GHz Wireless Personal Area Networks Research Articles

Assessment of LTCC-Based Dielectric Flat Lens Antennas and Switched-Beam Arrays for Future 5G Millimeter-Wave Communication Systems

This paper presents the design, low-temperature co-fired ceramics (LTCC) fabrication, and full experimental verification of novel dielectric flat lens antennas for future high data rate 5G wireless communication systems in the 60 GHz band. We introduce and practically completely evaluate and compare the performance of three different inhomogeneous gradient-index dielectric lenses with the effective parameters circularly and cylindrically distributed. These lenses, despite their planar profile antenna configuration, allow full 2-D beam scanning of high-gain radiation beams. A time-domain spectroscopy system is used to practically evaluate the permittivity profile achieved with the LTCC manufacturing process, obtaining very good results to confirm the viability of fabricating inhomogeneous flat lenses in a mass production technology. Then, the lenses performance is evaluated in terms of radiation pattern parameters, maximum gain, beam scanning, bandwidth performance, efficiencies, and impedance matching in the whole frequency band of interest. Finally, the performance of the three lenses is also experimentally evaluated and compared to a single omni-directional antenna and to a ten-element uniform linear array of omni-directional antennas in real 60 GHz wireless personal area network indoor line-of-sight (LOS) and obstructed-LOS environments, obtaining interesting and promising remarkable results in terms of measured received power and root-mean-square delay spread. At the end of this paper, an innovative switched-beam antenna array concept based on the presented cylindrically distributed effective parameters lens is also introduced and completely evaluated, confirming the potential applicability of the proposed antenna solution for future 5G wireless millimeter-wave communication system.

High-Gain Wideband Partially Reflecting Surface Antenna for 60 GHz Systems

In this letter, a high-gain wideband antenna for 60 GHz wireless personal area networks is proposed. It consists of an inset-fed microstrip antenna with a partially reflecting surface (PRS) acting as a Fabry-Perot cavity. Good agreement was achieved between simulated and measured data, showing a wide bandwidth, covering two channels of the 60 GHz band and a maximum experimental gain of 16.4 dBi in the broadside direction at 60 GHz. The proposed structure meets the IEEE 802.15.3c standard requirements in terms of gain and bandwidth while the novel shape of the PRS array makes it smaller compared to existing 60 GHz Fabry-Perot antennas. Moreover, a low-cost printed circuit board technology is used to manufacture antenna prototype.

Throughput maximization for cooperative 60 GHz wireless personal area networks

Transmission in the 60 GHz frequency band performs poorly in long-distance direct links due to the large path loss. The received signal strength can be relatively weak if the line-of-sight path is blocked by obstacles. A device cooperation approach, which effectively combats the severe path loss thereby improving the overall throughput for wireless personal area networks (WPANs), is proposed in this paper. Throughput maximization is formulated as a linear programming problem and the optimal solutions are provided in each case. Comprehensive simulations are performed to quantify the performance of the cooperative approach with different antenna models and spatial reuse strategies. The effect of minor-lobe, imperfect information and other factors are investigated under different network settings. The performance analysis presented here can provide guidelines for the design of cooperative 60 GHz WPANs.

Toward Robust Relay Placement in 60 GHz mmWave Wireless Personal Area Networks with Directional Antenna

Multimedia streaming applications with stringent QoS requirements in 60 GHz mmWave wireless personal area networks (WPANs) demand high rate and low latency data transfer as well as little service disruption. In this paper, we consider the problem of robust relay placement in 60 GHz WPANs with directional antenna. Relays forward traffic from transmitter devices to receiver devices facilitating i) the primary communication path for non-line-of-sight (NLOS) transceiver pairs, and ii) secondary (backup) communication path for line-of-sight (LOS) or NLOS transceiver pairs. By incorporating a classic directional antenna model and characterizing the link contention, we formulate the robust minimum relay placement problem and the robust maximum utility relay placement problem with the objective to minimize the number of relays deployed and maximize the network utility, respectively. Efficient algorithms are developed to solve both problems and have been shown to incur less service disruption in presence of moving subjects that may block the LOS paths in the environment.

