Green Networks: Optimizing Energy Efficiency for Green Development

ICT: The key to a green and intelligent society

Carbon neutrality attracted extensive attention in 2021 and today presents a common challenge and goal for all industries worldwide, including ICT. The ICT industry only accounts for about 2% of global carbon emissions and, in China, the three major carriers account for less than 1% of the country's total energy consumption. The ICT industry is playing a more prominent role in helping numerous industries go digital and contributing to carbon neutrality. However, the industry itself must continue to optimize the energy efficiency of telecom networks and increase the proportion of clean energy used. 

Optimizing energy consumption in the ICT industry means reducing energy consumption per bit, so that the growth in carbon emissions is slower than the growth in traffic. For example, the power consumption of each fixed network terminal has increased by nearly 20 times from the PSTN era to the gigabit era. However, network bandwidth has increased tens of thousands of times, and energy efficiency has improved by dozens or hundreds of times.

Green networks: Comprehensively optimizing energy efficiency

To help carriers efficiently cut emissions, save energy, and accelerate carbon neutrality, Huawei has introduced comprehensive solutions that integrate green sites, green networks, and green operations. The green network solution targets network architecture and optimizes networking through technical means to significantly reduce power consumption.

The green network solution features networks that are all-optical, simplified, and intelligent. "All-optical" involves two aspects: first, replacing electrical switching with optical switching; second, swapping copper for fiber on the fixed access network. "Simplified" means upgrading and simplifying networks by, for example, deploying fully converged routers, upgrading old SDH equipment with OTN, and deploying massive MIMO and fully-converged core networks. "Intelligent" means introducing intelligence to the network to reduce power consumption during off-peak hours.

1. All-optical

Optical-electrical-optical conversion and electrical signal processing are the most power-hungry processes in telecom networks. Reducing optical-electrical-optical conversions means reducing power efficiency. Replacing electrical networking with OXC-based optical networking on the transport network can slash power consumption. A core node with 96 Tbit/s capacity typically consumes about 1,000 W – less than 10,000 kWh of electricity a year – when configured with OXC. In contrast, typical power consumption with electrical forwarding configured exceeds 40,000 W, consuming more than 380,000 kWh of electricity per year, over 40 times more than the OXC solution. Adopting OXC networking across the entire network will significantly improve power efficiency. OXC is a highly integrated optical-layer grooming solution that consumes 40% less power and requires 90% less equipment room space than the traditional ROADM solution.

Swapping copper for fiber on the access network can save 19 kWh of electricity per household on the network and device sides combined, totaling 19 million kWh of electricity saved for every 1 million households each year – the equivalent of 9,000 tons of carbon emissions from thermal power generation based on the global average kWh-to-CO2 score, or the same as a carbon sink of 400,000 trees. More than 400 million broadband users are connected globally by copper and coaxial cables. Migrating these users to fiber broadband would reduce carbon emissions by at least 3.6 million tons a year. Additionally, copper production consumes far more energy and water than optical fiber production, and creates waste acid, waste alkali, heavy metal, and tailings.

2. Simplified

Technologies are rapidly evolving, and the siloed sub-networks and old equipment in carriers' networks mostly only support one function and one RAT, with high power consumption per bit. Examples include old SDH equipment that carries a large number of enterprise leased lines, single-RAT 2G/3G/4G/5G voice and data core network NEs, existing 2T RF units with relatively low transmit/receive efficiency on the RAN, and traditional single-function routers such as service routers, broadband access servers (BRASs), Internet Protocol Security (IPSec), and carrier-grade NAT (CGN). Using new technologies to upgrade old equipment can replace siloed sub-networks and simplify the network as a whole, reduce power consumption per bit, and optimize network energy efficiency.

Old SDH equipment that uses power-intensive 20-year-old technology is found in many telecom networks. The addition and deletion of services over time has resulted in many zombie timeslots in equipment. Coupled with optical distribution frames (ODFs) and air conditioning, this equipment wastes equipment room space and has poor power efficiency. Upgrading SDH equipment with the latest OTN simplifies the network, reduces power consumption per bit a hundredfold, and meets SLAs, greatly reducing equipment room space required.

With home broadband, B2B services, and content delivery networks (CDNs) moving closer to the user end, convergence network COs and even access network COs require BRAS, CGN, and IPsec capabilities. Traditionally, each of these functions requires a separate router, which increases CO power consumption. The latest router models integrate segment routing (SR), BRAS, CGN, and IPsec, all of which reduce CO power consumption.

As 4G and 5G dominate the world's telecom networks, carriers are faced with the challenge of dealing with co-existing 2G, 3G, 4G, and 5G core networks. The traditional network deployment model with single-RAT overlays will increase carriers' network deployment and O&M costs and energy consumption. Huawei's fully converged core network solution supports 2G/3G/4G/5G integration and uses technologies such as unified NFV resource pool scheduling, on-demand dynamic orchestration of microservices, elastic tidal scaling, and software performance improvement. This solution consumes 30% less power per bit than traditional equipment, reducing customers' annual CAPEX on hardware and energy consumption.

In a radio access network, the power consumption per bit of a conventional 2T RF unit is about 20 times higher than that of a latest 64T64R massive MIMO RF unit. On the C-band, unlike 32T32R RF units, 64T64R RF units can be deployed fully on existing sites. This simplifies the network and eliminates the cost of building and maintaining new sites and adding to power consumption.

Most optical line terminals (OLTs) are deployed in CO equipment rooms. However, with technology advances and increasing demand for remote coverage and flexible deployment, some OLTs are now deployed outdoors using the AirPON solution, eliminating the need for air conditioning and fans, and thus reducing power consumption.

In addition, the optimal ambient temperature for lead-acid batteries found in telecom equipment rooms is 24 to 25°C, above which their lifespan greatly declines. Lithium batteries, however, still work in an optimal state at 35°C and are also 60% smaller than same-capacity lead-acid batteries. These two factors combined greatly reduce energy used by air conditioning.

3. Intelligent

During off-peak hours, the link load is much lower, but equipment still consumes a lot of power because traditional equipment lacks the ability to intelligently shutdown. Routers and microwave equipment can use traffic sensing to silence, shut down, or lower the frequency of RF components and circuits during off-peak hours to reduce power consumption. When the traffic volume increases, the RF components and circuits are automatically unsilenced, woken up, and boosted. Network intelligence is the foundation of decoupling network-wide power consumption from capacity and associating it with traffic.

Increasing the proportion of clean energy

Both carriers and equipment vendors can directly reduce carbon emissions by increasing the proportion of green energy purchases, and reducing the purchases of fossil fuels and fossil fuel-derived electricity. Data centers (DCs) account for an increasing proportion of carriers' energy consumption. Low PUE DC solutions can increase the power efficiency of power-hungry DCs. DCs should also be located near clean energy sources and where temperatures are low. Green power can replace thermal power, and natural cooling can replace air conditioning. A differentiated way of selecting DC locations is to replace power-grid-based high-loss power transmission with network-based low-energy data transmission. This is an effective measure to increase a carrier's percentage of clean energy use.

We still have a long way to go when it comes to environmental protection and reducing carbon emissions. We must take active measures to continously reduce power consumption and carbon emissions per unit of telecom service volume, and support the intelligent transformation of numerous industries so as to boost energy efficiency and reduce carbon emissions across the industry sector.