1. Faster Design Time
Traditionally, PCB designers treat signals as a set of pins connected to one another (commonly called nets). This approach can cause problems in high-speed designs because it fails to account for signal paths through series components and branches. These extra pathways can result in pessimism that needs to be corrected during simulation. This is a time-consuming process that can be error prone. The new xSignal functionality, introduced in Altium Designer 15.0, allows the designer to define clusters of signal paths – known as xSignals – that can be targeted by design rules such as Matched Length.
Using the xSignals Wizard, the designer can quickly define a set of end-to-end xSignals by selecting source and destination components, the nets connecting them and the destination component pads that require matched length tuning. The Wizard then analyzes all potential signal paths – including those through series passive components and branches – to identify potential xSignals. The first page of the Wizard identifies the overall end-to-end xSignals, and the subsequent pages will define xSignal classes and Matched Length design rules for the xSignals selected.
2. Reduced Costs
Using xsignal to define the signal path allows multiple nets to be treated as one for the purposes of length matching. For example, a net that starts on an IC pin, terminates on a resistor and continues to another IC can be defined as an xsignal. The total path of the xsignal is the first net plus the length of the path through the resistor and then the second net. This simplifies the length matching process and reduces routing costs.
To create an xsignal, select the required series termination components and use the Design >> xSignals sub-menu or right-click on the xSignals panel region. The Create xSignals from Connected Nets command opens the xsignal business Class dialog where you can select an existing xsignal class or type in a name to create a new class.
Once a class is selected it will appear in the xSignal mode of the PCB panel. The right-click context menu offers the ability to edit (Add Class, Change XSignal Color, etc) and remove (Delete) the class.
3. Reduced Risk
The use of xSignals significantly reduces the risk of creating paths which are either incomplete or have undesirable lengths, and helps ensure that any length matching required is performed at an appropriate level of detail. This is especially important when using fly-by or T-branch designs for memory circuits, where the designer has control over the number of xSignals created at each signal branch point and how long they are.
To create xSignals, use the Create XSignal Between Components Wizard. Select the source component and nets of interest, then select the target components to designate. The software will then analyze the selected source and destination components, identifying all potential paths between the two. These are listed in the lower region of the xSignals dialog and all will be enabled for creation.
4. More Efficient Routing
A similar concept to NAT ports on your router, xsignals are signal paths that allow you to scope specific design rules during routing tasks. A xsignal can be created between any two signals on your board, whether they are located on the same net or in associated nets.
In proactive link state routing such as OLSR, dynamic link metrics introduces a flapping path behavior where communication paths are constantly changing [12]. This feature makes networks more robust and resilient, however, it also increases the risk of several inconvenient phenomena such as packet looping.
In this paper, we propose a method to reduce the number of loop packets in OLSR by incorporating signal preemption into the path selection process. We show that the proposed strategy is capable of significantly improving EV travel time in signalized corridors. Moreover, we analyze the impact of the proposed method on traffic flow and vehicle performance under various network conditions. In particular, we study the impact of cycle length and green time duration of traffic signals on the travel time of EV.
