Overview of 5G Basic Content
Mobile communication development history
-Mobile communication technology has the law of intergenerational evolution
-"G" stands for generation
-One cycle every ten years
5G and 4G reference value difference
| Indicator name |
Flow density |
Connection density |
Time delay |
Mobility |
efficiency |
User experience speed |
Spectral efficiency |
Peak velocity |
| 4G reference value |
0.1Tbps / km² |
100,000/km² |
10ms |
350km/h |
1 times |
10Mbps |
1 times |
1Gbps |
| 5G reference value |
10Tbps/km² |
1 million/km² |
1ms |
500km/h |
100 times improvement (network side) |
0.1-1Gbps |
3 times improvement (5 times in some scenes) |
20Gbps |
5G application scenario-VR/AR
-VR: virtual reality
-AR: Augmented reality
-MR: Mixed reality
-Internet of Vehicles
-Telemedicine: remote B-ultrasound remote surgery
-Smart city (sensing integration, collaborative innovation): transportation, medical care, construction public utilities, education and technology, public safety, and citizen services. Business-driven construction
-Smart City: Anyone can get the services they need at any time and anywhere.
-Adjust and monitor the entire process through operations and operations
Key 5G technologies: ultra-density networking
-Apply in scenarios that need to meet hotspots and high capacity (high traffic density and high rate)
-By massively increasing small base stations, trading space for performance
-Base stations generally include macro base stations and small base stations
-Macro base station: half of the coverage of "Tower Station" is several kilometers
-Small base station: half of the coverage area is 10m-200m
-Small base station advantages:
-Small size, low cost, easy to install, suitable for deep coverage
-Small interference, frequency reuse in a smaller range, increase capacity
-Close to users, improve signal quality and efficiency
Key technologies for ultra-dense networking
(1) Multi-connection technology
For macro-micro heterogeneous networking, micro base stations are mostly deployed locally in hotspots, and there are discontinuous coverage holes between micro base stations or micro base station clusters. Therefore, for the macro base station, in addition to implementing the control plane function of the signaling base station, it is also necessary to provide the user plane data bearer in the undeployed area of the micro base station according to actual deployment needs. The main purpose of the multi-connection technology is to realize the simultaneous connection between the UE (user terminal) and multiple wireless network nodes of macro and micro. Different network nodes may use the same wireless access technology, or may use different wireless access technologies. Because the macro base station is not responsible for the user plane processing of the micro base station, there is no need to achieve strict synchronization between the macro and micro cells, which reduces the performance requirements for the backhaul link between the macro and micro cells. In the dual-connection mode, the macro base station serves as the main base station in the dual-connection mode and provides a centralized and unified control plane; the micro base station serves as the dual-connection secondary base station and only provides the user plane data bearer. The secondary base station does not provide a control plane connection with the UE, only the RRC (Radio Resource Control) entity corresponding to the UE exists in the primary base station. After the primary base station and the secondary base station negotiate the RRM (Radio Resource Management) function, the secondary base station will pass some configuration information to the primary base station through the X2 interface, and finally RRC messages are only sent to the UE through the primary base station. The RRC entity of the UE can only see all messages sent from one RRU (Radio Frequency Unit) entity, and the UE can only respond to this RRC entity. In addition to being distributed in micro base stations, the user plane also exists in macro base stations. Since the macro base station also provides the function of the data base station, it can solve the problem of service transmission in the discontinuous coverage area of the micro base station.
(2) Wireless backhaul technology The existing wireless backhaul technology mainly works in the line-of-sight propagation environment, mainly working in the microwave frequency band and millimeter wave frequency band, and the propagation rate can reach 10 Gbit/s. The current wireless backhaul technology and the existing wireless air interface access technology use different technical methods and resources. In the existing network architecture, it is difficult to achieve fast, efficient, and low-latency horizontal communication between the base station and the base station. The base station cannot realize the ideal plug-and-play, and the deployment and maintenance costs are high. The reason is that it is restricted by the conditions of the base station itself, and the underlying backhaul network does not support this function. In order to improve the flexibility of node deployment and reduce deployment costs, wireless backhaul transmission using the same spectrum and technology as the access link can solve this problem. In the wireless backhaul mode, wireless resources not only serve the terminal, but also provide relay services for the nodes.
Ultra-dense networking planning and deployment
5G ultra-dense networking can be divided into two modes: macro base station + micro base station and micro base station + micro base station. The two modes implement interference and resource scheduling in different ways.
Macro base station + micro base station deployment mode 5G ultra-dense networking In this mode, at the service level, the macro base station is responsible for the transmission of low-speed and high-mobility services, and the micro base station mainly carries high-bandwidth services. The above functions are realized by the macro base station responsible for the coverage and the coordinated management of resources between the micro base stations, and the micro base station is responsible for the capacity, so that the access network can flexibly deploy the micro base stations according to the business development needs and distribution characteristics, so as to realize the control and control in the macro base station + micro base station mode. Separation of bearers. Through the separation of control and bearer, 5G ultra-dense networking can achieve separate optimization design of coverage and capacity, solve the problem of frequent handovers in dense networking environments, improve user experience, and improve resource utilization.
