VANET via Named Data Networking

the substrate noise generated by a synchronous and an equivalent asynchronous implementation of a simple function are compared and analyzed.Next, the analysis is expanded to examine the noise from a typical large digital block such as a synchronous CBL  processor and an asynchronous NCL  processor. In order to gauge the practical impact of the substrate noise on an analog block, the performance degradation of a delta-sigma modulator DSM is evaluated in the presence of the substrate noise from each processor. VANET via Named Data Networking These measurements provide insight into noise tolerant analog/RF circuit design techniques. CBL is currently the most popular type of logic architecture for digital circuits. For this type of architecture, a signal in the form of a clock is used to control data transfer between Boolean logic gates and flip-flops.

In many cases, the clock is a global signal that synchronizes all of the switching in the design, hence the name synchronous logic. However, as mentioned above, the clock signal is considered a major noise contributor from a substrate noise point of view.NCL designs circumvent this problem by completely eliminating the clock. VANET via Named Data Networking Instead, this delay-insensitive form of logicuses a handshaking protocol to propagate data. For example,once some block has completed an operation, an acknowledgement signal along with the data is sent to the next block. VANET via Named Data Networking The second block uses the data for its own operation and upon completion, sends an acknowledgment back. At this point, the first block voids the data and moves on to its next task. As expected, the lack of synchronization gives an NCL circuit a distinct advantage with respect to switching noise and supply noise.

VANET via Named Data Networkings

Both of these noise mechanisms are much lower for asynchronous circuits because uncorrelated switching means that the peak currents injected into the substrate are much lower at any given time. Power consumption is also slightly lower for NCLdesigns. VANET via Named Data Networking Intuitively, it may seem that the opposite is true since NCL gates need to complete a handshaking protocol for each equivalent CBL clock edge. However, it turns out that on average, the power consumption tends to be lower because NCL designs do not have to deal with any additional clock driving circuitry and because only relevant portions of the circuit are active at any given time to resolve mobility management in named data networking. One disadvantage with NCL circuits is that NCL designs are typically larger than their Boolean counterpart. The reason for this difference in size is because NCL gates have to maintain the additional overhead for holding state information The goal for this experiment is to measure the substrate noise from a synchronous block and an asynchronous block to determine which is noisier.

In order to achieve this goal, functionally identical CBL and NCL designs are placed on a chip and used as noise generators. The two designs have separate power rails in order to measure the substrate noise generated for each. For a fair comparison, the CBL block is clocked approximately at the equivalent operating speed of the NCL block. The equivalent operating speed is defined as the CBL clock frequency for which the total completion time of a given task or program is about the same for both designs. VANET via Named Data Networking With either the CBL or NCL circuit on, a sensing circuit is placed equidistance from the two blocks to measure the noise in the substrate. VANET via Named Data Networking A schematic of the sensing circuit is shown in This design is based on that from The simple differential pair has close to unity gain along with a very wide bandwidth for broadband noise measurements.

Automatic control on transmission power in wireless networking

Most of these methods attempt to reduce noise coupling by either blocking or actively canceling the noise in the substrate  An alternative approach is to reduce the amount of noise that is injected from the digital block For a typical clocked Boolean logic CBL design, the main sources of noise injection are the clock tree and synchronous switching. The clock tree, used to distribute the clock across the chip, represents a large capacitive load in terms of both power and noise generation. Synchronous switching noise is the result of thousands of digital gates switching relatively close in time.

Since the inductive portion of the noise coupling is heavily dependent on the time derivative of the supply current , these two noise sources are further magnified due to the current switching nature of conventional CMOS CBL designs. Automatic control on transmission power in wireless networking As a result, a number of new constant current logic families such as current-steering logic and current-balanced logic were proposed to reduce substrate noise. However, it was shown that the improvement offered, if any, from these two types of logic only occur when the inductive coupling portion was dominant  For small, lowinductance packages, the improvement over CMOS was negligible since the capacitive coupling portion is now dominant . Another technique to reduce the noise from the digital blocks is minimizing by spreading the transitions in time.

