5G Flexhaul: Building a Flexible, Unified, and Cost-effective 5G Transport Network

To achieve a seamless transition to 5G in the next few years, it is crucial for operators to start designing future-proof transport networks that will support the anticipated needs of users for next-generation communication services. As a global leader in the research on 5G, ZTE believes that operators need to address new challenges based on the key capability indices proposed by ITU-R for eMBB (enhanced mobile broadband), uRLLC (ultra-reliable and low latency communications) and mMTC (massive machine-type communications) services:

Source: Recommendation ITU-R M.2083-0

  • Significant Bandwidth Improvement

5G networks need to provide users with over 100 Mbps data rate anywhere, any time. In some hotspot areas with high capacity, networks need to support up to 1 Gbps rate and over 10 Gbps peak rate per base station. The ultra-high access rate will lead to an order of magnitude increase in transport network bandwidth demands.

  • Ultra-low Latency

5G covers various applications such as mobile communication, UHD video, cloud office and games, VR/AR, intelligent wearing, smart home, smart city, industrial automation, automatic driving, and highly reliable applications (e.g. mobile health care), which have different latency requirements. The uRLLC scenario requires the lowest latency. As suggested by NGMN, the one-way E2E latency in uRLLC scenario should be less than 1ms. 3GPP defines uRLLC wireless air interface latency as 0.5ms. Besides, there is latency in core network, and then the remaining latency budget for transport network is extremely low. These requirements present huge challenges to both 5G fronthaul and backhaul networks.

  • Flexible Networking and Network Cloudification

In ultra-dense networking, 5G base stations have much closer coordination than they do in the 4G era; at the same time, 5G traffic models become more complicated, both of which require transport networks to flexibly forward traffic from the base stations to micro cloud, edge cloud, core cloud as well as the traffic between the clouds. Meanwhile, the transport network integrates SDN (Software Defined Network) technologies into network architecture design. Operators can optimize the network resources with the view of entire network; deploy network element functions at any position in the network, to fulfill programmable network connections.

  • Satisfying Differentiated Demands Cost-Effectively

To be competitive in the marketplace, 5G operators need to minimize network investments and improve the Return On Investment (ROI), while meeting the huge surge in traffic. In order to be cost-effective, 5G operators need to manage differentiated service demands in real-time in multiple scenarios.

ZTE conducts a series of research work on 5G transport. Based on ZTE’s research on 5G transport network requirements, and our deep understanding of operators’ transformation and development needs, we are releasing the 5G Flexhaul solution at MWC 2017, pioneering an innovative approach for operators to build a flexible, unified, and cost-effective 5G transport network architecture.

  • FlexE-based IP+Optical Solution

In ZTE’s 5G Flexhaul solution, the access layer comprises of a series of IP+Optical integrated physical network elements, the result of a deep integration of packet and optical technologies.

The essence of access layer IP+Optical solution is FlexE over DWDM. Independent wavelength is allocated to each service at add/drop node through the inbuilt DWDM unit. Multiple network side interfaces are bound based on FlexE to provide higher bandwidth. At the same time, the services irrelevant to the node are directly transmitted through by optical layer to achieve the latency to near zero.

The unique ZTE Flexible IP+Optical solution provides flexible bandwidth, making it easy for operators to expand their bandwidth based on the traffic volume at each access node at different stages of 5G development in a cost-effective way. It can help operators to make smaller investment but get a powerful expansion capability to Tbps level at the initial stage of 5G deployment.

  • Ultra-low Latency

ZTE’s 5G Flexhaul solution provides differentiated latency guarantee for different services. Ultra-low latency service demands can be satisfied by dealing with three aspects: network architecture, service path and equipment processing.

The flat network architecture can be fulfilled by introducing optical layer technology so that the number of forwarding nodes is decreased and the entire network latency is effectively reduced. Low-latency forwarding path automatic discovery can be implemented based on SDN architecture. At the same time, independent transport slices are built for low-latency services. In this way, strict classification and precise control are implemented in latency guarantee, bandwidth provisioning, and performance indices. Two solutions of fast forwarding and regular forwarding are provided for the transmission equipment to guarantee differentiated latency based on the demands of different services.

  • Flexible Traffic Engineering

As the key technology of network architecture innovation, SDN is the foundation of 5G Flexhaul’s powerful traffic engineering capabilities. The intelligent perception of network traffic can be implemented by the real-time traffic monitoring unit built in the controller to implement flexible bandwidth adjustment for fluctuations in network traffic. With total bandwidth unchanged, based on the service status, ZTE 5G Flexhaul can automatically adjust PIR (Peak Information Rate) and CIR (Committed Information Rate). 5G Flexhaul effectively supports operators in new service innovations, generating additional revenue opportunities and deliver maximum returns for fixed costs.

  • Flexible Network Architecture

In the era of 5G, both C-RAN and D-RAN architectures may emerge. The traditional wireless transport network may overlap physically with both 5G fronthaul and backhaul networks. 5G Flexhaul solution uses FlexE to implement unified transport of packet fronthaul and backhaul interface. Meanwhile, based on SDN controller, it can implement unified management and O&M of fronthaul and backhaul networks, so as to build up the unified transport of fronthaul and backhaul networks. This way, the planning, provisioning, and O&M of the entire network are optimized in a unified way. 5G Flexhaul can effectively avoid the interoperation between the heterogeneous networks, and help operators build 5G transport networks with low TCO.

At MWC 2017, ZTE is also exhibiting the first 5G fronthaul & backhaul unified transport pre-commercial equipment in the industry – ZXCTN 6180H. With an integrated architecture, ZXCTN 6180H has small size, large capacity, low power consumption, and multi-service access. It provides various service access capability, supports interfaces with the rate from E1, STM to 25G/100G, and meets all the 5G network evolution demands.

As the era of 5G approaches, operators need to accelerate transport network innovations to meet new opportunities and challenges. ZTE’s industry-leading innovations will help operators build the most advanced and cost-effective transport networks.