By Yang Ji

Base stations are the key energy consumers on any mobile network; their monitoring and upgrade are essential if operators are to compete. Statistics from within the industry indicate that 65 percent of communications interruptions are caused by power supply failures, with 85 percent of them discovered after more than 12 hours, thanks largely to customer complaints. Other challenges to base station operation include heat, fire, flood, and theft. All of these make onsite power & environmental monitoring essential.

Numerous operators are adopting solutions that manage site power consumption and its environmental impact. Such solutions must unify power & environmental monitoring, ensure power supply/security, reduce site visits, and cut OPEX. With efficient monitoring and optimization, operators can enhance their power consumption efficiency.

Efficient in-band networking

Theft is a daunting problem for remote sites, with batteries and solar panels being the prime targets. Greenfield operators generally have limited resources for remote monitoring and therefore need a cost-effective solution to guard against theft.

Traditional network monitoring modalities include E1/partial E1, GPRS/CDMA1X, SMS, VPN, and PPP/xDSL; all require additional networking equipment, plus deployment or renting of transmission resources. Moreover, network commissioning during site migration wastes time and energy.

Huawei provides an alternative site solution which uses an RS485 serial line to connect monitoring control units (MCUs) with base stations. Through a specific channel for site operation and maintenance (O&M), operators can enjoy in-band networking from the MCU to the network operation center.

If deployed for a typical 2G site, the MCU connects the O&M channel for the base transceiver station (BTS) through an RS485 serial port. The BTS then collects and identifies data, and sends it to the base station controller (BSC). After collecting the data, the BSC sends it to the element management system (EMS). The EMS does not depend on the BTS-BSC transmission mode; while ATM, TDM, and IP all support in-band transmission. As a result, the MCU can communicate transparently with the EMS through the existing BTS-BSC channel.

With in-band transmission, operators need not invest in transmission hardware or rent/build transmission resources, which significantly reduces the costs involved with building the power and environmental monitoring systems.

Maintenance efficiency is also enhanced as the system requires no additional testing, thanks to the direct MCU-BTS connection. Traditional monitoring may require close coordination with transmission systems. If the transmission systems are adjusted or disconnected, the monitoring systems are affected; site visits are then required to update the configuration. In-band transmission effectively avoids this issue.

With Huawei solutions, operators can build their power and environment monitoring systems effectively, at reduced cost, while enhancing site management and lowering the impact caused by possible theft.

Integrated management

Onsite energy conservation requires coordination between the network and power equipment, as well as flexible power usage based on network load and environmental factors. Some operators are starting to reduce the number of active carriers so that they are more in line with load levels. By referring to past and present traffic data, operators can predict future traffic levels and adjust the number of active carriers accordingly.

Traditionally, power supply modules and network equipment are managed separately. Through EMS, operators can turn off a carrier but not a power module. Integration of the EMS and the power & environmental monitoring system can help solve this problem and enhance maintenance efficiency. The monitoring system provides an interface to the EMS, through which the EMS collects data; the EMS can then manage alarms and issue work commands in a centralized manner. In this context, operators can make better decisions by understanding both service loads and energy efficiency. The monitoring system and EMS can be deployed on the same server, reducing the investment needed for servers and databases.

OPEX can be significantly reduced through integration of the EMS and power & environmental monitoring system. Through flexible carrier activation, power consumption onsite can be reduced by eight percent. Through unified alarm control, operators can more quickly determine whether or not an alarm is generated from the network or the power supply equipment, which will reduce the number of site visits.

Centralized vs. multi-layer monitoring

Power supply maintenance, refueling, temperature control failures, and equipment theft are the primary triggers for an onsite visit. For urban radio sites, some operators use a multi-layer control system for their power & environmental management. Each city has a power & environmental monitoring system which reports to a higher-level monitoring center. This architecture has brought a number of challenges, including complexity, difficulty in deployment, poor data consistency, and separate northbound connections.

Huawei has rolled out a centralized monitoring solution that should help resolve these difficulties. Through in-band transmission and integrated management, the solution enables each MCU to communicate with the monitoring center, while its simplified structure eases the burdens of deployment and maintenance. Centralized monitoring can also facilitate unified service, while ensuring data consistency and integrity. However, centralized monitoring makes service management and hardware all the more important. The ripples from network or server failures will travel farther than before, so greater software reliability is a must.

Centralized monitoring and multi-layer monitoring have their own strengths and weaknesses. High-performance servers have emerged recently which facilitate centralized monitoring and reduce CAPEX. In comparison, multi-layer monitoring requires complex networking, which is a key weakness. Therefore, centralized monitoring is becoming mainstream; operators should consider the differences between the two and plan their networks accordingly.