Craig Michie

On the Experimental Characterization of Beat Noise in 2-D Time-Spreading Wavelength-Hopping OCDMA Systems

The results of a preliminary experimental characterization of beat noise for the case of a particular two-dimensional time-spreading wavelength-hopping optical code family are presented. Beat noise is evaluated at a data rate of 2.5 Gb/s with and without time gating. Results indicate that this form of noise introduces significant system power penalties for both cases, with the former approach more robust in this respect

An Adjustable Gain-Clamped Semiconductor Optical Amplifier (AGC-SOA)

The operation of a semiconductor optical amplifier (SOA)-ring laser-based subsystem, with the capability to provide adjustable gain-clamped operation, will be described, and preliminary characterization results will be presented. The device uses two SOAs in a ring-cavity topology: one to amplify the signal and the other to control the gain. This type of subsystem finds applications in packet-based dynamic systems where it may be used for power equalization and linear amplification.

Polarization-Insensitive SOAs Using Strained Bulk Active Regions

The polarization dependent gain (PDG) and its control is a key issue for semiconductor optical amplifier devices. For the case of a strained bulk active region with lateral tapers, an analysis of the parameters that affect PDG is performed, and the magnitude of its variation is calculated. The critical design parameters are thus identified, and the expected PDG variance is discussed in the context of typical fabrication tolerances

Optically amplified passive optical networks: a power budget analysis

Passive optical networks (PONs) are being aggressively pursued as a means of delivering access network solutions. The cost benefits resulting from a reduction in the number of interfaces between nodes has enabled increasing deployment of a PON delivering fiber to the home and fiber to the curb. However, in many cases, the need for high split ratios or an extended-reach requires amplification to overcome additional losses. Erbium-doped amplifiers have a limited use in PONs since the operational wavelengths typically include backhaul at 1.3 mu m. Semiconductor optical amplifiers (SOAs) offer a cost-effective solution with a migration path toward integration; deployment options include its use as a preamplifier, booster, or midspan amplifier. We present a theoretical treatment that analyzes the amplified system operational requirements and justifies this analysis through the experiment. The analysis considers for the first time to our knowledge the dc offset that is introduced into the receiver as a result of the significant amplified spontaneous emission powers present in amplified PONs, where filter widths are typically 20 nm or greater.

A Broadcast/Multicast-Capable Carrier-Reuse WDM-PON

A novel broadcast/multicast-capable carrier-reuse WDM-PON architecture is proposed. Utilizing the splitting capability of a power splitter and the cyclic property of an arrayed waveguide grating (AWG) at the remote node, the broadcast channel and a dedicated downlink unicast channel can be overlaid and subsequently transmitted to each optical network unit (ONU) simultaneously. Since each ONU can receive a common broadcast channel with electronically coded information, the multicast function can be implemented in a higher layer, similar to the current multicast-capable E-PON or G-PON using IP multicast addresses through a single wavelength channel. Thus, there is no need for reconfiguration of physical connections for multicast services. The proposed approach is different from the approach of overlaying DPSK multicast data onto NRZ unicast data using the same wavelength. As such, this approach does not require an expensive DPSK receiver at each ONU, and high receiver sensitivity can be achieved since there is no need to restrict the extinction ratio (ER) of the NRZ unicast data to a small value. Simulation studies show that this WDM-PON provides acceptable performance with one 10 Gb/s broadcast channel and thirty-two 10 Gb/s downlink unicast channels, and thirty-two 2.5 Gb/s uplink unicast channels. Another advantage of this WDM-PON is that the broadcast channel only causes a small interference with the downlink/uplink unicast channels, and it is shared by all the ONUs. The effect of the optical carrier to subcarrier ratio on the bit error rate performance can be mitigated by increasing the extinction ratio of the delay interferometer used at the remote node.

