With all the rage over 5G technology, do you really know its technical complexities? Here is a quick technical refresher…
Put simply, 5G is not simple an upgraded older technology we know as 4G. The technology is drastically different from previous generations of cellular technology, according to Jessy Cavazos, 5G Industry Solutions Manager, Keysight Technologies.
Here are some key points offered by her to give a quick review of the technical characteristics and challenges of the technology:
5G operates in two frequency ranges: from 410 MHz to 7.25 GHz (frequency range 1 or FR1) and from 24.25 to 52.6 GHz (frequency range 2 or FR2). A single component carrier now has up to 400 MHz of channel bandwidth and the channel properties of higher frequencies require the use of different multiple-input/multiple-output (MIMO) variants for each frequency range.
Using orthogonal frequency-division multiplexing (OFDM) modulation, each channel bandwidth has an underlying resource grid underneath. The numerology changes depending on how far apart the subcarriers are.
5G bandwidth parts
To address different applications and use cases, it is important to understand the underlying resource grid of 5G channels and how 5G uses waveforms and modulation schemes to optimize signals for various scenarios. Enabling these applications requires significant technical advancements and a complete overhaul of the cellular network.
It is also important to understand the protocol structure for 5G as there are notable changes including a new service data adaptation protocol (SDAP) layer for Quality of Service (QoS) management in the user plane, and a new feature enabling packet data convergence protocol (PDCP) duplication for mapping packet data units (PDUs) to more than one logical channel and sending them over different component carriers.
Also, the radio link control (RLC) and the media access control (MAC) layers now support beam management procedures and transmission modes using different numerologies and transmission time intervals.
New additions to the physical channels include phase tracking reference signal (PTRS) for tracking phases and time scheduling, demodulation reference signal (DMRS) for the uplink control channel, and using the downlink broadcast channel.
The move to mmWave frequencies in 5G brings beamforming and beam management challenges to design and test engineers.
Handling high signal loss
Using more transmit/receive (Tx/Rx) antennas compensate for the high loss at these frequencies. More radiating elements enable steering the direction of the antenna. The beams also become narrower and more defined, increasing received power to the user equipment. However, lossy cables and greater device/system integration drive testing to be mostly done over the air.
With all the technical issues covered, 5G can boost not only cellular communication performance but also expand beyond cell phones to encompass virtual and augmented reality, vehicle-to-everything (V2X) communications; the industrial internet of things (IIoT), and bring communications services to new places through satellite technology.
