Huawei and NTT DOCOMO undertake LAA field test

Licensed-Assisted Access (LAA) technology used listen before talk mechanism to enable fair use of unlicensed spectrum between cellular and Wi-Fi demonstrated in Tokyo

Huawei and NTT DOCOMO undertake LAA field test

Huawei has completed a live demonstration of the co-channel coexistence between cellular and unlicensed spectrum using Licensed-Assisted Access (LAA) technology. The trial mixed cellular and Wi-Fi systems in a dense small cell scenario targeting realistic LAA deployment in an unlicensed band.

The live demonstration was conducted jointly with NTT DOCOMO, Japan’s largest mobile service provider, during the DOCOMO R&D Open House 2015 held at the DOCOMO R&D Center in Yokosuka Research Park near Yokohama, Japan.

Huawei and DOCOMO showed LAA and Wi-Fi co-existence key technologies complying with standardised LAA in the 3rd Generation Partnership Project (3GPP), which is expected to be completed in Q1, 2016.

LAA is one of through approaches looking at ways for cellular technologies such as 4G LTE to co-exist with unlicensed spectrum technologies such as Wi-Fi in the unlicensed bands. LTE-Unlicensed (LTE-U) is the most controversial as it does not implement ‘listen before talk’ (LBT) mechanisms to avoid interference.

LAA uses 5GHz unlicensed spectrum for supplemental downlink to boost capacity of the host network in licensed frequencies and does implement LBT. The third approach is LTELWA (Wi-Fi Link Access) which splits the LTE data payload and tunnels some traffic over Wi-Fi inside 802.11ac frames, so it looks like Wi-Fi to other Wi-Fi networks in the same channel.

In this demonstration, different from a previous LAA demonstration held in July 2015, a multi-access points/multi-user small cell network was used to model a practical field test scenario, with an unlicensed carrier operating in air-interface rather than cable connection. According to Huawei, the results further confirmed the capability of LAA to provide fair co-existence, as well as robust performance and thus promising use of a real commercial network.

At the same time, an enhanced (while still 3GPP standardisation compatible) co-existence technology, called adaptive Listen-Before-Talk (LBT) proposed by Huawei, was tested in the demonstration. Due to the flexible resource reuse in both time and power domain, adaptive LBT can further achieve 50% LAA performance gain over baseline co-existence solution, while still providing fair co-existence to neighbouring Wi-Fi systems, the company claimed.

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