A New PRACH Transmission Scheme in Unlicensed Spectrum

For the unlicensed spectrum, the occupied bandwidth requirement is demanded by some regulations. The legacy scheme of Physical Random Access Channel (PRACH) for Long Term Evolution (LTE) cannot satisfy it. In this paper, we propose a novel PRACH transmission scheme to satisfy the requirement of unlicensed spectrum based on preamble pairing, and show some other candidates. We analyze and evaluate the key performances, including TA estimation accuracy, preamble multiplexing capability and cubic metric, of the proposed scheme and other candidates. Both theoretical analysis and simulation result show that our scheme outperforms the other candidates for the performances.