brief introduction
For the first time, the public's demand for mobile data exceeds the data supply capabilities of network operators. Therefore, network operators have invested billions of dollars to increase the speed of 3G and 4G mobile networks. The remote radio frequency system can reduce operating costs, while the use of FTTA (optical fiber to antenna) technology enables innovative, flexible and future-proof network installation.
Rapid development
Mobile broadband has become a reality. The data transmission speed of 3G network (UMTS) can already reach 10M, while the data transmission speed of the new 4G standard LTE (Long Term Evolution Technology) is expected to reach 100M. 3G came out in the early 21st century, when mobile communication technology was still able to meet market demand. Unlike 3G, the driving force for the advent of 4G comes from the desire of mobile communication users for data.
Since 2009, sales of ordinary mobile phones have been declining, while global smartphone sales have risen by 24%. Taking Germany as an example, the smartphone growth rate in the previous year was actually 79%. The amount of data consumed by smartphone users is much higher. Experts expect that the amount of mobile data will triple from 2010 to 2015. Due to the explosive growth of data, the current mobile communication network is approaching the capacity limit, so global mobile network operators have invested in construction 3G and 4G systems.
Unlike GSM, UMTS and LTE systems are more suitable for higher frequency bands (such as 2.1 GHz or 2.6 GHz), and the cells in urban areas are also smaller, which can meet the demand for high data traffic in these densely populated areas. However, a higher frequency will reduce the coverage of the cell, thereby greatly increasing the cost of achieving full mobile communication coverage in rural areas. If the frequency is higher, it means that more cells and investment are needed. Not only that, gigabit frequencies cannot penetrate large buildings effectively, so large buildings must be individually installed with IBC (indoor coverage) systems. Therefore, only companies that use low-frequency bands to provide services can increase the system bandwidth in an economical way. This is the benefit of "digital subdivision".
After the transition from analog to terrestrial digital broadcasting, the low frequency band within 800 MHz was released for mobile communication. The German Federal Network Administration auctioned the spectrum to Deutsche Telekom, Vodafone and O2 at a price of 4.4 billion euros in May, and each company received two frequency groupings subdivided by this number. New owners of these frequencies are obliged to achieve broadband Internet coverage in areas where broadband Internet has not yet been developed or is underdeveloped in the coming years. The development path of mobile broadband in Germany is now clear, and the construction of 4G networks will begin this year.
Current task
Due to the huge investment in new network infrastructure, mobile communication operators pay special attention to operating costs (OPEX). As the number of cells continues to increase and different network technologies (GSM, UMTS and LTE) operate in parallel, the cost of network operation and maintenance continues to rise. In sharp contrast to this trend, due to the low data communication speed and the continuous decline in voice call charges, the operating income has not increased. The forces driving operating income are high-speed Internet, data services and media content.
Network costs account for an average of 30% of the total operating costs of mobile communication operators. Rent, technical maintenance, and data backhaul costs account for about one-third of these network costs, and the remaining two-thirds are entirely electricity costs. The overall goal of the mobile communications industry is to reduce the operating costs of 3G and 4G networks.
All system manufacturers—especially Ericsson and Huawei—have committed to implementing a green "network policy" and have begun to study how to reduce the carbon dioxide emissions of mobile communication systems. "Green" base stations are energy efficient, economical and flexible, use renewable energy sources (wind and solar), and provide software-based algorithms for continuous network optimization. The latest systems for 3G and 4G mainly use remote radio heads (RRHs), and these remote radio heads are also increasingly used in "old" GSM networks. The change of technology to the remote radio frequency system has greatly saved operating costs.
Solve the cost problem
Conventional base station systems use coaxial corrugated cables to transmit high-frequency signals from the base station to the remote pole-mounted antenna. Due to the attenuation in the cable, the loss rate of the transmitted signal power is up to 50% (depending on the transmission distance and the size of the cable cross-section), and for higher frequencies generally used with LTE, the loss will increase further. These losses can also adversely affect the quality (signal-to-noise ratio) of the received signal.
The latest system uses a remote radio head (RRH) installed near the antenna (such as on a mast or building). The high-frequency signal is generated by the RRH and transmitted by the antenna with very little loss. Passive cooling of the power amplifier integrated in the RRH does not require any active cooling system (such as the cooling system required by traditional base stations). The remote radio frequency system reduces the network energy consumption by 25% to 50% (depending on the system configuration and system manufacturer's data).
Since the cooling system with high energy consumption is omitted and the power amplifier is integrated into the RRH, the volume of the latest base station is much smaller.
