Article

# Wideband MIMO Channel Sounder for Radio Measurements in the 60 GHz Band

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## Abstract

Applications of the unlicensed 60 GHz band include indoor wireless local area networks, outdoor short range communications and on body networks. To characterize the radio channel for such applications, a novel digital chirp sounder with programmable bandwidths up to 6 GHz with switched two transmit channels and two parallel receive channels for multiple-input multiple-output (MIMO) measurements was realized. For waveform durations of 819.2 μs, Doppler measurements can be performed up to 610 Hz for the single transmit and two receive configuration or 305 Hz for MIMO measurements. In this paper, we present the architecture of the sounder and demonstrate its performance from back to back tests and from measurements of rms delay spread, path loss and MIMO capacity in an indoor and an outdoor environment. For 20 dB threshold, the rms delay spread for 90% of the measured locations is estimated at 1.4 ns and 1 ns for the indoor and outdoor environments, respectively. MIMO capacity close to the iid channel capacity for 2 by 2 configuration is achieved in both environments.

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... Hence the angular spectrum and its temporal evolution are vital for the efficient design of NIST Sounder [28,29] Durham Sounder [30,31] Keysight [32,33] such systems [9]. ...
... The other state-of-the-art channel sounders are listed in Table 2 NIST Sounder [28,29] Durham Sounder [30,31] Keysight [32,33] chains. Similar to [30], the TX power is limited to 24 dBm. ...
... Although there has been increasing interest in the band between 6 GHz and 20 GHz [99], most of the measurement campaigns performed so far focus on bands below 6 GHz [44,[100][101][102][103] or above 20 GHz [4,13,22,27,28,31,104]. It is commonly accepted that the new mm-wave systems will have to coexist with the legacy networks (4G, LTE, WiFi etc.) operating mostly below 6 GHz. ...
... The present measurements were conducted using the custom-designed multi-band chirp (FMCW) channel sounder [8] in a seminar room and an office environment, shown in Fig. 1. The measurements were performed with a 6 GHz bandwidth in the frequency range of (59.6 -65.6 GHz) with a waveform repetition frequency of 1.22 kHz. ...
... Fig. 6 shows an example of the computed PAP in one location for the LoS and NLoS scenarios in the seminar room environment. The angular spread was estimated as outlined in [8][9], the 50% and 90% CDF values of the angular spread as well as the standard deviation are given in Table II. The table indicates that in both measured environments, the LoS locations exhibit a smaller angular spread value compared with NLoS locations due to less reflectors and scatterers. ...
... The FI model parameters including the distance coefficient (α) and the PL intercept coefficient (PLo) were estimated from the measurements. A detailed calculation of the FI model can be found in [8][9]. In the present work, the path loss was estimated for different possible antenna alignments. ...
Conference Paper
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The millimeter wave (mmWave) band around 60 GHz has been identified as one of the ISM bands for wireless indoor communication systems. In this paper, we present wideband channel measurements conducted at 60 GHz in a seminar room and office environment using state of art Durham University's channel sounder. The statistical channel parameters of power angle profile, root mean square delay spread, and angular spread are presented for different orientations which include line of sight, obstructed line of sight and non-line of sight with the smallest delay spreads and angular spreads values being observed for the line of sight case.
... 15.3c and IEEE 802.11ad standards are completed, and IEEE 802.11ay is being developed for next generation wireless fidelity (WiFi) around 60 GHz bands. Other frequency bands that have been widely investigated include 11,15,28,38,45, and 73 GHz bands. Various standardization organizations, international projects, and research groups such as 5GCM, 3GPP, METIS, MiWEBA, mmMAGIC, and NYU WIRE-LESS have aimed to propose channel models for 6-100 GHz [1,3]. ...
... Meanwhile, there are also some custom-designed frequency domain channel sounders. In [11], a digital frequency sweep channel sounder was designed and used a chirp signal as a sounding signal. The channel sounder was used to measure a 2 × 2 MIMO channel. ...
... One of the disadvantages of the RDA and UVA methods is that the channel should be kept static during channel measurements. In addition, some channel sounders also have the ability to measure MIMO channels with real antenna arrays working in switch or in parallel [11,12,15]. ...
Article
Millimeter wave (mmWave) communication is a key technology for fifth generation (5G) wireless communication systems due to its tremendous bandwidth available to support high data rate transmission. This article investigates the recent developments and future challenges in 5G mmWave channel sounders, measurements, and models. Various channel sounders are comprehensively classified and compared. Channel measurements in diverse indoor and outdoor scenarios for different mmWave bands are surveyed. Meanwhile, a comparison of multiple mmWave bands, validation of mmWave massive multiple-input multiple-output (MIMO) channel properties, and measurement and modeling of human blockage effects are shown. Different channel modeling approaches including deterministic, semi-deterministic, and stochastic modeling methods are summarized. Some future research directions are also given.
... The authors in [30,31] have proposed a sounder based on an array of directional horn antennas combined with fast switching at the receiver with a single transmit antenna. On the other hand, studies in [32,33] Nonetheless, the output transmit powers are limited to 16 dBm at 30 GHz, 7 dBm at 60 GHz and 4 dBm at 90 GHz, greatly reducing the dynamic range of the sounder. The authors in [34] present a sounder with 4 transmit antennas multiplexed with a single pole four throw (SP4T) switch and 4 receive antennas with 4 parallel down-conversion chains. ...
... GHz channel sounder capable of measuring 128×256 dual-polarized channels from the transmitter to the receiver. Our design facilitates measurements of an order-of-magnitude more channels with an equivalently higher angular resolution in comparison with other sounders presented in [3,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][38][39][40][41][42]. Our system is catered to extract dynamic directional behavior of channels with an overall field-ofview of 180 • at the transmitter and 360 • at the receiver. ...
... Before presenting the contributions of the paper, we make one further remark regarding the various channel sounding architectures seen in the literature. Rather interestingly, architectures based on switched arrays can be further classified into switched beam architectures (SBA), switched horn antenna arrays (SHA), and switched patch arrays (SPA), respectively [3,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][38][39][40][41][42]. The major difference between these approaches relates to the achievable dynamic range and scaliability of the design. ...
Preprint
A pre-requisite for the design of wireless systems is the understanding of the propagation channel. While a wealth of propagation knowledge exists for bands below 6 GHz, the same can not be said for bands approaching millimeter-wave frequencies. In this paper, we present the design, implementation and measurement-based verification of a re-configurable 27.5-29.5 GHz channel sounder for measuring dynamic directional channels. Based on the switched array principle, our design is capable of characterizing 128$\times$256 dual-polarized channels with snapshot times of around 600 ms. This is in sharp contrast to measurement times on the order of tens-of-minutes with rotating horn antenna sounders. Our design lends itself to high angular resolution at both link ends with calibrated antenna arrays sampled at 2$^\circ$ and 5$^\circ$ intervals in the azimuth and elevation domains. This is complemented with a bandwidth of up to 2 GHz, enabling nanosecond-level delay resolution. The short measurement times and stable radio frequency design facilitates real-time processing and averaging of the received wavefronts to gain measurement signal-to-noise ratio and dynamic range. After disclosing the sounder design and implementation, we demonstrate its capabilities by presenting dynamic and static measurements at 28 GHz over a 1 GHz bandwidth in an office corridor environment.
