Which of the following drive 5G low latency? (Choose two.)

5G achieves ultra-low latency through a combination of radio access network (RAN) enhancements and core network architectural changes. A lower Time Transmission Interval (TTI) is a key RAN feature in 5G New Radio (NR). By using flexible numerology and mini-slots, the time required to schedule and transmit data over the air is drastically reduced compared to 4G LTE, directly lowering air-interface latency. Concurrently, Edge Clouds, implementing Multi-access Edge Computing (MEC), bring application processing and services from centralized data centers to the network edge, closer to the end-user. This significantly cuts down the round-trip time by minimizing data travel distance through the backhaul and core network, which is crucial for latency-sensitive applications.

A. Support of up to 1 billion of IoT and sensors devices per km2: This describes Massive Machine Type Communications (mMTC), a 5G capability focused on connection density, not low latency (which is part of URLLC).
C. Higher spectral efficiency: This primarily contributes to higher data rates and network capacity (enhanced Mobile Broadband - eMBB), not directly to the reduction of transmission and processing delays required for ultra-low latency.

1. Nokia. (2020). 5G New Radio highlights: The key features of the 5G air interface. White Paper. In the section "Ultra-low latency," it states, "5G NR introduces an extremely flexible and scalable frame structure... It allows for a much shorter transmission time interval (TTI) than the 1 ms used in LTE... This is a key enabler for ultra-low latency." (Reference to TTI).

2. Nokia. (2021). The value of edge cloud in the 5G era. White Paper. Page 4, Section "Why the edge cloud is needed," explains, "By moving computing power from a centralized location to the edge of the network... operators can significantly reduce latency... This is essential for new 5G-enabled services such as... URLLC use cases." (Reference to Edge Clouds).

3. Bennis, M., Letaief, K. B., et al. (2018). A Survey of URLLC for 5G: From Theory to Practice. IEEE Communications Surveys & Tutorials, 20(4), 3328-3364. https://doi.org/10.1109/COMST.2018.2857047. Section III.A, "RAN-Level Enablers," discusses mini-slot based scheduling (short TTI) as a key technology. Section III.B, "Network-Level Enablers," identifies Multi-access Edge Computing (MEC) as critical for reducing end-to-end latency by localizing traffic.