Automatic control on transmission power in wireless networkings

As mentioned above, synchronous switching causes a large number of digital gates to switch relatively close in time. Automatic control on transmission power in wireless networking Since all of this occurs in a relatively short time period, the effect of the injected noise tends to accumulate. When a global clock event occurs, the majority of the CBL transitions are concentrated around the same time, resulting in large noise. One possible approach is to intentionally skew the clock signal that is distributed to various domains on the chip. Although considerable improvement has been shown with this technique, there are practical limits on the extent of the skew and on the number of clock regions that are attainable. Even with an optimized solution, the switching is still fundamentally synchronized and the clock tree still presents itself as a major source of noise. Further improvement can be made if the transitions are somehow more evenly spread in time.

This can be made possible with a fully asynchronous design approach.  LE EXPERIMENTAL CHARACTERIZATION AND ANALYSIS OF AN ASYNCHRONOUS APPROACH With a clockless logic, data is assessed and propagated independently by each gate. Automatic control on transmission power in wireless networking Thus, switching is localized, and forthe most part, independent of activity elsewhere on the chip. Compared to the synchronous approaches, an asynchronous solution should inject less substrate noise because spreading out the transitions both reduces the inductive portion and disperses the accumulation effect of the capacitive component. A number of studies have demonstrated that asynchronous circuits have tremendous power and noise savings over their synchronous counterparts Prior work on the asynchronous implementation has shown that the supply current peaks and the corresponding emission spectrum of the asynchronous approaches is much lower than the synchronous counterpart.

The focus of this paper is on an evaluation of the noise injected into the silicon substrate and its propagation to sensitive analog circuitry for both asynchronous and synchronous circuits. As there are many different asynchronous design styles available, it would be difficult to provide a fair and comprehensive study of how the power and noise savings of asynchronous circuits translates to reduced noise injected into the substrate. As a result, this work has examined one representative type of asynchronous logic called NULL convention logic In this paper, Automatic control on transmission power in wireless networking

The different conclusions about transparency in engine torque and throttle versus vehicle speed also explicitly highlight the fact that transparency considerations inevitably depend on the signals of interest. Transparency is not an independent property of the system, and may be better for some output signals than others. In this particular work, for example, the transparency is better for the vehicle speed signal, because it is filtered through the vehicle inertia, and is thus smoother than the engine torque and throttle signals. Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software The different conclusions about the transparency for different output signals also point out different strategies for improving transparency. If the engine torque or throttle is the signal of interest, and a better transparency is desired, then the conclusion from the analysis is that the efforts to improve transparency should focus on reducing the effect of distributing the simulation  by changing the communication architecture rather than trying to compensate for delay, jitter, and/or loss of the Internet  by designing a Smith predictor, unless the delay is high. Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software If the signal of interest is vehicle speed, on the other hand, an improvement in transparency may require attention to time delay first as the delay increases. It is important to keep in mind that besides the output signal of interest, the transparency results presented above are also specific to the chosen coupling point and communication architecture. A different coupling point, such as at the engine output shaft, and a different communication architecture, such as one that is not event-based, but perhaps passive, could produce different results in terms of transparency. Hence, evaluating alternative coupling points and communication architectures Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software could be an interesting continuation of this work. The fact that the bandwidth of a human driver will not be as high as the driver model suggests that the transparency degradation may be even less significant from a human driver’s perspective. This also motivates the development of a frequency-based approach to analyzing transparency, and may also be an important future direction. The proposed transparency analysis technique provides away to characterize transparency in stochastic systems. Since it is a statistical analysis, all the conclusions regarding the significances of the observed differences, which lead to conclusions about the significances of the degradations in transparency, are to be understood in a statistical sense. Further engineering judgment would complement these statistical conclusions. Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software In other words, the proposed analysis only considers the statistical significance, but not the engineering significance. Hence, it is possible that even though the analysis Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software concludes that there is a statistically significant difference between two configurations, the difference may still be insignificant from an engineering point of view.THE trend toward integrated system-on-a-chip has resulted in combining analog and digital components on a single chip. Due to this integration, switching noise generated by the digital circuitry is coupled to the chip substrate through transistor junction, interconnect and bond-pad capacitances Supply noise from the digital supplies is also injected through the bulk connections of the digital gates. The combined effects of these two mechanisms results in large noise currents that can degrade analog performance by changing the transistor body potential and by altering the power and ground voltage levels In recent years, many techniques have been developed tosuppress the substrate noise coupling to analog circuitry. Designing a Peer Support System for Computer Programming Courses Using Online Social Networking Software

Autonomic Networking – from theory to practice

The first simulation of the first configuration is taken as the baseline, and the remaining simulations and all the other configurations are compared to this baseline response. The output signals of interest are chosen as engine torque, throttle, Autonomic Networking – from theory to practice and vehicle speed, to characterize the transparency from the different perspectives of the engine, driver, and vehicle, respectively. Before the statistical transparency analysis given in Section is applied, the raw data need to be aligned with respect to a common reference point. This point is taken as the instant the throttle command exceeds a threshold which is considered to mark the beginning of the simulation. Data collected before this point are ignored, which removes the data collected when the engine is idling before the simulation starts.

