3,522 research outputs found
Guest editorial for the special issue on software-defined radio transceivers and circuits for 5G wireless communications
Yichuang Sun, Baoyong Chi, and Heng Zhang, Guest Editorial for the Special Issue on Software-Defined Radio Transceivers and Circuits for 5G Wireless Communications, published in IEEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 63 (1): 1-3, January 2016, doi: https://doi.org/10.1109/TCSII.2015.2506979.Peer reviewedFinal Accepted Versio
Millimeter Wave Communications with Reconfigurable Antennas
The highly sparse nature of propagation channels and the restricted use of
radio frequency (RF) chains at transceivers limit the performance of millimeter
wave (mmWave) multiple-input multiple-output (MIMO) systems. Introducing
reconfigurable antennas to mmWave can offer an additional degree of freedom on
designing mmWave MIMO systems. This paper provides a theoretical framework for
studying the mmWave MIMO with reconfigurable antennas. We present an
architecture of reconfigurable mmWave MIMO with beamspace hybrid analog-digital
beamformers and reconfigurable antennas at both the transmitter and the
receiver. We show that employing reconfigurable antennas can provide throughput
gain for the mmWave MIMO. We derive the expression for the average throughput
gain of using reconfigurable antennas, and further simplify the expression by
considering the case of large number of reconfiguration states. In addition, we
propose a low-complexity algorithm for the reconfiguration state and beam
selection, which achieves nearly the same throughput performance as the optimal
selection of reconfiguration state and beams by exhaustive search.Comment: presented at IEEE ICC 201
Baseband analog front-end and digital back-end for reconfigurable multi-standard terminals
Multimedia applications are driving wireless network operators to add high-speed data services such as Edge (E-GPRS), WCDMA (UMTS) and WLAN (IEEE 802.11a,b,g) to the existing GSM network. This creates the need for multi-mode cellular handsets that support a wide range of communication standards, each with a different RF frequency, signal bandwidth, modulation scheme etc. This in turn generates several design challenges for the analog and digital building blocks of the physical layer. In addition to the above-mentioned protocols, mobile devices often include Bluetooth, GPS, FM-radio and TV services that can work concurrently with data and voice communication. Multi-mode, multi-band, and multi-standard mobile terminals must satisfy all these different requirements. Sharing and/or switching transceiver building blocks in these handsets is mandatory in order to extend battery life and/or reduce cost. Only adaptive circuits that are able to reconfigure themselves within the handover time can meet the design requirements of a single receiver or transmitter covering all the different standards while ensuring seamless inter-interoperability. This paper presents analog and digital base-band circuits that are able to support GSM (with Edge), WCDMA (UMTS), WLAN and Bluetooth using reconfigurable building blocks. The blocks can trade off power consumption for performance on the fly, depending on the standard to be supported and the required QoS (Quality of Service) leve
Reconfigurable Antennas in mmWave MIMO Systems
The key obstacle to achieving the full potential of the millimeter wave
(mmWave) band has been the poor propagation characteristics of wireless signals
in this band. One approach to overcome this issue is to use antennas that can
support higher gains while providing beam adaptability and diversity, i.e.,
reconfigurable antennas. In this article, we present a new architecture for
mmWave multiple-input multiple-output (MIMO) communications that uses a new
class of reconfigurable antennas. More specifically, the proposed lens-based
antennas can support multiple radiation patterns while using a single radio
frequency chain. Moreover, by using a beam selection network, each antenna beam
can be steered in the desired direction. Further, using the proposed
reconfigurable antenna in a MIMO architecture, we propose a new signal
processing algorithm that uses the additional degrees of freedom provided by
the antennas to overcome propagation issues at mmWave frequencies. Our
simulation results show that the proposed reconfigurable antenna MIMO
architecture significantly enhances the performance of mmWave communication
systems
MAC-Oriented Programmable Terahertz PHY via Graphene-based Yagi-Uda Antennas
Graphene is enabling a plethora of applications in a wide range of fields due
to its unique electrical, mechanical, and optical properties. In the realm of
wireless communications, graphene shows great promise for the implementation of
miniaturized and tunable antennas in the terahertz band. These unique
advantages open the door to new reconfigurable antenna structures which, in
turn, enable novel communication protocols at different levels of the stack.
This paper explores both aspects by, first, presenting a terahertz
Yagi-Uda-like antenna concept that achieves reconfiguration both in frequency
and beam direction simultaneously. Then, a programmable antenna controller
design is proposed to expose the reconfigurability to the PHY and MAC layers,
and several examples of its applicability are given. The performance and cost
of the proposed scheme is evaluated through full-wave simulations and
comparative analysis, demonstrating reconfigurability at nanosecond granularity
with overheads below 0.02 mm and 0.2 mW.Comment: Accepted for presentation in IEEE WCNC '1
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Per-Core DVFS with Switched-Capacitor Converters for Energy Efficiency in Manycore Processors
Integrating multiple power converters on-chip improves energy efficiency of manycore architectures. Switched-capacitor (SC) dc-dc converters are compatible with conventional CMOS processes, but traditional implementations suffer from limited conversion efficiency. We propose a dynamic voltage and frequency scaling scheme with SC converters that achieves high converter efficiency by allowing the output voltage to ripple and having the processor core frequency track the ripple. Minimum core energy is achieved by hopping between different converter modes and tuning body-bias voltages. A multicore processor model based on a 28-nm technology shows conversion efficiencies of 90% along with over 25% improvement in the overall chip energy efficiency
Hardware prototyping and validation of a W-ΔDOR digital signal processor
Microwave tracking, usually performed by on ground processing of the signals coming from a spacecraft, represents a crucial aspect in every deep-space mission. Various noise sources, including receiver noise, affect these signals, limiting the accuracy of the radiometric measurements obtained from the radio link. There are several methods used for spacecraft tracking, including the Delta-Differential One-Way Ranging (ΔDOR) technique. In the past years, European Space Agency (ESA) missions relied on a narrowband ΔDOR system for navigation in the cruise phase. To limit the adverse effect of nonlinearities in the receiving chain, an innovative wideband approach to ΔDOR measurements has recently been proposed. This work presents the hardware implementation of a new version of the ESA X/Ka Deep Space Transponder based on the new tracking technique named Wideband ΔDOR (W-ΔDOR). The architecture of the new transponder guarantees backward compatibility with narrowband ΔDOR
Hardware implementation of a versatile low-cost mixed-signal platform for SDR experimentation
This paper presents the design of a reconfigurable mixedsignal
platform used in the Software Defined Radio context.It is a single board part of a pre-existing modular system operating from 1.6 to 2.5 GHz that supports GSM1800,DCS1800, PCS1900, UMTS-FDD, UMTS-TDD and 802.11b standards. Its purpose is to facilitate configuration and data exchange between a computer and an RF transceiver. Technical choices, design and overall
performances of the prototype are discussed
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