室内60 GHz毫米波无线信道参数及其相关性研究

基于典型的室内走廊环境,对60 GHz毫米波通信信道参数及其相关特性进行了研究.在视距和非视距条件下,分析了信道参数包括多径个数、均方根时延扩展、莱斯因子、阴影衰落的特点及其分布模型,研究了信道参数之间的相关特性.结果表明:在视距条件下各参数之间普遍具有较强的相关性,而在非视距条件下只有均方根时延扩展和多径个数之间的相关性较强.利用信道参数的相关特性可从一个参数来预测另一参数,为60 GHz无线通信系统的设计提供有用信息.     

FRAS: Fair Rate Adaptation Scheme for Directional Multicast in 60 GHz Multi-Gigabit WLANs

Although extensive studies have been carried out on the provision of multicast services in wireless local area networks (WLANs), most of them do not consider the use of directional antennas. In particular, rate adaptation and fairness issues among sectors in directional multicast are not well-studied topics. In this paper, a fair rate adaptation scheme (FRAS) that seeks to determine appropriate transmission rates that maintain fairness among sectors and accommodate as many multicast devices as possible is proposed. Extensive simulation results show that FRAS outperforms the equal-rate scheme in terms of the number of devices that receive multicast frames. Furthermore, FRAS can improve the fairness performance as compared with the heavy-sector first scheme.     

Application of fan-beam antennas for 60 GHz indoor wirelesscommunication

The application of fan-beam antennas in high-speed indoor wireless communication systems operating in the 60 GHz band is investigated. The effects of line-of-sight obstruction as well as antenna pointing deviation on the power link budget are experimentally studied in a typical laboratory environment. The results are contrasted with those obtained with alternative antenna configurations     

Comparative study of millimeter wave propagation at 30 GHz and 60 GHz in indoor environment

The millimeter wave band appears to be a favourable choice for personal wireless communication systems for indoor environment, as it meets the requirements for sufficient bandwidth, small terminal dimensions and sporadic usage for commercial applications. In this paper measurements of millimeter wave propagation in both 30 GHz and 60 GHz bands, are presented in a comparative way. The topology of measurements covers both a line-of-sight situation and also a case where a direct path between transmitter and receiver does not exist. Although the second case does not seem obvious for outdoor applications in these frequencies, in indoor environment the multipath signals produced by objects like walls, doors, furniture etc., can be utilised in order to overcome the man-made shadowing. Both slow and fast fading characteristics of the received signal are studied and the measurements are modelled by the conventional Rician and Rayleigh distributions. Both frequency bands offer advantages for usage in in-house wireless communication systems. Although in 30 GHz band the coverage area is bigger than in 60 GHz (with the same transmitting power), frequency reuse is easier in 60 GHz band. because even if millimeter waves ‘escape’ through ‘windows’, the specific attenuation due to atmospheric oxygen (15 dB/km) at 60 GHz eliminates the interference between communication channels in neighbouring buildings.     

Measurements and characterization of wideband indoor radio channel at 60 GHz

This paper presents the measurements, the statistical results and channel models extracted by impulse response measurements of an indoor 60 GHz radio channel. The measurements were based on the pulse sounding technique. Multipath parameters that characterize the channel have been extracted and analyzed statistically concerning corridors and offices locations. The mean excess delay is in the range of 3.84 to 8.18 ns for hallways and 3.52 to 14.69 ns for offices. Additionally, rms delay spread varies from 12.34 to 15.04 ns in corridors and from 12.56 to 21.09 ns inside the laboratory. The coherence bandwidth varies between 13.88 and 30.49 MHz in corridors with a mean value of 22.48 MHz. Inside offices the mean coherence bandwidth is 22.80 MHz for LoS locations and drops to 7.05 MHz for NLoS. Small-scale models for all the measured locations were developed using tapped delay lines. The maximum Doppler frequency of the modeled channel remains around 1 Hz, whereas the coherence time is calculated 1.04 s, which indicates that the channel remains, almost stationary, exhibiting very slow fading. Finally, from the models it is derived that the channel preserves WSS and US characteristics giving rise to a WSSUS representation.     

GHz programmable counter with low power consumption

A high-speed programmable counter with a new reloadable D flip-flop which integrates the programmable function to a true-single-phase-clock (TSPC) D flip-flop is presented. The proposed reloadable D flip-flop is able to operate at higher frequencies with lower power consumption compared to the performance of the existing bitcell. The programmable divide-by-N counter implemented with this reloadable D flip-flop using the Chartered 0.18 /spl mu/m CMOS process is capable of operating up to 2 GHz for a 1.8 V supply voltage with 4.7 mW power consumption.     

