Uplink Frequency Bands Research Articles

Resource Allocation Method of Device-to-Device Communication

In this paper, we study D2D (Device-to-Device) communication underlying LTE-Advanced uplink system. Since D2D communication reuses uplink resources with cellular communication in this scenario, it’s hard to avoid the inference between D2D users and cellular users. If there is no restriction for D2D communication on using the whole uplink frequency band, it will have a strong negative impact on cellular communication. In order to overcome this shortage, we propose a resource allocation method that D2D users and cellular users use orthogonal frequency resources. This method will effectively reduce the inference between both kinds of communication. However, an obvious disadvantage of this method is no effective use of uplink resources. Based on this, we propose an optimized resource allocation method that a specific cellular user will be chosen to reuse the RBs (Resource Block) of D2D users. These ideas will be taken into system-level simulation, and from the results of simulation we can see that the optimized method has the ability to improve overall system performance and limit inference for cell-edge users.

Spectrum Correlated Criteria and Their Impacts on High Altitude Platform Station (HAPS) and Fixed Satellite Service (FSS) Coexistence in Frequency Range 5,850–7,075 MHz

High altitude platform station (HAPS) is an innovative technology which delivers some unique features, contrary to conventional communications networks, such as fixed satellite service (FSS). The absence of confirmed spectrum emission mask (SEM) of HAPS and its diversity to work within FSS networks are significant issues in evaluating the coexistence of HAPS and FSS. At this juncture, a practical SEM for HAPS gateway links is proposed which will endeavor to assess its functionality and its ability to coexist with FSS. HAPS SEM's impact on coexistence issues are exposed upon consideration of criteria such as MD, NFD and ACIR. These facets are well-described and their measured amounts for specific applicable SEMs are proposed. Therefore, reckoning process regarding these factors is ascertained. It must be said that the remarked criteria and their amounts for HAPS gateway links are unprecedented. The simulation parameters are well organized based upon International Telecommunication Union and World Radiocommunications Conferences periodicals. The aim of this article is to shed more light on the associated facets of the HAPS network spectrum and their impressions on HAPS and FSS networks coexistence. The assessments have been performed for HAPS gateway links in the 5,850---7,075 MHz frequency band where FSS uplink frequency band in C-band (5,925---6,725 MHz) partially intrude with HAPS gateway links. Therefore, HAPS gateway links channelization regarding FSS uplink channel is appraised and light is shed on the impact of HAPS and FSS coexisting in the same frequency band.

Compact dual-band axially corrugated profiled horn for prime-focus reflector antenna

This paper reports a new compact dual-band axially corrugated profiled horn feed (DBCPH) for prime-focus reflector antenna at C-band (uplink and downlink frequency bands with bandwidth ratio of 1.6). DBPCH consists of one sinusoid profiled section and two internal axial corrugations (internal short-circuited ring slots), for obtaining a multimode horn feed. Such a blended structure is optimized over the specified frequency bands (3.68–3.70 and 5.865–5.915 GHz) to achieve various performance objectives (such as compactness, return loss, polarization purity, etc.). Measured and predicted results show that DBCPH provides better return loss >18.6 dB, low cross-polarization (better than −32 dB), and adequate edge taper at ±48° (8.5–11.7 dB) along with compact size (1.3λ aperture diameter and 0.88λ length at lower frequency). The horn would be used as a feed element for front-fed prime-focus reflector for pencil beam spacecraft antenna application.

Compact High-Performance Reflector-Antenna Feeds and Feed Networks for Space Applications [Antenna Applications

Reflector antennas are widely used on satellites to communicate with ground stations. They simultaneously transmit and receive RF signals using separate downlink and uplink frequency bands. These antennas require compact and high-performance feed assemblies with small size, low mass, low passive intermodulation (PIM) products [1], low insertion loss, high power handling, and low cross-polar levels. The feeds must also be insensitive to large thermal variations, and must survive the launch environment. In order to achieve these desirable features without prototyping and/or bench tuning, Custom Microwave Inc. (CMI) has combined integrated RF design, precision CAD, and a precision manufacturing technique known as electroforming to closely integrate the various components of a feed or feed network, thereby achieving small size while maintaining high RF performance [2]. In addition to close integration, electroforming eliminates split joints and minimizes flanges by allowing several components to be realized in a single piece, making it the ideal manufacturing technique for ultra-low passive-intermodulation applications. This paper describes the use of precision design CAD tools along with electroforming to realize high-performance feed assemblies for various communication frequency bands for fixed satellite, broadcast satellite, and broadband satellite services.

