Impact of synchronization on performance of enhanced array-receivers in wideband CDMA networks

The synchronization performance of the receivers may severely impact the capacity or spectrum efficiency of wideband code division multiple access (CDMA) networks. Evaluations of the uplink capacity for improved spatio-temporal array receivers (STAR) and the two-dimensional RAKE (2-D-RAKE) with both perfect and active synchronization indicate that synchronization with the early-late gate component of a RAKE-type receiver may constitute a bottleneck to performance improvement. Enhancement of synchronization remains a key issue. Results also suggest that STAR offers a promising alternative to the 2-D-RAKE with early-late gate, offering an average increase in spectrum efficiency up to 100% in the presence of synchronization errors at both data rates of 9.6 and 128 kb/s. This gain further increases in high Doppler and fast multipath delay drifts. Data oversampling above the chip-rate favors STAR even more. Significant simplifications are introduced in the formulation of the STAR receiver which result in a complexity comparable to the 2-D-RAKE.