High-speed indoor wireless communications at 60 GHz with coded OFDM

A high-speed indoor wireless communication system using coded orthogonal frequency-division multiplexing (OFDM) and working at 60 GHz is proposed and analyzed. An actual propagation environment consisting of a medium sized research laboratory, characterized by means of a ray-tracing technique, is considered for the analysis. In this contest the paper investigates and discusses the effects of frequency diversity, antenna sectorization, OFDM clustering, and different block coding strategies. Moreover, to characterize the communication between stationary indoor terminals at millimeter waves, a new definition of coverage is introduced. In order to evaluate the performance of the coded system in the actual environment, a suitable semianalytical algorithm is defined and applied. In the results the feasibility of a coded OFDM system for 155 Mbit/s packet transmission is checked. It is shown that all the line-of-sight (LOS) positions and 70% of the no LOS points can be covered in the scenario considered with a transmitted power of 10 dBm     

Narrowband characterization of 60 GHz radio propagation in indoor environment

The increasing demand for high speed data and multimedia services forces indoor radio communications to exploit new, almost fully available bands. Among the possible radio spectrum parts, the 60 GHz band seems to provide a good solution to move on. Thus, the paper deals with mobile radio channel characterization in indoor environment at 60 GHz; this is accomplished by means of an electromagnetic computer model, based on a fully 3D ray tracing approach. The channel has been characterized both in terms of radio coverage and of radio signal statistics, evaluating the best fitting cumulative distributions, the relationship between their parameters and the corresponding environment characteristics and addressing the improvements achievable by means of space diversity techniques.     

Development of 60 GHz minimum delay spread indoor local area network

This paper describes the design, fabrication, and experimenting of an indoor millimeter-wave local area network system, operating in a new concept of the indoor propagation configuration named minimum delay spread configuration; brass-board models of 10, 100, and 155 Mbit/s transceivers operating at 60 GHz, and a 60 GHz mmic chip set installed in the brass-board models are also described.     

Effects of antenna directivity and polarization on indoor multipathpropagation characteristics at 60 GHz

In millimeter-wave indoor communications systems, the radiation patterns and polarizations of the antennas at base stations and remote terminals have a significant influence on channel characteristics. The work reported in this paper investigated the effects of the radiation patterns of the antennas at remote terminals on multipath propagation characteristics. These effects were investigated by indoor propagation measurements at 60 GHz conducted in a modern office room and by ray-tracing simulations based on geometrical optics. Multipath channel characteristics are compared in terms of impulse responses and their root-mean-square (rms) delay spreads for an omnidirectional antenna and for three directive antennas with different beam widths. From the results of measurements and ray-tracing simulations, the use of a directive antenna at the remote terminal is demonstrated to be an effective method of reducing the effects of multipath propagation. Further reduction in the multipath effects is found to be achieved by the use of circular polarization instead of linear polarization with the directive antennas     

SIMO channel performance evaluation on indoor environment at 2.4 GHz

This work presents an experimental study of single-input multiple-output (SIMO) channel performance in the indoor radio propagation environment. Indoor channel measurements at the 2.4-GHz ISM frequency band have been conducted using a versatile channel sounder test-bed platform. A single transmitting antenna, four receiving antennas with two proposed geometries and a four-branch receiver circuitry were used in order to achieve channel sounder measurements exploiting baseband signal-processing techniques. In-depth investigation of SIMO wireless channel performance was realised through three types of metrics: signal strength, gain coefficient and capacity. Performance results indicate SIMO channel capacity enhancement and illustrate differences between the two proposed geometries.     

Polarization dependence of multipath propagation and high-speedtransmission characteristics of indoor millimeter-wave channel at 60 GHz

Measurements of polarization dependence of multipath-propagation characteristics were conducted at 60 GHz in a room within a modern office building. Delay profiles were measured using a swept frequency method with a high time-delay resolution of 2 ns. Directions of arrival of the multipath components reflected from walls were analyzed by rotating a narrow-beam receiving antenna with an angular resolution of 5 degrees. Results of this experiment showed that multipath delayed waves due to wall reflection can be effectively suppressed by employing circular polarization instead of linear polarization. Based on this experimental result, a computer simulation was made to clarify the polarization dependence of the high-speed transmission characteristics of an indoor communications system operating at 60 GHz     

Comparison of theoretical and experimental 60 GHz silicon IMPATT diode performance

