In telecommunications, 5G is the fifth generation technology standard for broadband cellular networks, which cellular phone companies began deploying worldwide in 2019, and is the planned successor to the 4G networks which provide connectivity to most current cellphones.[2] 5G networks are predicted to have more than 1.7 billion subscribers worldwide by 2025, according to the GSM Association.[3] Like its predecessors, 5G networks are cellular networks, in which the service area is divided into small geographical areas called cells. All 5G wireless devices in a cell are connected to the Internet and telephone network by radio waves through a local antenna in the cell. The main advantage of the new networks is that they will have greater bandwidth, giving higher download speeds,[2] eventually up to 10 gigabits per second (Gbit/s).[4] Due to the increased bandwidth, it is expected the networks will increasingly be used as general internet service providers for laptops and desktop computers, competing with existing ISPs such as cable internet, and also will make possible new applications in internet of things (IoT) and machine to machine areas. 4G cellphones are not able to use the new networks, which require 5G enabled wireless devices.
The increased speed is achieved partly by using additional higher-frequency radio waves in addition to the low and medium band frequencies used in previous cellular networks.[2] However, higher-frequency radio waves have a shorter useful physical range, requiring smaller geographic cells. For wide service, 5G networks operate on up to three frequency bands – low, medium, and high.[5][2] A 5G network will be composed of networks consisting of up to three different types of cells, each requiring specific antenna designs as well as providing a different tradeoff of download speed to distance and service area. 5G cellphones and wireless devices connect to the network through the highest speed antenna within range at their location:
Low-band 5G uses a similar frequency range to 4G cellphones, 600–850 MHz, giving download speeds a little higher than 4G: 30–250 megabits per second (Mbit/s).[5] Low-band cell towers have a range and coverage area similar to 4G towers. Mid-band 5G uses microwaves of 2.5–3.7 GHz, allowing speeds of 100–900 Mbit/s, with each cell tower providing service up to several kilometers in radius. This level of service is the most widely deployed, and was deployed in many metropolitan areas in 2020. Some regions are not implementing low-band, making this the minimum service level. High-band 5G uses frequencies of 25–39 GHz, near the bottom of the millimeter wave band, although higher frequencies may be used in the future. It often achieves download speeds in the gigabit per second (Gbit/s) range, comparable to cable internet. However, millimeter waves (mmWave or mmW) have a more limited range, requiring many small cells.[6] They can be impeded or blocked by materials in walls or windows.[7] Due to their higher cost, plans are to deploy these cells only in dense urban environments and areas where crowds of people congregate such as sports stadiums and convention centers. The above speeds are those achieved in actual tests in 2020, and speeds are expected to increase during rollout.[5]
The industry consortium setting standards for 5G is the 3rd Generation Partnership Project (3GPP).[2] It defines any system using 5G NR (5G New Radio) software as "5G", a definition that came into general use by late 2018. Minimum standards are set by the International Telecommunications Union (ITU). Previously, some reserved the term 5G for systems that deliver download speeds of 20 Gbit/s as specified in the ITU's IMT-2020 document.
Overview
5G networks are digital cellular networks, for which the service area is divided into small geographical cells. The 5G wireless devices in a cell communicate by radio waves with a local antenna array and low power automated transceiver (transmitter and receiver) in the cell, over frequency channels assigned by the transceiver from a pool of frequencies that are reused in other cells. The local antennas are connected to transmission electronics connected to switching centers in the telephone network and routers for Internet access by high-bandwidth optical fiber or wireless backhaul connections. As in other cell networks, a mobile device moving from one cell to another is automatically handed off seamlessly to the current cell. 5G can support up to a million devices per square kilometer, while 4G supports only one tenth of that capacity.[8][9] The new 5G wireless devices also have 4G LTE capability, as the new networks use 4G for initially establishing the connection with the cell, as well as in locations where 5G access is not available.[10]
Several network operators use millimeter waves for additional capacity, as well as higher throughput.[11] Millimeter waves have a shorter range than microwaves, therefore the cells are limited to a smaller size. Millimeter waves also have more trouble passing through building walls.[12] Millimeter wave antennas are smaller than the large antennas used in previous cellular networks. Some are only a few centimeters long.
