Defining 5G at MWC 2015 – New Air Interface, New Architecture, and New Operation

Huawei, a leading global information and communications technology (ICT) solutions provider, showcases its 5G network architecture and air interface technology set for the first time at the 2015 Mobile World Congress (MWC). 

At the 2014 Global Mobile Broadband World Forum held in Shanghai this past November, Huawei’s rotating CEO Mr. Zhijun Xu proposed that 5G must focus on the development of the Internet of Things (IoT) and make breakthroughs to support the expansion and enhancement of mobile Internet. The application of 5G in IoT and vertical industries will bring more market space and present business opportunities to operators. In addition, expanded and enhanced mobile Internet services will help further improve the user experience, strengthen user stickiness, increase the average revenue per user (ARPU), and guarantee operators’ revenues and profits. 

To adequately support the development of mobile Internet and IoT, 5G must stimulate more breakthroughs in techno logies, especially network architecture and air interface technologies. 5G networks should also be more open in involving every role within the service process to engage in customizing services and networks. In order to meet these requirements, Huawei proposed the concepts of new air interface, architecture, and operation for 5G at MWC 2015. 

At their exhibition booth, Huawei demonstrated the physical and logical architectures of 5G networks with the use of a flash. This flash showed how the physical architecture is sliced to meet different service requirements as well as the dynamic changes in network elements (NEs) and functions involved in the slicing process. 

At the air interface technology exhibit, real application scenarios were simulated to demonstrating how air-interface waveform technologies and multiple access technologies are dynamically adjusted based on service requirements. The exhibit focused on three typical application scenarios in the foreseeable future: 3D calling (large bandwidth), driverless cars (low latency), and IoT (multiple connections). Not only were visitors able to experience each application scenario, but were also able to observe the waveform representations over the air interface as well as the multiple access technology. These representations allowed observers to immediately gra sp the concept of the 5G air interface technology and its ability to adapt to service requirements. 

At another exhibition booth in MWC 2015, Huawei showcased its next-generation operations support system Telco OS, an open operating system based on Internet architecture. For operators, the Telco OS represents the next-generation operating system able to integrate all assets (including those of subcontractors) as products or solutions for users. For developers, the Telco OS is the platform used for developing channels and customized services. For users, the Telco OS is a digital market space where they can participate in customizing their own required products or solutions. 

The wireless network architecture is a large organization, with each NE as a member of this organization. In the 4G network architecture, functions are strictly defined for each member. For example, a base station is responsible for transmitting and processing data, and the core network is responsible for forwarding data and controlling services. In the 4G era, service types for mobile Internet are simple, and each service process has been defined in the protocol. All NEs must work and cooperate effectively in the pre-defined way to ensure that the entire network is capable of efficiently completing tasks. In the 5G era, users and developers will participate in service customization. Therefore, in addition to the service types defined in the protocol, many new types of customized and personalized services will be developed. In this case, a fixed network architecture is too rigid to meet these diversified service requirements. 

Take the Internet of Vehicles (IoV) as an example. In a 4G network architecture, the base stations transmit information such as an autonomous vehicle’s status and the surrounding environment to the core network. The central controller then sends driving instructions to vehicles through the metropolitan area network (MAN) and transportation network. In this case, the end-to-end delay is longer than 1second and by the time vehicles receive their driving instructions, a traffic accident may have already occurred. 

To resolve this issue, 5G network architecture must be more flexible and allow NE functions to be defined based on actual service requirements, with service process control rights transferred to NEs at each layer. Again if we take the IoV example, in order to minimize the delay to a mere fraction for autonomous vehicles, base stations on a 5G network will consolidate data transmission, processing, and forwarding, as well as service control. This way, vehicle status and driving instructions are processed by base stations, and the delay will be shortened to under a 1 millisecond, allowing vehicles to promptly receive driving instructions and rapidly perform corresponding operations. 

However, function integration on base stations is not the ideal method. Several functions integrated on base stations occupy large portions of base station resources, and not all services require u ltrashort delay. For example, a smart sensor requires that collected data of its status be uploaded at specified intervals. This type of application does not have demanding requirements on the network bandwidth and for transmission delay. For this type of application, base stations only need to transmit and forward data to the central processor for processing. By doing this, the base station load is efficiently reduced allowing more smart sensors to connect to base stations, and idle resources to be allocated to other services. 