... In the literature, only a few mmWave channel sounders have the ability to measure MIMO channel in time-variant environments, such as the channel sounders from Durham University [19], National Institute of Standards and Technology (NIST) [20], [21], and University of South California [22]- [24]. In the following, related mmWave outdoor channel measurements with MIMO or V2V characteristics are reviewed. ...
... The CI model is P L(d, f )[dB] = 32.4 + 20log 10 (f ) + 10nlog 10 (d) + N (0, σ) (19) where n is the path loss exponent (PLE). The free space path loss at 1 m is used as the reference. ...
Preprint
Millimeter wave (mmWave) bands have been utilized for the fifth generation (5G) communication systems and will no doubt continue to be deployed for beyond 5G (B5G). However, the underlying channels are not fully investigated at multifrequency bands and in multi-scenarios by using the same channel sounder, especially for the outdoor, multiple-input multiple-output (MIMO), and vehicle-to-vehicle (V2V) conditions. In this paper, we conduct multi-frequency multi-scenario mmWave MIMO channel measurements with 4*4 antennas at 28, 32, and 39 GHz bands for three cases, i.e., the human body and vehicle blockage measurements, outdoor path loss measurements, and V2V measurements. The channel characteristics, including blockage effect, path loss and coverage range, and non-stationarity and spatial consistency, are thoroughly studied. The blockage model, path loss model, and time-varying channel model are proposed for mmWave MIMO channels. The channel measurement and modeling results will be of great importance for further mmWave communication system deployments in indoor hotspot, outdoor, and vehicular network scenarios for B5G.
... (Merwaday et al., 2014), (Le Naour et al., 2013), (Islam et al., 2013) have used USRP platform for creating channel sounding systems while (Thomä et al., 2001), (Kmec et al., 2005), (Kolmonen et al., 2010), (Maharaj et al., 2005), (Elofsson & Seimar, 2016) concentrate on channel sounder architectures for MIMO systems with (Elofsson & Seimar, 2016) using USRPs for channel sounder implementation. Some examples of channel measurements made using MIMO channel sounder can be seen in (Kim et al., 2015), (Liu et al., 2016), (Salous et al., 2016). (Salous et al., 2016) and (Panda et al., 2012) show the FPGA implementation of LFSR based PN sequences. ...
... Some examples of channel measurements made using MIMO channel sounder can be seen in (Kim et al., 2015), (Liu et al., 2016), (Salous et al., 2016). (Salous et al., 2016) and (Panda et al., 2012) show the FPGA implementation of LFSR based PN sequences. ...
Conference Paper
Full-text available
Implementation of an ultra wideband channel sounder in an FPGA of a Software Dfined Radio for measurement of Power Delay Profile.
... (Merwaday et al., 2014), (Le Naour et al., 2013), (Islam et al., 2013) have used USRP platform for creating channel sounding systems while (Thomä et al., 2001), (Kmec et al., 2005), (Kolmonen et al., 2010), (Maharaj et al., 2005), (Elofsson & Seimar, 2016) concentrate on channel sounder architectures for MIMO systems with (Elofsson & Seimar, 2016) using USRPs for channel sounder implementation. Some examples of channel measurements made using MIMO channel sounder can be seen in (Kim et al., 2015), (Liu et al., 2016), (Salous et al., 2016). (Salous et al., 2016) and (Panda et al., 2012) show the FPGA implementation of LFSR based PN sequences. ...
... Some examples of channel measurements made using MIMO channel sounder can be seen in (Kim et al., 2015), (Liu et al., 2016), (Salous et al., 2016). (Salous et al., 2016) and (Panda et al., 2012) show the FPGA implementation of LFSR based PN sequences. ...
Preprint
Full-text available
This paper concentrates on building a multi-antenna FPGA based Channel Sounder with single transmitter and multiple receivers to realize wireless propagation characteristics of an indoor environment. A DSSS signal (spread with a real maximum length PN sequence) is transmitted, which is correlated with the same PN sequence at each receiver to obtain the power delay profile . Multiple power delay profiles are averaged and the result is then sent to host. To utilize high bandwidth, the computationally expensive tasks related to generation and parallel correlation of PN sequences are moved to the FPGA present in each USRP (Universal Software Radio Peripheral). Channel sounder blocks were built using Vivado HLS and integrated with RFNoC (RF Network on Chip) framework, which were then used on USRP X310 devices.
... There have been several studies on the impact of rain attenuation on both satellite and terrestrial communication links. For satellite links, most of the beacon receivers are working at K-band (18)(19)(20)(21)(22)(23)(24)(25)(26)(27). In [3], rain attenuation over a four year period was measured at Ka-band (19.7 and 20.2 GHz) based on the ONERA satellite link. ...
... To study the impact of rain on fixed links, the customdesigned channel sounder reported in [22] is used. The sounder is upgraded with radio frequency (RF) heads at 12 MHz at the 77.52 GHz band which allows combining the received signals from the two bands for each polarization into a single channel of the data acquisition card, which is controlled for simultaneous automatic recording of data from the four receivers. ...
Article
Full-text available
Millimeter wave (mmWave) communication is a key technology for fifth generation (5G) and beyond communication networks. However, the communication quality of the radio link can be largely affected by rain attenuation, which should be carefully taken into consideration when calculating the link budget. In this paper, we present results of weather data collected with a PWS100 disdrometer and mmWave channel measurements at 25.84 GHz (K band) and 77.52 GHz (E band) using a custom-designed channel sounder. The rain statistics, including rain intensity, rain events, and rain drop size distribution (DSD) are investigated for one year. The rain attenuation is predicted using the DSD model with Mie scattering and from the model in ITU-R P.838-3. The distance factor in ITU-R P.530-17 is found to be inappropriate for a short-range link. The wet antenna effect is investigated and additional protection of the antenna radomes is demonstrated to reduce the wet antenna effect on the measured attenuation.
... A custom-designed frequency modulated continuous wave (FMCW) channel sounder developed at Durham University [7] was used to conduct LoS measurements in an indoor office environment shown in Fig. 1 (a), with the corresponding Tx and Rx locations in Fig. 1(b). The measurements were conducted with 6 GHz and 4.5 GHz bandwidth centered at 70 GHz and 38.5 GHz, respectively, at a repetition frequency of 1.22 kHz. ...
... The rms delay spread and the angular spread are estimated using equations 1 and 2 [7][8] ...
Conference Paper
Full-text available
This paper presents results of wideband channel measurements at 39 GHz and 70 GHz in a typical indoor office environment. Measurements were carried out using Durham University's multi-band frequency modulated continuous wave channel sounder. The propagation characteristics at different angular orientations are estimated and compared for both frequency bands. The effects of the antenna pattern on the propagation channel parameters such as the average power delay profile, root mean square delay spread, and angular spread, are analyzed. The results show similar propagation properties for both measured bands.
... In this paper, wideband indoor channel measurements where conducted in the 60 GHz ISM band in a meeting room, a classroom and a computer laboratory to measure and estimate different relative channel parameters. The measurements were performed using the multiband Frequency Modulated Continuous Wave (FMCW) channel sounder developed at Durham University [7]- [10]. ...
