the lab, but then have significant problems when put into live operation on certain networks.

A Better Solution
If the ideal scenario is to test on a live network, the solution is to have an easily deployable, compact, and low-cost network. Today, it is possible to obtain such network-in-a-box (NIB) products, which are ideal for testing new devices. Initially developed to support small numbers of subscribers in remote areas, these mini-networks incorporate a BTS, BSC, MSC, (HLR/VLR), PSTN and PBX interfaces, and application servers to deliver a fully-functional GSM network. As such, a NIB supports true functional and load testing for GSM networks. Compact, complete, and fully-integrated, a NIB allows companies of all sizes to quickly build an internal mobile network that allows real-world testing.

NIBs offer numerous features that address the challenges of other testing alternatives:
•Compact size and low weight — A NIB can be lifted by two people and installed in a standard 19 inches rack or on a tabletop.
• Cost effectiveness — A NIB is priced low enough that smaller facilities can afford one.
•Low power consumption — A NIB’s power budget is well within reach for even smaller development labs.
•Simple deployment — A NIB can be deployed within two or three hours by lab personnel, so companies don’t have to schedule a visit from the network equipment vendor’s onsite support team.
•Full testing functionality — A NIB supports all standard testing parameters and statistics for easy analysis and troubleshooting.
•Easy configuration — A NIB offers full configuration of all GSM system level parameters on both BSS and NSS ends, making it easy to perform multiple iterations of tests or multiple test cycles. In addition, its high integration minimizes manual cable changes.
•Service level reports — A NIB generates service level reports to reflect Erlang traffic/BHCA traffic trends, call success rates, SMS success rates, and trunk statistics. BSS measurement reports are available on a per-cell and BSC-level covering GPRS data statistics, and these can be post processed using external tools.
•Log analysis — A NIB usually features a low-level log collection capability similar to the one in a protocol analyzer. The log can be inspected to analyze one particular call based on the IMSI.
•Multi-band service — A NIB supports 850, 900, 1800 and 1900 MHz GSM frequency bands so devices can be tested for any service, carrier, and market.
•Local switching — A NIB offers local switching to eliminate the need for traffic to move out to a macro network for switching.
Rather, it allows devices in the lab to communicate solely within the testing environment without the need for additional switching hardware.
•Basic services — A NIB supports call forwarding, call waiting, call hold, call transfer, handover, roaming, connectivity to other networks, and GPRS.
•Value added services — A NIB often supports value-added services such as prepaid calling, SMSC, AuC, EIR, video, and text-to-voice, as well as optional voice mail services.
•Modular design — While compact, a NIB has a modular design that allows the addition of new services, in order to protect the investment while allowing testing of new innovations over time. Expansion options via hardware and software include higher capacity, support for both circuit-switched and packet data, and value-added services such as voice mail and prepaid calling.

Deployment Scenarios
As a complete network solution, a NIB offers significant flexibility in testing for a variety of applications and services. The following test scenarios show some examples.

Testing Client Applications
A GPRS-enabled NIB provides a complete, one-box solution for testing cellular phone clients (Figure 2). On one side of the network, the NIB provides the network. On the other side of the network, the developer provides the

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Figure 3: Configuration for GSM and Wi-Fi integration testing with a NIB.
smart phone and application server for testing e-mail, ring tone downloads, web browsing, mobile video, location-based advertising, text messages, push-to-talk, and other services. The NIB’s integrated MSC reduces the cost and complexity of the deployment, and allows testing without connections to a live network.

Testing GSM and Wi-Fi Convergence
The NIB’s integrated HLR/VLR/AUC/EIR functionality provides an environment suitable for GSM/Wi-Fi convergence platform tests (Figure 2). For example, the SIM card in a dual-mode phone would be used for both voice and data billing and the carrier could provide unified billing for both hotspot and cellular network usage. Developers of convergence gateways would use the NIB to test handover from the GSM to the Wi-Fi network through their gateway.

As a complete solution, the NIB enables rapid configuration of multiple test suites in scenarios like those mentioned above. Engineers can create and manage test configurations remotely using a graphical interface, and then can run, diagnose, and analyze different tests without having to reconnect cabling between multiple devices. The NIB also provides traditional logging to facilitate analysis and debugging.

One additional advantage of a semi-portable device such as a NIB is that developers can use it for early marketing efforts while the product is still in alpha state. Since the NIB can be moved easily, it can be used for on-site customer demonstrations of emerging products. In this case, customers will see the product working with an actual GSM phone on a true GSM network.

With NIB systems now available, developers have an opportunity to significantly reduce the cost and time requirements for real-world testing. Wireless technology is expanding more rapidly than ever, and mobile device and infrastructure developers must keep pace or risk losing market share. NIB solutions reduce testing complexity by allowing developers to rapidly build complete, real-world networks. With a NIB, developers can be assured that their solutions will work in the real world, accelerating time to market with fully-tested products and eliminate nasty surprises once new products hit the market.

About the Author
Gilad Peleg is vice president of marketing at LGC Wireless – Network Systems, 2495 Leghorn St. Mountain View, CA; 408-952-2400; www.lgcwireless.com.


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