Micro base station + micro base station deployment model 5G ultra-dense network micro base station + micro base station mode does not introduce the macro base station as a network unit, in order to be able to achieve similar macro base station + micro base station mode in the micro base station + micro base station coverage mode The resource coordination function of the station requires a dense network composed of micro base stations to construct a virtual macro cell. The construction of a virtual macro cell requires multiple micro base stations in the cluster to share some resources (including signals, channels, carriers, etc.). At this time, the micro base stations in the same cluster perform transmission carried by the control plane on the same resource to achieve The purpose of the virtual macro cell. At the same time, each micro base station independently transmits user plane data on its remaining resources, thereby realizing the separation of the control plane and the data plane in the 5G ultra-dense networking scenario. When the network load is low, the micro base stations are managed in clusters, and the micro base stations in the same cluster form a virtual macro base station to send the same data. In this case, the terminal can obtain receive diversity gain, which improves the received signal quality. When the network load is high, each micro base station is an independent cell, sending its own data information, realizing cell splitting, thereby improving network capacity.
5G key technology : large-scale antenna array
- In order to more effectively tap the spatial freedom, more effectively use the energy of the transmitter, and find more diversity and multiplexing gains, modern communications generally use multiple antenna systems to improve the performance of the physical layer link, which we call multiple input multiple output technology (MIMO) .
Since the 1980s, MIMO has been widely used in IEEE 802.11 and 3GPP 4G LTE/5G NR systems. The MIMO method in the 802.11ac protocol can support up to 8 transmit and receive antennas (8x8 MIMO), while LTE R10/R13/R14 supports 8/16/32 base station-side transmit antennas to build a MIMO system.
Massive MIMO is a natural extension of MIMO technology. By increasing the number of original transmitting-side antennas by an order of magnitude (64 or 128), the above-mentioned gain is further improved at the same time;
In addition to providing more spatial freedom than MIMO, massive MIMO will also bring other advantages as the number of antennas increases .
Dynamic self-organizing network (SON)
SON (Self-Organizing Network, self-organizing network) is a complete set of network concepts and specifications derived from the development of LTE . SON is mainly proposed by operators, and its main idea is to realize some autonomous functions of wireless networks , reduce manual participation, and reduce operating costs .
Used to meet low-latency and high-reliability scenarios
Advantages:-Flexible deployment
-Support multi-hop
-High reliability
-Support ultra-high bandwidth
Software Defined Network (SDN)
Software Defined Network (SDN) is a new innovative network architecture proposed by the clean-slate research group of Stanford University, and it is a way to realize network virtualization. Its core technology, OpenFlow, separates the control plane and data plane of network equipment, thereby realizing flexible control of network traffic, making the network more intelligent as a pipeline, and providing a good platform for core network and application innovation . SDN technology can effectively reduce equipment load, assist network operators in better control of infrastructure, and reduce overall operating costs. It has become one of the most promising network technologies .
-Physically separate control plane and forwarding plane
-The controller centrally manages multiple forwarding devices
-Server and program are deployed on the controller
Network Function Virtualization (NFV)
NFV stands for Network Functions Virtualization, which is to deploy traditional CT services on a cloud platform (a cloud platform refers to a virtual machine platform formed by virtualizing physical hardware, which can carry CT and IT applications) to achieve Decoupling of software and hardware.
-Software and hardware decoupling, virtualization
-Realize network function through hardware
The difference between NFV and SDN
NFV is oriented to the device form, decoupling hardware and software, freeing the network L2~L7 layer functions (firewalls, switches, etc.) from proprietary hardware, allowing it to be used in general virtual devices (vm/container/microkernel) Wait and run. What is achieved is the pooling of network resources.
SDN is oriented to the network architecture and separates control and forwarding, enabling flexible deployment, management, monitoring and scheduling of network layer L2 to L7 functions, and flexible scheduling of traffic. That is to say, the management and scheduling of network resources are realized.
Challenges facing 5G-spectrum resources
The frequency band below 5GHz is already very crowded
-Solution direction: high frequency and ultra high frequency
New scene challenge
-Mobile hotspots: ultra-density networking challenges brought by a large number of hotspots
-Internet of Things: The new business of the Internet of Things far exceeds the scope of human activities
-Low and high altitude coverage: drones, aircraft route coverage, etc.
New business/security challenge
-uRLLC: Refers to businesses such as unmanned driving and industrial automation, which have high requirements for delay and reliability.
Low-latency security algorithms, edge computing, privacy protection
-mMTC: Refers to large-scale Internet of Things business, which has high requirements on the number of connections, power consumption/standby
Lightweight and safe, massive connection signaling storm
-eMBB: Refers to high-traffic mobile broadband services such as 3D/Ultra HD video, AR/VR, and requires high transmission rates.
Security processing performance, secondary authentication, known vulnerabilities
New architecture challenges
-SDN, NFV and other new security challenges
Terminal equipment challenge
-Explosive growth of IoT terminals
-Terminal multi-mode R&D, process, battery life and other challenges.
In short, 5G technology can increase the existing bandwidth, enhance model stability, and lay the foundation for the budding of various new industries. At the same time, challenges coexist with opportunities and need to be continuously optimized for different application scenarios.