... Prior to extracting the relevant channel parameters, the noise floor is calculated in each PDP and a threshold is set above it in order to remove the noise samples from the PDP. The received power angle profile , at each azimuth angle , is shown in equation (2) as the sum of the corresponding noise free PDP [7]- [10]. (2) where is the excess delay of the tap delay and N is the number of delay bins in each PDP. ...
Conference Paper
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... An important sounding principle uses chirp signals, see [5], [6]. Sounding using chirps was disregarded for this work since multiple simultaneous Tx's are not supported with this principle. ...
Article
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Both massive multiple-input multiple-output (MIMO) technology and use of frequencies in the range 24-100 GHz are considered essential for upcoming 5G systems. Measurements of the new type of channels are needed, but this is challenging due to the large number of channels in massive MIMO and the short wavelength in the 24-100 GHz channels (so-called mmWave channels). This article describes a sounder system capable of measurements in both types of channels. While the same sounding system supports simultaneous massive MIMO and mmWave channels, the number of channels in each band and in total is in practice limited. For massive MIMO in the 300-6000 MHz band alone, arrays with up to 128 receiver (Rx) elements are possible, receiving from 16 independent mobile transmitter (Tx) antennas, where all channels are measured within 1.3 ms and in a 200 MHz bandwidth. To the authors knowledge, this is the first sounding system with this number of channels and a speed necessary for measuring the dynamic channels in typical application scenarios. For mmWave channels the sounder operates in the range 18-40 GHz. For these bands up to 2 Tx elements and 16 Rx elements can be measured. In addition, the paper describes some measurements in both a massive MIMO setup in an indoor sports arena and a mmWave setup with a handheld device containing a 7-element array.
... The custom-designed channel sounder [11] is used to conduct 26 GHz clutter loss measurements along three routes at Durham University, behind buildings indicated as (R1), (R2), and (R3), shown in Fig. 2(a)-(c). The Tx is located at a height of about 18.2 m with a down tilt angle of 12°, as shown in Fig. 2(d). ...
Conference Paper
Full-text available
Clutter loss refers to the power loss caused by clutter objects such as buildings and vegetation. The determination of clutter loss is crucial for the deployment of wireless communication networks. In this paper, we present results of clutter loss measurements at 26 GHz in a campus environment. The ITU-R P.2108-0 statistical clutter loss model is applied to model the clutter loss and the cumulative distribution functions (CDFs) of the measured and modeled clutter losses are compared, which show good agreement.
... While virtual arrays have flexible inter-element spacing and are immune to mutual coupling, the mechanical movement implies scan durations on the order of minutes or even hoursmuch longer than the channel coherence time (the time over which the channel can be considered static)and so are suitable for sounding static environments only. Millimeter-wave channel sounders that can deal with dynamic channels either feature a real array of horns that are switched electronically [14]- [16] or a real phased-array antenna that electronically steers beams [17]- [21]. They nevertheless can take up to seconds or even minutes for a complete angular scan depending on the angular resolution and scan range, whether the scan is spherical (in azimuth and elevation), and whether the scan is doubledirectional [22] (both at the transmitter (T) and receiver (R)). ...
Article
Full-text available
Millimeter-wave channel sounders are much more sensitive to phase drift than their microwave counterparts by virtue of shorter wavelength. This matters when coherently combining untethered channel measurements – scanned over multiple antennas either electronically or mechanically in seconds, minutes, or even hours – to obtain directional information. To eliminate phase drift, a synchronization cable between the transmitter and receiver is required, limiting deployment range and flexibility indoors, and precluding most outdoor and mobile scenarios. Instead, we propose a blind technique to calibrate for phase drift by post-processing the channel measurements; the technique is referred to as blind because it requires no reference signal and, as such, works even in non-line-of-sight conditions when the (reference) direct path goes undetected. To substantiate the technique, it was tested on real measurements collected with our 60 GHz virtual phased-array channel sounder, as well as through simulation. The technique was demonstrated robust enough to deal with the most severe case of phase drift (uniformly distributed phase) and in non-line-of-sight conditions.
... Moreover, a more compact and cost-effective V -band MIMO TX can be exploited by using the CMOS ADPLL technology instead of upconverter MIMO structures (either superheterodyne or direct conversion) [18], [37]- [40] and along with a 60-GHz frequency multiplier [41], where more complex hardware and costs are imposed. Additionally, further flexibility and reconfigurability are achievable with regard to the digitally intensive characteristics of the TX to fulfill a highly accurate digital beam-steering capability. ...
Article
A phase-coherent technique for multiple all-digital phase-locked loops (ADPLLs) is presented and developed in this paper to target a 57-63-GHz multiple-input multiple-output (MIMO) transmitter (TX) with a digital beam-steering capability. The ADPLL TX chains are first fabricated in nanoscale CMOS and then time-synchronized and frequency-phase locked by a field-programmable gate array (FPGA) evaluation board. The calibration approach for phase alignment is carried out using a cancellation method to acquire the out-of-phase state within two ADPLLs. The accuracy of beam steering and phase alignment is investigated and analyzed based on a time-domain model for ADPLL to consider the impact of phase noise. The analysis results offer the required values of the ADPLL parameters to allow a millimeter-wave (mm-wave) MIMO TX with a highly accurate digital beam-steering capability.
... channel is different at different frequencies, so the statistical models derived for sub-6 GHz bands may not be accurate for mmWave bands. Therefore, channel sounders operating at mmWave bands are required to characterize the nature of radio propagation at these frequencies [7]- [9]. ...
Preprint
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Millimeter-wave (mmWave) bands will be used for the fifth generation communication systems to support high data rates. For the proper characterization of the mmWave propagation channel, it is essential to measure the power angular-delay profile (PADP) of the channel which includes angle-of-departure (AoD) and angle-of-arrival (AoA) of the multipath components (MPCs). In this paper, we first describe in detail our 28 GHz channel sounder where directional horn antennas are placed on rotating gimbals. Then, for this specific sounder class, we describe and address the following two problems in extracting the MPCs from the measurements: 1) For the channel measurements at large distances between the transmitter (TX) and the receiver (RX), it is not possible to generate the triggering signal for the TX and the RX using a single clock (SICL). This necessitates the use of separate clocks (SECLs) which introduces a random timing drift between the clocks. 2) As the positions of the antennas change during the scanning process, total distance traveled by the same MPC differs at each measurement. These two errors together cause missing some of the MPCs and detecting MPCs that do not exist in reality. We propose an algorithm to correct the clock drift and the errors in the MPC delays due to the rotation of the antennas. We compare the MPCs from the SICL measurement and the corrected SECL measurements using a Hungarian algorithm based MPC matching method. We show that the percentage of the matched MPCs increases from 28.36% to 74.13% after the correction process.
... The CIR is then obtained from the channel frequency response by performing an inverse Fourier transform. However, swept frequency techniques of channel sounding usually suffer from slow measurement time which is undesirable in time variant channels [22,23]. In the literature, channel sounding in the frequency-domain is mainly performed using the vector network analyzer (VNA) which has less calibration and synchronization complexity as well lower hardware cost. ...