A SUC-Based Full-Binary 6-bit 3.1-GS/s 17.7-mW Current-Steering DAC in 0.038 mm$^{2}$

A 6-bit full-binary compact and low-power current-steering digital-to-analog converter (DAC) designed for 60-GHz Wireless Personal Area Network applications is presented. The closely located circuit components based on the stacked unit cell minimize the parasitic capacitance and enhance the high-frequency dynamic linearity. The proposed binary structure realizes a compact DAC by eliminating the need for additional circuits, such as thermometer decoders, and thus reduces power consumption. A prototype 6-bit 3.1-GS/s full-binary DAC was fabricated in a 90-nm CMOS process. The DAC exhibits a spurious-free dynamic range of >37.2 dB up to 3.1 GS/s over the Nyquist input. The chip consumes 17.7 mW of power and occupies 0.038 mm $^{2}$ of core size.

9.99 mW 4.8 dB NF 57-81 GHz CMOS low-noise amplifier for 60 GHz WPAN system and 77 GHz automobile radar system

A low-power and wideband two-stage millimeter-wave low-noise amplifier (LNA) for 60 GHz wireless personal area network system and 77 GHz automotive radar system using standard 90 nm CMOS technology is reported. T-match technique is used to achieve simultaneously wideband input and output impedance matching, wideband power gain (S21), and wideband noise figure (NF). The LNA consumes 9.99 mW, achieving S11 better than −−10 dB for frequencies of 57.6–81.8 GHz, and S12 better than −−29.1 dB for frequencies of 10–110 GHz. Additionally, high and flat S21 of 11.2 ± 1.5 dB is achieved for frequencies of 57.9–80.4 GHz, which means the corresponding 3-dB bandwidth is 22.5 GHz. Furthermore, the LNA achieves minimum NF of 4.8 dB at 76 GHz and NF of 6.2 ± 1.4 dB for frequencies of 76–84 GHz, one of the best NF results ever reported for a CMOS or SiGe BiCMOS LNA with operation frequency around 77 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:594–600, 2015

Concurrent Channel Time Allocation for Resource Management in WPANs

This paper presents a concurrent channel time allocation scheme used in the reservation period for concurrent transmissions in 60-GHz wireless personal area networks (WPANs). To this end, the proposed resource allocation scheme includes an efficient method for creating a concurrent transmission group by using a table that indicates whether individual streams experience interference from other streams or not. The coordinator device calculates the number of streams that can be concurrently transmitted with each stream and groups them together on the basis of the calculation result. Then, the coordinator device allocates resources to each group such that the streams belonging to the same group can transmit data concurrently. Therefore, when the piconet coordinator (PNC) allocates the channel time to the individual groups, it should allow for maximizing the overall capacity. The performance evaluation result demonstrates that the proposed scheme outperforms the random grouping scheme in terms of the overall capacity when the beamwidth is 30° and the radiation efficiency is 0.9.

Throughput Maximization for 60 GHz WPANs via Device Cooperation

With directional transmission, 60 GHz wireless personal area networks (WPAN) are capable of providing larger spatial reuse ratio as compared to omni-directional networks. In this work, a device cooperation scheme is proposed to improve throughput of the 60 GHz WPAN that employs spatial reuse. The throughput maximization is formulated as a linear programming problem and an optimal solution is provided. WPAN performance with and without device cooperation is studied via simulations. The results demonstrate that device cooperation provides significant throughput improvement as compared to non-cooperative transmission.

멀티-기가비트 WPAN 시스템을 위한 고속 QC-LDPC 복호기 구조

60GHz 멀티-기가비트 WPAN 시스템을 위한 고속 QC-LDPC 복호기의 구조를 제안한다. 제안한 QC-LDPC 복호기 설계를 위하여 4 블록-병렬 계층 복호 기술과 fixed wire network 기술이 적용 되었다. 2단 파이프라이닝과 4 블록-병렬 계층 복호기술은 동작 주파수와 데이터 처리량을 개선시키는데에 큰 효과가 있다. 또한 본 제안한 복호기 구조에서 스위치 네트워크를 구현하여 위하여 fixed wire network로 간단하게 구현될 수 있으면 하드웨어 복잡도를 크게 감소시킬 수 있다. 제안한 672-비트, rate-1/2인 QC-LDPC 복호기 구조는 90-nm CMOS 표준 셀을 이용해 설계 및 합성하였다. 성능 분석 결과 제안한 QC-LDPC 복호기 구조는 794K 게이트를 가지며 클락 속도 290MHz 에서 작동한다. 12-iteration일 때 데이터 처리율은 3.9Gbps 이며 60GHz WPAN 시스템에 적용되어 사용 될 수 있다.

