China Mobile's Cai Qian: 5G transmission is ready, SPN is about to usher in a new era of bearer

At present, 5G has become a hot topic in the industry. In the upcoming era of the Internet of Everything, 5G is a very critical technology. Compared with 4G, 5G has more diverse business scenarios, which brings huge challenges to the 5G bearer network. 5G transmission, bearer first is not just a slogan. The current deployment time of the 5G bearer network is very tight. As an operator that innovatively launched the SPN (sliced ​​packet network) technology, China Mobile shoulders a more important role. Therefore, China Mobile is working overtime to continuously promote the commercialization of the 5G bearer network.

[[245257]]

Cai Qian from China Mobile Research Institute said in an interview with Mobile Labs that with the joint efforts of partners from all links of the industry chain, the SPN pilot has a network environment and will soon start end-to-end key function and technology verification to form end-to-end network capabilities. In 2019, large-scale pilot tests for commercial use will be further carried out.

Cai Qian, China Mobile Research Institute

The window of change: How 5G bearer can overcome four obstacles

With the mature commercialization of 4G networks, mobile broadband is gradually changing people's lives. At the same time, the footsteps of 5G are getting closer and closer, and the formulation of 5G standards and research on key technologies are also gradually accelerating. On the road to 5G, bearer networks come first. As an end-to-end network connecting wireless and core networks, the importance of bearer networks on the road to 5G commercialization is self-evident. So, what needs and challenges does the 5G bearer network face?

Compared with TD-LTE, the three major business scenarios of 5G have many rigid requirements for the bearer network in the long run. In addition, as equipment is facing upgrading and new technologies emerge, the industry generally believes that the window for 5G bearer technology transformation has arrived. However, from the perspective of development, there have always been four major factors affecting the 5G transmission network architecture.

• The changes in the 5G RAN architecture have a great impact on the transmission network architecture. The 3GPP 5G RAN functional segmentation defines a two-level architecture of CU and DU, resulting in a variety of site types in the 5G stage. It is no longer mainly backhaul, but fronthaul, midhaul, and backhaul networks will be equally important and support multiple services.
• Changes in the 5G CORE architecture have a great impact on the transmission network architecture. UPF and MEC in the 5G network are flexibly deployed according to specific business needs. The traffic between MECs needs to be forwarded nearby, and the L3 function of the metropolitan area network needs to be sunk to the aggregation layer or even the access layer. The L3 domain is increased, which has a great impact on the networking.
• 5G network slicing and low-latency service requirements of vertical industries have a great impact on network architecture. It is necessary to reduce end-to-end latency, require each node to support extremely low forwarding latency, and support both hard isolation and soft isolation to achieve hard and soft slicing.
• 5G is based on the SDN architecture, and it is necessary to consider introducing controllers and orchestrators. It is necessary to achieve decoupling of each layer through standard interfaces and information models. At the same time, it is necessary to consider the performance issues of the control system when managing the large three-layer network.

According to Cai Qian, China Mobile has conducted in-depth research on 5G service requirements and technology development, and has put forward three 10-fold requirements for 5G bearer networks: 10-fold capacity increase, 10-fold performance improvement, and 1/10 reduction in cost per bit/s. To this end, China Mobile has innovatively proposed the Sliced ​​Packet Network (SPN), which uses innovative technologies at the physical layer, link layer, and forwarding control layer to meet the needs of a comprehensive service transmission network including 5G services.

Demand and technology jointly drive 5G transmission reconstruction

"For technology to advance, it must first be driven by demand." Cai Qian pointed out that the emergence of SPN is mainly aimed at the entire transmission network. The urgent demand for 5G and the next-generation transmission network and the development of technology jointly promote the reconstruction of 5G transmission, which also constitutes the two major driving forces of SPN.

China Mobile has started relevant technical research since 2016. From demand to technical solution selection, and until the final decision is made, each link will go through multiple rounds of internal discussions and competition between professionals. Since the next-generation transmission network is centered on 5G bearer and takes into account the comprehensive bearer of home and customer services, China Mobile believes that SPN is the preferred solution for building a unified and efficient comprehensive service transmission network in the future.

