Long Term Evolution (LTE) is the cellular standard, developed by the 3GPP standards partnership, that most mobile carriers use for their 4G networks. It is an all-packet data architecture: everything it carries travels as IP traffic, and voice runs over IP as VoLTE where the carrier and device support it. It replaced the older 3G systems as the main way phones, mobile routers and connected devices get data. Although 5G is now widely deployed, LTE still provides broad coverage, serves as the fallback layer under many 5G networks, and is common in business backup links and IoT devices.
At a glance
- LTE is the standard behind what carriers sell as 4G or 4G LTE; later releases, such as LTE-Advanced, raised speeds and capacity.
- It is an all-packet system with no circuit-switched voice of its own; voice uses VoLTE over IP where carrier and device support it, and some older deployments fall back to legacy networks for calls.
- Real-world speed and latency depend on the carrier, spectrum, signal, device and cell load, so test at the site.
- Businesses use it most as a failover link, for temporary or hard-to-wire sites, for mobile workers and for IoT.
- Device-focused versions, LTE-M and NB-IoT, serve low-power sensors and trackers.
What problem it solves
Wired internet doesn’t reach everywhere, takes time to install and occasionally fails. LTE gives a business a connection wherever a carrier has coverage, with no construction: a router with a SIM card can be online the day it arrives. That makes it useful as a backup when a branch’s fiber or cable link goes down, as a stopgap while a new site waits for wired service, and as the main connection for vehicles, kiosks, construction sites and remote equipment.
Before LTE, cellular data was too slow and inconsistent for most of these roles. LTE’s higher capacity and lower latency than 3G made cellular practical as a real business link, not just a phone service.
How it works
Radio access. Devices connect over licensed spectrum to carrier base stations, called eNodeBs. LTE uses OFDMA on the downlink and a related scheme, SC-FDMA, on the uplink, dividing spectrum into many small channels that the network schedules among users. Carriers run LTE across many frequency bands, so device compatibility with the carrier’s bands matters.
Core network. The Evolved Packet Core handles authentication using the SIM or eSIM, assigns IP addresses, manages mobility as devices move between cells and connects traffic to the internet or a private network. Because LTE has no circuit-switched domain, voice needs extra support. Where the carrier and device support it, calls run over IP as VoLTE through the carrier’s IMS call system; in older deployments, or with devices that lack VoLTE, phones may drop back to a legacy circuit-switched 2G or 3G network for calls, which stops working where those networks have been shut down.
Backhaul. Each cell site connects to the carrier’s core over fiber or microwave backhaul. Its capacity, along with how many users share the cell, shapes the performance you see.
Business access. A business typically uses LTE through a cellular router or a module built into an SD-WAN appliance or firewall, on a data plan from a carrier or MVNO. Options include public internet access, a static IP address, or a private network connection into the carrier’s core that keeps traffic off the internet. Organizations can also build their own private cellular networks on LTE or 5G, in the US often using CBRS spectrum.
IoT variants. LTE-M and NB-IoT are lower-power, lower-bandwidth versions of LTE for devices that send small amounts of data and need long battery life. They are one form of low-power wide-area network.
When it matters for buyers
- When you need branch backup. Cellular failover over LTE or 5G is a common way to keep a site online when its main circuit fails.
- When a site can’t wait for wired service. LTE can connect a new office, store or job site while fiber is ordered.
- When devices move or sit in odd places. Vehicles, kiosks, ATMs, digital signage and sensors often depend on LTE.
- When buying routers or IoT devices. Check supported bands and carriers, and whether the device can also use 5G, because equipment often outlasts carrier network plans.
- When signal indoors is weak. External antennas or a cellular signal booster may be needed before LTE is usable.
Many sites pair LTE with fixed wireless or wired services as primary or backup connectivity.
Questions to ask vendors
- What signal strength and speeds can we expect at each of our addresses, and can we test before committing?
- Which bands and carriers does the router or device support, and does it also support 5G?
- Is the plan unlimited, pooled or capped, and what happens when we exceed the allowance (throttling, overage or deprioritization)?
- Can we get a static IP or a private connection into your network for management and security?
- How is failover triggered and how quickly does traffic move back when the main link recovers?
- How long do you expect to support LTE on your network, and how will changes be communicated?
- For IoT: do you support LTE-M or NB-IoT where our devices are deployed, including roaming?
How it differs from 5G
LTE and 5G are successive generations of cellular standards from the same body. 5G adds new radio technology and new spectrum, including very high bands, and it is designed for higher capacity, lower latency and many more connected devices. Many 5G networks still rely on LTE: in “non-standalone” mode, 5G uses an LTE network for control and adds 5G radio for extra capacity. For a business backup link, the practical differences are coverage, speed at your site and price, which vary by carrier and location. Where 5G coverage is good, it often performs better; where it isn’t, devices fall back to LTE. Both are a form of wireless WAN when used to connect a site.