Inter-BSs virtual private network for privacy and security enhanced 60 GHz radio-over-fiber system

A novel inter-basestations (inter-BSs) based virtual private network (VPN) for the privacy and security enhanced 60 GHz radio-over-fiber (RoF) system using optical code-division multiplexing (OCDM) is proposed and demonstrated experimentally. By establishing inter-BSs VPN overlaying the network structure of a 60 GHz RoF system, the express and private paths for the communication of end-users under different BSs can be offered. In order to effectively establish the inter-BSs VPN, the OCDM encoding/decoding technology is employed in the RoF system. In each BS, a 58 GHz millimeter-wave (MMW) is used as the inter-BSs VPN channel, while a 60 GHz MMW is used as the common central station (CS)–BSs communication channel. The optical carriers used for the downlink, uplink and VPN link transmissions are all simultaneously generated in a lightwave-centralized CS, by utilizing four-wave mixing (FWM) effect in a semiconductor optical amplifier (SOA). The obtained results properly verify the feasibility of our proposed configuration of the inter-BSs VPN in the 60 GHz RoF system.     

Low power high data rate wireless endoscopy transceiver

A low power high data rate wireless endoscopy transceiver is presented. Transceiver architecture, circuit topologies and design trade-offs have been considered carefully to satisfy the tight requirements of the medical endoscopy capsule: lower power consumption, high integration degree and high data rate. The prototype, implemented in 0.25 μm CMOS, integrates a super-heterodyne receiver and a super-heterodyne transmitter on a single chip together with an integrated RF local oscillator and LO buffers. The digital modulation and demodulation is also implemented in analog field and no data converters are needed for the whole endoscopy capsule. The measured sensitivity of the receiver is about −70 dBm with a data rate 256 kbps, and the measured output power of the transmitter could achieve −23 dBm with a data rate 1 Mbps. The transceiver operates from a power supply of 2.5 V, while only consuming 15 mW in receiver (RX) mode and 14 mW in transmitter (TX) mode.     

Software-driven sensor networks for short-range shallow water applications

Most existing underwater networks target deep and long range oceanic environments, which has led to the design of power hungry and expensive underwater communication hardware. Because of prohibitive monetary and energy cost of currently over-engineered communication hardware, dense deployments of shallow water sensor networks remain an elusive goal. To enable dense shallow water networks, we propose a network architecture that builds on the success of terrestrial sensor motes and that relies on the coupling of software modems and widely available speakers and microphones in sensor motes to establish acoustic communication links. In this paper, we analytically and empirically explore the potential of this acoustic communication system for the underwater environment. Our experimental approach first profiles the hardware in water after waterproofing the components with elastic membranes. The medium profiling results expose the favorable frequencies of operation for the hardware, enabling us to design a software FSK modem. Subsequently, our experiments evaluate the data transfer capability of the underwater channel with 8-frequency FSK software modems. The experiments within a 17 × 8 m controlled underwater environment yield an error-free channel capacity of 24 bps, and they also demonstrate that the system supports date rates between 6 and 48 bps with adaptive fidelity.     

Joint downlink and uplink resource allocation for multi-carrier SWIPT system

A multi-carrier simultaneous wireless information and power transfer (SWIPT) communication system including one base station (BS) and one user was investigated,where both uplink and downlink adopt orthogonal frequency division multiplexing (OFDM).In the downlink,the BS transmited information and power to the user simultaneously.In the uplink,the user transmited information to the BS by using the power harvested from the BS in the downlink.The weighted sum of the downlink and uplink achievable rates by jointly optimizing subcarrier allocation and power allocation of the uplink and downlink were aimed to maximized.An optimal algorithm to solve the joint resource allocation problem was proposed,which was based on the Lagrange duality method and the ellipsoid method.Finally,the result shows the performances of the proposed algorithm by computer simulations.     

