Circular polarized 60 GHz antennas

Many multimedia applications for high speed data wireless transmissions (around Gb/s or multi-Gb/s) are used in indoor systems (<10m). Some examples of them are the Ethernet Gigabit (1.25 Gb/s), the wireless high-speed download and the wireless transfer of high-definition video (2-20Gb/s). These high transmission rates cannot be implemented in the traditional frequency bands dedicated for the typical wireless systems, since they obtain an important degradation of service and the bandwidth is not enough for the data rate. For this reason, the Federal Communications Commission (FCC) has introduced recently 7 GHz of bandwidth, without license, in the band of 60 GHz. It is mainly due to the appearance of the atmospheric attenuation (10 to 15 dB/Km), since the presence of the oxygen affects in a bandwidth of 8 GHz (approximately) over the 60 GHz band; So the band of 60 GHz is not suitable for long distances (more than 2 Km). However, it is possible to dedicate completely in indoor wireless applications (<50m), where the atmospheric attenuation does not have any significant impact. This high bandwidth allows high speeds of data transmission and a new range of ultrahigh rates of the wireless communications systems. In consequence, the wireless highdefinition multimedia interface (wHDMI) and "Kiosk-downloading" are some applications with a high volume of information. It is important to highlight that wHDMI will offer an important improvement in the WLAN incorporated in the systems of portable computer (laptops, PDAs, etc ...). On the other hand, " Kiosk-downloading " is a possible solution to transfer, in a short time, DVD's movies from a server (kiosk) to a portable device such as iPods or PDAs. For example, the download of 120 minutes of a DVD would take 10 minutes with a rate of 54 Mb / s, whereas with this new technology would only take 13 seconds for a 2 Gb / s rate, and for 6 Gb / s rate it would only takes 4 seconds. In spite of the quantity of publications and the interest related to the 60 GHz band, it is possible to observe that the data rates of WLAN and WPAN increase periodically. For example, in 1999 the standard 802.11.b was allowing a maximum speed of 11Mb/s and in 2007 the rate was coming until 300Mb/s through the support to the project 802.11.n. Therefore, in 2011 it is possible to anticipate that a rate of a few Gb/s will be offered. Therefore, in order to satisfy the increasing demand of bandwidth, many enterprises and research institutions are investigating in new technologies to solve or at least to cover it temporally. For example, in March, 2005, the Group of Tasks 3C (TG3c) in IEEE802.15 was formed to coordinate the normalization of the 60 GHz band [12]. In order to contribute something to this investigation topic, this project is dedicated to the study of different antennas capable of working at the 60 GHz band and with the addition value of being circular polarized

Circular polarized 60 GHz antennas

Many multimedia applications for high speed data wireless transmissions (around Gb/s or multi-Gb/s) are used in indoor systems (<10m). Some examples of them are the Ethernet Gigabit (1.25 Gb/s), the wireless high-speed download and the wireless transfer of high-definition video (2-20Gb/s). These high transmission rates cannot be implemented in the traditional frequency bands dedicated for the typical wireless systems, since they obtain an important degradation of service and the bandwidth is not enough for the data rate. For this reason, the Federal Communications Commission (FCC) has introduced recently 7 GHz of bandwidth, without license, in the band of 60 GHz. It is mainly due to the appearance of the atmospheric attenuation (10 to 15 dB/Km), since the presence of the oxygen affects in a bandwidth of 8 GHz (approximately) over the 60 GHz band; So the band of 60 GHz is not suitable for long distances (more than 2 Km). However, it is possible to dedicate completely in indoor wireless applications (<50m), where the atmospheric attenuation does not have any significant impact. This high bandwidth allows high speeds of data transmission and a new range of ultrahigh rates of the wireless communications systems. In consequence, the wireless highdefinition multimedia interface (wHDMI) and "Kiosk-downloading" are some applications with a high volume of information. It is important to highlight that wHDMI will offer an important improvement in the WLAN incorporated in the systems of portable computer (laptops, PDAs, etc ...). On the other hand, " Kiosk-downloading " is a possible solution to transfer, in a short time, DVD's movies from a server (kiosk) to a portable device such as iPods or PDAs. For example, the download of 120 minutes of a DVD would take 10 minutes with a rate of 54 Mb / s, whereas with this new technology would only take 13 seconds for a 2 Gb / s rate, and for 6 Gb / s rate it would only takes 4 seconds. In spite of the quantity of publications and the interest related to the 60 GHz band, it is possible to observe that the data rates of WLAN and WPAN increase periodically. For example, in 1999 the standard 802.11.b was allowing a maximum speed of 11Mb/s and in 2007 the rate was coming until 300Mb/s through the support to the project 802.11.n. Therefore, in 2011 it is possible to anticipate that a rate of a few Gb/s will be offered. Therefore, in order to satisfy the increasing demand of bandwidth, many enterprises and research institutions are investigating in new technologies to solve or at least to cover it temporally. For example, in March, 2005, the Group of Tasks 3C (TG3c) in IEEE802.15 was formed to coordinate the normalization of the 60 GHz band [12]. In order to contribute something to this investigation topic, this project is dedicated to the study of different antennas capable of working at the 60 GHz band and with the addition value of being circular polarized

