To meet increasing applications of Internet of Things (IoT), the 3rd generation partnership project has specified Narrow Band Internet of Things (NB-IoT) standard. However, collisions in NB-IoT physical random access channel (NPRACH) can be severe due to mismatch between frequent random access requests of a huge number of devices and limited available preambles. In this paper, we propose to use non-orthogonal frequency hopping between preambles and introduce controllable partial collisions to effectively avoid full preamble collisions. This will increase available preambles and thus reduce preamble collision significantly. The proposed hopping pattern maintains compatibility with the current standard NB-IoT system, by keeping NPRACH structure in standard with minimal change. Simulation results show that the proposed frequency hopping pattern can greatly increase accessing devices due to collision avoidance while slightly reducing detection probability.
An Improved NPRACH Preamble Frequency Hopping Pattern for Reducing Preamble Collision
2023-10-10
986029 byte
Conference paper
Electronic Resource
English
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