Since 1990, Ericsson has reduced the footprint of each base station (400 carrier units) from 23 square meters to 1 square meter now, thereby not only reducing system costs, but also reducing site rents.
The remote radio system also has the advantage of using optical fiber to transmit data between the RRH and the base station (FTTA-fiber to antenna). In traditional systems, the distance between the base station and the antenna must not exceed 100 meters (due to analog signal loss), so expensive communication space must be rented near the antenna, or expensive containers must be installed on flat roofs or outdoors. Ethernet with optical fiber as the transmission medium will not cause any signal loss when transmitting digital data between the base station and the RRH, and the maximum distance allowed is up to 20 kilometers, so the base station can be concentrated in the lower-cost communication equipment room, and Network planning will also become more flexible and modular. The link uses existing or newly installed fiber optic infrastructure to transmit data, which is simpler and much cheaper than using corrugated cables. Various reports also show that the use of optical fiber can reduce the installation time of remote RF systems,"
Operators favor
Generally, each cell is connected to the base station by three RRHs through three separate dual-core optical cables. This method is more efficient for short distance installations, but it is not ideal for running parallel systems (UMTS and LTE) and future sustainability.
An alternative method is to install a pre-assembled multi-core optical cable between the base station and the distribution box near the RRH, and then divide it into several double-core optical cables in the distribution box and connect it to the RRH. In addition to the advantages in terms of installation (that is, only one optical cable needs to be laid instead of three), this method has two other obvious advantages.First, fiber optic cables can be added at any time during the next installation (such as future LTE expansion). In the future LTE capacity expansion, the entire link has been pre-installed with optical cables, so the rest is just laying new optical jumpers from the distribution box to the LTE RRH. This method is conducive to future system expansion.Second, system expansion or upgrade often involves replacing the system manufacturer and related fiber connection technology. Although ODC© is the most widely used interface for RRH, it also uses an LC connection solution that is more difficult to install. Not only that, the future LTE system will be equipped with the so-called "Q-XCO" connector. If the system changes, the connection technology may be incompatible and it may be necessary to replace all fiber optic cables in a standard installation. By using the distribution box solution, the short jumper to the RRH can be replaced and properly adjusted-while the original optical cable connection between the base station and the distribution box remains unchanged, the installation is flexible and is not restricted by the system manufacturer.
However, due to wind loads and lack of space on the antenna mast, some network operators will not add distribution boxes. For this situation, space-saving and optimized multi-core optical cable solutions can be used, such as the Masterline Extreme solution provided by Huber+Suhner Group.
Vodafone Germany has developed the FiPro method for upgrading traditional corrugated cable systems to FTTA systems. Vodafone has partnered with Huber+Suhner Group, a leading RRH installation solution provider, to promote the use of this method. According to this method, the inner conductor of the originally installed corrugated cable will be used as an empty conduit for a multi-core optical cable. The inner and outer conductors of another coaxial cable will be used in parallel as the RRH power cord. If you use this FiPro method, you do not need to add extra work when laying cables, saving costs, such as no need to install ducts on walls or roofs, or install RRHs in difficult-to-access places. According to Vodafone, this method is more economical than traditional cable laying methods-even if the cable laying distance is not long.
The last optional FTTAinstallation method is the so-called "hybrid solution"-that is, a copper/optical hybrid cable is used for power supply and data connection. Although these solutions appear attractive, they are difficult to implement and uneconomical. This type of solution is only worthwhile in certain situations, such as the high rental cost of each cable. Vodafone Germany has developed the FiPro method for upgrading traditional corrugated cable systems to FTTA systems. Vodafone has partnered with Huber+Suhner Group, a leading RRH installation solution provider, to promote the use of this method. According to this method, the inner conductor of the originally installed corrugated cable will be used as an empty conduit for a multi-core optical cable. The inner and outer conductors of another coaxial cable will be used in parallel as the RRH power cord. If you use this FiPro method, you do not need to add extra work when laying cables, saving costs. For example, you do not need to install ducts on walls or roofs, and you do not need to install RRHs in difficult-to-access areas. According to Vodafone, this method is more economical than traditional cable laying methods-even if the cable laying distance is not long.
in conclusion
Remote radio frequency systems provide network operators with significant cost and technical advantages, so the number of remote radio frequency systems installed last year exceeded the number of traditional systems for the first time. Experts expect this trend to continue and accelerate. In addition, experts also expect that all newly developed systems of system manufacturers will be based on remote radio frequency systems.
FTTA's network structure is innovative and flexible, which helps to further reduce operating costs and ensure the sustainability of the network in the future.