High-Performance Semiconductor Optical Amplifier Modules at 1300 nm

Semiconductor-based optical amplifiers (SOAs) offer solutions to a variety of amplification requirements covering operational wavelengths ranging from 600 to 1600 nm. This letter reports on the design and performance of buried heterostructure SOA modules exhibiting state-of-the-art performance within the 1300-nm operational window. The first, a high-gain variant, is optimized for preamplification applications while the second is designed for use as a booster amplifier. Record low noise figure performances for packaged devices are reported

CogSeNet: A Concept of Cognitive Wireless Sensor Network

Cognitive Sensor Network (CogSeNet) is an intelligent based wireless sensor network system which relies on cognitive processes to provide a dynamic capability in configuring wireless sensor network. CogSeNet is a network structure formed by sensor nodes equipped with cognitive modules allowing them to observe their operating environment and allowing a decision can be derived. A series of actions result so that the nodes can adapt and achieve certain goals by an overall policy. These goals can be as simple as to provide robust connectivity or as complex as negotiate additional resources from neighbouring network groups to forward mission-critical data. In this paper, the concept of cognitive sensor network is reviewed and a preliminary case study is illustrated.

Adaptation of wireless sensor network for farming industries

In recent years, wireless sensor networks (WSN) have received considerable attention within agriculture and farming as a means to reduce operational costs and enhance animal health care. This paper examines the application of WSNs to livestock monitoring and the issues related to hardware realization. The core of this study is to overcome the aforementioned drawbacks by using alternative cheap, low power consumption sensor nodes capable of providing real-time communication at a reasonable hardware cost. In this paper, various factors i.e. radio frequency selection, channel bandwidth, etc. have been evaluated to provide a solution which can obtain real-time data from diary cattle whilst conforming to the limitations associated with WSNs implementations.

Lameness Affects Cow Feeding But Not Rumination Behavior as Characterized from Sensor Data

Using automatic sensor data, this is the first study to characterize individual cow feeding and rumination behavior simultaneously as affected by lameness. A group of mixed-parity, lactating Holstein cows were loose-housed with free access to 24 cubicles and 12 automatic feed stations. Cows were milked three times/day. Fresh feed was delivered once daily. During 24 days with effectively 22 days of data, 13,908 feed station visits and 7,697 rumination events obtained from neck-mounted accelerometers on 16 cows were analyzed. During the same period, cows were locomotion scored on four occasions and categorized as lame (n = 9) or not lame (n = 7) throughout the study. Rumination time, number of rumination events, feeding time, feeding frequency, feeding rate, feed intake, and milk yield were calculated per day, and coefficients of variation were used to estimate variation between and within cows. Based on daily sums, using each characteristic as response, the effects of lameness and stage of lactation were tested in a mixed model. With rumination time as response, each of the four feeding characteristics, milk yield, and lameness were tested in a second mixed model. On a visit basis, effects of feeding duration, lameness, and milk yield on feed intake were tested in a third mixed model. Overall, intra-individual variation was <15% and inter-individual variation was up to 50%. Lameness introduced more inter-individual variation in feeding characteristics (26–50%) compared to non-lame cows (17–29%). Lameness decreased daily feeding time and daily feeding frequency, but increased daily feeding rate. Interestingly, lameness did not affect daily rumination behaviors, fresh matter intake, or milk yield. On a visit basis, a high feeding rate was associated with a higher feed intake, a relationship that was exacerbated in the lame cows. In conclusion, cows can be characterized in particular by their feeding behavior, and lame cows differ from their non-lame pen-mates in terms of fewer feed station visits, faster eating, less time spent feeding, and more variable feeding behavior. Further, daily rumination time was slightly negatively associated with feeding rate, a relationship which calls for more research to quantify rumination efficiency relative to feeding rate.

Wireless Sensor Networks for Cattle Health Monitoring

This paper investigates an adaptation of Wireless Sensor Networks (WSNs) to cattle health monitoring. The proposed solution facilitates the requirement for continuously assessing the condition of individual animals, aggregating and reporting this data to the farm manager. There are several existing approaches to achieving animal monitoring, ranging from using a store and forward mechanism to employing GSM-based techniques; these approaches only provide sporadic information and introduce a considerable cost in staffing and physical hardware. The core of this solution overcomes the aforementioned drawbacks by using alternative cheap, low power consumption sensor nodes capable of providing real-time communication at a reasonable hardware cost. In this paper, both the hardware and software have been designed to provide real-time data from dairy cattle whilst conforming to the limitations associated with WSNs implementations.