Semi-Blind Multi-User Detection for LTE PUCCH

In long term evolution (LTE) specification, physical uplink control channel (PUCCH) consists of two basic transmission formats, i.e. formats 1a/1b and format 2, carrying some control signals fed back to eNodeB, e.g. ACK/NACK related to downlink data transmission blocks and downlink channel quality indicator (CQI). At eNodeB, conventional receiver detection algorithm is to do coherent data detection by utilizing reference signals (RS) based channel estimation, also called non-blind algorithm, whose detection performance is greatly limited by RS density and data coding rate. In this paper, a semi-blind algorithm is introduced to improve channel estimation accuracy by also using data energy besides RS energy at a cost of a higher computational complexity. The analyzes is done for both formats 1a/1b and format 2. Simulation results show that semi-blind algorithms efficiently improve the performance of format 2 because format 2 has lower RS density and higher coding rate than formats 1a/1b.