On the Efficient Beam-Forming Training for 60GHz Wireless Personal Area Networks

In this article, we suggest an efficient beam switching technique for the emerging 60GHz wireless personal area networks. Given the pre-specified beam codebooks, the beam switching process, aiming to identify the best beam-pair for data transmissions, is formulated as a global optimization problem in a two-dimension plane that is formed by the potential beam pattern index. As the analytical gradient information of the objective reward function is practically unavailable, Rosenbrock numerical algorithm is properly adopted to implement beam searching, by implicitly approaching and exploiting the gradient descent direction through the numerical pattern-search mechanic. In order to enhance search performance, furthermore, a novel initialization process is presented to provide the feasible initial solution for Rosenbrock search. Inspired by the appealing conception of small-region dividing and conquering, this pre-search algorithm can efficiently reduce the search scope and hence improve the success probability. The developed beam switching technique, i.e. an initialization process followed by Rosenbrock search, exhibits a much lower complexity than the current state-of-the-art strategies. It is demonstrated from both theoretical analysis and numerical experiments that, compared with the existing popular methods, the required protocol overhead of the new beam-training procedure can be significantly reduced, accompanying the power consumption of 60GHz devices.

Integrated 60-GHz Antenna on Multilayer Organic Package With Broadside and End-Fire Radiation

Existing antenna and array systems for 60-GHz wireless personal area network communications suffer from inherent poor radiation at grazing angles. This limitation is overcome in this work with a highly integrated antenna module that combines both broadside and end-fire radiators in a single multilayer organic package. Liquid crystal polymer and Rogers RO3003 are used to implement a small form factor (12.5 mm × 10 mm × 1.3 mm) antenna architecture. The co-designed broadside and end-fire antennas are characterized and measured for operation in the 57-66-GHz frequency range. Measured boresight gains of 8.7 and 10.9 dBi are achieved for the broadside and end-fire antennas while maintaining 35-45-dB isolation between both antennas. The numerically estimated radiation efficiency is found to be 92.5% and 78.5% for the broadside and end-fire elements. These antennas are orthogonally polarized and suitable for frequency reuse. Integrated circuits are mounted inside recessed cavities to realize a fully active antenna module with beam switching or simultaneous radiation. To the best of our knowledge, this is the first publication of a single package multilayer integration of millimeter-wave active antennas with both azimuth and elevation coverage.

Axial Ratio Bandwidth Enhancement of 60-GHz Substrate Integrated Waveguide-Fed Circularly Polarized LTCC Antenna Array

A substrate integrated waveguide (SIW)-fed circularly polarized (CP) antenna array with a broad bandwidth of axial ratio (AR) is presented for 60-GHz wireless personal area networks (WPAN) applications. The widened AR bandwidth of an antenna element is achieved by positioning a slot-coupled rotated strip above a slot cut onto the broadwall of an SIW. A 4 × 4 antenna array is designed and fabricated using low temperature cofired ceramic (LTCC) technology. A metal-topped via fence is introduced around the strip to reduce the mutual coupling between the elements of the array. The measured results show that the AR bandwidth is more than 7 GHz. A stable boresight gain is greater than 12.5 dBic across the desired bandwidth of 57-64 GHz.

Design of 40–108-GHz Low-Power and High-Speed CMOS Up-/Down-Conversion Ring Mixers for Multistandard MMW Radio Applications

In this paper, a pair of broadband, low-LO-power, low-dc-power, and high-speed up/down-conversion ring mixers are presented for multistandard millimeter-wave (MMW) radio applications. By employing a weak inversion biasing technique, the ring mixer can operate at a low LO drive level and low dc power while maintaining reasonable conversion gain performance. In addition, an IF transimpedance amplifier (TIA) buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW wireless Gigabit transmission. Using a 90-nm CMOS low-power process, the up-/down-conversion ring mixers are designed and fabricated based on the presented topology. The down-conversion ring mixer and up-conversion ring mixer exhibit flat measured conversion gain of -1 ± 2 dB and 0 ± 2 dB and dB from 40 to 110 GHz and 40 to 108 GHz, respectively. After biasing the transistors of the ring mixer core at weak inversion region, the presented down-conversion and up-conversion ring mixers can operate at low LO drive power, -2 and 0 dBm, respectively, even up to 100 GHz. For MMW wireless gigabit communication, gigabit binary phase-shift keying modulation signal test is successfully performed through a direct-conversion system in this work. The presented ring mixers are suitable for 60-GHz wireless personal area network, -E-band (71-76 GHz, 81-86 GHz, and 92-95 GHz) wireless fiber, and 77-GHz anti-collision radar applications.

