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Ask the Quexperts: What is LTE Cat 1 bis?

LTE Cat 1 bis is a variant of LTE that has been developed specifically to support IoT applications. Introduced within 3GPP Release 13, Cat 1 bis uses existing LTE networks but, critically, has been designed to operate with a single antenna, in contrast to LTE Cat 1 which requires that IoT devices have two antennas. This has obvious benefits in terms of enabling LTE Cat 1 bis devices to be more compact and simpler to design than LTE Cat 1 devices.

The bis name is not an acronym but instead a Latin word meaning ‘second time round’ which reflects the improvements Cat 1 bis brings in comparison to LTE Cat 1. An important benefit is that Cat 1 bis can offer the same data rate, latency, roaming capabilities and robustness as LTE Cat 1, even though it has a single antenna. In addition, Cat 1 bis uses the same infrastructure and standards as LTE Cat 1 so there is no need to rethink development approaches or introduce completely new technology.

In common with LTE Cat 1, Cat 1 bis offers 10Mbps downlink and 5Mbps uplink data rates, 20MHz bandwidth and latency of less than 100ms. These performance criteria set Cat 1 bis apart from other LTE variants that support single antenna designs including LTE Cat 0, LTE Cat M1 and LTE Cat NB1 (NB-IoT) which offer throughput of under 1Mbps.

LTE Cat 1 bis therefore provides an attractive performance sweet spot for IoT applications that need greater performance than the lower end LTE variants while achieving form factor benefits. However, Cat 1 bis hardware can be more expensive than LTE-M and NB-IoT devices so it is practical mainly for use cases that can take advantage of the higher data rate to outweigh the lower costs of LTE-M and NB-IoT.

What is LTE Cat 1 bis used for?

Typical Cat 1 bis applications include massive IoT deployments such as asset tracking, logistics, transport, telematics, sensor networks, smart cities, smart meters and micro-mobility applications. These relatively low-power, low-bandwidth use cases have greater need for speed than the most basic applications and can take advantage of Cat 1 bis to achieve reduced power consumption alongside minimized form factors and the simplicity of having a single antenna.

As the market matures, it is anticipated that the huge volumes of IoT devices that utilize Cat 1 bis will result in Cat 1 bis modem prices coming closer to the costs of LTE-M and NB-IoT modems, thereby strengthening the overall value proposition still further. In addition, innovation is ongoing. Features such as power saving mode (PSM) and extended discontinuous reception (eDRX) can also be used in Cat 1 bis devices, thereby minimizing power consumption and maximizing the active lifespan of devices.

In a nutshell, LTE Cat 1 bis provides an evolution from LTE Cat 1 that does not require dual antennas while delivering comparable performance, with reduced power consumption features and compactness as added benefits. If you are planning to draw on the advantages of LTE Cat 1 bis in your next IoT device project, click here to watch a short video on our offering, the EG800Q module.

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