||Cell search of Third Generation Partnership Project Long Term Evolution (3GPP LTE) includes time synchronization and frequency synchronization of frames, and the acquisition of Cell Identity (Cell ID). The LTE systems use 504 Cell IDs divided into 168 unique Cell-Identity Groups (Cell-ID Groups), and each Cell-ID Group comprises three Sector Identities (Sector IDs). After reaching synchronization of time and frequency between frames, the Cell ID acquisition scheme provided by specification of 3GPP LTE is consisted of two steps, the first step must utilize three matched filters to detect one out of three Sector IDs, and then implement coherent correlation detection between 168 Pseudo Random Noise Sequences (PN sequences) to obtain the index of Cell-ID Group.|
So the cell search scheme provided by LTE standard has to detect correlation of all sequences, and computed complexity brings considerable processing time to effect the delay time of services power on, standby time, energy saved, and cost of manufacture. To reduce complexity, we propose a perfect sequence with special structure as preamble, and the sequence is linear combination of two base sequences. We put the sequences within Primary Synchronization Channel (P-SCH) and Secondary Synchronization Channel (S-SCH), and we utilize the phase rotation factors of the sequences as index to generate Cell ID, instead of the current scheme to generate Cell ID with the indexes between sequences and sequences. Based on the sequences in multipath channel model, simulation results verify the detection probability of Cell IDs by proposed scheme is 100% when SNR is -8dB, and it is 98.7% by the scheme in LTE specification after perfect time and frequency compensation. Except that, Cell ID detection performance is similar without channel compensation to reduce implement complexity.
Index Terms- cell search, 3GPP LTE, 16n perfect sequence.