Balanced-Offset Joint Acquisition of Physical Cell Identity and Radio Frame Number for NB-IoT Communication Systems

This article proposes a reduced complexity synchronization signal detection scheme in a narrowband Internet of Things (NB-IoT) system. By detecting the narrowband secondary synchronization signal (NSSS), both physical cell ID (PCID) and radio frame number (RFN) are jointly obtained during the initial cell search procedure in NB-IoT. To facilitate reduced complexity joint detection of the PCID and RFN, we propose an NSSS subcarrier grouping method by balancing the phase offset among NSSS subcarriers. The advantages and drawbacks of the proposed joint detector are presented by comparing the conventional joint detector in terms of performance and complexity. The probability of detection failure of the proposed detector is theoretically derived, which is further validated by means of simulation results. Both analytical results and simulations show that the proposed solution significantly decreases the computational burden with negligible performance loss, compared to the conventional detectors.