Beam-steering Surface Wave Fluid Antennas for MIMO Applications

This paper proposed to use surface wave fluid antennas to realize beam-steering functionality and spatial diversity for MIMO applications. By utilizing the advantage of the non-radiating feature of surface wave propagation, in contrast to the conventional multiple RF input ports approach reported, the proposed design only required one RF input to achieve the spatial diversity. The surface wave fluid antenna is designed to work in the millimeter-wave frequency band from 20 to 26.5 GHz. The preliminary results show that the radiation direction of the antenna can be controlled by changing the position of the fluid metal radiator

Radiation Pattern Diversified Single-Fluid-Channel Surface-Wave Antenna for Mobile Communications

In this paper, an antenna design that combines surface wave and fluidic reconflgurable techniques was presented. The antenna operates in a wide frequency range from 23 to 38 GHz, which covers the Very High 5G Frequency band in the US, Europe, China, Japan, and Korea. In this design, only one RF input port is needed to achieve diversity when compared with the conventional multiple RF input ports approaches. From the simulation results, the proposed antenna design could change its radiation pattern based on the position of the fluid radiator. Such radiation pattern diversity feature can deal with channel interference issues

Reconfigurable Surface Wave Fluid Antenna for Spatial MIMO Applications

This paper presents the design of a surface wave fluid antenna which can realizes beamshaping and spatial diversity for MIMO applications. The proposed design only required one RF input to achieve spatial diversity when comparing to the conventional multiple RF input ports approaches. The surface wave fluid antenna is designed for the millimeter-wave 5G mobile communications band from 24 to 28 GHz. The simulation results show that the radiation direction of the antenna can be controlled by changing the position of the fluid metal radiator

Radiation Pattern Diversified Double-Fluid-Channel Surface-Wave Antenna for Mobile Communications

In this paper, we present an antenna design for millimeter wave 5G applications. The proposed antenna has a wide working frequency range from 23.5 GHz to 36.5 GHz. This can cover the millimeter wave 5G frequency band in most countries. The design is simple and will mitigate the difficulty when implementing in a wireless system with reconfigurable capability. The antenna design only needs a single RF port as input to achieve radiation pattern diversity by moving the fluid radiators in its two channels. With the radiation pattern diversity capability, the problem like weak signal strength and inter channel interference can be eased.The design shows higher dynamic range of patterns turning when compare to the previous work on single-channel surface-wave antenna with the purpose of wider angular coverage with multichannel design. The comparison result of the two designs will also be provided in this paper

Effective throughput: A unified benchmark for pilot-aided OFDM/SDMA wireless communication systems

In this paper, we study the uplink performance of an orthogonal frequency division multiplexing (OFDM) wireless system where multiple antennas are utilized at the base station (BS). Further, capacity can be greatly enhanced through spatial division multiple access (SDMA), so that several users can transmit packets simultaneously to the BS. The system performance is determined by various transmission techniques, including methods for channel estimation, modulation, as well as channel coding. Conventional parameters such as packet error rate (PER) and bit error rate (BER) are unable to reflect the actual system performance because no consideration is given to the overheads incurred by the transmission techniques. Therefore, we are motivated to propose a novel concept called effective throughput to characterize the capacity available to users by incorporating all these factors. The effective throughput for a user can be viewed as the average number of successfully received data bits in an OFDM symbol after excluding erroneously received packets and the overheads due to channel estimation and coding. It also directly relates to the transmission delay of a user packet. The system effective throughput is the aggregated effective throughput of all users. Simulation results demonstrate that effective throughput can serve as a useful and more meaningful benchmark parameter in optimizing system performance.published_or_final_versio

Effective throughput for coded OFDM/SDMA systems with pilot-assisted channel estimation

This paper investigates the performance of coded orthogonal frequency division multiflexing (OFDM) systems with receiving adaptive array, through which multiple users with single-element transmitting antenna are supported simultaneously by spatial division multiple access (SDMA). We characterize the performance of an OFDM/SDMA systems by effective throughput, which is essentially the average number of data bits in an OFDM symbol after considering the erroneous packet transmissions and modulation scheme by excluding the overhead from coding and pilots for channel estimation. Optimization of system operating parameters can be achieved through the maximization of effective throughput. The focus of this paper is to study the impact of pilot density and the number of users on the performance of coded OFDM/SDMA systems. Through extensive computer simulation, we how that using more pilots always improves bit error rate (BER) performance, but may reduce effective throughput. The optimal number of pilots together with the modulation scheme can he determined by maximizing the effective throughput for given operating signal-to-noise ratio (SNR). It is also shown that the system performance degrades gradually with the increase of users. For a system with a six-element adaptive array, the effective throughput with 5 users is lower than that with 4 users for a certain range of SNR. This indicates that the maximal number of users supportable by the system should consider the effective throughput. © 2003 IEEE.published_or_final_versio

Toward Liquid Reconfigurable Antenna Arrays for Wireless Communications

Liquid-based antennas promise to overcome crucial limitations of traditional solid-based ones. Here, we describe different liquid antenna technologies that can be used to build arrays with the unprecedented flexibility and adaptivity needed to enable an evolution in wireless communications. We focus on two approaches that use either metallic or non-metallic liquids as radiating elements. In both cases, the resulting devices can be reconfigured dynamically, thus modifying the radiation parameters of an antenna in real time in an inexpensive way. To that end, we describe some of the challenges which arise when integrating such antennas as part of a whole communication system. We discuss the solutions adopted in some initial prototypes and summarize some of the problems that need to be solved to pave the way for integrating fully reconfigurable liquid antenna arrays in wireless communication systems

An Efficient Data Structure for Dynamic Two-Dimensional Reconfiguration

In the presence of dynamic insertions and deletions into a partially reconfigurable FPGA, fragmentation is unavoidable. This poses the challenge of developing efficient approaches to dynamic defragmentation and reallocation. One key aspect is to develop efficient algorithms and data structures that exploit the two-dimensional geometry of a chip, instead of just one. We propose a new method for this task, based on the fractal structure of a quadtree, which allows dynamic segmentation of the chip area, along with dynamically adjusting the necessary communication infrastructure. We describe a number of algorithmic aspects, and present different solutions. We also provide a number of basic simulations that indicate that the theoretical worst-case bound may be pessimistic.Comment: 11 pages, 12 figures; full version of extended abstract that appeared in ARCS 201

Use of functional MRI to evaluate correlation between acupoints and the somatic sensory cortex activities

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Design of superconducting MRI surface coil by using method of moment

A method of moment with an enhanced model to design high-temperature superconductor (HTS) RF surface coils for magnetic resonant image (MRI) is presented. The resonant frequency and quality factor (Q) of HTS RF spiral coils are simulated using this method. The agreements of resonant frequencies and Qs between the simulation and measurement are excellent with differences less than 1% and 3%, respectively. The 0.2-μ m-thick YBaCuO (YBCO) thin films are deposited onto single side of 0.508-mm-thick LaAlO 3 (LAO) and sapphire substrate and patterned into a spiral shape. To accurately analyze the resonant frequency and Q of a coil, an enhanced two-fluid model is employed. HTS RF coils with diameter of 65 mm for 0.2T and 1.5T MRI systems are designed and fabricated with the measured Q of 19 K and 23 K, respectively. In addition, the shift of resonant frequency due to the mutual coupling between two HTS spiral coils is predicted by this method, which is important for design of HTS coil arrays in an MRI system.published_or_final_versio