The analysis given in Section is then performed. Tables summarize the standard deviations in the selected output signals as defined by The one-way Autonomic Networking – from theory to practice ANOVA tables generated from these data are given in The extremely low p-values in all three ANOVA tables indicate that the null hypothesis that all configurations are the same for the signals considered is rejected with a significance level of. In other words, the variations of the signals show a statistically significant change in Autonomic Networking – from theory to practice at least one of the configurations. Thus, in at least one of the configurations there is a statistically significant loss in transparency Autonomic Networking – from theory to practice.

Autonomic Networking – from theory to practices

To obtain more specific results and to see how significantly each configuration affects the variation, pairwise comparisons for significant differences between the means of standard deviations of the signals are performed using Tukey’s method as proposed in Section. The results are visualized in, where the circles indicate the estimated mean standard deviations and the horizontal lines indicate the confidence intervals for the estimates. Overlapping confidence intervals are indicators of insignificant difference. The conclusion from is that the configuration pairs , are significantly different from each other, with a significance level for both engine torque and throttle data. This has a very important implication Autonomic Networking – from theory to practice that LAN- and Internet-distributed configurations are not significantly different from each other for these two signals. In otherwords, the change in transparency of engine torque and throttle is insignificant when the configuration moves from LAN distribution to Internet distribution with nominal delay.

Thus, the main source of degradation in transparency in this case is distributed simulation, and unless the Internet delay increases dramatically, it does not affect the transparency with respect to these two output signals significantly. When performed for the vehicle speed signal, Tukey’s test concludes that the significantly different pairs of configurations are , with a significance level of. Thus, another very important conclusion can be drawn from those results; namely, the change in variation, and thus, transparency, of vehicle speed is insignificant between Ideal, LAN-distributed, Autonomic Networking – from theory to practice and Internet-distributed configurations. Hence, as far as vehicle speed is concerned, the system can be considered transparen until the Internet delay increases dramatically. Autonomic Networking – from theory to practice.

Mapping of delay-sensitive virtual networks

Instead of at network interface level, such error checks are performed in the event-based framework by assigning unique event indices to all packets and using only the most recent ones. This ensures that both sites respond to the most up-to-date signals available. Mapping of delay-sensitive virtual networks Furthermore, a network characterization between Ann Arbor and Warren revealed that the packet drop rate is very low when using UDP. A typical result for round trip time delay versus timeof day for the network used in this paper is shown in its statistics are summarized in Table As Table I exemplifies, the drop rate was around for this network.

A packet is considered dropped in this case if it does not arrive within Such a low packet drop rate was preferred over increasing the delay by switching to TCP. also clearly shows a multimodal character in the sense that some packets experience a delay around and some around whereas others are dropped shown as zero delay in the figure. However, both the spikes and drops occur very infrequently as Table I shows, thereby further motivating the use of UDP. An increase in the network delay is simulated by bouncing the packets between Warren and Ann Arbor a number of timesbefore processing them. If the nominal round trip delay between Warren and Ann Arbor is approximately an effective network delay of for example, can be simulated by introducing additional round trips.

Mapping of delay-sensitive virtual network

Finally, it is worth emphasizing again that this communication architecture is chosen due to its ease of implementation and is not proposed or designed to give the lowest degradation in transparency possible or perform best in the sense of any other performance metric. This very communication architecture was also used in the human-in-the-loop experiments with the ID-HILS setup and it is desired in this work to stay as close as possible to the setup used in be able to generalize the conclusions to that setup, as well. Any transparency degradation due to this particular choice of communication architecture will be captured by the proposed transparency analysis. Mapping of delay-sensitive virtual networks Mapping of delay-sensitive virtual networks Four configurations are devised, each serving a different purpose. These are as follows. All models are integrated in a single simulation environment, simulated using a single numerical solver, in a computer that is directly connected to the engine. This configuration represents the baseline and is to help identify the variation inherent in the engine-in-theloop setup.

