|Issue:||North America 2011|
|Topic:||Energy and infrastructure for LTE deployment|
|Title:||Director, Product Management, Energy Systems|
|Organisation:||Emerson Network Power|
Paul Misar is Director, Product Management, Energy Systems for Emerson Network Power. Mr Miser has more than 15 years of experience in the telecom outside plant industry, both in the wireless and wireline arena, focused on product management, design and implementation. Paul Miser holds a BSME from the University of Illinois, Chicago.
As LTE evolves, service providers will move toward data-only networks, carrying voice in standard VoIP format. To reduce infrastructure costs, operators will shift network topology and the system requirements at each cell site. This will drastically reduce power requirements and make alternative and renewable energy more financially attractive. LTE is also forcing a convergence of wireless, wireline and cable networks to provide backhaul. Distributed antenna systems with multiple antennas throughout the neighbourhood help achieve the speeds needed for data-intensive services.
Energy and infrastructure for LTE deployment by Paul Misar, Director, Product Management, Energy Systems, Emerson Network Power Mobile broadband has become so significant in our daily lives that we have become accustomed to immediate broadband access at home, in the office and on the road. This results in an explosion – with more to come – in the amount of data moving through the wireless infrastructure. To meet the demand for faster data connections, the industry has responded with two new wireless platforms – WiMAX and Long Term Evolution (LTE) – as next-generation wireless platform technologies. In North America, LTE is the choice of existing mobile service providers, providing many advantages over WiMAX technology. LTE has led service providers to rethink their current deployment strategies in order to provide the highest data speed throughout their networks. Therefore, one of the main strategies has been to move to a ‘nodal’ infrastructure involving a greater number of sites with lower power requirements. In many cases, a single cell site services a number of antenna sites, drastically reducing the overall infrastructure and increasing network reliability, while decreasing the power requirement at each site and of the network as a whole. LTE’s promise of lower-powered sites imposes an overall shift in the network topology and the system requirements at each cellular site. These changes drastically reduce the amount of DC power required per site, the overall cooling requirements, and the site footprint. LTE also is forcing a convergence of the wireless, wire line and cable networks. Greater data use and LTE efficiencies are pushing more data through the wired network. Within three to five years a new topology will emerge. Wireless backhaul evolution Data-centric standards such as LTE require a more robust network backhaul but using the wired network for this creates its own set of challenges. LTE’s greater data use and efficiencies mean that more data must use wired network backhaul. Data, then, as it become a major revenue stream, will force wireline carriers to reconsider three specific areas: • Cost – Dramatic increases in data traffic require additional bandwidth. Traditional copper-based T1 systems can’t handle large data flows without increasing the line count threefold at each site. The cost of leasing these lines to connect to the local wireline provider could exceed US$10,000 per month, per site. It is more efficient to move to an Ethernet-based fibre or high-speed microwave backhaul system for LTE. The wireless provider will be able to maintain the link to the wireline network, increasing reliability and reduce infrastructure costs compared to relying upon the local exchange for backhaul services. • Flexibility – Today’s backhaul solution must be flexible enough to reliably handle legacy infrastructure, second and third generation technologies, such as GSM, UMTS and CDMA and, as well, the future data backhaul needs of LTE. A backhaul solution, such as fibre-based Ethernet, is capable of providing a flexible, data intensive, network connection for both today and tomorrow’s radio technologies. • Reliability – Backhaul traditionally is the network’s weakest link. Reliability must increase as demand grows. Backhaul spending will increase as providers work to deliver the most robust backhaul systems Overall, broadband data network ownership will consolidate until just one or two dominant network management providers emerge. Front-end service providers that have few, or no, ties back into the managed data network will sell advanced mobile data products. In the near future, this will cause a major revolution in the market and affect the overall site infrastructure. LTE and the wireless infrastructure As LTE evolves, service providers will move toward data-only networks, carrying voice in the form of packetized data using a standard VoIP format. There will be great pressure to reduce infrastructure costs. Unified LTE standards will foster a more unified approach to cellular deployment with a ‘do more with less’ focus upon the costs for outside plant, DC power and site layout. Infrastructure suppliers will have to provide solutions that can do more both in smaller, more cost-effective, greenfield sites and at legacy infrastructure sites. Traditional wireless sites won’t disappear, but LTE forces providers to use innovative methods to extend the network closer