<p><b>The 3<sup>rd</sup> Generation Partnership
Project (3GPP) specification of the fifth generation (5G) New Radio (NR) allows
for a highly scalable and flexible radio access technology to cater to network
operators with different requirements. Such scalability and flexibilities in network configurations inevitably
translate to complications in the design
and implementation of 5G-NR systems. Radio access in 5G-NR is much more complex
and involved than its predecessor, 4G long
term evolution (LTE) and LTE-Advanced technology.
Therefore, the 5G-NR specifications turn out to be quite dense. Specifically, the
specifications are concise, design motivations rarely explained, and the
information can be convoluted or distributed across several documents.
Moreover, there are several key design details associated with the access layer
procedures for any given physical layer channel, which are often omitted in the
specifications. For example, design motivation aspects of initial access
channels or signal generation can be quite difficult to follow or understand in
5G-NR. In this paper, all the design details associated with initial access
channels and signal generation in 5G-NR specifications are laid out. The
contributions of the paper are three folds. First, <a>the
design details and justifications associated with both downlink and uplink
access channels are presented along with signal generation details. Secondly,
receiver design aspects of NR PRACH short formats are discussed. Lastly, PRACH receiver
implementation aspects and performance reports from different network operators
are presented and compared with 3GPP specified Radio Performance and Protocol
aspect requirements</a><a><b>[1]</b></a> for millimeter wave (mmW) access. The
work in this paper is of significant value to researchers and system engineers
looking to design and build initial access algorithms as part of 5G NR systems.
</b></p>
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<p><a>[1]</a> Radio Performance and Protocol aspect
requirements are specified by the 3GPP Radio Access Network working group 4,
also known as RAN4.</p>
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