Leti Completes LPWA Field Trials of New Waveform for 5G IoT Networks

Leti recently completed field trials of its IoT tailored LPWA technology. Termed the LPWA-CB trials, the results have shown significant performance gains in coverage, data-rate flexibility and power consumption compared to leading LPWA technologies.

Leti’s LPWA includes its patented flexible approach to the physical layer, Turbo-FSK waveform. It also relies on channel bonding, the ability to aggregate non-contiguous communication channels to increase coverage and data rates. The field trials confirmed the benefits of Leti’s LPWA approach in comparison to LoRa and NB-IoT, two leading LPWA technologies that enable wide-area communications at low cost and long battery life.

The new technology is especially suitable for long-range massive machine-type communication (mMTC) systems. These systems are expected to proliferate after 5G networks are deployed, beginning in 2020. Cellular systems designed for humans do not adequately transmit the very short data packets that define mMTC systems. Designed to demonstrate the performance and flexibility of the new waveform, the field-trial results stem primarily from the system’s flexible approach of the physical layer. The flexibility allows data-rate scaling from 3Mbit/s down to 4kbit/s, when transmission conditions are not particularly favorable and/or a long transmission range is required.

Under favorable transmission conditions, ex. a shorter range and line of sight, the Leti system can select high data rates using widely deployed single-carrier frequency-division multiplexing (SC-FDM) physical layers to take advantage of the low power consumption of the transmission mode. Under more severe transmission conditions, the system switches to more resilient high-performance orthogonal frequency division multiplexing (OFDM).

When both very long-range transmission and power efficiency are required, the system selects Turbo-FSK, which combines an orthogonal modulation with a parallel concatenation of convolutional codes and makes the waveform suitable to turbo processing. The selection is made automatically via a medium access control (MAC) approach optimized for IoT applications.

In the new system, the MAC layer exploits the advantages of the different waveforms and is designed to self-adapt to context, i.e. the usage scenario and application. It optimally selects the most appropriate configuration according to the application requirements, such as device mobility, high data rate, energy efficiency or when the network becomes crowded, and is coupled with a decision module that adapts the communication depending on the radio environment. The optimization of the application transmission requirements is realized by the dynamic adaptation of the MAC protocol, and the decision module controls link quality.

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