Article
Full-text available
In a wireless communication system, the radio propagation channel is a complicated component to characterise. Channel sounding equipment thus has to meet specific criteria to extract the desired channel parameters. In this study, the authors outline the development and validation of a vector network analyser (VNA) based channel sounder for the frequency range from 1 to 50 GHz using radio‐over‐fibre techniques. Three methods of de‐embedding phase errors due to hardware impairments are demonstrated and validated via back‐to‐back measurements. The bidirectional scheme utilising optical circulators is shown to have a superior performance over the two‐branch unidirectional and the two‐branch bidirectional schemes. Therefore, the bidirectional scheme utilising optical circulators is proposed to achieve a long‐range ultra‐channel sounder based on the VNA.
... The characterization of the wireless channel is different at different frequencies, so the statistical models derived for sub-6 GHz bands may not be accurate for mmWave bands. Therefore, channel sounders operating at mmWave bands are required to characterize the nature of radio propagation at these frequencies [7]- [10]. ...
Article
Full-text available
Proper characterization of the millimeter-wave (mmWave) propagation channel requires measuring the power angular-delay profile of the channel which includes angle-of-departure and angle-of-arrival of the multipath components (MPCs). In this paper, we first describe in detail our rotating directional antennas-based 28 GHz channel sounder. Then, for this specific sounder class, we describe and address the following two problems in extracting the MPCs from the measurements: 1) For long-distance channel measurements, triggering signal cannot be generated for the TX and the RX using a single clock (SICL). This necessitates the use of separate clocks (SECLs) which introduces a random timing drift between the clocks. 2) As positions of the antennas change during scanning, total distance traveled by the same MPC differs at each measurement. These problems together cause missing some of the MPCs and detecting MPCs that do not exist in reality. We propose an algorithm to correct the clock drift and MPC delay errors due to the rotation of the antennas. We compare the MPCs from the SICL measurement and the corrected SECL measurements using a Hungarian algorithm based MPC matching method. We show that the percentage of the matched MPCs increases from 28.36% to 74.13% after the correction process.
... GHz). The second sounder has additional upconverters to an intermediate frequency, IF, between 12.5-18 GHz with a maximum of 1.5 GHz bandwidth [5]. The IF signal is then up converted using frequency multipliers: x2 to generate a 3 GHz bandwidth in the frequency range 25-29 GHz, x3 to generate 4.5 GHz in the 36-41 GHz band, x4 to generate 6 GHz in the 50-75 GHz band and x6 to generate a maximum of 9 GHz in the 60-90 GHz band. ...
Conference Paper
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This paper presents results of path loss measurements, in two indoor environments for both LoS and NLoS scenarios across a frequency range from 0.6-73 GHz using the multi-band custom designed channel sounders developed at Durham University. The data are analysed to estimate the path loss parameters for each frequency band with either the close in path loss model which assumes free space loss at 1 m reference distance and the floating intercept path loss model which estimates both parameters of the path loss model. The data across the multiple bands are then combined to generate a single set of coefficients for a frequency dependent path loss model. The median and 90% values of the rms delay spread values for a 20 dB threshold are presented across the frequency range of 0.6-39 GHz.
... It can solve the problems of higher bandwidth and mitigates the atmospheric impairments that cause the signals to be degraded. Different frequency bands in millimetre waves like 28 GHz, 38 GHz and 60 GHz are exploited and wireless channel modelling is performed [4][5][6]. Whereas, the millimetre waves in the range of 71 GHz to 81 GHz frequencies are also under consideration for wireless channel modelling. It is quite tedious and difficult to perform channel modelling at mm-wave because of their vulnerability in the atmosphere [7]. ...
Article
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To meet the demand of high spectrum requirement and high-speed wireless communication in future, millimetre waves (mm-Wave) can play a very important role for it. Millimetre waves starting from 30 GHz and ending at 300 GHz can solve the problems like high throughput, faster data rates and capacity. Millimetre waves can help to achieve higher gain by using high dimensional antenna array technology. Beamforming and spatial multiplexing are very famous techniques that can help to increase the gain when antenna arrays are used. Channel modelling plays a very important role in determining the possibility of deploying the wireless communication system. In this research paper, the major challenges regarding the mm-Wave channel modelling are identified and the statistical behaviour of mm-Wave channel at 28GHz and 73 GHz is explained with the help of NYUSIM software. The power loss, power delay profile and path loss, angle of arrival and departure are simulated in this work. These simulations are performed using multiple antennas configuration along with considering the effect of atmospheric impairments like rain, humidity and temperature.
... Pulse compression-based sounders, which rely on chirp pulses to achieve bandwidth compression at baseband, may achieve faster probing rates [19]. 6. ...
Article
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The increasing bandwidths and frequencies proposed for new mobile communications give rise to new challenges for system designers. Channel sounding and channel characterization are important tasks to provide useful information for the design of systems, protocols, and techniques to fight the propagation impairments. In this paper, we present a novel radio channel sounder capable of dealing with non-stationary channels. It can be operated in real-time and has a compact size to ease transport. For versatility and cost purposes, the core of the system is implemented in Field Programmable Gate Arrays (FPGAs). Three measurement campaigns have been conducted to illustrate the performance of the sounder in both static and non-static channels. In its current configuration, the sounder reaches an RF null-to-null bandwidth of 1 GHz, providing a delay resolution of 2 ns, a maximum measurable Doppler shift of 7.63 kHz, and 4.29 s of continuous acquisition time. A comparison with other channel sounders in the literature reveals that our proposal achieves a good combination of performance, cost, and size.
... Mm-Wave radio propagation characteristics differ from channels with sub-6 GHz bands in terms of high path loss, high delay resolution, and blockage caused by humans crossing the line of sight [4]. Therefore, a number of channel models for mm-Wave bands between 6 and 100 GHz have been investigated and developed for various scenarios, such as outdoor [5]- [7], indoor [8]- [11], and vehicle-to-vehicle [12], [13]. ...
Article
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This paper proposes a new non-stationary three-dimensional (3D) channel model for a physical millimeter wave (mm-Wave) multiple-input multiple-output (MIMO) channel. This MIMO channel model is driven by the trajectory of a moving point scatterer, which allows us to investigate the impact of a single moving point scatterer on the propagation characteristics in an indoor environment. Starting from the time-variant (TV) channel transfer function, the temporal behavior of the proposed non-stationary channel model has been analyzed by studying the TV micro-Doppler characteristics and the TV mean Doppler shift. The proposed channel model has been validated by measurements performed in an indoor environment using a MIMO radar kit operating at 24 GHz. For the measurement campaign, we used a single swinging pendulum as a model for a moving point scatterer. The trajectory of the pendulum has been captured by an inertial measurement unit attached to the pendulum and by a motion capture camera system. The measured trajectories are feed into the proposed mm-Wave MIMO channel model. The results obtained for the micro-Doppler characteristics show an excellent agreement between the proposed MIMO channel model and real-world measured channels in the presence of a moving point scatterer. We believe that our model can serve as a basis for the development of novel non-stationary MIMO channel models capturing the effects caused by moving objects and people.