Design of Dual-Band Multimode Profiled Smooth-Walled Horn Antenna for Satellite Communication

This letter is concerned with design and development of a new dual-band multimode profiled smooth-walled horn (DBPH) at Ku-band (uplink and downlink frequency bands). The horn is analyzed and optimized using mode-matching-technique-based software (Mician ? Wave wizard). Predicted radiation patterns and properties of the DBPH are compared to corresponding measured results showing good agreement. Relatively higher edge of coverage (EOC) gain and low cross-polar level at EOC is achieved with optimized DBPH by synthesizing higher order modes TE1m and TM1m in proper ratio of amplitude and phase. An innovative modified hyperbolic profile is used to optimize the various performance objectives. The DBPH also provides higher bore-sight gain, higher aperture efficiency, and slightly wider beam (i.e. lower roll-off) in comparison to a conical horn having similar aperture dimension and length. The horn would be used as an element of a direct radiating horn cluster for multibeam satellite antenna application.

Fast and slow light generated simultaneously for up–down-link frequency converter applications

We firstly propose a new system for simultaneous fast and slow light generation using a soliton pulse propagating within the nonlinear micro-ring resonators. The nonlinear Kerr effect induces the spreading frequency bands within the micro-ring device, where the chaotic filtering characteristics can be employed using the appropriate micro-ring parameters. Results obtained have shown that the wide spreading of frequency bands can be generated and selected to form the optical wireless communication links. In this work, the selected down-link and up-link frequency bands are 500 MHz and 2 GHz, respectively. The proposed system can be implemented within the mobile telephone hand set, where the two different frequency carriers within the same frequency bands can be selected to form the up–down-link converters, which means that the frequency converter can be performed within a single system.

Generalized optical filters using a nonlinear micro ring resonator system

We present the interesting results of nonlinear behaviors of a soliton pulse within a nonlinear micro ring resonator system, where the optical filter characteristics in terms of frequency, wavelength and time can be functioned by using the chaotic filter within the micro ring resonator system. There are three forms of applications using the chaotic soliton behaviors and optical filter characteristics presented. Firstly, the simultaneous up-link and down-link frequency bands can be filtered and the required frequency bands obtained. Secondly, we propose the simple system of an extremely narrow light pulse generation over the spectrum range, where the required wavelengths can be filtered and obtained. Finally, a simple system of fast light generation by using a soliton pulse circulating in the integrated micro ring devices is proposed. Using such a system, an attosecond pulse and beyond can be easily filtered and obtained.

1800 MHz in vitro exposure device for experimental studies on the effects of mobile communication systems

A wire patch cell (WPC) operating at the uplink frequency band of GSM 1800 MHz has been designed for in vitro experiments with the aim of investigating the possible biological effects of electromagnetic radiation associated with cellular phones. The 1800 MHz WPC design is a direct descendant of the original 900 MHz WPC introduced by Laval et al. This system provides a homogeneous specific absorption rate distribution, using four 3.5 cm petri dishes simultaneously. Numerical dosimetry has been performed using a commercial code (CST Microwave Studio), in order to evaluate accurately the efficiency of the structure (in terms of W kg(-1) per 1 W input power) and the distribution in the chosen biological target. The numerical results have been confirmed by experimental measurements performed by measuring thermal increase due to a high power impulse. The efficiency of the structure is 1.25 +/- 25% W kg(-1) per 1 W input power higher than the efficiency of the 900 MHz WPC. A few adjustments have been made in order to use the WPC in a standard incubator and to avoid thermal increases related to the radio frequency exposure. This exposure system has been adopted for the experiments scheduled in the RAMP and GUARD projects (VFPE).