Web Service Testing and Usability for Mobile Learning

Based on the summary of recent renowned publications, Mobile Learning (ML) has become an emerging technology, as well as a new technique that can enhance the quality of learning. Due to the increasing importance of ML, the investigation of such impacts on the e-Science community is amongst the hot topics, which also relate to part of these research areas: Grid Infrastructure, Wireless Communication, Virtual Research Organization and Semantic Web. The above examples contribute to the demonstrations of how Mobile Learning can be applied into e-Science applications, including usability. However, there are few papers addressing testing and quality engineering issues – the core component for software engineering. Therefore, the major purpose of this paper is to present how Web Service Testing for Mobile Learning can be carried out, in addition to re-investigating the influences of the usability issue with both quantitative and qualitative research methods. Out of many mobile technologies available, the Pocket PC and Tablet PC have been chosen as the equipment; and the OMII Web Service, the 64-bit .NET e-portal and the GPS-PDA are the software tools to be used for Web Service testing

Enforcement and Spectrum Sharing: Case Studies of Federal-Commercial Sharing

To promote economic growth and unleash the potential of wireless broadband, there is a need to introduce more spectrally efficient technologies and spectrum management regimes. That led to an environment where commercial wireless broadband need to share spectrum with the federal and non-federal operations. Implementing sharing regimes on a non-opportunistic basis means that sharing agreements must be implemented. To have meaning, those agreements must be enforceable.\ud \ud With the significant exception of license-free wireless systems, commercial wireless services are based on exclusive use. With the policy change facilitating spectrum sharing, it becomes necessary to consider how sharing might take place in practice. Beyond the technical aspects of sharing, that must be resolved lie questions about how usage rights are appropriately determined and enforced. This paper is reasoning about enforcement in a particular spectrum bands (1695-1710 MHz and 3.5 GHz) that are currently being proposed for sharing between commercial services and incumbent spectrum users in the US. We examine three enforcement approaches, exclusion zones, protection zones and pure ex post and consider their implications in terms of cost elements, opportunity cost, and their adaptability

Fully integrated multi-optoelectronic synthesizer for THz pumping source in wireless communications with rich backup redundancy and wide tuning range

We report a monolithic photonic integrated circuit (PIC) for THz communication applications. The PIC generates up to 4 optical frequency lines which can be mixed in a separate device to generate THz radiation, and each of the optical lines can be modulated individually to encode data. Physically, the PIC comprises an array of wavelength tunable distributed feedback lasers each with its own electro-absorption modulator. The lasers are designed with a long cavity to operate with a narrow linewidth, typically &lt;4 MHz. The light from the lasers is coupled via an multimode interference (MMI) coupler into a semiconductor optical amplifier (SOA). By appropriate selection and biasing of pairs of lasers, the optical beat signal can be tuned continuously over the range from 0.254 THz to 2.723 THz. The EAM of each channel enables signal leveling balanced between the lasers and realizing data encoding, currently at data rates up to 6.5 Gb/s. The PIC is fabricated using regrowth-free techniques, making it economic for volume applications, such for use in data centers. The PIC also has a degree of redundancy, making it suitable for applications, such as inter-satellite communications, where high reliability is mandatory

