Low Power Wide Area (LPWA) technologies are a subset of LTE designed for IoT applications that prioritize low hardware costs, ultra-long battery life, and global coverage. Most LPWA technologies are geared toward low-bandwidth applications such as asset trackers, pet trackers, utility meters, and agricultural sensors.
The exception is Cat 1 bis, which is designed for IoT applications that need faster uplink and downlink speeds. For example, the speeds and low latency of Cat 1 bis make it a good fit for video applications such as security cameras and telematics cameras that monitor driver behavior or cargo conditions.
Here’s how Cat 1 bis stacks up against the other LPWA technologies — LTE Cat M1 and LTE Narrowband-IoT (NB-IoT) — and with LTE Cat 1 and LTE Cat 4.
Lower Cost and Complexity, with No Coverage Tradeoffs
Cat 1 bis, Cat M1, and NB-IoT all are part of the LTE family of standards. This is a major plus because although most operators are currently building or expanding their 5G networks, LTE won’t disappear into the sunset anytime soon simply because their 4G networks have too many customers to orphan. (For more information about Cat M1 and NB-IoT, see “Choosing the Right LTE Standard for IoT Applications.”) This means developing new Cat 1 bis devices today is a sound business investment for applications whose market potential and service life extend through the end of this decade.
Another advantage is that Cat 1 bis devices have only one receive antenna rather than two for Cat 1. This reduces the complexity, cost, and size of Cat 1 bis devices because less PCB space is required and because their chipsets have only one RF input.
As an LPWA technology, Cat 1 bis supports extended Discontinuous Reception (eDRX), Power Saving Mode (PSM), and RRC Inactive (RAI). All three reduce power consumption and thus extend battery life.
One key difference is that mobile operators do not have to have to make any changes to their RAN or core network to support Cat 1 bis devices, unlike LTE-M. As a result, Cat 1 bis devices can connect to any LTE network — provided, of course, that they meet operator and regulator certification requirements and have a subscription. This is critical for devices that will travel around a country, continent, or the planet — such as shipping container trackers — because roaming is available. It’s also valuable for developing applications that can be sold in multiple countries and continents.
A key difference from NB-IoT is that Cat 1 bis is designed to support mobile applications, such as telematics. Cat 1 bis also supports Voice over LTE (VoLTE). This can be useful for applications such as in-cab telematics cameras that provide drivers with real-time feedback and coaching.
Operator Performance Requirements
Each mobile operator has a set of performance requirements — measured in total radiated power (TRP) and total isotropic sensitivity (TIS) — that LPWA devices must meet in order to use its network.
For example, AT&T requires Cat 1 bis devices to meet the primary TIS minimums for each band.
AT&T also is an example of how Cat 1 bis devices can be exempt from form factor requirements that apply to other LPWA technologies. For instance, if a Cat M1 device has a form factor under 107 mm in the longest direction, AT&T has a specific set of TIS and TRP requirements. (For more information, see “Choosing the Right LTE Standard for IoT Applications.”)
Finally, if a Cat 1 bis device uses an external antenna with a cable longer than 20 cm, then it’s also exempt from PTCRB certification requirements.
For a deeper dive, check out the “LTE Cat 1 bis Explained: The Future of IoT Connectivity” webinar, featuring Taoglas’ partners Sequans and Soracom. It’s available on demand and covers key aspects such as:
- How TRP and TIS relate to antenna efficiency.
- Best practices for antenna integration, including ground plane sizing, maintaining adequate keep-out areas, and impedance matching.
- Tips for mitigating noise to maximize performance.
- Domestic and global roaming considerations.
- How chipset enhancements can narrow the sensitivity difference between Cat 1 bis and LTE Cat 1 devices.