Bidirectional and simultaneous transmission of baseband and wireless signals over RSOA based WDM radio-over-fiber passive optical network using incoherent light injection technique

Reflective semiconductor optical amplifier (RSOA) based wavelength division multiplexed radio-over-fiber passive optical network (WDM−RoF−PON) has been proposed and demonstrated, to transmit 2.5 Gbps baseband (BB) and 1.25 Gbps wireless data in downstream and 1 Gbps BB data signal in upstream over 25-km single-mode fiber (SMF), and wireless downstream signal over 25-km SMF as well as 5.2 m free space in air. In the downstream, 2.5 Gbps BB data and 1.25 Gbps wireless data are modulated using single-electrode Mach–Zehnder modulator (SD-MZM) based on double-sideband with optical carrier suppression (DSBCS) scheme and simultaneously transmitted by incoherent light injection technique and employing fiber Bragg grating (FBG) at the base station. RSOA is utilized at the user end to reuse the carrier for uplink transmission. High receiver sensitivity, low bit-error-rate (BER) and excellent eye-diagram, eye height are achieved in our proposed network system and the results affirm the acceptability of proposed RSOA based WDM−RoF−PON.     

Utilization of self-injection Fabry–Perot laser diode for long-reach WDM-PON

In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry–Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation.     

A low-voltage low-power CMOS transmitter front-end using current mode approach for 2.4 GHz wireless communications

This paper presents a low-voltage low-power transmitter front-end using current mode approach for 2.4 GHz wireless communication applications, which is fabricated in a chartered 0.18 μm CMOS technology. The direct up-conversion is implemented with a current mode mixer employing a novel input driver stage, which can significantly improve the linearity and consume a small amount of DC current. The driver amplifier utilizes a transimpedance amplifier as the first stage and employs an inter-stage capacitive cross-coupling technique, which enhances the power conversion gain as well as high linearity. The measured results show that at 2.4 GHz, the transmitter front-end provides 15.5 dB of power conversion gain, output P?1 dB of 3 dBm, and the output-referred third-order intercept point (OIP3) of 13.8 dBm, while drawing only 6 mA from the transmitter front-end under a supply voltage of 1.2 V. The chip area including the testing pads is only 0.9 mm×1.1 mm.     

A compact low-profile dual-band antenna for WLAN and WAVE applications

A compact and low-profile patch antenna with a simple structure is presented for the wireless local-area network (WLAN) and the wireless access in the vehicular environment (WAVE) applications. The proposed antenna with an overall size of only 23 mm × 25 mm is fed by a coplanar waveguide (CPW), and yields 10-dB impedance bandwidths of about 250 MHz centered at 2.44 GHz and of about 22% ranging from 5.13 to 6.38 GHz suitable for the WLAN 2.4/5.2/5.8 GHz and the WAVE 5.9 GHz (IEEE 802.11p) applications. Also, good dipole-like patterns and high average antenna gain of ≥2.3 dBi over the operating bands have been obtained. In this design, resonance can be effectively controlled by simply tuning the shaped slots on the patch. Mechanism of mode excitations and effect of the added slot's length on resonance for the proposed antenna are examined and discussed in detail. The experimental results have validated the proposed design as useful for modern mobile communication.     

Heuristic receiver for implantable UWB applications

High data rate implantable wireless systems come with many challenges, chief among them being low power operation and high linearity. A low noise amplifier (LNA) designed for this application must include high gain, low noise figure (NF) and better linearity at low power consumption within the required frequency band. The down converter also requires a passive mixer to achieve low power and better linearity. In this paper, design is based on an Impulse Response (IR) Ultra-wideband (UWB) receiver operating at (3.1–5) GHz implemented in 0.25 μm CMOS Silicon on Sapphire (SOS). This paper reports the design and measurement of a UWB receiver with a designed and measured linearity of 17 dBm, a gain of 30.5 dB and a minimum NF of 4.5 dB, which make it suitable for implantable radio applications.     

