March 20, 2017

Uplink Contention Based Transmission with Non-Orthogonal Spreading

  • Li H.
  • Miao D.
  • Pedersen K.
  • Sun J.
  • Zhang Y.
  • Zhao Z.

The contention-based (CB) transmission is a promising solution for small data packets transmission in 5G uplink. In this paper, a Non-Orthogonal Coded Access (NOCA) scheme, called ZC-NOCA, is proposed for CB transmission in 5G uplink. For ZC-NOCA, the codes generated by Zadoff-Chu (ZC) sequences is used to spread the data bit over the Orthogonal Frequency Division Multiple (OFDM) symbols. Different with LTE, where ZC sequences keep inter-cell orthogonal, ZC-NOCA use both non-orthogonal and orthogonal sequences for spreading. A CB transmission channel design with ZC-NOCA for 5G uplink is presented, to combine the advantages of both orthogonal and non-orthogonal schemes. The link level performance of ZC-NOCA is investigated by using two types of multi user detection (MUD) receiver considering the user detection performed by preamble or directly by the spreading codes. The study show ZC-NOCA allow a large number of user overloading and enable massive connections employed with CB transmission. Compare to orthogonal code access scheme, with larger code book length ZC-NOCA enables to support more than 10x user connections with acceptable link performance loss in CB transmission.

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