Abstract
The chapter provides information as a first step for individuals who are thriving to get a bird's eye view of the aspects underlying the optical networking in the context of 5G technology. Apart from capacity requirement challenges targeted by 5G coverage, it requires a lot of fibers to be successfully provisioned to achieve formidable performance goals of 5G such as diversified capacity requirements, availability, and coverage issues. The goals could be achieved by the underlying optical network with a greater number of interconnected fiber paths. In 5G, the requirements of reliable and ultra-low latency services required at the access side of a network shape up the research and evolution of underlying optical segments spanning from core to access part of the network. The reconfigurability and security issues of the present mode of optical communication need to be addressed, and the proposals given by the researchers are summed up. The chapter includes a general framework and theoretical concepts behind machine learning and software defined networking paradigms.
TopSpace Division Multiplexing In Optical Networks
A highly flexible, adaptive high-capacity front haul with desirable power conservation becomes necessary attributes to be supported to cater to the requirements of 5G specifications. The optical spatial multiplexing is a promising member proposed to be included in the Next Generation Passive Optical Networks NGPON. Lagkas et al. (2020) have proposed a minimized energy consuming 5G front haul with an emphasis on assignment of optical resources. The work approaches spatial multiplexing incorporating the optical beamforming (OBFNs), Multicore fibers (MCFs) and Spectrally Spatially Flexible optical network propositions modelled as optimization problems and evaluated through simulations for their effectiveness.
In 5G architecture, the functionality of Baseband Unit (BBU) in a BBU pool is taken care of centrally by the Cloud Radio Access Network (C-RAN) by integrating the front haul, backhaul telecommunication infrastructures and radio access. Wireless connectivity for the mobile devices are provided by the Remote Radio Heads (RRHs). As a convergence of C-RAN, the traffic collected is delivered through the PON of the Optical Distribution Network (ODN) front haul. This enables the system to have high scaling capabilities with better adaptation to dynamic traffic situations. The Central Office (CO) where BBU pools are resident supports multiple operators and multiple services, while supporting Optical Line Terminals also. Through Remote Nodes (RNs), with dedicated fiber links the RRHs are reached. Other options of front haul design are also proposed to lower energy consumption, end to end delay and complexity by migrating the tasks carried out at the RRH to the Central Office. By adopting Digital Radio over Fiber (DRoF) evolved as eCPRI and Next Generation Front Haul Interface (NGFI), processing of wireless data at baseband and transmitted over optical fibers with addition of Medium Access Control layers processes to RRH sites.
Key Terms in this Chapter
Optical Beam Forming Networks (OBFN): Communication networks which have the ability to focus, shape and steer the light signals. Capable of manipulating or indirectly change a radio frequency on an optical carrier.
Space Division Multiplexing (SDM): A multiplexing technique used to transmit several independent channels separated in spatial dimensions, adopted in MIMO wireless communications and fiber optic communications.
Baseband Unit (BBU): A telecommunication network device used to interpret and process baseband signals in telecom systems. Baseband signals are the original frequencies of transmissions prior to being modulated. A BBU typically connects to transceivers – Remote Radio Units (RRU) through wired or wireless connections.
Wavelength-Selective Switches (WSS): In optical networks, reconfiguration of traffic and bandwidth sharing over the optical layer is taken care of by the WSS. A WSS uses a diffraction grating to separate wavelengths and a switch section with an array of optical ports.
Passive Optical Network (PON): Fiber optic technology to cater to multiple end pints from a single source. The word “Passive” signifies the usage of an unpowered splitter(passive) which transmits data from a service provider to multiple customers, each customer being connected with the splitter through optical fiber cables. A GPON is capable of high-speed Gigabit transmissions.
Radio Access Network (RAN): A telecommunication network infrastructure that connects individual user devices to other parts of a network through a radio link. RAN includes base station and antennas that cover a specific region according to its capacity, design, and propagation.
Software-Defined Networking (SDN): A networking approach that envisages communication with underlying hardware infrastructure using software based controllers or Application Programming Interfaces to direct traffic on the network.
Wavelength-Switched Optical Networks (WSON): WSON are Wavelength Division Multiplexing (WDM) networks which consist of switching elements that perform switching depending on the wavelength of signals transported through an optical fiber.
Routing and Wavelength Assignment (RWA): In optical Wavelength Division Multiplexing (WDM) networks, with an aim for maximizing the number of optical connections, wavelengths are assigned for connection requests, i.e., light paths are assigned to carry traffic over optical carriers according to specified routing schemes.
Common Public Radio Interface (CPRI): Wireless interface specification for transport, connectivity and control communication between BBUs and RRUs of cellular wireless networks. An I/Q interface protocol for communication between towers and base stations for various standards such as GSM, WCDMA, LTE, etc.
Multiple Input Multiple Output (MIMO): Usage of multiple transmitters and receivers to transfer more data at the same time. MIMO technology uses spatial dimensions and smart antennas thus utilizing diversity and multipath to achieve higher speeds of data transfer.