Performance Analysis of Connection Establishment Under Beamforming in 5G NR Networks

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Name of the Speaker: Bommisetty Lokesh (EE18D412)
Guide: Dr. Venkatesh T.G
Venue/Online meeting link: ESB-244 (Seminar Hall)
Date/Time: 27th October 2022, 3.30p.m

High demand for reliability, low latency, seamless connectivity lead to the 5G era. 5G NR has gained importance in academic and industrial research communities in recent times as its millimetre wave (mmWave) band operations offer a promising alternative for next-generation wireless communications. For the initial connection establishment of User Equipments (UEs) with the base station (gNB), 5G cellular networks employ a random access procedure where UEs transmit a randomly choosen preamble for acheiving uplink synchronization and subsequent uplink grant. It is of utmost importance that we evaluate the factors that aid and those that limit the random access procedure in achieving its envisaged goal. In our work, we develop an analytical model for random access procedure for connection establishment in 5G when beamforming is employed. The random access medium is modelled as a multi-channel slotted Aloha system. We use an equilibrium point analysis framework to derive the performance metrics namely, the rate at which UEs can lock on to a gNB and the average and variance of the time taken by a new UE to establish connection with the base station. We analyse the impact of the retransmission limit and the number of available preambles for random access on the performance of connection establishment of a UE. Our analysis brings out the importance of the choice of base station configurations with respect to the user demographics of a 5G NR cell.

However, the susceptibility of mmWave signals to severe path loss and shadowing requires the use of highly directional antennas. Since the narrow beams are vulnerable to blockages, the interference behaviour becomes the key factor in building the network. Hence, we propose a blockage model by considering the distribution of buildings in the cell as a Poisson point process. We analytically derive the blockage probability using the queuing theory. The effective success probability of the random access procedure has been presented through extensive simulations.