In virtual cellular network (VCN), proposed for high-speed packet mobile communications, the signal transmitted from a mobile terminal is received by wireless ports distributed in each virtual cell and relayed to the central port that acts as a gateway to the core network. In this letter, we apply the multi-hop maximal ratio combining (MHMRC) diversity and propose the route modification algorithm in order to improve transmit power efficiency degradation caused by the carrier frequency difference between the control and the data communication channels for VCN. The transmit power efficiency and the distribution of the number of hops are evaluated by computer simulation for a VCN.

In this paper, we study a delay transmit diversity system combined with antenna diversity reception that transmits the time-delayed and weighted versions of the same signal from multiple antennas. At a receiver, multiple receive antennas are used and all delayed signals received on multiple antennas are coherently combined by a Rake receiver. The set of optimum antenna weights for maximizing the received signal-to-noise power ratio (SNR) after Rake combining is theoretically analyzed to show that the optimum solution is to transmit only from the best antenna that has the maximum equivalent channel gain seen after Rake combining. The bit error rate (BER) performance is theoretically analyzed and evaluated by computer simulation. The combined effect of transmit diversity and transmit power control (TPC) is also investigated.

In this paper, expressions are derived for the bit error rate (BER) of the multicarrier-CDMA (MC-CDMA) downlink in the presence of pure impulsive interference and a frequency-selective fading and the BER performance is numerically evaluated by a Monte-Carlo simulation method. Minimum mean square error combining (MMSEC) and orthogonal restoration combining (ORC) are considered for frequency-domain equalization. The joint weight of antenna diversity reception using maximal ratio combining (MRC) and frequency equalization combining is derived. The MC-CDMA transmission performance in the presence of pure impulsive interference is compared with that of DS-CDMA transmission.

Independent shadowing losses are often assumed for computing the frequency reuse distance of cellular mobile communication systems. However, shadowing losses may be partially correlated since the obstacles surrounding a mobile station block similarly the desired signal and interfering signals. We investigate, by computer simulation, how the shadowing correlation impacts the frequency reuse distance of a power controlled cellular system. It is pointed out that the shadowing correlation impacts the frequency reuse distance differently for the uplink and downlink.

Without transmit power control (TPC) and Rake combining, the uplink capacity of a direct sequence code division multiple access (DS-CDMA) packet mobile communication system significantly degrades due to the near-far problem and multipath fading. In this letter, assuming a single cell system with an interference-limited channel, the impact of the joint use of Rake combining and TPC on the uplink capacity is evaluated by computer simulation. Slow TPC is found to give a link capacity larger than fast TPC. This is because, with slow TPC, the received signal power variations due to fading remain intact and this results in a larger capture effect.

A random transmit power control (TPC) is applied to DS-CDMA/TDD packet mobile radio, which controls the transmit power so as to intentionally vary the received signal power in order to obtain the large capture effect. The uplink capacity with the random TPC in a frequency-selective fading channel is evaluated by computer simulation. The simulation results show that the random TPC provides larger link capacity than slow TPC.

Four imperfections encountered in transmitter power control (TPC) for direct sequence code division multiple access (DS/CDMA) cellular mobile communications systems, faulty TPC, finite dynamic range, restricted site diversity, and non-uniform user distribution, are investigated where account is taken of the effect of the propagation constant on the traffic capacity. Computer simulation schemes for traffic capacity estimation under these TPC imperfections are presented. Traffic capacity estimates are produced for a representative DS/CDMA cellular mobile communications system.

Recently, major services provided by mobile communications systems are shifting from voice conversations to data communications over the Internet. There is a strong demand for increasing the data transmission rate. However, an important problem arises; larger peak transmit power is required as transmission rate becomes higher. In this paper, we propose a wireless multi-hop virtual cellular concept to avoid this power problem. The virtual cellular network consists of a central port, which is a gateway to the network, and many distributed wireless ports. Transmit power and frequency efficiencies of the virtual cellular network are evaluated by computer simulation to compare with that of the present cellular networks. In the wireless multi-hop virtual cellular network, routing among wireless ports is an important technical issue. We propose a routing algorithm based on the total uplink transmit power minimization criterion and evaluate the total transmit power by computer simulation.