Mobile backhaul refers to the section of the telecom network that transports cellular traffic from base stations at cell towers to the nearest traffic switching center. While multiple backhaul options are available today (optical fiber, microwave or copper), mobile operators are gravitating to optical fiber as the physical medium of choice especially with the deployment of 4G/pre-5G technologies and new cloud-architectures, massive IoT (internet of things) and virtualization.
Investment Protection: With the rapid emergence of new mobile generations (4G, 5G), it becomes critical to use backhaul equipment that are flexible enough to operate efficiently irrespective of the radio access network (RAN) deployed. The equipment should evolve smoothly and be capable of scaling suitably to address the changing capacity, latency or coverage requirements.
Advanced Capabilities: 4G/5G standards incorporate a plethora of advanced features such as carrier aggregation, coordinated multipoint (CoMP), network slicing, mobile edge computing (MEC), X2/eX2 interfaces for fast hand-offs that significantly advance the capabilities expected from backhaul networks. The advent of 4G and 5G calls for stringent latency requirements and greater flexibility in the treatment of data and signalling traffic while continuing to lower the transmission objective of reducing the overall cost per bit.
Converged Backhaul: Large mobile operators evolving from TDM-centric 2G/3G to Packet-centric 4G/5G radio access networks typically build a converged backhaul network that is optimized to transport both circuit and data traffic. Since the proportion of data traffic in 4G/5G is significantly larger than circuit traffic, these operators require a mature circuit emulation solution along with field-proven MPLS-TP and Carrier Ethernet implementations. The need for precise packet synchronization for LTE-TDD, TDM and video services using SyncE/1588v2 standards are also essential for an excellent quality of experience.
Emergence of Fronthaul: 5G is introducing new radio access architectures such as C-RAN (centralized RAN) using new protocols such as CPRI/eCPR to connect multiple remote radio heads at street level to a centralized cloud-resident baseband unit at the macro base station. Optical fiber is the popular choice for this “fronthaul” network and imposes additional demands in terms of latency, jitter, scalability and connection bandwidth on the backhaul.