5G will be revolutionary rather than evolutionary with the advanced DWDM/Optical technologies
The telecommunications industry and particularly service providers have faced a dramatic and very rapid increase in the volume and type of data their systems must handle. Networks originally built to transmit sound waves as electrical signals from one phone to another are now faced with managing data and video in real-time from many devices. Since the introduction of the Internet and creation of the Worldwide Web in the 80s and early 90s, within approximately 30 short years, 5G wireless technology is now rolling out and rapidly moving toward the IoT through which virtually all devices can theoretically be interconnected.
Fiber optics and optical communications in general have had significant impact on the telecommunications industry and will continue to do so, with light as a carrier enabling much higher data transmission rates over greater distances and with lower losses compared to electrical signals. To encode data into light to transmit it and decode it back into electrical signals upon receipt, optical communications rely on optical transceivers.
Why is DWDM?
Dense Wavelength Division Multiplexing (DWDM) is transceiver technology developed around 20 years ago that has made optical telecommunications even better. It dramatically increases bandwidth (essentially the amount of data that can be transmitted) over existing fiber networks. Simply put, data from various signals are separated and encoded on different wavelengths and put together (multiplexed) in a single optical fiber. At the receiving end, the wavelengths are separated out again and reconverted into the original digital signals. In other words, DWDM allows different data streams to be sent simultaneously over a single optical fiber without requiring new cables to be laid. It is ‘dense’ reflecting the large number of signals that can be packed in a single fiber. Furthermore, because DWDM connections can be amplified, they can transmit data across very long distances.
The tremendous expansion in data volume afforded with DWDM can be seen in comparison with other optical methods. A standard transceiver, often called a grey transceiver, is a single-channel device — each fibre has a single laser source. You can transmit 10 Gbps with grey optics. Coarse Wavelength Division Multiplexing (CWDM) has multiple channels, although far fewer than possible with DWDM. For example, with a 4-channel CWDM you can transmit 40 Gbps. DWDM can accommodate up to 100 channels. At that capacity, you can transmit 1 Tbps or one trillion bps — 100 times more data than grey optics and 25 times more than CWDM.
While the volume of data transmitted with DWDM is impressive, demand will continue to grow as we move toward IoT and 5G. Adding additional optical transceivers with different wavelengths to a fixed-wavelength DWDM system can significantly increase cost. Tunable DWDM transceivers allow to control the wavelength (colour) that the laser channel emits adding flexibility and reducing cost. Few companies supply the technology.
5G Technology Development and Transport Requirements
Requirements on 5G transport are influenced by changes in 5G services and network architectures. 5G service requirements directly affect the technical specifications of transport networks, including bandwidth, latency, and clock precision. Architectural changes of 5G wireless networks and core networks lead to changes in transport network architecture, and raise new requirements for network functions, including network slicing and enhanced routing and forwarding.
Evolutionary Trends of 5G RAN Architecture
The introduction of high bandwidth and low latency apps into 5G networks means that radio access network (RAN) architecture needs to be improved.
5G RAN networks will evolve from the two-level structure of a baseband unit (BBU) and a remote radio unit (RRU) present in 4G/LTE networks, to a three-level structure that includes a centralized unit (CU), a distributed unit (DU), and an active antenna unit (AAU). This restructuring of 5G RAN is shown in Figure 2. The part of the original BBU that is not real-time is split and redefined as a CU, which processes the protocols and services that are not real-time. The original RRU and some physical-layer processing functions of the original BBU are combined into an AAU. The remaining functions of the original BBU are redefined as a DU, which processes physical-layer protocols and real-time The 5G transport network consists of three parts, namely, fronthaul, midhaul, and backhaul. 5G services require high bandwidth and low latency. Optical transport networks have inherent advantages in providing high bandwidth, low latency, and one-hop connection capabilities for carrying 5G services.
5G data throughput requirement
5G-Oriented OTN-based Transport Solution
The 5G transport network consists of three parts, namely, fronthaul, midhaul, and backhaul. 5G services require high bandwidth and low latency. Optical transport networks have inherent advantages in providing high bandwidth, low latency, and one-hop connection capabilities for carrying 5G services.
A centralized wireless device (DU or CU+DU) can be deployed at a central office (CO). The transport device at the CO aggregates fronthaul traffic to the wireless device of this node or uploads midhaul and backhaul services to the upper-layer transport device. As an integrated access node, the CO must support various types of access services and provide high bandwidth and low latency. Packet-enhanced OTN devices can fully meet these requirements.
