Pulse interspersing in static multipath chip environments for Impulse Radio communications

Communications are becoming the bottleneck in the performance of Chip Multiprocessor (CMP). To address this issue, the use of wireless communications within a chip has been proposed, since they offer a low latency among nodes and high reconfigurability. The chip scenario has the particularity that is static, and the multipath can be known a priori. Within this context, we propose in this paper a simple yet very efficient modulation technique, based on Impulse Radio-On–Off-Keying (IR-OOK), which significantly optimizes the performance in Wireless Network-on-Chip (WNoC) as well as off-chip scenarios. This technique is based on interspersing information pulses among the reflected pulses in order to reduce the time between pulses, thus increasing the data rate. We prove that the final data rate can be considerably increased without increasing the hardware complexity of the transceiver.Peer ReviewedPostprint (published version

Scalability of broadcast performance in wireless network-on-chip

Networks-on-Chip (NoCs) are currently the paradigm of choice to interconnect the cores of a chip multiprocessor. However, conventional NoCs may not suffice to fulfill the on-chip communication requirements of processors with hundreds or thousands of cores. The main reason is that the performance of such networks drops as the number of cores grows, especially in the presence of multicast and broadcast traffic. This not only limits the scalability of current multiprocessor architectures, but also sets a performance wall that prevents the development of architectures that generate moderate-to-high levels of multicast. In this paper, a Wireless Network-on-Chip (WNoC) where all cores share a single broadband channel is presented. Such design is conceived to provide low latency and ordered delivery for multicast/broadcast traffic, in an attempt to complement a wireline NoC that will transport the rest of communication flows. To assess the feasibility of this approach, the network performance of WNoC is analyzed as a function of the system size and the channel capacity, and then compared to that of wireline NoCs with embedded multicast support. Based on this evaluation, preliminary results on the potential performance of the proposed hybrid scheme are provided, together with guidelines for the design of MAC protocols for WNoC.Peer ReviewedPostprint (published version

Scalability of the channel capacity in graphene-enabled wireless communications to the nanoscale

Graphene is a promising material which has been proposed to build graphene plasmonic miniaturized antennas, or graphennas, which show excellent conditions for the propagation of Surface Plasmon Polariton (SPP) waves in the terahertz band. Due to their small size of just a few micrometers, graphennas allow the implementation of wireless communications among nanosystems, leading to a novel paradigm known as Graphene-enabled Wireless Communications (GWC). In this paper, an analytical framework is developed to evaluate how the channel capacity of a GWC system scales as its dimensions shrink. In particular, we study how the unique propagation of SPP waves in graphennas will impact the channel capacity. Next, we further compare these results with respect to the case when metallic antennas are used, in which these plasmonic effects do not appear. In addition, asymptotic expressions for the channel capacity are derived in the limit when the system dimensions tend to zero. In this scenario, necessary conditions to ensure the feasibility of GWC networks are found. Finally, using these conditions, new guidelines are derived to explore the scalability of various parameters, such as transmission range and transmitted power. These results may be helpful for designers of future GWC systems and networks.Peer ReviewedPostprint (author’s final draft

On the area and energy scalability of wireless network-on-chip: a model-based benchmarked design space exploration

Networks-on-Chip (NoCs) are emerging as the way to interconnect the processing cores and the memory within a chip multiprocessor. As recent years have seen a significant increase in the number of cores per chip, it is crucial to guarantee the scalability of NoCs in order to avoid communication to become the next performance bottleneck in multicore processors. Among other alternatives, the concept of Wireless Network-on- Chip (WNoC) has been proposed, wherein on-chip antennas would provide native broadcast capabilities leading to enhanced network performance. Since energy consumption and chip area are the two primary constraints, this work is aimed to explore the area and energy implications of scaling a WNoC in terms of (a) the number of cores within the chip, and (b) the capacity of each link in the network. To this end, an integral design space exploration is performed, covering implementation aspects (area and energy), communication aspects (link capacity) and networklevel considerations (number of cores and network architecture). The study is entirely based upon analytical models, which will allow to benchmark the WNoC scalability against a baseline NoC. Eventually, this investigation will provide qualitative and quantitative guidelines for the design of future transceivers for wireless on-chip communication.Peer ReviewedPostprint (author’s final draft

The influence of internal partitions on the air movement and contaminant dispersion in mechanically ventilated rooms

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN060656 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Indoor Air Quality and ventilation assessment of rural mountainous households of Nepal

Cooking with open fire has been crucial for occupants’ health due to poor Indoor Air Quality (IAQ) in most of the rural households. IAQ is affected by many factors, such as firewood moisture, stove type, ventilation, etc. A monitoring system has been developed to find the general IAQ with Improved Cooking Stove (ICS) and Traditional Cooking Stove (TCS). Decay curve technique is utilized to calculate the Carbon Monoxide (CO) decay time. A preliminary health survey is also carried out to evaluate the dweller’s health complaints. The study is carried out in two adjoining remote villages of Palpa District in Western Nepal. The mean CO and PM2.5 concentration for ICS and TCS are 27.11 ppm and 825.4 μg/m3 (27.11 ± 14.24 ppm and 825.4 ± 730.9 μg/m3) with significant correlation (p < 0.0001) and 36.03 ppm and 1336 μg/m3 (36.03 ± 19.06 and 1336 ± 952.8) with significant correlation (p < 0.0481), respectively. From the overall sample, the mean CO and PM2.5 concentration is reduced by 29.9% and 39%, respectively. The ventilation analysis result shows more than an 80 percentage deficit in ventilation as per the minimal rate of ventilation as prescribed by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Moreover, the placement of chimney at a short vertical height of 1.2 m adjoining to back window is the major cause of backflow. Therefore, the study has recommended a greater focus on ventilation to control IAQ of rural mountainous households