5G — Traffic Demands & Business in the Digital Society of 2020 : Part II
Marco Giordani, Ph.D. Candidate in Information Engineering at University of Padova &
continues the tete-a-tete on the 5G paradigm.5G systems introduce unprecedented requirements in terms of data rate, latency, link resilience, and end-to- end reliability, which go beyond what existing mobile technologies can support and which call for innovative breakthrough technological advancements and novel network designs.
In this perspective, the millimeter wave (mmWave) spectrum — roughly between 10 and 100 GHz — has rapidly emerged as an enabler of the 5G performance demands in micro and picocellular networks.
These frequencies, combined with high-order modulation, offer much more bandwidth than 4G/LTE systems operating in the congested bands below 6 GHz, and initial capacity estimates have suggested that networks operating at mmWaves can offer orders of magnitude higher bit-rates than legacy cellular networks. Moreover, mmWave systems operate through highly directional communications which tend to isolate the users and deliver reduced interference. Additionally, inherent security and privacy is also improved because of blockage and of the short-range transmissions which are typically established.
Although communication at mmWaves introduces new challenges for the whole protocol stack (e.g., signals propagating in the mmWave spectrum suffer from severe path loss, susceptibility to shadowing, and are highly sensitive to blockage), the 3rd Generation Partnership Project (3GPP) is boosting the 5G performance by sup- porting, for the first time, frequencies up to 52.6 GHz in Release 15, including therefore mmWave bands.
Massive Multiple Input Multiple Output (MIMO) techniques have also emerged in modern wireless networks to improve 5G reliability and spectral efficiency. The main concept is to use multiple transmit and receive antennas (e.g., with 100 or more elements) to exploit multipath propagation. Depending on the channel proprieties, MIMO systems can be configured for:
- Spatial diversity, i.e., making links more robust by transmitting redundant versions of the same message over multiple paths.
- Beamforming, i.e., providing antenna gains by forming a concentrated beam pattern towards a specific direction.
- Spatial multiplexing, i.e., providing throughput gains by splitting an outgoing signal into multiple independent streams which are transmitted in parallel on the same channel through different antennas.
Other 5G innovations include a flexible design of the air interface and novel deployment paradigms, as we will see in the next post. Stay tuned.
