Investigation on Optimum Coding and Multiplexing Schemes for L1/L2 Control Signals in OFDM based Evolved UTRA Downlink

This paper presents the optimum channel coding and multiplexing schemes for Layer 1 (Ll)/Layer 2 (L2) control signals for OFDM based radio access in the Evolved UTRA downlink. Simulation results show that separate channel coding of downlink-related L1/L2 control signals is superior to joint coding among simultaneous accessing user equipments (UEs), from the viewpoint of the required total symbol energy of the L1/L2 control signals. The results also show that time division multiplexing (TDM) based multiplexing associated with transmission time interval (TTI)-by-TTI frame format control employing a control channel format indicator (CCFI) achieves almost the same cell throughput as that for frequency division multiplexing (FDM). Therefore, considering the advantages of TDM such as the possibility of a power saving effect through micro-sleep operation and a short control loop delays for scheduling, adaptive modulation and coding, and hybrid ARQ, we conclude that TDM based multiplexing of L1/L2 control signals with a shared data channel is superior to using FDM based multiplexing.