Sub-chip-level detection in 2-D optical code division multiple access under the chip asynchronous assumption

In this paper, we propose a "sub-chip-level" receiver for two-dimensional (2D) optical code division multiple access (O-CDMA). In a chip-level receiver, one detects the total received optical intensity in a chip time. In our sub-chip-level receiver, we detect the received optical intensity in multiple sub-chip intervals in order to further reduce decoding errors. Afterwards, the "chip-asynchronous" performance of 2D optical codes with arbitrary cross-correlation values in the sub-chip-level receiver is analyzed as a function of the number of sub-chips. The performance is also compared with that of the chip-level receiver under the chip-asynchronous assumption.