5G Key Technologies
This article provides an overview of several of the most important new technologies developed for the 5G Networks. To meet the 5G design vision, service and performance requirements, new technologies were required; some are extensions of 4G and, some are developed explicitly for 5G.
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5G Design Use Cases
5G network performance and design goals are commonly described with three core targets.
- eMBB: High Data Rate: Enhanced mobile broadband enables ultra-high data-rate communications, enhanced mobility and broader network coverage. 5G networks have a similar performance and user experience as Ethernet networks.
- uRLLC: Low Latency, High Reliability: Ultra-Reliable Low-Latency Communications is critical for public safety, electronic health, medical automation, self-driving cars, and the “tactile” internet.
- mMTC: Internet of Things: Massive Machine-To-Machine Communications provides ubiquitous connectivity to an extremely large number of devices. These devices will require a high density of network connections, energy efficiency for extended battery life and reduced cost per network connection.
Key Performance Indicators (KPI)
Below is a chart of 5G performance target parameters.
| Indicator | Description | 5G target |
|---|---|---|
| Peak data rate | Maximum achievable data rate | 20 Gbit/s |
| Packet Latency | Radio network contribution to packet travel time | 1 ms |
| Reliability | Maximum packet loss | 00001 Pkt/s |
| Availability | Network uptime availability | 99.999% |
| Mobility | Maximum device speed crossing multiple cells performing device handoffs with no network disruptions or packet loss | 500 km/h |
| Coverage | Total network coverage in designated zones | Near 100% |
| Connection density | Total number of devices per unit area | 106/km2 |
| Energy efficiency | Energy consumption (by device or network) | 10% of 4G |
| Spectrum efficiency | Throughput per unit wireless bandwidth and per network cell | 4x 4G |
| Area traffic capacity | Total traffic across coverage area | 1000 (Mbit/s)/m2 |
| Security | Defined in specification 3GPP TS 23.501 |
Millimeter Wave Technology (mmWave)
5G specified radio frequencies are higher than frequencies used by 4G, which has advantages and challenges. Higher frequencies provide larger network bandwidth, lower latency and much higher connection density. Higher frequencies also have challenges with reduced transmission distances, requiring a larger number of smaller cells.
5G network frequency range begins at 5GHz. The 5G network frequencies are called Millimeter Wave Bandwidth (mmWave) and are 24GHz and above. 4G frequencies ranged from 700MHZ to 2.5GHz.
mmWave Advantages
- Higher network throughput, up to 20Gbps
- Reduced network latency and data transfer rates
- Large network connection capacity, supporting more devices and subscribers
- Reduced overhead cost which should reduce cost per network connection
- Larger frequency bandwidth range increases network throughput capacity
mmWave Disadvantages
- Higher frequency radio waves have reduced ranges of about 300 meters
- Smaller cell sizes, increased number of cell antennas
- Shallow obstruction penetration, clients need to be nearly line-of-sight
Full Duplex
Advances in signal processing electronics now support full-duplex network communications on the same frequency. Earlier technologies required different frequencies to transmit and receive data simultaneously.
Full duplex reduces radio frequency usage by half, doubling the number of devices that can be supported on cell towers.
5G Client Communications
The 5G protocol between 5G clients and 5G base stations must calculate or establish several details during the connection process. 4G and earlier protocol connection, security and session management remains the same and is not called out here. New requirements for 5G include,
- Transmission signal power requirements are calculated and the minimum amount of power is used to reduce client power output and extend battery life.
- The signal/noise ratios are monitored and the transmission power adjusted to maintain reliable connections
- Location positioning of the client device is identified when the session is established and is continuously updated for moving client devices.
- The client angle and distance are calculated at the 5G base station from the antenna array architecture and the 5G session protocols.
- The client geographical position can be calculated from the distance to the base station antenna and the angle off from perpendicular.
- Location-based technology
- The 5G calculated location position can be used for similar purposes as GPS systems but without the power requirements of GPS electronics.
- The speed and path of client devices in motion are monitored. 5G base station antennas must track client movements to direct radio beams directly at clients.
Infrastructure Based on NFV/VNF and SDN
One of the core architectural requirements specified for 5G infrastructures is that all core network systems are based on software virtualization. Network infrastructures have traditionally included physical purpose-built appliances, which are less flexible to manage, deploy and scale.
Network Functions Virtualization (NFV) is a network architecture based on Virtual Network Functions (VNF). Network functions include network routing, packet processing, security, and many others.
Software Defined Networks (SDNs) are a virtualization technology that abstracts physical networks to virtual network structures. Virtual networks appear and behave like physical networks but have similar advantages of other virtualization technologies.