Fronthaul solution by NOKIA:
Optical Transceivers For 5G Networks
With the maturity of 5G technology and the deployment of base stations, the advance construction and upgrade of the bearer network will drive the demand for optical devices of the communication network to explode.
5G Bearer Network Topology:
5G bearer network can provide connections for 5G wireless access and core networks. Its network architecture and bandwidth have been changed greatly to adapt to larger bandwidth, lower latency and more connection services compared with 4G networks.
5G has moved part of the physical layer of the original BBU (baseband unit) in the 4G era to AAU (active antenna unit). Also, the interface has been changed from the original 100Gbit/s CPRI to 25Gbit/s. And the non-real-time functions of the BBU are moving up to the CU (centralized unit) to make preparations for the clouding network. In this way, the DU (distribution unit) is the only part of the BBU. In other words, the 5G access network has evolved from the two-tier architecture of the BBU and RRU to the three-tier architecture of CU, DU, and AAU. This not only ensures high bandwidth and low latency of the network but also contributes to flexible scheduling, network protection, and management control.
The applications of 5G front-haul, mid-haul and back-haul transmission are basically different, thus the requirements for transceivers and transmission distances are also varied.
5G Front-Haul Technology
The 5G front-haul transmission is strict about the bandwidth and latency (which is below 100µs), so 25Gbps eCPRI interface is considered as an optimal choice for the 5G front-haul network. Considering the convenience and efficiency of network construction, the initial 5G front-haul connection is based on fiber direct connection, which is supplemented by the passive WDM connection and the active WDM/OTN/SPN connection. Among them, fiber direct connection is easy to maintain but will consume more fiber resources. As a supplementary solution, WDM connection can save fiber resources and have a longer transmission distance than fiber direct connection, but the cost is expensive.
Passive WDM connection can multiplex several wavelengths and transmit them on a pair of or a single fiber to connect multiple AAUs to DUs to save fiber. However, it brings difficulties for the network administrators to make daily maintenance because of the technical complexity. Generally, the 10G or 25G colored light transceivers (WDM modules) are applied for this connection with a 10km and 20km transmission distance.
5G Mid-Haul & Back-Haul Technology
Since the requirements of bandwidth and networking flexibility are basically the same for 5G mid-haul and back-haul networks. They can utilize the same technology for transmission, like IPRAN (Internet Protocol Radio Access Network), PTN and OTN technology, etc.
5G mid-haul/back-haul networks cover the access layer, aggregation layer, and core layer of the MAN (metropolitan area network), and the optical transceivers used in the core layer are similar to those used in existing transmission networks and data centers. Among them, the 25G/50G/100G grey light or colored light optical transceivers will be mainly applied for the metro access layer network, and the metro convergence and core layer network will mainly use 100G/200G/400G DWDM colored light optical transceivers.
Why Auto-tunable DWDM transceivers is a game-changing technology-A latest innovation by Infinera
Auto-tunable DWDM transceivers are changing the way service providers expand and deploy 5G networks.
Auto-Tunable DWDM Transceivers: Main Features
· Tunable via software command to 96 frequencies in the DWDM spectrum
· Automatic “hand-shake” between transceivers, tuning to correct frequency
· Intelligent detection of signal loss and reconnection
800G capacity per optical channel over longer Distances-Innovation by Infinera
Redefining, How Optical Networks Are Built with Infinera XR Optics
Integration of IP and Optical Network to meet 5G requirement-An innovation by NOKIA
Optical Layer restoration for mission critical services with NOKIA’s 1830 PSS platform
Summary:
Optical transport networks are critical to the modern economy and society. With the popularization of 5G application and network cloudification, transport networks are facing surging traffic and increasing requirements for ultra-low latency, high reliability, high flexibility, and intelligence. The existing network architecture cannot meet these requirements.
For operators, 5G is an important service, and the transport network must support the unified transport of all services. Based on the advantages of OTN technologies, such as high bandwidth and transparent transmission, the OTN/WDM multi-service transport network provides unified and integrated transport of various services, including 5G, fixed broadband, cloud, and government and enterprise private line services. OTN has a mature industry with comprehensive standardization. OTN can meet most 5G transport requirements, including those for high bandwidth, low latency, high-precision clock, and high reliability. Technological evolution based on OTN is efficient, and can balance both risk and cost to enable 5G transport.
Thank you!!
Monowar Hossain
HOD, Microwave Unit (Planning & Operation)
VEON, Bangladesh
Mobile: +8801962424691
E-mail:monowar.hossain@banglalink.net
Originally published at https://www.linkedin.com.
