Random Access Procedure Based on Low-Density Signatures

Random-access is essential for any cellular system. In LTE, random-access is a part of a contention-based random-access procedure, where in the first step terminal transmits one randomly selected preamble. In this paper, we show that random-access can be enhanced if terminal may transmit more than one preamble and consider how to adapt random-access procedure to this case. This approach may be interpreted as application of a Low-Density Signature (LDS) structure to the orthogonal sequences and is referred to as LDS-OS.