... The measurements were performed using the chirp or frequency-modulated continuous wave (FMCW) channel sounder, developed at Durham University, [1] with new RF heads operating in the 24.5-30 GHz band with a maximum bandwidth of 3 GHz. ...
Conference Paper
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This paper presents the results of parameter measurements in two indoor environments for both line of sight (LoS) and non-line of sight (NLoS) scenarios at 25 GHz using multiple directional antennae at the transmitter and a single omnidirectional antenna at the receiver (MISO) with the custom-designed channel sounder developed at Durham University. The data are analysed to estimate the K-factor, path loss parameters and root mean square (RMS) delay spread for each scenario. The 50% and 90% values of the RMS delay spread values for a 20 dB threshold are presented for both scenarios.
... [5] or [6], describe various multiple-input multiple-output time domain channel sounding systems with a bandwidth of several GHz and a reasonable dynamic range of 30-50 dB. In [7], a channel sounding system with similar parameters, but utilising frequency swept (chirp) waveform, is demonstrated. ...
Article
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This study describes a time domain channel sounder based on binary sequences. The channel sounder system consists of several off-the-shelf laboratory instruments and is controlled by a PC. The frequency band of interest is the unlicensed millimetre wave band, 57-64 GHz. A crucial feature of the proposed system is its fast measurement speed enabling measurements of realistic vehicular scenarios. The main part of the study is dedicated to the description and analysis of the system behaviour when nonlinear components, such as mixers, low noise amplifiers or power amplifiers are used. The contributions of this study are the description of how to mitigate these effects utilising several different excitation signals and the evaluation and comparison of the channel sounder performance in terms of the spurious-free dynamic range parameter.
... A wideband digital sweep 2x2 MIMO channel sounder at 60 GHz with 6 GHz bandwidth is presented in [167]. It gives an interesting overview of channel measurements and models in the mmW band. ...
Thesis
With the development of digital technology and the Internet of Things, there is a growing need for transmission rates per user, capacity, security and flexibility of communications systems. This trend isgeneral in all areas of society and particularly in the field of transport. The digitization of services and autonomous and connected mobility require the development of V2X (vehicles for all) communication systems offering increasingly high transmission speeds, capacity and a level of security. Fifth generation (5G) cellular networks promise significant improvements in throughput, capacity, latency and reliability. Thus, thanks to the possibilities of this technology and due to the obsolescence of the current ground-train communication system used in Europe, GSM-R (Global System for Mobile Communication - Railway) will be replaced by FRMCS (Future Railway Communication System). ) which provides for the parallel use of several radio access techniques including 5G. This 5G technology will allow the emergence of new services: remote driving of trains without a driver on board, deployment of automated trains, coupling / decoupling of line trains, etc. Thus, 5G paves the way for the rail networks of the future that are more connected, more automated and, therefore, more available, safer and more respectful of the environment.The development of these new services requires guaranteeing the robustness, reliability and operational safety of the wireless links on which they are based. To do this, it is necessary to be able to assess the various communication systems upstream of their deployment in railway environments representative of those encountered along railways (trenches, urban areas, rural areas, stations, yard areas, tunnels, etc. .) by emulating these environments in channel emulators using channel templates. Representative channel models are obtained with measurements or simulations (Ray tracing/launching).Thus, this thesis work focuses on the implementation of a 4 x 4 MIMO (Multiple-input, Multiple-output) channel sounder in the 1-6 GHz range in order to characterize different railway environments for which models do not exist. not yet. The equipment developed is based on the use of software radio cards and specific software that have been modified. It is a two-part LTE (Long Term Evolution) type telecommunications system: a base station that will be installed alongside the infrastructure, and a mobile station on the train. The radio channel characteristics are measured by calculating the channel estimate via the pilots of an LTE-OFDM symbol. It can be used on the move. The assembly is compact enough to be transported and allow measurements of the channel in any type of environment.In this thesis we describe the different channel models in the literature and we analyze the existing models in the railway sector in order to identify the environments where it will be necessary to carry out measurements. We focus on simple Tapped Delay Line –TDL models. Secondly, we provide a state of the art of the different types of channel sounder and radio channel sounding techniques. This work allowed us to choose the sounder technology developed, namely a system based on the use of reconfigurable SDR (Software Defined Radio) cards and an LTE type signal. We then detail the architecture, principle and implementation of the channel sounder and its validation by simple measurements. This part constitutes the heart of the thesis. Finally, the last chapter is devoted to field measurements. We conclude and give very many perspectives of the work.
... The FMCW sounder described in (Salous et al., 2016) was upgraded in order to cover additional frequency bands as identified by WRC15. This was achieved by a programmable local oscillator (ADF5355) as shown in Figure 8 to up convert the Intermediate Frequency (IF) signal in the 2.2-2.9 ...
Article
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The International Telecommunications Union Radiocommunication Sector (ITU‐R) Study Group 3 identified the need for a number of radio channel models in anticipation of the World Radiocommunications Conference in 2019 when the frequency allocation for 5G will be discussed. In response to the call for propagation path loss models, members of the study group carried out measurements in the frequency bands between 0.8 GHz up to 73 GHz in urban low rise and urban high rise as well as suburban environments. The data were subsequently merged to generate site general path loss models. The paper presents an overview of the radio channel measurements, the measured environments, the data analysis and the approach for the derivation of the path loss model adopted in Recommendation ITU‐R P.1411‐10.
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We developed a portable and traceable artifact for the conducted verification of millimeter-wave-frequency channel sounders under static conditions. The artifact is designed to create several multipath profiles with a direct path and up to two multipath components to be used during the verification of a channel sounder. The verification artifact shows that the channel sounder we tested measures extra multipath components possibly due to internal reflections in the channel sounder. While these differences are not likely to significantly change most channel metrics, they do indicate nonidealities in the channel sounder that might need to be addressed, depending on the application.
Article
In this paper, a millimeter-wave (mm-W)–multiple-input multiple-output (MIMO) channel model is introduced for the fifth-generation (5G) of microcellular communication systems. This deterministic channel model is based on reflection phenomena, which is a dominated propagation mechanism at mm-W communication systems. The model analyzes the channel capacity (CP) based on some important factors including frequency, absorption atmosphere, polarization, materials of surfaces and distance between the transmitter and the receiver. Four urban scenarios are considered in the analyses which are based on real urban constructions. Finally, Measurement data that have been conducted on the other work validate the theoretical analysis and demonstrate that the proposed model can be used to predict CP in urban areas for 5G systems.
Article
This paper presents system design, calibration and example measurements of a novel ultra-wideband, low-cost, realtime channel sounder. The channel sounder operates in the frequency range from 3 GHz to 18 GHz with a 15 GHz bandwidth thus providing a Fourier delay resolution of 66.7 ps. It sequentially measures overlapping sub-bands of 1 GHz bandwidth to cover the whole frequency range. By using a waveform generator and a digitizer with relatively lower sample rates, the design significantly lowers the cost compared to sampling the whole band simultaneously. With the transmitting power of 40 dBm, the maximum measurable path loss is 132 dB without accounting for possible antenna gains. In this work, we also describe the calibration procedure along with the method to stitch sub-bands into a combined channel response across 15 GHz of bandwidth. The channel sounder performance is compared with vector network analyzer (VNA) measurements acquired in the same static channels. In contrast to VNAs, however, our channel sounder can measure the whole band in 6 ms and can thus operate in dynamic environments with coherence time more than 6 ms. Additionally, we present sample results from a measurement campaign performed in an indoor corridor investigating the delay spreads statistics over the range of 3- 18 GHz.