LTE Spectrum Sharing Research Testbed: Integrated Hardware, Software, Network and Data

This paper presents Virginia Tech's wireless testbed supporting research on long-term evolution (LTE) signaling and radio frequency (RF) spectrum coexistence. LTE is continuously refined and new features released. As the communications contexts for LTE expand, new research problems arise and include operation in harsh RF signaling environments and coexistence with other radios. Our testbed provides an integrated research tool for investigating these and other research problems; it allows analyzing the severity of the problem, designing and rapidly prototyping solutions, and assessing them with standard-compliant equipment and test procedures. The modular testbed integrates general-purpose software-defined radio hardware, LTE-specific test equipment, RF components, free open-source and commercial LTE software, a configurable RF network and recorded radar waveform samples. It supports RF channel emulated and over-the-air radiated modes. The testbed can be remotely accessed and configured. An RF switching network allows for designing many different experiments that can involve a variety of real and virtual radios with support for multiple-input multiple-output (MIMO) antenna operation. We present the testbed, the research it has enabled and some valuable lessons that we learned and that may help designing, developing, and operating future wireless testbeds.Comment: In Proceeding of the 10th ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation & Characterization (WiNTECH), Snowbird, Utah, October 201

35 Gb/s Ultra-wideband Technology for Advanced Communications

The fast development of electronics and portable devices, intended mainly for multimedia applications, is increasing exponentially the data traffic demands per user. To cope with these new data demands in limited bandwidth systems, new technologies must be explored and new transmission schemes must be applied, evolving from classic spectral inefficient pulsebased systems to more advanced and flexible modulation schemes. Ultra-wideband technology is suitable for low-power high-speed wireless communication systems over short distances, and is an appealing alternative for next generation networks ranging from high-speed wireless personal area networks, to the internet of things applications. Its popularity stems from the fact that they can be used as an overlay to existing systems, without interference, operating in parallel to existing wireless systems, which perceive ultra-wideband emissions as ordinary noise. Furthermore, this technology allows unlicensed operation, provided standards and regulations are fulfilled. On the other hand, in current fast evolving scenarios, secure communications at the physical layer will soon become a requirement by the end users. Existing security techniques involve cryptography and other higher layer methods to secure the transmitted data, however, these are not capable to resolve entirely the psychological need for trust, especially in access scenarios where the user may be located in public spaces. We propose to use Ultra-Wideband communications technology, which can be seamlessly transported over fiber or wireless, and can provide high bit rates ranging from 2 Gb/s to 35 Gb/s. These record bit rates are achieved by means of the multiband approach of Carrierless Amplitude Phase modulation scheme, which offers high flexibility and enables to mitigate a wide range of channel impairments and comply different regulations worldwide. Summary form only given: The fast development of electronics and portable devices, intended mainly for multimedia applications, is increasing exponentially the data traffic demands per user. To cope with these new data demands in limited bandwidth systems, new technologies must be explored and new transmission schemes must be applied, evolving from classic spectral inefficient pulsebased systems to more advanced and flexible modulation schemes. Ultra-wideband technology is suitable for low-power high-speed wireless communication systems over short distances, and is an appealing alternative for next generation networks ranging from high-speed wireless personal area networks, to the internet of things applications. Its popularity stems from the fact that they can be used as an overlay to existing systems, without interference, operating in parallel to existing wireless systems, which perceive ultra-wideband emissions as ordinary noise. Furthermore, this technology allows unlicensed operation, provided standards and regulations are fulfilled. On the other hand, in current fast evolving scenarios, secure communications at the physical layer will soon become a requirement by the end users. Existing security techniques involve cryptography and other higher layer methods to secure the transmitted data, however, these are not capable to resolve entirely the psychological need for trust, especially in access scenarios where the user may be located in public spaces. We propose to use Ultra-Wideband communications technology, which can be seamlessly transported over fiber or wireless, and can provide high bit rates ranging from 2 Gb/s to 35 Gb/s. These record bit rates are achieved by means of the multiband approach of Carrierless Amplitude Phase modulation scheme, which offers high flexibility and enables to mitigate a wide range of channel impairments and comply different regulations worldwide