This letter presents a new probability expression for a multi-carrier (MC) DS/CDMA acquisition system with a reference matched filter (RMF). To evaluate the mean acquisition time (MAT) as a measure of the system performance, the probabilities of detection, miss, and false alarm are derived. From the results, it is shown that the MAT of the MC-CDMA hybrid system with RMF is comparable to the optimum mean acquisition time of the conventional MC-CDMA hybrid system, maintaining approximately the same degree of structuring complexity.

Both tiers are assumed to share the same frequency band. Unlike a single tier cell environment, interference components to be considered in a hierarchical cell environment include the inter-tier interference as well as the intra-cell and the inter-cell interference. The numerical results show that the transmission power ratio between the macro cell and the micro cell affects the forward link capacity. And the results also show that the macro cell capacity increases as the mobile moves toward the edge of the macro cell. Moreover, soft handoff makes it possible to obtain a higher forward link capacity in the handoff region.

We study threshold-based relaying in an amplify-and-forward (AF) cooperative diversity network. For the network, the relay helps the communication from the source to the destination only if the signal-to-noise ratio (SNR) of the link from the source to the relay is greater than or equal to a pre-determined threshold value; otherwise, the relay remains silent. We derive the exact bit-error rate (BER) of the threshold-based relaying for M-pulse amplitude modulation (PAM) and M-quadrature amplitude modulation (QAM). The obtained BER expression can help the design of the threshold-based relaying in determining the system parameters such as the transmission power, the amplifying coefficient at the relay, and the pre-determined threshold value.

This letter evaluates the peak-to-average power ratio (PAR) performance in a space-time block coded (STBC) multicode CDMA (MC-CDMA) system using a selected mapping (SLM) approach. The ordinary method is to apply the SLM scheme for each transmit antenna individually, while the investigated SLM-based STBC MC-CDMA system selects the transmitted sequence with the lowest average PAR over all transmit antennas concurrently. SLM-based STBC MC-CDMA system retrieves the side information very accurately at the expense of a slight degradation of the PAR performance, which can improve the overall detection performance of the STBC MC-CDMA system in the presence of erroneous side information compared to the ordinary SLM approach.