Article
We describe a 60-GHz channel sounder with phased-array antennas and 1-GHz bandwidth. It estimates the angle of departure (AoD)/angle of arrival (AoA) of channel multipath components (MPCs) by sweeping the antenna space of the transmitter/receiver through 5.6° electronically steerable beams. The associated 26.1-dBi gain and resultant 36-dBm EIRP of the beams enable sounding up to hundreds of meters. Both ends integrate multiple arrays to extend the ±45° field of view (FoV) of the individual arrays to an omnidirectional view; the additional advantage of integrating multiple arrays is to quicken the channel sweep period to just $262~ {\mu s}$ , corresponding to a maximum closing velocity of 33 km/h for vehicle-to-vehicle (V2V) scenarios. The receiver is mounted on a mobile robot whose navigational system enables rapid, autonomous, and untethered data collection. Over-the-air (OTA) methods to characterize the array beams patterns, calibrate the system impulse response, and compensate for clock drift are proposed such that properties of the MPCs can be extracted with high fidelity through super-resolution techniques. To substantiate the latter, we compare estimated properties against ground-truth values from extensive field measurements. The mean absolute error in angle was reported as 2.87°.
Article
In this paper, we present a novel real-time multiple-input-multiple-output (MIMO) channel sounder for the 28 GHz band. Until now, most investigations of the directional characteristics of millimeter-wave channels have used mechanically rotating horn antennas. In contrast, the sounder presented here is based on a phased array structure that performs fast electronic steering of the beams in the horizontal and vertical domain. This approach drastically shortens the measurement times for measurements that are directionally resolved both at the transmitter (TX) and the receiver (RX), measurement time per location is reduced from minutes or hours to milliseconds. This not only enables measurement of more TX-RX locations for a better statistical validity but also allows to perform directional analysis in dynamic environments. The sounder also has high phase stability, which, in conjunction with the short measurement time, leads to a low phase drift between TX and RX. This in turn enables phase-coherent sounding of all beam pairs even when TX and RX have no cabled connection for synchronization, and thus avoids any delay ambiguity. Furthermore, the phase stability over time enables complex RX waveform averaging to improve the signal to noise ratio during high path loss measurements. The paper discusses both the system design as well as the measurements performed for verification of the sounder performance. Furthermore, we present sample results from double directional measurements in dynamic environments.
Thesis
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Article
Human blockage and its dynamics are potential challenges for millimeter-wave (mm-wave) mobile communication. This article presents the results of wideband measurements at 27 GHz with one human blocker close by a dynamic mobile terminal (MT) as well as one or multiple dynamic human blockers further away from an MT. The measured human blockage loss is largest when the direct path (DP) in a line-of-sight (LOS) is blocked, but this loss is limited by other multipath components (MPCs). For nonline-of-sight (NLOS) channels, it is shown that human blockage loss is typically negligible. The presented measurement results show that human blockage loss in multipath channels is much smaller than that reported in diffraction- and measurement-based models, which neglect or minimize the contribution of all MPCs other than the DP. This suggests that the multipath nature of the indoor wireless channel highly limits the impact of human blockage.
Thesis
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Millimetre wave (mmWave) wireless communication is one of the most promising technologies for the fifth generation (5G) wireless communication networks and beyond. The very broad bandwidth and directional propagation are the two features of mmWave channels. In order to develop the channel models properly reflecting the characteristics of mmWave channels, the in-depth studies of mmWave channels addressing those two features are required. In this thesis, three mmWave channel models and one beam alignment scheme are proposed related to those two features. First, for studying the very broad bandwidth feature of mmWave channels, we introduce an averaged power delay profile (APDP) method to estimate the frequency stationarity regions (FSRs) of channels. The frequency non-stationary (FnS) properties of channels are found in the data analysis. A FnS model is proposed to model the FnS channels in both the sub-6 GHz and mmWave frequency bands and cluster evolution in the frequency domain is utilised in the implementation of FnS model. Second, for studying the directional propagation feature of mmWave channels, we develop an angular APDP (A-APDP) method to study the planar angular stationarity regions (ASRs) of directional channels (DCs). Three typical directional channel impulse responses (D-CIRs) are found in the data analysis and light-of-sight (LOS), non-LOS (NLOS), and outage classes are used to classify those DCs. A modified Saleh-Valenzuela (SV) model is proposed to model the DCs. The angular domain cluster evolution is utilised to ensure the consistency of DCs. Third, we further extend the A-APDP method to study the spherical-ASRs of DCs. We model the directional mmWave channels by three-state Markov chain that consists of LOS, NLOS, and outage states and we use stationary model, non-stationary model, and null'' to describe the channels in each Markov state according to the estimated ASRs. Then, we propose to use joint channel models to simulate the instantaneous directional mmWave channels based on the limiting distribution of Markov chain. Finally, the directional propagated mmWave channels when the Tx and Rx in motion is addressed. A double Gaussian beams (DGBs) scheme for mobile-to-mobile (M2M) mmWave communications is proposed. The connection ratios of directional mmWave channels in each Markov state are studied.
Article
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Untethered channel sounders are used to measure mobile radio propagation channels. As high data rate, millimeter-wave and multiple-input multiple output (MIMO) are considered in the next generation communications systems, knowledge of the propagation channel needs to be studied in high accuracy. Measuring time stability of the clocks in both transmitter and receiver is essential when characterizing relative delay between multipath components (MPCs), absolute delay, angle of arrival (AoA) and angle of departure (AoD) of MPCs. This paper describes timing circuit design of untethered electronic switched MIMO millimeter-wave channel sounders, proposes practical method to remove a constant initial time error, and experimentally estimates time stability of the channel sounders. Time stability is classified in three categories: short-term (in order of microseconds) that impacts relative delay, AoA and AoD; medium-term (in order of minutes) that impacts absolute delay; and long-term stability (in order of days) that can be calibrated. This is the first time to apply standard parameters for measuring clock stability, such as timing Allan deviation (TDEV) and time interval error (TIE), to channel sounding and modeling. Novel methods are developed for measuring jitter and short-term noise. It was found that TDEV for short-term measurements was less than 1 ps and the medium-term timing errors due to clock noise could be maintained at 0.4 ns/min.
Article
Millimeter wave (mmWave) bands have been utilized for the fifth generation (5G) communication systems and will no doubt continue to be deployed for beyond 5G (B5G). However, the underlying channels are not fully investigated at multi-frequency bands and in multi-scenarios by using the same channel sounder, especially for the outdoor, multiple-input multiple-output (MIMO), and vehicle-to-vehicle (V2V) conditions. In this paper, we conduct multi-frequency multi-scenario mmWave MIMO channel measurements with 4×4 antennas at 28, 32, and 39 GHz bands for three cases, i.e., the human body and vehicle blockage measurements, outdoor path loss measurements, and V2V measurements. The channel characteristics, including blockage effect, path loss and coverage range, and non-stationarity and spatial consistency, are thoroughly studied. The blockage model, path loss model, and time-varying channel model are proposed for mmWave MIMO channels. The channel measurement and modeling results will be of great importance for further mmWave communication system deployments in indoor hotspot, outdoor, and vehicular network scenarios for B5G.
