Besides High Speeds, What Else Will 5G Bring Us?

The Core Technologies of 5G

Enhanced Mobile Broadband (eMMB)

Channel Coding Technology

NOMA Technology

Millimeter Wave

Massive MIMO and Beamforming

Cognitive Radio

Ultra-Reliable and Low Latency Communications (URLLC)

5GNR Frame Structure

Multi-carrier Technology Improvement

Network Slicing

Massive Machine Type Communications (mMTC)

5G Networks and Coverage

Spectrum Allocation in China

  • Mature industrial chain, complete research and development, and the greatest global practicability;
  • Fast development pace, and early commercialization;
  • Lower frequency, higher cost-effectiveness, lower base station density, and less capital expenditure.
  • The 100 M bandwidth at the 4.9 GHz band can support more users and larger traffic, but requires more base stations, which places pressure on capital expenditure;
  • The industrial chain of the 2.6 GHz spectrum is less mature, so China Mobile needs to actively cultivate and deploy it. However, this spectrum provides wide coverage at a lower cost, which gives a dual-band assurance to 5G commercial use.

Hotspot Coverage or Continuous Coverage?

SA or NSA?

Ultra-dense Network (UDN)

  1. Multi-connection technology, which is designed to implement simultaneous connection between UE and multiple macro and micro wireless network nodes. In dual-connection mode, a macro base station serves as a primary base station and provides a unified control plane, while a micro base station serves as a secondary base station and only bears data on the user plane. The secondary base station does not connect UEs to the control plane. The radio resource control (RRC) entity corresponding to the UE exists only in the primary base station.
  2. Wireless backhaul technology. In the current network architecture, it is difficult to achieve fast, efficient and low-latency communication between base stations, and base stations have not yet reached the ideal state of plug-and-play. To make node deployment more flexible and ensure lower deployment costs, we may resort to wireless backhaul transmission by using the same spectrum and technology as the access link. In wireless backhaul, wireless resources serve UEs while providing relay services to nodes.
  3. Dynamic adjustment of small cells to maximize spectrum utilization. Occasional events such as exhibitions and football games may cause obvious traffic fluctuation and surging online sharing, which requires a large uplink capacity. For indoor venues, uplink/downlink (UL/DL) subframe ratio needs to be dynamically adjusted based on real-time traffic. For example, uplink-dominated configuration can be used to meet uplink video transmission requirements. In scenarios with high demand for downlink resources, such as movie and music downloads, a downlink resource proportion needs to be increased for transmission, for example, adjusting the D/U ratio from 3:1 to 8:1. In scenarios with high demand for uplink resources such as live broadcasts and video or audio content upload, the D/U ratio can be adjusted from 3:1 to 1:3. In addition, user groups under similar service types usually cluster, or even occupy entire cells. Therefore, in a deployment area, if user service demand for a period of time shows a stable and obvious feature, such as high demand for uplink services, uniform timeslot adjustment is required for the cells in the area.

Summary

  1. The target peak rate of a single base station is 20 Gbps, and the target spectral efficiency is 3 to 5 times that of 4G. These are indicators of application in eMBB scenarios. The following technologies are primarily involved in this part: LDPC code and Polar code, used to increase capacity; the millimeter wave, used to expand spectrum resources; NOMA, used to achieve PDMA power domain gain; and Massive MIMO, used to increase capacity. By virtue of the shorter wavelength, millimeter wave allows shorter antennas to be used, so that a mobile phone can accommodate more antennas and a base station can support a total 64T64R array of 128 antennas.
  2. Latency is reduced to 1 ms. This is related to the URLLC scenarios. The new air interface standard 5GNR defines a more flexible frame structure, which allows for a more flexible subcarrier spacing configuration. The maximum subcarrier spacing of 240 kHz corresponds to a timeslot of 0.0625 ms, making ultra-low latency applications possible. New multi-carrier technologies are used to reduce resource waste, such as the guard interval in the CP-OFDM system, therefore reducing latency and increasing utilization. In addition, network slicing technology can make networks more flexible, better support ultra-low latency applications, and establish an end-to-end high-speed channel. Network slicing technology is mainly applied to the SDN and network function virtualization (NFV) of core networks.
  3. The connection density reaches 1 million per square kilometer. This is related to the mMTC scenarios. At present, 5G standards are mainly based on eMTC and NB-IoT, both of which have their own advantages and disadvantages. eMTC is a better choice for services with high demand on traffic, mobility, and latency. NB-IoT is more suitable in scenarios that feature stationary devices and low data traffic, and have low requirements for latency but high requirements for working hours, facility costs, and network coverage. Currently, NB-IoT coverage is dominant in China. The connection density mentioned here is actually an ideal value subject to change, because the increase in connection density is highly dependent on the UE dormancy implemented by the PSM and eDRX technologies. More concurrency capabilities, lower network signaling consumption, more burst data packets, and other scenarios must be taken into account in the future. The development of connection density still has a long way to go.

Afterword

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