This paper presents the miss-detection probability (MDP) of the Physical Random Access Channel (PRACH) with a short sequence for the 3GPP New Radio specifications in the presence of carrier frequency offset (CFO) in millimeter-wave bands. At a base-station receiver, the correlation of every repetition unit of the PRACH-preamble sequence between the received PRACH signal and the PRACH-preamble sequence candidates is computed using a matched filter in the frequency domain. This is followed by combining the correlations of the repeated PRACH-preamble sequences that correspond to the fast Fourier transform blocks in the time domain. The multiple correlations of the repeated PRACH sequences are combined by coherent combining with in-phase and quadrature components or by combining in squared form in the power domain, followed by the detection of the sequence and received timing of the desired PRACH. This paper first investigates the effect of the repetition of the PRACH-preamble sequence on reducing the MDP for various 3GPP Tapped Delay Line channel models in non-line-of-sight (NLOS) and LOS environments. Next, we establish the best combining method for the correlations of the repeated PRACH sequences from two candidates based on the PRACH MDP for various types of PRACH formats and for various subcarrier spacings (SCSs) from 120 kHz to 960 kHz in the presence of CFO based on extensive simulations. We also show that a wide SCS of up to 960 kHz is effective in reducing the PRACH MDP in the presence of CFO for the frequency stability of a set of user equipment of up to 3 ppm at the carrier frequency of 60 GHz.

This paper presents a hardware design of high throughput, low latency preamble detector for 3GPP LTE physical random access channel (PRACH) receiver. The presented PRACH receiver uses the pipelined structure to improve the throughput of power delay profile (PDP) generation which is executed multiple times during the preamble detection. In addition, to reduce detection latency, we propose an instantaneous preamble detection method for both restricted and unrestricted set. The proposed preamble detection method can detect all existing preambles directly and instantaneously from PDP output while conducting PDP combining for restricted set. The PDP combining enables the PRACH receiver to detect preambles robustly even in severe Doppler effect or frequency error exist. Using proposed method, the worst case preamble detection latency time can be less than 1 ms with 136 MHz clock and the proposed PRACH receiver can be implemented with approximately 237k equivalent ASIC gates count or occupying 30.2% of xc6vlx130t FPGA device.

This paper presents the optimum physical random access channel (PRACH) structure in terms of the number of control signaling bits accommodated and the transmission bandwidth based on the link budget in order to satisfy the coverage requirement for the single-carrier (SC)-FDMA based E-UTRA uplink. First, we present the design concept of the PRACH structure considering the purposes of the random access procedure in the E-UTRA. Simulation evaluations including a system-level simulation show that a PRACH comprising a 0.5-msec preamble sequence can convey a 6-bit control signal at the cell edge when the inter-site distance (ISD) is 500 m under full channel load conditions with one-cell frequency reuse. It is also shown, however, that a PRACH longer than one-sub-frame, e.g., 1.0 msec, is necessary to support the ISD of 1732 m assuming the same conditions. We also show that the best transmission bandwidth for the PRACH is approximately 1.08-4.5 MHz from the viewpoint of the misdetection probability, and a 1.08-MHz transmission bandwidth is suitable considering other aspects such as flexible resource assignment in the time domain and a small number of options in the transmission bandwidth.