Have you ever participated in popular concerts, major competitions, or even work meetings, but couldn't upload selfies, check Facebook updates, or read and send emails? The really frustrating part is that you have the signal bar, but your app just "stuck". So, you lifted your phone higher, hoping that an extra meter height would magically let your content pass, but the result was once again shattered.

Vice President, Strategy and Business Development, Head of Transportation

Vice President, Strategy and Business Development, Head of Transportation

Vice President, Strategy and Business Development, Head of Transportation

The reason for this is simple. Too many people try to access and use the same frequency spectrum at this location, thus overloading the radio site. This is a simple case of a mismatch between supply and demand.

The remedy is equally simple. The communication service provider (CSP) only needs to provide more radio capacity at this location, "look", the problem is solved! However, as we all know, this is easier said than done.

CSP has adopted a variety of methods to resolve this situation and satisfy subscribers. In some cases, CSPs will deploy temporary cell sites to enhance the permanent network by using cellular on wheels (COW) or cellular on light trucks (COLT). In other cases, users can choose to look for Wi-Fi connections (but this is the subject of other blogs). The third method that is becoming more and more popular is RAN densification. In other words, deploy small cells at these target locations and implement dynamic spectrum sharing to improve RAN performance. Sounds great, right?

However, adding new miniature radio/remote radio unit (RRU) and related gNB to specific locations such as stadiums, venues, shopping malls, and campuses will bring a series of new challenges. One of the main challenges is connectivity-basically, how to connect all these small cells to the network from these specific locations. This is harder than you think.

why is that. Many stadiums, stadiums, shopping malls, hospitals, corporate headquarters, etc. were designed and constructed more than 30 years ago. For example, the average age of professional stadiums in the National Football League is 31 years old. The age of college football stadiums is even older, with an average age of 54 years. National Hockey League stadiums are 30 years old, while the average age of Major League Baseball stadiums is 50 years. When most of these structures are designed and built, consumers cannot use 2G mobile network services! As a result, these locations lack the digital infrastructure needed to connect to the latest RAN technology, especially fiber optic cabling. In addition, no two buildings are the same, so methods that may be applicable to one location may not be applicable to another location. 

In response to user needs for enhanced mobile network coverage and performance, distributed antenna systems (DAS) have been widely deployed in these types of locations for decades. The main benefit of DAS to owners is that DAS is operator-neutral. This means that the system can be shared by multiple CSPs, and it has been proven that it can be extended using various RAN and private network frequencies.

However, 5G technologies such as 5G NR in millimeter waves, mid-to-high frequency band radios, and high-end MIMO active antenna systems (for example, up to 64T64R) will be difficult to achieve through passive/active DAS. This means that the prospects and advantages of 5G, from enhanced mobile broadband to new network-based applications, such as the Internet of Things (IoT), real-time AR/VR and immersive media may not be available on existing DAS systems. About 5G use cases For more information, please refer to: Consumer Lab

As RAN densification and centralization bring outdoor small cells and indoor RAN options to stadiums, stadiums, shopping malls, hospitals, and corporate headquarters, what is the best way to connect all these RAN components? The good news is that although these physical buildings are older and most predate the availability of large-scale mobile services, their fiber optic cable factories have been upgraded over the years. However, with the advent of LTE-Advanced and 5G, there are usually not enough extra fiber pairs available for the new RAN.

Based on Ericsson's experience in designing and deploying RAN networks for stadiums, stadiums, shopping malls, hospitals and corporate headquarters, we have solved this RAN connection problem through the Optical Fronthaul 6000. For example, we recently upgraded the Baku Olympic Stadium to ultra-high capacity using Ericsson Elastic RAN transmitted through the Ericsson Fronthaul 6000 network. Ericsson's Fronthaul 6000 provides services for all RAN connections through an excellent and flexible 5G optical platform. It is a flexible and cost-effective solution for Ethernet, CPRI and eCPRI transmission, and can be used alone or together. It provides market-leading fiber density, 25G capacity, and negligible latency to achieve leading 5G radio performance, even in the densest deployment areas where RAN centralization plays an increasingly important role.

Ericsson provides multiple options for RRU fronthaul based on performance, scale and cost. When building a site fronthaul network, you need to use the right tools to accomplish this task. The options in the prequel kit include:

In actual deployment, it is not uncommon to use a combination of multiple technologies to meet the needs of a specific location.

Passive light fronthaul. Passive optical fronthaul is very suitable for deployments optimized for space and power (for example, small base stations) because of its small size and high cost-effectiveness. Passive solutions are very flexible and can be installed in poles, hand holes or small honeycomb enclosures to keep them out of sight. Passive fronthaul does not require any additional power supply. The color optics only need to be directly inserted into the RRU and corresponding gNB, and connected through the optical add/drop filter. The filter is independent of protocol and bit rate and can transmit any combination of CPRI, eCPRI and/or Ethernet services. However, for optical connection failure and performance monitoring, you must rely on radio and baseband to monitor passive optical infrastructure. Passive fronthaul also requires good planning, management and installation to ensure correct alignment of ports and wavelengths.

Active optical fronthaul. Active fronthaul is usually used in large sites with many radios, or sites where fiber optic monitoring and management is critical. Generally, in an active solution, the transponder can convert up to 24 gray services to specific DWDM wavelengths and multiplex them onto a single fiber bundle. This makes it easy to convert a previously installed radio to Dense Wavelength Division Multiplexing (DWDM) without changing the optics in the installed radio. The main advantages of active fronthaul are integrated optical performance and fault management capabilities, as well as a clear boundary between the DWDM transmission domain and the gray optical radio domain.

Semi-passive/active fronthaul. This is a hybrid deployment solution that balances the advantages and challenges of the two methods. Here, the active transponder is placed at the central site (semi-passive) or remote site (semi-active) where the gNB is located. In the semi-passive solution, the pluggable DWDM SFP+ plugs directly into the radio, and the transponder is placed on the gNB hub. The semi-passive configuration allows to simplify the OA&M of the transmission network, provide a single point of access for DWDM operation, and be compatible with any baseband and router interface, while keeping the cell site small. In the semi-active fronthaul, the pluggable DWDM SFP+ is inserted into the baseband of the hub, and the transponder is placed close to the RRU. The semi-active configuration allows cost and floor space savings at the gNB hub site, which may be important when space in a colocation cage or communication room is limited. Compared with passive solutions, it retains many advantages of fully active solutions and can simplify OA&M at remote sites.

Learn how Ericsson's Fronthaul 6000 provides today's 5G RAN connectivity.

Optical fronthaul: DWDM for optical RAN connection-Ericsson

How to upgrade RAN in the face of optical fiber network restrictions

Use packet technology to build an efficient fronthaul network

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