By Stephen Douglas, Head of Market Strategy, Spirent.
As 5G enters its refinement and expansion stage across much of the globe, the competition is already underway to reach the next frontier in telecommunications: 6G.
5G already accomplishes a great deal — offering reduced latency, simpler IoT device architectures, and the capacity to support up to a million tightly concentrated connections within small areas — yet these capabilities alone won’t be sufficient to deliver the futuristic IoT ecosystem we’re frequently promised is imminent.
Groundbreaking advances such as city-wide digital twins, holographic and immersive telepresence experiences, coordinated autonomous drone fleets, and seamless connectivity spanning land, air, sea, and space will all require 6G to become a reality.
Unfortunately, 5G remains constrained from reaching these possibilities by several stubborn technical limitations that 6G aims to address.
Latency
5G undeniably delivers a massive leap in latency performance compared to 4G. The best 4G could achieve was roughly 10 milliseconds of latency, though in everyday conditions that figure typically rose to somewhere between 30 and 50 milliseconds.
With 5G, one-way latency sits at approximately 1 millisecond, ranging from 10 to 20 milliseconds for everyday consumers, while dropping into the low single-digit milliseconds in private 5G and edge computing setups. Viewed broadly, the gap may appear modest — yet it is absolutely critical for the IoT applications that 5G was designed to enable.
This encompasses industrial robotics, which typically demand latency below two milliseconds so that the thousands of communications exchanged each second between robots and their controllers can be properly sequenced rather than queuing up.
The same requirement applies to live broadcast production, where camera feeds, audio signals, and remote camera controls all depend on consistently low latency — ensuring camera movements feel responsive and that live production workflows stay synchronised.
5G can technically support these applications but falls short of guaranteeing them reliably at scale over public networks. Regrettably, latency remains too elevated and too erratic even for those specific use cases.
The challenge facing many current 5G and IoT deployments isn’t solely that real-world latency remains excessive — it’s that the instability caused by jitter continues to pose a serious obstacle. Numerous factors degrade a 5G signal, including weather conditions, physical terrain, and electromagnetic interference.
These issues, in turn, amplify latency, inconsistency, and unpredictability between sending and receiving data. For many mission-critical next-generation IoT applications, this is simply unacceptable: the essential infrastructure systems, automated manufacturing facilities, and autonomous drone fleets that are waiting in the wings demand both lower latency and far greater dependability.
6G seeks to eliminate that unpredictability through an approach known as Deterministic Communications, engineered to foresee the exacting conditions that inflate latency and cause even slight interruptions.
To accomplish this, 6G will leverage Hyper-Reliable Low-Latency Communication (HRLLC), precise time synchronisation, and Time-Sensitive Networking (TSN) integration to provide dependable wireless connections, unified timing, and orchestrated traffic flows.
HRLLC supplies the low-latency, high-dependability link; time synchronisation ensures all network and application components remain coordinated; and TSN orchestrates critical traffic from end to end, enabling foreseeable latency, minimal jitter, and assured delivery. Collectively, these technologies will shift the network from a “best effort” model to deterministic communications — where latency, jitter, and packet delivery can be maintained within defined parameters for industrial, transportation, energy, and other mission-critical systems.
Device density
That leads us to another essential requirement that 5G currently cannot fulfil. 5G can accommodate roughly one million devices per square kilometre — once again a significant leap beyond 4G that unlocks new applications. Nevertheless, 6G aims to support as many as 10 million devices within that same footprint — and it is this potential for vastly greater connection density that will prove pivotal in crossing the technological threshold.
This is particularly relevant for smart cities — the vast, sensor-laden hubs of IoT devices woven into urban infrastructure that will transform the traditionally disjointed management of a metropolis into a fully integrated, automated network and real-time digital replica. Waste collection, energy distribution, public safety, environmental monitoring, traffic coordination, and far more will all be orchestrated through 6G-enabled massive IoT deployments, harnessing ambient IoT, integrated sensing, and AI-native networking.
5G can carry us part of the way toward that vision, but not all the way. The sheer volume of resources demanded and the complexity involved in its most sophisticated IoT applications — along with the intense communication between sensors, devices, and base stations — exceeds what 5G can sustainably manage.
6G, on the other hand, will rise to that challenge by pairing higher-capacity radio technology with more intelligent, energy-efficient network management.
It will employ strategies such as tapping into new spectrum bands with broader bandwidths and higher frequencies to accommodate more simultaneous connections, sophisticated massive MIMO antenna systems to direct signals with greater precision and reuse radio resources more effectively, AI-powered resource management to dynamically distribute capacity across millions of devices according to traffic type, priority, mobility patterns, and energy requirements, and streamlined IoT signalling to link enormous quantities of sensors, machines, tags, and devices within the same area without overburdening the network.
However, none of this is guaranteed, and 6G’s pledges — together with the applications it is intended to enable — hinge on the practical delivery of these technologies. Many organisations are already investing in 6G, and considerable iteration, advancement, and testing still lie ahead. 6G technologies are deeply intricate and will face pressures unlike anything encountered in the current generation of telecommunications.
We are navigating a demanding, multi-year research and development journey. Building prototypes and rigorously testing these emerging technologies must be a top priority for those seeking to gain an early competitive edge.
Simulating the future conditions of 6G networks will present significant challenges. This encompasses the energy demands, extreme throughput requirements, and the functional complexity involved — such as guaranteeing deterministic latency across geographically complex regions or maintaining enormous connection densities in high-frequency radio environments. 5G may represent a dramatic step forward from 4G, but for those determined to bring the IoT world of tomorrow into existence, the prototyping and testing of 6G technologies is already well underway.
Author biography:
Stephen Douglas leads Spirent’s Market Strategy team, where he steers the company’s long-term direction, pinpoints future growth avenues, and strengthens its competitive standing in the market. He also drives Spirent’s strategic programmes for 5G-Advanced, AI, and 6G networks, while serving as an independent advisor to multiple industry and government boards.
With nearly three decades of experience in the telecommunications sector, Stephen has remained at the forefront of next-generation technologies and has collaborated across the industry with service providers, network equipment manufacturers, and start-ups, helping them innovate, evolve, and shape the future of connected networks.
