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7 December 2018

MulteFire adds Cat-M and Cat-NB to its LTE-U specification

The MulteFire Alliance has announced that is has added support for eMTC-U and NB-IoT-U to its Release 1.1 specification, bringing LTE Cat-M and Cat-NB capabilities to the somewhat controversial LTE-U space – which will let adopters run LTE services in the unlicensed spectrum bands, despite WiFi’s feats that LTE will end up abusing WiFi’s listen-before-talk behavior.

While the LTE community is pretty happy with being able to adapt its protocol to use these unlicensed bands, there are many rather vocal critics of this approach, who argue that LTE is going to interfere with many of the other users in these bands. The unlicensed ISM bands are crucial for many IoT applications, particularly in the 900MHz range and the 2.4GHz band, and so there are many that see LTE-U as a hostile incursion.

Nokia is on board, with Asimakis Kokkos, chair of MulteFire’s Technical Specification Group and the head of Industry Environment Strategy at Nokia, saying that “MulteFire 1.0- is a novel technology that was designed to create new wireless networks, but operating LTE-based technology standalone in unlicensed or shared spectrum bands. MulteFire 1.1 takes the potential of this technology even further, by improving on the performance of v1.0 for the global 5GHz unlicensed band, and by adding new capabilities for additional spectrum bands.”

These new additions include eMTC-U in 2.4GHz, NB-IoT-U in the 900MHz bands, and MulteFire 1.9GHz support, also called sXGP (for Band 39 operations, in support of the XGP Forum’s plans for TD-LTE devices in Japan). Enhancements were also made for MulteFire 1.0 Broadband Service, which run in the 5.8GHz band, for faster uplink speed, Wideband Coverage Enhancements (WCE) for faster downlink, SON (Self-Organizing Network) capabilities, and perhaps most interesting, Autonomous UE Mobility (AUM), which will support transport speeds of 50km/h for mobile services. There’s a whitepaper available here, which outlines these additions in more detail.

LTE-U could offer a way for companies to create private LTE networks, or simply to fill in gaps that an MNO has left in their networks. There has been a lot of interest from enterprises and industrial firms, but so far, not much in the way of commitments. Something like a factory complex would benefit from having a private network on which to run IoT applications, as would an office complex that wanted to improve indoor reception, but initially, it seems that private LTE networks will be limited to large players.

The use of the CBRS is comparable to MulteFire, but again, like most of the LTE-U discussions, it is being pitched as a way to solve the WiFi problem – that is, high-bandwidth (and thus valuable) communication being offloaded onto networks that the MNOs can’t monetize.

These MNOs are worried that there will come a time when consumers can get by with just WiFi, or at least with a much-reduced data package, and so keeping them in or on the LTE ecosystem is imperative. To this end, LTE-U is a means to an end, even though it might make a lot more sense to install WiFi instead of LTE-U. Billing subscribers might prove a significant headache, however.

For IoT devices, WiFi still has a long way to go until it could provide a suitably low-power envelope, and so LTE-U seems more valuable for such devices – as long as the MulteFire adaptations are actually being used, and the range of the access point (likely a small cell) is enough for a mobile IoT device to make a connection when needed. However, if the small cell doesn’t have sufficient range, then the addition of LTE Cat-M or Cat-NB isn’t exactly much to cheer about. There’s not much point in a short-range WAN.

For now though, we’ll continue to pay close attention to how the L-LPWAN market develops. LTE-U could prove a Trojan Horse for these IoT-focused protocols, suddenly finding their way deep inside campuses and cities. However, the back-end services could remain the most challenging aspects. Unlike WiFi, which is simply moving IP packets to the address on the envelope, the MNOs would have to establish ways of paying each other for moving traffic over each other’s networks, and negotiate how something like a hospital’s LTE-U system feeds into the local MNOs’ core networks.

“The Release 1.1 Technical Specification is a significant achievement offering an optimized specification for IoT and support for additional spectrum bands,” said Mazen Chmaytelli, president, MulteFire Alliance. “This milestone could not have been reached without the dedication and commitment of the Technical Specification Group members who have worked tirelessly to evolve MulteFire technology to meet the needs of industrial IoT and enterprise.”