Article
In this paper, a calibration of multiple-input multiple-output (MIMO) channel sounders with internal crosstalk is considered. The objective is to minimize the number of back-to-back (B2B) connections required to estimate the transmitter (Tx) and receiver (Rx) response matrices that convey the information about linear distortion and internal crosstalk. A signal and system model is developed for the B2B measurements, where only some pairs of the Tx and Rx ports of the sounder are utilized among all pairs of the ports. Using the measurement model, a least-square estimation problem is then formulated and converted in the frequency domain to weighted rank-one approximation problems. The notion of system identifiability of a MIMO channel sounder is introduced and some optimal sets of B2B connections are proposed. Given a proposed optimal set of B2B connections, the alternate convex search (ACS) algorithm with a proper initialization is also proposed to solve the weighted rank-one approximation problems. Finally, it is shown how to calibrate field measurement data by using the estimated response matrices. Numerical results show that, only after a couple of iterations, the ACS algorithm with the proposed initialization achieves a comparable identification and calibration performance to the conventional method that requires the B2B connections of all port pairs.
Article
Development of a comprehensive channel propagation model for high-fidelity design and deployment of wireless communication networks necessitates an exhaustive measurement campaign in a variety of operating environments and with different configuration settings. As the campaign is time-consuming and expensive, the effort is typically shared by multiple organizations, inevitably with their own channelsounder architectures and processing methods. Without proper benchmarking, it cannot be discerned whether observed differences in the measurements are actually due to the varying environments or to discrepancies between the channel sounders themselves. The simplest approach for benchmarking is to transport participant channel sounders to a common environment, collect data, and compare results. Because this is rarely feasible, this paper proposes an alternative methodology – which is both practical and reliable – based on a mathematical system model to represent the channel sounder. The model parameters correspond to the hardware features specific to each system, characterized through precision, in situ calibration to ensure accurate representation; to ensure fair comparison, the model is applied to a ground-truth channel response that is identical for all systems. Five worldwide organizations participated in the cross-validation of their systems through the proposed methodology. Channel sounder descriptions, calibration procedures, and processing methods are provided for each organization as well as results and comparisons for 20 ground-truth channel responses.
Conference Paper
Ray launching (RL) algorithms are widely employed in indoor radio frequency (RF) design and planning, where a trade-off exists between the prediction accuracy and the computational cost. In this paper, a RL-based channel simulation is carried out in a simplified three-dimensional (3D) model of a typical classroom environment at the Ka-band. Channel measurements are conducted in a practical scenario to verify the accuracy of the simulations. The path loss and root mean square (RMS) delay spread of the propagation channel obtained from simulations and measurements are reported and compared, which show good agreements.
Chapter
In this paper, we proposed a novel MIMO channel measurement system architecture for 5G wireless communication based on the delay lines in combination with switches, and we implement propagation graph modeling to simulate the channel measurement procedure. Channel sounders equipped with multiple-element antenna arrays in the transmitter (Tx) and receiver (Rx) usually perform a measurement in two ways: switched channel measurement and parallel channel measurement. The latter usually needs multiple Txs/Rxs which leads a high cost, while the former with a high-speed radio-frequency switch at the transmitter and receiver has a lower cost but it is difficult to realize beamforming due to the Tx/Rx antennas do not transmit/receive signals simultaneously. By adding delay lines to the switched MIMO channel measurement system, the delay in different time slot at every Tx antennas can be compensated so that the multiple Tx antennas (empowered by only one Tx) transmit signals simultaneously. Furthermore, adding phase shifters after delay lines makes it easy to change the phase of each signal, which provides a convenient way for beamforming. The feasibility of the proposed method is preliminarily validated through simulations based on propagation graph modeling, the evaluation of the results is conducted by calculating the channel impulse response (CIR) or power delay profile (PDP) and estimating the direction of arrival (DOA) using Multiple Signal Classification (MUSIC) algorithm.
Article
We describe a mathematical framework for evaluating timing offset and timing noise in channel sounders based on a second-order deterministic model and a stochastic metric based on the Allan Deviation. Using this framework, we analyze the timing offset and noise for a 1-6 GHz correlation-based channel sounder that uses rubidium clocks to provide a common timebase between the transmitter and receiver. We study timing behavior in three clock-distribution configurations. In the “untethered” configuration, the transmitter and receiver each have a rubidium clock, and no physical timing cable is connected between the clocks. In the “tethered” configuration, a coaxial cable synchronizes timing between the two separate clocks. Finally, a benchmark “single-clock” configuration is used where a single rubidium clock drives the transmitter and receiver.
Article
A new comparison-to-reference performance verification technique compares an ${E}$ -band channel-sounder (CS) and reference vector network analyzer (VNA) measurements of the same controlled, static channel. This new technique reduces the number of inaccurate assumptions that exist in other methods providing a stronger verification of the CS hardware and processing performance. This technique compares the CS and VNA-derived channel metrics from these measurements. Using mechanical switches, we established a controlled, static RF channel. The VNA has a comprehensive uncertainty analysis that propagates systematic and random uncertainties through to the power delay profiles. The method is suitable for millimeter-wave CS hardware with removable antennas.
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This paper presents the verification of indoor propagation channel simulations based on an intelligent ray launching algorithm (IRLA) in the Ka-band of the millimeter-wave (mmWave) spectrum in various indoor environments, including a classroom, an office, and a corridor, by radio channel measurements. Power delay profiles (PDPs), path loss, and root-mean-square (RMS) delay spreads were obtained from both the simulation results and the measurement results. Moreover, parameters of two site-general path loss models, the close-in free space reference distance path loss model and the floating-intercept path loss model, were estimated based on the measured and simulated path loss. The comparison between the simulation results and the measurement results indicates that the IRLA-based simulation can accurately describe the main characteristics of the indoor propagation channel in the Ka-band.
Chapter
This article provides an overview of measurements and models of millimeter-wave (mmWave) propagation channels. After a review of the frequency dependence of propagation phenomena and the definition of parameters of interest, we then discuss the different methods for measuring mmWave channels both indoors and outdoors. Then follows an overview of the key measurement results, surveying again the literature of indoor channels, outdoor channels, and the impact of moving people. A survey of different types of channel models, including 3GPP type, geometry-based stochastic channel models, and map-based models elucidates the aspects of those models that are particularly relevant for mmWave frequencies. A discussion of the interaction of channels and mmWave systems and an outlook and discussion of future research topics round off this article.