A Small Package With 46-dB Isolation Between Tx and Rx Antennas Suitable for 60-GHz WPAN Module

A small package suitable for the mobile terminals of the 60-GHz wireless personal area network is proposed. Two antennas for Tx and Rx are integrated in the package. The antenna provides the end-fire radiation from the side face of the substrate. The package is mounted on the edge of a printed circuit board by using the ball grid array assembly. The antenna is composed of a post-wall waveguide and a slab waveguide with metal sidewalls. The gain and beamwidth are determined by the size of the slab waveguide. The sidewalls are for the design of the beamwidth in the -plane and for realizing the high isolation between Tx and Rx antennas. The beamwidths of the fabricated antenna were measured to be 47° and 46° in the - and -plane at 60 GHz, respectively. The gain more than 7.8 dBi was measured in the frequency range from 59 to 66 GHz. The package was fabricated for the evaluation of the isolation. The measured average isolation level between Tx and Rx antenna was 46.0 dB in the frequency range above. The antenna characteristics and isolation level are sufficient for the 60-GHz WPAN system.

Enabling Multi-Hop Concurrent Transmissions in 60 GHz Wireless Personal Area Networks

Millimeter-wave (mmWave) communications is a promising enabling technology for high rate (Giga-bit) multimedia applications. However, because of the high propagation loss at 60 GHz band, mmWave signal power degrades significantly over distance. Therefore, a traffic flow being transmitted over multiple short hops can attain higher throughput than that over a single long hop. In this paper, we first design a hop selection metric for the piconet controller (PNC) to select appropriate relay hops for a traffic flow, aiming to improve the flow throughput and balance the traffic loads across the network. We then propose a multi-hop concurrent transmission (MHCT) scheme to exploit the spatial capacity of mmWave WPANs by allowing nodes to transmit concurrently in communication links without causing harmful interference. The analysis of concurrent transmission probability and time division multiplexing demonstrates that the MHCT scheme is capable of improving the time slot utilization. Extensive simulations are conducted to validate the analytical results and demonstrate that the proposed MHCT scheme can improve the average traffic flow throughput and network throughput.

A Low Power Frequency Synthesizer for 60-GHz Wireless Personal Area Networks

In this brief, a 60-GHz frequency synthesizer for wireless personal area networks is designed using 0.13- μm CMOS technology. The synthesizer operates at 60 GHz with phase noises of -98, -117, and -128 dBc/Hz at 1-, 10-, and 40-MHz frequency offsets, respectively. The 60-GHz clock is generated by combining a phase-locked loop (PLL) and an injection-locked oscillator. The PLL provides frequency tuning of the 60-GHz voltage-controlled oscillator (VCO) using replica tuning. A pulse train is generated using a novel passive delay-locked loop and a CMOS pulse generator. This pulse train is then used for filtering the phase noise of 60-GHz VCO up to a high offset frequency. The total power consumption of the frequency synthesizer is 57 mW with a 1.2-V power supply.

Design of 1.2-V Broadband High Data-Rate MMW CMOS I/Q Modulator and Demodulator Using Modified Gilbert-Cell Mixer

In this paper, low-voltage evolution and high-speed operation mixer design are presented for millimeter-wave (MMW) CMOS in-phase/quadrature (I/Q) modulator and demodulator. The modified Gilbert-cell mixer architecture, which eliminates the three-level transistors stacking in the conventional Gilbert-cell mixer, can operate at a reduced supply voltage while maintaining reasonable performance. In addition, IF transimpedance amplifier buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW gigabit wireless transmission link applications. Using a 0.13-μm CMOS process, the I/Q modulator and demodulator formed with the modified Gilbert-cell mixers are demonstrated at the MMW. Under 1.2-V standard supply voltage, the modulator and demodulator exhibit excellent conversion gain (CG) flatness of -3.5 ±1.5 dB and -3 ±1.5 dB from 41 to 69.5 GHz and 31 to 69 GHz, respectively. For 60-GHz wireless personal area network applications, π/4 differential quadrature phase-shift keying, 16 quadrature amplitude modulation, and binary phase-shift keying modulation signal tests are successfully performed through the direct-conversion system. The results show that the presented monolithic microwave integrated circuits can operate at low-voltage and low-power while providing good CG and high data rate, even up to multigigabit.

