Wireless personal communication systems grow very fast, and the Code Division Multiple Access (CDMA) system has become the key technology for multiple accesses in the third generation communication systems. Unlike conventional FDMA and TDMA systems, the capacity of CDMA is limited by the interference. Moreover, the quality of the wireless communications varies with the terrain and the location,...

adequate coverage is one of the main problems for distributed wireless sensor networks and the effectiveness of that highly depends on the sensor deployment scheme. given a finite number of sensors, optimizing the sensor deployment will provide sufficient sensor coverage and save power of sensors for movement to target location to adequate coverage. in this paper, we apply fuzzy logic system to...

in mobile ad hoc networks, the absence ofinfrastructure and the consequent absence of authorizationfacilities impede the usual practice of establishing a practicalcriterion to distinguishing nodes as trusted and distrusted.since all nodes in the manets would be used as router inmulti-hop applications, secure routing protocols have vital rulein the security of the network. so evaluating the perf...

A limited amount of bandwidth is allocated for wireless services. A wireless system is required to accommodate as many users as possible by effectively sharing the limited bandwidth. Therefore, in the field of communications, the term multiple access could be defined as a means of allowing multiple users to simultaneously share the finite bandwidth with least possible degradation in the perform...

This paper presents virtual clusters based proportional fairness and resource allocation scheme for Localized Single Carrier Frequency Division Multiple Access (L-SC-FDMA). L-SC-FDMA has been selected as the uplink transmission scheme in 3GPP Long Term Evolution (LTE) due to its low Peak to Average Power Ratio (PAPR) over OFDMA in general and high rate-sum capacity over Interleaved SC-FDMA in p...

Single-carrier (SC) multiple access is a promising uplink multiple access technique because of its low peak-to-average power ratio (PAPR) property and high frequency diversity gain that is achievable through simple one-tap frequency-domain equalization (FDE) in a strong frequency-selective channel. The multiple access capability can be obtained by combining either frequency division multiple ac...

Wireless technologies are an essential communication means that transform a branched localized fixed meshwork into a ubiquitous disconnected network. A clear trend shows that cells are becoming smaller, homogeneously distributed, operating at higher carrier frequencies, and more energy conscious. This points toward wireless picocell systems that implement millimeter-wave (mm-wave) modulation. I...

network sensors consist of sensor nodes in which every node covers a limited area. the most common use ofthese networks is in unreachable fields.sink is a node that collects data from other nodes.one of the main challenges in these networks is the limitation of nodes battery (power supply). therefore, the use oftopology control is required to decrease power consumption and increase network acce...