Theoretical and experimental investigations have been carried out for V-band (50-75 GHz) silicon double drift flat profile (DD) and double low high low (DLHL) IMPATT diodes. The theoretical designs have been used for the experimental realisation of the diodes for CW operation. The epitaxial layers were grown by silicon molecular beam epitaxy which enabled the realisation of the complex DLHL profile at millimetre-wave frequencies in the silicon material system for the first time. The maximum obtained conversion efficiency is 14.3%. A comparison of theoretical and experimental results for both types of diodes shows general agreement and the superiority of the DLHL structure.<>     

低功耗2.4GHz无线通信系统的设计与实现

低功耗、微型化是当前无线通信产品尤其是便携产品的迫切要求。本文提出了一种工作在2.4GHz ISM频段的无线传输系统的设计方案。该方案主要采用Nordic公司最新推出的射频芯片nRF24E1,设计并实现了一种近距离、低功耗的无线通信收/发系统。     

1 V 10 GHz CMOS frequency divider with low power consumption

A low supply voltage and low power ultra-high frequency divider is investigated. The proposed inverter of the frequency divider is able to operate at higher frequencies with enhanced output voltage swing and lower power consumption under an ultra-low supply voltage compared to that of existing divide-by-2 units. The frequency divider implemented with this inverter using the Chartered 0.18 /spl mu/m CMOS process is capable of operating up to 10 GHz for a 1 V supply voltage with 1.3 mW power consumption.     

Transposition of a baseband UWB signal at 60 GHz for high data rate indoor WLAN

The purpose of this letter is to demonstrate the high potentiality in terms of data rate and multiple access of a novel 60-GHz WLAN architecture for smart objects and indoor communication systems. This approach is based on the up-conversion of an ultrawide-bandwidth impulse radio signal (IR-UWB) in the 60-GHz frequency range to benefit of the natural advantages of the UWB technique while avoiding the baseband limitations. First results about the pulse generator and receiver architecture are discussed.     

室内6.05 GHz和2.45 GHz多输入多输出无线信道特性对比分析

为了明确高频段室内多输入多输出（Multiple-Input Multiple-Output,MIMO)无线信道与传统低频段的差异,采用基于矢量网络分析仪搭建的测量平台对典型室内环境下6.05 GHz频段和2.45 GHz频段MIMO无线信道进行测量和对比分析.基于300组高低频宽带MIMO信道测量数据,对比传输损耗、时延扩展、空间相关等大小尺度衰落特性.并阐明高频段无线空时信道新特性,分析新特性为系统设计带来的新问题.对比发现,6.05 GHz高频段与传统的2.45 GHz频段室内MIMO无线信道存在显著的差异.与2.45 GHz相比,6.05 GHz频段的传输损耗更大,时延扩展更严重,空间相关更低.在将低频段MIMO移动通信向高频段扩展时,这些差异要给予充分的重视.     

High-level capacity performance insights into wireless mesh networking

Despite the increasing interest in wireless mesh networking, it is still unclear how well these systems will scale with increasing user density. Therefore, the aim of this paper is to position mesh network performance within the context of the importance of the mesh-to-access link rate ratio and the number of radios per mesh node when operating the mesh under relatively high traffic loads.     

Linear dependence of double-directional spatial power spectra at 2.4 and 5.2 GHz from indoor MIMO channel measurements

Multiple-input multiple-output (MIMO) double-directional spatial channel responses for co-located indoor measurements at 2.4 and 5.2 GHz using eight element uniform circular arrays are compared. Correlation coefficients of the power spectra demonstrate a linear dependence, indicating similarity in propagation mechanisms at the two frequencies.     

Predicted HIPERLAN coverage and Outage performance at 5.2 and 17 GHz using indoor 3-D ray-tracing techniques

The European Telecommunications Standards Institute (ETSI) has recently defined a European standard for High Performance Radio LANs. This standard, known as HIPERLAN, has dedicated spectrum in both the 5 GHz and 17 GHz frequency bands. The system has been designed as an indoor wired-line replacement offering raw data rates in excess of 20 Mb/s.In this paper, simulated propagation data at 5.2 GHz and 17 GHz has been generated for a typical HIPERLAN environment. The analysis was performed using an indoor three dimensional ray-tracing algorithm developed for site specific single floor environments. The model is capable of predicting narrowband (power) and wideband (time dispersion) characteristics even in non-line-of-sight locations.Using this propagation information, the design of a suitable equaliser and the expected coverage of a HIPERLAN node is investigated for a particular indoor location. Emphasis has been placed on the need to develop low cost and robust receiver designs that are compatible with the design goal of a small and low power terminal.