| In this paper we study the system capacity of cellular systems with time-division multiple access and slow time-frequency hopping (F-TDMA). System capacity is deened as the number of users/cell bit/s/Hz, for a given maximum outage probability. Outage is deened as the event that the mutual information of the interference channel falls below the actual code rate. We develop a general framework ...

The optimization between the average received power and the theoretically achievable average channel capacity per user (in the Shannon sense) of a hybrid direct-sequence/fast frequency hopping codedivision multiple-access (DS/FFH-CDMA) cellular system, when operating in a Rayleigh fading environment, is presented. The analysis leads to a novel-closed form expression for the optimal average rece...

Smart antenna is considered as one of the most effective means for enhancing wireless system capacity. When fractional loading is accompanied with slow-frequency hopping (SFH), soft capacity can be realized in time-division multiple access (TDMA) wireless networks. Then, the interference reduction due to smart antennas, power control, and discontinuous transmission can be directly translated in...

in this paper, we have used density functional perturbation theory (dfpt) and pseudo-potential method to calculate the phonon spectrum, phonon density of states (dos), specific heat capacity and mechanical properties of (5,5) armchair and (9,0) zigzag single wall carbon nanotubes (swcnts). our calculations show that young’s modulusfor (5,5) and (9,0) nanotubesare higher than 1tpa. we have also ...

The error probability and capacity of a time-hopping ultra-wideband (UWB) communication system with receive diversity are investigated.We consider pulse amplitudemodulation (PAM) and pulse-positionmodulation (PPM) over additive white Gaussian channels for a single-user system. A multiuser environment with PPM is also investigated. It is shown that the communication distance and error performanc...

In practice, radio spectrums allocated to cellular networks are usually underutilized. To increase the spectrum usage efficiency, we studied spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks use either all uplink frequency sub-channels or their disjoint sub-sets, called spectrum underlay and spectrum overlay, respectively. Given these methods, the capacity ...

Cellular communication networks are plagued with redundant capacity, which results in low utilization and costeffectiveness of network capital investments. The redundant capacity can be exploited to deliver secondary traffic that is ultra-elastic and delay-tolerant. In this paper, we propose an analytical framework to study the capacity-delay tradeoff of elastic/secondary traffic in large scale...