Massive MIMO (multiple-input multiple-output) was deployed in 4G as early as 2016 and typically used 32 to 128 small antennas at each cell. In the right frequencies and configuration, it can increase performance from 4 to 10 times.[13] Multiple bitstreams of data are transmitted simultaneously. In a technique called beamforming, the base station computer will continuously calculate the best route for radio waves to reach each wireless device and will organize multiple antennas to work together as phased arrays to create beams of millimeter waves to reach the device.[12][4]
Application areas
The ITU-R has defined three main application areas for the enhanced capabilities of 5G. They are Enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), and Massive Machine Type Communications (mMTC).[14] Only eMBB is deployed in 2020; URLLC and mMTC are several years away in most locations.[15]
Enhanced Mobile Broadband (eMBB) uses 5G as a progression from 4G LTE mobile broadband services, with faster connections, higher throughput, and more capacity. This will benefit areas of higher traffic such as stadiums, cities, and concert venues.[16]
Ultra-Reliable Low-Latency Communications (URLLC) refer to using the network for mission critical applications that require uninterrupted and robust data exchange.
Massive Machine-Type Communications (mMTC) would be used to connect to a large number of devices. 5G technology will connect some of the 50 billion connected IoT devices.[17] Most will use the less expensive Wi-Fi. Drones, transmitting via 4G or 5G, will aid in disaster recovery efforts, providing real-time data for emergency responders.[17]
Most cars will have a 4G or 5G cellular connection for many services. Autonomous cars do not require 5G, as they have to be able to operate where they do not have a network connection.[18]
However, most autonomous vehicles also feature teleoperations for mission accomplishment, and these greatly benefit from 5G technology.[19][20] While remote surgeries have been performed over 5G, most remote surgery will be performed in facilities with a fiber connection, usually faster and more reliable than any wireless connection.
Performance
5G speeds will range from ~50 Mbit/s to over a gigabit/s.[21] The fastest 5G is known as mmWave. As of July 3, 2019, mmWave had a top speed of 1.8 Gbit/s[22] on AT&T's 5G network.
Sub-6 GHz 5G (mid-band 5G), by far the most common, will usually deliver between 100 and 400 Mbit/s, but will have a much farther reach than mmWave, especially outdoors.[22]
Low-band spectrum offers the greatest range, thereby a greater coverage area for a given site, but is slower than the others.
5G NR (New Radio) speed in sub-6 GHz bands can be slightly higher than the 4G with a similar amount of spectrum and antennas,[23][24] although some 3GPP 5G networks will be slower than some advanced 4G networks, such as T-Mobile's LTE/LAA network, which achieves 500+ Mbit/s in Manhattan[25] and Chicago.[26] The 5G specification allows LAA (License Assisted Access) as well, but LAA in 5G has not yet been demonstrated. Adding LAA to an existing 4G configuration can add hundreds of megabits per second to the speed, but this is an extension of 4G, not a new part of the 5G standard.[25]
The similarity in terms of throughput between 4G and 5G in the existing bands is because 4G already approaches the Shannon limit on data communication rates. 5G speeds in the less common millimeter wave spectrum, with its much more abundant bandwidth and shorter range, and hence greater frequency reusability, can be substantially higher.[27]
Latency
In 5G, the "air latency"[28] in equipment shipping in 2019 is 8–12 milliseconds.[29] The latency to the server must be added to the "air latency" for most comparisons. Verizon reports the latency on its 5G early deployment is 30 ms:[30] Edge Servers close to the towers can reduce latency to 10–20 ms; 1–4 ms will be extremely rare for years outside the lab. The 5G latency KPIs (key performance indicators) are standardized by 3GPP in TR 28554
Error Rate
5G uses an adaptive signal coding system to keep the bit error rate low. If the error rate is too high the transmitter will switch to a less error prone coding mechanism. This sacrifices bandwidth to ensure a low error rate.
Range
The range of 5G depends on many factors. A key factor is the frequency being used. mmWave signals tend to have a range of only a couple of hundred metres whilst low band signals can, in the right circumstances, have a theoretical range of a couple of hundred kilometers.
