SNR estimation based on PRACH Preambles in LTE uplink

In the LTE systems, the PRACH receiver does cyclic cross-correlation to detect Preamble Index and estimate the Timing Advance used for uplink synchronization. Though Base Station receives noisy random access signal but usual PRACH receiver does not estimate noise and hence SNR is seldom touched. However if eNodeB has to schedule the L2/L3 message in a frequency-selective manner within the PRACH bandwidth and to have prior-knowledge for uplink channel condition then SNR estimation is requisite. This not only improves the system capacity but also improves performance. A novel SNR estimation based on received random access signal is proposed in this paper. The proposed algorithm performance is measured through Monte-Carlo simulations on a different channel models and the simulation results show that the algorithm closely resembles to un-biased SNR estimator with bias of ≤1dB for a wide SNR range.