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This paper presents a millimeter-wave propagation-channel sounder that uses an optical-fiber cable to achieve phase coherence between transmitting and receiving antennas using two modulated light waves in the vicinity of 1550 nm. In the described sounder, the optical-fiber cable approach permits a separation of up to almost 1000 m between the transmitter and receiver because of the low level of attenuation per unit length in a single-mode optical-fiber cable. The measurement system can sweep from 500 MHz below 60.1 GHz (59.6 GHz) to 500 MHz above 60.1 GHz (60.6 GHz) and proceed to 10 001 in-phase and in-quadrature propagation channel measurements in ${sim}{rm 5}~{rm sec.}$ Measurements of the frequency response of nonline-of-sight and line-of-sight indoor/outdoor propagation channels over medium $({>}{rm 100}~{rm m})$ and short ranges can be performed for two or more different lateral receiving antenna positions for antenna diversity studies.
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Conference Paper
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In this paper, we introduce a modular channel sounder setup based on laboratory components. The time-domain system covers a bandwidth of 1 GHz. With respect to subsequently presented measurement results, the utilization of the setup for measurements in the millimeter wave band is described. However, in principle, the concept can be adapted to any frequency band. Fundamental aspects concerning the choice of the sounding sequence are discussed. To validate the practical functionality of the setup, we present exemplary measurement results for the short range 60 GHz in-cabin channel.
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This paper contains measured data and empirical models for 2.5 and 60 GHz in-building propagation path loss and multipath delay spread. Path loss measurements were recorded using a broadband sliding correlator channel sounder which recorded over 39000 power delay profiles (PDPs) in 22 separate locations in a modern office building. Transmitters and receivers were separated by distances ranging from 3.5 to 27.4 m and were separated by a variety of obstructions, in order to create realistic environments for future single-cell-per-room wireless networks. Path loss data is coupled with site-specific information to provide insight into channel characteristics. These measurements and models may aid in the development of future in-building wireless networks in the unlicensed 2.4 and 60 GHz bands.
Article
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Nowadays, the need for high-data-rate-communication channels is increasing and will ineluctably continue to increase in the future. From a theoretical point of view, the multiple input multiple output (MIMO) approach seems to be one of the best solutions to provide such a high capacity. This paper presents a millimeter-wave MIMO channel measurement system developed in the Radio Laboratory of Helsinki University of Technology. The system is based on a sounder and virtual antenna arrays: The antenna arrays are obtained by two 2-D scanners which shift a single transmit antenna and a single receive antenna. Measurements in line of sight (LOS) and non-LOS are reported from what the MIMO channel capacity is calculated for various antenna array sizes. Furthermore, from the same measurements, the direction of departure and direction of arrival are estimated
Conference Paper
Propagation between two antennas on a human body in millimeter-wave frequency band have been investigated empirically. Propagation characteristics of a number of on-body propagation channels were studied with two types of antennas: quarter-wavelength monopoles and rectangular horns, the first being representative of low-gain omnidirectional antennas and the latter being the high-gain directional antenna. The channel characteristics for the two types of the antennas were compared. The path gain of the links with the horn antennas was found to be higher the that for monopoles. However, the variability of the path gain was also much greater for some channels. The path gain variation with time was described by a two-scale statistical model in which short-term fading was found to follow approximately Cauchy-Lorentz probability distribution.
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Radio channel models for 60 GHz very-high-speed radio systems in hospital environments are presented. Two possible applications of those systems have been considered: real-time video streaming for angiography and ultrasonic imaging. Channel modeling was performed for delay domain multipath characteristics based on extensive radio channel measurement campaigns in angiography and ultrasonic inspection rooms. The measurement results revealed that the shapes of the power delay profiles in the angiography and ultrasonic imaging rooms were significantly different from that reported in the IEEE802.15 TG3c and IEEE802.11 TGad channel models. For this reason, novel model structures were developed to model radio channels in these hospital scenarios accurately. Statistical descriptions of the channel model parameters are given based on the measurements, and, finally, implementation guidelines of the channel models are provided. The channel model validation results show a good agreement of root-mean-square delay spread between channel model outputs and channel measurements. The channel model is useful for the performance evaluation of the wireless systems in hospital environments.
Article
Multi-input-multi-output (MIMO) radio channel sounders commonly employ a time-division-multiplexing (TDM) technique to switch between transmit (TX) and receive (RX) antennas. The TDM-based switching enables very cost-effective solutions. Nevertheless, it can cause measurement errors due to phase noise in the local oscillators. In typical MIMO applications with a relatively small number of TX and RX antennas, the measurement cycle for a single snapshot of a MIMO radio channel is so short that independent or white Gaussian noise samples cannot be assumed. Indeed, the characteristics of the phase noise depend on the observing-time scale and the local oscillator design in the TX and the RX. In free-running systems, in which the local oscillators of the TX and the RX employ their own clocks, the properties of the phase noise have a strong dependence on the scale of the observing time. In particular, the short-term characteristics of the phase noise have not been considered in literature regarding MIMO measurements. In this paper, the characteristics of the short-term phase noise in time-switched MIMO radio channel measurements are disclosed. We show also that the Allan deviation, which commonly characterizes the frequency stability of the local oscillators, does not apply well to the short-term scale. Instead, an autoregressive model that is well suited for modeling of correlated noise is applied to characterize the short-term behavior of the phase noise. Finally, the effect of short-term phase noise on the estimation of MIMO channel capacity is analyzed. We also derive an upper bound for the ergodic channel capacity and show that it is dependent on the distribution of the largest eigenvalue of the noise covariance matrix. The results reveal that the effect of short-term phase noise always overestimates MIMO channel capacity.
Conference Paper
A widespread design for multiple-input multiple-output (MIMO) radio channel measurement devices (sounders) is based on time-division multiplexed switching of a single transmit/receive radio frequency (RF) chain into the elements of a transmit/receive antenna array. While being cost-effective, such a solution can cause significant measurement errors due to phase noise in the local oscillators. We analyze the impact of phase noise on MIMO channel measurement accuracy and show that it can lead to overestimation of channel capacity of up to 100% in practice. Furthermore, we demonstrate that the impact of phase noise is most pronounced if the physical channel has low rank (typical for line-of-sight or low scattering scenarios). The extreme case of a rank-1 physical channel is analyzed in detail.
Conference Paper
This paper presents a new wideband indoor channel sounder dedicated to the 60 GHz band. Based on the sliding correlation technique, it is optimized to perform long term measurement campaign without undersampling the fast varying impulse response. Some measurement results with Doppler analysis are presented
Article
This paper describes a developed wideband millimeter-wave radio channel sounder, which is based on the previously developed 2- and 5-GHz channel-sounder concept. Performance is analyzed, and examples of measurements, analysis, and comparison to lower frequencies are given. The sounder enables wideband (3-dB bandwidth of 100 MHz) measurements with continuous phase and excellent link budged without a cable connection between the transmitter and the receiver.
Article
Coherent wideband frequency-domain measurements of the complex frequency response of millimeter wave indoor radio channels are discussed. In addition, results of measurements performed in a 2 GHz band centered around 58 GHz will be presented. It is shown that a 40 dB dynamic range and a 400 ns aliasing-free range are sufficient for a correct estimation of the rms delay spread from the measurement data
Radio wave propagation and antennas for millimeter wave communications
• M Kyrö
Wide-band channel sounding in the bands above 2GHz
• S M Feeney