Wireless Management
Issues Facing Cellular Carriers Today
RESPONSE TIME & DISTANCE
Currently, cellular providers deploy Mobile Switching Centers (MSC) to support packetized cellular voice and data traffic, which is transported into the MSC from cell sites containing Base Transceiver Stations (BTS). The BTS, or cell sites, are spread out across a given geographic footprint.
These cell sites can be very close together in high-density urban areas such as New York, Los Angeles, or Chicago. It is more typical to see an MSC deployed at the center of a major urban area that has a large suburban area with even larger rural districts surrounding the city. Cities such as Orlando, Memphis, and Denver reflect this type of cell site deployment. There are also some areas, such as Montana and Wyoming, which have very large rural areas. In these states, a cell site could be located very far from the MSC.
TRANSPORT MANAGEMENT
A major source of outages comes from T1 and transport related issues. When a transport issue occurs, the MSC receives an alarm from the affected BTS. The transport provider is called and a trouble ticket is issued. The transport provider runs his diagnostic tests, usually a loop to the network interface unit (NIU) at the site. If the NIU loops, he closes the ticket with a "no trouble found" action code.
The burden is now on the cellular carrier to dispatch a technician to the site to determine the root cause of the problem. Once at the site, the technician can plug into the BTS and analyze the diagnostic information. He can put the transport interface into loopback and call the carrier to determine if the loopback is visible at the Central Office. If it isn't, the transport provider is then willing to dispatch a technician to repair the problem.
RET CONTROLLERS
Some carriers have deployed antennae which have the capability to be aimed via Remote Control Units (RCU). The SC-8100 contains an optional AISG v2 compliant RET controller, allowing antenna tilts to be performed and monitored remotely from anywhere on the network. Again, this saves the cellular operator from dispatching a tech to the site to aim the antennae. For cell sites with a RET controller already installed, PUMA can provide the same level of access to the RET controller as it does for all other network elements at the cell site, allowing remote antenna aiming without the need to travel to the cell site.
POWER AMPLIFIERS
Multi-Channel Power Amplifiers (MCPA) controls the signal strength to the antenna. If there is a question about the status of an MCPA, a technician is dispatched to plug into the unit and obtain the current values. With PUMA, these values can be read and changed by a technician from anywhere on the network.
The Solution to the Problem
TelStrat's PUMA (Platform for Unified Management Access) offers a solution to these problems. By deploying PUMA at the cell site, technicians can access critical components to evaluate the exact cause of an outage or alarm without driving to the site. The PUMA product provides remote access to both traditional serial and Ethernet TCP/IP based network elements as well as contact closures, voltage and current generating network elements. Armed with a connection into the cell site, the cell technician can place the affected transport interface into loopback without traveling to the site. The transport provider can then determine whether or not he can see the loopback. If not, the transport provider will dispatch his technician to repair the problem. The cellular carrier has now saved twice: once in saving the cost of sending a cell tech to the site for diagnostic purposes, and again by reducing the amount of time it takes to get the BTS back up and fully operational.
PUMA allows cellular network operators to quickly analyze the problem area, identify the component at fault, determine whether the problem is with its equipment or with the local IOC, and dramatically reduce the cost associated with an outage while reducing mean time to repair (MTTR). In fact, PUMA has been proven to substantially reduce the number of trips required to correct a failure and can often be shown to pay for itself in less than one year.
The PUMA platform allows up to 512 simultaneous users to perform Operations, Administration, Maintenance, and Provisioning (OAM&P) of remote network elements all by accessing a single IP address.
The TelStrat PUMA system consists of two elements:
- One or more Central Controllers (CC-9000)
- A Site Controller (SC-8100) at each cell site.
The CC-9000 serves as PUMA's central command center, communicating directly with each SC-8100 Site Controller, and focusing the power of remote SC-8100 units into a single, unified point of network status information and network ele¬ment management. Multiple CC-9000's can be located in regional centers or management offices, as well as at NOC centers.
The SC-8100's are located at each cell site. The SC-8100 provides physical connections to all remote network elements, whether by serial or IP (Ethernet) connections, normally open or normally closed alarm monitoring inputs, form C relay outputs, or analog inputs (0-10V or 4-20 ma). (See Network Diagram below.) Each SC-8100 can support up to 128 individual network elements, and each CC-9000 can support up to 4,096 SC-8100's, and up to 500 simultaneous users.
The PUMA platform provides a cellular carrier with two substantial benefits: a substantial reduction in the number of truck rolls needed to operate a given cellular network and a reduction in the length of an outage when one occurs. Any operator that is under pressure to reduce costs and improve network availability will find the PUMA platform to be a welcome addition to his OAM&P capabilities.
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