A base station maps a first Transmission Time Interval (TTI) configuration associated with a carrier of a RAN to a first RAN slice. The first RAN slice is configured to support a first Quality of Service (QoS) requirement. The first TTI configuration comprises a first number of Orthogonal Frequency-Division Multiplexing (OFDM) symbols. The base station maps a second TTI configuration associated with the carrier to a second RAN slice. The second RAN slice is configured to support a second QoS requirement different from the first QoS requirement. The second TTI configuration comprises a second number of the OFDM symbols and is different from the first TTI configuration. The OFDM symbols with respect to the first and the second RAN slices are defined according to a single numerology. The base station informs a UE of the first and second TTI configurations mapped respectively to the first and second RAN slices.