LTE CAT1 to CAT10, CAT0 and the Internet of Things

Cat. That is ue-category, according to the definition of 3GPP, ue-category is divided into 1~10 a total of 10 levels, of which cat.1-5 is R8 definition, cat.6-8 is R10 definition, cat.9-10 is R11 definition.

As shown above, ue-category mainly defines the upper and lower line rates that the UE terminal can support.

The cat.0 is an LTE terminal grade that is written to the 3GPP rel.12 Standard and supports a lower-rate, lower-power version. cat.0 and Cat.1 are all pointing to the vast IoT market, enabling lower power, lower cost IoT devices to connect to LTE networks. Supporting a lower category is critical for IoT applications such as wearables, smart homes, and smart meters.

However, there has always been a difficult gap between LTE and the Internet of things, whether it is the network or the end-chip, but with the active input of some communications equipment companies and chip companies over the years, it is expected to change the market situation and provide a broader perspective for the internet of things in LTE. For example, shortly before, Sequans and Altair announced the launch of the cat.0 and Cat.1 chipsets in the near future.

Why do you define cat.0?

In order to deal with the internet of things, lte-m must optimize the LTE network in several ways:

1) Equipment cost

The cost of connecting devices is a big problem, despite the enormous value of large amounts of device access. Devices that connect to a cellular network require chip support, and in order to support HD video and online gaming, LTE chips currently support dozens of to hundreds of MPBS high-speed, high-performance LTE networks. The higher the chip support rate, the more complex the hardware and the higher the cost. IoT applications do not need to be at this high rate, and even some devices require only hundreds of bps to connect to each other. Therefore, in order to reduce the cost of equipment, we have to simplify the chip to meet the needs of Internet of things applications.

2) Battery life

We can charge a cell phone or tablet every day, and IoT devices can't charge it every day or even every month, and it's not only inconvenient, but maintenance costs are rising. Some devices need to remain in operation for a long period of time, and once the battery runs out, the communication is interrupted and can lead to significant losses. For example, equipment used for fire alarm linkage directly transmits the signal to the fire center. Extra-long battery life is especially important.

3) Enhanced Coverage

For Internet of things applications, coverage is also very important. A simple example of a smart water meter is installed in a basement or in a hidden place in a building. These local signals are usually weak due to signal attenuation. Therefore, it is necessary to enhance the network coverage to deal with the internet of things.

Equipment Cost

In order to reduce the cost of equipment, R12 set the cat.0 terminal level, in fact, cat.0 refers to low-cost equipment. In order to reduce equipment complexity and reduce equipment costs, cat.0 defines a number of simplified solutions, mainly including:

1. Half-duplex FDD mode (half duplex FDD).

The half-duplex FDD mode allows time-division multiplexing in FDD mode.

2. Reduce the device receive bandwidth to 1.4MHz, of course, can also be extended to 20MHz.

3. Single receive path, cancel RX Diversity dual channel.

4. Low-speed data rate. Not only reduces the rate requirements, but also reduces processor computing power and storage capacity.

Further optimizations are also available in the R13 version, such as canceling the transmit diversity, supporting MIMO, supporting less than 1.4MHz of bandwidth, and supporting a lower data rate.

The features of the cat.0, Cat.1, Cat.4, and R13 versions of Cat are compared as follows:

In order to reduce the cost of equipment for the internet of things, it is necessary to optimize the battery length and coverage in addition to defining the cat.0 terminal Equipment class.

Battery service life

In order to save power, R12 uses a scheme called Power saving mode (PSM, power saving). If the device supports PSM, the PSM applies an activation timer value to the network during attachment or tau (Tracking area Update). When the device transitions from the connection state to the idle state, the timer starts to run. When the timer terminates, the device enters power-saving mode. When the device goes into power-down mode, the device no longer receives a paging message, and it appears that the device and network are missing, but the device is still registered in the network. The device will maintain this power-saving mode until the device needs to proactively send information to the network (such as periodic tau, sending upstream data, etc.).