Full-duplex fiber-wireless link with 40 Gbit/s 16-QAM signals for alternative wired and wireless accesses based on homodyne/heterodyne coherent detection

A novel full-duplex fiber-wireless link with 40 Gbit/s 16-ary quadrature amplitude modulation (QAM) signals is proposed to provide alternative wired and wireless accesses for the user terminals. In the central station (CS), the downstream signal for wired and wireless accesses is beared onto the CW laser source via an optical I/Q modulator to realize the QAM modulation. At the hybrid optical network unit (HONU), a tunable laser is used to provide coherent optical local oscillator for homo-/heterodyne beating to coherently down-convert the baseband optical signal to the baseband electrical one for wired access or to the mm-wave one for wireless access according to the requirement of the user terminals. Simultaneously, the lightwave from the tunable laser is also used as the uplink optical carrier for either wired or wireless access, and is modulated colorlessly by the baseband or mm-wave signal of the uplink alternatively. After filtering, only one tone carrying the uplink signal is transmitted back to the CS even for the wireless access. The theoretical analysis and simulation results show that our proposed full-duplex link for the alternative wired and wireless accesses maintains good performance even when the transmission link with standard single mode fiber (SSMF) is extended to 30 km.     

Power assignment problems in wireless communication: Covering points by disks,reaching few receivers quickly,and energy-efficient travelling salesman tours

In this paper, we present approximation algorithms for a variety of problems occurring in the design of energy-efficient wireless communication networks. We first study the k-station network problem, where for a set S of stations and some constant k, one wants to assign transmission powers to at most k senders such that every station in S can receive a signal from at least one sender. We give a (1 + ?)-approximation algorithm for this problem. The second problem deals with energy-efficient networks, allowing bounded hop multicast operations, that is given a subset C of the stations S and a designated source node s ∈ S, we want to assign powers to the sending stations, such that every node in C can be reached by a transmission from s within k hops. For this problem, we provide an algorithm which runs in time linear in ∣S∣. The last problem deals with a variant of the non-metric TSP problem where the edge costs correspond to the Euclidean distances to the power of some α ? 1; this problem is motivated by data aggregation schemes in wireless sensor networks. We provide a simple constant approximation algorithm, which improves upon previous results when 2 ? α ? 2.7.     

A tuned rectifier for RF energy harvesting from ambient radiations

A circuit topology based on accumulate-and-use philosophy has been developed to harvest RF energy from ambient radiations such as those from cellular towers. Main functional units of this system are antenna, tuned rectifier, supercapacitor, a gated boost converter and the necessary power management circuits. Various RF aspects of the design philosophy for maximizing the conversion efficiency at an input power level of 15 μW are presented here. The system is characterized in an anechoic chamber and it has been established that this topology can harvest RF power densities as low as 180 μW/m² and can adaptively operate the load depending on the incident radiation levels. The output of this system can be easily configured at a desired voltage in the range 2.2–4.5 V. A practical CMOS load – a low power wireless radio module has been demonstrated to operate intermittently by this approach. This topology can be easily modified for driving other practical loads, from harvested RF energy at different frequencies and power levels.     

SRR and S-shape slot loaded triple band notched UWB antenna

This paper demonstrates the design of a triple band notched ultrawideband circular microstrip patch antenna loaded with Complementary Split RingResonator (CSRR) and S-shaped slot in microstrip feed line. Complementary Split Ring Resonator slot and S-shaped slot are used to produce band notched characteristics for WiMAX band (3.30–3.60 GHz) and WLAN band (5.10–5.80 GHz) respectively. The downlink frequency band (7.25–7.75 GHz) of X-band for satellite communication is notched using Symmetrical Split Ring Resonator Pair (SSRRP) as electromagnetic coupling element near microstrip feed line which produces band stop characteristics. Measured results of fabricated antenna prototype are compared with simulated results and found in correspondence. The VSWR and vector current plots show evidence of the significant suppression in the desired frequency bands.     