Cai Qian said, "The entire SPN technology is divided into a three-layer architecture, which solves the six major challenges of 5G through one technology and meets various new requirements. The slice transport layer STL can realize slice physical layer encoding and decoding, adopts cost-effective 25GE, 50GE, 100GE, 200GE, 400GE and other large-capacity Ethernet interfaces, and supports color optical DWDM; the slice channel layer SCL realizes the networking processing of slice Ethernet channels, supports low-latency forwarding, network slice hard isolation, etc.; the slice packet layer SPL realizes the routing processing of packet data through SR-TP and MPLS-TP, supports flexible connection, and meets L2/L3 VPN and CBR service requirements."

To address the three-layer problem, SPN introduces SR-TP to implement scientifically manageable L3 tunnels, build an end-to-end L3 deployment business model, and introduce a high-performance centralized control L3 control plane; for sharding and ultra-low latency services, SPN introduces FlexE interfaces and converged switching architecture. At the same time, SPN manages and controls the converged SDN platform to achieve logical abstraction and virtualization of network element physical resources, such as forwarding, computing, storage, and other resources to form virtual resources, and organizes virtual networks on demand, presenting a network form of "one physical network, multiple networking architectures".

[[245258]]

Cai Qian pointed out that SPN can realize the unified bearing of fronthaul, midhaul and backhaul. For the midhaul/backhaul solution, the same network can be used to uniformly bear the midhaul/backhaul, meet the needs of different RAN side network element combinations, support end-to-end network hard slicing through FlexE channels; sink L3 functions to the aggregation layer or even the access layer; introduce 50GE (BIDI) to the access layer, and introduce 100G/200G color optical solutions to the core aggregation layer. In the fronthaul, Cai Qian believes that for areas with abundant access optical fibers, it is recommended to use the optical fiber direct drive solution for bearing, and for areas with insufficient access optical fibers and high construction difficulty, the fronthaul SPN color optical solution can be considered for bearing.

5G transmission is ready, and SPN's "circle of friends" is growing

Network transformation and 5G have brought great challenges to operators, both in terms of technical capabilities and management and operation models. While China Mobile is selecting SPN technology that is suitable for its own network characteristics and development plans, it is also actively participating in guiding the industry chain and jointly promoting the application of related technologies.

"From October 2017 to August 2018, China Mobile completed the SPN laboratory test phase. According to Cai Qian, "the laboratory test phase completed the SPN laboratory test of major transmission equipment manufacturers - Huawei, ZTE, and FiberHome, including 5G backhaul and fronthaul multiple types of SPN equipment, including 2 types of fronthaul equipment (client-side equipment and central office equipment), 3 types of backhaul equipment (access layer, aggregation side and core side equipment), a total of 12 types, nearly 100 SPN devices. The laboratory test content includes SPN functional testing and SPN networking testing, covering the key technical functional points of the SPN technical system SPL layer, SCL layer and STL layer, and completing 6 categories of test cases and more than 100 major items. "

Since June this year, SPN has shifted from experimental testing to large-scale testing. "From the current early tests, major manufacturers have met our requirements. Starting from Q4 2018, the entire laboratory test will shift to the live network cities of SPN transmission, and tests will be carried out in the five major cities of Guangzhou, Hangzhou, Shanghai, Wuhan and Suzhou."

The global 5G competition has begun, and major communication operators are striving to gain the right to speak on 5G, but it is not easy to achieve commercialization from standards in the short term. In terms of standards, China Mobile has promoted 5G transmission SPN in the international standard ITU-T, industry standard CCSA, and enterprise standard, established SPN in ITU-T and CCSA, and completed the formulation of 5G transmission technical specifications and test specifications.

But this is far from enough. Due to the differences in the current status of the 4G bearer networks of the three major operators, the technical evolution routes of 5G bearer will be different. The determining factors for the selection of technical solutions need to focus on the comprehensive network cost and industry maturity. Cai Qian called on Chinese operators and enterprises to focus on the overall situation and form a joint force.

[[245259]]

As the saying goes, the more friends you have, the easier your life will be. Cai Qian said, "China Mobile's 5G transmission is ready, and SPN is about to usher in a new era of bearer technology." In fact, this can also be seen from the growing circle of friends of SPN.

THE END

In terms of chips, Huawei, ZTE, and FiberHome have completed the development of their own chips, and Broadcom, Centec, and others have released SPN chips. In terms of modules, many domestic and international manufacturers have launched large-capacity gray light and color light modules. In terms of test instruments, mainstream instrument manufacturers have released test instruments that support SPN, and Spirent, IXIA, VIAVI, and others support SPN testing. China Mobile's SPN technology has won the attention of the industry due to its excellent functions and performance, and many foreign operators and equipment manufacturers have shown great interest in SPN.