The 5G network architecture features are:

. Integration of connection management, mobility management, security management, and route management

. Service and user-centered design

. Support for mass applications in vertical industries

. Flexible and flattened organization

The role of each member in the organization is not fixed. Any member, even ordinary level employees, can be authorized to become the top leader based on service requirements. This organization ensures on-demand decision-making and eliminates top-down reporting and approval. It can also maximize the efficiency in processing various tasks, thereby allowing operators to transition from being pipe providers to being service providers. 

The pipe-to-service transformation principle also applies to the air interface. The air interface is the channel connecting terminals to the wireless network. On 4G networks, waveform and multiple access technologies are stereotyped among air interface technologies (OFDM, OFDMA, and half-duplex FDD/TDD). Therefore, the size of time-frequency resource blocks transmitted in a pipe and the number of users carried on each resource block are constant. The air interface acts like a highway, which allows only 4-meter-high and 2-meter-wide vehicles to pass with each vehicle carrying goods for a maximum of four different users. If a larger amount of goods need to be carried for a certain service, the goods must be sectioned in order to fit the vehicle’s size. Even if service blocks of some users are small, a vehicle can carry goods for a maximum of four users. Otherwise, goods for different users cannot be differentiated upon arriving at their destination. That is, each terminal cannot demodulate its required data. In addition, as the 4G system uses the half-duplex mode (FDD or TDD), 4G "highways" are unidirectional. In FDD mode, all vehicles on a highway must move in the same direction. And in TDD mode, all vehicles on a highway must move in the same direction and at the same time, thereby wasting resources. Therefore, the air interface technologies when in use can neither fully utilize spectrum resources nor adapt to different service requirements. 

In order to drive innovation in the mobile Internet experience and meet requirements of IoT development, the 5G system requires breakthroughs in air interface technologies which would successfully overcome restri ctions on the 4G air interface. At MWC 2015, Huawei presented the air interface technology set, including a new waveform technology Filtered-OFDM, a new multiple access technology SCMA, a new channel code Polar Code, and the full-duplex mode. These new technologies improve the spectral efficiency and adapt more flexibly to air-interface transmission requirements of different services. The Filtered-OFDM technology enables the air-interface waveform (or "highway") to be dynamically adjusted. If the size of users’ goods is large, large vehicles are used for transportation accordingly. The highway can be adjusted based on the vehicle height and width in order to maximize the traffic speed. The SCMA technology labels these goods with codes so that each vehicle can carry goods for up to six users. When goods arrive at the destination, users (terminals) can receive their own goods simply by identifying their own codes. Polar Code guarantees highway security and reliability during goods transportation. This way, goods carried by each vehicle can successfully arrive at their destination, thereby decreasing the bit error rate. In full-duplex mode, vehicles on a highway can move in different directions at the same time, thereby greatly improving the resource utilization efficiency. 

By comparison:

. 4G air-interface highway

All vehicles on a 4G air-interface highway must have the same height and width and move in the same direction at the same time. Each vehicle can carry goods for a maximum of four users. In addition, accidents may occur on the highway, thereby causing goods to be lost. In this case, the goods must be delivered again.

. 5G air-interface highway

Vehicles on a 4G air-interface highway can have different heights and widths and can move in different directions. Each vehicle can carry goods for up to six users. In addition, accidents rarely occur on the highway, thereby ensuring that goods are delivered to users in an efficient and timely manner. 

According to Huawei’s field test results, the application of 5G air interface technologies increases the radio spectral efficiency by more than 300% and better adapts to the requirements of different services on the time-frequency resource block size and transmission channel security.

With increasingly more attention being given to 5G, the requirements of every user and every industry are all being gradually defined. Huawei has been leading the industry in 5G R&D: 

. In 2012, Huawei developed the first 5G sample base station;

. In 2014, Huawei developed the first 100 Gbit/s sample base station;

. In 2015, Huawei is the first to give a clear descript ion of the 5G network architecture.

Huawei will make more investments in 5G R&D for new network architecture, new air interface technology, and new operation system to meet user requirements and support operator development. Huawei will also work closely with industry partners to unify global 5G standards and prepare for its eventual commercial use in 2020.

Huawei is participating in the Mobile World Congress 2015 in Barcelona, Spain. For more information, please visit: http://www.huawei.com/minisite/mwc2015/en/index.html