Decision-directed phase noise compensation for millimeter-wave single carrier systems with iterative frequency-domain equalization

This paper proposes a receiver that repeats iterative frequency-domain equalization (FDE) and decision-directed phase noise compensation (DD-PNC) to alleviate degradation due to the phase noise for millimeter-wave single carrier (SC) systems. High bit-rate SC-FDE transceivers based on the single-chip Si RF-CMOS IC technology in the 60-GHz millimeter-wave band have been extensively studied for wireless personal area network (WPAN) systems, and the relatively large phase noise in a phase-locked loop (PLL) synthesizer severely degrades transmission performance. In an initial processing of the proposed receiver, a cyclic prefix (CP)-based phase noise compensator (CP-PNC) removes the phase noise from a time-domain received signal by using CP, which is known to the receiver, and the channel is equalized by the iterative FDE using the conventional minimum mean-square-error (MMSE) weight. In an iterative processing, DD-PNC estimates the phase noise each symbol by exploiting an output of a channel decoder, and then compensates the time-domain received signal for the phase noise by using the estimate. In order to equalize the compensated received signal, the iterative FDE performs both the MMSE filtering and residual inter-symbol interference cancelation using the decoder output. Computer simulations following the 60-GHz WPAN standard demonstrate that in the 64QAM with the coding rate of 3/4, the proposed receiver with three iterations can drastically remove the phase noise of −85 dBc/Hz at 1 MHz offset, and that it can achieve excellent transmission performance.

Beam codebook based beamforming protocol for multi-Gbps millimeter-wave WPAN systems

In order to realize high speed, long range, reliable transmission in millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs), we propose a beamforming (BF) protocol realized in media access control (MAC) layer on top of multiple physical layer (PHY) designs. The proposed BF protocol targets to minimize the BF set-up time and to mitigate the high path loss of 60 GHz WPAN systems. It consists of 3 stages, namely the device (DEV) to DEV linking, sector-level searching and beam-level searching. The division of the stages facilitates significant reduction in setup time as compared to BF protocols with exhaustive searching mechanisms. The proposed BF protocol employs discrete phase-shifters, which significantly simplifies the structure of DEVs as compared to the conventional BF with phase-and-amplitude adjustment, at the expense of a gain degradation of less than 1 dB. The proposed BF protocol is a complete design and PHY-independent, it is applicable to different antenna configurations. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. Furthermore, based on the codebooks with four phases per element, around 15.1 dB gain is achieved by using eight antenna elements at both transmitter and receiver, thereby enabling 1.6 Gbps-data-streaming over a range of three meters. Due to the flexibility in supporting multiple PHY layer designs, the proposed protocol has been adopted by the IEEE 802.15.3c as an optional functionality to realize Gbps communication systems.

Blockage and directivity in 60 GHz wireless personal area networks: from cross-layer model to multihop MAC design

We present a cross-layer modeling and design approach for multigigabit indoor wireless personal area networks (WPANs) utilizing the unlicensed millimeter (mm) wave spectrum in the 60 GHz band. Our approach accounts for the following two characteristics that sharply distinguish mm wave networking from that at lower carrier frequencies. First, mm wave links are inherently directional: directivity is required to overcome the higher path loss at smaller wavelengths, and it is feasible with compact, low-cost circuit board antenna arrays. Second, indoor mm wave links are highly susceptible to blockage because of the limited ability to diffract around obstacles such as the human body and furniture. We develop a diffraction-based model to determine network link connectivity as a function of the locations of stationary and moving obstacles. For a centralized WPAN controlled by an access point, it is shown that multihop communication, with the introduction of a small number of relay nodes, is effective in maintaining network connectivity in scenarios where single-hop communication would suffer unacceptable outages. The proposed multihop MAC protocol accounts for the fact that every link in the WPAN is highly directional, and is shown, using packet level simulations, to maintain high network utilization with low overhead.