to the subscriber. Mobile users are becoming more static, choosing the use of wireless devices over wired technology. ‘Smart technology’ homes will become more prevalent; they will use wireless network services to facilitate energy conservation via smart metering and to deliver full HD wireless television, phone service and high speed Internet that exceeds the fastest wireline broadband currently available. Data speed decreases as distance from the antenna grows; so to obtain the speeds needed for data-intensive services, wireless networks must move closer the consumer. One method involves deploying DAS (distributed antenna systems) networks with multiple antennas throughout the neighbourhood, providing extensive coverage fed by a main DAS ‘hotel’ located in the network. • The DAS hotel contains incoming utility power, DC rectification, radio systems, fibre splitter and management, node splitters, electronics and battery backup. DAS hotels can be housed in a walk-in enclosure or a series of small outside plant cabinets. Site style depends on availability and property cost, plus the need for growth. Low-growth potential sites are best served with several outside plant cabinets. Growth areas are best served with walk-in enclosures that can easily add radios, carriers, DC power and battery backup. • Traditional sector antennas are split up, or duplicated, among several antennas fed via fibre, generally strung along existing utility wires. • At each antenna node, power is fed by the utility company via a point of demarcation. • Site nodal electronics are powered by approximately 200 watts DC at the site and generally do not have battery backup. DAS network sites typically have three times the coverage of a traditional wireless site with the same number of carriers. Main DAS hotel sites do not require large DC power plants or large battery backups. Little or no amplification is needed to send the signal through the fibre network. Hotel sites can use less than half the current DC power and battery backup. From an infrastructure standpoint, sites require less AC power and a smaller infrastructure footprint. Although a nodal site with antennas requires DC power, AC demarcation and outside plant cabinets, these components pale in size and energy compared to an equal primary radio site. In many cases, the nodal side is connected to the utility grids with no DC back up. This may evolve based on the critical nature of the data being transferred and the types of businesses or individuals served. Existing providers will initially deploy LTE within the current infrastructure, especially if radio frequencies are available. Based on scalability and interoperability, the most cost-effective solution is to add an LTE radio system at an existing cellular site utilizing the existing radio infrastructure. This can be done by: • Deploying an LTE radio • Deploying RXIAT (Receive Antenna Interface Tray Subsystem ) equipment • Use of existing DC power and DC backup (typically oversized at existing sites) Speeds required at existing sites to maintain a ‘digital house’ will never be attained unless antennas are placed close to the subscribers. Ultimately, nodal sites may become the solution to properly distribute signal effectively through the network. The energy factor Cutting wireless network energy costs is essential for service providers. Estimates show that telecommunication networks consume nearly one per cent of global energy use. With more than four million cell sites deployed globally, the energy savings impact is significant. Cellular site optimization is vital. The focus has been on the radio system and the amount of energy consumed by the radio and overall amplification of the signal at each site. Many greenfield deployments utilize remote radio heads, or ‘Node B’ configurations, at the primary cell site. These place the amplification and antenna at the top of the tower, leaving the radio, DC power and energy backup at the base. The overall efficiency of radio distribution saves DC power, outside plant and AC distribution by as much as 50 per cent per site. In addition, the LTE technology draws less power within a smaller footprint, further contributing to the energy use at each wireless site. As power at the site continues to decrease, the advantages of alternative and hybrid energy sources become more financially attractive. A hybrid control system enables the deployment of renewable energy sources. In addition to utilizing grid power, plus a DC generator or DC batteries as standard backup, renewable sources incorporate power from solar, wind or fuel cells at each LTE site. Hybrid site architectures reduce grid energy by approximately 25 to 30 per cent per site, and provide significant energy cost reductions when multiplied by the number of sites. U.S. sites utilizing renewable energy sources can also realize a 30 per cent federal energy tax benefit. Several states offer tax incentives as well. Renewable energy also gives providers an environmental advantage that reinforces their overall sustainability message. Decreased site energy consumption allows for a broader use of renewable and hybrid energy sources. This creates the opportunity to package the systems for rapid deployment, providing overall economy of scale and flexibility. Payback, based on current electric rates, should be between three and five years. Wireless telecommunication infrastructure leaders will be those who find unique cost- and energy-efficient ways to enhance the transport network.