This paper investigates the behavior of a wireless mesh network in which the nodes are equipped with a multiple antenna system. The objective of this study is the comparison of the low-cost switched-beam antennas with the more expensive fully adaptive smart antennas. The analysis and the simulations are performed together with some considerations regarding the advantages and the practical possibilities of employing multi-antenna systems on mesh routers. The analytical and the numerical results are derived employing realistic antenna radiation patterns and a proper spatial channel model.

This paper investigates the performance of a distributed wireless network in which the nodes are equipped with fully adaptive smart antennas. The main goal is the evaluation of the influence that the geometrical configuration of the antenna array has on network throughput and packet delay. Analysis and simulations are performed to study the relationship between the geometry of the antenna array and the network topology. In this paper, the performance degradation due to both the small-channel angular spreads and the speed of mobile nodes is investigated. The results, which hold for the low-rank channel model only, extend to this specific case previous results obtained in ideal channel conditions. The study adopts an access scheme, previously proposed for ad-hoc networks, which is able to exploit the interferer suppression capabilities of smart antennas, together with realistic models for the antenna and the channel behaviors.

This paper analyzes the maximum number of simultaneous communications that can be sustained by an ad-hoc network in which the nodes are equipped with fully adaptive smart antennas. The study proposes an analytical model for the evaluation of the performance of ad hoc networks which includes multipath together with some characteristics of the access scheme. The main goal is the analysis of the relationship between the angular spread of the channel and the transmission policy ruled at MAC layer. Moreover, in the paper, it is examined the influence of the spatial channel model on network performance.

The theory of the frequency down-converters, which use sinusoidally driven exponential junction diode, is reviewed here with the purpose of investigating the effects of the junction Capacitance on the conversion loss. The analysis deals With single-ended mixers, both in theZandYconfigurations. Their performances are compared with those obtained from the same configurations of mixers using a purely resistive (PR) exponential diode, in cases of both short-circuited and open-circuited image frequency. This comparison shows that the junction capacitance modifies strongly the behavior of the single-ended mixer compared tothe case of purely resistive diodes. It is pointed out that, when the junction capacitance may not be neglected, and the image frequency is either open- or short-circuited, good performance can still be achieved from a sinusoidally drivenYmixer. On the contrary, the sinusoidally drivenZmixer, which Operates better than theYmixer when the effect of the junction capacitance may be neglected, is strongly deteriorated, and it becomes worse than theYmixer.