115 Gbit/s downstream and 10 Gbit/s upstream TWDM-PON together with 11.25 Gbit/s wireless signal utilizing OFDM-QAM modulation

In this work, we propose and investigate a 115 Gbit/s (4 × 28.75 Gbit/s) downstream and 10 Gbit/s upstream time- and wavelength-division-multiplexing passive optical network (TWDM-PON) together with 11.25 Gbit/s wireless broadcasting signal using multi-band orthogonal-frequency-division-multiplexing (OFDM) modulation within 10 GHz bandwidth. Here, to compensate the power fading and chromatic dispersion in the higher frequency, we utilize a −0.7 chirp parameter Mach–Zehnder modulator (MZM) for the OFDM signal. Hence, negative power penalties of −0.3 and −0.4 dB in the downstream and broadcasting wireless signals; and power penalty of 0.3 dB in the upstream signal are measured at the bit error rate (BER) of 3.8 × 10⁻³ after 20 km standard single mode fiber transmission without dispersion compensation.     

A low-complexity UWB RF receiver based on a novel low noise amplifier

A novel low-complexity ultra-wideband UWB receiver is proposed for short-range wireless transmission communications without considering multipath effect. The receiver chip uses a low-complexity UWB non-coherent receiving system solution with the core module composed of squarer and low-pass filter. By introducing asymmetric gate series inductance and RCL parallel negative feedback loop into the two-stage push–pull amplifier, the low-noise amplification and input impedance matching at ultra-wide bandwidth were achieved. With only two inductors and self-biased function, the chip area and power consumption can be saved largely. The proposed UWB receiver chip was fabricated in a 0.18 μm RF CMOS technology. Experimental results show that it can achieve a bandwidth of 3–5 GHz, maximum receiving symbol rate of 250 Mbps, receiving sensitivity of −80 dBm and power consumption of 36 mW, providing a low-complexity and high-speed physical implementation of the short-range high-speed wireless interconnection between electronic devices in the future.     

Thermal-aware design and fault analysis of a DC/DC parallel resonant converter

In this paper a 3-D electrothermal (ET) analysis of a DC–DC parallel resonant converter (PRC) for constant current (CC) application is presented. A full 3-D ET simulation approach is proposed at application level to provide a support for the design stage and to analyse possible fault conditions inside the active devices. Simulations and measurements have been performed on a 100 W–2 A prototype of a PRC-CC circuit with 80 kHz nominal switching frequency.In particular, in the reported case study, the analysis has been focused on the full-bridge section of the circuit in order to prove the effect of the soft switching operation, introduced by the resonant technique, and consider the effect of possible fault conditions. To this purpose an unexpected short-circuit condition on a power MOSFET composing the H-bridge is considered, to evaluate the ET circuit behaviour and the time-to-failure of the power section. Considerations are carried out in terms of minimum requirements of protection circuits which must be fulfilled in order to avoid catastrophic system failure.A second power converter, rated for 1.5 kW, has been then designed, based on the same circuital topology, and an ET simulation has been performed in order to carry out considerations on the effect of mismatches among the input bridge devices.     

A low-distortion multi-bit sigma–delta ADC with mismatch-shaping DACs for WLAN applications

A low-distortion feed-forward MASH2_4b-2_4b sigma–delta analog-to-digital converter (ADC) for wireless local area network (WLAN) applications was presented. The converter exhibits improved performances than the ADCs which have been presented to date by adding a feedback factor in the second stage and employing a 2nd-order noise-shaping dynamic element matching (DEM) scheme. The feedback factor induces a zero in the noise transfer function (NTF) and therefore improves the in-band signal to noise and distortion ratio (SNDR) of the modulator. The mismatch-shaping DEM was introduced and applied to the 4-bit DACs in this paper to improve the resolution and linearity of the ADC. Fabricated in a 0.18 μm CMOS process with single 1.8 V supply voltage, the converter achieves a peak SNDR of 85.4 dB over a 10 MHz bandwidth which implies an effective number of bits (ENOB) of 13.90-bit. The spurious free dynamic range (SFDR) is –94 dB for a 1.25 MHz@–6dBFS input signal at 160 MHz sampling frequency. The occupied area is 0.44 mm² and dissipation power 23.4 mW.     