Cell planning scheme for WCDMA systems using genetic algorithm and measured background noise floor

WCDMA is an interference-limited system and its coverage and data throughput are sensitive to background noise. The results of background noise measurements in urban Taipei city for the licence bands of 3G systems issued in Taiwan are presented. The measurements involve FDD mode uplink and downlink frequency bands measured on building tops and at street level, respectively. The severeness of spectrum pollution of these bands is evaluated by extracting three statistical parameters from the measurement data, and the impact of the background noise on coverage and throughput is analysed for WCDMA systems. Also, based on measurement results, a better solution using a genetic algorithm with the help of a propagation model and digitised building information is proposed for the deployment of the base stations of WCDMA systems, by which the required coverage can be met with a suitable number of base stations, locations, antenna heights and transmitting power. A system is obtained that suffers less impact from background noise and achieves a higher data throughput with minimum cost.

Analysis of smart antenna outage in UTRA FDD networks

The outage occurring from beamformer-based smart antennas is analysed for an antenna array deployed in an urban macro-cell environment. Spatio-temporal channel data obtained from a small, urban cell and from within the UTRA frequency allocation has enabled beamforming performance to be determined from the measured uplink and downlink frequency bands. The analysis shows a sub-optimum uplink beamformer performance is observed for 8% of occasions and a 25% downlink beamforming outage for an eight-element uniformly spaced linear array.

A transportable satellite ground station for television relay

Since 1978 IBA has been experimenting with a transportable satellite ground station designed to transmit television signals via the OTS satellite using the 14 GHz up-link frequency band. The aim of these experiments has been to develop the use of transportable satellite up-links for reporting news and events by satellite on a national and international scale. The paper describes the background to the requirement for such terminals and reports on the technical results obtained.The practical experience gained has made it possible to define the desirable features of operational terminals of this type and these are considered.The future for television news reporting via satellite will depend on the economics of this method in comparison with others and on whether satisfactory technical and regulatory methods can be devised to safeguard the use the geostationary orbit. The extent of these problems and the possible solutions are considered.

Effects of precipitation on 15.3- and 31.65-GHz earth—Space transmissions with the ATS-V satellite

The increased communications demands of a rapidly expanding technology are requiring the systems designer to look to higher frequency bands to support high data rate communications links. Virtually all terrestrial and satellite communications systems presently in service operate in bands below 10 GHz. The frequency band from 10 to 300 GHz, commonly called waves, offers the potential for relieving the overcrowded situation at the lower frequencies. The propagation characteristics of millimeter wavelength transmission are significantly different than at the longer wavelengths, however, and propagation data is required by the systems designer as a first step in evaluating the performance characteristics of operational links. The Applications Technology Satellite (ATS-V) millimeter wave propagation experiment is the first flight experiment for the determination of long- and short-term attenuation statistics of operational millimeter wavelength earth-space links as a function of defined meteorological conditions. The ATS-V experiment, launched August 12,1969, is providing the first propagation data from an orbiting geosynchronous spacecraft in the 15-GHz (downlink) and 32-GHz (uplink) frequency bands. Several stations in the continental U.S. and Canada have been operating with the downlink transmission from the satellite since late September 1969. The spacecraft transmitter is an all solid-state phase modulated unit that provides up to 250 mW of CW power at 15.3 GHz. The 31.65- GHz uplink signal is derived from a frequency stabilized klystron, varactor upconverter, and 1000 W traveling wave tube amplifier. A multilevel computer processing program generates propagation statistics for attenuation as a function of rainfall rate, sky temperature, radar backscatter, and other meteorological variables. Downlink measurements made at the NASA Rosman, N. C. station typically show attenuations of 1 to 3 dB in light rains or dense fog; 3 to 7 dB in continuous rains (5 to 50 mm/h), and a number of fades exceeding 12 dB in heavy thunderstorms. Uplink fades of up to 18 dB in heavy rains have been observed. Correlation of measured attenuation with ground measured rainfall rate was low for a single gauge but improved significantly with height averaging of 10 gauges. Correlation of measured attenuation with sky temperature recorded on a small aperture radiometer was very good for most storms. Valid predictions of attenuation from 16-GHz sky temperature measurements were observed for up to 15 dB of measured attenuation. The uplink to downlink attenuation ratio varied with each precipitation event and often varied during a single storm. The ratio has ranged from 2:1 to 4:1 during heavy precipitation periods.