5G Packet Core processing functional overview
The above diagram shows a simplified view of 5G core functions using NFV/SDN. The traffic management including services, orchestration, control and data packet management is implemented as a set of VNF chained services.
The physical network resources are presented with a virtual network overlay using SDN.
5G Carrier Network Advances
The 5G network specifications also include network technology advances in functionality, reliability and performance. These include:
- Flat and distributed network architectures
- SDN technologies provide the shortest path without traversing the carrier core network
- 4G was hierarchical – all data was routed through EPC core network
- For example, 5G client network traffic is routed:
- Direct to MEC/Cloud Edge servers
- Direct internet services
- SDN technologies provide the shortest path without traversing the carrier core network
- Multi-RAT internetworking (Multi-Radio Access Technology)
- Interoperability with other access networks: 3G, 4G, WiFi, Bluetooth
- Multiple access
- Multi-path transmission enables a device to use multiple protocols simultaneously
- Enhancing reliability and data transmission rates
- MPTCP (Multi-Path TCP), a device to open several TCP sessions simultaneously, uses multiple network TCP sessions
- Advantages
- Throughput, path capacity enhancements and channel error reduction
- Mobility improvement and latency reduction using improved path switching control
- Minimized HIT (Handover Interruption Time) using RTO (Retransmission Timeout) control and improved handover decisions
- Multi-path transmission enables a device to use multiple protocols simultaneously
- Context-aware resource allocation
- Considers real-time traffic
- Considers network service types
- Aware of device characteristics
- Content caching of popular content
- CDN (Content Delivery Network) services are deployed at the network edges
- Improves performance and user experience
- Reduced latency and traffic
Device-to-Device (D2D) Communications
Device-to-device communications is an emerging trend in “smart” systems and IoT devices that communicate and share data and knowledge, and then to potentially act on this knowledge. Fog computing, for example, is based on IoT devices communicating and sharing data.
- 5G clients can communicate directly with other 5G clients, bypassing the carrier networks
- This offloads traffic from the mobile networks and reduces cost
- Use cases include:
- V2X – Vehicle-to-vehicle communications
- Emergency signals between vehicles and RSUs (roadside units)
Network Slicing
Logical network slices create tenant or service-specific networks. The network slicing creates end-to-end isolated logical networks starting from the mobile edge, continuing through the RAN mobile transport through the 5G core. Tenants are service providers delivering specific services over the network. These tenants will have specific network requirements such as reliability, latency or bandwidth.
Service-specific networks will have key performance indicator (KPI) requirements to meet a specific business need.
Network Slicing example with four logical network slices
Network Slicing example with four logical network slices
In the diagram above, NFV and SDN technologies have been used to create four isolated and independent logical networks. The 5G network resources are “sliced.” Each network slice has different network performance specifications for different use case or business requirements.
Multi-Tenancy
Multi-tenancy uses network slicing and subscriber awareness to create isolated logical networks for independent service providers. Tenant networks can be defined with different performance characteristics and service levels.
Diagram of Multi-tenancy in Mobile Carrier Infrastructures
Diagram of Multi-tenancy in Mobile Carrier Infrastructures
In the above diagram, Tenant A has an isolated logical network provided by network slicing. Tenant A and B share a common physical network infrastructure.
Massive MIMO
Multiple Input Multiple Output (MIMO) is a technology that uses multiple antennas configured in a two-dimensional phased array. The MIMO antenna system is attached to a base station that controls the transmission and reception of radio signals.
Massive MIMO systems are larger MIMO systems with up to several hundred antennas.
Multiple antennas working together provide several advantages:
- Multiple parallel antennas have higher gain
- Resistant to intentional jamming
- More paths to the 5G client provide stronger signal strength
- Transmissions can be focused in a beam at 5G clients, which is called beamforming and provides more power to the client with less interference
- More parallel antennas can serve a larger number of users
- Antenna arrays can identify 5G client physical locations
- Arrays can also track mobile clients and direct the transmission beam at the client, following the client movements and maintaining network connectivity
Massive MIMO systems can handle large volumes of network throughput and support large numbers of client connections, which is a core performance requirement for 5G networks.
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References
5G-PPP View on 5G Architecture (Version 2.0) white paper: https://5g-ppp.eu/wp-content/uploads/2017/07/5G-PPP-5G-Architecture-White-Paper-2-Summer-2017_For-Public-Consultation.pdf
Fundamentals of 5G Mobile Networks – Wiley (2015)
3GPP TS 23.501 V15.4.0 (2018-12) – https://www.3gpp.org/DynaReport/23-series.htm