Modified dynamic DF for type-2 UE relays

Abstract

A dynamic decode-&-forward (DDF) is redesigned to meet the crucial requirements for type-2 user equipment (UE) relays which are being considered for next-generation cellular standards (e.g., LTE-Advanced). Toward this, the proposed modified DDF (M-DDF) realizes a fast jump-in relaying and sequential decoding where a subframe decoding is employed to yield a combination of energy/information/mixed combining, in conjunction with the random codeset for encoding and re-encoding at source and multiple UE relays, depending on their channel conditions. These additional features existing in the M-DDF circumvent the need of exchanging control messages between multiple relays and end user near cell boundary, which is not allowed for type-2 UE relays. Through comparison among the DDF with single and multiple orthogonal channels and M-DDF, the M-DDF bridges the gap between former relaying protocols with application to type-2 UE relays, offering reliable rate capacity with less channel usage and further improvement, if the early termination of decoding is made available. © 2012 IEEE.