An inductorless wideband common-gate LNA with dual capacitor cross-coupled feedback and negative impedance techniques

A wideband common-gate (CG) low-noise amplifier (LNA) with dual capacitor cross-coupled (CCC) feedback and negative impedance techniques is presented for multimode multiband wireless communication applications. Double CCC technique boosts the input transconductance of the LNA, and low power consumption is obtained by using current-reuse technique. Negative impedance technique is employed to alleviate the correlation between the transconductance of the matching transistors and input impedance. Meanwhile, it also allows us to achieve a lower noise figure (NF). Moreover, current bleeding technique is adopted to allow the choice of a larger load resistor without sacrificing the voltage headroom. The proposed architecture achieves low noise, low power and high gain simultaneously without the use of bulky inductors. Simulation results of a 0.18-μm CMOS implementation show that the proposed LNA provides a maximum voltage gain of 25.02 dB and a minimum NF of 2.37 dB from 0.1 to 2.25 GHz. The input-referred third-order intercept point (IIP3) and input 1-dB compression point (IP_1dB) are better than –7.8 dBm and –19.2 dBm, respectively, across the operating bandwidth. The circuit dissipates 3.24 mW from 1.8 V DC supply with an active area of 0.03 mm².     

An NTF-enhanced incremental ΣΔ modulator using a SAR quantizer

In this paper, a noise transfer function (NTF) enhanced incremental sigma-delta (ΣΔ) modulator is presented. It employs a charge redistribution successive approximation register (SAR) analog-to-digital converter (ADC) in an error-feedback scheme to achieve an extra noise-shaping order. Using a multi-bit SAR quantizer not only improves the stability and power consumption but also facilitates the realization of both the adder situated in front of the quantizer and the whole error-feedback loop. As a design example, a multiplexed 2nd-order modulator based on the proposed architecture is simulated in TSMC 90 nm CMOS technology using Spectre with a 1 V single power supply. The simulation results show a signal-to-noise and distortion ratio (SNDR) of 85.3 dB within a signal bandwidth of 20 kHz (1 kHz/channel) at 5 MHz sampling frequency. The power consumption for each channel is 8.6 µW.     

Implementation and evaluation of 2D SEC-DED forward error correction scheme in wireless sensor networks

Numerous applications in wireless sensor networks (WSNs) require collecting data without loss during transmission, long-term sensing, and long system lifetime. Achieving reliable data transfer and long system lifetime is difficult because, from one hand, the wireless transfer is error prone, and, on the other, sensor node (SN), as battery powered device, is energy limited. By using some power-aware techniques, such as duty-cycling and power-gating, it is possible to reduce the energy consumption at an acceptable level. The requirements for higher level of reliability during wireless data transfer have increased the use of error correcting codes (ECCs). Codes represent an effective means of providing protection against injection of single-/double-/multiple bit errors over noisy communication channel. The two basic mechanisms to recover erroneous packets in any network are Automatic Repeat Request (ARQ), and Forward Error Correction (FEC). As energy consumption is a major issue in concern in WSN, packet retransmission is not an option and FEC would be preferred over ARQ. In this paper, an efficient scheme, based on two-dimensional (rectangular) block ECC code, referred as Two Dimensional Single Error Correction and Double Error Detection (2D SEC-DED), has been developed. By using 2D SEC-DED encoding all single-bit and 99.9% of double −/multiple-bit errors, within transferred packets, are recovered. In this way, the number of retransmissions, when WSN operates in harsh environmental (bit error rate (BER), BER > 10^− 4) is decreased, what means that not only energy saving but also extension of the transmit range (transmission distance between the transmitter and receiver), is achieved. As illustration, for indoor environment (the path loss exponent, also known as propagation constant or space loss factor, α = 4) at the target BER of 5 · 10^− 4, the proposed encoding scheme is able to improve the transmission distance by about 18 m or the received signal strength (RSSI) by about 8.5dBm compared to WSN without error correction (WSN which use Cycle Redundancy Check (CRC) encoding as error detection mechanism).