On design of physical random access channel in high-speed railway LTE systems

2014 ◽  
Vol 59 (35) ◽  
pp. 5042-5050 ◽  
Author(s):  
Gang Wu ◽  
Hang Yuan ◽  
Wei Guo ◽  
Su Hu ◽  
Shaoqian Li
Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 508
Author(s):  
Alaa Omran Almagrabi ◽  
Rashid Ali ◽  
Daniyal Alghazzawi ◽  
Abdullah AlBarakati ◽  
Tahir Khurshaid

The 5th generation (5G) wireless networks propose to address a variety of usage scenarios, such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Due to the exponential increase in the user equipment (UE) devices of wireless communication technologies, 5G and beyond networks (B5G) expect to support far higher user density and far lower latency than currently deployed cellular technologies, like long-term evolution-Advanced (LTE-A). However, one of the critical challenges for B5G is finding a clever way for various channel access mechanisms to maintain dense UE deployments. Random access channel (RACH) is a mandatory procedure for the UEs to connect with the evolved node B (eNB). The performance of the RACH directly affects the performance of the entire network. Currently, RACH uses a uniform distribution-based (UD) random access to prevent a possible network collision among multiple UEs attempting to access channel resources. However, in a UD-based channel access, every UE has an equal chance to choose a similar contention preamble close to the expected value, which causes an increase in the collision among the UEs. Therefore, in this paper, we propose a Poisson process-based RACH (2PRACH) alternative to a UD-based RACH. A Poisson process-based distribution, such as exponential distribution, disperses the random preambles between two bounds in a Poisson point method, where random variables occur continuously and independently with a constant parametric rate. In this way, our proposed 2PRACH approach distributes the UEs in a probability distribution of a parametric collection. Simulation results show that the shift of RACH from UD-based channel access to a Poisson process-based distribution enhances the reliability and lowers the network’s latency.


Author(s):  
Yun-sung Lee ◽  
Jin-seok Lee ◽  
Jae-sung Lim ◽  
Hyung-won Park ◽  
Hong-jun Noh

2020 ◽  
Vol 14 ◽  

In this paper, we have analyzed and developed different types of algorithms related to 5G accessibility procedures for Non Standalone (NSA) and Standalone (SA) mode. The 5G accessibility depends on 5G radio parameters of each procedure, such as contention based Random access (CBRA), contention free random access (CFRA), Radio admission control (RAC), Radio resource control (RRC) and Radio bearer reconfiguration. The random access procedure for NSA is similar to SA mode. The goal is to improve the accessibility by optimizing timers and tune the main 5G radio parameters related to Random access channel (RACH), RRC reconfiguration and RAC procedures.


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