Containing Network Costs

Investors who have funded wireless projects do not like surprises. This means PCS start-ups need to spend time with extensive planning. When you are configuring network arrangements, it is important that you minimize recurring monthly costs and optimize containment strategies.

To contain costs for the enterprise, network architects should take every precaution to control equipment and infrastructure costs. A traditional configuration for a start-up provider's basic enterprise structure features the project manager that is focused on minimizing start-up time. This operator's basic configuration has a fully redundant switch architecture, over-the-air service provisioning platforms and independent service platforms (voice mail and short message service) as well as administrative network-management systems. Because this operator will use SS7 technology to support roaming, each switch and service platform must have access to the public signal transfer point (STP). For example, SS7 supports access to a caller's HLR database for roaming. In this situation, the roaming call will be held in the visitor location register temporarily until it can be validated against an HLR database. These SS7 links also support access to the RBOC's associated STPs to establish routing parameters and access to other custom services, such as fraud control or protocol conversion. For example, to support LNP, a special query(s) has to be sent to a supporting STP to identify the routing for the LNP directory number.

Although this network is simple to configure initially, it is cumbersome to build a meshed network as you add more devices. This network configuration arrangement is manageable, but it can become costly as the physical configuration and the need for SS7 links expand.

As the operator expands, adding facilities will require new SS7 links. Eventually, as more devices are added, all of the devices must be interconnected. You can avoid the problems of managing a complex mesh network by adopting a hub strategy from the beginning. This strategy can save money down the road as you add more subscribers to the network.

RETHINKING YOUR NETWORK Carriers first established STP computer systems to support call traffic routing within the public network. Initially, companies such as AT&T, NEC and Nortel developed these expensive dedicated computer facilities using proprietary software to support a singular function of resolution for call routing. But with additional functions such as fraud control, protocol conversion between networks, advanced intelligent network (AIN) services and now LNP, new software had to be developed to enhance STP operation.

Wireless providers have found that access to these services along with SS7 access increases operating costs. So, why not import this function into your own enterprise?

This is the strategy that Central Wireless Partnership (CWP) decided to take. The carrier established its own dual STP. An internal STP strategy allowed CWP to consolidate its SS7 link interfaces from 12 to four links. Although most service providers first focus on radio and switch infrastructure to generate revenue, CWP planners started out by internalizing STP requirements. Harry Midgley, CWP director for engineering, said this strategy will allow more options down the road. Initially, this solution consolidated CWP's costs for maintaining multiple SS7 links between its service platforms and the public network. For example, provisioning SS7 links under a plan would have cost approximately $42,000 per month ($3,500x12).

By adopting the hubbing strategy, CWP's network planners were able to start out with a more modest SS7 link configuration ($14,000 per month). This cost difference allowed planners to reduce start-up costs by more than $330,000 in annual SS7 link charges.

Because an internal STP houses all of the signaling for the network in one system, it also incorporates most of the software required to report traffic on an internal basis. This allowed network planners to establish a single point for network traffic metering and measurement, which eliminated the need to monitor and gather data from individual devices on the network. This, in turn, reduced personnel costs for each facility, Midgley added.

HIDDEN SAVINGS The design of both public and private networks is a well-developed discipline in which network architects are always seeking more cost-effective solutions. Considering the potential savings, it is not surprising that CWP decided to establish its own internal STP function as part of the enterprise network.

The CWP network used a versatile signal point (VSP) platform to establish the functions of a STP within its network. The scaleable system allowed CWP to start with a modest investment. In anticipation of LNP requirements, CWP also realized that the internal STP function would assure a more efficient routing process because lookup queries can be accomplished within the same enterprise.

Eventually, the internal STP will allow CWP to install its own LNP application using the VSP platform to support the function. This will allow internal LNP queries, which will improve network throughput while eliminating any RBOC charges for SS7 LNP queries. For example, assuming 1, 000 LNP queries per hour, internal LNP queries could save about $400 for every 8-hour operating period. This means internal LNP queries could save more than $400,000 a year. In addition, an internal STP can absorb other special service charges, which saves additional operating costs.

Midgley added that because the MicroLegend VSP platform is an open platform, it can operate several scaleable applications. In the future, he added, CWP network planners will implement other AIN applications, which can be supported by expanding the VSP platform. Adopting an internal STP strategy will allow CWP the flexibility to scale up and support new requirements quickly.

CWP will be able to meet expansion requirements through attached platforms using a TCP/IP socket interface. STP technology has reached a high level of maturity since broad deployment by major wireline carriers. But until now, only large-scale STP systems in the million-dollar range were available because major carriers needed to support many more SS7 network links. It only was recently that vendors began offering small scaleable systems to support networks with minimal requirements. Systems such as the VSP platform are an ideal internal STP vehicle because you can expand them easily to meet future network requirements as they develop.

To meet the needs of a competitive market, wireless carriers will have to closely evaluate network flexibility to support new applications and services. For example, some operating environments have nodes with limited SS7 support. An internal STP architecture that provides a bridge between SS7 networks and external applications will enable you to sidestep the costs for otherwise highly complex service control points. Do not overlook the advantages of an architecture that supports rapid deployment of new services. You must be certain that your equipment investment has an upward migration path in place. This will allow you to meet subscriber demands in a timely and cost-effective manner.

A CDMA minicell serves as the radio link from the cell site. This system is linked to the digital switch, which is part of the MSC and supports the switching fabric for the wireless network. Another component is the executive cellular processor, which supports call processing, system intelligence handling, system configuration and feature control. The operations maintenance processor supports the operations and maintenance tools required to maintain the mobile system.

A PBX supports the Central Wireless Partnership (CWP) internal voice communications requirements, including the customer-support center. Customer-support agents work with over-the-air-function processors, which enable CWP agents to support over-the-air provisioning for new subscribers who dial directly into the center. This system allows the customer agent to capture the serial number of the calling subscriber's handset and create a new subscriber data record. It also allows an agent to update or change the calling features of existing subscribers who call in for changes or updates to their service. CWP uses voice-messaging service platforms to provide voice messaging, direct dial, pager notification and automatic call-back services for subscribers and uses short message servers to send messages to subscribers.

The service platforms described above all are linked to the SS7 routing support on the public network through VSP platforms, which serve as internal STPs.

An integrated switch-management system supports administrative aspects of the CWP enterprise. This supports real-time data collection, LD billing, inventory, accounts receivables, rate estimator and point-of-sale capabilities.