The models are distributed over the local area network LAN and co-simulated on two differen computers in Ann Arbor. This configuration is to help identify the variation introduced due to co-simulation using the adopted event-based framework. The delay introduced by theLANwas considered negligible. The models are distributed over the Internet, and the driver and vehicle models are simulated in Warren, while the driveline model is simulated in Ann Arbor and interacts with the engine. This configuration is to help identify the variation introduced due to distribution over the Internet using the event-based framework and with the nominal roundtrip time delay of approximately between Ann Arbor and Warren.The models are distributed over the Internet as in the  configuration, however additional round trips are introduced into the communication protocol to increase the delay up to, a number representative of coast-to-coast delay in the U.S. This configuration is to help identify the variation introduced due to the additional delay. Mapping of delay-sensitive virtual networks Each configuration is simulated five times except for the first one, which is simulated six times.

Opportunistic networking for improving the energy efficiency of multi-hop cellular networks

where mvehicle is vehicle mass, Jwheel is wheel inertia, Opportunistic networking for improving the energy efficiency of multi-hop cellular networks b is viscous damping coefficient, rwheel is wheel radiusis wheel speed, and are vehicle and wheel accelerations, respectively. Furthermore, fslip , faero, frolling are wheel slip, aerodynamic resistance, and rolling resistance forces, respectively, and τdifferential and τbrake are differential and brake torques, respectively, and they are given by is the normal tire force, is the friction coefficient, ,max is the wheel slip for force saturation, where A is the vehicle frontal area, ρair is the air density, Cd is the aerodynamic drag coefficient, and x˙ is vehicle velocity, where ai are empirical coefficients, and P is the tire pressure, and where is viscous damping coefficient, FCoulomb is the static Coulomb force, and cbrake is the brake command from the driver.

The parameter values are given in Table in the Appendix. Finally, this section describes the architecture used for communicating the coupling variables over the Internet between Warren and Ann Arbor. Opportunistic networking for improving the energy efficiency of multi-hop cellular networks Different communication architecturesexist in the literature, including both wave variable-based and event-based architectures. This work adopts an eventbased communication architecture similar to Xi and Tarn and Elhajj primarily because of its ease of practical implementation. The event-based framework may also have additional attractive stability-, transparency-, and synchronizationrelated properties under some assumptions of isomorphism between its “event domain” and the time domain.

Opportunistic networking for improving the energy efficiency of multi-hop cellular network

This paper does not explore the validity of these underlying assumptions in the context of ID-HIL simulation. Instead, it focuses on evaluating the transparency properties of the framework directly using experimental data. Ongoing work by the authors is also examining different approaches to improving these transparency properties, Warren site acts as the client and the Ann Arbor site acts as the server. Opportunistic networking for improving the energy efficiency of multi-hop cellular networks Warren site sends updated transmission speed and throttle signals at a frequency Communication flowchart for the Warren site. Communication flowchart for the Ann Arbor site. regardless of whether it receives a response or not. Ann Arbor site, on the other hand, only responds to the packets it receives, it only sends an updated transmission torque signal when it receives a packet from Warren. illustrate the communication flowcharts for Warren and Ann Arbor sites, respectively. The signals received at both sites are incorporated into the local models through filters to allow a smoother transition and protect the hardware.

Specifically, the Warren site uses a filter that linearly increases the transmission torque value from its previous value to its new value in The Ann Arbor site, on the other hand, uses a first order filter of the form with a time constant of and thus, a settling time of approximately. Therefore, on both sites, the signals reach their new values by the next communication event, which happens every according to the simulation clock of the Warren site. This paper does not consider synchronization of the clocks in the ID-HIL setup. It is acknowledged that working with asynchronous clocks may introduce further degradation in transparency, but it is also noted that such adverse effects of lack of synchronization will also be captured by the proposed transparency analysis. The communication is handled using the User Datagram Protocol UDP is preferred over the Transmission Control Protocol TCP in this work because of its minimalistic, expense of a guarantee of delivery, Opportunistic networking for improving the energy efficiency of multi-hop cellular networks ordering, or duplicate protection. This means that the packets may arrive out of order, in duplicates, or not at all, but as a benefit of this lack of network interface level error checks, the communication delay is reduced, which is more critical for the purposes of ID-HILS.